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Best KT88s (specifically for VAC Auricle Musiblocs)

I'm using a KT88 based amp for the first time - the VAC Auricle Musicblocs. I just had them serviced but one of the cheap Svetlanas blew, probably from my biasing it too high, and its been replaced by a used Genalex Gold Lion for the moment. The amps sound very good as it is, but I'd like to get the best out of them with a good matched Quad of something decent.

Ideally I would like a little more mid-range luxury and presence without sacrificing too much bass control. However lower bass is not so much of an issue because my speakers have powered subs with an active crossover (Vaughan Cabernet One).

I'm in the UK, and valve selection here is a bit limited. Nobody seems to have Svetlana Winged Cs anymore, and I've read reports of dubious quality in the later batches. Genelex Gold Lion are easy to get from good dealers who can match and measure, so that is the obvious choice. But would I be better of with some Chinese valves such as the Shuguang KT88-98? Are they going to be a bit warmer in sound to the Genelex?

I've read great reports about the Psvane KT88 T2 but they are very expensive. Also the Shuguang Treasures. The riskiest option is to buy these from Mable Audio in China, who have them up for a good price:

http://www.mableaudio.com/en/

From what I have read Kevin Hayes supplied the Auricles with the Shuguang KT88-98. These are very affordable, but I suspect that Kevin only supplies selected ones. 

I could also buy from the US, and I'd appreciate any recommendations for the best source.


andreweast
wolf_garcia
6,628 posts
 
KT150s won't increase the power of your amp substantially unless it's designed for more power. My modest (I keep saying that to remind people how thrifty I am) 6550/KT88 specified Jolida 502p simply "sounds" better with 120s (which sounded splendid during 3 years or so of heavy use) and even better than that with 150s, and neither of these tubes has caused transformer overload or anything other than tighter, more concise full range tone (I have 6550s and KT88s in my reserve tube stash so I've compared these things).  Don't fear the 150…it's shaped like a pickle...
andreweast OP
30 posts
 
I take the point that I might be better off with an EL34 based amplifier. I could go much lower power than that. I've got a 2A3 based integrated which powers the Vaughans well. If there is a tube I have a natural liking for its the EL84, but I don't think 4 would be enough, so I'd have to go for an amp that used 4 per side and that is getting more pricey with tubes. 

I actually realised that what I'm missing is not mid-range warmth, it's mid-bass. I switched in my Croft amp for the VACs and whilst it doesn't  have the same level of vivid clarity in the mid-range and exceptional resolution as the VACs, it has an all round warmth and ease.

 It was clear that what I'm missing with the KT88 based amp is the mid-bass. The question is whether this is the amp, the KT88s I have, or whether it's the nature of KT88's to lack some warmth in that area in comparison to EL34s.

A friend of mine is in Japan at the moment and could pick me up some Shuguang KT88s for the same price as importing from China. I just don't know if it will quite bring the change I'm looking for. 
maxmad
182 posts
 
In my opinion, KT88 is much better tube than EL34 and I simply dont understand why people buy USD 5000-10000 amps and put shity tubes in it, all beyond me. From many things I learn in this hobby there is one simple, bigger bottle>bigger sound, I compared KT88 to EL34 and 6550 and they eat both tubes for breakfast and I had most wanted Philips EL34, NOS Tesla EL34 and Tung Sols 6550 smoth plates and GEC KT88 won just like that. For me, stepping from KT88 to EL34 is stepping down, only to 300B would be my choice and thats what I did, but thats another story.
andreweast OP
30 posts
 
maxmad, did you compare in the same amp? And what kind of speaker efficiency? 

Surely it will all be relative; with 86dB speakers you are going to want a KT88 based amp if you are using valves; with 106dB horns you are going to want 300B. And with my 93dB speakers ... well, I'm in between all these possibilities. 

A friend brought round his Unison Research S2K a couple of weeks ago. A budget SET amp but a very nice design. He had a pair of 6550s in and the sound was extremely immersive, a great sense of space filed with micro-detail. It had a wonderful way of getting the inner detail of a saxophone (the close focus on Coltrane's vibrato was new to me). But central voices tended to be lost a little behind the whole soundscape. Then we switched in a couple of my KT88s. Suddenly the voices were central and clear, but all that lovely spatial immersion and the inner detail was lost. I don't know if that is a comment on my particular KT88s, or how that amp works. It was supposedly designed for KT88s, but we were clearly missing something when we took out the 6550s.
wrm57
982 posts
 
I tried the Gold Lion KT-88s in my 300.1a and did not like them at all--very detailed but too mechanical and hard. The Shugang KT-88SC are much better to my ears, with more bloom and texture along with plenty of detail. But VAC can no longer source them, so they've shifted to the GL. 

Fortunately, after a long search, I found KT-88SC at The Tube Store, labeled as their "Preferred Series."  After six months of steady use, thet have proven far more reliable than the ones VAC was selling toward the end of their supply (I had 4 tubes out of 8 new ones from VAC blow within 6months of light use). Much less expensive than the VAC SC, too.

I like these tubes so much I bought six matched quads. Meanwhile, the GLs (2 matched quads from Jim McShane) sit in a drawer with all of 50 hours on them, unlikely ever to be used. Of course, YMMV.
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