Noise problem with Morley volume pedal
Ken Kaliszewski
I have a Morley volume pedal that has been incredibly noisy ever since I bought it. When I
brought it back to the Guitar Center (Santa Ana, CA), they didn't have a replacement and
some chum told me to use an electronic cleaner and "work with it" and the noise would go
away. I've tried ElectoWash and WD40 and "worked with it" as much as I could handle the
obnoxious scratching!! Has anyone else had this experience or does anyone have any
suggestions (short of throwing it away!)... Is it easy to change the pot? Is there a
special pot to use or can I use any volume pot? Maybe there's some other cleaner that
might work better...???
Any help is appreciated.
Ken
JONATHAN H EPSTEIN
>
>I have a Morley volume pedal that has been incredibly noisy
>obnoxious scratching!! Has anyone else had this experience or does anyone have any
>suggestions (short of throwing it away!)...
My friend has problems with his Crybaby Wah has sent two back to the to
Dunlop factory and they have since returned brand wahs to him at no
charge (even no shipping charge)
I was thinking of sending my Wah back to Morley, but have been too
lazy to get the address, and am also uncertain of the Morley warranty
>Any help is appreciated.
I'm going to try to send my pedal back (if someone can give me the
Morley address) I'll let you know if anything comes of it.
>Ken
-Jon
David Morning
>Any help is appreciated.
I thought the Morley used an optical system of control to try and avoid pot
crackling?
BTW Can you try and stick to 80 char. width? It's easier on the old eyes!!
Dave
--
R.G. Keen
pot problems. You probably have a leaky or shorted capacitor
which is supposed to be blocking the DC away from the pot, but
is letting some DC through. Replace the blocking capacitors
to/from the pot.
By the way, WD-40 is *-NOT-* a cleaner. Use a spray cleaner
designed for controls.
Chris Peckham
their Volume and Wah pedals. I think they use a Hall device whose
resistance or something changes with the proximity of a magnet
mounted on the rocker part of the pedal. This is intended to avoid
worn and noisy carbon(?) tracks on the more common pot.
Chris
Adam C. Coggins
This reminds me of something that has been bugging me--that volume
pedals with passive electronics (i.e. a potentiometer [variable
resistor] and maybe a smoothing capacitor) tend to cost $40+.
A potentiometer costs ~1.50 at Radio Shack, and input/output jacks and
simple resistors and capacitors cost even less, so why the high price?
Now, if the volume pedal had a built-in pre-amp or a hall-effect sensor
(like the Morley mentioned above), I could understand the cost. But
for just a potentiometer.
Anyhow, enough of my complaining--I'll make my own.
-Cody Coggins
<acog...@phoenix.princeton.edu>
Don Tillman
Organization: Princeton University
Date: Sun, 20 Sep 1992 23:24:39 GMT
In article <1992Sep18.1...@mnemosyne.cs.du.edu> cpec...@nyx.cs.du.edu (Chris Peckham) writes:
>I likewise, have heard that Morley don't use variable resistors for
>their Volume and Wah pedals. I think they use a Hall device whose
>resistance or something changes with the proximity of a magnet
>mounted on the rocker part of the pedal. This is intended to avoid
>worn and noisy carbon(?) tracks on the more common pot.
Morley's are optical. The Hall Effect is completely inappropriate
technology.
This reminds me of something that has been bugging me--that volume
pedals with passive electronics (i.e. a potentiometer [variable
resistor] and maybe a smoothing capacitor) tend to cost $40+.
A potentiometer costs ~1.50 at Radio Shack, and input/output jacks and
simple resistors and capacitors cost even less, so why the high price?
Now, if the volume pedal had a built-in pre-amp or a hall-effect sensor
(like the Morley mentioned above), I could understand the cost. But
for just a potentiometer.
For most stomp pedals, the active electronics is the least expensive part
of the product.
The most expensive part is the chasis (casting, stamping, painting,
silkscreening, assembling, etc) followed by (in no particular order)
switches, pots, connectors, labor, and testing. Higher quality pots,
connectors and switches obviously will cost more, and if the box is going
to be stomped on, money spent there will pay off. Way down at the bottom
are the electronics parts like transistors, op-amps, resistors, etc. The
electronics for something like a Fuzz Face probably costs around 75 cents,
including the pc board.
The exceptions are some of the more electrically complicated boxes like
flangers, and echos.
So for a volume pedal, I think it's completely reasonable to spend the
bucks and get something reliable.
-- Don
Michael Breen
>This reminds me of something that has been bugging me--that volume
>pedals with passive electronics (i.e. a potentiometer [variable
>resistor] and maybe a smoothing capacitor) tend to cost $40+.
>
>A potentiometer costs ~1.50 at Radio Shack, and input/output jacks and
>simple resistors and capacitors cost even less, so why the high price?
>Now, if the volume pedal had a built-in pre-amp or a hall-effect sensor
>(like the Morley mentioned above), I could understand the cost. But
>for just a potentiometer.
>
>Anyhow, enough of my complaining--I'll make my own.
>
>-Cody Coggins
><acog...@phoenix.princeton.edu>
>
I hope Morley does not use Radio Shack parts. A good potentiometer will
cost you more than $1.50...certainly not >$40 though.
What you are really paying for is the pedal itself. If you started out
with an empty Morley pedal, and did all the electronics yourself, you
could get it done with top-quality parts for about $10. But to start
out with a chunk of metal in a machine shop, and get to the same point
would cost you >$40 in hassle and cut/burned fingers.
It would probably end up costing you much greater than the cost of a
pedal in lost time/hassle/actual parts.
This is *not* true of all man-made things, but in most cases it is
easier and much cheaper to build 1000 of something than it is to make
one. Then a company can add a hefty profit and *still* bring it to
the customer for less than s/he can make it for from scratch.
Some people (myself included) have access to machine tools, and consider
it great fun to make things. Cody may be in that group. In that case,
it is worthwhile to make a single 'custom' tool for yourself, cause even
if it costs more in actual $, some of that is recouped in pleasure-of-
creation.
Michael Breen
singing and philosophizing
Peter Quince
>This is *not* true of all man-made things, but in most cases it is
>easier and much cheaper to build 1000 of something than it is to make
>one.
That is, effort per unit, of course. I agree.
Along these lines (and I will reiterate this in a separate article),
I have finished putting together the onboard preamp spec'd out in _The
Guitar Handbook_. A prelim wire up indicated that it does indeed work.
In a couple few days I will do the jury rig hook up and fuss with the
adjustment pot. The big questions then will be:
o what will the gain be? (which i asked myself as i started)
o is it noisy?
o what kind of a whammy does it put on the signal?
If I resolve these things to my satisfaction in the affirmative, i.e.
o good, with good results all the way through the amp
o silent
o none
then it will be time for the real installation. The design is very
compact; it uses veroboard and a few components and an op-amp. As
such it should fit pretty tightly in the pickup selector switch cavity
under the finger plate of my friend's shitty strat. (Should I tell
my friend? Will he still be my friend? More questions...)
And so all this is just sort of an info-mational post; I will speak
up again after the above is all done, at which point I will start
(probably redundantly) asking around about schematics for
other signal-altering circuits. Thanks for listening... its been
a pleasure.
pquince
--
If you can't kill me, stop wasting my time!
META000
>.
I've had a preamp in my axe for over a decade, and have installed
them in other guitars. I recommend NOT setting the gain above 4 or
5, for the following reasons. Most on-board preamps employ 9v
batteries as their power source, using a floating ground that
provides +/- 4.5 V. Many modern pickups can provide an output
easily in the 1-volt range, on their own, if you give them a good
wallop. Since the little pre-amp cannot supply greater output than
its' power supply, a little arithmetic (5 x 1) indicates that it is
extremely easy to use up a big chunk of the pre-amp's headroom with
a gain of 5, and very easy to go into clipping with gains of more
than that. If on-boardpre-amps were designed as purposefully
distorting devices, that would be one thing, but these things
generally soud lousy when they go into clipping.I might point out,
as well, that if you are intent on overdriving somesubsequent stage,
it becomes very hard to get subtle distortion sounds when the guitar
output is too high.
Just a thought. Mark Hammer
Don Tillman
From: pqu...@blacks.jpl.nasa.gov (Peter Quince)
Organization: Image Analysis Systems Group, JPL
Along these lines (and I will reiterate this in a separate article),
I have finished putting together the onboard preamp spec'd out in _The
Guitar Handbook_. A prelim wire up indicated that it does indeed work.
In a couple few days I will do the jury rig hook up and fuss with the
adjustment pot. The big questions then will be:
o what will the gain be? (which i asked myself as i started)
0.8 dB gain with the adjustment pot at minimum, 20.8 dB with the adjustment
pot at maximum.
o is it noisy?
Depends upon the opamp you use. For a TL071, somewhat noisy. For a 741,
extremely noisy.
o what kind of a whammy does it put on the signal?
It'll sound okay to lame depending upon the opamp used.
I personally don't like the sound of opamp-based preamp circuits. The
noises and distortions they produce are annoying and umusical and when
overdriven their clipping sounds very buzzy and recovery is ungraceful.
For me a discrete FET circuit is the best way to go and, as a side effect,
is only half the space (4 resistors, 1 fet, 1 cap, less wiring, add a cap
and a pot if you need the gain adjustment).
-- Don
Mark Andrew Hawling
>noises and distortions they produce are annoying and umusical and when
>overdriven their clipping sounds very buzzy and recovery is ungraceful.
>For me a discrete FET circuit is the best way to go and, as a side effect,
>is only half the space (4 resistors, 1 fet, 1 cap, less wiring, add a cap
>and a pot if you need the gain adjustment).
>
> -- Don
>
Can you post one of your FET designs that you think is good.
Thanks
Mark
Richard Stern
>
> I personally don't like the sound of opamp-based preamp circuits. The
> noises and distortions they produce are annoying and umusical and when
> overdriven their clipping sounds very buzzy and recovery is ungraceful.
> For me a discrete FET circuit is the best way to go and, as a side effect,
> is only half the space (4 resistors, 1 fet, 1 cap, less wiring, add a cap
> and a pot if you need the gain adjustment).
Try this op-amp based pre-amp using the following circuit.
This is a design from Mike McTigue who has posted this a few times already.
Mike has this pre-amp in both of his electrics, I have it in 2 of my
electrics, and we've built them for friends who are very happy with them.
This circuit has no noticable noise or distortion, and a 9 volt battery
seems to last forever (none of us have had to replace one yet in 2+ years).
Please note that the purpose of this pre-amp is to act as a buffer between
the R of the volume pot and the C of the cable. I did modify one of mine
for gain, but I use it set to a gain of 1 almost all the time.
1M ohm 1M ohm
+9v---\/\/\/--------O-----\/\/\/---gnd
|
from |
pickup /
switch 500k \
| ohm / +9v
| \ |\ |
250k \ | 3 | \ |
vol / <------||----O-----|+ \|7
pot \ .1 uF | \
/ | u1 \_____o------\/\/\/----||----->
| 2 | / 6 | 50 1uF to
| o------|- / | ohms cable
gnd | | /|4 |
| |/ | |
| gnd |
| |
o-----------------o
u1 LT 1012 uPower op amp or other low noise low power op amp
(use a stereo jack to turn on/off the power)
Richard Stern
rst...@col.hp.com
META000
>.
Although this circuit will not provide any gain itself, by buffering
the output against potential signal loss due to cable capacitance,
you end up with a brighter sound that tends to "cut through" better
(assuming that's what you want). In effect, although the guitar
"sounds" boosted, all that's happened is you hung on to the whole
signal, and not just what was left at the end of the cable. Given
how powerful many contemporary pickups are, this is probably all you
want anyways, in terms of signal enhancement at the guitar. It gets
my vote.
Mark Hammer
Don Tillman
From: rst...@col.hp.com (Richard Stern)
Organization: HP Colorado Springs Division
Try this op-amp based pre-amp using the following circuit.
(Umm, proper engineering practice requires you to decouple the 9v supply
and to bypass the lower 1Mohm resistor with a .1 uF (or so) cap,
especially if you're driving a load.)
The design you present is nearly identical to the "Guitar Handbook"
circuit that started this conversation, and suffers from the same
problems -- high feedback, bad feedback topology, ungraceful overload
and recovery, noise, and the signal has to go through a dozen non-linear
devices inside the chip before it gets out. Exactly the sort of thing
that gives solid-state amps a bad reputation!
Date: Mon, 28 Sep 1992 13:15:11 -0500
From: Kurt Taylor <ku...@istwok.ods.com>
Please post a schematic of your fet pre-amp. (I have tried many op-amp based
circuits with little success, unless you like BAD pre-amps :'))
Date: Tue, 29 Sep 92 10:34:54 -0400
From: t...@godzilla.eecs.umich.edu (tim stanley)
You mention your preference for FET based pre-amps. Can you give me
any pointers to where I can lift a schematic of such a critter?
Date: Tue, 29 Sep 1992 07:55:32 GMT
From: ch...@spectrum.cs.unsw.oz.au (Mark Andrew Hawling)
Can you post one of your FET designs that you think is good.
Well okay. Here's a nice design from the "op-amps are for weenies"
school. Low distortion, low noise, low feedback, graceful overload,
simple, elegant, inexpensive, etc. This baby sings. It has a transfer
characteristic somewhat similiar to the first 12AX7 tube in a Fender
amp.
+------------------------+--- +9v
| |
< |
< 6.8k |
< |
| 5uF |
+----||----+--- out |
| | |
|-+ | |
in ---+----->| | |
| |-+ | |
| | | |
< 10M < 2.2k < 51k ---
< < < --- 10uF
< < < |
| | | |
+--------+----------+-------------+--- gnd
The FET is a 2N5457. The voltage gain is subtle, 3dB or so. You can
substitute another low-Vdss FET if you know what you're doing. Power
drain is about 0.5 mA, so a 9v batter will last a good long time. It
does start to sound a little grubby when the battery sinks below 7v.
It's also trivial to add a high-boost switch if you'd like; have it
shunt the 2.2k resistor with a 0.05 uF (adjust to taste) cap. Or shunt
the 2.2k resistor with a 10uF cap for more gain.
Obviously you want to wire it so it's powered off when the instrument
isn't plugged in -- it's far superior to use a switched jack instead of
the weenie approach of using the second connection of a stereo jack.
Also note that this design is easily phantom-powered, so you can even
get by without installing a battery.
-- Don
Mike McTigue
I'm the one who "designed" the LT1012 opamp circuit for a guitar
preamp. I refuse to get into a disscussion (flame war) on this
subject. Below I will state the reasons why I believe it is pefectly
fine for THIS application.
o High feedback is exactly what I want. I do not want this preamp
to color the signal AT ALL. I have a tube amp to do that and it
does that job very well. High feedback means it reproduces the input
*exactly*. If I want something to color the sound, it goes in my
effects.
o Yes you probably should bypass the 9v battery. Use a 10uf tantalum or
so.
o Overdrive recovery is not an issue for this preamp. The signal is
small and will never drive the output of the opamp anywhere near
the rails.
o What gives transistor amps a bad reputation is that they a) do not
color the sound the way people have come to like and b) they do
not saturate the same way as amps people have come to like.
In summary, if you want a preamp that colors your sound then definately
look into various fet preamps. The extent to which they color your sound
will depend on how linear they are and what their transient response
looks like. If however, you are already very happy with your sound but
would like a preamp that simply buffers your signal so it can drive a
capacitive cable without attenuating the high end, use a high feedback
opamp circuit with enough slew rate.
Mike M
Don Tillman
Date: Mon, 5 Oct 1992 17:02:21 GMT
Organization: HP Colorado Springs Division
o High feedback is exactly what I want. I do not want this preamp
to color the signal AT ALL. I have a tube amp to do that and it
does that job very well. High feedback means it reproduces the input
*exactly*. If I want something to color the sound, it goes in my
effects.
Aha, I see the problem! I absolutely agree with you that it's not the
preamp's job to color the sound. But unfortunately *everything* colors the
sound. Heck, even doing nothing colors the sound (which is why we're
building preamps in the first place, so we don't lose the signal to the
cable). The issue is which approach affects the sound in the least
objectionable manner.
The FET circuit I presented is a single mostly linear device. The few
distortions it does have are considered very musical, and a small amount of
local feedback (12dB or so) is applied to linearize that down to
virtual inaudibility.
The op-amp approach is a set of a dozen non-linear devices on a chip, with
non-musical distortions, and a ton of feedback to correct for that. The
comprimise feedback topology is such that not all of the distortions can be
corrected for. The op-amp itself is optimized for high gain instead of low
distortion, but the stability requirements are such that the gain available
for feedback correction is much less at high frequencies. Not all the
distortion gets corrected, and new distortions are created in the process.
The most glaring examples of this problem are the cheezy specsmanship-
pissing-contest hifi amps of the late seventies (Technics, Pioneer, etc) --
amps with large amounts of feedback, low distortion specs, and lousy sound.
It should be clear why I prefer the FET appoach.
If you want technical references, I can dig them up, though I'd rather
spend the time playing guitar. Then again, playing's too important for me,
just check out late 70's issues of the Journal of the Audio Engineering
Society and look for articles by Matti Otala, Peter Garde, and Marshall
Leach.
So these are gonna sound different. I find the op-amp sound irritating,
although others may not mind, and still others may actually prefer it. The
musician decides which they prefer and makes the most of it.
-- Don
Richard Stern
[more discussion of FET vs op-amp preamps]
> So these are gonna sound different. I find the op-amp sound irritating,
> although others may not mind, and still others may actually prefer it. The
> musician decides which they prefer and makes the most of it.
I'd find it very hard to believe that you can really tell the difference.
Maybe you can, but I know that I cannot. I have Mike's op-amp design
in my guitars, and one of them has a switch to bypass the pre-amp. With
the guitar volume control on 10, I cannot hear any difference between
bypass or not. When I roll the volume control down, the pre-amp preserves
the high-end, and in bypass there is a noticable roll-off of highs.
Your signal is coming from a guitar pickup with limited bandwidth, going into
a guitar amplifier that is far from accurate and has limited bandwidth, and
then going into a guitar speaker that adds it's own distortion. Now tell me
that putting an op-amp follower (buffer! No gain) in the signal path changes
the signal enough for it to be irritating. Very hard for me to believe.
We're not talking about digital (or high end analog) audio and hi-fidelity
amps and accurate speakers etc. In these cases, I'm sure the op-amp
limitations show up very clearly. But this is not rec.audio.high-end.
This is wreck.plug.it.in.and.crank.it.up :-)!
Richard Stern
rst...@col.hp.com
FWIW, I'll probably build one of your FET designs just to see if I can
hear a difference. Maybe I'll surprise myself.
David Bell
>
[Schematic and text deleted]
>
>Also note that this design is easily phantom-powered, so you can even
>get by without installing a battery.
>
> -- Don
Excuse my ignorance, but what exactly does this meen ?
--
Dave Bell
Sea Change Corporation
Mississauga, Ontario, Canada
...!uunet!uunet.ca!seachg!db
Don Tillman
From: rst...@col.hp.com (Richard Stern)
Organization: HP Colorado Springs Division
ti...@acid-rain.lucid.com (Don Tillman) writes:
> So these are gonna sound different. I find the op-amp sound irritating,
> although others may not mind, and still others may actually prefer it. The
> musician decides which they prefer and makes the most of it.
I'd find it very hard to believe that you can really tell the difference.
Maybe you can, but I know that I cannot.
Perhaps you can't. Since you haven't tried the FET preamp, it's really
hard to say isn't it? No matter. Please note however that throughout this
discussion I've been careful to never tell anybody what they can hear, what
they ought to prefer, or what they should sound like; I've only corrected
technical errors. (Specifically claims like, "High feedback means it
reproduces the input *exactly*.")
Your signal is coming from a guitar pickup with limited bandwidth, going into
a guitar amplifier that is far from accurate and has limited bandwidth, and
then going into a guitar speaker that adds it's own distortion. Now tell me
that putting an op-amp follower (buffer! No gain) in the signal path changes
the signal enough for it to be irritating. Very hard for me to believe.
Heh-heh-heh, you assume that I just plug it in and crank it. Depending
upon the circumstances I play direct to tape and headphones (in stereo),
direct to stereo PA, direct to high-fidelity equipment, or into a heavily
modified Fender Twin outfitted with piezoelectric tweeters. When I finish
building my new speaker cabinets I'll have a very high fidelity biamped
system.
So yeah, I'm kinda serious about having a clean sound.
-- Don
Don Tillman
Date: 5 Oct 92 12:38:06 GMT
Organization: Sea Change Corporation, Mississauga, Ontario, Canada
In article <TILL.92Se...@acid-rain.lucid.com> ti...@lucid.com writes:
>
>Also note that this design is easily phantom-powered, so you can even
>get by without installing a battery.
>
Excuse my ignorance, but what exactly does this meen ?
"Phantom power", from the latin "phantasma potere" (powerful, but from no
apparent source), means that the output signal of a preamp and the supply
voltage to power it both run on the same wire.
This is possible without compromise due to a fluke in the circuit: you can
cut the circuit at drain of the FET, place the left half in the instrument,
place the right half in a powered box a cable away, and it'll work just
fine with just a hot lead and a ground lead.
This technique is used alot with condenser microphones, and many
professional mixing consoles offer phantom powered mic inputs -- inputs
with a resistor pull to a supply voltage. Those Radio Shaft PZM mics are
phantom powered f'rinstance.
-- Don
clifton....@gmail.com
IOW, I'm playing without the pedal engaged, click it on to use it and then when I click it to turn off it will not return to the previous setting, in fact I get nothing, silence, like there's a short or something.
Can anyone help me with this?
Pudentame
wrote:
diagram you can download.
You're going to need a multi-meter to do continuity checks throughout;
a soldering iron to replace the faulty capacitor & a new SPDT
footswitch to replace the faulty switch.
Twang
it's opto electric.
I had one and reset that little band of rubber that when you move the pedal either blocks or
unblocks the rubber thingy from the light inside.
I haven't had it open for ages. So it's hard to remember all that's in there. mine's old.. just a pedal and an off/on switch outside.
you can spray all the shit in there you want and it wont help.
Oh.. one thing it had a 250K Resistor which I swapped to a 1MegOhms Resistor and it was 100% better..
I haven't read all these replies.. I'll check 'em out now. and if I don't see a solution offered I'll crack mine back open and run you through the fix!
TWANG
ps I build amps so.. I know wtf and wont steer ya wrong.