KT120 tubes in KT88 amp
Posted 03 August 2012 - 10:32 AM
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?
Posted 03 August 2012 - 10:52 AM
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.
"Don't cry because it's over, smile because it happened" ― Dr Seuss.
Posted 03 August 2012 - 06:45 PM
Posted 03 August 2012 - 07:29 PM
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.
Posted 04 August 2012 - 04:38 PM
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.
Vinyl: Once Analog + AudioOrigami PU7 + Shelter 501 (Soundsmith upgraded) + TTMega ring weight + JLTi-enhanced Eastern Electric MiniMax tube phono preamp
Digital Source: JLTi-enhanced (level 3) Oppo BDP-95 + Seagate 2TB drive
Tuner: Sansui TU-X701 / Burson Audio Buffer
Amp: JLTi KT-88 Mk2 (Tung-Sol KT-120, Psvane 12AT7_T & Sophia 6SN7 tubes)
Speakers: Totem Arro fronts + REL T2 sub.
Headphones: Sennheiser HD-650 (Cardas cable) & AKG-701
AV: Marantz SR5006 Receiver + Samsung UA55ES8000 Smart 3D TV + Wharfdale Diamond 9CM Centre + 8" Selby Ceiling Front Speakers + 6" Aaron Ceiling Sides/Rears + REL T2 Sub