Tube Rolling w/Crack
- Thread starter Dr. Toobz
- Start date
Paul Joppa
Moderator
6520 is - supposedly - a well balanced 6AS7G. The only one I ever saw was not at all well balanced between sections, so caveat emptor, but it should be otherwise identical to a 6AS7G.
Paul Joppa
Moderator
Because the Crack output is a cathode follower, the gain difference will be much smaller than any difference in mu or gm (tube parameters). All tubes will have some difference in gain due to manufacturing variations, which though possibly audible are much much smaller than differences among solid-state devices. This is one of the things that makes it possible to forgo negative feedback in tube devices.
Hi all,
I am enjoying my E80CC very much. Juicy sounding, like an old english radio, and very detailed/clear. Percussion and wind Instruments are grand with this tube. Soundstage nearly as good...or maybe as good, as the Mullard CV4003...
Had a question though, I see the E80CC's advertised as both replacements for 12au7's and in yet other ads, as replacements for 12ax7's. Can the later be true? If so I'll try them in my phono stage as well...
Thanks in advance!
I am enjoying my E80CC very much. Juicy sounding, like an old english radio, and very detailed/clear. Percussion and wind Instruments are grand with this tube. Soundstage nearly as good...or maybe as good, as the Mullard CV4003...
Had a question though, I see the E80CC's advertised as both replacements for 12au7's and in yet other ads, as replacements for 12ax7's. Can the later be true? If so I'll try them in my phono stage as well...
Thanks in advance!
Paul Joppa
Moderator
They are lying. E80CC takes twice the heater current of either 12AX7 or 12AU7, and has a gain of 27, not very close to 100 or 17 respectively. It will "work" in some circuits, that is sound will come out, but not the way the designer intended. In some cases it can do some damage. I think this has been covered in another thread ...
langendorf said:Thank you all for the feedback.
I ordered the mullard and cifte tubes in platinum grade. But not with cryo threatment, i want to hear the original sound. May order some later to hear the difference
Know i just hope the crack will respond well to good tubes
Langendorf,
I did the same. I just put the Mullard in after listening to the CIFTE for a couple of weeks. I really like the CIFTE, becuase of its detailed sound and nice exstention. I have only listened to the Mullard for a couple of hours, but this is a very nice sounding tube as well. It seems to have a warmer sound. Not sure which I like better, but can say that this has been the biggest improvement in sound.
What do you think of the Mullard and CIFTE tubes?
Now I'm looking at what I want to try in place of the 6080.
Paul Joppa
Moderator
Because of the cathode follower output, Crack is relatively tolerant of "similar" tubes - I really should have said something about that, I was just focused on the broader claim that you can use one tube in place of another when they are that different. A lot of tube sellers do this and it really bugs me. But I apologize for getting off the Crack topic.
When you change the tube parameters, the operating points (voltages and currents) will normally change. The Speedball will eliminate the current differences, but the voltage differences may be larger. If you would post the voltages on the tubes, I can make some comments on why it might sound different - from a technical perspective of course. But there is more than simple technology at work in the way a tube sounds. If you hear a difference, there almost certainly is a difference!
What are you using for the output tube?
When you change the tube parameters, the operating points (voltages and currents) will normally change. The Speedball will eliminate the current differences, but the voltage differences may be larger. If you would post the voltages on the tubes, I can make some comments on why it might sound different - from a technical perspective of course. But there is more than simple technology at work in the way a tube sounds. If you hear a difference, there almost certainly is a difference!
What are you using for the output tube?
Thanks Paul, I can see now why u might be peeved at that. I've seen other outlandish claims on e-bay as well. Down right entertaining - u guys just starting out should be very wary of the tube museum guy, why he's still up I just don't understand. Hope I won't get in trouble for that comment. Just check it out, the audiogon forum has allot on him, and his listing that I last saw (was it last week?) is another head scratcher.
Anyways,
I usually run a power/output tube-WE 421a...but when the E80CC was in I was running a svetlana 6H13 (I think they are similar, except that you can get 15 svetlana's for the price of 421a). I'm keeping that in while I do some heavy input tube rotations/comparisons for consistency. I'm about through this round and will put the WE-421a back in and start over again! Good thing there are only 2 tubes on this puppy.
PS: Now I'm having trouble swapping-out the bugle boy 7316....another winner <
Anyways,
I usually run a power/output tube-WE 421a...but when the E80CC was in I was running a svetlana 6H13 (I think they are similar, except that you can get 15 svetlana's for the price of 421a). I'm keeping that in while I do some heavy input tube rotations/comparisons for consistency. I'm about through this round and will put the WE-421a back in and start over again! Good thing there are only 2 tubes on this puppy.
PS: Now I'm having trouble swapping-out the bugle boy 7316....another winner <
R
Raksasa
Guest
Hi All,
Still loving my Speedballed Crack with my Beyer DT 880 600 ohm Manufaktur HPs (Meier Audio Corda StageDAC from PC).
Have been using an old CBA 7236 with a CBS 12BH7A. Decided to try some of my other tubes for a change.
Listening to a Mullard CV 4003 with a Russian Winged C (OTK) 6H13C. Very nice combination.
Does anyone know anything about "running in" tubes ? Is it fact or fallacy ?
All the best,
John T (from Downunder).
Still loving my Speedballed Crack with my Beyer DT 880 600 ohm Manufaktur HPs (Meier Audio Corda StageDAC from PC).
Have been using an old CBA 7236 with a CBS 12BH7A. Decided to try some of my other tubes for a change.
Listening to a Mullard CV 4003 with a Russian Winged C (OTK) 6H13C. Very nice combination.
Does anyone know anything about "running in" tubes ? Is it fact or fallacy ?
All the best,
John T (from Downunder).
Paul Joppa
Moderator
The known technical aspects of "running in" (we call it burning in - but then, we cal it "English" too!) have to do with the cathode.
The cathode is fairly complex and dynamic at a molecular level, and was only beginning to be understood when transistors supplanted tubes and research lost interest. Two things are known though:
1) the cathode must be formed. This is done in the factory, and consists of running some current through it; sometimes at slightly elevated temperature. It normally takes some 50-100 hours. Supposedly it brings or exposes individual barium and strontium atoms at the surface. Also, some trace elements of the substrate alloy diffuse into the coating. (In fact, a bit of silicon in the nickel substrate is known to speed the forming but shorten the working lfe of the cathode.)
2) many kinds of cathode will form a resistive layer between the substrate and the coating if they are operated for a long time with no current. This layer limits the emission, and adds noise. It is plausible that it can be reversed by running some current.
I am not aware of any studies of long-term storage, but since cathodes are known to be chemically active through their life it seems reasonable that the would require re-forming if they have sat idle for decades.
For what it's worth, I measured some of the earliest modern 300Bs (I think they were Sovteks, the first production run) a long time ago and found that their cathodes were not initially capable of providing their proper current. After 24 hours they were significantly improved, and after several days they met their specs easily, and I ran one pair of them for several years with no problem.
Also for what it's worth, remember that the getter, which traps ions to maintain the vacuum, only works when it's hot. A tube that has been idle for an extended period may have become slightly gassy, and operating at temperature would allow the getter to resolve the problem.
The cathode is fairly complex and dynamic at a molecular level, and was only beginning to be understood when transistors supplanted tubes and research lost interest. Two things are known though:
1) the cathode must be formed. This is done in the factory, and consists of running some current through it; sometimes at slightly elevated temperature. It normally takes some 50-100 hours. Supposedly it brings or exposes individual barium and strontium atoms at the surface. Also, some trace elements of the substrate alloy diffuse into the coating. (In fact, a bit of silicon in the nickel substrate is known to speed the forming but shorten the working lfe of the cathode.)
2) many kinds of cathode will form a resistive layer between the substrate and the coating if they are operated for a long time with no current. This layer limits the emission, and adds noise. It is plausible that it can be reversed by running some current.
I am not aware of any studies of long-term storage, but since cathodes are known to be chemically active through their life it seems reasonable that the would require re-forming if they have sat idle for decades.
For what it's worth, I measured some of the earliest modern 300Bs (I think they were Sovteks, the first production run) a long time ago and found that their cathodes were not initially capable of providing their proper current. After 24 hours they were significantly improved, and after several days they met their specs easily, and I ran one pair of them for several years with no problem.
Also for what it's worth, remember that the getter, which traps ions to maintain the vacuum, only works when it's hot. A tube that has been idle for an extended period may have become slightly gassy, and operating at temperature would allow the getter to resolve the problem.
R
Raksasa
Guest
Thanks very much Paul. Good to see some technical explaination.
I had heard references to old tubes getting "gassy" previously.
Cheers,
John T.
I had heard references to old tubes getting "gassy" previously.
Cheers,
John T.
The GEC is warming up now and sounding better all the time. It was NOS so it may take some time, the first post about it was only about 10 minutes in the amp. I have to do some direct comparisons, but the GEC 6AS7 Brown Base sounds like the one I keep in it. Nice sounding tube if you can find one. Took me months.
ELBEBE1000
New member
Hi,
I quick question. What would be better on crack with speedball telefunken ECC82 or Mullard 12AU7?
Thank you.
I quick question. What would be better on crack with speedball telefunken ECC82 or Mullard 12AU7?
Thank you.
