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Old 31st October 2008, 12:14 AM   #1
N1ESE is offline N1ESE  United States
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Default KT88 Electro-Harmonix

I've been thinking of KT88's for my first amp build and noticed these budget KT88's on Jim McShane's tube inventory list. Does anyone have any experience with the Electro-Harmonix KT88's? Jim wrote the following on his site:

Quote:
KT-88 Electro-Harmonix . This tube has 95% of the performance of the very best KT-88s at 1/2 the price! Very tight bass (I wish there was a tad more of it though), beautiful mids and highs - and a tough, reliable tube too. Only $59.50/pair, $114.50/quad. Note! If you want to use these in a Harman-Kardon Citation II amp you must reduce the bias current to 83-85 ma. or so to stay within the tubes' dissipation limits.

They do nothing for me in triode though - the Ei KT-90s in triode still KILL anything else in triode. I recommend using the EH in the stock (ultralinear) configuration only.
Thanks
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Old 31st October 2008, 12:18 AM   #2
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For $60 a pair, how can you go wrong? You'll pay that much for some premium branded EL34 or 6CA7.
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Old 31st October 2008, 12:21 AM   #3
N1ESE is offline N1ESE  United States
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Originally posted by Ty_Bower
For $60 a pair, how can you go wrong? You'll pay that much for some premium branded EL34 or 6CA7.
Exactly what I was thinking. I've decided to go with better output transformers and delaying the purchase of Genalex KT88's for now so I was looking at premium EL34's when I noticed these.
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Old 31st October 2008, 01:00 AM   #4
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These are for the Simple SE you are building, correct? If you want a really cheap set of starter tubes to prove it works (before you blow up an expensive set of "good" tubes), you could try the 6L6GC RECEIVING TUBE off eBay. I bought a bunch off the guy and they seem to work just fine. Can't argue with the price, either. Ask him about combined shipping on multiple tubes.
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Old 31st October 2008, 01:08 AM   #5
N1ESE is offline N1ESE  United States
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Quote:
Originally posted by Ty_Bower
These are for the Simple SE you are building, correct?
Correct. I'll look at keeping a cheap set of 6L6GC's on hand for testing, definitely a good idea. The person you referred to doesn't have any listed at the moment but these are common tubes on eBay. I'm ordering all my parts for this build on Monday so I will keep my eyes open on eBay this weekend. Thanks, as always, Ty.
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Old 31st October 2008, 01:54 AM   #6
n_maher is offline n_maher  United States
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Quote:
Originally posted by N1ESE


Correct. I'll look at keeping a cheap set of 6L6GC's on hand for testing, definitely a good idea. The person you referred to doesn't have any listed at the moment but these are common tubes on eBay. I'm ordering all my parts for this build on Monday so I will keep my eyes open on eBay this weekend. Thanks, as always, Ty.

Let me know if you need some 12AT7s for testing as well. I bought a bunch of used/tested tubes on Ebay and could loan you a few.
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Old 31st October 2008, 02:15 AM   #7
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I use them. I think they sound good.
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Old 31st October 2008, 02:22 AM   #8
chrish is offline chrish  Australia
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This is a great experimenter amp. You can try ultralinear/triode and a whole bunch of different tubes. I think a great idea is to have switcheable cathode resistance to best suit different output tubes. See this thread http://www.diyaudio.com/forums/showt...65#post1526165

If you want cheap 6L6 type, I have tried these with success http://cgi.ebay.com/RARE-5881-6L6GC-...arms=72%3A1209|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3286.c0 .m14

These 6P3S-E version appear to have better plate dissipation than the cheaper 6P3S. I have tried JJ E34L, winged =C= EL34, 6P3S, 6P3S-E, JJ KT88 in this amp and with my setup (smaller edcor transformers XSE 15-8-5K and active crossover at 80Hz and subs) the JJ E34Ls are what keep getting put back in. More clarity and detail than the KT88s. The KT88s had less mid range clarity and were a little muddy/boomy in the bass. Mind you, my crossover and subs may have contributed to the sound, and if you have larger output transformers and main speakers capable of lower freqs than mine, the KT88s may be a better setup.

BTW, have tried Mullard, JAN(GE), and JJ ECC81, and really cannot tell much difference. The JJ works well and is cheap!

Whatever you do, you will enjoy the amp!

Cheers,

Chris
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Old 31st October 2008, 02:35 AM   #9
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Quote:
I've been thinking of KT88's for my first amp build and noticed these budget KT88's on Jim McShane's tube inventory list.
I have a Simple SE that uses EH KT88's. These tubes give up a little bit of detail in exchange for power and bass that is uncharacteristic of an SE amp. When played through my 96db home made speakers that have 15 inch woofers the bass can be heard inside the house across the street. I got 6 of these tubes used for $10 each. I put one pair in this amp when I made it, and they have never been removed. I often run them hot (100 mA) and they don't seem to mind.

The cheap Chinese 6L6GC is a good tube to experiment with but it is not the best sounding tube. I have three Simple SE's. This one has the EH KT88's, it is the amp to use when I want to get loud or play rock music. Number two gets used for more mellow stuff like Norah or Sade. It uses JJ EL34's. The third amp has 6V6's and the cheap Edcor OPT's most of the time but it is the amp that I use for experiments so it is dead a lot too. I have blown it up at least a dozen times. The little Edcors really do sound good when you don't ask them to handle more than 1 or 2 watts. Above that level some saturation distortion becomes evident on strong low frequency material.
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Old 31st October 2008, 05:18 AM   #10
Zap is offline Zap  United States
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I'm running EH KT88 and I highly recommend them, although I have heard that the Tung-Sol 6550 reproductions have even better bass and more detail from another Simple SE builder (costing slightly more) and I may try them sometime. If I am not mistaken, Jim really likes the Genelex KT88 reproduction, though they are also slightly more expensive.
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