I recently completed a preamp, complete with headphone amp. It sports 3 inputs and 2 outputs, plus a pass-through set of RCA jacks. I have built this from a combination GlassWare Audio SRPP+ board and Pete Millet headphone amp, using the SRP1 aka Nu-Tube by Korg. Also, it made sense to spare no cost for the power supply in this case, and I chose the GlassWare Audio PS-21 for that. This means that the preamp and headphone amp are on separate 12 volt supplies, and that the high voltage supply is of course separate from those. I can go into more detail for those who are interested. I will say that ASR did test the SRPP+ circuit (for headphone, not preamp, but using the same 12AU7 tubes), and found this to be some of the best quality around. It is capable of 20 volts of output, but in this case, it is used as a preamp, and I suspect that no more than 2 volts would be used to supply the power amp. >>>>>>> Ummm, oh yah, the price started at $2,200 + shipping, but that will be negotiable.<<<<<<<<<<
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After about 1/2 hour of warmup, the performance is just what I expect from GlassWare Audio. It has this certain rightness to it.
I will be relisting this unit at near zero profit >>>($1,300)<<< on US AudioMart sometime soon in the near future. What I mean is that I won't be charging for my labor for the drilling, engraving, wiring, soldering, and anything else. This price is the cost of parts including consumables.
Although this unit is listed at Audio Mart for $1,500, anyone here can purchase it for the $1,300 price stated here. This site has done much good for me in audio and I would like to pay it forward (sorta).
They are from Raytheon. As you are likely aware, the 12AU7 is a lower noise/gain than the 12AX7 tube.
nice. what variant raytheon 12AU7?
yes, lower gain (17 or 20mu vs 100 for 12AX7, 70 for 5751, 60 for 12at7 and so on...), lower plate resistance, higher transconductance, but not necessarily lower noise.
yes, lower gain (17 or 20mu vs 100 for 12AX7, 70 for 5751, 60 for 12at7 and so on...), lower plate resistance, higher transconductance, but not necessarily lower noise.
Hmm, I guess that I don't know variant means when talking tubes. I could take the top off and look, but I do not recall any additional lettering such a Y or G or anything other than 12AU7 on these tubes.
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It is 'make an offer' time. Money/trade, stuff like that. I am pretty easy to work with. Need a pair of Mark Audio 12P drivers, Goldpoint or similar attenuators.