Enough Tubes For You?

[flez007]

In my experience, it is easier to get a tubed amp serviced than a SS one - tube circuits are rather simple, new SS designs are hard to fix and usually end at the manufacturer shop. I have been lucky enough for having very low incidents with my gear (including some cantilever "accidents") and of those, very few have been related to my tubed amps in the past.

 

[Gregadd]

Ralph's commentary is more interesting than the review. Not all is as it seems to be with transistor amplifiers.

Yes it is.
I am not sure but I think Brian actually filled an order for an MA-3. Rushton is runnig an MA2 with Walker tt and Avalon speakers. He makes regular appearences on Audiogon's "Whats Spinning Tonight" Thread.

 

[MylesBAstor]

In my experience, it is easier to get a tubed amp serviced than a SS one - tube circuits are rather simple, new SS designs are hard to fix and usually end at the manufacturer shop. I have been lucky enough for having very low incidents with my gear (including some cantilever "accidents") and of those, very few have been related to my tubed amps in the past.

One of the bigger problems with repairing some ss gear is that the parts go out of production really quickly and there are no comparable replacements.

 

[flez007]

One of the bigger problems with repairing some ss gear is that the parts go out of production really quickly and there are no comparable replacements.

I had accidentally shorted the speaker wires on a tube amp and had no further issues, I wonder what would happen if I did the same thing on my late Levinson!!!

 

[puroagave]

a lot of modern SS gear is now surface mount instead of through-hole. ever look inside a boulder? im not picking on them as many mfrs are going that direction. if MEP thought the ksa-250 was a bitch getting serviced try an amp whos pc boards are cluttered with SMT. the half-life of SS gear w/ SMT is 5-7 yrs by the 15-20th b-day it will turn into most expensive door stop you'll ever own

 

[mep]

Modern tube preamps are much better in this regard IMO. Better circuits, running the tubes more conservatively in their linear region, etc.

I have heard tube preamps, with MC tube phono-stages that have blacker backgrounds than very well regarded solid state preamps. One from Vacuum State the other the EAR 912. And my friend probably has well over 5000 hours in the tubes in his 912.

The EAR 912 uses SUTs for the phono stage in order to increase the gain and not tubes which would explain why it is so quiet. The stand-alone phono stage from Vacuum State is solid state. They do have a two-box tube preamp that has a phono section built into it, but I don't know which phono preamp you are talking about.

If you want to speak in general terms, no pure high-gain tube phono preamp will have noise levels lower than a well-designed SS phono stage because it just isn't possible given the realities of inherent tube noise vice SS devices that simply can't be designed around.

 

[mep]

One of the bigger problems with repairing some ss gear is that the parts go out of production really quickly and there are no comparable replacements.

This is true. My brother has a pair of the Counterpoint Progression monoblock amps and the IGBTs are out of production. Even before Mike closed his doors for good, my brother got the very last set of IGBTs that Mike had when he sent one of the amps back for repair.

 

[mep]

Frantz,

My original answer (that you quoted) was made to a generic Mep post about tubes versus SS maintenance and should have been taken with some humour. I answered with my MA2 experience. End of story. Re-read the thread and please do not distort my intentions.

And yes, I believe that a with the help of Ralph, any one used to work with tubes can service any Atmasphere amps, irrespective of price, most of the time. Just go tho the old Atmasphere forums and the OTL asylum and read the threads about this subject. I am not an expert and with the help of Ralph have carried upgrades of my MA2's several times.

My whole point really was that tubes by design will wear out/fail at some point in time. It’s just a given.
The more tubes you have, the more likely you are to experience a failure and the cost of replacing tubes increases as the tube count goes up. No surprises here. SS gear is not designed with socketed parts that are designed to wear out and be replaced by the end-user. If you buy a pair of tube amps with a zillion output tubes, even if they all die a natural death due to cathode depletion, it’s still going to cost you a fortune to re-tube it. And that is all fine assuming you have a fortune to spend. Of course if you could afford to buy these amps in the first place, you probably have the greenbacks it takes to keep them functional.

All audio gear will need servicing at some point in time if you own it long enough and that holds true for both SS and tube gear. Electrolytic power supply caps are usually rated for a 20 year life and it is common to replace them in older gear. I love that fact that my Amex 350s (which are the only tubes remaining in my system) have outboard tube power supplies with the main filter capacitor installed in a plug-in socket so it can be quickly replaced (which I have done and it took 2 seconds).

 

[mep]

Yeah Man, electrolytics are built in failure modes, just like tubes only their run time is longer. They tend to lose their capacitance and gradually wear out over time, too bad.

And bad electrolytic power supply caps are usually the cause of hum in old tube preamps and power amps. Back in the old days when tube amps used only tube rectifiers, the power supply filter cap (usually a multi-stage cap) was never very large to begin with in terms of microfarads. This was primarily because tube rectifiers can’t push a very big capacitor without arcing over. It’s quite common to see between 20-40 microfarads of capacitance in an old tube power supply. It’s also quite common for that 20-40 microfarad capacitor to become a 5 microfarad capacitor over time as the electrolytic cap dries out.

 

[XV-1]

Anyone who says that tube stereo gear isn’t a pain in the ass to own has never owned tube gear. As the number of output tubes increases, the pain in the ass factor increases exponentially. The most reliable tube amp I ever owned was my ARC D-76. One pair of GE 6550s per channel with bias ‘easy’ to set by using a DVM with a ¼ phone jack and care exercised not to burn your fingers as you plugged in the jack between the hot output tubes. Once you start doubling the amount of output tubes, reliability doesn’t increase I can assure you.

Tube preamps are another joy unto themselves. You are always fighting noise and microphonics. Quiet today and noisy tomorrow is the mantra or nightmare of tube preamps.

Is this a serious statement?

I have owned cj prem8a's for 13 years. Reliable as hell. 8x 6550's per side. Bias adjustment is as simple as using the adjustment screw clockwise until the light comes on, then back it off until the light is off. One light and adjustment per output tube.

The biggest hassle with cj tube amps are switching them on and off

 

[cjfrbw]

Any tube equipment that doesn't cause a temporary brown out in the street lamps is not enough tubes.

 

[mep]

Yes, it was a serious “general” statement about tube amps. CJ tube amps have always been among the easiest to set bias on. I have written numerous horror stories about other tube amps where setting the bias approaches brain surgery in difficulty and I’m not going to repeat all of it again. Some regular members on this forum have written about reliability issues with brand new expensive ARC gear.

Overall, I have had good luck with ARC reliability, but it’s always a crapshoot with ARC in terms of how hard they want to make your life in terms of setting the bias because it varies from the very easy (think D-79) to the borderline criminal (think D-70), to the absurd (think the VT-100 series). I now have an ARC VS115 tube amp which is still in production. It’s fairly easy to set the bias, but I sure have had easier amps to set bias on (think Quicksilver V4 amps-I can bias both amps in under 2 minutes). The bias adjustment tool has to be poked through a hole in the chassis and then you have to hunt and peck to find the bias adjustment pot and line up the tiny flat blade of the adjustment tool into the slot of the bias pot.

 

[MylesBAstor]

Is this a serious statement?

I have owned cj prem8a's for 13 years. Reliable as hell. 8x 6550's per side. Bias adjustment is as simple as using the adjustment screw clockwise until the light comes on, then back it off until the light is off. One light and adjustment per output tube.

The biggest hassle with cj tube amps are switching them on and off

Actually the biggest issue is when an output tube goes--and you're not watching--is figuring out which is the bad tube since there's only one fuse. You don't fully appreciate it until you use a VTL amp where it tells you which is the bad tube

 

[mep]

Actually the biggest issue is when an output tube goes--and you're not watching--is figuring out which is the bad tube since there's only one fuse. You don't fully appreciate it until you use a VTL amp where it tells you which is the bad tube

And this is coming from someone who owns and loves CJ amps.

 

[MylesBAstor]

And this is coming from someone who owns and loves CJ amps.

That's why have a tube tester But I appreciate what Luke has done with his amps!

 

[microstrip]

Yes, it was a serious “general” statement about tube amps. CJ tube amps have always been among the easiest to set bias on. I have written numerous horror stories about other tube amps where setting the bias approaches brain surgery in difficulty and I’m not going to repeat all of it again. Some regular members on this forum have written about reliability issues with brand new expensive ARC gear. (...)

Mep,

No, it was not a "general" statement - IMHO, it was a "particular" statement, motivated mainly by your recent bad relation with a Jadis amplifier, that is known to be expensive and critical to re-tube. I have read horror stories in forums about issues related to the distribution and service of Jadis in North America in the past. But they were mainly due to the distributors. A Jadis DA7 should be re-tubed with pre-aged and matched tubes. It uses a mix of cathode and grid bias - the pots were originally sealed, as it was not intended to be adjusted by the user. However, in order to use cheaper non-officially Jadis supplied tubes, or perhaps because they were not available locally, people started fiddling with the pots. Start of horror stories.

It always easy to get a negative impression from ex-owners in forums - they seem very happy to tell their problems. But hundreds of happy loyal happy owners mostly remain silent. I know of a few people who own Jadis in my country - one even has four JA200s in by-amp. And they are happy, any issue they will have will be promptly solved by our local distributor - the same who distributes Krell and ARC.

People buying tube equipment must remember that no tube equipment can be more reliable than its tubes. A few badly designed amplifiers had great problems in the past, when a bad tube would almost destroy all the amplifier. These brands either learned fast from their mistakes or plunged down. If you buy carefully from good distributors, tube equipment can give you a long life of enjoyment and pleasure.

 

[mep]

Well, the good news is that if a CJ amp has a tube blow up, it takes out a fuse. ARC amps are designed to use cathode resistors as fuses when a tube blows so now you have to take the amp apart, remove the blown cathode resistor and solder in a new one. This is beyond the capabilities of lots of tube amp owners which means the amp has to go back to the dealer or ARC for repair.

 

[mep]

Mep,

No, it was not a "general" statement - IMHO, it was a "particular" statement, motivated mainly by your recent bad relation with a Jadis amplifier, that is known to be expensive and critical to re-tube. I have read horror stories in forums about issues related to the distribution and service of Jadis in North America in the past. But they were mainly due to the distributors. A Jadis DA7 should be re-tubed with pre-aged and matched tubes. It uses a mix of cathode and grid bias - the pots were originally sealed, as it was not intended to be adjusted by the user. However, in order to use cheaper non-officially Jadis supplied tubes, or perhaps because they were not available locally, people started fiddling with the pots. Start of horror stories.

It always easy to get a negative impression from ex-owners in forums - they seem very happy to tell their problems. But hundreds of happy loyal happy owners mostly remain silent. I know of a few people who own Jadis in my country - one even has four JA200s in by-amp. And they are happy, any issue they will have will be promptly solved by our local distributor - the same who distributes Krell and ARC.

People buying tube equipment must remember that no tube equipment can be more reliable than its tubes. A few badly designed amplifiers had great problems in the past, when a bad tube would almost destroy all the amplifier. These brands either learned fast from their mistakes or plunged down. If you buy carefully from good distributors, tube equipment can give you a long life of enjoyment and pleasure.

Mine was the Defy 7 MKII and I bought a new set of GL KT-88 reissue tubes from Kevin Deal which wasn't cheap. You are never going to get 3 output tubes to match perfectly, and even if you could, they won't stay matched perfectly over their lifetime. When you only have one bias pot for each bank of three output tubes, this becomes critical. You are now faced with the fact that you can't set bias perfectly for each output tube and you are setting an average bias across the bank of three. Yee-Haw. And because checking/setting the bias on a Defy 7 is such a pain in the ass, it tends to cause you to check it less often than you normally would if it was easy.

 

[microstrip]

Actually the biggest issue is when an output tube goes--and you're not watching--is figuring out which is the bad tube since there's only one fuse. You don't fully appreciate it until you use a VTL amp where it tells you which is the bad tube

An old trick that works almost always. If a V+ fuse blows, replace it with an inexpensive fast one having approximately a little above the value of all the bias currents summed. Switch the amp on in the darkness looking at the tubes - most probably it will blow again, but the faulty tube will emit a visible blue flash. I also have a tester, but this receipt is faster.

Do not try this looking at the transistors of your amplifier if it blows a rail fuse - most probably next time you will see lots of smoke.

 

[microstrip]

Mine was the Defy 7 MKII and I bought a new set of GL KT-88 reissue tubes from Kevin Deal which wasn't cheap. You are never going to get 3 output tubes to match perfectly, and even if you could, they won't stay matched perfectly over their lifetime. When you only have one bias pot for each bank of three output tubes, this becomes critical. You are now faced with the fact that you can't set bias perfectly for each output tube and you are setting an average bias across the bank of three. Yee-Haw. And because checking/setting the bias on a Defy 7 is such a pain in the ass, it tends to cause you to check it less often than you normally would if it was easy.

The Defy 7 mk2 had the same output stage biasing scheme as the DA7. It had individual cathode degenerative bias resistors - small variations due to normal aging of the specified quality tubes would be absorbed by them. Were the GL KT-88 endorsed by Jadis?