Rocket preamp tubes

[andrew]

What is your favorite preamp tube lineup on a Rocket?

[andrew]

Has anyone tried the Groove Tube "Mullard" copy 12ax7?

[RJ Guitars]

I know this has been talked about a bunch but my management of the search engine didn't find as much as I expected. I know I am missing it somewhere.

Please indulge me while I fly this flag again and see what we know or maybe somebody will point me to the the previous discussions.

What do folks think is the best new production preamp tube for a Rocket? I have some private reserve of old stock for myself but nothing to suggest for those that missed the easy days of tube scrounging and hoarding. I have heard some good things about the reproduction Mullards, Any thoughts?

rj

[KellyBass]

I've found I really like current production tung-sol 12ax7's.

And by the way, RJ...the saratov's you sent me for my latest rocket sound FANTASTIC! Thanks!!

[RJ Guitars]

Thanks Kelly,

As near as I can tell those Saratov's are the same tubes that Dr. Z is using in his Z-Wreck builds. I know the price of them sorta jumped in the past year as folks are catching on to them.

Below is a link to a good overview of the current production 12AX7's.

rj

http://thetubestore.com/12ax7review.html

[paulster]

I've found I really like current production tung-sol 12ax7's.

You need to be really careful of using the new Tung-Sols in cathode follower positions though as they can't tolerate the high cathode-to-heater voltages that we expect CF tubes to, and are way more prone to failing in this position than probably any new production tube.

They are a great sounding tube though for new production, just ill-suited for V2.

[Cliff Schecht]

I've found I really like current production tung-sol 12ax7's.

You need to be really careful of using the new Tung-Sols in cathode follower positions though as they can't tolerate the high cathode-to-heater voltages that we expect CF tubes to, and are way more prone to failing in this position than probably any new production tube.

They are a great sounding tube though for new production, just ill-suited for V2.

Is elevating the heaters to the power stage cathode enough to counteract this problem?

[paulster]

Cliff

The answer is I honestly don't know, as it's unclear (to me at least) what the maximum cathode-to-heater potential that these can reliably tolerate is.

Marshalls kill them in very short order, as do AC30s, which run at higher voltages across the preamp than the Rocket.

DC elevation to the power tube cathode voltage will reduce the potential but only by about 10V or so, so it's still debatable whether this and the lower preamp voltages is enough for long-term reliability or not.

It's a real shame about this element of the design because they're a really nice sounding tube as far as new production goes, but suffer this problem and also are prone to massive heater hum after a period (which I work around by using DC).

[KellyBass]

That's very good info, Paulster. I had plans for just such an CF arrangement on a future build and I'm sure I would have just grabbed one of the tung sol's not knowing this. Thanks! and it is a shame...I really like them.

[Structo]

Yeah the guys over at the Metro forum were complaining the new Tung Sol's didn't last long in the CF stage at all.

I haven't tried them yet but I am liking the quad of Tung Sol STR (6L6) that I have in my D clone.

[M Fowler]

I have been using JJ and GT gold.

[RJ Guitars]

I've found I really like current production tung-sol 12ax7's.

You need to be really careful of using the new Tung-Sols in cathode follower positions though as they can't tolerate the high cathode-to-heater voltages that we expect CF tubes to, and are way more prone to failing in this position than probably any new production tube.

They are a great sounding tube though for new production, just ill-suited for V2.

Thanks guys. Does anyone have a suggestion for V2 and can I assume that one of the new production Tungsols will work well at v3 as well as v1?

rj

[redshark]

Well, if you already decided to use new production tubes and have tungsol in V1 and V3 I would use either JJecc803 or a sovtek LP in V2.

[jelle]

Yes, use a IRF840.

JJ tall plate works for me so far. Also shuguang 12AX7's work for many people.

I only read about bad experiences with CF's and the New Sensor, sovjet tubes. Unfortunately they make a lot of different brand tubes.

[RJ Guitars]

I would like to be identify a good set of new production 12AX7 tubes that will serve to start up and tweak a fresh build amp build without breaking the bank.

I was reading up on Electro Harmonix and Svetlana offerings and the reviews were good but then I also read that these tubes are from the New Sensor factory and basically the same tube as the new issue Tungsol... so that doesn't sound like a good choice for a V2 CF candidate.

Does anybody know much about the Reissue Mullards? The review on these was also good but I'd like to add some real world credibility to go along with that review.

Otherwise it seems like the nod goes to the Sovtek 12AX7-LPS or the JJ.

Any other thoughts?

rj