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Shuguang Treasure tubes....

I'm not sure if this is in the right place but this is about the tubes in my amp so here goes....Has anyone else given these Shuguan Treasure tubes a try?

I recently bought a used tube amp(VAC Phi 110) and the tubes that came with it were shot so I started poking around for some new tubes. I was looking for some Shuguang tubes, which are what I believe VAC supplies as standard/stock, and ran across Shuguangs limited production Treasure tubes. I poked around and did some reading, found a review or two and decided to give the only distributer for N. America(Grant Fidelity) a call. I spoke to a very kind and helpful lady who was patient with me(quite the task I might add!), was very nice and helpful and was darn knowledgeable on the tubes. Before I knew it my wallet had leapt out of my back pocket and I had splurged and ordered a matched quad of the Treasure Tubes, KT-88s. Within a couple of hours I had a tracking number and about a week later a box labeled "FRAGILE: GLASS!" was waiting for me when I got home from work.(A quick side note; during the short wait for the Treasure tubes to arrive I was using a borrowed quad of stock VAC KT-88 tubes and they were wonderful, great sounding tubes that I could live with forever....or that is until I found the Treasure tubes anyway.)

When the Treasure tubes showed up I ripped into the box and was shocked to see that each pair comes in a really nice presentation box with each tube very well protected in a foam insert, very classy. I removed the tubes, admired their beauty(they really are sweet looking tubes!) and popped them in the VAC and let them warm up for about 15-20 minutes. I then set bias on them and hit the play button expecting the usual tube break in time-wrong!...right out of the box these tubes sound fantastic! Seriously, I am shocked how at just good they sound fresh out of the box. Smooth clean highs, strong deep bass and all the other audiophile words we so endear. If they're this good right out of the box I can't wait until I get 100 hours or so on them. I'm no reviewer but I can say that these tubes offered a noticable improvement in my system and are worth every penny of their asking price, no doubt about it! So far they are chugging along and sounding beautiful and hold a rock solid bias, ZERO fluctuation.

Please understand that I have no affiliation with Grant Fidelity but when I run across a company that treats their customers so well and offers a product that performs at this level I feel I should share my experience with others, I'm one VERY hapy audionut!

Yes I actually do have a question and here it is; They(Grant Fidelity/Shuguang) also offer a 6SN7 substitute called the "CV-181", this is supposed to be a direct replacement for standard 6SN7's and I'm very interested in those as well. Has anyone else had the opportunity to give these tubes a try? Thanks for your replies.

Sincerely,
John
128x128johngp
grantfidelity's avatar
grantfidelity
21 posts
 
JohnP, there is a very positive (as in replaces his NOS favourites)review over on TNT-Audio for the CV-181's.

Cjfrbw, the very unfortunate thing about factory matching is that they think +/- 20% is fine for matching, which is the industry norm and as cool as their test gear is, the Amplitrex AT-1000 tester gives much more accurate and detailed results. We do have to rematch everything we recieve. Btw, NOS and other new production tubes also don't fair well in the Amplitrex for close 'Hi-end' matching. It can take many pairs to create a good pair and gets harder for quads etc. We hope our gear has at least 5% tolerance between parts in each channel, 2% being our specs and I've seen some guys go even lower to 1%, kind of doesn't make sense to throw in 20% tolerance tubes or worse eh !

Cheers,
Ian
jcspinks
17 posts
 
OK. 150 hours for the 6CA7s on the books and some very nice improvement in the vocals and treble. Now far smoother and outstanding imaging, very precise and fast, yet never in your face. Great resolution of detail now that was previously the opposite, somewhat slurred. I would say in each of these regards it (for now) surpasses the Siemens. Where the Siemens still excel is in the upper bass, where they do a better job of keeping the pace moving forward. Some of this is of course bias-dependent, but I'm pretty sure that the Siemens would win there now regardless of bias. Cymbals are still more real with the Siemens, but it is getting much closer.

These Shuggies are starting to impress me. Let's see if they can go all the way. I'll keep cooking them.
jcspinks
17 posts
 
200 hours in on the 6CA7s. Upon first listening after resetting bias to 34.8, the sound seemed very similar to the 150 hour mark with great vocals and detail, but with a minor lack of upper bass drive. Cymbals still a small tad less believable than with the Siemens. So, I decided to once again play with bias. I lowered it by one mA to 33.8 and got a shift to a tad more upper bass and cymbal realism with no destruction of image or vocals. Still looking for a bit more drive, I went ahead and lowered it by one more mA to 32.8, and by God I got it. It is responsive after all. However at this setting vocals started a bit of recession backward and imaging went softer. I reset to 33.5 and promptly got the best of both worlds, sounding very, very good indeed. The sound is now in competition with the Siemens.

I am still stunned by how these, like the Siemens, are SO responsive to smallish deltas in bias.

Perhaps this weekend I will reinstall the Siemens for a reality check. We all know how our audio memory is sometimes. However, I am pretty sure these are close and may even exceed the NOS tubes.
trelja
3,223 posts
 
This is your second great post in this thread!

We in the high-end audio crowd overlook the importance of bias in our tube amplifiers. Generally, the guitar amplifier crowd has a far deeper understanding of this parameter, and there are tuners build their business simply from the proper application of bias.

In actuality, bias is more important than the tube itself, as it is where the tube operates which determines the tone of the amplifier. Optimizing bias in one's amplifier is the key to getting the best sound.

This is not as simple or obvious as we hope as the characteristics of both tube and amplifier must be thorougly balanced. By this I mean that tubes of the same type from different manufacturers are more different than we may think. Likewise, it seems obvious the differences between amplifier A and amplifier B are often such that simply biasing an output tube to the same value (say -40 mV or whatever) would go against the grain of the manic tweaking and tinkering (cabling, isolation devices, room treatments, cryogenics, rolling tubes, etc.) of the high-end audio today, yet that is exactly what happens.

Hopefully, the new tubes work out for you in the end.
jcspinks
17 posts
 
Good points. I now wonder how much of changing sound due to selection of driver tubes (for me 6SN7s & 6SL7s) is that they also affect the power tube idle current (hence operating range) by tenths of of mAs. Previously I had not reset bias on the power tubes when rolling drivers. For these driver tubes with twin triodes, each power tube is tied to only one of the triodes in each tube for my amps' push-pull design. Any inequities in the triodes and any delta gain relative to the reference drivers seems to affect the measured current.

After the Shuggies reach equilibrium I will reexplore interactions with drivers and power tubes, checking both sonically and for associated changes in idle current.

Now at about 225 hours...
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