You’ll burn up the power transformer in time. You will shorten its life.
ARC power transformers are very expensive.
Plate current 135 - 165 ma
Heater current 1.7 - 1.95 amp @6.3 Fil V
Plate current 150 - 180 ma
Heater current 1.75 - 2.00 amp @6.3 Fil V
samzx12 OPThe Ref110 was originally made by AR for 6550’s
I had an amp that I tried 6550’s, KT90’s KT120’s and KT150 in, it suited all.
But I found it sounded the very best using the Green Label plain white box mil spec GE 6550’s, this tube sounds way out in front of all the others for sound quality, btw the glass envelope was twice the thickness, you could tell when you ficked it with your finger nail, there was just a dead thud, instead of a ping!
Just like these > https://www.ebay.co.uk/itm/202717315969
For several years I had auto-bias integrated and power amps and I went through all the power tubes (and several small pre tubes). I ran El34, kt77, kt120, kt150, Kt88, 6550. I kept coming back to the El34s and the 6550s. At the time I had a pair of Spendor sp2/3s that the Sovtek 6550s sounded wonderful with. The Sovteks were new production and reasonably priced.
Please take into account that if one uses tubes specifically not recommended by the manufacturer, you are doing so at your own risk. I own REF 250 (not SE) amps and spoke with my dealer and with Audio Research representatives at the company about using KT150 tubes and they told me that several expensive upgrades must be done to properly allow for this use.
Expensive transformer life may be shortened. I'm good with the KT120s.
If, I decide to upgrade the amps to REF 250SE amps, then Audio Research will perform the upgrade, which includes the addition of KT150 tubes.
I've already spend a few thousand on repairs of one of my amps, simply because one of the tubes blew spectacularly. It took out some caps and resistors and an integrated circuit also. I was trying to save money and purchased "matched" tubes from a well known tube supplier.
The authorized Audio Research repair facility told me that they never uses tubes from that supplier as they aren't spec'd to Audio Research standards.
Anyway, unless you are prepared to come out of pocket for expensive repairs down the road, I wouldn't use tubes that the company doesn't approve of.
Thank you Minorl. Very informative and exactly what I was wanting to hear. I would never use tubes not recommended by the manufacturer. I'm really not into taking unnecessary chances with expensive equipment as some people evidently are as I saw a Ref 110 for sale with KT150s. I thought maybe they know something I do not or taking chances. Let's go with the latter lol.
My KT120s came from Upscale Audio and they were already in the amp when I bought it. They have approximately 300 hours and sound very nice. In another amp I despised the midrange of the 120 but in the Ref 110 much better.
@samzx12 - I had a Primaluna Dialogue Premium power amp at the time and the 120s sounded too zippy, the top end was a little over emphasized. Originally I had a quad of SED winged C 6550s that I really loved, very balanced, easy to listen to, relaxed but detailed. When it came time to replace them they were considered NOS and no longer in production so I got the Sovtek 6550s and was very pleased. All of the tubes were bought from Kevin at Upscale. The Sovteks had enough of that SED sound to make me happy. After rolling through all those tubes over the years I just felt, from my experience, that Sovtek was overlooked. Of course we all know everyones ears, systems, and rooms are different! Hope this helps!