Tone and volume controls for a piezo preamp?

[Tony Done]

I have a simple Martin Matrix piezo preamp and couple of Schatten bug
piezos that seem to work OK through it. How would I add passive tone and
volume controls? On the input or on the output side? I measured the
resistance, and it was off the scale (more than 20M) on the input, and
about 100K on the output side. Any suggestions for pot and cap values?

Thanks.
--
Tony Done

http://www.soundclick.com/bands/default.cfm?bandID=784456

http://www.flickr.com/photos/done_family/

[RS]

On Thu, 24 Oct 2013 12:21:55 +1000, Tony Done <tony...@bigpond.com>
wrote:

>I have a simple Martin Matrix piezo preamp and couple of Schatten bug
>piezos that seem to work OK through it. How would I add passive tone and
>volume controls? On the input or on the output side? I measured the
>resistance, and it was off the scale (more than 20M) on the input, and
>about 100K on the output side. Any suggestions for pot and cap values?
>
>Thanks.

Hi Tony,

You'd probably want to add the controls on the output side. Piezo
pickups are -very- high impedance, as you have noticed. It's more
difficult to scale tone circuit components, especially given the
reactive nature of piezos.

Also, you can't always tell impedance from doing power-down resistance
measurements. I wouldn't doubt that the actual output impedance is
lower than 100k.

Your post implies that you don't have volume controls in place, right?
If you can dig up some tech info on the Martin Matrix, I may be able
to work out a circuit for you.

[Tony Done]

Thanks RS. I haven't been able to find any tech info. It is the old
Matrix Natural preamp, a little black box that sat on the end of the
endpin jack, no controls of any kind.

[Desk Rabbit]

On 24/10/2013 03:21, Tony Done wrote:
> I have a simple Martin Matrix piezo preamp and couple of Schatten bug
> piezos that seem to work OK through it. How would I add passive tone and
> volume controls? On the input or on the output side? I measured the
> resistance, and it was off the scale (more than 20M) on the input, and
> about 100K on the output side. Any suggestions for pot and cap values?
>
> Thanks.

You need one of these:
http://www.orchid-electronics.co.uk/acoustic.htm

or these
http://www.fishman.com/products/filter/type:preamps

[RS]

On Thu, 24 Oct 2013 14:36:14 +1000, Tony Done <tony...@bigpond.com>

wrote:

>On 24/10/2013 1:01 PM, RS wrote:
>> On Thu, 24 Oct 2013 12:21:55 +1000, Tony Done <tony...@bigpond.com>
>> wrote:
>>
>>> I have a simple Martin Matrix piezo preamp and couple of Schatten bug
>>> piezos that seem to work OK through it. How would I add passive tone and
>>> volume controls? On the input or on the output side? I measured the
>>> resistance, and it was off the scale (more than 20M) on the input, and
>>> about 100K on the output side. Any suggestions for pot and cap values?
>>>
>>> Thanks.
>>
>> Hi Tony,
>>
>> You'd probably want to add the controls on the output side. Piezo
>> pickups are -very- high impedance, as you have noticed. It's more
>> difficult to scale tone circuit components, especially given the
>> reactive nature of piezos.
>>
>> Also, you can't always tell impedance from doing power-down resistance
>> measurements. I wouldn't doubt that the actual output impedance is
>> lower than 100k.

>Thanks RS. I haven't been able to find any tech info. It is the old
>Matrix Natural preamp, a little black box that sat on the end of the
>endpin jack, no controls of any kind.

Hi Tony,

Yeah, I just took a quick look and didn't see any definitive specs on
the Matrix. Have you ever looked inside the box? May as well, since
you'd need to gauge how much space is available for mounting controls.

If you want to be (slightly) methodical about it: Hook up the preamp
as normal. Now hook just two terminals of a 250K or 500K pot between
the signal and ground wires. Turn the pot down until you hear a
change in sound. Then disconnect it and get me the resistance reading
between those two terminals.

Or if you want to try a quick fix that will probably work OK, just
hook up a 250k audio taper pot (like a Fender control) to the output
to see if you're OK with the sound and operation. I'm sure you know
the drill: Guitar output to the 'top' terminal, output to amp from the
middle terminal, and grounds from both connected to the lower
terminal.

Also let me know what you're looking for in the tone control. It's
difficult to get rid of piezo quack, if that's what you'd after. But
it's possible to structure the corner frequencies of the rolloff so
you can affect highs without cutting out too much of the mids.

A third question: If you're looking for 'dark', would you want to
include either a switch, or maybe use a dual-ganged pot for more
efficient rolloff of highs.

I'll figure out a tone circuit from the info that you get re the
volume pot and how you want the tone to work.

[Tony Done]

OK, I put a B25K pot across the output as a straight resistance as you
suggested, and it started to reduce the volume at about 12K.

The controls don't have to go inside the little box, they will go on the
guitar, probably mounted on the reso coverplate. Piezo quack isn't such
a problem with nylon strings, and the quick tests I did with this set up
(preamp, two Schatten bugs in parallel) jury rigged on a flattop
indicated that it isn't very quacky anyway

[Tony Done]

I'm trying to put together an internal preamp from parts I have on hand.
If I was going for an external preamp it would likely be a Red Eye.

[benj]

On 10/24/2013 08:19 PM, Tony Done wrote:

> OK, I put a B25K pot across the output as a straight resistance as you
> suggested, and it started to reduce the volume at about 12K.
>
> The controls don't have to go inside the little box, they will go on the
> guitar, probably mounted on the reso coverplate. Piezo quack isn't such
> a problem with nylon strings, and the quick tests I did with this set up
> (preamp, two Schatten bugs in parallel) jury rigged on a flattop
> indicated that it isn't very quacky anyway

A 25K pot across the output with the center terminal going to the output
jack should work though 25K may or may not be a bit low. I'd have to see
the preamp circuit to be sure. The problem with this is that the pot
tends to raise the output impedance which is held low by the preamp
cable driver. That then means that long cables will have more tone suck
than without the control.

The alternative (which I've done) is to put the pot at the piezo. Piezos
need VERY high impedance or you loose low frequencies. On a guitar 1 meg
is about as low as you can go. 10 meg is ideal (especially since your
preamp seems to have no loading resistor). Pots in these values are
harder to come by but you can get them. The outside terminals of the pot
go to the pickup and the slider (center terminal) goes to the preamp
input. That makes a volume control.

As for tone, I'd try that on the piezo side as well. Again use a 5 or 10
meg pot and you'll have to experiment with capacitors (note it will be
SMALL!) to get the sound you want. Just connect across the piezo pickup
and see what happens. It would probably work best if the tone pot were
10 meg and the volume 5 meg.

I wired one of my resos with piezo and magnetic pickups and I used 1 meg
pots and it's the limit. It loses some lows but in this case the piezo
was to supply the highs and the magnetic the lows so it worked out great
and made the guitar passive so no battery was needed. My other reso was
setup the same way but I used an active "powerchip" by Fishman. Kind of
expensive but did a great job of matching piezo, mixing in magnetic and
driving cable. But takes a battery.

Good luck!

[Neil Gould]

benj wrote:
> Piezos need VERY high impedance or you loose low frequencies. On a
> guitar 1 meg is about as low as you can go. 10 meg is ideal
> (especially since your preamp seems to have no loading resistor).
> Pots in these values are harder to come by but you can get them. The
> outside terminals of the pot go to the pickup and the slider (center
> terminal) goes to the preamp input. That makes a volume control.
>
> As for tone, I'd try that on the piezo side as well. Again use a 5 or
> 10 meg pot and you'll have to experiment with capacitors (note it
> will be SMALL!) to get the sound you want. Just connect across the
> piezo pickup and see what happens. It would probably work best if the
> tone pot were 10 meg and the volume 5 meg.
>
> I wired one of my resos with piezo and magnetic pickups and I used 1
> meg pots and it's the limit. It loses some lows but in this case the
> piezo was to supply the highs and the magnetic the lows so it worked
> out great and made the guitar passive so no battery was needed. My
> other reso was setup the same way but I used an active "powerchip" by
> Fishman. Kind of expensive but did a great job of matching piezo,
> mixing in magnetic and driving cable. But takes a battery.
>

+1

I did a very similar thing when I revised the Neil/Armstrong circuit to
eliminate the batteries (Dan Armstrong + Neil's various mods; the piezos are
ST1s, likely predecessors to the Ghosts since they are the identical form
factor). I was rather limited in pot choices because I needed dual
concentrics, but the 1m volume worked out, and blends well with the
magnetic.

Question: why such a high value pot for the tone? Mine is only 250k, but
seems to have a bit of range with few consequences. I'd think the capacitor
would make more of a difference.
--
best regards,

Neil

[Tony Done]

And Benj. This is a bit OT, but might interest you. I found a few months
ago that you can combine a piezo and magnetic by putting the magnetic
*in series* with the output from the piezo preamp. I did this from the
Maton AP4 preamp and added a phase switch and volume control to the
magnetic. There's a pic of it about 10 back from the top of my Flickr
page (below) as a soundhole pickup with the push/pull pot for phase and
volume stuck on the bottom of the pickup. It looks pretty ugly, but it
it didn't seem to be suffering any signal loss from either the piezo or
magnetic, when either was used on its own. The preamp also had tone and
volume controls, so I had a lot of control over the output options. What
I found most interesting was that the magnetic worked even if I pulled
battery from the preamp, again apparently without any noticeable loss of
signal from the magnetic. I should have checked the resistance across
the preamp to see what was actually in series with the magnetic, but I
didn't, alas.

I tried a quick jury rig of this with the Martin preamp discussed in
this thread, and it appears to work in the same way as the AP4. -
However, I didn't try it in a guitar, just by some tap testing.

I have a 1M pot so I'll see how it works on the input side of the
preamp, but I doubt I will be able to get a 10M pot anywhere in town.

[RS]

If you're worried about 'tone suck' from the relatively low impedance
volume pot feeding the cable, then aren't you also concerned with the
large value pot on the piezo? The piezo will ideally want to see
something much larger than 1M (or the loading will change the sound).
At that point, you have series resistance working again residual
capacitance on the preamp input. Again, all fine if that's the sound
you want.

As for driving the cable thru the output pot, keep in mind that the
series resistance of the pot itself will be at max when the pot is at
1/2. So you have two 1/2 pot-value resistors in parallel. That
amounts to 1/4 of the value of the pot. For a 50k pot, for example,
it would add only about 12.5k.

[RS]

On Fri, 25 Oct 2013 10:19:18 +1000, Tony Done <tony...@bigpond.com>

So the actual output impedance of the preamp is probably in the
neighborhood of 5k to 10k or so. That's enough to work with. You
could go with a 50k pot or maybe even the 25k that you used for the
test.

>The controls don't have to go inside the little box, they will go on the
>guitar, probably mounted on the reso coverplate. Piezo quack isn't such
>a problem with nylon strings, and the quick tests I did with this set up
>(preamp, two Schatten bugs in parallel) jury rigged on a flattop
>indicated that it isn't very quacky anyway

If you're going to try the piezo-side pot that Benj suggested, then
maybe do a quick test. Jumper a resistor across the piezo to see if
you like the difference in sound. I believe that you will hear that,
but maybe you'll prefer the tone of the loaded piezo.

Then if you decide you want to go with the down-stream circuit, I'll
do one o' them fancy ascii schematics for you.

[benj]

On 10/25/2013 04:14 PM, Tony Done wrote:

> And Benj. This is a bit OT, but might interest you. I found a few months
> ago that you can combine a piezo and magnetic by putting the magnetic
> *in series* with the output from the piezo preamp. I did this from the
> Maton AP4 preamp and added a phase switch and volume control to the
> magnetic. There's a pic of it about 10 back from the top of my Flickr
> page (below) as a soundhole pickup with the push/pull pot for phase and
> volume stuck on the bottom of the pickup. It looks pretty ugly, but it
> it didn't seem to be suffering any signal loss from either the piezo or
> magnetic, when either was used on its own. The preamp also had tone and
> volume controls, so I had a lot of control over the output options. What
> I found most interesting was that the magnetic worked even if I pulled
> battery from the preamp, again apparently without any noticeable loss of
> signal from the magnetic. I should have checked the resistance across
> the preamp to see what was actually in series with the magnetic, but I
> didn't, alas.

I presume if you put it in series you have to use a high input impedance
preamp for the whole thing. On my passive Reso I do remember using a 1
meg pot and found that 10 megs were nearly impossible to find, but some
2 meg and 5 megs do seem to be around. On the resos, I just hack a hole
below the neck for a pickup but on another guitar (I think it's my Carlo
Robelli 12 string) I have a sound hole pickup very much like yours and a
piezo glued with silicon bathtub seal under the top by the bridge. For
mine I "crafted" a nice piece of maple to hold the pickup and mount it
in the sound hole. I used a vintage DeArmond Silertone pickup (got
several at a guitar show for a song...love them)
That guitar is wired passive like the reso with magnetic volume and tone
as well as piezo volume (the 1 meg pot). To tell the truth I don't
remember how I wired them. I'd have to look inside to see. But they work
very nicely.

> I tried a quick jury rig of this with the Martin preamp discussed in
> this thread, and it appears to work in the same way as the AP4. -
> However, I didn't try it in a guitar, just by some tap testing.
>
> I have a 1M pot so I'll see how it works on the input side of the
> preamp, but I doubt I will be able to get a 10M pot anywhere in town.

It's hard to deal with these two levels of impedance plus the fact the
most amps have an input about a meg or lower. But even though my guitars
are less than optimum, you can use the controls to dial in a pretty good
tone without any fancy preamps. My Spider reso with the active Fishman
powerchip does the magnetic + piezo the best but you have to get out
your wallet to go that way. The feature I like with that one is you can
have two amps and put the piezo into one and the magnetic into another.
Nice effect!

The one gutiar I've not done is my Tricone. We yakked before about how
to add pickups to it. But it's too expensive to start drilling! Brrrr!

[Tony Done]

If you can figure out that passive mag/piezo circuit, I would be very
interested to know. - It would be an easy option. I've heard such
circuits mentioned before, but I've never been able to figure it out.

Did ya see how I put the pickup in my tricone? - Replaced the foremost
parallelogram screen holes with a nice piece of nickel-plated brass,
looks just like a bought one. I prefer magnetics for slide, because they
pick up the high transients if the pickup is located in about the
hypothetical 24th fret position.

[Tony Done]

> If you're going to try the piezo-side pot that Benj suggested, then
> maybe do a quick test. Jumper a resistor across the piezo to see if
> you like the difference in sound. I believe that you will hear that,
> but maybe you'll prefer the tone of the loaded piezo.
>
> Then if you decide you want to go with the down-stream circuit, I'll
> do one o' them fancy ascii schematics for you.
>

What I have got jury-rigged so far, made up from bits I found in the
workshop, is an A50K volume pot, a B25K tone pot with a 1.0microF cap,
set up in a typical volume-tone circuit from the preamp output. Both the
volume and tone controls seem to be in the right range. - The
pickup/preamp sounds very bright through my harsh workshop amp, and the
big cap brings it down to something like a jazz guitar tone.

[RS]

On Sat, 26 Oct 2013 15:37:09 +1000, Tony Done <tony...@bigpond.com>
wrote:

>

>> If you're going to try the piezo-side pot that Benj suggested, then
>> maybe do a quick test. Jumper a resistor across the piezo to see if
>> you like the difference in sound. I believe that you will hear that,
>> but maybe you'll prefer the tone of the loaded piezo.
>>
>> Then if you decide you want to go with the down-stream circuit, I'll
>> do one o' them fancy ascii schematics for you.
>>
>
>What I have got jury-rigged so far, made up from bits I found in the
>workshop, is an A50K volume pot, a B25K tone pot with a 1.0microF cap,
>set up in a typical volume-tone circuit from the preamp output. Both the
>volume and tone controls seem to be in the right range. - The
>pickup/preamp sounds very bright through my harsh workshop amp, and the
>big cap brings it down to something like a jazz guitar tone.

Hi Tony,

Tone caps work against whatever impedance is 'upstream.' In this
case, it sounds like you're hooking the cap directly to the output pin
of your preamp. That's not the best way to do it. You don't know the
exact upstream impedance at that point, and you also don't want to put
a reactive load directly on a 'black box' circuit. Maybe OK, but it's
unpredictable.

The problem can be solved by simply inserting a resistor in between
the output pin and your added controls. Call it R.

You want R to be higher in value than your approximated output
impedance, but maybe 1/4 value of your volume and tone pots. I think
your output impedance may be around 5k, so try a 10k series resistor R
for a start. Yeah that's not 1/4 the value of your tone pot, but if
you don't have another 50k, it will have to do.

Now you can calculate a more predictable rolloff value with a very
simple formula. There are three unknowns in play: R, Capacitance C,
and the rolloff frequency F. If you have two of those you can find
the third.

What that means in this case: You know R = 10k. You choose a rolloff
frequency, maybe 1KHz. Then just plug those two values into this
formula to find the right value of capacitor:

C = 160,000 / (R * F)

In this case, that's 160,000 / (10,000 * 1000)

So your cap will be 0.016 microfarads for 1khz corner frequency.

If you want more rolloff, then of course you'd use a higher value cap,
but that should serve as a start. I like more mids, so I try not to
let high end rolloff extend down too far.

Also, using the series resistor, you should be able to get by with a
much smaller cap than 1uf. (BTW, you had a 1uf cap in stock? That's
not an electrolytic, is it? Try to use mylar caps for anything in the
signal path.)


-/////---+--------
R | |
| |
--- |
C --- |
| |
/ /
/ /<----------
/ /
| |
--- ---
- -

Most browsers have a view option for 'fixed font.' You need that to
line up the schematic above.

PS: The value 160,000 in the formula above is a 'magic number' that I
derived by translating the standard formula's farads to microfarads,
and then compensated angular frequency (radians) to normal frequency
that we usually deal with (Hz). 160k in the numerator makes things
dirt simple.







feeding

own a
You want the
The volume i

[RS]

On Sat, 26 Oct 2013 02:49:02 -0400, RS <R...@sorrynospam.com> wrote:

>
>C = 160,000 / (R * F)
>
>In this case, that's 160,000 / (10,000 * 1000)
>
>So your cap will be 0.016 microfarads for 1khz corner frequency.

PS: I'm sure you know that you don't need to worry about an exact
value for the cap. If you want to start with 0.022, for example, you'd
calculate the corner frequency kind of like the way you got the cap
value:

F = 160,000 / (R * C)

That's 727 Hz. Maybe a better corner if you want to roll off more
highs. Given your comments, I have a feeling that you'll prefer an
even lower corner freq (maybe 0.033 or higher cap value). I'd be
curious to hear what you end up with.

[Tony Done]

Thanks, I'll try it today. I have some trimpots, so I'll try varying the
resistance.

[Tony Done]

On 27/10/2013 4:54 AM, Tony Done wrote:
> On 26/10/2013 5:11 PM, RS wrote:
>> On Sat, 26 Oct 2013 02:49:02 -0400, RS <R...@sorrynospam.com> wrote:
>>
>>>
>>> C = 160,000 / (R * F)
>>>
>>> In this case, that's 160,000 / (10,000 * 1000)
>>>
>>> So your cap will be 0.016 microfarads for 1khz corner frequency.
>>
>> PS: I'm sure you know that you don't need to worry about an exact
>> value for the cap. If you want to start with 0.022, for example, you'd
>> calculate the corner frequency kind of like the way you got the cap
>> value:
>>
>> F = 160,000 / (R * C)
>>
>> That's 727 Hz. Maybe a better corner if you want to roll off more
>> highs. Given your comments, I have a feeling that you'll prefer an
>> even lower corner freq (maybe 0.033 or higher cap value). I'd be
>> curious to hear what you end up with.
>>
>
> Thanks, I'll try it today. I have some trimpots, so I'll try varying the
> resistance.
>

Progress to date. I used the B25K pot as R and found an A50K pot for the
tone control. I can see the useful effect of altering the roll-off
corner, but the effect is only comparable to an passive electric circuit
when I use a 0.5microF cap - 0.022microF had no discernible effect at all.

[RS]

On Sun, 27 Oct 2013 11:16:51 +1000, Tony Done <tony...@bigpond.com>
wrote:

That's very surprising, Tony! I think something is askew there.

I did say that I'm usually conservative with treble corner frequency
(not the amount of rolloff, just the freq at which it happens). I
like to maintain mids to get buckerish sounds from Strats, and I know
the contours well. Both the numbers that I gave you are for high
treble rolloff, not complete mid-scoop. But they should definitely be
audible.

Consider that Fender's bass circuit -does- scoop all mids and only
corners around 32hz. That's over an octave under the guitar's low E.
Turn off all treble and mid on a Fender amp and you'll see that.
Really bassy, right?

Now compare with your combo of 25k/0.5uf: That's a corner of 13Hz!
Way low. Even an octave lower than the Fender with nothing but bass.
I'd love to see exactly what's going on there.

Go with what works for you for now, but when you get time, could you
double check the series pot value to make sure the case marking is
correct?

[Tony Done]

Maybe the preamp is generating a huge amount of top end? Anyway, I did
check the R values of the pot in all sorts of combinations with the tone
pot, and the value you suggested around 5K was about right for removing
the brightness without killing the mids. In fact, with the 0.5microF
cap, R set at about 5 to 7k and the tone wound off about halfway in
effect, it sounded pretty much like a louder version of the guitar
itself. - Going from 1 to 10 on the volume pot sounded like the guitar
itself was getting louder. Altogether a satisfactory result. - I'm
seriously thinking of putting the R pot in as an extra control.

[RS]

On Sun, 27 Oct 2013 17:00:55 +1000, Tony Done <tony...@bigpond.com>
wrote:

I do that a lot. It's difficult to do in a passive guitar, cause you
need a relatively low impedance to drive it efficiently. But it works
very well when you have a buffer/preamp.

Basically the difference in the two types of controls, functionally:

1: Fixed freq, shelving (conventional): The corner frequency is
fixed. Below that the level remains pretty constant. Turning the pot
changes the height of the upper shelf. And it will look much like a
flat shelf moving up and down. This is why jazz guys often end up so
dark; in an attempt to roll off extreme highs, the amp controls also
roll off so much midrange that only bass prevails.

2: Variable frequency (like varying R above): The pot slides the
corner frequency up and down, and everything above that is rolled off.
If you want treble, you simply set that frequency very high, but when
you back down, it doesn't cut into mids. I find that it's the most
useful type of control for cutting hash after an overdrive, and for
jazz. Even for straight rock, if I had a choice of only one of the
two types, I'd pick variable frequency.

I recommended a V.F. circuit to "TheChris" a few months ago as a
solution to...maybe an overdrive or something? I don't think he tried
it, but if so, maybe he can advise on how it worked out for him.

[RS]

On Sun, 27 Oct 2013 17:00:55 +1000, Tony Done <tony...@bigpond.com>
wrote:

>In fact, with the 0.5microF
>cap, R set at about 5 to 7k and the tone wound off about halfway in
>effect, it sounded pretty much like a louder version of the guitar
>itself.

If you run those values thru the equations that I gave you, you'll see
that the corner is around 64 Hz. Still low, but now higher than the
Fender bass-side rolloff. (Which uses 100k / .047, BTW)

> Going from 1 to 10 on the volume pot sounded like the guitar
>itself was getting louder. Altogether a satisfactory result. - I'm
>seriously thinking of putting the R pot in as an extra control.

I had originally recommended the current pot values because there was
some concern expressed about rolloff due to cable capacitance. But
given that you are serious about rolling off highs, you shouldn't
worry about that.

This means that you can scale all the resistor and pot values up (and
the cap value down, of course), which will give you more range on the
variable F control (R). You could try a 250k control for volume and
around 100k for the R pot. A 0.047 would give you Fender-like
frequency for max rolloff, but of course you could use a 0.1, since
backing down R to 50k would get to you Fender turf. You probably want
to use a linear taper pot, or even reverse-log if you can find it.

Remember to use mylars if you do end up with a high value cap.

[Desk Rabbit]

On 25/10/2013 01:55, Tony Done wrote:
> On 24/10/2013 6:34 PM, Desk Rabbit wrote:
>> On 24/10/2013 03:21, Tony Done wrote:
>>> I have a simple Martin Matrix piezo preamp and couple of Schatten bug
>>> piezos that seem to work OK through it. How would I add passive tone and
>>> volume controls? On the input or on the output side? I measured the
>>> resistance, and it was off the scale (more than 20M) on the input, and
>>> about 100K on the output side. Any suggestions for pot and cap values?
>>>
>>> Thanks.
>>
>> You need one of these:
>> http://www.orchid-electronics.co.uk/acoustic.htm
>>
>> or these
>> http://www.fishman.com/products/filter/type:preamps
>
> I'm trying to put together an internal preamp from parts I have on hand.
> If I was going for an external preamp it would likely be a Red Eye.
>

They look a bit EQ limited for acoustic guitar. I love my Orchid
(Favoured by and designed for Show of Hands here in the UK) and in
particular the Mid control. Lift it for finger picking, drop it back for
strumming. With a mute switch (You don't then have to stand there like
an idiot trying to make the sound engineer notice that you need to
switch guitars) and a constantly live tuner out, it's perfect for live gigs.

[Tony Done]

The reason I would look at the Red Eye is because a couple of blokes who
earn their living playing acoustic guitar swear that it the best there
it. On the topic of mid range, the Maton AP preamp is nice, It has a
control that alters the midrange peak between 1K and 2K, and a another
that gives about 15dB cut or boost, in addition to the normal treble and
bass controls. This system really alters the character of the guitar's
sound, but I don't know how it would go with other pickups, because it
is designed for piezos with a fairly high output.

[Desk Rabbit]

Guess they haven't tried an Orchid yet ;-)

I'm not quite pro yet but I earn a fair chunk of my income from music
and one band I play in is a headline act at Folk clubs around the UK so
I'm well versed in the acoustic amplification arena. Some clubs have
awful PA and the Orchid fixes most of them but there's only so much you
can do!

> it. On the topic of mid range, the Maton AP preamp is nice, It has a
> control that alters the midrange peak between 1K and 2K, and a another
> that gives about 15dB cut or boost, in addition to the normal treble and
> bass controls. This system really alters the character of the guitar's
> sound, but I don't know how it would go with other pickups, because it
> is designed for piezos with a fairly high output.
>

A friend of mine loves Maton guitars, he's got about 5 I think at last
count. The most surprising one is a tiny little travel guitar with a
built in Maton preamp. When played acoustically it sounds like complete
shite but put it through a PA or AER amp and it sounds gorgeous!

[Tony Done]

>
> Guess they haven't tried an Orchid yet ;-)
>

Yeah, my info is fairly USA-centric

> I'm not quite pro yet but I earn a fair chunk of my income from music
> and one band I play in is a headline act at Folk clubs around the UK so
> I'm well versed in the acoustic amplification arena. Some clubs have
> awful PA and the Orchid fixes most of them but there's only so much you
> can do!
>

I'm an ex Brit mid-60s folkie (left the UK in '75), but only started
doing gigs in the early '90s, mostly acosutic blues.

>> it. On the topic of mid range, the Maton AP preamp is nice, It has a
>> control that alters the midrange peak between 1K and 2K, and a another
>> that gives about 15dB cut or boost, in addition to the normal treble and
>> bass controls. This system really alters the character of the guitar's
>> sound, but I don't know how it would go with other pickups, because it
>> is designed for piezos with a fairly high output.
>>
>
> A friend of mine loves Maton guitars, he's got about 5 I think at last
> count. The most surprising one is a tiny little travel guitar with a
> built in Maton preamp. When played acoustically it sounds like complete
> shite but put it through a PA or AER amp and it sounds gorgeous!

Matons have done an assortment of really good and bad stuff over the
years. The new Maton acoustics have been re-engineered in consultation
with Taylor, and are much more open sounding than the older versions of
the same basic models. I've currently got two (see my Flickr pics), and
the first good guitar I ever bought was a 1975 FG100. The Maton AP
preamps have a very good reputation, IIRC the were designed by West
Electronics or something like that. I once read that Tommy E has the
original brand-name preamps installed in his guitar, but I've no idea
whether that is true or not.

[Tony Done]

OK, after a lot of distractions I have got what seems to be a decent
tone control. - With the assistance of my tech mate Terry. Using your
diagram from an earlier post, R is a B10K, the cap is 0.047microF, the
toe control is A25K and the volume is A50K, connected at the junction of
R and the cap. It seems to work well with the piezo bug, and also with a
couple of magnetic pickups I tried. As Terry said, it could be mistaken
for a subtle midrange control. Not sure when I'll install it, but at
least I now have all the components on hand.

Anyway, thanks for your help.