Build Your Own Clone Message Board

Hi,

Some time ago, I built the 2-knob bender kit with the VAL 076 Ge transistors. However, I have neveu been convinced by the sound... The pedal tends to sound harsh and thin and volume is week compared to bypass sound when dialed in at noon on the pots.

I checked the HFe of the 3 Ge's and they read 90 for Q1, 150 for Q2 and 165 for Q3. I measured those figures after the transistors cooled down to ambiant temp ~23°C (~73°F).

Is this all to be expected with this fuzz ?

I especially wonder if it's worth replacing the OC76 with OC75 with HFe's within specs.

I thank you in advance for your help,

Regards,
Cesar

Those numbers look quite reasonable, but unless you are also measuring and adjusting for transistor leakage (which tends to be quite significant with Ge transistors), the HFe values you measure will be artificially high. BYOC has always been careful to only use Ge trannies with low leakage, but there's always some present. Much more on that topic here: viewtopic.php?f=9&t=38231

It would be a good idea for you to post photos of your build so that we can see if anything pops out that could contribute to this issue. Such photos need to be LARGE, well-focused and well-lit and show both sides of the PCB and all of the jack and switch wiring.

BTW, where does the pedal sit in your signal chain? Fuzzes of this type are notorious for sounding poor if they are behind a buffered pedal, so it is often recommended that they be the first pedal in your chain. Does it sound any better if you run just guitar --> Bender --> amp?

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Hi,

Thank you very much for adressing my concern, this is very kind !

I didn't know about the leakage causing a bias in the HFe measurement.

Regarding buffers, I knew that fuzz circuits reacted in a fancy way with buffers. In my case, I always used the bender alone with straight jacks from guitar to bender then from bender to amp.

Maybe I am too demanding and what I hear is part of the sound. But the gain is very high at sero setting and there is quite an harshness (way trebly than a BC108 fuzzface I also have) whith a volume drop when evrything is set at noon no matter the trimpot setting.

Here are some pics as you suggested,

Regards,
Cesar

P.S. : Remaining pics

How does the trimpot affect the tone for you? Can you measure the voltage on the collector of Q3 and report that here?

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Well, fully clockwise, the tension between Emettor and Collector is V_EC ~ 1V, the sound level is low and the tone is thin.
When set fully counter-clockwise, the tension is now around V_EC ~ 8.5V and the sound is louder and warmer but becomes a bit gated when I roll off my guitar volume. Therefore, I set it a bit off and get V_EC set around 7.4V (same trim position as on the picture).

Thanks again,

Regards,
Cesar

For what it's worth, the following is what I find on my own ESV Bender, which is the same version as yours. Mine has the Philips black casing OC75 transistors which are what came in my kit.

My DC adapter power source measures 9.96V. With the trimpot at full CCW, the Q3 collector measures -9.9V. The fuzz effect is muted and sustain is reduced, but the output is loud with good bass content, and unity volume is at about 9 o'clock on the volume control. At full CW, the Q3 collector voltage is -8.4V, with unity volume at about 2 o'clock and a much thinner sounding fuzz tone with long sustain. My preferred tone is with the trimpot set at about 10:30. At this point, the Q3 collector voltage is -9.4V, unity volume is right around 12 noon on the output control, and the tone has a good mix of fuzz, sustain and bottom end. But what sounds "best" is, of course, very subjective.

You might want to try swapping Q2 and Q3 and just see if that makes any noticeable difference for you.

What kind of power source are you using and what is its output voltage?

There are MANY demo videos for the ESV Fuzz on YouTube. Have you listened to some those to compare them to your pedal? Here's a good one that compares different bias trimpot settings:

https://www.youtube.com/watch?v=989G1C2chmw

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Hi,

Thank you for your answer !

I tried a swap between Q2 and Q3 but it di nto make much of a difference though. Unity volum is got with level set on 3 p.m and sound remains pretty trebly. Q3 collector still reads around 7.5V.

My DC power supply reads 8.97V which is very accurate !

I think I cannot do much. It is quite surprising you can get that much difference in the electrical behavior (Q3 collector voltage and volume range).

I think I have to stick to the tone I get from this particular kit or... let's be mad... should I give a try to run the bender at 18V DC ?

Thanks again,
Regards,

César