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Post by antonio on Nov 12, 2021 3:29:44 GMT
Have biased my amplifier again today, tubes 1 and 3 I have been able to set at 0.35v, possibly a little low, but I've been happy with how the amplifier has been sounding, unfortunately tubes 2 and 4 I can only get up to 0.23v, the adjuster comes to the end. Does this mean the tubes are ready to be replaced, they still sound fine, and if they do need replacing my thoughts were to try some 6550's after seeing a very good review on You Tube. The gist of the review, the 6550's were not quite as detailed and punchy, but added a touch of warm with a wonderful midrange, still went very low, but maybe not with the same tightness of the KT88's. He said he had really enjoyed them, and at the moment, had no thoughts of changing back.
Anyone on here have experience with 6550's vs KT88's, would appreciate your comments, and before I forget the 6550's were Tung Sol's.
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Post by jandl100 on Nov 12, 2021 4:57:48 GMT
If you can't fault the sound of your kt88's I wouldn't worry too much about the bias setting (bearing in mind I'm a technonumpty). Buying a new set of 6550 might open up a new world of pain and sorrow if they turn out to be iffy - valves can do that! 6550 would defo change the sound, but then ime valves vary sonically as much by make as they do by type. I'm not sure why you think a YouTube reviewer would have the same tastes as you do. I suspect you watch too much of that stuff.  Valves are going to react differently in different circuits anyway, so unless you're using the same amp as the reviewer it's difficult to read too much into his opinions... imo! In my own setup (Primaluna valve power amps) I like the sound of KT88. The basic Primaluna Sound is imo just a bit too neutral dynamically, verging on blandness if you aren't careful. I like the kt88 I have (Primaluna brand which are 'selected' Chinese Shuguang which are a knockoff of a famous brand which I can't recall atm! - the info is buried somewhere on the Primaluna website!) adding a bit more punch and vitality, while retaining subtlety, the 6550 I tried (Edicron) didn't do that. |
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Post by antonio on Nov 12, 2021 8:16:39 GMT
Thank you Jerry, you've given me something to think about, I don't think I'm doing the amp any harm as it is. I wouldn't say this amp is bland, to me it comes across as quite lively sounding with KT88's in there. At the moment I am sitting much closer to the speakers than I have previously done, not that I mind, just thought the 6550's would make for a nice change, I don't think there is too much of a difference, and although I enjoy this amp I am often left wondering if I should have gone for an EL34 amp I did ask the supplier many months ago if the amp was suitable to use with KT90's and 6550's and the answer is yes, he did also add the 6550's are a good match with this amp. As for YT, I probably did watch a little bit too much, not so nowadays, but some of the sound clips can be pretty good, and when I said reviewer, not a professional, just a bloke who was genuinely keen to pass on info to others, or at least that is how he came across, he also did a three track sound demo and I have to say there was nothing wrong with it through my headphones. I know I can get Shuguang KT88's or even their KT88 - Z's which have had good reviews, I shall give it some more thought  Back onto you, I was a little surprised you are using KT88's, I thought you were using 6L6's, but pleased you are still enjoying both your Prima Luna amps. |
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Post by jandl100 on Nov 12, 2021 8:55:50 GMT
EL34, my least favourite power valve. The only ones I've heard give a moderately decent performance are TADs. Apart from the TADs, if you're suffering from insomnia EL34 would be a good choice. I just don't understand the EL34 fanboy thing, but maybe it's just me. 6L6.Yep,ive got a newish octet, and I do like them. But atm I'm enjoying the greater get up & go from the kt88s. They go better for me with the Primaluna sound atm. |
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Post by karma67 on Nov 12, 2021 9:52:14 GMT
Just bear in mind that if a tube fails it will probably take out some resistors and a fuse
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Post by firebottle on Nov 12, 2021 10:56:11 GMT
Generally speaking if you can't get the bias up the tube is probably losing emission.
This is a much better state of affairs than the bias keeps on climbing, as if the tube goes into runaway things can get serious and expensive. Worst case scenario if there isn't a fuse in circuit could be a blown output transformer.
Providing you can't hear any obvious distortion then keep using them.
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Post by antonio on Nov 12, 2021 12:38:47 GMT
Thanks for your comments gentlemen, I will bear in mind what you ave said and at least for now will keep on using the amp, the only problem is if something does go wrong I don't know of anyone to repair it.
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Valves are going to react differently in different circuits anyway, so unless you're using the same amp as the reviewer it's difficult to read too much into his opinions... imo! 
