Channel switching amp including pwr attenuator levels
Cybermonk
with large cab, or the 15 watt Aiken Invader amp with built-in
power attenuator?
http://www.amptone.com/cornfordharlequin.htm
http://www.amptone.com/aikeninvader.htm
One of the hardest problems in programmable tone with a tube
power amp is that for some sounds, you want the power amp to be
heavily saturated, but for other sounds, you want lots of
headroom. Imagine adding on a Hot Plate or Power Brake to a
dual master-volume, channel-switching amp such as:
Clean channel: gain, eq, volume
High-gain channel: gain, eq, volume
Imagine the power attenuator fixed at 9 dB attenuation.
When you stomp the channel-switching footswitch, this changes
the preamp distortion depth and the depth of power-tube
saturation -- but it cannot change the amount of power
attenuation.
I have lately wondered why THD put their UniValve amp with built-
in power attenuator on hold, and switched all their efforts into
the Hot Plate add-on outboard power attenuator. Now Aiken makes
an amp that has an integrated standard power attenuator. If you
buy an outboard attenuator, you can use it with any amp. But if
you integrate a power attenuator into an amp, it offers more
control, potentially.
Aiken's page has a fatal omission -- he doesn't list the
controls. He doesn't even say whether the amp has channel
switching. So I am left to speculate.
Suppose the Aiken amp currently has two conventional channels as
spec'd above. The channel footswitch controls the depth of
preamp distortion, and the depth of power tube saturation, but
does not control the third key volume control, which is the post-
output transformer attenuation amount.
How does the Guytron amp compare? It probably does not enable
you to simultaneously switch the depth of preamp distortion and
the depth of (mid-chain) power-tube saturation and the final
power to the speakers.
So this is a great idea that no one has implemented yet. A
comparable idea is a MIDI-controlled power attenuator, or
Bradshaw-type switcher control of attenuation amount (picture
the appropriate Palmer rack attenuator model, with MIDI control).
Also consider using channel-switching to switch to a single
speaker (such as one 12" speaker in a 2x12 cab) when the goal is
cranked-power-tube sound at private or coffeehouse SPL.
The idea is to modify the Aiken Invader so that stomping the
channel footswitch simulataneously changes the three key level
controls:
o preamp distortion
o power-tube saturation
o power attenuation
This would be equivalent to having two single-channel master-
volume amps, each with their own power attenuator, driving a
single cab. Each amp has its own preamp gain setting, master
volume setting, and power attenuation setting. Master volume is
a serious misnomer. The real master volume is the attenuator
control.
-----------------------------------------------------------
Got questions? Get answers over the phone at Keen.com.
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Randall Aiken
is still under construction, and in fact, the entire website is
going through an overhaul. There will soon be additional
pictures, and the front and rear panel controls/connections have
been recently added.
I thought the spec sheet made it clear that the amplifier was
based on the old plexi/1987/bassman 4-input designs. If you are
at all familiar with these classic amplifiers (as everyone should
be!), you will know that they are not channel-switching designs.
Rather, they allow mixing of the two inputs by "jumpering" the
two channels and adjusting the individual volumes, which are
voiced differently, to achieve a wide range of tonal coloring.
In fact, the two volume controls actually function as a second
set of tone controls at the front end of the amp. The overall
level sets the amount of overdrive, and the balance between the
two determines the tone.
Modifying the amplifier for channel-switching preamp distortion
as you suggest would kill the entire soul of the amplifier! That
is not at all the intention of the product. It is designed for
players who like to control the gain of the amplifier just by
using the guitar's volume control. True "touch-sensitive"
distortion is not acheived solely through output stage distortion
alone, nor through preamp stage distortion. It is the balance
between the two that determines the tonal characteristics and
"feel" of the amp. Proper gain scheduling, i.e., determining at
what point each stage transitions to clipping, is an important
part of the equation.
The attenuator is included to keep the overall volume at a
reasonable level in either studio or stage use. The
transformer-coupled, balanced XLR output allows the actual signal
off the output transformer to be sent to the FOH mixer or the
studio board, suitably filtered to match the frequency response
of a 4x12 miked with an SM-57 off-axis. Basically, this
amplifier is designed for those who love the sound of the old
non-master Marshalls, but don't want to deal with the
ear-splitting volume required to get the overdriven tone. The
addition of a three-knob reverb, with dwell, tone, and level
controls, completes the package.
Keep checking back at the website for updates, as we are adding
things quite often.
Randall Aiken
http://www.aikenamps.com
Lord Valve
is an A/B box. If you want to be really snazzy about it, you
can use a pan pedal, and wipe your signal from input to input,
or anywhere in between. Marshall tone with good reverb?
What'll they think of next...
LV
ecar
about a purchase.
Cybermonk
forward to a list of the ten pots shown in the Invader picture.
>If you are at all familiar with these classic amplifiers (as
everyone should be!)
You should not expect potential customers to be familiar with
the Bassman or Plexi amps. While the Bassman may be the center
of your world, it's a big world. It's a little alienating to
some customers if you only care to address people who already
know what controls are on those amps. It is interesting how the
Korean article about guitar amp history has quite a different
view of the importance of preamp distortion and warns Korean
guitarists that they might not like the sound of non-master
volume amps.
http://www.harmony-central.com/Guitar/guitar-amp-evolution.html
Non-master volume amp design, with locked-together control of
preamp distortion and power-tube saturation, can be called "the
soul of the amp". But a master volume design could enable
greater flexibility and greater control. As long as it is
possible to have a short signal path (not passing through too
many gain stages) and push the power tubes into strong
saturation without any preamp distortion required, I see nothing
wrong or limiting with master volume architecture. A master
volume setup could potentially provide all the sounds of a non-
master volume design, and also provide more sounds. You could
call that flexibility "killing the soul of the amp", or you
could call it "expanding the soul of the amp".
Master volume designs *tended* to force you to use more preamp
distortion and less power-tube saturation, but a master volume
does not *inherently* mean preventing you from getting a classic
combination, which is a little preamp distortion with a lot of
power-tube saturation.
The ideal amp would enable all combinations of:
o Any depth of preamp distortion
o Any depth of power-tube saturation
o Any final volume
Would such an amp have no soul? It would be more like having
every soul.
Instead of hauling around and spending money on two amps, I am
interested in how to use a multi-contact A/B switch to use a 2-
channel preamp, single power amp, single power attenuator, and
single speaker to act as a channel switching amp that provides
two presettable levels of preamp distortion, power-tube
saturation, and power attenuation. I would like to apply
programmable amp concepts to classic, simple amp designs -- but
I would like to have master volume, independent control of the
amount of preamp distortion and power-tube saturation.
Or, if you really want to lock together the depth of preamp
distortion and the depth of power-tube saturation, I would like
to have simultaneous channel-switching control of the amp
distortion and the power attenuator setting. This would enable
switching between quiet, intense power tube saturation, and loud
clean sound -- all with a single amp. The footswitch controls
the power attenuation as well as locked-together preamp and
power amp distortion intensity, so the footswitch could toggle
between quiet soaked and loud clean, as follows:
A.
Medium preamp distortion
High power-tube saturation
Medium SPL
B.
Low preamp distortion
Medium power-tube saturation
High SPL
Punkerdubh
Lord Valve <detr...@ix.netcom.com> wrote (in part):
> Marshall tone with good reverb? What'll they think of next...
. . . Marshall and good reverb??
. . . . . In the same sentence???
Extreme cognitive dissonance, dude!!
- Punkerdubh
Stefan Markowitz
Cybermonk schrieb in Nachricht
<007352e8...@usw-ex0102-013.remarq.com>...
---snip---
>So this is a great idea that no one has implemented yet. A
>comparable idea is a MIDI-controlled power attenuator,
This would be easy to implement. But it does not make sense
to me because the attenuator would deteriorate my tone.
However, there is no technical problem. I´ve modified
my amp for MIDI-controlled switching between 2 and 4
output tubes.
Stefan
Cybermonk
amp* configurations and settings, not just preamp settings.
Do you really think that power attenuators impede Tone? Of
course if you drive four 70-watt speakers with 60 mW total, so
that each 70-watt speaker receives only 15 mW, that's running
each speaker at only a small fraction of its rated power, and
the speakers sound fizzy and thin. But as long as you push each
speaker to at least 1 watt (which is pretty loud, especially
with 4 speakers each running at this level), you get decent
speaker smoothing.
I think that the bad reputation of power attenuators is due to
people using too many speakers, rated at too high power, with
extreme attenuation. What do you think about this? If we're
making a simple mistake in the way we use power attenuators, and
they actually can sound great when sending 1 watt through to a
single speaker, that changes everything and opens up great,
practical Tone that can compete with volume-independent amps
such as modelling amps.
Tube amp makers need to find a way to provide attenuation and
variable-SPL control, as well as easy tonal flexibility, or they
stand to lose a lot of business to modelling amps, which are
remarkably practical for home and stage, and flexible in voicing.
There are also power-supply and biasing approaches that provide
wattage control without using post-output transformer
attenuation. I would like to see a MIDI-controlled version of
the Maven Peal tube power amp or London Power: Studio or Session
power-scaling amp.
I don't think it is correct to make a rigid association between
non-master-volume amps and the ability to control the amount of
distortion by using the guitar's volume control. There's no
difficulty in designing an amp that has a pot for preamp gain
(Gain) and a pot for power-tube saturation (Master Volume) that
would permit you to set the Gain at 4 and the Master Volume at
10, and get the exact same sound and distortion control at your
guitar as when you play through a non-master volume amp with its
single volume control set to 10. Everyone says that non-master
volume amps permit this control at your guitar, as though master
volume amps prevent you from doing the same thing.
As long as the master volume amp is flexible in its levels and
number of gain stages, it provides a superset of the settings
that are possible on a non master volume amp. If guitarists
habitually use too much preamp distortion gain and too little
power amp saturation with a master volume amp, don't blame the
amp, blame the user. And blame the industry for rejecting power
attenuation after mistakenly running too many speakers, with too
high power rating, at too extreme attenuation.
There is nothing limiting about having a master volume. And
there is nothing limiting about using a power attenuator, as
long as you disconnect all but 1 speaker and push it to 1 watt,
as the lowest limit of your SPL. The ideal amp would have
master volume and a power attenuator, with channel switching
that controls the attenuator, as well as the master volume and
early gain.
If some existing amps with these type of features cannot produce
the classic Tone of minimalist amps (as well as a wide range of
other good sounds) it is just due to poor implementation, not
due to the use of master volume, channel switching, MIDI
control, or a power attenuator.
Randall Aiken
> Thanks for the clarification of the Invader specs; I look
> forward to a list of the ten pots shown in the Invader picture.
>
They are listed on the specification sheet shown on my website.
> >If you are at all familiar with these classic amplifiers (as
> everyone should be!)
>
> You should not expect potential customers to be familiar with
> the Bassman or Plexi amps. While the Bassman may be the center
> of your world, it's a big world. It's a little alienating to
> some customers if you only care to address people who already
> know what controls are on those amps.
I don't expect people to be familiar with them, although, I would think
that it would be hard to find a serious guitarist who didn't know about
non-master Marshall amplifiers! If you haven't heard one of these
classic amps cranked up, you owe it to yourself to listen to one! You
are missing out on one of the real treats of life.
It is not that I "care only to address people who already know what
controls are on those amps". With all due respect, Cybermonk, you have
taken an under-construction spec sheet off my website (which I just put
up a couple of days ago and am still working on, as it mentions on the
home page), copied it, put it up on your site and on this newsgroup,
and proceeded to publicly criticize it without even asking me for
clarification. There will be more specifications, more pictures, and
more detailed pricing information, broken down by speaker choice. I am
sorry it isn't complete yet, but I wanted to get something up because so
many people were asking me about it and wanting to see a picture of the
amp. It is a work in progress, as is mentioned on the site.
> Non-master volume amp design, with locked-together control of
> preamp distortion and power-tube saturation, can be called "the
> soul of the amp". But a master volume design could enable
> greater flexibility and greater control. As long as it is
> possible to have a short signal path (not passing through too
> many gain stages) and push the power tubes into strong
> saturation without any preamp distortion required, I see nothing
> wrong or limiting with master volume architecture. A master
> volume setup could potentially provide all the sounds of a non-
> master volume design, and also provide more sounds. You could
> call that flexibility "killing the soul of the amp", or you
> could call it "expanding the soul of the amp".
>
> Master volume designs *tended* to force you to use more preamp
> distortion and less power-tube saturation, but a master volume
> does not *inherently* mean preventing you from getting a classic
> combination, which is a little preamp distortion with a lot of
> power-tube saturation.
>
> The ideal amp would enable all combinations of:
> o Any depth of preamp distortion
> o Any depth of power-tube saturation
> o Any final volume
>
> Would such an amp have no soul? It would be more like having
> every soul.
>
Again, you are completely missing the point of my amplifier. It is
designed for those people who appreciate the classic amplifiers of the
past, such as the non-master Marshalls it is patterned after, but
without the extreme volume. People who like those amps don't usually
care for master volumes, high-gain preamps, and channel switching. I am
sorry if it doesn't meet your definition of the "ideal" amplifier, but
it wasn't intended to. Putting a master volume, channel-switching, and
a high-gain preamp would indeed kill the soul of this amplifier. If I
wanted to design a high-gain channel-switcher, I would have. In fact, I
have one I am designing on the bench right now, but that's a different
model entirely. This amp is what it is, and I'm damned proud of it! It
exactly fits the niche I intended it to.
Thanks for your concern,
Randall Aiken
http://www.aikenamps.com
Ericb
<rea...@aikenamps.com> wrote:
Dignified responses Randall...Cybermonk seems quite the unit, and I've
been waiting for years for his own line of amps, instead of his critique
of everyone else's!
ERIC
Cybermonk
picture.
>They are listed on the specification sheet shown on my website.
They are there now.
It's interesting that there is an intersection between
guitarists who want a purist, classic amp, and guitarists who
are willing to consider using a power attenuator. Some people
who want a single-channel, non-master volume tube amp are likely
to dismiss a power attenuator as well. I hope you provide a
variety of amps with built-in power attenuator. I think of a
power attenuator the same way as a master volume: at one extreme
setting, it is bypassed -- so that having a master volume
available in the amp, or having a power attenuator available in
the amp, provides a superset of functionality.
The tube amp resurgence of the past decade has raised the bar
for good Tone, and the modelling amp trend has established a
breakthrough in functionality, versatility, and ease of use
(practicality). I'm sure this practicality and good Tone can
somehow be effectively combined into a single amp. I picture
the merging of a modelling amp that has the great Tone of tube
amps, and tube amps having the practicality and versatility of a
modelling amp.
Stefan Markowitz
Cybermonk schrieb in Nachricht
<2488cbab...@usw-ex0103-018.remarq.com>...
>Do you really think that power attenuators impede Tone?
Yes. The dynamics and frequency response is altered.
The punch is getting lost. It is something like switching from
pentode to triode mode. I don´t like that sound.
>I think that the bad reputation of power attenuators is due to
>people using too many speakers, rated at too high power, with
>extreme attenuation. What do you think about this?
Maybe it is a matter of taste, but for me attenuators don´t work.
I´m not talking about extreme attenuation.
>Tube amp makers need to find a way to provide attenuation and
>variable-SPL control, as well as easy tonal flexibility, or they
>stand to lose a lot of business to modelling amps, which are
>remarkably practical for home and stage, and flexible in voicing.
That´s why I´m playing a Yamaha DG amp now.
>I don't think it is correct to make a rigid association between
>non-master-volume amps and the ability to control the amount of
>distortion by using the guitar's volume control. There's no
>difficulty in designing an amp that has a pot for preamp gain
>(Gain) and a pot for power-tube saturation (Master Volume) that
>would permit you to set the Gain at 4 and the Master Volume at
>10, and get the exact same sound and distortion control at your
>guitar as when you play through a non-master volume amp with its
>single volume control set to 10. Everyone says that non-master
>volume amps permit this control at your guitar, as though master
>volume amps prevent you from doing the same thing.
There´s nothing wrong with a master volume if it is cranked. :-)
The problem is: if you have discovered how good your amp is
sounding when cranked to output stage saturation, then you
will realize that the master volume is useless.
For the guitar´s volume control: Some amps are great responding,
others are not. Of course, if you have an amp with master volume,
there´ll be a big difference in response depending on the setting of
the master volume. But if it is cranked, there´ll be no difference to
another amp without master volume (assuming that both amps
are identical except to the master volume pot).
Stefan
Randall Aiken
>
> It's interesting that there is an intersection between
> guitarists who want a purist, classic amp, and guitarists who
> are willing to consider using a power attenuator. Some people
> who want a single-channel, non-master volume tube amp are likely
> to dismiss a power attenuator as well. I hope you provide a
> variety of amps with built-in power attenuator. I think of a
> power attenuator the same way as a master volume: at one extreme
> setting, it is bypassed -- so that having a master volume
> available in the amp, or having a power attenuator available in
> the amp, provides a superset of functionality.
>
I don't think people who want a single-channel non-master amp are that
likely to dismiss a power attenuator (unless it kills the tone, which
most of them do). In fact, everyone I know (myself included) who owns
old non-master Marshalls uses an attenuator either live or in the
studio. Just check out the popularity of the THD Hotplate - those
things are selling like hotcakes. You just can't crank up 100W (or even
50W) of Marshall power without threats of eviction from the club
owners. Even a little 15W amp is quite loud when fully cranked. I did a
side by side comparison of my 15W amp with a Sovtek Mig50 that was
running two EL34 with 550V on the plates - mine was almost as loud. The
addition of the built-in attenuator makes the amp much more usable in a
variety of situations.
The power attenuator is in a way like a master volume, except for one
important detail - the master volume only allows preamp stage distortion
(sometimes including the phase inverter, sometimes not). This usually
gives a less than ideal tone, because the output stage is not being
overdriven, which is where a lot of the characteristic tone of the amp
comes from. In addition, the extra preamp gain usually makes it more
difficult to get a good clean tone by rolling back the guitar volume,
and the tonal shaping to get a good, non-buzzy distortion tone makes
the clean sound less desirable, unless you build in channel-switching to
change to a different circuit path for clean. This is not to say that
you can't design a great sounding master volume amp - Soldano has proven
this with his excellent SLO-100 amp. However, it is a different type of
tone/feel. I think there is room for both types of amps, and my
upcoming product line will reflect this.
Randall Aiken
http://www.aikenamps.com
Cybermonk
70s. Instead of adding the master volume feature to enable a
kind of distortion at lower levels, they should have added power
attenuation (whether through soaking away excess energy or
restricting the power supply). Many people still want preamp
distortion available as a controllable option.
Very few amps have power attenuation built in.
THD announced the Uni-Valve amp at the same NAMM as the Hot
Plate, and ended up putting the Uni-Valve on hold until now.
The Koch Twintone amp and some others have power attenuation but
only a couple steps.
London Power provides power-supply-based power attenuation.
Maven Peal implies that their attenuation is power-supply based
as well.
The Guytron doesn't have a power attenuator; the mid-stage tube
power amp is run into a full dummy load, then a conventional
tube power amp brings the level back up to push the speakers.
Same with the Rail Rocket design at ax84.com.
The JayTronics Tru-Tone 2-watt tube amp has built-in power
attenuation "enabling full power-valve saturation down to a
fraction of a watt, without degradation of tonal qualities".
The Jim Kelley FACS 112 amp was packaged with an outboard power
attenuator.
What are the pros and cons of outboard versus built-in packaging
of a power attenuator? That's a question like preamp distortion
integration. An integrated power attenuator could enable better
integration and ease of use, including ease of transport. There
are various ways to integrate the power attenuator. The Invader
provides a convenient, elegant control on the front of the amp,
and a heavier power transformer that assumes pushing the tubes
to full power continuously.
It's ironic that tube amp purists often end up adding a
distortion pedal before the amp and a power attenuator
afterwards -- this is like going with a modular, rack oriented
approach as opposed to an all-in-one approach -- especially if
you use a separate head and cab. You could string the products
out across the floor:
dis/od pedal
purist, simple, elegant vintage head
power attenuator
cab
That's four pieces of gear. Would we rather have just one? An
amp with od/dist onboard, and of course a tube power amp, and a
built-in power attenuator, in a combo cab.
I think the Power Brake with inductive load has slightly more
dynamic depth and roundness than the resistive Hot Plate load.
But the Power Brake is twice the height and weight of the much
better looking Hot Plate. The Hot Plate is more transportable.
The Power Brake is like a very large brick. With outboard
attenuators you have to buy additional cables and take the time
to hook them up.
Info/links for these are at http://www.amptone.com; search the
home page.
If someone buys the Invader to obtain private cranked-amp tone,
shouldn't they order the 1x12 version rather than the 2x10 or
2x12 version? The lower the total wattage rating of the speaker
system, the more speaker smoothing you will obtain at the 1 watt
level. For a tube amp with a lot of flexibility of venue, it
could have two low-wattage speakers, and a switch to disconnect
one for the living room or coffeehouse or bookstore gigs.
Bookstore gigs are not unusual. The chain bookstores with audio
sections like to have live music including rock guitar. Tube
amp makers *can* address this venue and do not have to concede
this market to the modelling amps.
Cybermonk
are that likely to dismiss a power attenuator (unless it kills
the tone, which most of them do).
I'm skeptical about the common assertion that a power attenuator
kills the Tone. Which ones kill the tone? You have A/B'd the
Power Brake and Hot Plate, haven't you? Is the Invader's built-
in attenuator somehow better than the unnamed average power
attenuators you have in mind? I guess it is a resistive
attenuator with EQ compensation that affects the more extreme
attenuation settings, like the Hot Plate.
After running the Hot Plate right and getting great sound
despite the horrible sound it initially produced with a 4x12
cab, and then A/B'ing the sometimes maligned Power Brake against
the Hot Plate with impressive results from the Power Brake, I
suspect the *only* thing significantly bad sounding about
attenuators is when you run too many speakers, at far too low a
level for each speaker to start smoothing out.
I don't have a tremendous range of experience with various amps
and attenuators, but I have enough to conclude that when an
attenuator is used well, it has more potential than is often
claimed, as a general class of device.
Guitarists right now have diverging views of power attenuators.
Collectively, guitarists aren't sure whether to dismiss them as
tone sucking devices or not. The bad results I've had have
occurred when pushing the speakers at less than 1 watt per
speaker -- I have not heard a compelling difference between
power resistors, Power Brake (R/L), or Hot Plate. But the most
notable thing about the Hot Plate is its EQ compensation
switches which apply to the most extreme attenuation levels.
And the Hot Plate has more features than some others -- it's a
nice design. Other than that, I'm skeptical that there's much
difference between the sound of various attenuators.
Randall Aiken
> If someone buys the Invader to obtain private cranked-amp tone,
> shouldn't they order the 1x12 version rather than the 2x10 or
> 2x12 version? The lower the total wattage rating of the speaker
> system, the more speaker smoothing you will obtain at the 1 watt
> level.
Where did you get this idea? The difference is not in the smoothness of
the tone at low volumes, it is in the tone itself. 2x10's sound very
different from 1x12, at any volume, as do 2x12's. I personally prefer
the sound of two speakers to a single speaker, no matter what the
size. A friend of mine has the exact opposite opinion, he prefers a
single 12 over anything else. The speaker choice is up to the buyer,
some people prefer the tone of 12's, others prefer the tone of 10's. It
has nothing to do with higher or lower wattage rating, or any "speaker
smoothing". Different speakers have drastically different
characteristic tones. The buyer should choose the type of speaker he
prefers, it is as simple as that.
I have noticed no more "speaker smoothing" with a single, low-wattage
speaker than I have with multiple speakers. In fact, the Invader combo
absolutely kills at full attenuation when connected to a 4x12 cab loaded
with 30W speakers, a total of 120W worth of speakers - there goes your
single speaker theory.
Randall Aiken
http://www.aikenamps.com
Cybermonk
a 4x12 cab loaded with four 70-watt speakers (280 watts
capacity). By extreme, I mean the Hot Plate set to 16+ dB,
where the switch is set to 16 dB and the pot is set close to
infinity attenuation. The wretched sound in this condition
could be improved by focusing all that power into a single one
of those speakers.
Would a music store allow me to use the Power Brake or Hot Plate
to demo amps in the store? If so, that could be the solution to
the problem of "they won't let me crank the amp in the store for
a realistic demo". I will carry an attenuator in the car to
see. Isn't it odd that Guitar Center stores don't carry or
promote the Power Brake? If power attenuators are so great, and
power-tube saturation is so great, why don't guitar stores all
have a power attenuator hooked up to each amp, or have several
attenuators floating around the store just like spare picks or
guitar cables? Some people here might say "it's because power
attenuators kill the tone", but I don't believe it and my Hot
Plate and Power Brake demonstrate to me that having an
attenuator is far better than not having one available.
What is the worst, evil, tone-destroying power attenuator? The
Sholtz? (I heard there is an older and newer version.) I will
buy that and post A/B/C MP3 tests to prove that all standard
soaks work plenty well, when pushing the speaker reasonably well
such as -12 dB.
My rule about pushing just 1 speaker applies not to such loud
levels as -12 dB, the maximum attenuation of the Invader amp.
It applies to -16 dB and less, more like -30 dB on a 100 watt
head driving a 4x12 280-watt cab. I'm addressing a factor of
ten quieter than what many amp-blasting guitarists have in
mind. I'm addressing the t.v. level of playing, when using a
4x12 or possibly a 2x12 cab. This volume level is relevant for
a customer shopping in a music store trying to choose between a
modelling amp and a tube amp. The modelling amp sounds the same
at 250 mW as at 5 watts, but the tube amp sounds inferior at 250
mW reaching the speaker compared to 5 watts pushing the
speaker.
12 dB of power attenuation on a 15 watt amp is likely to be
louder than the common store-testing level of a modelling amp.
I have run my Blues Jr. Fender 15 watt amp into the Hot Plate at
12 dB attenuation and that's pretty loud when fully saturated.
The Hot Plate reaches down to 16 dB attenuation and then has a
pot to get down to near infinity, at which point the speakers
choke and fizz and sputter -- Andy Marshall agreed about this
when I told him of my first, awful sounding test of the Hot
Plate into a 4x12 cab that was probably loaded with high-wattage
speakers.
That's one of the many good features of the Hot Plate -- the pot
that applies to the 16+ dB attenuation setting. (It also has eq
switches and a pot-controlled Line Out jack, unlike the Power
Brake.)
The London Power: Studio has continuously variable output level,
I think, not a stepped switch.
The THD UniValve documentation doesn't say what the attenuation
amounts are. The amp has a single swappable power tube, so it's
low-wattage to begin with.
Lord Valve
with a guy who can't tell a phase-inverter from a fire
hydrant. That pig ain't *never* gonna sing... ;-)
LV
Cybermonk
attenuation. I played a used Ampeg VL-502 in the store and got
the best straight-into-the-amp/cab sound I've ever gotten in a
store at quiet SPL.
There are several models so it will take awhile to formulate the
queries and investigate. The new info/links page for this
series, designed by Lee Jackson, is:
http://www.amptone.com/ampegvlseries.htm
Twice so far, while investigating amps that have built-in power
attenuation, I've seen user comments wishing for a way to
control the attenuator setting via channel footswitch.
The VL-502 has a continuous Attenuation pot, not a stepped pot,
and has three transformers. The load resistors might be
fastened to the PC board.
Matt Seniff
<cybermon...@amptone.com.invalid> wrote:
>In a way, the guitar amp industry took a wrong turn in the early
>70s. Instead of adding the master volume feature to enable a
>kind of distortion at lower levels, they should have added power
>attenuation (whether through soaking away excess energy or
>restricting the power supply). Many people still want preamp
>distortion available as a controllable option.
Well I guess you were elsewhere then because what sold amps in the
70's was high power specifications. Most guitarists figured more was
better (with some few exceptions). Small amps in general only sold as
practice amps and there was no " awful white-boy blues scene" like
there is today. The average bar band was a volume battle between the
players. You brand of low powered saturated amps could not have been
given away since home studios were pretty rare and very pricy by
today's standards. Hell PA's in most place were barely able to boost
the vocals to audibility let alone amplify electric guitars or drums
so you had to have a loud amp to be heard at all.
>Very few amps have power attenuation built in.
Extra features cost extra dollars and the bottom line is competitive
pricing. The average guitarist today can't even grasp the idea of too
much power let alone a power attenuator. IMHO attenuators may be okay
in a poorly designed studio but they tend to remove some of the most
desirable artifacts like the speakers breaking up and micing effects
(like the SM57 clanks we all love so dearly).
>THD announced the Uni-Valve amp at the same NAMM as the Hot
>Plate, and ended up putting the Uni-Valve on hold until now.
>
>The Koch Twintone amp and some others have power attenuation but
>only a couple steps.
>
>London Power provides power-supply-based power attenuation.
>
>Maven Peal implies that their attenuation is power-supply based
>as well.
>
>The Guytron doesn't have a power attenuator; the mid-stage tube
>power amp is run into a full dummy load, then a conventional
>tube power amp brings the level back up to push the speakers.
>Same with the Rail Rocket design at ax84.com.
>
>The JayTronics Tru-Tone 2-watt tube amp has built-in power
>attenuation "enabling full power-valve saturation down to a
>fraction of a watt, without degradation of tonal qualities".
>
>The Jim Kelley FACS 112 amp was packaged with an outboard power
>attenuator.
Well unfortunately (for me at least) it just isn't great for live
playing or even band practice. The use of a power attenuator takes to
much of the "snap, crackle and pop" away and leaves a flat tone that
tends to disappear when there are several players. I have over the
years played around with a lot of these same ideas and found them of
little use for a band application. As for recording I knew I was going
to have a studio and practice space and picked my house out
accordingly with a large, dry, pleasant basement space. I also talked
to the neighbors before I bought the house (one side has my garage and
the neighbors between us and the other side has people that make as
much noise as me (even with the full band playing it is no louder than
a lawn mower on the front yard).
>What are the pros and cons of outboard versus built-in packaging
>of a power attenuator? That's a question like preamp distortion
>integration. An integrated power attenuator could enable better
>integration and ease of use, including ease of transport. There
>are various ways to integrate the power attenuator. The Invader
>provides a convenient, elegant control on the front of the amp,
>and a heavier power transformer that assumes pushing the tubes
>to full power continuously.
>
Cons: uses up tubes more quickly. Introduces more heat into the
electronics which will result in more failures over time. Gives a
densely compressed tone not necessarily applicable to anything but
hiding in ones basement or one recording tone.
>It's ironic that tube amp purists often end up adding a
>distortion pedal before the amp and a power attenuator
>afterwards
A distortion pedal is a convenient and desirable way to get a second
sound by just turning it off or on. You could actually play a clean
rhythm part then step on the distortion pedal to get a nice distorted
lead sound. What a concept! DOH!
> -- this is like going with a modular, rack oriented
>approach as opposed to an all-in-one approach -- especially if
>you use a separate head and cab. You could string the products
>out across the floor:
>dis/od pedal
>purist, simple, elegant vintage head
>power attenuator
>cab
>
>That's four pieces of gear. Would we rather have just one? An
>amp with od/dist onboard, and of course a tube power amp, and a
>built-in power attenuator, in a combo cab.
No because with external distortion pedals I can have two or more set
for different purposes (or even turn on two or more at once when
needed).
>I think the Power Brake with inductive load has slightly more
>dynamic depth and roundness than the resistive Hot Plate load.
>But the Power Brake is twice the height and weight of the much
>better looking Hot Plate. The Hot Plate is more transportable.
>The Power Brake is like a very large brick. With outboard
>attenuators you have to buy additional cables and take the time
>to hook them up.
I have used both along with the Altair (as well as one of my own
design) and was pretty under whelmed for the most part. To me the most
reasonable use was at low levels of attenuation in a band situation
but it still made the transitions from clean to lead a little dicey
for me.
>Info/links for these are at http://www.amptone.com; search the
>home page.
I guess some of these little tricks are okay if all you do is noodle
in you bedroom but at some point you need to play with others. Music
is communication at a very basic level and the communication inside a
band is the real deal. Unfortunately low volume cranked tone will
totally disappear in a band setting unless you mic it up then you have
a very squashed lifeless tone coming thru the monitors (yuk!!!).
>If someone buys the Invader to obtain private cranked-amp tone,
>shouldn't they order the 1x12 version rather than the 2x10 or
>2x12 version? The lower the total wattage rating of the speaker
>system, the more speaker smoothing you will obtain at the 1 watt
>level. For a tube amp with a lot of flexibility of venue, it
>could have two low-wattage speakers, and a switch to disconnect
>one for the living room or coffeehouse or bookstore gigs.
This would result in an impedance mismatch between the speakers and
the output stage resulting in a deterioration of tone and depending on
design damage to the amp.
>Bookstore gigs are not unusual. The chain bookstores with audio
>sections like to have live music including rock guitar. Tube
>amp makers *can* address this venue and do not have to concede
>this market to the modelling amps.
You don't always have to have a totally saturated tone to play do you?
IMHO variations is the spice of life and a change is good for you
artistically, a different tone can lead you to different places
musically and make you think a little more (sorry for that particular
bit of heresy). Try playing a nice old Twin Reverb clean sometime it
can be a wonderful learning experience (sure makes you clean up your
chops). matt
Cybermonk
At
http://firebottle.net/chatfiles/log_ampage/Mon22May2000.html
RA wrote:
>That's the idea ... I want to build the amp Marshall *should*
have built. [Lee Jackson] put in a control
labelled "attenuator", which was just a post-PI, cross-line,
single-pot, master volume (in addition to the existing pre-PI
master!). My friend thought he paid for a "real" built-in
attenuator. A real pity. ... You put a 1M pot across the output
side of the phase inverter coupling caps. It shorts the two
phases together, and reduces the volume. ... Sounds like hell at
low volumes. Matchless did the same thing on their amps.
Cybermonk
Many people are happy with using a power attenuator for a gig.
It's clear that opinions on power attenuators are all over the
map. People report completely contradicatory findings. My own
experiments have provided contradictory results about the
potential of power attenuators.
o Many people have a power attenuator, love it, use it at home
and at gigs, and consider it a necessity. Some of these people
are Tone and vintage amp enthusiasts.
o Many people report that power attenuators in general suck the
Tone significantly.
o Some people say that certain attenuators sound great and
others sound bad.
o Other people seem to consider attenuator models to be pretty
much equivalent.
Some people report burning out the output transformer with
supposedly inferior power attenuators, typically the Power
Soak. Other people report using the Power Soak for ten years
with a cranked head, with no problems.
It's good that the output transformer of the Invader can handle
twice its rated power. This is one advantage of 15- or 20-watt
amps as opposed to 50-watt amps: lower stress on the output
transformer.
Lately I've used a combination of power attenuator and speaker
isolation cabinet. I do agree that the speaker itself sounds
better and more dynamically rich when pushed near its rated
power. I don't word this as "the attenuator compresses the Tone
and sucks the Tone away", but rather, "speakers sound better
when pushed hard."
Aiken claims that the Invader has a superior attenuator that
doesn't suck Tone away. Some people have already concluded that
all attenuators suck the Tone away too much. Some people say or
impy that running a 5-watt amp into a certain cab sounds better
than attenuating a 50 watt amp to 5 watts and then pushing that
same cab.
One variable-SPL approach for those who are averse to
attenuators is to put a 5 watt and 50 watt amp into one head,
sharing components as much as possible. July 2000 Guitar Player
magazine has a short article about an amp along these lines.
I suspect that people running 4x12 cabs with high-wattage
speakers are more critical of attenuators that people who run a
single low-wattage speaker. If you push a 4x12 280-watt cab in
a bedroom, I'd expect you to emphasize that an attenuator is
only good for a few dB attenuation but then sucks Tone too much.
It's too broad a generalization to say that low-SPL or variable-
SPL tricks could be effective for at home but don't apply well
to gigging situations.
It's plausible that the *very best* tone comes from a tube power
amp directly driving speakers, with no power attenuator getting
in the way. But the debate about the potential of power
attenuation has to do with *what degree* of Tone compromise
results. If you can reduce the SPL to half the perceived volume
with just 3% degradation of Tone, that's close enough for rock
and roll, and is a God-send. If there is a 25% degradation of
Tone, however, that is more of a concern.
There is great disagreement, which should be turned into a
debate, about what degree of degradation arises, and whether
certain approaches to power attenuation, such as the Invader's
approach that is advertised as not reducing the Tone, are better
than others, such as the often-maligned resistive Scholz Power
Soak.
Why will the Invader's attenuation satisfy those who dismiss all
attenuation as sucking Tone significantly? The Invader uses
conventional placement of the attenuation; its attenuator soaks
excess power and is positioned after the output transformer,
unlike the London Power Power Scaling approach.
Randall Aiken, Maven Peal, and Kevin O'Connor are all online,
and write in a cooperative way, and I would sure love to see a
discussion among them of the pros and cons to various power
attenuation approaches.
Which approach will satisfy most of the critical players who
currently maintain that power attenuation sucks Tone
significantly? Some customers will dismiss all forms of
attenuation, and some customers will declare all forms a
complete success. Which approach sounds the best, and how much
potential does it have? This is an important topic that needs
more coverage and industry awareness.
Like GM Arts (below), I wonder why power attenuators aren't far
more popular. The Guitar Center store doesn't even carry them --
though I snapped up a used Power Brake there (and Jim Marshall
signed it), and I am completely pleased with it. I'll say this
much: everyone who wants the freedom of variable SPL should
definitely try out more than one combination of soak, head, and
cab. Especially, use a low-wattage cab when attenuating heavily.
http://www.chariot.net.au/~gmarts/pickifaq.htm
>But many of us play in several bands (or unstable bands!), and
in many different venues from outside to restaurants. The
common solution to the need to get good to great tones at any
volume is to have a medium to high power amp (50 to 100 watts),
and when you can't wind it up to the volume you like, to use a
clean amp tone with an overdrive pedal for similar, but less
satisfying tones.
>Another possibility is to use a speaker load, such as the
Marshall Power Brake. These allow you to still overdrive the
power amp of your Marshall, where the good overdrive sounds
are. For some reason, these devices aren't terribly popular;
I'm not sure if its the loss of that Marshall "thump in the
chest", or the loss of feedback induced sustain that is
perceived as a loss of tone. Whether you go down the stompbox
or speaker load path, I suggest you try before you buy.
Danny Russell
Cybermonk wrote:
>
> We need more coverage and discussion of power attenuators.
SNIP
> o Many people have a power attenuator, love it, use it at home
> and at gigs, and consider it a necessity. Some of these people
> are Tone and vintage amp enthusiasts.
>
> o Many people report that power attenuators in general suck the
> Tone significantly.
SNIP
The only important thing to know about attenuators and tone is that
they undeniably DO tend to flatten the sound and feel of an amp.
Whether that results in a good or bad ending is completely
subjective (just like anything else regarding tone). Some amps may
benefit from a little tonal flattening. -Danny
--
<<<GET BLITZED!!!>>>
http://home.flash.net/~blitz/tunes.html
To get inside my whacky head.
Cybermonk
detail. There is enough to write a power attenuation FAQ.
POWER ATTENUATOR FAQ
A power attenuator reduces dynamic depth to some degree.
There is some debate about how significantly an attenuator
flattens the dynamic depth.
It is not uncommon for use of a power attenuator to result in a
blown output transformer or power tubes. These breakdowns might
be caused by using a resistive load, but blown OTs have also
been reported when using the reactive Marshall Power Brake with
a Marshall head (and Marshall has been known to replace such OTs
under warranty). The ability to push the amp so hard yet
quietly encourages pushing the amp past its natural limit, in
which case the amp would have blown up anyway even when driving
an actual cab at that level of output-stage saturation.
If you drive 280 watts worth of speakers with 60 mW, it will
sound thin and fizzy. This is not the fault of the power
attenuator; the speakers aren't designed to respond correctly
with such low wattage. Try reducing your cab wattage capacity
when attenuating down to the milliwatt (TV) level.
As with any equipment, different attenuators sound different.
Listen to several combinations of attenuator, cab, and head, to
decide which attenuator models you like best.
There are several categories of power attenuator:
Resistive
Reactive (R/L/C) - with a transformer as the inductor
Sand-box resistors
Toaster-coil resistors
Power supply reduction with bias compensation
Post- phase inverter, cross-line pot, such as a 1M pot across
the output side of the phase-inverter coupling caps.
You can make your own power attenuator; in fact this is one of
the most useful, easy, and inexpensive DIY projects.
(http://www.amptone.com/g243.htm)
Be careful to provide safe heat dissipation; don't melt your
amp's covering.
You should understand the logarithmic relation between wattage
and perceived volume.
http://www.amptone.com/g112.htm
Power attenuators are packaged in several formats: rackmount,
amp-top, built into the head. They are often packaged with two
closely related circuits or features: a cabinet simulation
filter, and a full dummy-load ability.
A power attenuator can be thought of as two components: a dummy
load and a variable wattage-splitter control. This is clearest
with the Kolbe The Attenuator and the Kolbe Silent Speaker. The
Silent Speaker is the dummy load (and line-level tap), and The
Attenuator is the variable wattage-splitter control. You can
use a muffled cab as the dummy load instead of a built-in
resistive or reactive load, but the monitor cab will still
suffer some loss of Tone as it is pushed less.
Some power attenuators only have a couple of steps, such as half
and quarter power. Others have many incremental steps, and some
alternative approaches have a continuous pot. So far, no power
attenuator is MIDI-controlled, but that would enable switching
from a loud clean power-amp sound to a quiet, saturated power-
amp sound.
A power attenuator setting does not cause output-stage
saturation or change the amount of output-tube saturation; it
enables output-stage saturation at quiet SPL in the room. There
are three kinds of volume controls when using a power attenuator
in a standard setup. The first ("gain") controls the amount of
preamp distortion. The second ("master volume") controls the
amount of power-tube saturation and output transformer
distortion. The third ("attenuation") controls the amount of
power sent through to the speakers, as opposed to being sent to
the dummy load; this controls speaker distortion and room volume
level.
Related approaches for getting power-tube saturation at variable
SPL are low-wattage amps, pulling tubes, changing from pentode
to triode operation, cascading power tube/dummy load stages,
multi-wattage amps, speaker isolation cabinets and cabinet
isolation boxes, and coneless or muted speakers.
Specific power attenuator products are described at
http://www.amptone.com/guitaramptable.htm.
--- end of power attenuator FAQ ---
Will the Invader add anything to this FAQ -- new approaches or
techniques? Is any other information needed for a FAQ?
Cybermonk
http://www.harmony-central.com/Guitar/Data/Bogner/Ecstacy-01.html
Has a dedicated loop for a power attenuator (channel assignable).
Cybermonk
and a power-tube saturation channel with a power attenuator.
http://www.amptone.com/g176.htm - some info/links about FACS
Cybermonk
http://www.amptone.com/powerattenuatorfaq.htm
Also look for "attenuator" on the Home page and the News page.
Especially after checking my results by reading so much Web
commentary, I think the main trick in getting good sound with
heavy (16 dB) attenuation is to use a single low-wattage speaker
and push it to at least 1 watt; don't push 8 150-watt speakers
(1200 watts worth) at midnight bedroom jamming levels (50 mW)
and expect the speakers to sound decent.
Some Fender amps were designed to protect the speaker from
blowing by having an undersized output transformer. Running a
power attenuator on such an amp is likely to blow the OT.
That's why it's great the Aiken Invader amp has a heavy-duty OT
designed for sustained use with the built-in power attenuator.
http://www.victoriaamp.com/tonequest.html - "In the mid 50's,
the speakers used by Fender were Jensens, and if you take a look
at the specs of a P15N for example, it was an 18W speaker. A
P10R is rated at 9W or 10W and that's a critical factor in
relation to the transformers that were used. I was fortunate to
acquire the actual engineering data that was used to manufacture
the original transformers from a retired engineer that had
worked at Triad, and he had kept the original winding data.
On these sheets where the specs are listed, one of the criteria
for the transformers used for the tweed Pro, Bandmaster, and
Super was that the transformers be built with "restricted low-
frequency response." What this means is that they were trying
to restrict low frequencies getting to the speaker, because
those are the frequencies that will blow a speaker the fastest.
So they were using a smaller transformer then what you would
have expected for the tubes that were being used, because the
way to restrict low-end is to diminish the size of the
transformer core. So I think Leo Fender wanted to saturate the
transformer before the speaker became saturated, but as players
were turning up these amps and getting great saturated tone,
they were also saturating the transformer, and probably a lot of
heat was generated that over the years, caused them to fail. Of
course, it would have taken just a few weeks to cause the
speakers to fail."
Dave
check out the Cruise MQ4 and see how they did power selection?
I think that they have the right idea about power selection,
although it isn't switchable "on the fly". Of course, tubes and
power selection are never going to be switchable on the fly due
to the incredible transients involved with switching plate
voltages and whatnot. I've heard the MQ4 through a full stack
at 5W, and it was thick...
Dave
Cybermonk
5 watts instead of pushing 8 speakers at 5 watts total? The
magic wattage-per-speaker ratio I'm asking people to consider
works out in those setups to 5 watts per speaker vs. 625 mW per
speaker. Any one speaker will sound better if pushed by 5 watts
than by 625 mW. If one of the speakers you heard produced good
Tone when pushed by 625 mW, consider how much better it would
sound if pushed by 5W. That, I think, is what people are
talking about when they say that power attenuators suck Tone
away.
Thanks, the Cruise MQ4 is the one amp I lost at my site. I
wanted to include it in the list above but couldn't remember the
name. I should group such amps into a new section
called "Variable-Wattage Amps", and promote that concept,
covering multi-wattage tube amps that can saturate at under 20
watts in their lowest range.
http://www.amptone.com/g225.htm -- info/links for the Cruise MQ4
5-100 watt amp -- "Wattage Selector: the final stage (or is it
the beginning stage?) is the Wattage Selector control. Don't
confuse this control with one of those power attenuators on the
market--you know, the ones that limit the amount of energy sent
to the speakers--because this 8-position control actually
changes the output of the power amp stage.
You know [the unprecedented flexibility of this amp's] stock
channels, tone, gain, and Blend? Well, multiply all that you
can do with those functions by a factor of eight. Why? Because
each of the Wattage Selector positions alters the tonal spectrum
of the MQ4. [odd, usually you want wattage change to not affect
Tone.] The eight positions are 100, 65, 50, 35, 25, 15, 10 and
5 watts. To make this amp even more versatile (like it needs to
be!) the 50, 15 and 5 watt positions are Class "A".
Just as important is how the power amp is designed (not just the
fact that it uses 4-EL34's). The power transformer is a superb
Toroid transformer that is used not only as the main power
source but also to provide the taps necessary to accomplish the
radical Wattage Selector switch. Coupled with the power of the
preamps our power amp helps us give you tones from pristine, to
the scorch of metal and ALL points in between."
So they are doing something comparable to London Power --
reducing the supply voltage for the tube power amp. This is
related to plugging an amp into a 110 volt mains supply and
setting the supply switch on the head to 220 volts; a different
tap of the supply transformer is used.
I've always thought it is a better idea to generate less power
in the first place rather than produce full power and then
discard a portion of it -- saves tubes, too. However,
generating less power would eliminate output transformer
distortion, for what it's worth.
After we see enough amps with variable wattage, we might see
more interest in channel-switching control of the wattage
setting.
Matt Seniff
<cybermon...@amptone.com.invalid> wrote:
>Would the MQ4 have sounded even better pushing just 1 speaker at
>5 watts instead of pushing 8 speakers at 5 watts total? The
>magic wattage-per-speaker ratio I'm asking people to consider
>works out in those setups to 5 watts per speaker vs. 625 mW per
>speaker. Any one speaker will sound better if pushed by 5 watts
>than by 625 mW. If one of the speakers you heard produced good
>Tone when pushed by 625 mW, consider how much better it would
>sound if pushed by 5W. That, I think, is what people are
>talking about when they say that power attenuators suck Tone
>away.
No what most people are referring to is the lack of
interaction between the output amplifier circuitry and the speaker. A
power attenuator (particularly when large amounts of attenuation are
in use) interrupts this interaction. A speaker is really a little
motor made up of a permanent magnet (usually) and a voice coil, as we
all know current flowing thru the voice coil will cause a magnet field
to develop and makes it move in relation to the stationary permanent
magnet and thus produces sound by causing the cone to move along with
it. However when the voice coil moves inside the magnetic field it
will produce a voltage across it self since a speaker can also act
like a generator as well as a motor (this occurs even when it is being
used normally) in fact this is how a dynamic mic works. These self
generated voltages enter the feedback loop of the amplifier and
produce some very complex interactions. When you couple that with the
impedance variations of a speaker across the used audio bandwidth (and
they can be huge variations if you actually graph them) you get the
real tone of a cranked or clean amp. When you apply a power attenuator
you also attenuate these interactions.Many power attenuators are made
reactive to try and match the impedance vs frequency variations but
adding an inductor and some capacitors will only reproduce the
impedance curve (and not very closely at that) giving an approximate
equivalent "tone control" but the power amp/speaker interaction is
severely impaired. This is why I pretty much have found power
attenuators to be useless for me.
Now here's a little bonus for you: What do you do with the
unused speakers in the cabinets above? I have found that any
unconnected speaker sitting in the vicinity of a powered speaker will
sympathetically reinforce the working speaker. In fact when
disconnecting a spkr in a combo amp the volume will decrease less than
you think unless you short the voice coil of the unused speaker (it is
a very audible difference). A very good example of this are the
speaker switching boxes in hi-fi shops the good ones will short the
voice coils of all non-auditioned speakers. The really good shops
(honest) will have the shorting type of speaker switchers the crappy
ones won't and the difference in a speaker showroom is nothing less
than dramatic. So for low volume cranked tone unconnected speakers are
a big step in the wrong direction. matt
Cybermonk
testing is the only way to determine the potential of a setup
such as:
50-watt amp
reactive power attenuator
25-watt speaker
Enough claims, now upload MP3 samples so we can hear it for
ourselves. In the future, the Web will enable us to share our
tests and experience, providing sample clips to go along with
our assertions and reports.
Would shorting a disconnected speaker reduce its sympathetic
movement, compared to leaving its coil ends disconnected?
Shorting it would enable current to flow through the coil in a
loop as the speaker sympathetically vibrates.
Another option is speaker blocking and coneless speakers.
I would like to hear how much bass you can get from an
inefficient 8" speaker in a 2x12 closed-back cab.
The most authoritative cranked-amp Tone requires saturating
power tubes directly interacting with a hard-driven speaker
through an output transformer, with nothing getting in the way.
The load (speaker, resistor, R/L, or a mix) affects the signal
at the amp's Spk Out jack -- both the frequency response and the
dynamics.
http://www.two-rock.com provides the Amethyst Special, covered
in July 2000 Guitar Player magazine. The magazine (unlike the
site) says the amp has a 6V6 "preamp" and a 6L6 final amp. When
the 6V6 amp is used as a preamp, it's implied that the 6V6
drives a full dummy load, like the Guytron amp and AX84.com Rail
Rocket. The 6V6 amp can directly drive an 8" speaker in the
combo. The 6L6 amp drives a full-size speaker in the combo.
This is similar to the Lexicon Signature 284 2x3-watt amp used
in a channel-cascading approach. The Guytron approach or EVH
approach enables some interesting sounds at any volume level.
This forms essentially a power-tube saturation pedal, which is a
good tool to have in our distortion toolbox.
As far as the channel-switching ability with a 3-stage Guytron
configuration, there should be a way (footswitch) to bypass the
mid-stage power-tube saturation, just as a head with 5 preamp
gain stages should have a footswitch and clean channel with just
2 preamp gain stages.
EVH's use of a head into a load resistor was for stage -- I have
not heard anyone assert that the sound on VH1 album is a head
driving a load resistor (then final amp and guitar cab). It
might or might not be.
Crossfire
I just want to give you an unsolicited public "Thank You" for the great
service I received on the recent amp-parts order I placed with you.
Immediate response, good prices and quick delivery. You can consider me a
very satisfied customer.
Jeff Ford
--
CROSSFIRE...Classic Rock 'n Roll
http://www.Crossfire.rocknrollband.com
Randall Aiken
Crossfire wrote:
Thanks, Jeff! I'm glad the parts arrived safe and sound.
Randall Aiken
http://www.aikenamps.com
Paul Cornford
of july due to the death of a dear friend and great player,our
minds were rapped up with the loss and not with selling
stuff,your email has now been answered.
Cybermonk
of non-response was true. A company gets high marks with me for
having a complete online presence, since I live online and rely
on online research and discussion to pull together my guitar-
gear information site.
Best wishes.
I hope you continue an active presence online, and hope to
discuss pros and cons of various designs.
http://www.amptone.com -- info/links for low-wattage amps and
variable-wattage amps