Emission Labs EML 30B-XLS tubes in VAC Ren. 70/70?

The VAC Renaissance amps are quite finnicky when it comes to 300-B's for a couple of different reasons.

First, any 300-B put in the amp must be made to the standard Western Electric 300-B specification. "Super" 300-B's that run higher plate voltages, such as the KR Audio 300BXLS, will burn up the amp.

Second, the VAC Ren's run 300B's hard -- 95% of the WeCo spec maximum voltage. This means that tubes like the vast majority of meshplates cannot be run in the Renaissance amps for the opposite reason - they can't handle the voltage.

I've owned VAC Renaissance amps for nine years and they require carefully vetted output tubes. Sophia Electric used to market a special set of the Sophia tubes for VAC Renaissance amps, which were the basic Sophia tube, but carefully tested at plate voltages that resemble the voltage that 300B's see in the Renaissance circuit. Generally, as for transconductance, 300B's for the Renaissance amps should test in the 3,000-5,000 range. In addition, the plate-to-cathode voltage for 300B's in the Renaissance amps is approximately 430 volts dc, with idle current approximately 85 to 90 milliamperes in a self-bias (cathode bias) circuit. Again, this is approximately 5% below the maximum rating for the WeCo spec 300B. The milliamp and transconductance testing for purposes of matching must be done at these voltage levels, or you will find out the hard way that your 300B's didn't make the cut.

Call Kevin Hayes at VAC and ask him whether this tube is a "super tube". From looking at the Emission Labs site, it is not entirely clear, but it is clear that it is not a standard WeCo spec 300B.

The Sophia Electric, Full Music and E.A.T. 300B's are premium tubes to run with the Renaissance amps, but they have to be carefully tested at the plate voltages they will see in the Renaisaance amps in order to ensure that they can handle the circuit.

I have the VAC Musicblocs which use the KT88. I'm currently using the Shuguang Penta Labs solid plate version. I have had my eye on those Shuguang Treasure Series. I look forward to your impression of the 300B-Z version.

Thank you for your responses – I already contacted Kevin at VAC but did not receive answer yet.
I decided to take another approach and ordered Shuguang Treasure 'Black Bottle' 300B-Z tubes from Grantfidelity (www.grantfidelity.com) in Canada.
This quite unusual tube (black bottle) is newly released and was tested on VAC Renaissance 140 amplifier.
I few weeks I will post a review of the tubes.

Best advice is above - call Kevin or Brent at VAC, instead of guessing. That's where I'd start.

I believe (not sure) that its actually the other way around. The 30B-XLS tube is NOT a drop in replacement for a 300B. I know for a fact that Cary says they are not acceptable in their 300b amps. I would check w Kevin Hayes or his tech. Quick phone call is all it takes and as expensive as 300bs are, the amp is WAY more $$.

Meta,

Interesting, I thought the Emission Labs could handle the stress the VAC put on 300B tubes. I know John L on Tubes asylum recommends the Svetlana 300B's but he states that unless you use a Variac to warm up your tubes, your failure rates will be high. I belive VAC uses Valve Art tubes. You should be OK using any of their tubes. I know the highly regarded TJ mesh plate tubes will not take the stress. Elecro Harmonix Gold grid tubes are supposed to be a great cheap alternative, Have not heard how they work in a VAC as yet. Sophia Electric Carbon plates are supposed to be THE tube. I contacted Sophia Electric and they stated that their Carbon Plates will work in a VAC amp but had an approximate 12% failure rate in the VAC amps. This coupled with the fact that they could not tell me the life expectancy of the tube dissuaded me. The other tube choice that intrigues me is the JJ 300B. Reviews on these are a mixed bag. It seems the SET guys say it is terrible, but the Push Pull guys say it is a fabulous tube. Vacuum tube Valley is very high on it. I dunno. I have seen several users of VAC amps use this tube. Western Electics are out of my price range due to the unavailability right now. Another intriguing tube is the Shuguang Treasure series 300B. very expensive at $600.00 a mathed pair. The Sovtek are supposed to be terrible as are the Richardson VAIC's. So sorry for the rambling, but I hope this info helps.