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kt66/el34/kt77 (kt77 in plexi?)

Discussion in 'Amps and Cabs' started by music321, Mar 10, 2015.

  1. music321

    music321 Member

    Oct 20, 2012
    Greater New York Area
    I've been considering the advantages/disadvantages of a plexi-type amp built to run kt66 instead of el34. First off, I know that to some degree this is splitting hairs. It's my understanding that the power section offers no difference unless the amp gets cooking pretty hot. If I'm going to get an amp built though, I want all of the parameters just the way I want them. Frankly, I can't decide on the kt66 vs el34 power section. It then occurred to me that the kt77 might be the answer since (as far as I know) it can be optimally run on a transformer selected for an el34. This means that if I don't like it, there will only be minor tweeks to put in an el34, rather than a different transformer.

    Now, as for the differences between the tubes. Performance wise, is the kt77 more like the el34 or the kt66? It's my understanding that it's essentially a kt66 but with more pronounced mids. Is this the case?

    I have seen the archived threads that address this, but I'm still not clear on the issue. Maybe this is because no one is really clear on it. I.e., the differences are so subtle b/t the kt66, el34, and kt77 that it's hard to pinpoint what the differences actually are. Someone says that the kt77 essentially sounds like the el34. maybe this same person would say the same about the kt66. I don't know.
  2. Polvo

    Polvo Supporting Member

    Apr 16, 2012
    Collinsville Il
    I like kt66's big glassy bottom end with chimey highs, never have used kt77s, I have kt88s in 71 SuperLead, they are huge sounding. but as far as running either or tube its just a bias resistor change, if it's set up for el34's I believe kt77s is just swap, bias go, and for 66's resistor change, bias and go.
  3. big mike

    big mike Administrator Staff Member

    Oct 31, 2003
    KT77 is (with any currently available tubes) like a bit EL34. More highs and lows, clearer mids. In most cases it will drop right in and bias up where a EL34 had been before.

    a KT66 is rounder, warmer and more 'high fidelity' sounding to my ear than an EL34/KT77 assuming all things are equal. I've run them all in a Reinhardt Vintage 50.

    Depending on the amp I like different things. a 6550/KT88 can be a nice compromise.

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