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Tubes for Audible Illusions Modulus 3A?

I have an AI M3A from around 1995 that seems to eat tubes on a regular basis. I got it used in an A-Gon purchase,it had stock Sovtek tubes,which were clearly past their prime. I've since tried some Electro-Harmonix 6922's,which developed noise very quickly,some Golden Dragon 6DJ8's which lasted a bit longer,but now one is hissing away in the left channel. Should I bite the bullet and pay AI's ridiculous price of 35.00 per tube,or has anyone had good experiences with alternatives for less money? Thanks. Bob LaBarca
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Showing 3 responses by jcus

jcus
26 posts
 
Bob, Considering we burn-in, test, grade and carefully select each tube we sell I don't think $35 is ridiculous. Also, our tubes have a 90 day warranty. Regards, Jerry/AI's Service Mgr.
jcus
26 posts
 
Audible Illusions advises caution when using NOS tubes in ours or several other mfgs open-loop no-feedback circuits. Also the 6DJ8 design was never really intended to be used in high performance audio circuits. They worked great in TV sets and oscilloscopes but they tend to be microphonic due to their small plates and thin mica structures. Most 6922 tubes have heaver mica structures and exhibit less microphony. We've found that the Russian, military grade, tubes perform the best in our circuits.

Regarding leaving your preamp on all the time, please understand the optimum life for good tubes is 2-3000 hrs. Our stand-by circuit prevents thermal shock and, over the past 20 years, we've proven it prolongs tube life. Regards, Jerry/AI's Service Mgr.

jcus
26 posts
 
Docknow, Judging from your message, I see nothing wrong with disconnecting AC from your M3a/audio system during long periods. I highly reccommend this practice during lightning storms. Your M3a uses apx 45 volts which won't make much of a dent in your electric bill. Don't know about the rest of your system. Regards, Jerry
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