KT-88 vs. EL34


Hi. I have a modified Jolida 502 amp (not my main amp) currently using KT-88s and formerly the similar 6550s. Some have suggested that this unit will sound even better, power hit aside, modifying to accept EL-34s. The mod is easy. Anyone find this to be true or is it just another myth? Thanks in advance, Andy8400.

andy8400
You should be able to swap in 6L6 for EL34 as long as you can adjust the bias AND you get the GTB versions as they can work with higher plate voltages AND as long as your amp can work with these tubes in the first place. 

I have the newer 3502 model that takes EL34 as well as 6550 types.  Like someone said, one tube type is not necessarily better than the other, just different.  The amp does have more bass heft with the Svetlana 6550 than the new production EL34 and EH 6ca7 tubes I tried.  One exception is the JJ 6CA7.  This is a sweet tube!  Refined and warm with plenty of bass.
noromance, yes to both. My question was (is) what is the difference in bias voltage between the EL34 and the 6L6? I found some tube specs through Google and they look close in an AB final with the 6L6 about 90% of the EL34. The problem is, I'm not sure. I would hate to break the connection, but I can always fall back on inserting a milliammeter in series with the cathode and set the grid bias by the current recommended in the 6L6 tube spec. Or... pick a bias voltage below the point where the anodes (plates) start to turn red! Probably not the best idea but it actually could work(!).

sfall, I agree with you conceptually and, as mentioned, I bi-amped my system for some time but for bass control, not for more power. I could use the digital mode with four amps since the difference in sound from pure analog is virtually undetectable. However, I listen to mostly classical music and the complex harmonics from large orchestral music are detectable (barely, but subtly noticeable, nevertheless) when processed through the DSP. As said, I have subsequently maintained control through a graphic equalizer in lieu of bi-amplification.

That's why, getting back to my original OP question, I want to improve and possibly substitute my tube amp and get back to the basics of music enjoyment. Thanks for everyone's reply! Andy8400.


1graber2,

I too have a PLD HP. I have read many posting and Kevin Deal also speaks very positively about using KT150s

That's the tube I am rolling next.