2. amps-preamps
  3. 151517-136934

Tube Failure question

I am new to tubes. I have Primaluna Prologue mono blocks. I have had the amps for about a year. Also using solid state bryston preamp. Lately I have popping and at higher volume last night some screeching sounds that go away at lower volume. Can this be a tube failure? If so I would like to have good sounding tubes with as much power as possible. Suggestions? I am assuming that the power tubes are the large ones. Is this correct? If so suggestions for the smaller tubes to sound warm and musical? Speakers are large with separate horns and tweeters. I live in Canada so if possible would like to buy tubes here. All suggestions welcome. Thanks, Tom
twotone23
twotone23 OP
3 posts
 
Thanks to all for the advice as I said I am new to tubes so dont really know the pros and cons of different tubes. 
I have not contacted Primaluna but will now thanks to the advice here.
The small tubes I have are 12AU7 and the large ones are KT 88. 
I see suggestions for EL 34 and Tung Sol 7581 Can someone give me there thoughts on the differences between them and KT 88? 
Lastly the noise does sound as if the amp is clipping (popping) but is not consistant. Am I right to assume tubes?
Can I but tubes somewhere in Canada? I am in Ontario.
Thanks again.
Tom
twotone23 OP
3 posts
 
Forgot to say the amps are Prologue 7 mono blocks
The issue I have is intermittent but increases with volume. This makes it hard to change out tubes to test.
I have heard I should wear gloves to touch the tubes is this correct?
facten
2,878 posts
 
Yes wear gloves
A couple of places in Canada where you can order tubes, if you google you may find others

https://www.thetubestore.com/
https://www.partsconnexion.com/
twotone23 OP
3 posts
 
Thanks Facten. 

jwcinsd
17 posts
 
Call Kevin Deal at Upscale Audio in LA. He’s the USA importer for PrimaLuna and may be the North American importer. He’s one of the most knowledgeable guys in tubes in general, especially every model of PrimaLuna. I used to have the PrimaLuna Dialogue 7 monos. I had a bad tube in the first year or so and then went 4-5 years trouble free. Trouble free and magical, I might add. I switched from KT88s to KT77s. A bit less power but a touch more magic. Be careful of asking for more power as the PrimaLunas are not really high power amps. I assume you bought them to match with your current speakers. Without doubling your power you’ll really not gaining much by adding a few more watts and again you may lose a bit of musicality. Someone here said that PrimaLunas run tubes at very low power, that’s very true as now I moved up to a more powerful KT88 amp and although it has more bass and detail, it is definitely a tad less musical than the PrimaLunas in triode mode with KT77s but now I buy 4 new KT88s every year. It’s too bad I couldn’t keep both because my current amp is amazing, but there are days when I look in the for sale section for some Dialogue 7s. Call Kevin. 
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