Page 1 of 1
D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 14 Apr 2012, 14:36
by beedotman
Yo!
Here's one of the latest D*A*M custom one off -
B-13 BOOST.
It was drawn based only on one gut shot, so there's few unconfirmed component values, but I think it could be prettey much OK and should work fine.
It's slightly modified D*A*M red rooster with added switchable output capacitor (F.A.C rotary switch).
It's sports rare White Jacket Mullard OC81D - PNP germanium transistor, so it has positive ground.
Standard for rangemaster bias string 470K/68K was changed and it could be 470K/56K (56K for sure, as seen on gut shot).
Bias resistor on emitter could be 3k9 or something close to it for correct transistor bias.
Values of caps on F.A.C switch are also not confirmed, but more or less should be ok.
Enjoy!
b.man
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 14 Apr 2012, 19:15
by sinner
Something wrong here, circuit board have no V+ connected
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 14 Apr 2012, 20:13
by phibes
Boost and Filter labels are swapped too. I was wondering why it wasn't making sense in my head schemo wise.
I like your guys drawings a lot but you should start adding a schematic with em when ya draw it out. Would make it easier to spot stuff.
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 15 Apr 2012, 05:20
by sinner
phibes wrote:
I like your guys drawings a lot but you should start adding a schematic with em when ya draw it out. Would make it easier to spot stuff.
I was thinking to do that, you know, A4 printable friendly sized, with schemo, but I'm waiting for final DIYLC v3, not all schemo symbols are in it
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 15 Apr 2012, 07:08
by phibes
Check out good ol Express Schematic. It's free, everything's in there and you can modify everything to your liking.
Good plan on the printer friendly part. I print to pdf from express schematic at standard size so it makes for a smooth vector print across all different printers.
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 15 Apr 2012, 08:07
by beedotman
sinner wrote:Something wrong here, circuit board have no V+ connected
phibes wrote:Boost and Filter labels are swapped too. I was wondering why it wasn't making sense in my head schemo wise.
I like your guys drawings a lot but you should start adding a schematic with em when ya draw it out. Would make it easier to spot stuff.
Thanks for correction guys!
Hope now it's OK.
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 15 Apr 2012, 08:09
by beedotman
Schematics is very good idea, will drawn it later today and post here.
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 15 Apr 2012, 11:09
by beedotman
Here's schematic.
I think I dont like ExpressSCH...
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 15 Apr 2012, 15:12
by Bill_Mountain
So elegant in its simplicity.
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 15 Apr 2012, 15:54
by Dr Tony Balls
But why do a cap blend at the input and a FAC control at the out? Both do the same thing....you might as well have FAC/FAC or Filter/Filter. I have been putting FAC style control at the front of my rangemasters but leaving the output cap stock.
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 15 Apr 2012, 18:12
by beedotman
Dr Tony Balls wrote:But why do a cap blend at the input and a FAC control at the out? Both do the same thing....you might as well have FAC/FAC or Filter/Filter. I have been putting FAC style control at the front of my rangemasters but leaving the output cap stock.

Who knows... Pedal owner wrote on D*A*M forum that F.A.C switch changes are very subtle... Personally I don't like input cap blend via pot. Switchable capacitors on input works better IMO.
Re: D*A*M - Germanium Pre-Amplifier B-13 BOOST
Posted: 16 Apr 2012, 18:24
by Bill_Mountain
Dr Tony Balls wrote:But why do a cap blend at the input and a FAC control at the out? Both do the same thing....you might as well have FAC/FAC or Filter/Filter. I have been putting FAC style control at the front of my rangemasters but leaving the output cap stock.
I thought I posted this earlier but I must not have hit submit or something. Anyways…
I quite like the use of two different filter topologies in this design. Also, I can totally see a need for controlling bass in and out of the circuit.
I’m not a D.A.M. fan boy (or even a guitarist) but something about this design strikes me as fun and inviting.