Is their any other tube that can be substituted for the KT88? Can you like throw something else in and rebias?
Joe
Joe
DIFFERENCES
Hi,
Well,'fraid so.
As you know by now there are audible differences between one brand and the other for the same type this is even more true for substitutes.
The KT88 as I've known it from GEC was never a favourite of mine,
I've always prefered the 6550A which had better dynamics and bass response.
Since the original KT88 are long gone a few copies have turned up from various manufacturers and some are pretty good.
Just don't by the NOS Chinese coke bottle ones,they stink.
My favourite 6550 was the Tungsol which was kind of a magical match for the Jadis amps.
Other than finding these original US 6550As,I can recommend the Svetlana and JJ, both make the KT88 and 6550A.
Only difference is the bulb.
If you would like to read somebody elses' listening expererience here's a link:
ROMAN KLUN:
Cheers,😉
Hi,
Well,'fraid so.
As you know by now there are audible differences between one brand and the other for the same type this is even more true for substitutes.
The KT88 as I've known it from GEC was never a favourite of mine,
I've always prefered the 6550A which had better dynamics and bass response.
Since the original KT88 are long gone a few copies have turned up from various manufacturers and some are pretty good.
Just don't by the NOS Chinese coke bottle ones,they stink.
My favourite 6550 was the Tungsol which was kind of a magical match for the Jadis amps.
Other than finding these original US 6550As,I can recommend the Svetlana and JJ, both make the KT88 and 6550A.
Only difference is the bulb.
If you would like to read somebody elses' listening expererience here's a link:
ROMAN KLUN:
Cheers,😉
Frank
Thanks for the great link. It does however bring up more questions... Will the Electro-Harmonix 6550EH sub for the KT88?
Will the Sovtek 6550WE sub also? The Svetlana 6550C is a replacement for the 6550A.
Thanks
Joe
Thanks for the great link. It does however bring up more questions... Will the Electro-Harmonix 6550EH sub for the KT88?
Will the Sovtek 6550WE sub also? The Svetlana 6550C is a replacement for the 6550A.
Thanks
Joe
It's futile to talk about the sonic qualities of tubes independent of the circuit you use them in. Same with substitutions. Can you give us any details, ie P-P xformer impedance, O/P stage topology, B+. etc?
SY
All I can tell you is that I have a pair of Quicksilver KT88 Mono (60watt) Amps being shipped to me. These were manufactured in 1993 and have the following tubes... (2)KT88's,(2)5AR4's,and (2)12FQ7's in them. I don't know the power supply B+ or the circuit used. I have never personally heard this model of amp so maybe I made a very bad decision to purchase them.
Do to the fact that I'm sitting here bored I thought I would pose the question to see if their were other output tubes that would sub in this amp.
If someone happens to have a schematic of this amp I would love to see it.
Joe
All I can tell you is that I have a pair of Quicksilver KT88 Mono (60watt) Amps being shipped to me. These were manufactured in 1993 and have the following tubes... (2)KT88's,(2)5AR4's,and (2)12FQ7's in them. I don't know the power supply B+ or the circuit used. I have never personally heard this model of amp so maybe I made a very bad decision to purchase them.
Do to the fact that I'm sitting here bored I thought I would pose the question to see if their were other output tubes that would sub in this amp.
If someone happens to have a schematic of this amp I would love to see it.
Joe
QUICKSILVER
Hello,
The KT88 monoblock was the replacement of the 8417, a necessity when the tube manufacturer ceased production of the 8417 tube.
Setting the bias adjustment is easy. Simply insert the furnished meter into the plug, and with a screwdriver adjust the bias to 120 milliamps (115 mA is recommended for longer tube life). That's it. Of course, one should recheck the bias once every month or two, depending upon usage.
Input sensitivity is 1.25V for the given output into 1,4 or 8 Ohm.
IMHO differences amonhst output tube types and brands is always audible.
Which one is best suited is a matter of debate though.
Ciao,😉
Hello,
The KT88 monoblock was the replacement of the 8417, a necessity when the tube manufacturer ceased production of the 8417 tube.
Setting the bias adjustment is easy. Simply insert the furnished meter into the plug, and with a screwdriver adjust the bias to 120 milliamps (115 mA is recommended for longer tube life). That's it. Of course, one should recheck the bias once every month or two, depending upon usage.
Input sensitivity is 1.25V for the given output into 1,4 or 8 Ohm.
IMHO differences amonhst output tube types and brands is always audible.
Which one is best suited is a matter of debate though.
Ciao,😉
burnedfingers said:
Hoi there...No it's not......I could use trust the A version in lieu of KT88's as it has a higher plate voltage/screen rating.... but the B/ C/WA/WB versions have to dribble with a much lower rating.
The C is an overestimated tube.
I know the Tungsol 6550's coke bottles have been mentioned elsewhere on this thread......who's using 'em under wat conditions,......are they really better than the C Svetlana versions ? Does anyone have a spec sheet of them ?
rich
Tung-Sol
I think there's a spec sheet for them at the invaluable Frank's Electron Tube Pages. I've got a few NOS Tung-Sols which I had been using in a rebuild of an old Ampex power amp in pentode mode. They seemed to work really well, much more reliable than other 6550 contructions I've tried at the high voltages used in the Ampex (560V B+).
I think there's a spec sheet for them at the invaluable Frank's Electron Tube Pages. I've got a few NOS Tung-Sols which I had been using in a rebuild of an old Ampex power amp in pentode mode. They seemed to work really well, much more reliable than other 6550 contructions I've tried at the high voltages used in the Ampex (560V B+).
SY:
Sy et al,
Class A, P-P, Triode mode. What are your thoughts about that ? KT88 or 6550 ? and which brand ?
Sy et al,
Class A, P-P, Triode mode. What are your thoughts about that ? KT88 or 6550 ? and which brand ?
Up in the 500V bracket the KT88 /KT90/ EL34/807 are only my favorites for high B+.....the 6550A is rare now.....but a darned good tube....... if you want to run todays 6550's WA/WE/ C versions....... engineer with a lower B+ max i.e 450V B+ and perhaps avoid UL operation.....the GE orig 6550A spec sheet values doesn't hold for current clones.
Running a Svet 6550C at 500V B+ UL would have a short life...un like the GE A version.
rich
Not equivalents, but the 12E1 and S11E12 (special quality version) may be suitable for new amp designs as output valves where you might think of KT88 or 6550 and not have any on hand. They were designed for regulated power supplies and are really quite cheap. Pa max=35W, Va max = 800V, but Vg2 max = 300V which will cause angst in UL with high B+. Being designed with series-pass duty in mind, 300V is allowed between heater and cathode.
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