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EL34 vs. KT66 output tubes

I've had the recent opportunity to compare EL34 and KT66 output tubes in my AES sixpac monobloc amps (the amps come with the EL34's). I am surprised how much more I like the KT66's. Male vocals in particular seem to really reach out much more with the KT66's. Although bass might not be as deep as the EL34's, it has a warmer rounder feel. Is the KT66 known to be a warmer sounding tube? Does anyone have experience with both of these tubes?
smeyers
smeyers OP
181 posts
 
Yes, 'richer' is the correct word for what I am hearing. I little more forward as well. I like the bass with the KT66's; it seems a little rounder and fuller than with the EL34's, although maybe not quite as deep.
trelja
3,215 posts
 
Well, that's why they make vanilla AND chocolate.

Most people, me among them, prefer the EL34 over the KT66 (and 6L6/5881), but the important thing is that you have found YOUR best tube!
s23chang
615 posts
 
"Most people, me among them, prefer the EL34 over the KT66 (and 6L6/5881)"
Trelja, I wouldn't say most.
9 out 10 audiophiles I know around NYC prefer the KT66 ( none chinese nor Russian ) over the EL34 ( all types )
Amp has a lot more to do with the tube.
Maybe most of the EL34 amps I've heard are less musical to our ears than the KT66/7027/6L6GC type of amps.
The only exception to our ears is the Vintage Marantz 9 PP amp from the 60s. That's the only EL34 amps we really like. Powerful yet musical ( except for the price tag.)
However, we did easily find many other KT66/7027/6L6GC and EL84 amps ( use it on higher efficiency speakers ) that sounded much better than the rest of the EL34 amps.

One should focus on the amp design and not the tube choice.
smeyers OP
181 posts
 
Trelja, I'm curious as to why you and others prefer the EL34 over the KT66. What are the characteristics of the EL34 that you prefer.

Chang, you mentioned a couple of times about not using the Chinese or Russian KT66's. Which brands to you recommend? Are there really good KT66's around that are not astronomically priced (I need 12 tubes)? What are the sound quality differences over the Chinese or Russian versions?
s23chang
615 posts
 
For Push and Pull application,
I got great results replacing KT66s with NOS 7027A for my application.
The 6L6GCs lacks control in lower frequency when compared to 7027A. Some might like the rounder and fuzzier sound of the famous black plate 6L6GCs.
The Russian and Chinese KT66s sounded even worst than the NOS 6L6GCs. A bit harsh which cause long term listening fatigue.
I don't really hear much difference between the RCA/GE/Sylvania tall/short bottle 7027As. Some of my buddies thought the RCA/GE sounded slightly warmer then Sylvania but we can't tell the difference during blind test.
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