Sola Sound - Tone Bender Mark I (1965)

graemey · Post by **graemey** » 12 Jul 2009, 17:52

Quick up-date for anybody who's interested...

I just couldn't get rid of the high pitched noise from this circuit so I invested in a component analyzer to check my trannys for gain and leakage.
I selected three goodies (OC75 and two AC125's) and guess what? it still made the screaming sound on any setting above minimum on the fuzz control.

Next I decided to remove the 8k2 resistor on the base of Q3 and replace it with a 10 trimmer. As soon as I backed the 10k down to almost zero, the shrill noise disappeared.
Now, at last, this thing works like a fuzz box. I think anyone building a mk1 without a pair of 2G381's should consider a 10 trim pot at this point of the circuit.

I really like this pedal and find it sounds punchy and open with single coils but can be a little muddy on the bass notes with humbuckers. Backing down the guitar volume seems to cure this.

sonicvi · Post by **sonicvi** » 12 Jul 2009, 19:53

I came up with a little mod while working on my last build that killed that noise but without changing the tone significantly. Try putting a .1uF or so cap from Q2's collector to ground and see if it helps at all. You don't have to sacrifice any gain/sustain this way as well.

graemey · Post by **graemey** » 12 Jul 2009, 20:16

sonicvi wrote:I came up with a little mod while working on my last build that killed that noise but without changing the tone significantly. Try putting a .1uF or so cap from Q2's collector to ground and see if it helps at all. You don't have to sacrifice any gain/sustain this way as well.

Good call, I'll try that!

RnFR · Post by **RnFR** » 12 Jul 2009, 23:25

sonicvi wrote:I came up with a little mod while working on my last build that killed that noise but without changing the tone significantly. Try putting a .1uF or so cap from Q2's collector to ground and see if it helps at all. You don't have to sacrifice any gain/sustain this way as well.

doesn't that roll off a lot of high end?

sonicvi · Post by **sonicvi** » 13 Jul 2009, 14:44

RnFR wrote:
sonicvi wrote:I came up with a little mod while working on my last build that killed that noise but without changing the tone significantly. Try putting a .1uF or so cap from Q2's collector to ground and see if it helps at all. You don't have to sacrifice any gain/sustain this way as well.
doesn't that roll off a lot of high end?

yes, that was the idea. The MK1 doesn't have a lot of treble to begin with, so it bleeds off all the annoying high-end noise but doesn't significantly affect the tone. You may need to choose another value to suit your build .1uF worked for mine.

Solidhex · Post by **Solidhex** » 01 Aug 2009, 04:52

Yeah

The high end sizzle and sometime oscillation is really common problem in this circuit! Its a real balancing act to get the amount of clipping right in the last two stages. It helps to listen to the output of each stage and see what's happening. Things can get out of control pretty easily. Swapping the 2m2 in and out will give a good example of how it tames the circuit a bit. What sounds like a totally useless mess of oscillation can shape up pretty good once it hits the 2m2. It can also make it sound lifeless too.

--Brad

graemey · Post by **graemey** » 26 Sep 2009, 10:26

If you haven't seen it already...

My Tone Bender M1 build video

RnFR · Post by **RnFR** » 26 Sep 2009, 19:21

graemey wrote:If you haven't seen it already...

My Tone Bender M1 build video

nice!

Kregg · Post by **Kregg** » 27 Sep 2009, 22:14

I like the tone of the Mark 1.5. What change in the components makes it different from the Mark 1?

sonicvi · Post by **sonicvi** » 28 Sep 2009, 03:09

Kregg wrote:I like the tone of the Mark 1.5. What change in the components makes it different from the Mark 1?

All of them. They're completely different circuits.

Electric Warrior · Post by **Electric Warrior** » 28 Sep 2009, 07:58

here's a layout..

Kregg · Post by **Kregg** » 28 Sep 2009, 13:26

Thanks guys. Google was only showing me MK I or II due to their popularity.
Sometimes google is like having a name ending in W,X,Y,Z ... it makes traffic court a long day.

The Rotagilla · Post by **The Rotagilla** » 11 Oct 2009, 19:14

Sorry if I missed it but does anyone know the correct tapers from the volume and attack pots? Thanks.

SPeter · Post by **SPeter** » 12 Oct 2009, 10:26

Attack - Linear or RevLog( I didn't try the second one)!
Volume Log or Linear( I do often prefer Linears)!
Cheers,

Kilby · Post by **Kilby** » 09 Nov 2009, 14:10

Sorry as I may be being a bit thick.

Is there any chance of getting the V1 diagrams being reposted (assuming that the Gary Hurst layout is not the same as the original Mk1)

Given the the eternal popularity of the Tone Bender would it be a good idea to have a verified circuit / layout topic for all the major versions of this pedal (Vers 1, 1.5, 2 & 3 ?)

I'm happy to contribute some PCB plans if nessicary.

If I have mussed such a thread already then Sorry!!!

Rob...

RnFR · Post by **RnFR** » 09 Nov 2009, 14:34

i did the gary hurst version because it has more components that can easily be left out of the circuit, and with a few value changes an original mk1 can be made. if you compare the two schematics you'll see what i mean. i'd post up a rework, but my original files are on my crashed hard drive that i still need to get fixed.

Kilby · Post by **Kilby** » 09 Nov 2009, 14:46

RnFR wrote:i did the gary hurst version because it has more components that can easily be left out of the circuit, and with a few value changes an original mk1 can be made. if you compare the two schematics you'll see what i mean. i'd post up a rework, but my original files are on my crashed hard drive that i still need to get fixed.

Well I was looking for the V1 but all the links (@ the start of this thread) seem to be dead, the Gary Hurst variation is probably close enough for my poor playing but I would like to have one of each (major) variation as it's the fuzz that I have always liked.

Other sites seem to have variable layouts.

RnFR · Post by **RnFR** » 09 Nov 2009, 14:50

just remove R4 and R11 and substitute proper values and you are there.

Kilby · Post by **Kilby** » 09 Nov 2009, 15:33

'60Burst · Post by **'60Burst** » 17 Nov 2009, 20:45

well I've built 2 of these with the same results. First thing I noticed with mine is the attack pot seems to be useless. At the lowest setting very little happens, just a very gated tone, I have to hit the strings very hard to get any sound. Then I move the knob a little and suddenly all the gain comes in which sounds okay, just gated sounding because I can't get it biased right. I used a 50k linear taper pot and then tried an audio taper pot but got the same thing. Why is there so little sound with the attack all the way down?

Also any suggestions on how to get this thing biased? I tried messing with the 2.2k resistor on Q2, 15k resistor on Q3 and the 8.2k off of Q3's base and I just can't get anything reasonable from it, just a gated crappy fuzz tone, nothing like some of youtube videos I've seen. Any suggestions on gain/leakage values?

Thanks!

Sola Sound - Tone Bender Mark I (1965) [schematic]