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

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...

Re: Sola Sound - Tone Bender Mark I (1965)

Postby sickman82 » 27 May 2014, 08:24

With regard to transistors, I got mine biased well with no squealing at all by using two very leaky transistors in Q1 & Q3, but with a transistor that had extremely low leakage in Q2. The Hfe of the transistors seemed to be less important than the leakage.

The cap from input to ground forms a low pass filter, similar (although a much larger value) to what you would use on the input of a Fuzz Face to reduce RFI.
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 27 May 2014, 08:39

jalmonsalmon wrote:
DrNomis wrote:
sickman82 wrote:Interesting, it's been a while since I looked at those schematics. It seems that it's the 56k that was dropped and the 47k moved. I had noticed that 470k change, I had that in there for a while, but changed to 180k and for me it seemed to work better.

I also noticed a few pages back that Dave had a 3n or 4n cap to ground on the input too.. low pass filter? I don't quite get it.. too big a cap to be a noise filter surely?

I swear this pedal could take over your life if you allow it.




He probably put that 3 or 4nF cap there to tame high-frequency screeching..... :hmmm:



Question about that cap to ground on the input... how is it that it kills the screeching?
I feel kind of dumb here LOL
Would think I could just use the stock schematic without that issue, or maybe I just have crap transisters LOL




The cap to ground probably forms part of a low-pass filter on the input I guess...... :hmmm:
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby jalmonsalmon » 28 May 2014, 21:49

I think I am getting close with this one finally... Using this layout http://www.freestompboxes.org/viewtopic.php?f=7&t=12720
I socketed a 1nf cap on the input to ground and I am still tweaking with different transistors. The bias should be 8k2 - 10k on Q2c , but so far I notice about a 4k resistor there is sounding good to me. I have been yanking out that 1nf cap on the input and it has a slight screech to it but not too bad, so I will not give up and keep tweeking... I love that layout and this pedal is almost where it should be... soon as I get it where it needs to be I will post my data and a sound demo...

THANKS :thumbsup
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby Masuto » 14 Jul 2014, 18:04

:applause: this must be the only forum where very long threads make for a very good read! :applause:
I keep coming back for more/reading this from the top again! :block:
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 28 Jul 2014, 18:16

Just been doing some experimenting with some AC125 Ge PNP transistors I recently bought off eBay, pretty much all of them turned out to have leakages ranging from about 620uA to just over 1 mA, anyway, I wanted to see how they would perform in the Mk I circuit so I selected three of them, turns out they sounded better/more gainier than the three AC128 transistors I was going to use, I think I have well and truly nailed it in my build this time, I'm going to make a couple of mods to the first transistor stage in my build, firstly I noticed that the biasing point of the first stage kept dropping with a 1M base biasing resistor so I tried changing it to 2M2 to see if that would help stabilize things, it actually made the bias point slowly increase, then I decided to try adding a 1M from the base of Q1 to the -V supply and I noticed that the bias point stabilized at about -5V, I also noticed that the gain-sweep from minimum to maximum was alot smoother too, the second mod I'm doing is to add a 10nF cap from the input to ground to stop the screeching, incidentally, while I was using my Oscilloscope to track down the cause of the screeching I noticed that reversing the orientation of the 22uF coupling cap between Q1 and Q2 seemed to get rid of the screeching, but, it made the fuzz control work backwards, so I put the 22uF cap back in the correct way, going to be working on putting the tagboard in it's box this week, will see if I can post a pic and a link to a soundclip so you can hear what my build sounds like.......stay tuned..... :thumbsup
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby jalmonsalmon » 29 Jul 2014, 00:23

DrNomis wrote:Just been doing some experimenting with some AC125 Ge PNP transistors I recently bought off eBay, pretty much all of them turned out to have leakages ranging from about 620uA to just over 1 mA, anyway, I wanted to see how they would perform in the Mk I circuit so I selected three of them, turns out they sounded better/more gainier than the three AC128 transistors I was going to use, I think I have well and truly nailed it in my build this time, I'm going to make a couple of mods to the first transistor stage in my build, firstly I noticed that the biasing point of the first stage kept dropping with a 1M base biasing resistor so I tried changing it to 2M2 to see if that would help stabilize things, it actually made the bias point slowly increase, then I decided to try adding a 1M from the base of Q1 to the -V supply and I noticed that the bias point stabilized at about -5V, I also noticed that the gain-sweep from minimum to maximum was alot smoother too, the second mod I'm doing is to add a 10nF cap from the input to ground to stop the screeching, incidentally, while I was using my Oscilloscope to track down the cause of the screeching I noticed that reversing the orientation of the 22uF coupling cap between Q1 and Q2 seemed to get rid of the screeching, but, it made the fuzz control work backwards, so I put the 22uF cap back in the correct way, going to be working on putting the tagboard in it's box this week, will see if I can post a pic and a link to a soundclip so you can hear what my build sounds like.......stay tuned..... :thumbsup


:popcorn:
You got my attention!
I have a variation of this circuit that seems to work well but always open for any updates. Mk1 is by far my favorite out of control sounding fuzz bar none! hehee :applause:
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 31 Jul 2014, 00:16

I just finished putting my Mk I build in it's enclosure and it's working good, will post a pic of the insides and a link to a soundclip soon..... :thumbsup
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 02 Aug 2014, 15:47

Ok, here's a pic of the insides of my Mk I build..... 8)
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby jreeves47 » 03 Aug 2014, 01:54

looks good!
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 03 Aug 2014, 14:48

Just thought I'd post a schematic for my Mk I build showing the mods I made to the original Mk I circuit plus some specs for the three transistors I used.... :thumbsup
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 03 Aug 2014, 16:32

Okay, at long last here's a link to a quick and dirty audio demo of my Tonebender Mk I build I uploaded on soundcloud, I have not applied any plugin effects to the recording, so that what you hear is what it sounds like, let me know what you think...... :thumbsup


https://soundcloud.com/drnomis_44/mk-i-tonebender-demo
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby jalmonsalmon » 04 Aug 2014, 00:10

DrNomis wrote:Okay, at long last here's a link to a quick and dirty audio demo of my Tonebender Mk I build I uploaded on soundcloud, I have not applied any plugin effects to the recording, so that what you hear is what it sounds like, let me know what you think...... :thumbsup


https://soundcloud.com/drnomis_44/mk-i-tonebender-demo


Nice! Thanks for the demo, sounds great, I will have to check out that schematic and do some breadboarding since I have a ton of AC125s to check out :thumbsup

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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 04 Aug 2014, 06:09

jalmonsalmon wrote:
DrNomis wrote:Okay, at long last here's a link to a quick and dirty audio demo of my Tonebender Mk I build I uploaded on soundcloud, I have not applied any plugin effects to the recording, so that what you hear is what it sounds like, let me know what you think...... :thumbsup


https://soundcloud.com/drnomis_44/mk-i-tonebender-demo


Nice! Thanks for the demo, sounds great, I will have to check out that schematic and do some breadboarding since I have a ton of AC125s to check out :thumbsup




Cheers for that, I compared the sound of my Mk I with some demo clips on youtube and to my ears my Mk I sounds very close, maybe a bit smoother perhaps, I also uploaded a soundclip of my Mk II with low Hfe OC81D transistors, you can find the link in the workbench section..... :thumbsup
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 21 Aug 2014, 01:05

Here's a little tip: use a 50k log pot for the Attack control if you want a more-gradual change in gain as you turn up the Attack control, if you use a 50k linear pot you'll find that there's a sudden change in gain at about the 9 oçlock position...... :thumbsup
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby Masuto » 26 Sep 2014, 17:11

Sup kids? Here we go go go again.
Bought 2 sets from Smallbear, one w/ oc75's and the other generic germs.
Built two stripboards for the generic set, worked at first then started making a bit of whizzing and noise, static or whatever as if the pedal wasnt properly grounded (it was).
I decided to go with 5% tolerance spanking new stuff and new xicon carbon comps-and i rebuilt it point to point.
SAME STORY- static noise when the guitar is not playing and a bit of pops and cracks even when its played!
But then i checked a video on youtoobe called 'tonebender mki 1965' and at the very end of the video the cat leaves the pedal on by itself:check it out...static, hissin, etc. So i guess my builds were proper!
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby Masuto » 26 Sep 2014, 17:19

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Re: Sola Sound - Tone Bender Mark I (1965)

Postby sinner » 26 Sep 2014, 18:39

DrNomis wrote:Ok, here's a pic of the insides of my Mk I build..... 8)


Nice. Is that my layout, Simon?

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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 26 Sep 2014, 19:21

sinner wrote:
DrNomis wrote:Ok, here's a pic of the insides of my Mk I build..... 8)


Nice. Is that my layout, Simon?



Yep, that's your layout and I can confirm that it works perfectly, so it's verified..... :thumbsup
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby DrNomis » 12 Feb 2016, 12:55

ljn wrote:Just tried. It doesn't show a "create account" button. It just loads up and freezes. Oh and it says in big letters, " We can't find this user". Thanks for trying, though.




Try this link, you should get the "Create Account" button this time:


https://soundcloud.com/
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Re: Sola Sound - Tone Bender Mark I (1965)

Postby absolutelyfibulous » 17 Dec 2017, 09:38

so i ended up buying a repro clone of this after so many times getting mine to sound brilliant up until the farting out note decay.

the clone sounds great but it's not board friendly at all so i figured that i would see why the clone works so well and then clone the clone.

they use essentially sinner's layout with remakes of the original transistors, a 10n from circuit in to ground, a 56k instead of a 47k at the end....and the secret sauce is a 680k from q3's base to the power.

i put a 2M pot on my battered mkI test board and the little sucker works! and as far as i can tell there isn't a difference in the tone. be careful turning that pot, though, because turning it all the way down caused some sparks and smoke.

and the hfe's are around 120 and the leakage is around .3 on all the ac125 transistors.
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