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Old 22nd December 2006, 08:26 PM   #1
rdr is offline rdr  United States
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Default Sovtec 12AX7

I am returning the Sovtec 12AX7LPS tubes I just got from Parts Express for my Dyna PAS3 Pre amp. All four are very noisy. The power supply voltages are regulated and correct. The amp is MUCH quieter with the old Mullards they would have replaced. Anyone have experience with getting noisy tubes? Or know how this might happen? Bad batch? Or what?
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Old 22nd December 2006, 08:49 PM   #2
Glowbug is offline Glowbug  United States
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I auditioned a USAmps AX-TU300C with Sovtek 'LPS's in it, and I was not impressed at all. Then again, I'm not really a fan of 12AX7s in the first place, too much gain unless you're dealing with a guitar amp
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Old 22nd December 2006, 11:01 PM   #3
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Default Re: Sovtec 12AX7

Quote:
Originally posted by rdr
I am returning the Sovtec 12AX7LPS tubes I just got from Parts Express for my Dyna PAS3 Pre amp. All four are very noisy. The power supply voltages are regulated and correct. The amp is MUCH quieter with the old Mullards they would have replaced. Anyone have experience with getting noisy tubes? Or know how this might happen? Bad batch? Or what?

The 12AX7LPS is a QUIET tube. I wouldn't be surprised if P/E was selling other folks' rejects.

Buy your tubes from a reputable dealer, like Jim McShane. You'll get tubes that have been screened for noise and microphonics. Also, a proper burn in to cull out "infant mortals" gets done.
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Old 22nd December 2006, 11:40 PM   #4
Trout is offline Trout  United States
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"IF" you can find a 12AX7LPS they sound fairly good.

Personally, I will never buy anything that has been handled by New Sensor ever again.

They are the sole reason these garbage tubes are here in the USA. They were known to be bad, and should have never left the plant.

I have a dozen(ACTUALLY 14) that are brand new out of the box terribly microphonic. I have a 1/2 dozen defective 5Y3's, All internally cracked out of the box new. I have 9 EH 6V6GT's, 7 12AX7EH's
All bad and several came shorted at no extra cost!!

I do not care how reputable anyone dealer claims to be, There are lots of great dealers, every forum has their favorites,Thats not the issue,
The issue that New Sensor continues to distribute GARBAGE and lets the" DEALERS" here do the dirty work of weeding out the few good ones from the pile.

Send them back, and they just get recirculated or should I say re-cycled just like the Mullard and Tung-Sol Names!

I was offered a official dealer deal on bulk buys from New Sensor a couple months back, They actually called me and made it sound like I would be getting the deal of the decade, But if you figure in the 40% reject rate, You actually loose money.

OK, I ranted a bit, But the facts are there. They have terrible QC.

Trout
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Old 23rd December 2006, 12:16 AM   #5
rdr is offline rdr  United States
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Thanks. Based on this I will ask for a credit and not a replacement from PE. I picked up another PAS3 at a garage sale for $10 and I'm looking at the Van Alistine upgrade, which comes with tubes. Anyone familiar with this upgrade?
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Old 23rd December 2006, 12:21 AM   #6
kevinkr is offline kevinkr  United States
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Funny, this really hasn't been my experience with new sensor at all, and I've never had a problem returning the occasional defective tube. I will admit however that the volumes of Sovtek tubes I have bought recently has been quite small, I 'm much more focused on NOS and UOS these days since I no longer have to meet a price point on commercial sales and am focused only on my personal needs.

The 12AX7LP and LPS I bought in the past were always just fine, not noisy and no unusual reject rate. I have not bought any since the troubles started at New Sensor's Saratov (ExpoPul) plant though so I cannot vouch for the current quality level.

I have received more than a few 5AR4 that cracked over the years from various sources - the one common denominator was that they were all made by the same Chinese manufacturer. Current versions from several vendors seem fine.

I have had some problems with tubes from all "current" producers including Richardson here in the usa. (Cetron, etc.) (By "current" I mean ones that were produced relatively recently, the manufacturer in question may or may not currently be producing any tubes, or any tubes of a specific type. I don't keep that close a track on things.)

I have had pretty good luck with the JJ 12XX7 series of tubes and have bought significant quantities in recent times. These are the ones I would recommend of the currently available brands.

It would be wonderful if someone could pick up the ball and produce a really high quality version of some of the more commonly used types. Better QC is part of the ingredient too..

There is a good reason why we did not see Iron Curtain tubes frequently in the West prior to the cessation of production here and in Western Europe and that reason was that tubes earmarked for civilian uses in the Soviet block were often (not always) inferior to comparable types available from Western makers. There is not a strong tradition of QC outside of military production, and making the quota rather than quality was the more important consideration.
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Old 23rd December 2006, 12:24 AM   #7
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Default Re: Re: Sovtec 12AX7

Quote:
Originally posted by Eli Duttman



The 12AX7LPS is a QUIET tube. I wouldn't be surprised if P/E was selling other folks' rejects.

Buy your tubes from a reputable dealer, like Jim McShane. You'll get tubes that have been screened for noise and microphonics. Also, a proper burn in to cull out "infant mortals" gets done.


I second that..
I LOVE the LPS tubes I got from Jim,one of my Favorite 'AX7's now.
No noise,No hum,nada.

(PS: Hi Jim! )

Patrick.
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Old 23rd December 2006, 12:46 AM   #8
kevinkr is offline kevinkr  United States
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While I would not buy tubes from PE because I think there are better/more experienced dealers to purchase them from I think implying that PE is not reputable is a little unfair. I have bought lots of speaker components and passives from them and NEVER had a problem.
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Old 23rd December 2006, 12:54 AM   #9
rdr is offline rdr  United States
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PE is completely reputable. I am sure they will accept the return. I have spoken with a rep. I have bought a lot of stuff from them and will continue to do so. No one here is implying that they are disreputable.
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Old 23rd December 2006, 01:19 AM   #10
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i have also had great luck with the LPS in HIFI and MI... and I have bought dozens. I usually pay a bit more to get them tested and hand picked... they are pretty cheap as it is, so it's worth the extra dough IMHO.
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