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Post by myles on Jul 18, 2006 8:16:00 GMT -7
Tests on three Tesla NOS tubes from KCA NOS Tubes Mike at www.kcanostubes.com sent me a few tubes to test. There are two EF86 variants, a Tesla EF86 and a Tesla EF806. The shorter plate EF806S could really help a lot of Matchless DC-30 owners and folks that own EF86 amps that have physical microphonic issues. The ECC803S (12AX7 type) was a very smooth and articulate tube in listening tests. The gain is about on par with current production tubes but the construction is superior and this would be a long lasting tube. Keep in mind that I only had one sample of each and Mike at KCA can generally pick tubes with specific gain characteristics and he also offers very nice matching services. The test results are below as compared to book spec and in the case of the ECC803S dual triode, the matching curves are also shown. I will be testing the EF86 variants in the following amps initially: Victoria Sovereign Matchless DC-30 65 Amps London Dr Z Z-28, KT-45, Delta 88 and RxES
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mikek
Full Member
Posts: 144
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Post by mikek on Jul 18, 2006 10:56:16 GMT -7
Myles, this is fantastic information. Thank you so much. I was actually curious about the Tesla EF86 to try in my RxES, as well as the Tesla ECC803S.
I just bought a Tesla E83CC from Mike and I plan on dropping that in my VHT Valvulator, hopefully it will decrease some of the noise and treble peak in the stock Sovtek 12AX7WB.
The NOS Tesla tubes appear to be very high-quality, I'm surprised they're not mentioned more often, especially their EL34 and ECC802S.
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Post by myles on Jul 18, 2006 12:37:19 GMT -7
Myles, this is fantastic information. Thank you so much. I was actually curious about the Tesla EF86 to try in my RxES, as well as the Tesla ECC803S. I just bought a Tesla E83CC from Mike and I plan on dropping that in my VHT Valvulator, hopefully it will decrease some of the noise and treble peak in the stock Sovtek 12AX7WB. The NOS Tesla tubes appear to be very high-quality, I'm surprised they're not mentioned more often, especially their EL34 and ECC802S. Tesla is a funny sort of deal. Their EL34's were and are some of the very best ever. They did amazing tubes and there are many industry folks that think they were one of the very best makers of vacuum tubes. Hopefully they will stay a bit of a secret for a bit longer to keep the price down. Aspen at GT has a stash of personal Tesla EL34B tubes that he keeps for personal use or close friends. They are spectacular. I think you will notice a very nice change in replacing your 12AX7WB. It is a bit of a harsh tube that is also sort of flat. The Tesla has much nicer current drive to boot.
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Post by rcrecelius on Jul 19, 2006 7:05:53 GMT -7
Anxiously awaiting your opinion of the ef806s in a Z28. I had a NOS Mullard in mine and it went microphonic too quick(it was after pulling the chassis though...maybe I bumped it)...I'd like to see a more "budget friendly" replacement.
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Post by guitarman1 on Jul 19, 2006 7:37:10 GMT -7
Great stuff Myles....thanks! I can't wait to hear your listening test opinions. I'm wondering how these might compare to the Darios in a Stingray. Do you think think the shorter plates in the 806 will affect the tone adversely? I don't have much experience with EF86 type tubes, but I generally prefer the sound of long plates in 12ax7s. By the way Myles, are you familiar with the new production SED EF86? How do they compare to the Sovteks, or is it the same tube made by Svetlana for both SED and Sovtek? I also see that Tung Sol is making a EF806. Any opionons on these? Steve
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Post by myles on Jul 19, 2006 8:24:07 GMT -7
Great stuff Myles....thanks! I can't wait to hear your listening test opinions. I'm wondering how these might compare to the Darios in a Stingray. Do you think think the shorter plates in the 806 will affect the tone adversely? I don't have much experience with EF86 type tubes, but I generally prefer the sound of long plates in 12ax7s. By the way Myles, are you familiar with the new production SED EF86? How do they compare to the Sovteks, or is it the same tube made by Svetlana for both SED and Sovtek? I also see that Tung Sol is making a EF806. Any opionons on these? Steve Steve, On the EF86 and EF806 types, the plate length had no impact. These are pentodes and react much differently than a dual triode such as a 12AX7. Talk to Sam Austin (Sama in here) and if he brings his Stingray over we can play with them in his amp and he can write up a result. The original real Svetlanas were nice. The Sovteks were awful ... inconsistent, did not come close to EF86 spec ... way too high rather than low ... so were noisy and very very very prone to physical microphonics.
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Post by guitarman1 on Jul 20, 2006 5:56:33 GMT -7
Great stuff Myles....thanks! I can't wait to hear your listening test opinions. I'm wondering how these might compare to the Darios in a Stingray. Do you think think the shorter plates in the 806 will affect the tone adversely? I don't have much experience with EF86 type tubes, but I generally prefer the sound of long plates in 12ax7s. By the way Myles, are you familiar with the new production SED EF86? How do they compare to the Sovteks, or is it the same tube made by Svetlana for both SED and Sovtek? I also see that Tung Sol is making a EF806. Any opionons on these? Steve Steve, On the EF86 and EF806 types, the plate length had no impact. These are pentodes and react much differently than a dual triode such as a 12AX7. Talk to Sam Austin (Sama in here) and if he brings his Stingray over we can play with them in his amp and he can write up a result. The original real Svetlanas were nice. The Sovteks were awful ... inconsistent, did not come close to EF86 spec ... way too high rather than low ... so were noisy and very very very prone to physical microphonics. Great! Thanks Myles.
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Post by myles on Jul 20, 2006 9:12:26 GMT -7
Steve, On the EF86 and EF806 types, the plate length had no impact. These are pentodes and react much differently than a dual triode such as a 12AX7. Talk to Sam Austin (Sama in here) and if he brings his Stingray over we can play with them in his amp and he can write up a result. The original real Svetlanas were nice. The Sovteks were awful ... inconsistent, did not come close to EF86 spec ... way too high rather than low ... so were noisy and very very very prone to physical microphonics. Great! Thanks Myles. You are more than welcome
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Post by drew on Jul 25, 2006 12:44:04 GMT -7
Good info Myles. Can you tell me what the mutual conductance spec is and how it relates to the tubes performance.
And I'm curious why gain specs are listed as ~ does the infinity symbol in this case indicate that gain is variable and n/a for the type of tube spec data???
Thanks, Drew
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Post by myles on Jul 26, 2006 9:13:30 GMT -7
Good info Myles. Can you tell me what the mutual conductance spec is and how it relates to the tubes performance. And I'm curious why gain specs are listed as ~ does the infinity symbol in this case indicate that gain is variable and n/a for the type of tube spec data??? Thanks, Drew Drew, in some tests the ~ indicates that this parameter is not fixed but dependant on the amp circuit or application. Answering these other questions would fill books. There is no simple shortcut. Grab an RCA tube receiving manual from www.tubesandmore.com and start reading There is also a lot of info in part II of my 200+ page tube primer downloadable from my website.
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Post by taswegian on Jul 26, 2006 15:55:19 GMT -7
I have a slug of old brown base Telsa EL-34's from my rack power amp days. They were the only valve I liked in that old set up and with matched quads I kept them all after revalves. My old tech bought a huge amount of them in the early eighties as he thought they might get rare. Need to get them all tested. I should hang on to them just in case I get me a EL-34 amp sometime. ;D
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Post by myles on Jul 26, 2006 16:35:36 GMT -7
I have a slug of old brown base Telsa EL-34's from my rack power amp days. They were the only valve I liked in that old set up and with matched quads I kept them all after revalves. My old tech bought a huge amount of them in the early eighties as he thought they might get rare. Need to get them all tested. I should hang on to them just in case I get me a EL-34 amp sometime. ;D The Tesla EL-34 is going up in price and considered one of the best EL34's ever made. Hang onto those. Even if you never use them they can be sold for more and more each year. Darn it ... I wish you were not a major ocean away as I would be happy to test them for you for nothing.
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Post by drew on Jul 28, 2006 7:31:35 GMT -7
Myles, Thank You for the info. Tas, Send those EL34's to me and I'll test them em for ya! PS: I'm back in the Rt66 camp as one's coming Monday. I missed that organic big bottle grind.
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Post by taswegian on Jul 28, 2006 7:52:50 GMT -7
Funny thing was (or tragic) that I just had to junk my poor ol' Volks Kombie (It was fried out from my last "hippy trail") ;D and I had heaps of them lying in all the nooks and crannies of that van. Half of them were broken, but I still have a bucket of them at my parents house. I played that rig for 13 years and only ever put the brown base NOS Tesla's in it, so you can figure out how many tubes I have/had lying around. I even found one in my fishing tackle box a while ago?
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