I Love BIG, FAT, HOT, FIREY Russian -- T---- (tubes)

[richieb]

My Almarro 318b arrived and is breaking in as I type. The 6h33c-b is a tremendous tube for high power SE applications, 18 watts is considerable power in single ended circles. There is none of the pesky SE artifacts with this amp; gobs of deep articulate bass, extended highs, rich and toneful midrange, masterful soundstage, the damn thing just sounds so right through the KHorns. Checking bias every couple of hours as they break in, hate for a 6h to melt down with a China Syndrome in eastern KS. Yeah they operate on the flaming side of hot but on a top shelf rack downstairs heat is of no concern and the sound is worth every centigrade, around 275-300. I really believe my rig has come to where further improvements would be marginal. I've said it times before but the room, KHorns/LS and electronics are providing great sound and enjoyment. I'll do my best to download pics tomorrow.

[mxr dad]

Interesting title and had no idea what to expect. I was thinking mail brides! LOL. Funny what 18 watts can do. The first time I heard tubes was a 5 watt kit and not sure of the name but I was the typical non believer quietly thinking to myself, WTH is 5 watts gonna do? HUUMMFF. Well, I am a believer now! My LS came alive with those little 5 watts, if we were even using all 5? Dunno. Nice tubes man.

[LarryC]

The 6h33c-b is a tremendous tube for high power SE applications, 18 watts is considerable power in single ended circles.

Is it a 6h33c, or a 6C33b?  My Joule Electra monoblocs use the 6c's.

 

Yes, very big and very, but not extremely, hot tubes.  See my avatar -- each monobloc has 6, and is rated at 100 w. per. 

 

You're right to check the bias frequently, at least until you're sure they are stable.  One of mine apparently ran away and melted part of the acrylic top plate before I discovered it.

 

One problem is finding solid tube sockets for the 6c33b that don't let the tubes rock out of place if you jiggle them.  This can cause poor socket connections, which might have been my problem.  I think I'll contact Almarro (and BAT) to see if they have solved that problem and if I can get replacement sockets.  Big job, at 12 for the two amps!

 

Aside from all that, yes, excellent tubes, great clarity and linearity.  Great for OTL duty.

Edited April 14, 2015 by LarryC

[OO1]

 

The 6h33c-b is a tremendous tube for high power SE applications, 18 watts is considerable power in single ended circles.

Is it a 6h33c, or a 6C33b?  My Joule Electra monoblocs use the 6c's.

 

Yes, very big and very, but not extremely, hot tubes.  See my avatar -- each monobloc has 6, and is rated at 100 w. per. 

 

You're right to check the bias frequently, at least until you're sure they are stable.  One of mine apparently ran away and melted part of the acrylic top plate before I discovered it.

 

One problem is finding solid tube sockets for the 6c33b that don't let the tubes rock out of place if you jiggle them.  This can cause poor socket connections, which might have been my problem.  I think I'll contact Almarro (and BAT) to see if they have solved that problem and if I can get replacement sockets.  Big job, at 12 for the two amps!

 

Aside from all that, yes, excellent tubes, great clarity and linearity.  Great for OTL duty.

 

how much do these cost - just by curiosity

[LarryC]

how much do these cost - just by curiosity

You have a PM 

[richieb]

Larry

Both the manual and the tubes themselves are marked c-b. From what I've read and through correspondence Almarro sources tubes from Russian suppliers who pre-screen each tube prior to shipping to Japan. They are screened again prior to shipping the amps. It's either the amp design or tubes themselves but they have remained rock steady during first several hours, virtually no drift. The tubes should remain easily available as they have continued use in Russian MIG jet fighters.

Jez Larry, a dozen 6h33's! Where do you listen, a meat locker?! I bet they sound spectacular. Are they single ened or push/pull? I use only two and in my downstairs room there is virtually no heat. When I owned Audio Mirror monos (45 watts) two per block in an enclosed cabinet heat was an issue. Actually burned the finish from the wood!

I would have to assume your tube sockets have a receiver for the locating pin in the tube or they couldn't fit. So far the tubes fit good and tight but they are brand new.

[LarryC]

Both the manual and the tubes themselves are marked c-b. From what I've read and through correspondence Almarro sources tubes from Russian suppliers who pre-screen each tube prior to shipping to Japan. They are screened again prior to shipping the amps. It's either the amp design or tubes themselves but they have remained rock steady during first several hours, virtually no drift. The tubes should remain easily available as they have continued use in Russian MIG jet fighters. Jez Larry, a dozen 6h33's! Where do you listen, a meat locker?! I bet they sound spectacular. Are they single ened or push/pull? I use only two and in my downstairs room there is virtually no heat. When I owned Audio Mirror monos (45 watts) two per block in an enclosed cabinet heat was an issue. Actually burned the finish from the wood! I would have to assume your tube sockets have a receiver for the locating pin in the tube or they couldn't fit. So far the tubes fit good and tight but they are

Mine can be physically rocked in their sockets, so I assume it's an inadequate socket design.  Each amp has a meter that reads out a "filament voltage" figure, that is usually fairly stable (set at 64.0) except when neighborhood voltage drifts up or down a bit.  The same meters read out the bias (set at 27.0) by pushing a button next to each tube.  That figure drifts around a bit more even after warm-up, but can get pretty far off.  I believe my runaway problem, which affected one of the 6C's, resulted from a poor contact in the tube socket, perhaps due to the vulnerability of the tubes to rocking.

 

As I said, the heat is quite noticeable but not overpowering.  Perhaps yours run hotter. 

 

The circuitry is described as "single-ended" although 3 are run in some sort of opposite phase to the other 3 in each set of 6.  They are not push-pull according to my understanding.  P-P is usually in a transformer circuit isn't it?  There is no OPT in this amplifier.  There is only a variac to supply the filament voltage (or something like that).

 

He uses at least 6 tubes per side in order to get the output impedance down to near voice-coil level.  His larger models have many more 6C's each (see his website, e.g., http://www.joule-electra.com/pr_vzn220.htm).

Edited April 14, 2015 by LarryC

[LarryC]

I bet they sound spectacular. Are they single ened or push/pull?

The J-E website says they are "Single-ended asymmetrical Class A".  Although I don't understand what all that means, it is obviously a very esoteric design.  They are extremely transparent and full of accurately detailed sound.  At the same time, the output impedance is quite high (I don't know what it is), even with the 6 tubes per side, which results in a relatively thin bass and lower middle range.  I hope to try a pair of VRDs soon, to compare bass and accuracy of sound.

 

I haven't heard the 6C's in a P-P transformer amp, but would expect great clarity, accuracy and linearity.  How do you think they sound in your Almarro (I may have passed over it in your posts).

[richieb]

As you state it's the same in the Almarro; clarity, accurately detailed without being edgy and very well balanced. The Almarro is of single ended design so of course runs in Class A. No thin bass here and there was even more bass with the Audio Mirror monos but those ran at 45 watts SE vs 18 for the Almarro. Tubes are biased at 0.18 DCV with a trim pot for each tube. I adjusted one tube from 18.6 to 17.7 which is where both have remained. Output trannies are quite large and a huge power supply choke nestles between the two. The power transformer sits under the hood and is absolutely huge for the power rating. I imagine all the above keep the tubes in check. I have a 45 watt gain clone and there is no doubt these 18 watts play like 50, at least.

[OO1]

As you state it's the same in the Almarro; clarity, accurately detailed without being edgy and very well balanced. The Almarro is of single ended design so of course runs in Class A. No thin bass here and there was even more bass with the Audio Mirror monos but those ran at 45 watts SE vs 18 for the Almarro. Tubes are biased at 0.18 DCV with a trim pot for each tube. I adjusted one tube from 18.6 to 17.7 which is where both have remained. Output trannies are quite large and a huge power supply choke nestles between the two. The power transformer sits under the hood and is absolutely huge for the power rating. I imagine all the above keep the tubes in check. I have a 45 watt gain clone and there is no doubt these 18 watts play like 50, at least.

that good - wow

[NOSValves]

Larry

Both the manual and the tubes themselves are marked c-b. From what I've read and through correspondence Almarro sources tubes from Russian suppliers who pre-screen each tube prior to shipping to Japan. They are screened again prior to shipping the amps. It's either the amp design or tubes themselves but they have remained rock steady during first several hours, virtually no drift. The tubes should remain easily available as they have continued use in Russian MIG jet fighters.

Jez Larry, a dozen 6h33's! Where do you listen, a meat locker?! I bet they sound spectacular. Are they single ened or push/pull? I use only two and in my downstairs room there is virtually no heat. When I owned Audio Mirror monos (45 watts) two per block in an enclosed cabinet heat was an issue. Actually burned the finish from the wood!

I would have to assume your tube sockets have a receiver for the locating pin in the tube or they couldn't fit. So far the tubes fit good and tight but they are brand new.

Not trying to rain on your parade here...the almarro is a quality built and great sounding 6C33C amplifier but it will require matainance caused by the extreme currents that are running through those tube sockets it's the nature of the beast. The tube pin design on those tubes is the only reason I refuse to offer an amplifier designed around that tube. It's asking for trouble...the rusky engineers really f'ed up on that one... Edited April 15, 2015 by NOSValves

[NOSValves]

Both the manual and the tubes themselves are marked c-b. From what I've read and through correspondence Almarro sources tubes from Russian suppliers who pre-screen each tube prior to shipping to Japan. They are screened again prior to shipping the amps. It's either the amp design or tubes themselves but they have remained rock steady during first several hours, virtually no drift. The tubes should remain easily available as they have continued use in Russian MIG jet fighters. Jez Larry, a dozen 6h33's! Where do you listen, a meat locker?! I bet they sound spectacular. Are they single ened or push/pull? I use only two and in my downstairs room there is virtually no heat. When I owned Audio Mirror monos (45 watts) two per block in an enclosed cabinet heat was an issue. Actually burned the finish from the wood! I would have to assume your tube sockets have a receiver for the locating pin in the tube or they couldn't fit. So far the tubes fit good and tight but they are

Mine can be physically rocked in their sockets, so I assume it's an inadequate socket design. Each amp has a meter that reads out a "filament voltage" figure, that is usually fairly stable (set at 64.0) except when neighborhood voltage drifts up or down a bit. The same meters read out the bias (set at 27.0) by pushing a button next to each tube. That figure drifts around a bit more even after warm-up, but can get pretty far off. I believe my runaway problem, which affected one of the 6C's, resulted from a poor contact in the tube socket, perhaps due to the vulnerability of the tubes to rocking.

As I said, the heat is quite noticeable but not overpowering. Perhaps yours run hotter.

The circuitry is described as "single-ended" although 3 are run in some sort of opposite phase to the other 3 in each set of 6. They are not push-pull according to my understanding. P-P is usually in a transformer circuit isn't it? There is no OPT in this amplifier. There is only a variac to supply the filament voltage (or something like that).

He uses at least 6 tubes per side in order to get the output impedance down to near voice-coil level. His larger models have many more 6C's each (see his website, e.g., http://www.joule-electra.com/pr_vzn220.htm).

Being able to rock a tube in its socket is not a good way to determine if a socket is defective the tube is not suppose to be held tight by the socket, the metal tube pins should be firmly gripped by the metal contacts in the socket, that solid connection should float in the actual socket. Tube sockets regardless of quality are the weakest link in a tube based electronic device and require annual maintenance....cleaning and tensioning. Edited April 15, 2015 by NOSValves

[LarryC]

Not trying to rain on your parade here...the almarro is a quality built and great sounding 6C33C amplifier but it will require matainance caused by the extreme currents that are running through those tube sockets it's the nature of the beast. The tube pin design on those tubes is the only reason I refuse to offer an amplifier designed around that tube. It's asking for trouble...the rusky engineers really f'ed up on that one...

You're right.  That was my experience, which it cost me plenty as the amp was out of warranty, plus shipping cost.  However, the Almarro's socket looks different and I wonder if it's more secure. Right now, I think my problems have been with the sloppy socket design.

 

Also, the Joule doesn't have auto-biasing (not sure what that is), which requires added fuss and attention. 

 

BAT uses a lot of 6C33B tubes in their products, so I plan on calling them to see how they deal with the issue.  Also, I think Marty found a combination of a 6C tube that had a glass flange around the base that pushed into a holder as part of the socket.  It seemed to work really well. 

Edited April 15, 2015 by LarryC

[richieb]

Larry

The - the tubestore.com - has waht appears like the ceramic sockets in the Almarro, $7.00/ea. This looks like the top portion or square ceramic flange that the pins insert. What is required below or how it connects I have no clue.

I'm sure NOS is correct on the current levels associated with this tube which can't be avoided. I do know that the socket bolts and bias tabs, both out in the open, carry 100V DC. Couple that the 300C tube heat makes one cautious when biasing etc. To aid in heat dissapation each tube socket rests on stand-offs about 8-10mm off the deck surface and the area around each socket has about 40 1/8" holes in the deck for additional venting. 

[LarryC]

What great info, richieb!  I hope they can discuss options with me.  The Joule is fundamentally an advanced basement or workshop DIY product.  Ventilation is via large holes in the acrylic top plate, and that doesn't work real well in the long run.

[LarryC]

OK, I talked with BAT a few minutes ago.  The only socket available is the current Chinese white item, and I suspect that's what you and I both have.  The BAT tech said you have to insert the tubes carefully in order not to bend the pin spades which can break the contact with the tube pin.  But he readily agreed that the current socket doesn't grip the tube well.

 

BAT has had long experience using this tube and apparently believes it doesn't have big problems in the field.  I do think the potential is there, however.

Edited April 17, 2015 by LarryC

[thebes]

What I showed Larry were two original sockets.  One is the RCA UT-106 and the other is a contemporary, the Johnson 248/UT-106.

 

Both are available used, and NOS on ebay for reasonable prices given what they do.  The tube holders are a double clip, excepting the keyhole. Probably far superior to the knockoffs,. At least that was my impression when I looked over what was in Larry's amp.

 

Larry, of course, ignored my advice and bought the knockoffs.  He probably tosses and turns every night thinking about whether he made a mistake or not. But then he realizes that he's tossing and turning because of the lump of cash he saved bulging form under his mattress, and promptly falls back to sleep.

[LarryC]

Now, now, Marty.

 

I didn't think I could get even 6, let alone 12, of the superior sockets.  The repair guy I used didn't know about them and neither did the tube.com site, so I gave up.  Probably too soon.

 

Geez, if I could get 6 or 12, it would probably cost a bunch to pay someone to solder them in, but it might be worth it.

 

However, your pic doesn't show anything very different from what I have now.  Can you do one that shows the difference?

 

Thanks, Marty.  

 

 Larry

Edited April 18, 2015 by LarryC

[LarryC]

OK,  just talked with Marty -- he'd left me one of the Johnson tube sockets (apparently called a "wafer"?) that is definitely grippier than the knock-offs that Jud Barber installed in my newly purchased Joule amps.  We're getting together in 2 weeks, and will pull tubes and compare at that time.  If we judge I should change out all 12, I'll look around for someone to do it, starting with Craig if he wants the job.  There are other smaller tubes that sometimes need to have their sockets cleaned and reseated, so it's not just the large tubes.

 

There are a bunch of 7-pin sockets, some of which look like they might do the job: septar tube socket

 

However, the 6c may only fit into the Johnson and RCA sockets.

Edited April 18, 2015 by LarryC

[NOSValves]

What I showed Larry were two original sockets.  One is the RCA UT-106 and the other is a contemporary, the Johnson 248/UT-106.

 

Both are available used, and NOS on ebay for reasonable prices given what they do.  The tube holders are a double clip, excepting the keyhole. Probably far superior to the knockoffs,. At least that was my impression when I looked over what was in Larry's amp.

 

Larry, of course, ignored my advice and bought the knockoffs.  He probably tosses and turns every night thinking about whether he made a mistake or not. But then he realizes that he's tossing and turning because of the lump of cash he saved bulging form under his mattress, and promptly falls back to sleep.

 

 you sure that socket will even fit a 6C33?