2. amps-preamps
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KT120 back to 6550

Seen a ton of threads praising the KT120 over the 6550 or KT88. I get the new tube's durability and design but given that your amp was originally designed around one of the older tubes has anybody gone back.

I recently purchased and ARC Ref 110 that came with a set of KT120s. The output tubes test and match well so they don't seem to be at the end of their life (same for the signal tubes). 

This was a change from a VT100 equipped with 6550s. The VT100 had good midrange but seemed a little lean otherwise. Percussion was fantastic and voices just right. Just deep bass a little thin. The REF 110 definitely fills in the deep bass but seem a little congested in the midrange. Both top and bottom are an improvement.

Both these amps were sandwiched between an LS25Mk1 and a pair of JBL 4430s. Could be a synergy thing, these speakers work very well with high power solid state (Adcom GFA 5802). I've been trying to work up a good tube amp for these but so far I'm not feeling the love.

So the question is could it just be this system would work better with 6550s instead of KT120s?

Thanks
monoogan

Showing 3 responses by lalitk

lalitk's avatar
lalitk
5,634 posts
 
I have been on fence with tube rolling in my ARC VT-80. With its versatility with different types of output tubes, including 6550, KT88, KT90, KT120 or KT150, I just can’t decide which one’s to try.

One thing worth pointing out, I am using VT-80 for my mid’s and high’s only in a bi-amp setup. The LF’s are being fed through ATI 543NC Class D amp. As is, everything sounds pretty amazing. I am using LS28 pre and speakers are B&W 800D2’s.

@saki70,
@twoleftears,

After reading your comments, I am now anxious to try Genelex Gold Lion KT-88’s over T-S KT150’s. What do you guys think?

http://audioresearch.com/en-us/products/power-amplifiers/vt80


lalitk's avatar
lalitk
5,634 posts
 
@monoogan, 

Good point, it’s only 4 tubes :-) 

I think I should try the Gold Lion KT-88’s since I am already familiar with the T-S sound of KT-120’s. Granted, KT-150 has more power and might be slightly more extended overall. 

Thanks!
lalitk's avatar
lalitk
5,634 posts
 
@daveyf,

The VT80 was originally designed with the KT120, the predecessor to the KT150, but these two tubes are electrically interchangeable and the demand for delivering the VT80 with the KT150 could not be ignored. So ARC decided to introduce VT-80 with KT-150 tubes and dubbed the amp as SE version.
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