Built a simple buffer, but losing some volume/tone. Could this cap be issue?

[Jamez0r]

Hey guys, I am a novice pedal builder and decided to build this buffer out of some spare parts I had laying around: http://www.beavisaudio.com/techpages/Buffers/Buffer_OrmanTransistor.gif

I plugged it in, and noticed that I seem to be getting some loss of volume/tone. I triple checked my circuit layout and know that everything is in the correct place, but also then noticed that the cap I used for C2 is a BI-POLAR electrolytic capacitor. I didn't even know those existed, since I had built the buffer out of some spare parts including parts that my friend gave me, I assumed all electrolytic capacitors were polarized (I assumed the longer lead was the positive side).

Could this be the issue causing my volume/tone loss? If so, could someone explain what is going on electrically when I use a bi-polar cap instead of the correct polarized one? I'd say I'm losing about 20% volume and a lot of the treble.

Thanks a lot!

[GibsonGM]

No.

That cap should be fine....think of it as 2 electrolytic caps back to back, if you want...it simply has no polarity.   Works either way.  I like them, and use them instead of polarized where possible with no problems, ever.  They just don't need to be oriented a specific way for the dielectric to function, is how I understand it.  Polarized ones DO need that.

Now, it COULD be 'dead', and that may contribute to what you're saying, but that's reaching.

What are your voltages, per the "debugging thread"?

What are you using for a FET?  You SURE that 1M resistor is actually that value?  If not, that would totally explain your problem....so may having the FET pinout wrong.   

Look for Cap> resistor >FET >resistor >Cap   cuz if you have  'cap > resistor to gnd' on the output, there's another way to have loss of highs....this stuff is nearly *always* a small error we made!   Gotta hunt them down! 

[therecordingart]

I'd double check your resistor values. While the high pass filter formed by the relationship between C1 and R1 by itself wouldn't cause high freq roll-off....loading the pickups with a small value of R1 would. You sure you didn't use a 1k resistor instead of 1M? You'd be looking at a little more than 20db of signal loss assuming 15k pickup impedance trying to drive a 1k load.

EDIT: You said 20% and not 20db. Even if you used a 10k resistor for R1 you'd see roughly 8db of signal loss.

[PRR]

The circuit (with 100K source and 100K load) has bandwidth of 2Hz to 2MHz (far more than guitar), but midband gain of just 0.78.

This is shockingly in-line with your observed "20% loss".

No simple fix. In fact much of the "loss" is any significant source impedance against the 1Meg resistor.

This can be raised to 10Meg or 22Meg.