B1 preamp build thread

Hi All,

My son wants to build a B1 & will be ordering the board + JFETS from PassDIY. Regarding the power supply, how sophisticated does it have to be? In the B1 article NP suggests that regulation is not necessary, but what is needed in the PS? Based on what we have on hand, I'm thinking a rectifier (monolithic), a couple of 3300uF capacitors, and a bleeder resistor. Will this work? If so, what am I sacrificing by taking this minimalistic approach? The transformer is a 15V toroid I got at the electronic surplus store for $3 (I picked up a few).

Thanks...
 
I have a strange behaviour here: just assembled a B1 with old JimsAudio boards I had available. These boards have a layout problem with the connection s but I fixed it.
The buffer works correctly but... led does not light.
I thought it was simply blown but it is not.
Checking voltage on the led I have only 0.4V there and it seems not enough to power the led.
Is it correct..?
 
LEDs need to have Vf across them to pass sufficient current to light them up.
Vf varies from ~1.4Vf for an IR type to ~3.3Vf for a white or blue type.

None will pass enough current at a voltage of ~0.4Vdc

Thanks.
I do not worry too much about the led not working there since it's only a status led without any other purpose. But I would like to have a signal of the buffer with current on: where could I drain those few volts in order to make it work with no damage for the buffer functionality?
 
Here is my B1. Rather compact! Less noise I hope, because it was a b**** to fit everything. Will change the wall wort for a battery soon.
The sound is much better than with just a pot. It took me two days to build it. First days of Easter vacation and I am already done. Now what to do?
 

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6L6, finally implemented your version of the power supply last night. I find it made a considerable improvement over the lap top style power supply I bought off of Ebay. It also was considerably better than the Duracell battery setup I cobbled together. Didnt help with gain of course, was listening full throttle with the 86 db speakers that were at hand in that room. Sound was way better than before...I still prefer a little gain with the F-5, which I was using. But sound was much more full than before.

For those of you using similar supplies, try the little regulated version 6L6 uses in this build!

Russellc
 
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Joined 2003
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Scroll back to the beginning, 6L6 provided a list of parts (not very many at all) and gives the source for the board (Peter Daniels) although it would be simple to point to point. With my Lap top supply, it was transparent, but no body at all. With the little regulated supply, it is full with a richer sound. Better to me in every regard. I had relegated it to disuse until this.

Russellc
 
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