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Old 24th October 2010, 06:33 PM   #31
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Originally Posted by analog_sa View Post
From where? I have stopped trusting most US sources for these tubes. There seem to be too many rejects on the market. Getting tubes from any of the ex - Soviet Union countries seems much safer.
U.S... tubedepot.com

I don't know of any ex-USSR tube seller. Who they might be?
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Old 24th October 2010, 06:35 PM   #32
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in THAT case - contact ARC

have you any possibility to directly compare your LS25 with anyone else's , or do you have ARC dealer near you ?
I don't know anyone personally to do a swap test. I've only heard from owners of this preamp that it is dead quiet in their setup.

I'll get to the bottom of this sooner or later. I will contact ARC this coming week. Thanks for your help.
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Old 24th October 2010, 07:38 PM   #33
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Originally Posted by GeneJazz View Post
U.S... tubedepot.com

I don't know of any ex-USSR tube seller. Who they might be?
Ebay.

I may be a bit paranoid but what do you think happens to all those tubes which do not meet the matching/noise/microphony requirements of ARC and BAT? I doubt they crush them with hammers. The tubes i bought from Parts Connexion were 80% duds. Sent them back and from the matched replacements they sent only half were duds. Some worked normally for a while at very modest dissipation and then developed problems. The ones from Russian Ebay sellers were slightly more expensive but absolutely perfect.
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Old 24th October 2010, 09:28 PM   #34
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Originally Posted by analog_sa View Post
Ebay.

I may be a bit paranoid but what do you think happens to all those tubes which do not meet the matching/noise/microphony requirements of ARC and BAT? I doubt they crush them with hammers. The tubes i bought from Parts Connexion were 80% duds. Sent them back and from the matched replacements they sent only half were duds. Some worked normally for a while at very modest dissipation and then developed problems. The ones from Russian Ebay sellers were slightly more expensive but absolutely perfect.


This might make me run back to solid state... 80% failure rate? c'mon.

ARC LS3 is looking quite good now. I don't mind tweaking and fussing over things but if the tubes are that prone to misfire, I think I'll pass.

I'll check Ebay... sigh....
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Old 24th October 2010, 10:26 PM   #35
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You have certainly misread me. I wasn't talking of tubes in general but merely of the leftover 6H30 offered to diyers. I have hundreds, if not thousands of other tubes, mostly NOS and failure rates are indeed very low. It could certainly be a bad batch, but rejects make a lot more sense. The tubes supplied by ARC should be first rate and work for tens of thousands of hours without fail.
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Old 24th October 2010, 10:41 PM   #36
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You have certainly misread me. I wasn't talking of tubes in general but merely of the leftover 6H30 offered to diyers. I have hundreds, if not thousands of other tubes, mostly NOS and failure rates are indeed very low. It could certainly be a bad batch, but rejects make a lot more sense. The tubes supplied by ARC should be first rate and work for tens of thousands of hours without fail.
Thousands of tubes? Who are you?? Will bad 6h30s make noise in this LS25 MKII preamps? I understand the tubes are not used for gain purposes.

After consulting with ARC, I'll figure out what to do. Perhaps have them take a look at it and have them install their 6h30s while they are at it.

Thanks for your help, by the way. I am learning quite a bit.
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Old 26th October 2010, 12:54 PM   #37
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I spoke with Ben Jacoby. He's got a good reputation and also services ARC units here in NYC. He thinks it could be the fact that Focal 1027 be speakers are quite sensitve. Rated at 91db but more like 94db.

And the tubes are not ARC tested but just run of the mill 6h30s. However, you never know and he wants me to bring it in which I will.

In the mean time, I am really enjoying my music without the preamp going from my source to the VS60 poweramp. No noise, just music.

If I can find a way to connect all my sources and have a tape loop with a passive set up, that might be the ticket. Anyone know of such a passive preamp?
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Old 26th October 2010, 01:31 PM   #38
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can you make your own ?
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Old 26th October 2010, 02:39 PM   #39
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can you make your own ?
I suppose I can but am not really inclined to. I usually deal with electronics as a necessity to great music. But if no one already did the work to make such passive preamp, I guess I might have to... I am a full time musician and don't have too much time away from music.

By the way, on the +20v points on the LS25, I just set the trimmer so both points are at 20v? I can't make both exactly 20v. More like one point is at 20.3v and the other 20.01v. Is this okay?
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Old 26th October 2010, 02:48 PM   #40
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I suppose I can but am not really inclined to. I usually deal with electronics as a necessity to great music. But if no one already did the work to make such passive preamp, I guess I might have to... I am a full time musician and don't have too much time away from music.

......
fair enough

sorry - I can't help you with any particular finished product ;

Quote:
Originally Posted by GeneJazz View Post
.....

By the way, on the +20v points on the LS25, I just set the trimmer so both points are at 20v? I can't make both exactly 20v. More like one point is at 20.3v and the other 20.01v. Is this okay?
perfect .
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