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Are these type tubes different or are they just a horse of a different color? Thanks
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From the datasheets:
KT88 maximums:
600V plate
600V g2
35W plate dissipation
6W G2 dissipation
6550 maximums:
660V plate
440-500V g2 (440 for pentode, 500 for triode/UL)
42W plate dissipation
6W G2 dissipation
This data indicates that you could design a KT-88 amp that really shouldn't use 6550's, but not the other way around. For Hifi amps, these differences can largely be disregarded, and the plate curves are similar.
specs have changed over years. ORiginal 88's could take 800volts maximum plate voltage.
Yeah, I think the GEC specifications were a little optimistic, so I pulled from the Genalex sheet that came out 3 years after introduction.
think your 6550 specs are also optimistic. IIRC Dave Manley developed kt 90's because, first KT 88's disappeared then GE 6550a's could not handle B+ voltages past 600 volts. Back then he ran his B+right at 600
Thanks for the information. Now I know that they are not the same.
Well they are interchangeable depending on your amp. I have had more failures with KT-88 that 6550 in my ARC amp. I have decided to avoid KT-88. But I know other amps work just fine.
Sort of like a 6DJ8,ECC88 and a 6922 preamp type tube. I am curious if is the same.
This could be interesting, if enough reply.
I was recently surprised to see that Manley differentiates sonics between the EL-34 and 6CA7 tubes. I always assumed there were basically identical, just different numbering between US and European brands, the same as for KT-88 and 6550.
This is not to say there are not favorites (brand wise) within each type. But I also assumed that related to specific design, rather than label.
So hopefully some Inmates with deep tube knowledge will respond.
"You can’t know what the “best” is unless you have heard everything, and keep in mind that given individual tastes, there really isn’t any such thing." HP
The EL34 and 6CA7 have different internal construction - the 6CA7 is a beam power tube, the EL34 is a true pentode. That accounts for some of the difference in tone.
For those like myself with little background in electronics, what are the relative benefits for each between beam power tubes and true pentodes? I'm most interested in accurate musical tonality.
Thanks.
"You can’t know what the “best” is unless you have heard everything, and keep in mind that given individual tastes, there really isn’t any such thing." HP
The reason the 6CA7 and other "beamies" came about IIRC was to avoid a patent conflict with Philips. The tubes have slightly different interelectrode capacitances, lower screen current, etc. which cause small changes in audio performance but most of the difference in this case had little/nothing to do with tone.
That was my first question when I got my Octave. I never got a straight answer other than you need to try them all. My Octave V70se came with SED KT88's and I immediately bought a quad of SED 6550's. Well the 6550 is very linear from top to bottom but dry sounding. The KT88 was much warmer (more low end with slightly rolled off highs). Next were Gold Lion KT88 re-issue. They are like a cross between the SED 6550 and KT88. Then I splurged and got some original Tung Sol 6550 solid black and grey plates. Very similar to the EL34 sound (glorious mids) but punchier (more power of course)with much better lows and highs although the highs are ever so slightly rolled off. Next up were the original GEC KT88 and EAT *KT88 Diamonds. The GEC is like the SED 6550 but with better lows and highs and slightly dry sounding. The EAT is the most linear accurate (detailed) sounding tube (excellent lows mids and highs) and no dryness.
So there you have my experience. I have some 6550's that sound linear and some that sound warm. Same for the KT88's.
That said I have a tube that I would say is a cross between the EAT KT88 and the TS 6550 grey plate (black plate is a hair warmer) leaning on the EAT side. It's neither. It's the Ei KT90 type 2 or 3 (Thanks Jim McShane for telling me about them!!!!). Great all rounder.
What I found interesting was when I had the Dynaudio C1 Sig speakers the TS 6550 black plates sounded the best to me and everyone who heard them. Ei KT90's second. I didn't care for the SED 6550 Gec KT88 and EAT KT88. I then upgraded to the Raidho D1 and today D2's (also upgraded the Octave to the V110). The TS 6550 black plates sound the worst. I have been staying with the KT90's for the Raidho's.
*EAT KT88's - I had a tremendous failure rate in my Octave V70se. Out of 6 I lost 3 within 60 hrs. I also lost 1 of 4 KR Audio KT88's in 20 hrs (KR Audio KT88's were made by EAT).
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