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A DIY Tube Preamp/Line Driver by Passinwind

#82
beans-on-toast said:
Let us know how good it sounds once you've had a listen.
Click to expand...

Got to play through it for a solid hour or so; so far it sounds like a "tubier" version of the first one, as planned. Great noise floor, no microphonics, pretty much ready for prime time. :bassist:

With that kind of signal level, maybe you should try driving some headphones.

Lots of people use the same Aikido circuit for driving cans. A 6SN7 (or two) can do that really well.

First front panel pic. Dunno if the owner wants his name online, so I pixied it:

DESE_2.jpg


DESE_backin.jpg
 
#84
Good to hear that the debut went well. Hope that the owner enjoys it.

The pre-amp is built so solidly. It looks like it could be dropped on the floor and not miss a heartbeat.

I use PEC pots and like them a lot. It looks like that is what you are using.
 
#87
Charlie, are you happy with the PS-14 power supply? Did you consider using the PS-1? It might be too regulated. I'm starting to think about a DI/ headphone amp design. My first thought was to use the PS-14.

I came across [Invalid or Expired Link Removed] toroid shield. It looks interesting.
 
#88
beans-on-toast said:
Charlie, are you happy with the PS-14 power supply? Did you consider using the PS-1? It might be too regulated. I'm starting to think about a DI/ headphone amp design. My first thought was to use the PS-14.

I came across [Invalid or Expired Link Removed] toroid shield. It looks interesting.
Click to expand...

Actually, I only got to play through that preamp for a day or so -- I took it to one of my friend's gigs for an audition and we worked up a wish list for a few mods during a long pre-gig test. But then after his first set he whipped out his checkbook and I haven't heard a word from him in the last month...;)

The PS-14 has the long and skinny form factor I preferred/needed, but the PS-1 has the filament voltage lift circuit built in, which would have been handy. In all honesty, I bought the first one that came into stock, as Mr Broskie tends to do short runs that sell out frequently. If there's a next time (ha!) I will likely do my own power supply board, I guess. Cramming all that stuff into 2RU is a bit dodgy and rolling my own could help that a little.

Thanks for that link David. I've used sheet metal "wings" before, but that solution looks a lot nicer and would probably also work better.
 
#89
beans-on-toast said:
Good to hear that the debut went well. Hope that the owner enjoys it.

The pre-amp is built so solidly. It looks like it could be dropped on the floor and not miss a heartbeat.

I use PEC pots and like them a lot. It looks like that is what you are using.
Click to expand...
I was planning to these in a new build. Then I ran across this forum posting about noisy PEC pots. Has anyone else experienced this problem?
 
#90
Codger said:
I was planning to these in a new build. Then I ran across this forum posting about noisy PEC pots. Has anyone else experienced this problem?
Click to expand...

I have with the conductive plastic ones, but so far not with the molded carbon version. The last batch I bought were marked Made In Mexico and the wafer section looked different, FWIW.

I've had terrible luck with the new Alphas that people in that thread seem to like so much, and consider them a last resort really. These days I tend to look for surplus OEM pots from known high quality builds like old Haflers, etc.; usually they're Bourns, A-B, Noble, or Alps.
 
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#91
Codger said:
I was planning to these in a new build. Then I ran across this forum posting about noisy PEC pots. Has anyone else experienced this problem?
Click to expand...

I've never experienced a problem with them. Maybe I've just been lucky or maybe the quality is changing. The ones that I use are made in Canada.

Dating way back, RV4 type sealed pots are used in studio, test equipment, and military gear that I work with. They have a long service life. The pots can be disassembled for cleaning if need be. There are four tabs that you bend back and off pops the back case. Same thing that you do for a rheostat type pot that is commonly used for heater hum balance on some amps.

The CTS, Bourne, and Alpha instrument pots are good as well. They've got a good track record in instruments, amps , and pedals. Here is a Bourne linear 1M that I've used in SVT's available from Digikey.com PDA241-SRT02-105B0-ND. They have the data sheet available. Originally those amps had CTS pots.
 

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