Hi Guys,
I want to build a tube preamp for my system.
I have seen many many tube preamps on the internet but I dont know which one to build as I dont know which ones sound good.
My main concern with building a preamp is clarity and jusy plain musical enjoyment.
I have a bunch of 6922 tubes but from what I have read, they are not the best preamp tubes.
So can you guys suggest an excellent sounding preamp?
BTW compexity isnt an issue, I alredy have experience with tubes.
Thanks, looking forward to the responses.
Lawrence
I want to build a tube preamp for my system.
I have seen many many tube preamps on the internet but I dont know which one to build as I dont know which ones sound good.
My main concern with building a preamp is clarity and jusy plain musical enjoyment.
I have a bunch of 6922 tubes but from what I have read, they are not the best preamp tubes.
So can you guys suggest an excellent sounding preamp?
BTW compexity isnt an issue, I alredy have experience with tubes.
Thanks, looking forward to the responses.
Lawrence
I don't know if it's the best but I think its very good and it uses 6922's so ....
http://www.vacuumstate.com/images/FVP5A.gif
http://www.vacuumstate.com/images/FVP5A.gif
Here is an interesting schematic I came across that I was wondering about as well and wouldn't mind some feedback as to what others might think of it.
http://www.geocities.com/rjm003.geo/rjmaudio/diy_ls.html
Stan
http://www.geocities.com/rjm003.geo/rjmaudio/diy_ls.html
Stan
Hi,
Regarding the C-J style line stage, I feel this is overkill, big time.
From a manufacturer's POV this could be justified but a DIY-er needing only the right tube for the job, there's just no way.
The good news is that the same site also hosts a decent phonostage that, coupled to a tube rectified PS as shown, has every chance of being excellent.
If it needs to be MC capable , you can tack on my MC Hammer Headamp as described somewhere here on the forum.
The requirements for the linestage are low noise, low Zout and just a couple of dB of gain (to make everyone happy).
The rest is mostly a matter of good circuit layout, component choice and of course a decent volumecontrol.
Cheers,😉
Regarding the C-J style line stage, I feel this is overkill, big time.
From a manufacturer's POV this could be justified but a DIY-er needing only the right tube for the job, there's just no way.
The good news is that the same site also hosts a decent phonostage that, coupled to a tube rectified PS as shown, has every chance of being excellent.
If it needs to be MC capable , you can tack on my MC Hammer Headamp as described somewhere here on the forum.
The requirements for the linestage are low noise, low Zout and just a couple of dB of gain (to make everyone happy).
The rest is mostly a matter of good circuit layout, component choice and of course a decent volumecontrol.
Cheers,😉
Thanks for the replies guys, keep them comming!!!
Hey fdegrove from your posts in other theads it seems as if you have a lot of experience in the tube world. So could you tell me which is your favourite preamp?
Others are welcome to share their experiences.
BTW I dont need a phono section I only plan to use my CD player.
Lawrence
Hey fdegrove from your posts in other theads it seems as if you have a lot of experience in the tube world. So could you tell me which is your favourite preamp?
Others are welcome to share their experiences.
BTW I dont need a phono section I only plan to use my CD player.
Lawrence
Frank has posted his own design- a quick search should turn it up.
If you only need a line amp, a very simple design will do. A 6922 will work well, as will tubes in the 6SN7 family, 6N1P... The multiple-parallel 6922, there's really no sense behind that sort of design for this application, IMO.
If you only need a line amp, a very simple design will do. A 6922 will work well, as will tubes in the 6SN7 family, 6N1P... The multiple-parallel 6922, there's really no sense behind that sort of design for this application, IMO.
I can second Andrewbee's recommendation for the Vacuumstate FVP5 and the even better RTP3C, if you need phono. Should you only need line, then there's Frank's design or my little one; doesn't get much simpler than this.lawbadman said:
FWIW, get over the idea of there being a 'best', it'll save a lot of tail chasing and sufferring searching for a mythical nirvana. You're either going to have to build a ton of circuits and decide for yourself, or just build something and be satisfied. Of all the pre's I've mentioned, I've actually built and use them all (FVP5A and RTP3C phono stages and the 12B4A line).
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Dave Davenport"s differential parafeed linestage is very good. I'm currently running a 5687 variant, using cheap power toroids for phase splitter and OPT, and this cheap little thing rocks. I'm curious to know what improvements would be had by bringing in Lundahl iron, etc.
just curious...
what do you guys do about the inverting output on your single stage preamps? hook the speakers up out of phase? or is the amp also inverting?
just curious...
jc
what do you guys do about the inverting output on your single stage preamps? hook the speakers up out of phase? or is the amp also inverting?
just curious...
jc
Hi,
Actually I suspect most people aren't even aware of the potential problem but inverting the + and - leads at the speaker cable end of the business is one solution. (Although not quite the same to my ears, just don't ask me why.....)
Quite often people claim they can't detect any difference either way, so they can't be bothered.
Others claim that half of their records are recorded with the wrong polarity hence can't be bothered either.
Personally I try to design preamps that respect polarity.
Back in the days when you designed phonostages that was relatively easy as you often ended up using a cascade of two inverting stages.
Either way, it would be advisable to check absolute polarity of the entire system. Correct for it, either at the input or the output.
Good thing you raised the point as most designers neglect to mention this nowadays........
Cheers,😉
Actually I suspect most people aren't even aware of the potential problem but inverting the + and - leads at the speaker cable end of the business is one solution. (Although not quite the same to my ears, just don't ask me why.....)
Quite often people claim they can't detect any difference either way, so they can't be bothered.
Others claim that half of their records are recorded with the wrong polarity hence can't be bothered either.
Personally I try to design preamps that respect polarity.
Back in the days when you designed phonostages that was relatively easy as you often ended up using a cascade of two inverting stages.
Either way, it would be advisable to check absolute polarity of the entire system. Correct for it, either at the input or the output.
Good thing you raised the point as most designers neglect to mention this nowadays........
Cheers,😉
Hi,
Maybe I'm overlooking something but single stage non-inverting line stages seem to have their drawbacks too.
The grounded grid stage, for instance, has low Zin (no prob) but invariably high Zout (not so good)...
Since I have the cathodyne phase splitter in the back of my head I had the following idea:
Why not make a classic anode follower, direct couple that one (if you like) into a cathodyne splitter, add a toggle switch at the output ends so the user can choose between either output.
Heck, if you don't care about that you can even use it as a balanced output to drive a balanced input at the amp's.
All it takes is two triodes and you're done.
The ultimate purist can even take the signal (out of phase) off the plate of the first triode if the higher Zout is no object.....
Just thinking out loud though....
Cheers, 😉
Maybe I'm overlooking something but single stage non-inverting line stages seem to have their drawbacks too.
The grounded grid stage, for instance, has low Zin (no prob) but invariably high Zout (not so good)...
Since I have the cathodyne phase splitter in the back of my head I had the following idea:
Why not make a classic anode follower, direct couple that one (if you like) into a cathodyne splitter, add a toggle switch at the output ends so the user can choose between either output.
Heck, if you don't care about that you can even use it as a balanced output to drive a balanced input at the amp's.
All it takes is two triodes and you're done.
The ultimate purist can even take the signal (out of phase) off the plate of the first triode if the higher Zout is no object.....
Just thinking out loud though....
Cheers, 😉
That's one way to do it. Another way is to cascade two inverting stages, add a buffer, then use whatever feedback is necessary to get the gain where you want it. Yet another way is the one I use, which is to run the gain tube grounded grid, then buffer the output.
Lawrence,
If you are only planning to use CD (I assume you have a decent player in your setup) why building a preamp at all? I would guess the output level of most CD players is plenty to drive an amp directly?
DocLorren
If you are only planning to use CD (I assume you have a decent player in your setup) why building a preamp at all? I would guess the output level of most CD players is plenty to drive an amp directly?
DocLorren
There are some interesting designs out there but try building a Rosenbilt Grounded Grid before you waste time on any of the others. I just built two of them and the results were astounding. Two variables in it are the output coupling cap and the feedback resistor. Use 5uf and 150K instead of what is called for. Also get 6189W's(Sylvania or G.E.) and you won't have the microphonic problem that most 12AU7's suffer from. Takes about a week to fully break in...... You will not be disappointed!
Mark
Mark
Hello
Can I use the Grid to drive some of the Zen variants for Nelson Pass? Zen, SOZ, SOX etc...
Can I use the Grid to drive some of the Zen variants for Nelson Pass? Zen, SOZ, SOX etc...
Yes, it drives as low as 300 ohms I believe. I'm driving a pair of Aleph 2's with mine. Total cost to build mine was around $100.00 U.S. even with the NOS 6189W's. I literally threw them together in about a day and a halfs time! I still have to make the wooden base.... just picked up some nice quater sawn oak for it. The attenuator is a nice old Daven "T" type that I converted to 50K ladder type.
Mark
Mark
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Power Supply end of things..... All wiring is silver plated OFC copper that is teflon insulated. No hum, no noise, no hiss! The star ground point is between the two output caps. It doesn't sound like typical tube or solid state circuit... very different and unique character all its own.
Mark
Mark
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