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AUDIO FORUMS >> Replacement Tubes >> Current tube compliments
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Message started by __Jon__ on 12/07/21 at 03:33:24

Title: Current tube compliments
Post by __Jon__ on 12/07/21 at 03:33:24

In the year or so since I ordered my first Decware amp, I've enjoyed reading everyone's posts regarding their tube rolling journeys. Many of these threads are now years or even a decade old, and I was wondering if people would be willing to share what tubes they are currently using in the various Decware products they own. I have a ZMA and am currently very deep on the waitlist for the beginnings of a second lower watt system. I can't help myself and want to plan ahead.

Best,

Jon

Title: Re: Current tube compliments
Post by __Jon__ on 12/07/21 at 05:48:04

I’m currently pleased with Phillips 7027as as power tubes and rotate signal tubes to compensate when I try different rectifiers in my DAC, currently some 60s amperex sq’s and some Mazda e188cc’s. I really like the Mazda’s. A little more sparkle than with the amperex, but similar. I would like to try some of the new issue genelex kt77s and kt88s one day. Ive tried most of the other power tubes mentioned in the forums and prefer the 7027a’s. The new production Tung Sol versions were surprisingly good, although I felt not as good. It seems like I bought the last 10 Phillips versions (8 matched and 2 spares) on the planet so will have to find something else eventually.

Our current ZMA system is in a small to moderate sized combined office / art / music space. I am planning a second system using larger more efficient speakers in a larger space. So far I’m very far down on the waitlist for two SE84UFO25s and a CSP325 and am figuring out then rest.

Title: Re: Current tube compliments
Post by Archie on 12/07/21 at 06:21:09

I can't imagine buying NOS or used 7027As since they are always so expensive when I see them. The Tung-Sol 7027As are lasting under a year in my ZMA. How are the Philips holding up for you?

Title: Re: Current tube compliments
Post by HockessinKid on 12/07/21 at 12:55:21

Jon,

Most ZMA owners posting on this forum have noted positive results with new production KT-66, 7581, 7027A and KT-77 power tubes. Given a 2000-2500 hour lifespan of power tubes and the high cost of NOS tubes, most of us have opted for new production tube quads as replacements in the ZMA.

Given our different system builds and more importantly listening room conditions it can be a toss up as to which will sound best, let your ears be the judge. With new production tubes costing $100-$200/matched quartet you can experiment to some degree without breaking the bank.

New Sensor produces rebranded TungSol, Gold Lion, Mullard, and Sovtek tubes and these are readily available from online sellers. I have enjoyed Gold Lion KT-66 and KT-77 tubes, along with TungSol 7581 and 7027A's. Also the Tube Amp Doctor 7027A's. Each tube has different attributes, so my suggestion is to try a couple sets for +100 hours and listen for what sounds best in your system.

HK

Title: Re: Current tube compliments
Post by __Jon__ on 12/07/21 at 16:21:38

The Phillips still seem as new. I haven’t had to touch the bias, currently at 60. I’ve kept it lower than some, thinking about tube life. I’ve been using my amp for less than a year though. Probably averaging 2 hours 3-4 times per week. Sometimes more but I have an active family and am also busy with work and other projects. I’m not going to buy any more NOS power tubes until I get a handle on how long they will last in my system. I picked up a set of the TAD 7027a’s recently but haven’t had a chance to try them yet.

Title: Re: Current tube compliments
Post by Archie on 12/07/21 at 17:08:27

Jon, I do push my 7027As harder biasing closer to 68mA. I'm probably just wearing them out since I really don't hear a difference when biasing lower. I'm biasing my Tung-Sol 7851As at 56mA though. They won't bias as high as the 7027A anyway.

Title: Re: Current tube compliments
Post by __Jon__ on 12/22/21 at 00:02:24

Was wondering if it is ok to substitute 0c2 (or equivalent) tubes for the 0a3 tubes in the ZMA? They seem similar electrically in terms of voltage and current. I had planned to try but figured I would run it past folks in case it’s a bad idea. Thanks.

Title: Re: Current tube compliments
Post by Lon on 12/22/21 at 05:44:36

0C2 would not, I believe, work, quite a different tube. It's possible that 0C3, 0B3 and 0D3 might work--they do in my SE84UFO3 Monoblocks and the Torii Mk III that I used to have--but they aren't mentioned in the manual for the ZMA. I would wait until a ZMA owner responds. . . .

Title: Re: Current tube compliments
Post by __Jon__ on 12/22/21 at 06:38:23

Thanks for responding Lon.

I’ve read that the 0b3, 0c3, 0d3 tubes are for sure off limits for the ZMA previously somewhere in the forum.

I was reading elsewhere recently and had noticed that the 0c2 tube is 72 volts 5-30 mA vs 75 volts 5-40 mA for the Oa3. Thought it seemed close and I enjoy trying different things when it can be done safely. :) Not even sure in the pinout / bases between the tubes are the same though.

Just figured I would ask. Maybe someone will have looked into this before.

Cheers,

Jon

Title: Re: Current tube compliments
Post by Lon on 12/22/21 at 12:10:28

Jon, an 0C2 is a 7 pin small tube, the 0A3 (and 0B3,0C3,0D3) are larger 8 pin tubes. An 0C2 just won't work in the ZMA. An 0C3 would fit in the amp, but I'm not sure it will be a good choice--ZMA owners or Steve would need to weigh in--I have never owned or heard a ZMA myself. The manual does not mention any substitutions.

(Edited: thanks CA)

Title: Re: Current tube compliments
Post by CAJames on 12/22/21 at 15:38:00

OC2 is actually a (miniature) 7 pin tube. To my reading it is similar to an 0A3 electrically but good luck finding an adapter.

Title: Re: Current tube compliments
Post by __Jon__ on 12/22/21 at 17:27:31

Ok, thanks. Doesn’t seem worth pursuing.