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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 I just had them serviced but one of the cheap Svetlanas blew, probably from my biasing it too high, and its been replaced by a used Genalex Gold Lion for the moment.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

Showing 11 responses by andreweast

andreweast OP
30 posts
 
I should have said 'for reasonable money'. The prices for NOS GEC KT88 are absolutely crazy now, if you can find them! So they're out of the question.

Black Treasures are appealing, but some things I've read suggest that the Psvane KT88 T2 will be more tight and controlled than the BT as well as having more body than the Gold Lions. However I can only think of one internet post that has compared them in detail so there's not much to go on.
andreweast OP
30 posts
 
Thanks, so did you find the Psvane only marginally better than the Gold Lions? There seem to be several varieties of Psvane now, including the cheaper KT88 UK, which are meant to have a slightly warmer 'classic British' sound. They are also less expensive. The KT88 T2 are the priciest, more expensive than Shuguang Treasures. 

maxmad, thanks for that link. They don't seem to have much in at the moment, but I'll keep a look out.
andreweast OP
30 posts
 
I think a more concise acronym would be GITS (Garcia Issues from Tubes Study). I'd be happy to take part in the experiment, but only if I get a confirmation from Kevin Hayes that it is safe to use the new uber-tubes in the Auricles. I've fired off an email.

I don't need anything like the enormous power of KT150s with my 93dB speakers and small room, but KT90s might be a good choice. A friend of mine uses the EH KT90s in his VTL 150 and that sounds great. 
andreweast OP
30 posts
 
Kevin has just told me that the Gold Lions might be the best idea to get what I'm looking for, and that is certainly the easiest option for me.

I take your point that the input valves are likely to make more difference, but I can't get much warmer than my Mullard CV4003. Pre-amp valves I can work on.

I suspect the change I'm looking for may not come with small things like valve changes, I've just switched speakers from my Vaughn Cabernet 1 to my Harbeth SHL5Plus. There's certainly no lack of warmth with the Harbeths, as you'd expect. It might be that I will need a differnet power amp to get a warmer and more intimate sound with the Vaughns, but then I'd risk losing the amazing dynamics. Always a tricky balancing act. 


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. 
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.
andreweast OP
30 posts
 
I'd love to try 300B with the Vaughans. I'm sure you're right that its the big trannies that matter, but it seems that is what you pay for. 

The Unison Research S2 had no bass control, so that was out of the question. But I tend to like the UR sound (I used the Unico Pre/DM for years) so I would like to hear one of their higher models.


andreweast OP
30 posts
 
wrm57; thanks for that very useful information. I'll see if my friend can pick up some of the Preferrred Series. He just told me that this shop in Kyoto has Shuguang. It's apparently a very messy little shop full of tubes, with a couple of shabbily dressed guys. Sounds dodgy, but charming! I suspect they will be the cheaper KT88-98 though. Have you tried those?
andreweast OP
30 posts
 
I have some breaking news, which is that the Auricles should be ok with KT120s. Very tempted to give them a go.

andreweast OP
30 posts
 
That's interesting Sherod, thanks. Do you have a VAC pre-amp also. The only reservation I have about the Auricles is that they are extremly insensitive at 1.5V and need lots of gain. I suspect they are made for pre-amps with gain of 20dB or more. Even with my ARC LS26 I don't feel I've got that much headroom. However I don't need high volumes so it's not really an issue. 

So, I bought some KT120. It's almost like I've got a completely different amp to when I was using the Svetlana KT88s (although admittedly they were not a matched quad, one of them had blown, and I'd replaced it with an aged Genelex).

The KT120 have a much warmer sound. So much so that I've switched back from Mullard to Philips driver tubes. Previously I thought these amps might be too lean and clinical for me, but now it's almost gone the other way. Very good, but I still wonder if there might be an option somewhere in the middle.

I do have an option on some discounted Shuguangs, which are apparently selected examples that a dealer has had since the 90s. Tempting to compare them, but I've just spent money on the KT120s, so I'll see if the sound opens up any more first.
andreweast OP
30 posts
 
Tweaking is what I'm doing now. And I have to take back what I said about KT-120s since I switched to the 8 Ohm tap. Now they are neutral and dynamic rather than warm. I think the previous tubes I was using sounded too harsh and forward on the 8Ohm so I was forced to use the 4 Ohm tap. My speakers hardly drop below 8 Ohm so I guess this was overworking the amps. 

I actually want a bit of warmth back now! Oh for a 6 Ohm tap. I'll try chanigng back to Mullard driver tubes. 
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