Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jeff on April 24, 2012, 08:18:16 pm
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Is a tube preamp compatable with a solid state power amp.
I was thinking of building a tube preamp for my bass amp. Can I simply add a jack after the preamp(where it would normally go to the phase inverter of the tube amp) and plug it into the "power amp in" of my solid state bass amp or do I need something between the tube pre and SS power amp?
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Of course. In the schematic you posted, just jack out at terminal 1.
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Looks like you're going to have to build a "self-contained" 480-485v power supply for the preamp as well and also supply filament voltage. Will it be easy to find a toroidal inductor for the midrange selector?
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>Will it be easy to find a toroidal inductor for the midrange selector?
I've been down this street already. the short answer is no. PRR coaxed me through some experiments using some cheap off the shelf inductors. Happily I gained knowledge but sonically it fell quite short. I never quite ventured into the "roll your own" inductor game but that's pretty much the only route. I couldn't find a winder who'd tackle it with a clear conscience due to costs. Now that I think about it, my venture into LC tone circuitry may have been Mesa Mark 2 related and I simply rolled my eyes when I fediddled with the SVT preamp. Regardless, channel 2 is kewl. Here's a link to what I ultimately built and still use. It's a "go to" preamp at Yellow Dog Studios. I built 8 of them and 6 of them are in regular use, 1 unknown, and 1 has been hacked for Rev B using a modern (not vintage) output transformer.
http://www.sotxampco.com/Schematics/STAC/Chanel-B-8.pdf (http://www.sotxampco.com/Schematics/STAC/Chanel-B-8.pdf)
BTW: R23 has been replaced with a 100k fixed resistor and a 1M audio pot in series so as to give the balanced output a 0 to 21dB attenuator.
(http://www.sotxampco.com/Images/Kelsey-Board.jpg)
(http://www.sotxampco.com/Images/KB02.jpg)
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Wow! Looks top shelf to me Richard. Bet it sounds great too. :icon_biggrin:
Brad :thumbsup:
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It's a good circuit. In retrospect, the PCB mounted pots and jack aren't such a good idea. The Par Metals chassis is a little funky with the double front, causing me to have to over bore the jack hole on the outer front plate. Other than that it performs outstandingly. It being a "go to" device in a big league studio here is certainly a feather in my cap. The output time delay relay is a must whereas w/o it, your power amp gets some nastiness when you first light it up.