I'm thinking through a future speaker project and I will need some sort of pre. I could probably live without any gain, but a little bit wouldn't hurt. My El-Cheapo (PP 6V6) has a great gain structure for most sources, but I could occasionally use a couple more db for really wimpy sources and low recording levels. I'll need the pre to drive two stereo amps or a stereo amp and two mono amps with long interconnects. I would like the flexibility to put simple passive filters between the pre and amps. That is also why a little gain would be nice. I don't know that I have spare enough spare gain to deal with insertion losses of such things.
I have a half dozen used but good 12B4's in an old Tek Scope. I could probably scrounge most of a power supply from the parts bin as well. I like the idea of the 12B4, but are they the best thing for low gain and decent drive? As always, I'm looking for something simple and cheap. Though I can breadboard P2P CCS's and such, I'd rather not if it isn't necessary. And I'd like the whole thing to be pretty small. Biamped OB's could be a tough sell aesthetically.
I also have a sleeve of nice op amps and a good spare regulated supply that could drive them. Those are tempting me as well, but I'd rather stick with a simple tube circuit.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
I have a half dozen used but good 12B4's in an old Tek Scope. I could probably scrounge most of a power supply from the parts bin as well. I like the idea of the 12B4, but are they the best thing for low gain and decent drive? As always, I'm looking for something simple and cheap. Though I can breadboard P2P CCS's and such, I'd rather not if it isn't necessary. And I'd like the whole thing to be pretty small. Biamped OB's could be a tough sell aesthetically.
I also have a sleeve of nice op amps and a good spare regulated supply that could drive them. Those are tempting me as well, but I'd rather stick with a simple tube circuit.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
yup ;
that schematic - my contribution was just calculating values for simplest shunt reg ;
take a look in Salas's 6V6 line preamp thread ....... maybe you'll change your mind regarding simple bits 'n' pieces .......
anyway - hardware is most complicated ..... electronic parts are simple .... sort of .
12B4 with gyrator in anode and decent (discrete) CCS in cathode will blow plain resistor loaded stage ....
PJ,
There are more 12B4 designs than you can shake a stick at. The 12B4 is a nice tube. How many triodes are available that can drive the NASTY IHF "standard" load from the anode? 😉
FWIW, I've uploaded my version of a 12B4 line stage. Suitable power transformers are inexpensive Triad brand. The filter chokes will cost you some cash. You can forego the "boutique" parts shown. Buzz, a buddy of mine, who favors costly parts, made that drawing from a narrative I provided.
There are more 12B4 designs than you can shake a stick at. The 12B4 is a nice tube. How many triodes are available that can drive the NASTY IHF "standard" load from the anode? 😉
FWIW, I've uploaded my version of a 12B4 line stage. Suitable power transformers are inexpensive Triad brand. The filter chokes will cost you some cash. You can forego the "boutique" parts shown. Buzz, a buddy of mine, who favors costly parts, made that drawing from a narrative I provided.
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Eli, I pay close attention to most of your posts. I bookmarked that schematic about the day after I picked up all the 12B4s!
It sounds as the various 12B4 circuits are well suited to my needs. I do like the idea of four 0D3's, and I've already got enough power transformer (I think). You know how I like big shiny things. Though we both know what a PITA my last cobbled together PS turned out to be (I think the swinging choke is now buzzing loudly when it saturates/swings). I have a few chokes too, at least a 5H or 10H (depending on which I leave in the EC) but there are three that I need to measure. I have a few more motor runs too. Now I have something to ponder over the holidays.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
It sounds as the various 12B4 circuits are well suited to my needs. I do like the idea of four 0D3's, and I've already got enough power transformer (I think). You know how I like big shiny things. Though we both know what a PITA my last cobbled together PS turned out to be (I think the swinging choke is now buzzing loudly when it saturates/swings). I have a few chokes too, at least a 5H or 10H (depending on which I leave in the EC) but there are three that I need to measure. I have a few more motor runs too. Now I have something to ponder over the holidays.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
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