Adding buffered out to mini-booster

seanm · November 12, 2005, 12:34:05 AM

I am building a small preamp based on the mini-booster. I would like to add a tuner out. The tuner will be a Boss TU-2, so it is fully buffered on the input.

Does anybody see any problems with the following circuit fragment? Vout is the normal amplified output and Vout2 is the buffered tuner out.

amz-fx · November 12, 2005, 01:31:54 AM

It won't work for numerous reasons, for example, Vout is connected to the power supply and would not provide a signal.

Use the buffer off the Dr. Quack circuit and just add another 10uf on the output (source) of the jfet in parallel with the existing one:

http://www.muzique.com/schem/projects.htm

regards, Jack

seanm · November 12, 2005, 03:28:22 AM

Quote from: amz-fx on November 12, 2005, 01:31:54 AM
It won't work for numerous reasons, for example, Vout is connected to the power supply and would not provide a signal.

Oops, I guess I wasn't clear enough. I tend to be too terse.

Jack, this is the bottom half of your mini-booster, I didn't want to post the entire schematic. So the Vout is actually connected to the constant current source provided by the top jfet, not to the power supply.

So I basically wanted to know if there are any issues with tapping off the source and the drain of the bottom transistor in the mini-booster.

I have built it and it *seems* to work.....

amz-fx · November 12, 2005, 09:20:05 AM

I got it now... the bottom output will be lower level than the upper but if you are only using it to drive a tuner it will be fine.

regards, Jack

seanm · November 12, 2005, 06:25:26 PM

Thanks, that's what I figured but it helps to have some professional feedback.

I am hoping to use the mini-boost, with the tuner out, as a preamp into my power amp for rehersal. No tone controls, no volume controls (except on the power amp). Completely plug and play!

amz-fx · November 13, 2005, 08:31:56 AM

I suspect that it will sound kind of bassy without a bit of tone-shaping... but give it a try.

regards, Jack

seanm · November 13, 2005, 01:48:06 PM

Quote from: amz-fx on November 13, 2005, 08:31:56 AM
I suspect that it will sound kind of bassy without a bit of tone-shaping... but give it a try.

regards, Jack

Yes it does sound kind of bassy

I am using it with a bass and it gives a nice warmth. It might be too much, we'll see. What sounds good in the bassment does not always sound good in a band situtation.

seanm · November 16, 2005, 07:51:45 PM

A new but related question. I would like to add a mute that would still allow the buffered out (Vout2) to work. Would shorting Vout between the cap and resistor to ground cause any problems?

I tried it and it seems to work, but I don't want to find out I am putting a huge load on the jfets or some such problem

amz-fx · November 16, 2005, 08:05:24 PM

Quote from: seanm on November 16, 2005, 07:51:45 PM
A new but related question. I would like to add a mute that would still allow the buffered out (Vout2) to work. Would shorting Vout between the cap and resistor to ground cause any problems?

I tried it and it seems to work, but I don't want to find out I am putting a huge load on the jfets or some such problem

It isn't too much load... if your tuner is still reading the signal, go with it.

regards, Jack

seanm · November 16, 2005, 08:35:01 PM

Quote from: amz-fx on November 16, 2005, 08:05:24 PM
Quote from: seanm on November 16, 2005, 07:51:45 PM
A new but related question. I would like to add a mute that would still allow the buffered out (Vout2) to work. Would shorting Vout between the cap and resistor to ground cause any problems?

I tried it and it seems to work, but I don't want to find out I am putting a huge load on the jfets or some such problem

It isn't too much load... if your tuner is still reading the signal, go with it.

regards, Jack

Cool! Thanks.

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Adding buffered out to mini-booster