4 replies to this topic

[david chau]

Hello All,

I am currently using standard china tubes in my KT88 amp (audiospace as2.8i), would it be possible to use kt120 tubes with a bias adjustment?

Would this be a good upgrade from KT88 and what improvements should i expect, if any?

Thank you.

DC

[ehtcom]

Hi DC.
Do you have any info/photos of your amp. All I can find on the net refers to the AS2.8i being a 6V6 amplifier.
KT88 tubes draw ~1.65 amp per tubes, KT120 draw up to 1.95 amp per tube. That is an extra 1.2 amps current draw on your heater supply.
Generally speaking (in my experience) less expensive Chinese amplifiers tend to fitted with power transformers that are just barely adequate, so I wouldn't recommend running them.
Also if your model is a 220v version and not a true 240v version, definitely don't. You will cook your power transformer.
BTW, (speaking from experience) the only way to confirm if yours is a 240 version, is to measure the voltages in your amp. Stickers are cheap

They have a similar tone to EL34's, if you don't need the full power available of the KT88 tubes you could try running some EL34 tubes to see if you like them. You will need to re-bias your amplifier when installing or swapping output tubes. Information on setting bias should be in your amplifiers manual.
May favorite new production EL34 type tube is the Electro-Harmonic 6CA7, it's a pretty faithful copy of the Philips ECG6CA7 fatboy (also branded as Sylvania), regarded as one of the best sound EL34 type tubes of all time.

Hope this helps. Cheers, Earle.

[Quark]

If you want to run with KT88 valves, I'd suggest SED Winged C KT88s as a good option. In my experience a huge improvement on the cheap chinese stuff.

[bronal]

If you want to run with KT88 valves, I'd suggest SED Winged C KT88s as a good option. In my experience a huge improvement on the cheap chinese stuff.

+1. IMHO the best current production KT88 at a reasonable price.

[Warren M.]

I have a JLTi KT88 Mk2 integrated amp, based on the YAQIN MC-100B amp (substantially modified by Joe Rasmussen of customanalogue.com), with 12AT7s replacing the 12AX7s, only 2 6SN7s from the original 4, and several very significant changes to the circuitry. I have been using KT120s in it almost from the beginning and I like them a lot. There is an effortless quality to the amplifier which I suspect is partially due to the considerable extra headroom offered by the KT120s. I've had no overheating or other power supply issues.

I have replaced the other tubes with esoteric tubes (Psvane 12AT7s and Sofia 6SN7s) but currently feel that the KT120s are a good balance of power and detail.

Regards
Warren