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Is it possible to have fully balanced from input to output amplification with only 1 tube?

shion_ca

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Was looking at a design for a class D amp with a tube input stage. I only see one tube for the mono block. My question is, can you have a fully balanced design with one tube in it... wouldn't you need one for each inverted signal? Please forgive if its a dumb question.
 
Why would a class D amp use a tube? Some sort of pre-amp fantasy?
 
Yes. The VALVE has to be balanced too. Both top and bottom of the tube need to be very close when tested. I have a simular preamp section
on my Carys (a single balanced or matched valve.) There are even 3 matched sections in small valves.
Examples of dual-triode 12ax7, 12au7, 12at7, 12av7, etc.

12AX7​


Wikipedia
https://en.wikipedia.org › wiki › 12AX7





12AX7 (also known as ECC83) is a miniature dual-triode vacuum tube with high voltage gain. Developed around 1946 by RCA engineers in Camden, New Jersey, ...

6au7 is a 6 volt vs 12 volt. dual-triode.

There are MANY cases where only one side of the valve was used and they are resold. It's fine if your wired for the unused section. Instruments used to be
wired that way. But then again a balanced 12at7 used to cost 3.00-5 dollars, the same with any of the 12XX7. A pair of matched 12ax7 (s) RCA or EC83 can cost
75-400.00 dollars. Tellies, Valvo, Mazda, RCA, GE, Mullard and a few more.
 
Some sort of pre-amp fantasy?
Fantasy? They are simply using a valve vs solid state in the circuit. Strange how they STILL use valves in Russian jets for a reason. They are NOT
affected by EMPs. The military grade valves are tough as hell and VERY accurate. I believe they are used in portions of their different radars.
If they are good enough for that, they will be just fine is a silly stereo.

Buffer board on your class D? Fun idea if nothing else
 
Fantasy? They are simply using a valve vs solid state in the circuit. Strange how they STILL use valves in Russian jets for a reason. They are NOT
affected by EMPs. The military grade valves are tough as hell and VERY accurate. I believe they are used in portions of their different radars.
If they are good enough for that, they will be just fine is a silly stereo.

Buffer board on your class D? Fun idea if nothing else
I don't worry about EMPs with my audio gear, tho :)
 
I don't worry about EMPs with my audio gear, tho :)
Well when the nukes all go off and your in your basement with the gas generator... your gonna be sorry if you're the only person left alive and your stereo doesn't work anymore :)
 
your gonna be sorry if you're the only person left alive and your stereo doesn't work anymore
Don't worry I have over 50 pieces of valve gear, primary Mcintosh and 10-12 pieces of Cary Valve gear. V12Rs are one of my all time favorite
valve amps. I'm pretty impressed with the SLP-05 too and I NEVER thought I would like any preamp more than the Early Mcintosh preamps.
Mcintosh C20s are one of the most colorful and have more tools via Bass contour, Tone Controls, Variable loudness, and several options on
low and high filters, not mention with just a little bit of work offer .05 distortion vs the factory of .5 THD. Onboard dual turntable preamps
for MM, MI and MC carts. C11, C22 90% of the parts interchange and they have almost all of the same features as a C20. The two issue is
no remote and like ALL early Preamps crosstalk. You can mitigate most of that with RCA stoppers.

As for the basement, it's not connected to the fallout shelter. AND EMPs don't just come from bombs. :cool: They used them to stop SS ignitions
on anything with any of the newer ignition system (70s forward, close). Not that hard to build actually. Even newer diesels have SS injectors and
COPS have access to EMP Pulse guns. Few cars/pickups or semi are shielded. The problem is many steering and braking systems now requires a
hydraulic pump to work.
Kill the engine you get to pull over, period. Loose a serpentine belt has the same effect. Some of the manufactures are going to electric
hydraulic pumps and electric turbos, BUT they are subject to EMP pulse guns also. Catch 22.

Enjoy your new amps and remember that single tube has to be a good full range valve and test as matched top to bottom. Not knowing the circuit,
a simple roll depending on the valve can make a LOT of difference.

6922, AT series, and the 6 volt 6Nxxx all have many alternatives. Tellies, Mullard's and SOME RCA are hard to beat.
Most new stuff is JJ, not my favorite, but very reliable considering. My Herron V2 TT preamp came with them, very reliable.
12 years old, never a single problem. It's actually the best TT pre I've ever owned for the money.

Regards
 
Was looking at a design for a class D amp with a tube input stage. I only see one tube for the mono block. My question is, can you have a fully balanced design with one tube in it... wouldn't you need one for each inverted signal? Please forgive if its a dumb question.
A dual triode tube could provide that, but I question the use of a tube in a class D application. Make the whole amp tube!
 
Don't worry I have over 50 pieces of valve gear, primary Mcintosh and 10-12 pieces of Cary Valve gear. V12Rs are one of my all time favorite
valve amps. I'm pretty impressed with the SLP-05 too and I NEVER thought I would like any preamp more than the Early Mcintosh preamps.
Mcintosh C20s are one of the most colorful and have more tools via Bass contour, Tone Controls, Variable loudness, and several options on
low and high filters, not mention with just a little bit of work offer .05 distortion vs the factory of .5 THD. Onboard dual turntable preamps
for MM, MI and MC carts. C11, C22 90% of the parts interchange and they have almost all of the same features as a C20. The two issue is
no remote and like ALL early Preamps crosstalk. You can mitigate most of that with RCA stoppers.

As for the basement, it's not connected to the fallout shelter. AND EMPs don't just come from bombs. :cool: They used them to stop SS ignitions
on anything with any of the newer ignition system (70s forward, close). Not that hard to build actually. Even newer diesels have SS injectors and
COPS have access to EMP Pulse guns. Few cars/pickups or semi are shielded. The problem is many steering and braking systems now requires a
hydraulic pump to work.
Kill the engine you get to pull over, period. Loose a serpentine belt has the same effect. Some of the manufactures are going to electric
hydraulic pumps and electric turbos, BUT they are subject to EMP pulse guns also. Catch 22.

Enjoy your new amps and remember that single tube has to be a good full range valve and test as matched top to bottom. Not knowing the circuit,
a simple roll depending on the valve can make a LOT of difference.

6922, AT series, and the 6 volt 6Nxxx all have many alternatives. Tellies, Mullard's and SOME RCA are hard to beat.
Most new stuff is JJ, not my favorite, but very reliable considering. My Herron V2 TT preamp came with them, very reliable.
12 years old, never a single problem. It's actually the best TT pre I've ever owned for the money.

Regards
Do you have one of the more recent slp-05’s? How would it pair with a purifi 9040? I was thinking about exactly that combo. Would very much appreciate your thoughts.
 
In the tube days this was commonly done with transformers. Recording and broadcast consoles had modular balanced in and balanced out tube preamps. Jensen continues to make transformers for audio.
 
In the tube days this was commonly done with transformers.
I was just typing the same thing! You beat me by a few seconds!
 
Don't worry I have over 50 pieces of valve gear, primary Mcintosh and 10-12 pieces of Cary Valve gear. V12Rs are one of my all time favorite
valve amps. I'm pretty impressed with the SLP-05 too and I NEVER thought I would like any preamp more than the Early Mcintosh preamps.
Mcintosh C20s are one of the most colorful and have more tools via Bass contour, Tone Controls, Variable loudness, and several options on
low and high filters, not mention with just a little bit of work offer .05 distortion vs the factory of .5 THD. Onboard dual turntable preamps
for MM, MI and MC carts. C11, C22 90% of the parts interchange and they have almost all of the same features as a C20. The two issue is
no remote and like ALL early Preamps crosstalk. You can mitigate most of that with RCA stoppers.

As for the basement, it's not connected to the fallout shelter. AND EMPs don't just come from bombs. :cool: They used them to stop SS ignitions
on anything with any of the newer ignition system (70s forward, close). Not that hard to build actually. Even newer diesels have SS injectors and
COPS have access to EMP Pulse guns. Few cars/pickups or semi are shielded. The problem is many steering and braking systems now requires a
hydraulic pump to work.
Kill the engine you get to pull over, period. Loose a serpentine belt has the same effect. Some of the manufactures are going to electric
hydraulic pumps and electric turbos, BUT they are subject to EMP pulse guns also. Catch 22.

Enjoy your new amps and remember that single tube has to be a good full range valve and test as matched top to bottom. Not knowing the circuit,
a simple roll depending on the valve can make a LOT of difference.

6922, AT series, and the 6 volt 6Nxxx all have many alternatives. Tellies, Mullard's and SOME RCA are hard to beat.
Most new stuff is JJ, not my favorite, but very reliable considering. My Herron V2 TT preamp came with them, very reliable.
12 years old, never a single problem. It's actually the best TT pre I've ever owned for the money.

Regards
Oh, the slp-05 has 14 db gain. That’s a bit much for my balanced setup. Shame they don’t have the typical 4db low gain option by switch. Any issues with the gain and integrating that into your system?
 
A dual triode tube could provide that, but I question the use of a tube in a class D application. Make the whole amp tube!
Dude. I'd be all over an all tube Class A amplifier! ;)

1721952100329.jpeg


That said, I am thinking about the notion of a balanced vacuum tube buffer circuit and whether one could get away with one dual triode.
Unbalanced, sure, no sweat.
Balanced? Can't wrap my head around it (which says more about my level of expertise than the challenge itself). I am just too much of an unbalanced* kind of guy.

1721952541072.jpeg

ECC81 = 12AT7, a twin triode broadly similar to the ECC83/12AX7 but with lower amplification factor.

_________________
* On second thought, Let's say single-ended instead of unbalanced. Sounds less dangerous. :)
 
Fantasy? They are simply using a valve vs solid state in the circuit. Strange how they STILL use valves in Russian jets for a reason. They are NOT
affected by EMPs. The military grade valves are tough as hell and VERY accurate. I believe they are used in portions of their different radars.
If they are good enough for that, they will be just fine is a silly stereo.

Buffer board on your class D? Fun idea if nothing else
If you are talking about the mighty 6C33C russian tube that was used in the MiGs, let me tell you something about them.
You can not find two that match well! they are all over the place when you measure them, they age differently too. They are power tubes, and not used as a buffer.
 
Dude. I'd be all over an all tube Class A amplifier! ;)

View attachment 383061

That said, I am thinking about the notion of a balanced vacuum tube buffer circuit and whether one could get away with one dual triode.
Unbalanced, sure, no sweat.
Balanced? Can't wrap my head around it (which says more about my level of expertise than the challenge itself). I am just too much of an unbalanced* kind of guy.

View attachment 383063
ECC81 = 12AT7, a twin triode broadly similar to the ECC83/12AX7 but with lower amplification factor.

_________________
* On second thought, Let's say single-ended instead of unbalanced. Sounds less dangerous. :)
Screenshot 2024-07-26 030953.jpg
 
Do you have one of the more recent slp-05’s? How would it pair with a purifi 9040? I was thinking about exactly that combo. Would very much appreciate your thoughts.
No actually it's older and never been upgraded or had any mods. I purchased copper/tinned caps, Mylars, and Stealth. LOL I've yet to install them.
I did replace the stock rectifier valve with a Mullard, and purchased a really nice sounding set of Sylvania NOS vs the JJs they came with.
It boils down to me getting of my lazy duff and doing Hexfreds, caps, and a couple of other changes. I just HATE waiting for the Mylars to break-in.
I've installed them at least 1/2 dozen times in other equipment and it take a while for them to form and settle down. The copper/tinned are a 25
hours vs Mylar taking 200-300 hours. I've done a few CJ with mylars. Excellent upgrade for the money 25.00 per cap (close) but some weird shit until
they form properly. I have them in ALL my passive speaker XOs. That was an experience, I hope to never go through again.
Oh, the slp-05 has 14 db gain. That’s a bit much for my balanced setup. Shame they don’t have the typical 4db low gain option by switch. Any issues with the gain and integrating that into your system?
There is a change that Cary does. It bypassed a volume circuit (or what ever the heck it is) and they add some very small caps. On the remaining circuit. They could be
a Bypass (frequency collection caps as Marantz used to call them). It reduces the gain. I personally never had a problem turning DOWN the gain on the two and the
Main volume control is hooked to the remote any way. Even with the L/R gain turned up considerably it still remains BLACK/QUIET as far as floor noise. I like Cary
but to tell the honest truth, my C20 runs circles around the SLP-05. So does a C11 or C22. I love the tone control. I hate not having a remote and they have crosstalk
issues. BUT there are all kinds of ways around that. Simply turning off other connected sources works pretty well.

I'm not much of a LSP preamp fan. I like good tone control with a switch to bypass if I want to. Depended how screwed up the source material was to begin with. Some LP and even CD are fine, but without TC you can't listen to them. Some of these modern recording are WAY to bass heavy. Tami Nielson is a perfect example. There's a few great albums, but without tone control in my set up you would have the cops at the door because of the neighbors windows rattling.

The MAIN reason I like the SLP-05 is a balanced circuit that really complements the V12Rs/Nord combo I use. C2500 Mcintosh is another great modern preamp
with all the whistles and bells on the remote. I can't get MY C2500 back from the wife, she loves it. If you ever use one you would know why. Completely
transparent and balanced with dual TT preamps for MM, MI and MC carts. The DAC is dated but to tell the truth I can't tell the difference in most DACS anyway.
I have a Krell HT5.1 that's 25+ years old. It still sounds wonderful to me for a LSP with bass management/volume control on the remote.

I'm looking at a C2600 or 2700 too. JUST for me, the wife is pretty scrappy, I'd rather deal with the next door neighbors Pitbull to tell the truth.

I'm going to be clearing my inventory, the old Doctor gave me an expiration date if thing go good, but told me to be prepared just in case.
The concrete dust finally caught up, LOL of all things F&^%ing DUST.

The SLP-05 and V12Rs are pretty impressive to LOOK at in Jaguar Red all lit up, 45+ valves and quiet as a mouse. A bit of WORK to maintain that low floor
noise, BUT heck who cares, I'm retired and we have to heat the house in the winter anyway. Why not use valves. Better than playing Bingo at least.

Time to feed the chickens and work on a new set of speakers, I just got the hard wood for the baffle. Tinker time!

Regards and "Enjoy the Toy" as I always say.
 
They are power tubes, and not used as a buffer.
No they a military grade small valves. Solvex, and few others make them. No different than RCA, GE Mullard (M) valves.
El was another that made industrial/military grade. I used to buy in lot of 200 and at least 50% could be matched top to
bottom and valve to valve. I could get 50 pairs pretty easy. 6922, 12at7, 12ax7, 12au7s. Different numbers but the same
dual-elements and the same pinout. Like I said the new JJs are pretty good and GL, Mullard (new release) and Telefunken (NR).
RCAs you need to be very careful with that valve. There is a lot of junk floating around being sold.
There just aren't that many GOOD BP/RCA 12AT7s left. I have 4 good pairs. They are a great valve. As good as or better
than , Tellies or Mullard. Mcintosh MC240/RCA are a match made in heaven if you really like the valve sound.

Nothing compares in my 50 years of listening to a C20/MC240. Tellies in the C20 and RCAs in the MC240. I use Infinity RS4Bs
with that combo. Freaky good. MC225 is a little under powered for GREAT bass but they are close with RCAs and work the PS.
Something about early Mcintosh, hard to beat. Stones, Beach Boys, Beatles, and most of the old Motown stuff. James Brown.

The problem was they sold NOS valves that weren't NOS from scalpers that tried to pull a fast one. They would buy valves
that only 1/2 the valve was used and pulled at 50% or less. The problem was the other half of the valve at 110% and never used.

BTW the Russians and the WHOLE eastern block was a bunch of shady characters, that I delt with.
I KNOW they paid less than a penny a piece for those crap valves I'm referring to. It took me 5 years
to find a bunch I barely trusted in Croatia, or Bosnia.

Regards
 
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