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Rolling 12AX7’s in my Phono pre…

MisterDK

MisterDK

Addicted Member
Hi folks!

I recently put together an ear 834 clone phono which uses three, 12AX7’s. It’s had some of the common mods done and other than some tube hiss with volume up, it’s sounding very good.


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This is the first thing I’ve built in a long, long time and my first tube amp, ever.
I noticed before putting the top on, that the NOS (Westinghouse, made in England) tubes in V1 and V2 seem very microphonic when very lightly tapping with a fingernail. I can’t help but think this may sound better with some new, modern tubes in it so I want to ask about a couple I’m considering.

As well as being quiet - these need to sound very good, too. I don’t want a quiet tube if it’ll sound flat and dry… I want rich and full - but not microphonic, and no hiss - if possible.

Here are tubes I’m considering; which if any, might offer what I’m wanting?

Sovtek - 12AX7LPS
JJ - ECC803S
Electro-Harmonix EHX 7025

Before suggesting something else that’s much more expensive - I can’t afford ‘em…
SO, which of the above may make me happy?

Thanks, Duane
 
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The Sovtek 12AX7LPS were initially very impressive; quiet, non-microphonic and they sounded good. I used them a lot in a very wide variety of equipment and applications.
Then they (most of them) started giving trouble; generally noise and outright failures. Then I started receiving complete duds. Noise, tubes with one section below cutoff etc.
Too bad, but I can't use unreliable tubes. Nor can I afford to keep replacing tubes that go bad in a totally unreasonable period of time.

Now I rely totally on the JJ 12AX7 variants. And have yet to have any trouble at all. Depending on application, either the ECC83S or the ECC803S.
 
It's always subjective, and every tube will sound a bit different in each different circuit. I used the old National 12AX7s made in Yugoslavia for years. When it came time to replace, I opted for the JJ - ECC803s....I liked them quite a bit, and found them clean and lively sounding, but within about a year I was wanting a bit lusher midrange. The Mullard new issue CV4004 has done the trick for me for the past 2 years....still really happy with them.

I have experimented with the Sovteks a while back, but don't recall liking them enough to leave them in the circuit...they got moved to my sons' guitar amps.

Love your preamp build!
 
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Try some silicone O rings to damp the tubes. Might shut them up quite nicely, and a bag will cost you less than a single tube.


The last tube in that circuit should be a cathode follower. You don't need anything fancy in that spot.
 
there is a chance to isolate the board from the chassis?
I still thinking is easy install the rings, gadget73 recommend.

Andre.
 
gadget73 said:
Try some silicone O rings to damp the tubes. Might shut them up quite nicely, and a bag will cost you less than a single tube.


The last tube in that circuit should be a cathode follower. You don't need anything fancy in that spot.
Click to expand...

Tube in V3 spot is a cheap Shugang and not microphonic in that spot. I’ll order a bag of O-rings to try.. :)

Andre Garcia said:
there is a chance to isolate the board from the chassis?
I still thinking is easy install the rings, gadget73 recommend.

Andre.
Click to expand...

PCBs are both mounted on nylon stand-off posts. Should they be rubber mounted?
 
Sounds like you have some nice tubes in there already. Don't worry about noise when you tap on them, listen to the amp. If it sounds good don't worry about the tubes, just don't tap them.
In my opinion the most important spot in your system for nice tubes is the phono preamp. Sounds like you probably have some old Mullards. I wouldn't swap them for JJs unless something sounded bad.
 
I have two EAR834 MM clones I bought.

One has (2) Sovtek 12AX7LPS & Genalex ECC83. A Jim McShane recommendation to me.

Other has (3) JJ E83CC, bought from The Tube Store. A friend recommended what he liked in a different phono. He only uses headphones. And is quite particular.

I can't tell you one sounds better than the other, IME.

I guess I would try those rings over the tubes. If the hiss is when above volume what you usually listen to. I would ignore it.
Tube power amplifiers can hiss with ear close to speakers. Not abnormal.
 
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Some Chinese 6N2's I had you could yell at and hear it through the speakers. Just touching the phono preamp came through the speakers loud. Using silicone o-rings did help some, but those tubes were junk.
 
Thanks guys.
Yeah the hiss I can hear is with volume up higher than my normal listening volume. I think I’ll put on some silicone O-rings and not worry about it. It really is sounding quite good..
 
Lavane said:
Some Chinese 6N2's I had you could yell at and hear it through the speakers. Just touching the phono preamp came through the speakers loud. Using silicone o-rings did help some, but those tubes were junk.
Click to expand...

Don’t think I’ll be buying those.. ;)
 
These clones do sound great. If you don't need adjustability.

If Dave is right. That you have Westinghouse rebadged Mullards. They are likely rich sounding.
 
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I recently replaced two 12ax7’s with NOS 5751’s in my CJ PV10. Bought em off the bay for a reasonable price.

I’m liking them!

Good luck! Mark
 
MisterDK said:
Tube in V3 spot is a cheap Shugang and not microphonic in that spot. I’ll order a bag of O-rings to try.. :)



PCBs are both mounted on nylon stand-off posts. Should they be rubber mounted?
Click to expand...
Better have them well isolated specially if the PSU share same chassis.
AG.
 
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