Easy face-problem

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makispoll
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Post by makispoll »

Hi guys!!!! First of all congrats to everyone for contributing to an amazing forum for DIYers and musicians. Let's move on to my question. I have recently built and Easyface. The problem with is that I get a nice fuzzy sound but it is way too low volume...My ac128 transistor is about hfe81-90 accornding to the store i got it. Is it too low gain or is it something else? Here's the layout I used:


https://img593.imageshack.us/f/easyface.gif/


Thanks!
Makis

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lolbou
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Post by lolbou »

makispoll wrote:My ac128 transistor is about hfe81-90
You mean both?
makispoll wrote:accornding to the store i got it
Which store? Better off checking these yourself with GEOFEX method... :wink:

Did you tweak the trimpot somehow?
- Are you a mod or a rocker?
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makispoll
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Post by makispoll »

Thanks for your reply. I bought them from Banzai. The Ge transistor has hfe 81-90 no idea how much is the Si. This easyface is a hybrid of Ge-Si transistors. I also checked and swapped them and turned them upside down. I tweaked the tripod and it's set at maximum in order to get that wee sound. What do you think is the best hfe value of the transistors in order to get it sound properly? Do you think that low hfe gives low volume or low gain or....both?

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azrael
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Post by azrael »

Low volume how? Like...weak? Or just not enough volume for your tastes?

Have you measured the collector voltage on Q2? Should be around 4.5V.

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makispoll
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Post by makispoll »

Extremely low...that's not normal... I don't have a multimeter, I'll try to get one if that could solve my problem. Do you think that this weak volume is not caused by the low hfe transistors?

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azrael
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Post by azrael »

No, the recommended gains in a pure germanium fuzz face are 70 for Q1 and 100 for Q2. You're in the ballpark.

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makispoll
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Post by makispoll »

I have ordered some alternative Ge transistors. I will try those when they arrive... If there will be no improvement will try with a multimeter. As for they layout do you think there is something wrong in terms of values or connections? I compered it to the schematic and to me it looks ok but I'm not that experienced.

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Post by mictester »

makispoll wrote:Hi guys!!!! First of all congrats to everyone for contributing to an amazing forum for DIYers and musicians. Let's move on to my question. I have recently built and Easyface. The problem with is that I get a nice fuzzy sound but it is way too low volume...My ac128 transistor is about hfe81-90 accornding to the store i got it. Is it too low gain or is it something else? Here's the layout I used:
https://img593.imageshack.us/f/easyface.gif/
Thanks!
Makis
The gains of the transistors will not affect the output level - it just changes the amount of fuzziness. Change the 470 ohm resistor for 1k and you'll get much more level out, but you'll have to adjust the trimmer again to get rid of any "gating".
"Why is it humming?" "Because it doesn't know the words!"

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Post by DrNomis »

I've even substituted a 4.7K resistor for the 470 Ohm to give lots of output.... :)
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makispoll
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Post by makispoll »

DrNomis wrote:I've even substituted a 4.7K resistor for the 470 Ohm to give lots of output.... :)

4k7? That's 10times more resistance! Did you use the same schematic as me apart from the 4k7-470R swap? Did you face the same low level problem initially?

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makispoll
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Post by makispoll »

SORTED!!!! Thanks everyone for your help!!! The problem was different though.....

I inspected the traces and cleaned them and discovered a tinny "hair" thick solder connecting two copper stripes :oops: :oops: :oops: :oops: . That little think caused everything. So no need for changing resistors it works great with those values!!!!! I can confirm that with a 2N2907A for Q1 and AC128 hfe 81-90 for Q2 the pedal sounds great!!! It definitely worths building it!!!!

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