B1 Buffer Preamp

[AndrewT]

Originally posted by Nelson Pass


Arrrrr... 'Tis a pitiful preamp that a few micro-amps cannot source,
sez I.

and there are few valve pre-amps with a recommended load impedance of less than 50k.
That is not an invitation to list ten valve pre-amps that can, it's just a statement of the general requirement for many valve pre-amps.

[Tolu]

My power amp needs a bit more "pedal on the metal". So, how can I add around 9-12 dB gain at the B1 or should I wait for B3?

[Floric]

Without the addition of extra parts or a complete change of the topology, the b1 has no voltage gain, it is common drain. So you have to wait for the subsequent models or use the J-BOZ.

With best regards

Flo

[increek22]

Offered here is an image of an alternate single-sided B1 Buffer layout. Input capacitors are axial lead, and pads for up to four inputs are included.

[increek22]

photo of single sided B1 pc board etched at home.

[increek22]

oops, picture was too large. here it is compressed. This board was etched at home using a solution of one part muriatic acid and two parts hydrogen peroxide (3%), and Techniks "press and peel blue" toner transfer sheets to form the etch resist mask.

[vonfilm]

Can anyone recommend a source for the 25K Ohm Linear Taper Mono Pots?

Also a good switch for 4 sources?

Looking for good quality on a budget.

[bubba177]

ebay-i bought 2 mono pots with 24 step discrete resistors for i believe 30 bucks for my b1 and they work great.mouser has a good "cheap" selector switch and parts connexion has a better one or try---you guessed it---ebay

[Nelson Pass]

Originally posted by Floric
Without the addition of extra parts or a complete change of the topology, the b1 has no voltage gain, it is common drain. So you have to wait for the subsequent models or use the J-BOZ.

There is a B3 coming, and it has voltage gain.

[BradJudy]

I've used a Grayhill rotary switch before for input selection and they seem nice. I'll have to double-check, but I think this is the model I used:

http://search.digikey.com/scripts/Dk...name=GH7102-ND