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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 I just had them serviced but one of the cheap Svetlanas blew, probably from my biasing it too high, and its been replaced by a used Genalex Gold Lion for the moment.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
bradf's avatar
bradf
288 posts
 
This doesn't really answer your question regarding best KT 88, but I thought you may find some interest in it. I too am considering replacement of power tubes in both my Ars Sonus Filarmonia, and Primaluna P5.
I have been researching Psvane EL34, and KT 120 (including Black treasures)
I have a spare set of JJ E34L quad for my Filarmonia that I substituted for the Gold Lion KT88 in My Primaluna 5.
A truly unbelievable improvement. It is the most difference / improvement I have ever experienced in a power tube and I have tried a number Including the GL KT 77 and NOS GE 6550. I am pretty surprised how well this $14.00 US dollar sounds. You may give it a try. There available at The Tube Depot in quads and for a couple bucks a piece you can get them burned-in. Just want to clarify that these are the E34L's and not the EL34's. Also came across a couple of vendors selling NOS Siemens EL34 https://www.tubedepot.com/products/rft-made-siemens-el34
http://www.tubeaudiostore.com/elpremgrad.html.
http://www.nosvacuumtubes.net/product-category/power-tubes/power-tubes-6550/
The above 3 links/stores have several type of NOS power tubes, including NOS Mullard EL34 (expensive) and Amperex EL34, and others
You may find the new production Telefunkene Black Diamond EL34 tubes of interest. In addition to EL34's they are also producing 6550's and KT88's.
With the exception of the JJ E34L tube, I can't help you regarding the sound of the above referenced NOS tubes, that's something I am trying to gather info on.
Any one reading this, who has tried any of the above NOS tubes or the new production Telefunkene Black Diamond tubes your input would be helpful. 
xti16
1,495 posts
 
If you’re considering KT90’s look for the Ei KT90 Type II. They don’t come up often but when they do they are a bargain IMO. Tough as nails with mids similar to El34’s but with more sparkly highs and tighter lows. I found the sound stage improved by getting wider.

As far as KT88’s I have the winged ’C’ SED KT88’s and they have a lot more bass than either the Ei KT 90 or Gold Lion (Russian reissue) KT88’s (which I also have). The original Gec KT88’s are very linear sounding. Extremely good and almost as good as the EAT KT88’s. But those come with a hefty window sticker.

That said I had an Octave V70se and later a V110. A lot will depend on the topology of your amp. More important IMO is the speakers. If you’re looking for a warmer sound the SED or GL KT88 is the ticket. If you’re looking for more detail and linear the Gec or EAT KT88 is the direction you want to go. Never tried any of the Svetlana or Shuguang tubes. Personally I hated the KT120's. To me they never sounded coherent like any of the tubes I have.
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Ah, so you are not looking for different KT88's, you are looking for a different amplifier.
In this hobby, there are many different tastes. Obviously you have a sweet tooth. Nothing wrong with that. You are right, you won't get much sweeter sound from a VAC than using the Mullard CV4003 driver tubes. VAC is not really a tube amp designed to sound sweet. They have a bit more air and refinement than the ARC house sound, but overall VAC is still on the high resolution side of the fence in the tube world.

If you are looking for old fashioned sweetness in a tube amp, you would probably be happier using one designed with EL34 tubes as jond suggests, or an amp from conrad johnson or Cary.
wolf_garcia
4,650 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. 
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