Class A2 ist a diffrent pair of shoes.. If you work with grid current, there's even more. A little insider tip.
I always drive my tubes so that they feel good and chill, but everyone as they like
SET amp owners thread
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I always drive my tubes so that they feel good and chill, but everyone as they like
It’s not A2…Class A2 ist a diffrent pair of shoes.. If you work with grid current, there's even more. A little insider tip.
I always drive my tubes so that they feel good and chill, but everyone as they like
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I don’t think mains voltage is the issue — I believe the tubes are. All Russian tube designs are problematic. Maybe it’s a matter of manufacturing quality, but we can’t know for sure since they’re not made anywhere else. Lamm, BAT, Tenor, etc.
I do not think that the tube designs are problematic, but mainly that control quality is variable and depends on the distribution networks .Surely some designers overuse their tubes and/or ignore some basic aspects of switch-on / switch-off sequences. Many designs are critical on tubes as they rely on very close matching of some tubes - some Audio Research and Lamm gear included.
I had systematic problems with chinese tubes in the 90's, but russian tubes coming from reliable sources were never a problem in thirty years. However people buying cheap on alternative circuits must remember that rejected operational tubes are not smashed by premium sellers or manufacturers, they just are sold at low price ...
BTW, proper burn-in of tubes, as I learned from Ralph Karsten, will reduce significantly the probability of problems.
Sorry, no its is a series regulator pass tube used in regulated power supplies. But yes, its use in MIG fighters is legendary.
BTW, power tubes can be used as rectifiers - the famous Marantz Project T-1 tube amplfier that I will forever regret having sold
used 845 tubes as rectifiers.
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With Lamm, main voltage is almost always a problem. 6cc33 runs at 175v dc at 310mA, 56watt anode power dissipation (60watt max).therefore the regulation.
In any case, the 6C33 is not a very good tube. Even if you pre-age (bake) it, there is a lot of waste in tubes to achieve the same quiescent current. This is still possible with older ones from the 60s, but with new productions it is a disaster.
Exsample 6c33 (1965)
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The use of the 6C33 in an SET is problematic at best. Since it was designed as a regulator, it has high linearity, which is good, but regulator tubes tend to be low Voltage high current as opposed to higher Voltage and lower current of regular power tubes. The higher current means there is more DC current flowing through the output transformer, which tends to cause a DC magnetic field. That in turn causes distortion since the core is saturated easily by the DC. As I've mentioned a good number of times on this thread, a saw cut has to be made in the core of the output transformer to reduce the DC magnetic field. This results in a dramatic loss of inductance at low frequencies, a problem I've already explained.
With more current, the gap must be wider. You can get around this a bit by making the core larger so its harder to saturate, but you pay a price for that in terms of bandwidth. That is why its common to see 35 Watt rated output transformers for a 300b that can only make about 7 Watts. The thing is, a 6C33 needs bias current in hundreds of milliAmps rather than 10s of milliAmps like a 300b. So building an output transformer for a tube like this is a real challenge; much easier to get similar power levels using an 845 or the like since the current levels (which are what creates a DC magnetic field) are much lower.
You have the additional problem of the socket being inadequate to the task of the filament current of a 6C33. I've seen the power tubes outlast the sockets a number of times and you can't use Teflon sockets for this tube at all. The Russians knew about this problem and recommended socket replacement with the tube; since this was for a military application that service life was 750 hours. The original 6C33s shipped to the US during the early 1990s were shipped with a new socket on this account. The importer, New Sensor of NYC, figured that out after a while and started removing the sockets from the packaging and selling them separately.
The earlier 6C33s made prior to the early 1980s were significantly better as previously indicated. They had a lower plate resistance among other things. They are difficult to find and look nearly identical to the later, inferior, production. How I know all this is Atma-Sphere was the first US manufacturer to use that tube. We were able to get nearly 120 Watts out of a quad of them in our OTLs but had to downgrade that power to 60 Watts as the older version got harder and harder to find. It has a nice robust sound but there's no way to get around the socket reliability problem even with forced air cooling. You just have to expect that the output tube sockets will have to be replaced on a schedule.
With more current, the gap must be wider. You can get around this a bit by making the core larger so its harder to saturate, but you pay a price for that in terms of bandwidth. That is why its common to see 35 Watt rated output transformers for a 300b that can only make about 7 Watts. The thing is, a 6C33 needs bias current in hundreds of milliAmps rather than 10s of milliAmps like a 300b. So building an output transformer for a tube like this is a real challenge; much easier to get similar power levels using an 845 or the like since the current levels (which are what creates a DC magnetic field) are much lower.
You have the additional problem of the socket being inadequate to the task of the filament current of a 6C33. I've seen the power tubes outlast the sockets a number of times and you can't use Teflon sockets for this tube at all. The Russians knew about this problem and recommended socket replacement with the tube; since this was for a military application that service life was 750 hours. The original 6C33s shipped to the US during the early 1990s were shipped with a new socket on this account. The importer, New Sensor of NYC, figured that out after a while and started removing the sockets from the packaging and selling them separately.
The earlier 6C33s made prior to the early 1980s were significantly better as previously indicated. They had a lower plate resistance among other things. They are difficult to find and look nearly identical to the later, inferior, production. How I know all this is Atma-Sphere was the first US manufacturer to use that tube. We were able to get nearly 120 Watts out of a quad of them in our OTLs but had to downgrade that power to 60 Watts as the older version got harder and harder to find. It has a nice robust sound but there's no way to get around the socket reliability problem even with forced air cooling. You just have to expect that the output tube sockets will have to be replaced on a schedule.
Exactly, Ralph, the socket is the Achilles' heel. Always use the good old Russian ones made of ceramic. Normal tubes have a temperature of 200-250 degrees Celsius, but this damned beast easily reaches 350 degrees Celsius at the socket after an hour. It's a good thing the soldering points are well insulated from the ceramic, otherwise it would desolder itself.
Every six months, clean the socket pins thoroughly; a deadly coating accumulates there, leading to serious failures. Soak the pins in warm distilled water, then clean them...for a hopefully long life.
Every six months, clean the socket pins thoroughly; a deadly coating accumulates there, leading to serious failures. Soak the pins in warm distilled water, then clean them...for a hopefully long life.
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I have had good luck with 6C33c tubes, 6N6p, 6N30p, 6N23p etc. Only GM70 doesn’t seem to last that long but my amp drove them at the upper limit to get max power.
Lamm Ml2 uses one to regulate the output tube…another 6c33c! Unique among SETs AFAIK…
I have had pretty good luck then because I have owned four different amps with this tube and only once had a tube failure.
Lamm ML2.2 monoblock power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements To measure one of the Lamm ML2.2 amplifiers (serial no.B10254), I used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It").
Lamm ML2.1 monoblock power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements Following Vladimir Lamm's instructions, I let the ML2.1 run for an hour or so before I checked the output tube's plate voltage and current. While the voltage was correct at 175V DC, the current was a little high at 0.35A. I adjusted it to read exactly 310mA, as...
The output transformers look pretty adequate on these two later versions of the ML2. Note from the 8 ohm tap into 2 ohms it’s still not saturating. This is not high power but shows a good transformer design.
Balanced Audio Technology VK-56SE power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements I measured the Balanced Audio Technology VK-56SE using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). The VK56-SE looks identical to the VK-55SE, which Wes Phillips reviewed in April 2010, and it was instructive to compare its measured...
Lamm ML2.2 monoblock power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements To measure one of the Lamm ML2.2 amplifiers (serial no.B10254), I used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It").www.stereophile.com
Lamm ML2.1 monoblock power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements Following Vladimir Lamm's instructions, I let the ML2.1 run for an hour or so before I checked the output tube's plate voltage and current. While the voltage was correct at 175V DC, the current was a little high at 0.35A. I adjusted it to read exactly 310mA, as...
The output transformers look pretty adequate on these two later versions of the ML2. Note from the 8 ohm tap into 2 ohms it’s still not saturating. This is not high power but shows a good transformer design.
BAT, on the other hand, has quite obvious core saturation even though the amp is a circlotron PP design.Balanced Audio Technology VK-56SE power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements I measured the Balanced Audio Technology VK-56SE using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). The VK56-SE looks identical to the VK-55SE, which Wes Phillips reviewed in April 2010, and it was instructive to compare its measured...
As I understand it, the ML2 transformer is the same size and specification, just a different manufacturer.
Toroids don't make good output transformers as they saturate much more easily than EI core designs. If the tubes had been properly (dynamically) matched its a good bet the saturation problem (if that is really what is being shown) would not have shown up.BAT, on the other hand, has quite obvious core saturation even though the amp is a circlotron PP design.Balanced Audio Technology VK-56SE power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements I measured the Balanced Audio Technology VK-56SE using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). The VK56-SE looks identical to the VK-55SE, which Wes Phillips reviewed in April 2010, and it was instructive to compare its measured...
The advantage of the Circlotron when an output transformer is used is that the primary winding impedance can be 1/4th that of a conventional output transformer design, thus offering wider bandwidth. The downside is none of the Voltage gain of the amplifier occurs in the output section. This is a big ask of the Voltage amplifier; as a result most of the distortion of the amplifier usually occurs in the Voltage amplifier rather than the output section, unless there's a significant imbalance in the output. The BAT runs zero feedback so was not able to compensate for saturation in the core of its output transformers.
(...)BAT, on the other hand, has quite obvious core saturation even though the amp is a circlotron PP design.Balanced Audio Technology VK-56SE power amplifier Measurements | Stereophile.com
Sidebar 3: Measurements I measured the Balanced Audio Technology VK-56SE using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). The VK56-SE looks identical to the VK-55SE, which Wes Phillips reviewed in April 2010, and it was instructive to compare its measured...
IMO it should have been called a distortion generator, not an amplifier. I can't understand how a core starts saturating at 1kHz at 1W!
Nice clean wiring. Did you do this?
How do you clean inside pin sockets. I can get in a KT pin socket. Its the small driver and signal tubes that are the issue. I have a thin cotton pipe cleaner for the larger holes.
I have tried dozens of amplifiers, solid state and tube, with my Quad 2905’s. Nothing is as sublime sounding as my JJ 322 parallel SET. It uses two pairs of 300B’s per channel to produce about 20 watts, which feels ample for my listening tastes. It’s a behemoth weighing almost 100 pounds. The literature on it describes the output transformers as “C-cores”.
I believe the Lamm ML2 is one of the best sounding SET amps ever made. I chose not to get a pair after struggling with the 63CC in my Lamm ML1.1 push pull. Lamm said that he’d have to throw away 75% of them to get tubes to his SPEC.
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