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Old 27th October 2008, 07:46 AM   #811
AndrewT is offline AndrewT  Scotland
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Quote:
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.
__________________
regards Andrew T.
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Old 27th October 2008, 08:47 AM   #812
Tolu is offline Tolu  Germany
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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?
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Old 27th October 2008, 09:06 AM   #813
Floric is offline Floric  Europe
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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
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Old 27th October 2008, 09:42 PM   #814
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Default single sided B1 Buffer Layout

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.
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File Type: pdf pcb design_ b1 buffer image.pdf (36.5 KB, 530 views)
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Old 27th October 2008, 10:44 PM   #815
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Default single sided B1 pc board image

photo of single sided B1 pc board etched at home.
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Old 27th October 2008, 11:25 PM   #816
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Default B1 Buffer single sided pc board image

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.
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File Type: jpg b1 board pix.jpg (40.4 KB, 1820 views)
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Old 28th October 2008, 03:28 PM   #817
vonfilm is offline vonfilm  United States
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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.
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Old 28th October 2008, 04:30 PM   #818
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Location: missouri
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
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Old 28th October 2008, 07:22 PM   #819
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Quote:
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.

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Old 28th October 2008, 08:32 PM   #820
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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
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