Lower hiss V1's for Express

[jjman]

I already compared then selected the lowest hiss plate resistor for my Express type build for the 1st stage. It is a 3w flameproof MF. I would still like to reduce the hiss some more if possible by selecting a “low hiss” V1 tube. I’ve confirmed that all of this hiss is coming from that plate resistor’s path so the tube is next to experiment with. I have a new JJ in there but haven’t tried my others yet for hiss level.

Is there any consensus on which brands of 12ax7’s are higher and lower hiss in a typical V1 position? Is it a complete crap shoot for each individual tube? Do 12ax7’s generally hiss more as they age with use? Maybe a "good" 12ax7 should induce no hiss at all?

I understand there may be a trade off between tone and hiss if the quieter tube is not toneful. I’ll be trying a bunch of 12ax7’s from my other amps and I’ll post the results but if anyone has noticed any MFGr-based hiss tendencies I’d really like to know what you've found.

[Structo]

Although my knowledge is limited, isn't the his just part of a high gain amps design by proxy?
You're cramming a lot of electrons through there and they're gonna make some noise.

[Lonely Raven]

I tend to stick with the military tested tubes as they are made to be not only more robust, but be on the better side of being quiet.

CV4004
5751

I forgot what the other designations are.

Other then that, it's a crap shoot.

[jjman]

Well I went thru most of my stash and recorded the noise for each into a separate channel on my PC. My new JJ’s and EH did not do well and are now out of the amp. I first changed only V1 and found the new JJ was noisier than my 3 Ruby 7025STRs (Chinese) as well as my used 1971-74 RCAs and Japanese Harmony (labeled) one. I chose the quietest Ruby which I expect will sound great as they usually do. (These were a limited run sold by Lord Valve some time ago.) One of the Rubys was microphonic and got tossed.

I then moved on to V2 and the PI, recording with the volume turned all the way down. Again the JJ (PI) got replaced by a Ruby and the EH got replaced by an RCA 7025 from my 1971 SFDR. I haven’t used that tube since I bought the SFDR about 15 years ago. The change from EH to the used RCA in V2 also reduced the slight hum I was getting from stage 3.

I haven’t tested for tone yet but I’m optimistic that these will sound as good as or better than the 2 JJs and the EH that were in there. I have a used Mullard that did ok in the noise game so I may play thru that too. It’s normally in the SFDR.

I had assumed that buying brand new tubes was the best approach for the build. Probably should have splurged for NOS.

[CaseyJones]

+1 for NOS. The RCA 7025 is a good pick especially since you already own it.

You lose valuable gain with a 5751. Less gain in general means less noise and hiss more gain means more gain on everything including the noise floor. The trick is to lose the hiss, keep the gain.

In NOS: GEs are my go to low buck utility 12AX7 but not for Trainwrecks. All of mine tend to be noisier and more microphonic than my other choices. The GEs are great to wake up a vintage amp.

Sylvania. The audiophiles are catchin' on to the fact that Sylvanias are a good sounding low noise tube.

We already talked about RCA.

If you can stand the price Telefunken, Mullard and Amperex are great just about in that order. I've never hear complaints about "bad tone" from smooth plate Telefunkens, just lots of bitchin' about the price. Bugle Boys are inexpensive by comparison. Of course everyone should own at least one good shield logo Mullard just to see what they're missin'.

[Richie]

when you find a good tube for v1.. stick it in V2.. then try some tubes in V1 again.. its almost like a combination of the 2 positions..

If you have a crappy tube in v2..it will be harder to find or make one work in V1..

[lewilson]

I have theae in all 3 spots. There quite http://thetubestore.com/rsdecc83.html

[CaseyJones]

I have theae in all 3 spots.

Those RFTs look suspiciously similar to those Shwang-Wang Chinese 12AX7s that were available a couple years ago. I bought a hundred of the Chinese tubes for a buck each to use in customer's Blues Juniors and the like. Now that they're all gone it turns out they're pretty good tubes. Go figure!

Then again there are apparently 17 versions of the Chinese 12AX7s avbailable and I can't be bothered to keep track of 'em all. Long plate U.S. made NOS, that's easy... it's gotta be good!

[Structo]

I have theae in all 3 spots. There quite http://thetubestore.com/rsdecc83.html

Yes I have heard that the RFT's were kind of a little known tone tube.
But, alas, they are all gone. At least at that site.

[Lonely Raven]

I think blaren has some RFT tubes, but older ones then the ones linked above.

I'm not sure if his are NOS or pulls, but the one I got from him sounds pretty good!

[lewilson]

I see them on ebay once in a while.

[GitDiv]

Hi, everyone. First post here.

I was wondering if a 12BZ7 would work for V1.

Dave

[dartanion]

GE short plate 12AX7 is a good choice in V1. The lowest noise tube should be used in V1, so I would wager that the RCA 7025 will be your best bet there. Find another low noise good sounding tube for V2.

[Richie]

I was wondering if a 12BZ7 would work for V1

I tried a bunch of those 12BZ7 ,even in fender amps, and they were microphonic and hummed. You can try them if you want, but i never had much luck with any of them

[GitDiv]

Pardon my ignorance, but are the 12BA7's and 12BZ7's the same?

I stuck a Sylvania 12BZ7 in V1 on a VJ and it sounded a lot smoother than the JJ 12AX7 I had in there.

I want to do an Express build, but I'm still debating on what to include on it, and which version to try.

Dave