Sola Sound - Tonebender Mark II Professional  [schematic]

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

NKT275 sounds great in MKII! :thumbsup
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Post by copachino »

beedotman wrote:NKT275 sounds great in MKII! :thumbsup

where did you get thos transistors??? small bear only gave me a cumple of no name stransistor, supposed to be made in US.

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Post by jalmonsalmon »

You can get NKT275s off of ebay. Never tried those in a tone bender before... Nice :mrgreen:

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Post by beedotman »

yup, ebay.

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Post by copachino »

i have a problem with my god bender jejeje, i sounds like hell, really zeppeling sound but, alone, if i plug it into my chain its sound like crap, this its my chain for my zeppeling rig.


chromatic tuner-----full tone wah----whammy-----tonebender-----ep booster----- amp
amp fx loop------ wayhuge aqua puss----t rex chorus----boss ce2(moded by robert keleey)----

i have tried to put it averywhere, but nothing happens, even if the pedal its before the ep booster, when i use the booster, i changes the sound to an almost high gain distortion...

any help???

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Post by iq01221 »

Put it first in the chain, just after the guitar. The cause of the problem are the buffers cointained in the tuner, wah and the wahmmy.
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Post by copachino »

iq01221 wrote:Put it first in the chain, just after the guitar. The cause of the problem are the buffers cointained in the tuner, wah and the wahmmy.
Best regards!!
direct from the guitar has the same problem, im not so sure what happens, maybe its mi supply that has a preamp on it....

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Post by Masuto »

Hi Electric Warrior, Beedotman, Jamonslamon, and fellas, it's tonebender mkii building time again!
A friend of mine, whom i gifted with my very first oc75 build, was recently recording at a very nice local studio, and guess what, the engineer was stunned at the pedal. Pure violence, he said. So i decided to build some more. That was a perfboard build, now i mainly go for the Electric Warrior vero layout. I also won a huge ebay auction and some funny valvos (oc74, oc77, oc79..) are on the way. In the meantime, i got to really listen close to the differences between my oc84 and oc75 builds.. The oc84 is somewhat very 'coherent', as in steady, nice mids, great for rhythm guitar.. Whereas..well.. 'The oc75 SINGS. It breaks up in a wholesome lyrical, gracious way, a nice way to trail those notes to an end.. I am afraid to say it, but it appears that oc75's, those bastard expensive threesomes, are the go to trannies for this pedal. But lets wait till i get those valvos in, and i'll report.
Always a great read, fellows.

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Post by copachino »

Masuto wrote:Hi Electric Warrior, Beedotman, Jamonslamon, and fellas, it's tonebender mkii building time again!
A friend of mine, whom i gifted with my very first oc75 build, was recently recording at a very nice local studio, and guess what, the engineer was stunned at the pedal. Pure violence, he said. So i decided to build some more. That was a perfboard build, now i mainly go for the Electric Warrior vero layout. I also won a huge ebay auction and some funny valvos (oc74, oc77, oc79..) are on the way. In the meantime, i got to really listen close to the differences between my oc84 and oc75 builds.. The oc84 is somewhat very 'coherent', as in steady, nice mids, great for rhythm guitar.. Whereas..well.. 'The oc75 SINGS. It breaks up in a wholesome lyrical, gracious way, a nice way to trail those notes to an end.. I am afraid to say it, but it appears that oc75's, those bastard expensive threesomes, are the go to trannies for this pedal. But lets wait till i get those valvos in, and i'll report.
Always a great read, fellows.

my god friend can you tell me where to get a set of 0c75??, i have a generic from small bear but im not so sure, i have tried biasing but, still something just not right, the pedal has a great gain but somehow, sounds a bit darker ansd has more bass than thew original sound
i have measssure, and here are my voltages on max and min gain

at min:
Q1:-8.38V
Q2:-0.589V
Q3:-7.7v

at max gain:
Q1:-8.38V
Q2:-0.4V
Q3:-7.73v
im using -9.38V .... still sound like to much bass, i think it has a good sound but i has to much lows, sounds like too dark, and the vintage unit sounds more sharp, perhaps i have to lower even more Q2, and upper Q3??, but im not so sure about Q3, it has already a 2,2Kresistor on it, so i dont want to get damage

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Post by LucifersTrip »

copachino wrote:
at min:
Q1:-8.38V
Q2:-0.589V
Q3:-7.7v

at max gain:
Q1:-8.38V
Q2:-0.4V
Q3:-7.73v
but im not so sure about Q3, it has already a 2,2Kresistor on it
I believe that's the problem. if you alter (lower) the resistor (8.2K) on Q3 collector too much, you will make it more boomy. you can get away with maybe 2K up or down from 8.2K, but not 2.2K. Just alter the resistor on Q2 instead. If you can't get what you like by altering that (and possibly tweaking Q1's base resistor for gain), then try different transistors or flip them around and try a different order.

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Post by copachino »

LucifersTrip wrote:
copachino wrote:
at min:
Q1:-8.38V
Q2:-0.589V
Q3:-7.7v

at max gain:
Q1:-8.38V
Q2:-0.4V
Q3:-7.73v
but im not so sure about Q3, it has already a 2,2Kresistor on it
I believe that's the problem. if you alter (lower) the resistor (8.2K) on Q3 collector too much, you will make it more boomy. you can get away with maybe 2K up or down from 8.2K, but not 2.2K. Just alter the resistor on Q2 instead. If you can't get what you like by altering that (and possibly tweaking Q1's base resistor for gain), then try different transistors or flip them around and try a different order.

i only order a set from small bears(the last they have) but i will try with some resistors on Q2 maybe 60k on Q2 collector, also, do you think by lowering the bypass on q2 and q3 with help??, its on stock 100k maybe 82k or so,

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Post by DrNomis »

copachino wrote:
LucifersTrip wrote:
copachino wrote:
at min:
Q1:-8.38V
Q2:-0.589V
Q3:-7.7v

at max gain:
Q1:-8.38V
Q2:-0.4V
Q3:-7.73v
but im not so sure about Q3, it has already a 2,2Kresistor on it
I believe that's the problem. if you alter (lower) the resistor (8.2K) on Q3 collector too much, you will make it more boomy. you can get away with maybe 2K up or down from 8.2K, but not 2.2K. Just alter the resistor on Q2 instead. If you can't get what you like by altering that (and possibly tweaking Q1's base resistor for gain), then try different transistors or flip them around and try a different order.

i only order a set from small bears(the last they have) but i will try with some resistors on Q2 maybe 60k on Q2 collector, also, do you think by lowering the bypass on q2 and q3 with help??, its on stock 100k maybe 82k or so,


What value of resistor did you use for Q2's collector resistor?, if you used either a 100k, or a 47k, you could try a 33k and see if it sorts things out...... :thumbsup
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Post by copachino »

i tried a 33k first but q3 voltages was lower, so i used 47k(stock mkII) and q3 got about 8.5V now, so maybe i can increase the Q3 collector up to 6k and maybe a bigger resistor on Q2 will mae things better, but was talking also the bypass(not so sure how to call it) in te Q3 Emiter and Q2 base that its a 100k i remember that from small bear diagram that resistor was 47K(not so sure why), but i decided not to used since Q3 collector was aim to -4.5V and you guys told that Q3 has a bigger value, im sure that i need to lower Q2 a bit more almost at -0.2v or so

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Post by DrNomis »

copachino wrote:i tried a 33k first but q3 voltages was lower, so i used 47k(stock mkII) and q3 got about 8.5V now, so maybe i can increase the Q3 collector up to 6k and maybe a bigger resistor on Q2 will mae things better, but was talking also the bypass(not so sure how to call it) in te Q3 Emiter and Q2 base that its a 100k i remember that from small bear diagram that resistor was 47K(not so sure why), but i decided not to used since Q3 collector was aim to -4.5V and you guys told that Q3 has a bigger value, im sure that i need to lower Q2 a bit more almost at -0.2v or so

That 100k resistor going from Q3's emitter to Q2's base is what's called a "Negative-Feedback" resistor, it's job is basically to tame the huge gain of the Mk II circuit when the Attack control (1k B pot) is set to minimum, when you increase the Attack control the 4u7 (5uF) cap going from the wiper to ground gradually shunts the negative feedback signal to ground, thus letting the circuit operate with more gain..... :thumbsup
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Post by copachino »

DrNomis wrote:
copachino wrote:i tried a 33k first but q3 voltages was lower, so i used 47k(stock mkII) and q3 got about 8.5V now, so maybe i can increase the Q3 collector up to 6k and maybe a bigger resistor on Q2 will mae things better, but was talking also the bypass(not so sure how to call it) in te Q3 Emiter and Q2 base that its a 100k i remember that from small bear diagram that resistor was 47K(not so sure why), but i decided not to used since Q3 collector was aim to -4.5V and you guys told that Q3 has a bigger value, im sure that i need to lower Q2 a bit more almost at -0.2v or so

That 100k resistor going from Q3's emitter to Q2's base is what's called a "Negative-Feedback" resistor, it's job is basically to tame the huge gain of the Mk II circuit when the Attack control (1k B pot) is set to minimum, when you increase the Attack control the 4u7 (5uF) cap going from the wiper to ground gradually shunts the negative feedback signal to ground, thus letting the circuit operate with more gain..... :thumbsup


thanks i wasnt sure about that, now its pretty clear, i will try some resistor when i get home, thanks

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Post by jalmonsalmon »

copachino wrote: my god friend can you tell me where to get a set of 0c75??, i have a generic from small bear but im not so sure, i have tried biasing but, still something just not right, the pedal has a great gain but somehow, sounds a bit darker ansd has more bass than thew original sound
i have measssure, and here are my voltages on max and min gain

at min:
Q1:-8.38V
Q2:-0.589V
Q3:-7.7v

at max gain:
Q1:-8.38V
Q2:-0.4V
Q3:-7.73v
im using -9.38V .... still sound like to much bass, i think it has a good sound but i has to much lows, sounds like too dark, and the vintage unit sounds more sharp, perhaps i have to lower even more Q2, and upper Q3??, but im not so sure about Q3, it has already a 2,2Kresistor on it, so i dont want to get damage
I know when you get a set of TB M2 transistors from small bear, you will get a colorsound schematic with changes to the biasing resistors... You may want to follow those as well and see if that helps out. :hmmm:

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Post by LucifersTrip »

copachino wrote:i tried a 33k first but q3 voltages was lower, so i used 47k(stock mkII) and q3 got about 8.5V now,
This is with the 2.2K on Q3? what do you get with the 8.2K back there? you should get around 7.5-8.5V

did Small Bear instructions tell you 4.5V?

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Post by Electric Warrior »

Not sure if they tell you that it needs to be 4.5V, but users here and an other forums have told me several times that their sets do measure 4.5V on Q3's collector with the supplied resistor values.
The schematic they use isn't correct either. It has a 100k on Q1's base and a 47k on Q2's collector instead of 10k/47k (OC75 version) or 100k/100k (OC81D version).
The range of hfes that come in their sets is really wide. I guess that doesn't make things easier.

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Post by bato001 »

Electric Warrior wrote:Not sure if they tell you that it needs to be 4.5V, but users here and an other forums have told me several times that their sets do measure 4.5V on Q3's collector with the supplied resistor values.
The schematic they use isn't correct either. It has a 100k on Q1's base and a 47k on Q2's collector instead of 10k/47k (OC75 version) or 100k/100k (OC81D version).
The range of hfes that come in their sets is really wide. I guess that doesn't make things easier.
This is why I use those 'new fangled' trimmer thingys on the collector of Q2 and Q3 on my MKII builds, then adjust them to get the best sound rather than shooting for particular collector voltages. :thumbsup
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Post by Electric Warrior »

I tried trimmers and decided I don't need any more options to mess up something that works perfectly fine the way it was designed. But then again I was lucky enough to score a handful of OC75s. All they need is a little swapping transistors around to make it behave nicely. Getting the voltages out of the range reported in vintage units is not easy with these. :mrgreen:

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