Hi Chris.
Thanks for your reply.
Funny thing is, that i really like the sound of it, but then again, i have nothing to compare with. I have never had a tube amp before. Compared to my Audioanalyse class A, it's more pleasing to my ears, that's as close i can describe it 🙂
It's been running for about a year now, with no other fault than the trimmer-pot, that had a bad connection. I don't use it every day, but now i wonder if i should get me two pair of EL-34 instead, and at the same time get me some sockets.
Oh, i looked at the cases once more, .
and one of them had a sticker, saying that it's Sovtek 6L6GT.
Thanks for your reply.
Funny thing is, that i really like the sound of it, but then again, i have nothing to compare with. I have never had a tube amp before. Compared to my Audioanalyse class A, it's more pleasing to my ears, that's as close i can describe it 🙂
It's been running for about a year now, with no other fault than the trimmer-pot, that had a bad connection. I don't use it every day, but now i wonder if i should get me two pair of EL-34 instead, and at the same time get me some sockets.
Oh, i looked at the cases once more, .
and one of them had a sticker, saying that it's Sovtek 6L6GT.
Hi Ebbe,
What some people will not do.
EL34's are much thinner than 6L6GC and 6CA7. My normal action if I were repairing it would be to install 6CA7EH and a socket. The other bracket needs to be cut to allow the hight. Do it and make up another pair based on the ones you have in your hand.
-Chris
🙄
What some people will not do.
EL34's are much thinner than 6L6GC and 6CA7. My normal action if I were repairing it would be to install 6CA7EH and a socket. The other bracket needs to be cut to allow the hight. Do it and make up another pair based on the ones you have in your hand.
-Chris
AMC CVT 2030 Output Transformer
Hello all!
I noticed a lot of talk on the AMC CVT3030. Having been involved in the AMC products for some time I am sorta 'biased' toward them. (aah come on not even a chuckle?)
Anywho, the CVT3030 integrated is a pretty special amplifier having created a new category for the hifi market. Mosfet front-end and class A output makes for a pretty good sounding 30 watt piece of hardware. One time I checked the frequency response of the preamp section of the CVT3030 and was unable to measure the distortion with the B&K analyzer I was using. In otherwords better than 0.01% distortion. Over the cource of time we were able to eliminate most of the long term things that plagued the owner usually after playing it for a year or more.
One of the things addressed was the heater supply broblems. Each output module heater circuit idled at around 6 amps of current. A total of 12 amps at the power supply board The connectors used were found not to handle the long term requirementsBest thing to do is solder two wires from the power supply circuit board directly to the output circuit board. First remove the 2 pins of the 12 pin output module connector. This will make better connections and will not 'arc out' creating the burnt carbonised center you described. Yes the blackened area does have reisitance effectively shorting out the area between it.
Hope this helps some of the long ternm issues. More soon
Dave
Hello all!
I noticed a lot of talk on the AMC CVT3030. Having been involved in the AMC products for some time I am sorta 'biased' toward them. (aah come on not even a chuckle?)
Anywho, the CVT3030 integrated is a pretty special amplifier having created a new category for the hifi market. Mosfet front-end and class A output makes for a pretty good sounding 30 watt piece of hardware. One time I checked the frequency response of the preamp section of the CVT3030 and was unable to measure the distortion with the B&K analyzer I was using. In otherwords better than 0.01% distortion. Over the cource of time we were able to eliminate most of the long term things that plagued the owner usually after playing it for a year or more.
One of the things addressed was the heater supply broblems. Each output module heater circuit idled at around 6 amps of current. A total of 12 amps at the power supply board The connectors used were found not to handle the long term requirementsBest thing to do is solder two wires from the power supply circuit board directly to the output circuit board. First remove the 2 pins of the 12 pin output module connector. This will make better connections and will not 'arc out' creating the burnt carbonised center you described. Yes the blackened area does have reisitance effectively shorting out the area between it.
Hope this helps some of the long ternm issues. More soon
Dave
Hi Dave,
A pair of EL34's per channel would be about 3.2 amps of heater current. Using a screw terminal block would be better than the connector. Soldering makes working on these even harder. The original plan to solder the tubes right in was a deadly poor decision in my estimation.
The arcing between pads is caused by factors not connected to poor terminal contact.
-Chris
A pair of EL34's per channel would be about 3.2 amps of heater current. Using a screw terminal block would be better than the connector. Soldering makes working on these even harder. The original plan to solder the tubes right in was a deadly poor decision in my estimation.
The arcing between pads is caused by factors not connected to poor terminal contact.
-Chris
I would suggest completely disconnecting all wires to the output transformer...then apply a small AC voltage to the secondary, such as your 6.3V heaters, bring it up slowly with a variac, then check the AC voltage you get across your full primary side... This is just a rough way to see what is happening...
Also...I read somehere about this amp... "check the zener diode and resistor on the output transformer which are the first to go in a tube failure"
Chris
Also...I read somehere about this amp... "check the zener diode and resistor on the output transformer which are the first to go in a tube failure"
Chris
anatech said:
Ouch, that hurts...... Well, i must admit, that the guy i bought it from sounded like he knew what he was talking about, he delivered the 4 new tubes when i picked up the amplifier, telling me they were nearly identical. He even told me he prefered the 6L6 over the EL-34.
I'm afraid it will be difficult getting these tubes out in one piece if i wanted to change to EL-34 now. In that case i need to make two new pcb's, just to avoid cutting those 6l6's.
Well, i see a new project for the future, no need to get bored in this house, hehe.
Hey Chris,
feel much better...
"Each output module heater circuit idled at around 6 amps of current. A total of 12 amps at the power supply board The connectors used were found not to handle the long term requirementsBest thing to do is solder two wires from the power supply circuit board directly to the output circuit board."
Yep, you are correct. Sorry, i must have doubled the current in my mind. The roasting problem I was talking about earlier was related to the heating of the terminals over a long period of time. The high heat chars the CB between the pins and eventually causes a low impd. short-especially between the high-voltage terminals. The screw terminal upgrade proved well but for the units that are 'upgraded' in basements soldering will work too.
Dave
feel much better...
"Each output module heater circuit idled at around 6 amps of current. A total of 12 amps at the power supply board The connectors used were found not to handle the long term requirementsBest thing to do is solder two wires from the power supply circuit board directly to the output circuit board."
Yep, you are correct. Sorry, i must have doubled the current in my mind. The roasting problem I was talking about earlier was related to the heating of the terminals over a long period of time. The high heat chars the CB between the pins and eventually causes a low impd. short-especially between the high-voltage terminals. The screw terminal upgrade proved well but for the units that are 'upgraded' in basements soldering will work too.
Dave
Hi Dave,
I have seen terminals overheating, possibly in more humid climates there is more water absorption? They normally get all ugly and burnt, but don't arc up here from what I've seen. Perhaps a cut between with a Dremel cut off wheel may work to fix it?
Dave, a thought. Have you ever attempted to install 6CA7EH in these? I get improvements in most EL34 amps, on the meter and listening.
Hi es44,
Good sound will normally occur with lower THD readings when tubes are being swapped around. Design by ear normally means the person has no technical knowledge (not real knowledge anyway). If you want that, buy a Counterpoint or Elliot and get on the modder-go-round. Bring cash.
You can desolder these tubes without destroying them. It just takes a long time. Dave has a special attachment made for this job. Wish I had one but the cost is very high for this attachment.
-Chris
Happens to me all the time. I try to double check these days when I post but don't catch everything.
I have seen terminals overheating, possibly in more humid climates there is more water absorption? They normally get all ugly and burnt, but don't arc up here from what I've seen. Perhaps a cut between with a Dremel cut off wheel may work to fix it?
Dave, a thought. Have you ever attempted to install 6CA7EH in these? I get improvements in most EL34 amps, on the meter and listening.
Hi es44,
There are so many idiots out there with a soldering iron waiting to destroy equipment! This drives me crazy. Just think, he changed to outputs but did not install tube sockets. The elevator failed to reach the upper floors.
Good sound will normally occur with lower THD readings when tubes are being swapped around. Design by ear normally means the person has no technical knowledge (not real knowledge anyway). If you want that, buy a Counterpoint or Elliot and get on the modder-go-round. Bring cash.You can desolder these tubes without destroying them. It just takes a long time. Dave has a special attachment made for this job. Wish I had one but the cost is very high for this attachment.
-Chris
anatech said:
A 6L6GC will certainly fetch less power and up the higher harmonics in an EL34 optimized position. 6CA7 RCA, & GE NOS, are better sounding bulbs than garden variety new production EL34. Best I ever heard was EL34 Telefunken, metal base 1950's, but this I mention just for reference. Obtainable and for sane money, I would install =C= EL34s. Better sound close to the Mullard archetype, vs all the Reflektor factory, Saratov-Russia made, New Sensor old logo acquired stuff. No problem with any EH,Sovtek,Svetlana,Mullard,TungSol, made there, just a little rougher HF.
Dave, a thought. Have you ever attempted to install 6CA7EH in these? I get improvements in most EL34 amps, on the meter and listening.
Hey Chris,
I haven't even thought about it. Now that I think about it I wonder why... I guess we have enough to do just keeping these things glowing. I've been seeing tubes coming out of Russia with dual ratings like above but hearing/seeing they are more of one type/specification than another. I don't think this will be a problem comming out of the EH lineup.
I've got a bread board version of a CVT3030/2030 on my bench with all but one channel. I would like to hunt down some 6CA7's and do some 'smoking'.
Dave
Hey Chris,
I haven't even thought about it. Now that I think about it I wonder why... I guess we have enough to do just keeping these things glowing. I've been seeing tubes coming out of Russia with dual ratings like above but hearing/seeing they are more of one type/specification than another. I don't think this will be a problem comming out of the EH lineup.
I've got a bread board version of a CVT3030/2030 on my bench with all but one channel. I would like to hunt down some 6CA7's and do some 'smoking'.
Dave
Can anyone email me service manual or schematics on 3030 (a) ?
my address is ipb399 <nospam> mail.ru
my address is ipb399 <nospam> mail.ru
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