Is the sound in both channels or just one? If it's in one channel try swapping the tubes from one channel to the other and see if the noise changes sides. The power tubes are the large tubes yes and swap those they are most likely the culprit if it is in fact a tube or tubes going bad.
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
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Pima Luna uses auto-biasing and runs their tubes at very low voltages. Tubes should last many years. Any given tube can always go bad of course, but with this being a fairly new amp I'm sure Prima Luna if not the selling dealer, would want to know about it. What did they say? Yes the power tubes are the large ones. Probably EL34, about as warm and musical a tube as you could ever hope to find. Prima Luna are designed to run with a lot of different tubes though, so feel free to knock yourself out. My bet is after a lot of time and money you come back to where you started. As far as power goes, that one is even more clear: No, you do not want as much as possible. Why? Granted one of the hardest things to learn, but watts just don't matter. What matters is how it sounds during the vast majority of the time you're not clipping. Which unless you have awfully inefficient speakers (which you said horns, so no way), or crank it really super loud, might be never. If you want musical, upgrade to a tube preamp. If you want louder, upgrade by adding a swarm bass array (several subwoofers). But I would start by ditching the solid state. |
Not true for vacuum tubes you get with stock amps are not verygood vs the originals from 1970 on down .the vacuum is of the gasses the inspection of the grids on average over 10 % variances inside gridsor more years ago 2-3% was common the materials not even close maybe 3000 hours on average NOS tubes from the 50s many times 10,000 hours , some rectifiers run for10 years . Emissions labs in Europe are great as well as a few others for premium brands . Call vacuum tube services, or Brent Jesse recordings to get true New closely matched vacuum tubes a big upgrade in sound also..I grew up on all the classic tubes and the majority of Chinese, and Russia tubes are average at best compared. |
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 |
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/ |
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. |