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?
rdr said:
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.
"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
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
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.
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.
Hi Jim! )
I'm not saying that P/E is dishonest. Obviously, that's not true. If you buy speaker drivers, cross over parts, and hardware from them you'll do FINE. However, I do think P/E has babes in the woods standing when it comes to tubes. They get stuff in from New Sensor or whomever and, in turn, ship it to customers. Problems like the 1 that got this thread started are the result.
Experienced tube dealers know to check the stuff they get in carefully. A damaged reputation is the kiss of death for a small business operator.
Experienced tube dealers know to check the stuff they get in carefully. A damaged reputation is the kiss of death for a small business operator.
This is very true, I have never bought tubes from Jim, Basically due to the quantities I have been buying, I look more for an OEM price structure.
I do not buy tubes to resell as a tube dealer would. These are part of an end product, just like transformers, fuses, and resistors.
This is where I take issue with Sovtek / New Sensor. You buy a bulk lot, and end up having to spend a week+ testing,sorting, rejecting and trying to return the bad ones which is like pulling your own teeth. There is a fairly short return time limit.
2 times I have ended up eating a 40% plus reject rate. Needless to say, this raises the price of the remaining good tubes to well over a reasonable cost.
I do not think it is entirely a QC issue. More so it is a policy issue. A bad run of tubes, or a batch with a high reject % should never leave the plant nor be exported.
I like the sound of many Sovtek tubes, But not enough to sort the very high percentage of rejects which I have had the luck to see recently.
Trout
An update. The Sovtec tubes are good after all. Seems the power supply in my PAS3 did not have enough omph and the plate voltages were too low. After I modified the regulator circuit I was using (zener regulated series power transistor) and added some extra filtering and mylar cap bypass the tube hiss went away. I did not realize that hiss was so dependent on plate voltage/current.
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