I am a total newbie to tubes and would like to make a tube preamp. I was planning to make a headphone amp first, but due to output transformers availability (or rather lack of), its probably going to be delayed.
I dont need gain as I mainly use cd players and sound cards. No vinyl yet. My amp right now is a topping tp20 and yammy 663. I will probably replace the tp20 with myref revc in near future, and someday maybe a tube amp. This is going to be mainly for my desktop system. I already have a pass B1 for my other system.
I have the following tubes with me. If there is a very good design without these, i could try to get some other different tubes, but would prefer if I could manage with some of these.
ECC81, ECC82, ECC83, ECC88, 12AU7A, 5751, ECL86, PCL86, ECL82, PCL805. I have some more, will list those later.
For rectifier, I could get my hands on some of these - gz34, 5au4, ez81, PY88, 5U4, 5y3
For power transformers, it will be difficult to get a ready made trafo, I could get one custom wound. I could easily get my hands on an isolation trafo (230v) or a step down to US voltage trafo (230-110v). For heater, i can easily get a separate trafo of integer voltages 5,6,7,8... volts. I also saw one company making 6.3v upto 3A, so might try that. Pre built ones will be EI, but for custom wounds, i can go with any of EI, torroidal, R-cores. Any special care needed to use multiple power transformers? Which ones are recommended.
I would also prefer a simple design. I have a problem doing layout of complex p2p circuits, these very quickly become a mess and get out of hand. I need more experience.
Please suggest some design that can fit these needs. I would also need a power supply design to go with these.
I dont need gain as I mainly use cd players and sound cards. No vinyl yet. My amp right now is a topping tp20 and yammy 663. I will probably replace the tp20 with myref revc in near future, and someday maybe a tube amp. This is going to be mainly for my desktop system. I already have a pass B1 for my other system.
I have the following tubes with me. If there is a very good design without these, i could try to get some other different tubes, but would prefer if I could manage with some of these.
ECC81, ECC82, ECC83, ECC88, 12AU7A, 5751, ECL86, PCL86, ECL82, PCL805. I have some more, will list those later.
For rectifier, I could get my hands on some of these - gz34, 5au4, ez81, PY88, 5U4, 5y3
For power transformers, it will be difficult to get a ready made trafo, I could get one custom wound. I could easily get my hands on an isolation trafo (230v) or a step down to US voltage trafo (230-110v). For heater, i can easily get a separate trafo of integer voltages 5,6,7,8... volts. I also saw one company making 6.3v upto 3A, so might try that. Pre built ones will be EI, but for custom wounds, i can go with any of EI, torroidal, R-cores. Any special care needed to use multiple power transformers? Which ones are recommended.
I would also prefer a simple design. I have a problem doing layout of complex p2p circuits, these very quickly become a mess and get out of hand. I need more experience.
Please suggest some design that can fit these needs. I would also need a power supply design to go with these.
As you stated, you don't need gain. A "unity" gain buffer will do the job. In tubed circuitry, what's needed is a cathode follower in each channel. High transconductance (gm) makes for good cathode followers.
Among the types you listed, the 6DJ8/ECC88 has the highest gm. That type operates with approx. 90 V. on its plate. "Best" results with cathode followers are obtained with a bipolar PSU and constant current sink (CCS) loading. As long as a DC offset is not present at the I/P, the only capacitor in the signal path is at the circuit's O/P. Forget about vacuum rectification. A power trafo with a 125-0-125 rectifier secondary and 4X 600 PIV Schottky diodes takes care of the bipolar PSU. Add some electrolytic caps. and a couple of chokes and you're in business.
BTW, the 6GW8/ECL86 is scarce. You can sell them to fund part of the cost of this 1st project.
Among the types you listed, the 6DJ8/ECC88 has the highest gm. That type operates with approx. 90 V. on its plate. "Best" results with cathode followers are obtained with a bipolar PSU and constant current sink (CCS) loading. As long as a DC offset is not present at the I/P, the only capacitor in the signal path is at the circuit's O/P. Forget about vacuum rectification. A power trafo with a 125-0-125 rectifier secondary and 4X 600 PIV Schottky diodes takes care of the bipolar PSU. Add some electrolytic caps. and a couple of chokes and you're in business.
BTW, the 6GW8/ECL86 is scarce. You can sell them to fund part of the cost of this 1st project.
Hi, I made an amplifier for mobile phones
on 6F12P (Soviet lamps) triode and pentode,
triode with a gain of 100 (0.25 X100)
pentode as a cathode follower, the output
any power transformers (220) rated at 10 watts, with
output voltage of about 10 volts.
The power transformer capacity of at least 20 watts,
two windings, 6.3 (1.2 A) and 250 (0.05 A), the rectifier
semiconductor, power supply, a separate unit,
no background at all, superb sound (CBS-15)
look for the scheme, have to drive somewhere.
Success, aeandm
on 6F12P (Soviet lamps) triode and pentode,
triode with a gain of 100 (0.25 X100)
pentode as a cathode follower, the output
any power transformers (220) rated at 10 watts, with
output voltage of about 10 volts.
The power transformer capacity of at least 20 watts,
two windings, 6.3 (1.2 A) and 250 (0.05 A), the rectifier
semiconductor, power supply, a separate unit,
no background at all, superb sound (CBS-15)
look for the scheme, have to drive somewhere.
Success, aeandm
This is a general question and not aimed at the OP or anyone else. Why do people build preamps?
I have a tube amp that can be driven from my cd player, tape deck, TV, etc .
I understand the utilitarian nature of a selector for this purpose. If the tube amp input impedance were low I could see a buffer might be necessary if the sources could not drive the amp. And possibly buffers might be useful to reduce noise pickup from the selector signal inputs (although I'm not sure on even this).
Unless gain is needed, why build a preamp at all (either tube or SS)?
I have a tube amp that can be driven from my cd player, tape deck, TV, etc .
I understand the utilitarian nature of a selector for this purpose. If the tube amp input impedance were low I could see a buffer might be necessary if the sources could not drive the amp. And possibly buffers might be useful to reduce noise pickup from the selector signal inputs (although I'm not sure on even this).
Unless gain is needed, why build a preamp at all (either tube or SS)?
A preamp is rarely needed these days, and when it is, generally unity gain is sufficient. I use a buffer (a real buffer, not a badly designed gain stage) to get me high common-mode rejection and the ability to drive multiple inputs from multiple sources that a simple potentiometer and switch won't allow.
I have tried it a couple of times , in the past
and have to say, a very simple and cheap tube pre/buffer could do wonders, or almost
to do the same with SS pre in those days would have been almost impossible, or very expencive to buy
but today ? I'm not sure
how about 'Juma's sit trioda' ?
that said, a tube pre can also screw up things
you need to make sure your load impedances are up to it, meaning high enough
I generally use an Alps stereo 100K pot on the input of my amps. With min at 7pm and max at 5pm, I rarely go above a noon setting when driven from my CD player or the FM stereo receiver.
Since I have yet to build a RIAA corrected record preamp, I am currently playing through the record preamp in the FM receiver.
If I ever finish setting up a HT system I suppose things may change.
Since I have yet to build a RIAA corrected record preamp, I am currently playing through the record preamp in the FM receiver.
If I ever finish setting up a HT system I suppose things may change.
yes, you can do that with tube based poweramp
btw, a tube pre have always been known to have rolled off top, and sluggish lows, compared to SS preamps
and a SS design might be perceived as having slightly finer 'textures'
but the tighter bottom could at the same time be perceived as rahter thin, or boring
and regarding lack of 'substance', that could be where a tube design shines
everything could depend on your other electronics, and your speakers especially
ofcourse you can always design it all to match each other
and yeah, I do know you can design tubegear to sound no different from solid state
I have even heard of tube amps that sounded 'too much of bad solid state design'
seems like almost anything is possible
if you want to build a tube pre for fun, yeah, sure, why not
if your goal is 'better sound', it could be a different and more tricky affair
on the other hand, you still might have to build one to know for yourself
talk and wise words wont do it
so what's it gonna be ?
btw, a tube pre have always been known to have rolled off top, and sluggish lows, compared to SS preamps
and a SS design might be perceived as having slightly finer 'textures'
but the tighter bottom could at the same time be perceived as rahter thin, or boring
and regarding lack of 'substance', that could be where a tube design shines
everything could depend on your other electronics, and your speakers especially
ofcourse you can always design it all to match each other
and yeah, I do know you can design tubegear to sound no different from solid state
I have even heard of tube amps that sounded 'too much of bad solid state design'
seems like almost anything is possible
if you want to build a tube pre for fun, yeah, sure, why not
if your goal is 'better sound', it could be a different and more tricky affair
on the other hand, you still might have to build one to know for yourself
talk and wise words wont do it
so what's it gonna be ?
Yes, but buffered, like I said. There's also a transformer for CMR. It is transparent, not an effects box. I need the buffer because of impedances and cable lengths- a 10k passive is usually fine for 90% of the world.
if its actively buffered its not passive, is it ?
but yeah, passive can be very transparent
though, some people might think something is missing
could depend on a lot of other factors
personally, I also prefer transparancy, surely
but I also build my own speakers to match it
and since the OP is asking about it this way, my guess is its because he is missing 'something', whatever it is ? speaker BSC missing maybe, like it often happened in the old days ?
but yeah, passive can be very transparent
though, some people might think something is missing
could depend on a lot of other factors
personally, I also prefer transparancy, surely
but I also build my own speakers to match it
and since the OP is asking about it this way, my guess is its because he is missing 'something', whatever it is ? speaker BSC missing maybe, like it often happened in the old days ?
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