I'm thinking about a DIY, stereo, line-level, tube preamp. I not looking for a kit, but I would like more than just a schematic, like: a basic BOM, build instructions, and an active on-line support group/forum. The preamp would replace, and hopefully, be an up-grade for my Mac c-27.
Any ideas, thoughts, experiences, etc. would be very welcome.
Any ideas, thoughts, experiences, etc. would be very welcome.
My thought is that almost all modern domestic audio systems do not need a line level preamp. Exceptions are those with very long interconnects, or poorly engineered sources or amplifiers with unusually high/low (respectively) impedance outputs/inputs or significantly nonlinear impedances (sometimes found in the more expensive 'high end' gear).
Phono source: one lomc phono set-up and a good phonostage; doubt if I would ever have any interest in a moving magnet cart, but, if I did, I would use a separate phonostage. Other sources: one sacd/dac player, but expect that there may additional digital sources in the future; one head headphone amp, one tuner. one tape deck/recorder.
Amp is Macintosh mc-2015 (105/channel).
Size: I expect a finished preamp to be approximately 17" x 12" (+/-). All components are in close proximity. I would expect the build cost (high level audio components, nice chassis and hardware, good tubes, etc.) to be in the vicinity of USD 1500-2000. Optional tube upgrades could increase the cost.
Why tubes, I would like to upgrade my current Mcintosh c-27 preamp and would like "tube sound" in my system. If, at some time in the future, I wanted to up-grade, or add amp power, I would likely choose solid state.
Amp is Macintosh mc-2015 (105/channel).
Size: I expect a finished preamp to be approximately 17" x 12" (+/-). All components are in close proximity. I would expect the build cost (high level audio components, nice chassis and hardware, good tubes, etc.) to be in the vicinity of USD 1500-2000. Optional tube upgrades could increase the cost.
Why tubes, I would like to upgrade my current Mcintosh c-27 preamp and would like "tube sound" in my system. If, at some time in the future, I wanted to up-grade, or add amp power, I would likely choose solid state.
Ok. We are getting somewhere. The question of needed gain/attenuation needs to be answered. And also what you refer to as "tube sound".
"Tube sound" comes up regularly but I am not sure what people connect to that. The same tube amplifier can sound distinctly different when let's say a CRCRC filtered anode supply is replaced for a LCLC supply giving the same voltage.
"Tube sound" comes up regularly but I am not sure what people connect to that. The same tube amplifier can sound distinctly different when let's say a CRCRC filtered anode supply is replaced for a LCLC supply giving the same voltage.
My current preamp has two amps: 14db through the volume control and an additional 6 db related to tone control. As any phono gain would be created and controlled through a separate phonostage, I assume the gain requirements would be in around 20 db.
"Tube sound" is something I cannot, at this stage, discuss with any certainty. It is something that I will have to work-at as I research this project.
"Tube sound" is something I cannot, at this stage, discuss with any certainty. It is something that I will have to work-at as I research this project.
4S Universal Preamplifier for 12A*7 Tubes
DIY ECC802S (12AU7 / ECC82) Vacuum Tube SRPP Preamplifier
I've built and I am using the first one and for me it works great. The 2nd one has better spec's. Both are very simple and are very close to what you asked for in a schematic build. The site also has a forum where you can read about what others have said about the build and help if you have questions.
DIY ECC802S (12AU7 / ECC82) Vacuum Tube SRPP Preamplifier
I've built and I am using the first one and for me it works great. The 2nd one has better spec's. Both are very simple and are very close to what you asked for in a schematic build. The site also has a forum where you can read about what others have said about the build and help if you have questions.
Why have you ruled out kits? In that price range my choice would be this, BeePre 300B Preamplifier Kit | Bottlehead also comes with build instructions, and an active on-line support group/forum too.
@ kaputt - doubt if I need 20 dB; I'm not close to tapping the gain limit of my c-27; but don't yet have a good feel for an optimum level - time will tell. But, it's certainly better to have too much rather than too little power.
@ wdecho - thanks for the leads, I'll digest the information and may have some follow-up.
@ mcandar - I'll certainly check into the kits that you suggest. My experience with kits has been that it's a little like "Paint-by-numbers." You get a bag of components, solder them on a pcb, and hope for the best. I just finished a DIY, JFET phonostage where I sourced virtually all the components, and tested and matched all critical pieces; Also, I was able to selected peripherals like coupling caps. The entire project, from research to completion, took over six months; and I enjoyed the involvement, learned a lot, and ended up with a very nice phonostage. Certainly better than I could have bought for the same money.
I appreciate all the thoughts.
@ wdecho - thanks for the leads, I'll digest the information and may have some follow-up.
@ mcandar - I'll certainly check into the kits that you suggest. My experience with kits has been that it's a little like "Paint-by-numbers." You get a bag of components, solder them on a pcb, and hope for the best. I just finished a DIY, JFET phonostage where I sourced virtually all the components, and tested and matched all critical pieces; Also, I was able to selected peripherals like coupling caps. The entire project, from research to completion, took over six months; and I enjoyed the involvement, learned a lot, and ended up with a very nice phonostage. Certainly better than I could have bought for the same money.
I appreciate all the thoughts.
I totally understand as i much prefer to build my own. I can highly recommend a 4P1L preamp, i built one to drive my F4 amplifier and couldn't be happier with it. Its loosely based on the siberian gen 3 in that its filament biased using Rod Coleman regulators, but i used constant current plate loads and a capacitor coupled output on mine.
Some info here http://www.bartola.co.uk/valves/dht-pre-amplifier/siberian-gen-3-4p1l-pre-amplifier/ and here http://www.diyaudio.com/forums/tubes-valves/190857-4p1l-dht-line-stage.html
I don't see it as that simple. Tubes with lower mu most often have lower Rp which makes it possible to use transformer outputs. Personally I don't want to use coupling capacitors so for me that is important. For you it might not be an issue. Also with low Rp tubes you can use an autoformer for volume control at the output. This might also not be an issue for you.
So from that perspective it doesn't make sense to ME (and possibly only me) to build a preamp with 40dB of gain and attenuate with a potentiometer by 48dB and wreck sound with that filter created there and an output capacitor.
As always, just my opinion and there are many different ways to get happy.
(And it's not about power but gain. And you want a low output impedance.)
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