Willsenton's R8 KT88/EL34 Tube Amplifier

With my Primaluna Dialogue 4 and 5-the Psvane SIno/Shuguang seem to be a slightly better match then the New Sensor Reflektor tubes. Just ordered a set of Psvane EL34 UK to compare to the Psvane EL34C and Shuguang EL34b (ran across a qaud of new old stock)-in the Prologue 4. Not to mention KT88's don't sound as good as the EL34 in the 4. Visa versa with the 5. Seem to reason they were voiced with particular tubes in mind.
 
automojo said:
With my Primaluna Dialogue 4 and 5-the Psvane SIno/Shuguang seem to be a slightly better match then the New Sensor Reflektor tubes. Just ordered a set of Psvane EL34 UK to compare to the Psvane EL34C and Shuguang EL34b (ran across a qaud of new old stock)-in the Prologue 4. Not to mention KT88's don't sound as good as the EL34 in the 4. Visa versa with the 5. Seem to reason they were voiced with particular tubes in mind.
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I keep going back to my JJ EL34L tubes. They sound way better than their low price would indicate. I've rolled about a dozen different EL34/6CA7 tubes into my 6SQ7 SE amp and the JJ tubes clearly just sound better to me. I haven't tried a set in the R8 yet so can't comment yet on what they sound like in that amp.
 
Sure-I think the JJ's are decent tubes for sure. I didn't have a issue with them-the Psvane have a wider deeper soundstage-and do that 3d depth thing. Agreed the JJ's (l's) are a great sounding tube. In my setup musical and extended, but more one dimensional. Another good tube for PL's is the Sino/Shuguang EL34B with2 halo getters. Still a few quads out there for $60-70 matched/tested. For the KT88 Prologue 5-the Shuguang KT88/98 works well-along with the JJ kt88-suprisingly. Powerful bass and musical.
Just my experience-the Chinese tubes tend to have a wider airey soundstage then most Reflector/New Sensor tubes. The better ones do it without added brightness.
The Russian/Chez tubes are usually more focused and direct. Some certainly like that better then the latter. The 3d type New Sensors-like some Tungsol-IMHO add brightness to the mix like the early Chinese tubes. Or alternatively they sound a bit flat/dull -like some JJ preamp tubes.
If your gear was designed around the JJ's-like my Van Alstine preamp-then you don' t hear that-and a GL for example sounds a bit bright.
 
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The real question is can anyone actually hear these reported differences between say an EL34 made in Slovakia (JJ), EL34 made in Saratov (New Sensor) or an EL34 made in Shuguang in a blind test?

No.

I really liked the tubes made in Saint Petersburg Russia, no surprise since they purchased an entire assembly line from RCA including production licensing. These are the "winged C" tubes but no longer available the last I checked.

Unless you run zero or very low feedback amplifiers there isn't going to be audible differences but even a zero feedback amplifier may show differences between tubes from the same factory of origin. This makes generalizing the sound of a particular tube from it's origin kinda ridiculous.

Just my $.02
 
capbeefheart said:
The real question is can anyone actually hear these reported differences between say an EL34 made in Slovakia (JJ), EL34 made in Saratov (New Sensor) or an EL34 made in Shuguang in a blind test?

No.

I really liked the tubes made in Saint Petersburg Russia, no surprise since they purchased an entire assembly line from RCA including production licensing. These are the "winged C" tubes but no longer available the last I checked.

Unless you run zero or very low feedback amplifiers there isn't going to be audible differences but even a zero feedback amplifier may show differences between tubes from the same factory of origin. This makes generalizing the sound of a particular tube from it's origin kinda ridiculous.

Just my $.02
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People hear differences all the time with different tubes.
No new news here.
FIY Primaluna amps-at least the early ones don't use any feedback.

As far as being ridiculous-seem it begs the question: your generalizing/speculating people can't/won't hear the differences in your example then is even more ridiculous??
Speculating on if people here differences or not-just because another group can't-makes zero sense.
The best thing is to find out for yourself-instead of taking someone else word. What many of us do here including myself. As everything audio/tubes cables, caps guides are helpful but not the end game.
 
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automojo said:
People hear differences all the time with different tubes.
No new news here.
FIY Primaluna amps-at least the early ones don't use any feedback.

As far as being ridiculous-seem it begs the question: your generalizing/speculating people can't/won't hear the differences in your example then is even more ridiculous??
Speculating on if people here differences or not-just because another group can't-makes zero sense.
The best thing is to find out for yourself-instead of taking someone else word. What many of us do here including myself. As everything audio/tubes cables, caps guides are helpful but not the end game.
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Maybe I wasn't clear enough. I never said there aren't audible differences between tubes.

What I said was with an amp with a lot of feedback the differences won't be audible. Amps with little or no feedback you can hear the difference. But, it's not just a difference between different tube manufacturers but also within the same production batch of one manufacturer. E.g. Install 5 different 300b tubes from the same manufacturer in a zero feedback amplifier and they will not all perform the same. I.e. Even the from the same manufacturer tubes can sound different.

Or, give me enough samples of say 12AX7 from RCA and Mullard to screen and I'll find one from each manufacturer that will sound identical.
 
capbeefheart said:
Maybe I wasn't clear enough. I never said there aren't audible differences between tubes.

What I said was with an amp with a lot of feedback the differences won't be audible. Amps with little or no feedback you can hear the difference. But, it's not just a difference between different tube manufacturers but also within the same production batch of one manufacturer. E.g. Install 5 different 300b tubes from the same manufacturer in a zero feedback amplifier and they will not all perform the same. I.e. Even the from the same manufacturer tubes can sound different.
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Gotcha!
 
capbeefheart said:
I see no special considerations needed for feedback wiring. I wouldn't use shielded wire, your standard 18awg hookup wire is completely adequate. I'd probably still try and avoid running it in through EMF fields caused from power transformers or chokes. But luckily with tube amps most of those big EMF fields are above the chassis where the transformers stick out from, the only one under the hood would be right next to the rectifier.
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Thank you. If I were to do this variable/adjustable GNFB, do you think a 2 pole variable resistor would be a good way to go, or would they likely have some inaccuracy between the channels that would make a switch better? I considered a rotary switch with about 5 positions instead so I could choose my resistor type and quality and have them matched. I'm just not sure if there are certain switch or variable resistor types to stay away from that could affect sound quality over simply have a single fixed resistor in place.
 
If anyone is experiencing a noisy volume pot on the R8, try this and see if it fixes it. Remove all the tubes and clean the pins with Caig's DeOxit. After cleaning wipe down all the pins with a soft cloth or paper towel. If I am correct, there will be a LOT of black oxidation residue. Wipe the pins thoroughly and remove all the black residue. I use socket savers and old tubes. I was surprised at how much oxidation was on the pins. Once I cleaned all the residue, the pins were left shiny. Reinstalling the tubes made almost all the noise go away. Installing the socket savers brought back some of the noise but it was barely audible.
 
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You might want to consider buying vintage 6SN7/6SL7 tubes iso the Chinese-made TADs. They can readily be found on eBay at about the same price. You just have to look for tubes that have been tested. I have been burned by a couple of tubes that were not tested and were nearly dead. When looking at used tubes, look for tubes with near matching scores. 6SL7/6SN7 tubes will have two scores.

6SL7 tubes are high gain and the values would be around 75-80. So you would look for tubes that show scores like 80/80. Then look to see that both tubes have nearly the same scores. Scores within 5% are excellent, although with 10% is acceptable. If the tubes are not matching, they can shift the sound to one side, e.g. to the left or right from the center.

6SN7 tubes are medium gain, so scores of 18-21 are normal. Again, look for tubes are matched, e.g. 18.6/19.0 would be pretty good.

Recommended brands would be the Sylvania, RCA or Tung-Sol 6SN7GT/6SN7GTA/6SL7GT tubes, recommended GE tubes would be the 6SN7GTA/B or 6SL7GT tubes. Generally, the older the tube, the better they sound but they are harder to find and more expensive, also they would be prone to be noisy.

I noticed that the price of tubes have been increasing by quite a bit. My favorite tubes are the 6SN7W for the1940s. I bought them last year for about $40-60 each but am shocked to see them asking for $200/each. The Sylvania and RCA 6SN7-GTAs can be found for about $30-40 per tube. GE tubes can be found for a bit less but do sound a bit less musical than the others. The differences are very subtle. The good point about vintage tubes is that they are very reliable. Some pre-amp tubes can last up to 10,000 hours, modern pre-amp tubes usually last about 2,000 to 4,000 hours (new power tubes have a shorter life-span due to their high heat, about 700-2,000 hours, you get what you pay for). But nearly all tubes sold are used. You cannot find out how many hours are on the tubes. The alternative would be to buy unused or NOS (New Old Stock) tubes but the prices are accordingly higher.

On the R8, the 6SL7 tubes make the most difference in the sound. In fact, the R8 usually sells the amps with Russian 6SL7 6N9S (6SL7 compatible) tubes and they are actually decent tubes. You can tell if they are Russian tubes if they have the OTK stamp on the tubes or if is labeled 6N9S. You will find that there are not many options for the 6SL7s as they were not as popular as the 6SN7s. The only new production 6SL7 tubes are the Electro-Harmonix and Tung-Sol with some from Lin Lai.

The power tubes do not affect the sound that much. If your taste leans toward rock, go for the KT-88s for tighter bass but are a bit bright. The EL34s are best for classical, jazz or vocal music. They have softer bass with a more mellow high and midrange.

My favorite tubes right now are the Sylvania 6SN7W or 6SN7GTs (VT231), Sylvania 6SL7GT (VT229) and the reissued Russian-made Mullard EL34s. If sticking with the KT-88, I'd look at the Gold Lion KT-88s. I would avoid Chinese tubes as their quality is inconsistent. I have two quads of Psvane El34-PH tubes. One quad scores 26 and the other scores 45. Each quad is a matched set but with such disparate scores, you cannot mix and match the two quads. I find that the New Sensor (i.e. Mullard, Gold Lion, Sovtek, Tung-Sol, Svetlana and EH) tubes to be more consistent with scores pretty much the same.

Hope this helps and does not confuse you.
 
Jon S said:
You might want to consider buying vintage 6SN7/6SL7 tubes iso the Chinese-made TADs. They can readily be found on eBay at about the same price. You just have to look for tubes that have been tested. I have been burned by a couple of tubes that were not tested and were nearly dead. When looking at used tubes, look for tubes with near matching scores. 6SL7/6SN7 tubes will have two scores.

6SL7 tubes are high gain and the values would be around 75-80. So you would look for tubes that show scores like 80/80. Then look to see that both tubes have nearly the same scores. Scores within 5% are excellent, although with 10% is acceptable. If the tubes are not matching, they can shift the sound to one side, e.g. to the left or right from the center.

6SN7 tubes are medium gain, so scores of 18-21 are normal. Again, look for tubes are matched, e.g. 18.6/19.0 would be pretty good.

Recommended brands would be the Sylvania, RCA or Tung-Sol 6SN7GT/6SN7GTA/6SL7GT tubes, recommended GE tubes would be the 6SN7GTA/B or 6SL7GT tubes. Generally, the older the tube, the better they sound but they are harder to find and more expensive, also they would be prone to be noisy.

I noticed that the price of tubes have been increasing by quite a bit. My favorite tubes are the 6SN7W for the1940s. I bought them last year for about $40-60 each but am shocked to see them asking for $200/each. The Sylvania and RCA 6SN7-GTAs can be found for about $30-40 per tube. GE tubes can be found for a bit less but do sound a bit less musical than the others. The differences are very subtle. The good point about vintage tubes is that they are very reliable. Some pre-amp tubes can last up to 10,000 hours, modern pre-amp tubes usually last about 2,000 to 4,000 hours (new power tubes have a shorter life-span due to their high heat, about 700-2,000 hours, you get what you pay for). But nearly all tubes sold are used. You cannot find out how many hours are on the tubes. The alternative would be to buy unused or NOS (New Old Stock) tubes but the prices are accordingly higher.

On the R8, the 6SL7 tubes make the most difference in the sound. In fact, the R8 usually sells the amps with Russian 6SL7 6N9S (6SL7 compatible) tubes and they are actually decent tubes. You can tell if they are Russian tubes if they have the OTK stamp on the tubes or if is labeled 6N9S. You will find that there are not many options for the 6SL7s as they were not as popular as the 6SN7s. The only new production 6SL7 tubes are the Electro-Harmonix and Tung-Sol with some from Lin Lai.

The power tubes do not affect the sound that much. If your taste leans toward rock, go for the KT-88s for tighter bass but are a bit bright. The EL34s are best for classical, jazz or vocal music. They have softer bass with a more mellow high and midrange.

My favorite tubes right now are the Sylvania 6SN7W or 6SN7GTs (VT231), Sylvania 6SL7GT (VT229) and the reissued Russian-made Mullard EL34s. If sticking with the KT-88, I'd look at the Gold Lion KT-88s. I would avoid Chinese tubes as their quality is inconsistent. I have two quads of Psvane El34-PH tubes. One quad scores 26 and the other scores 45. Each quad is a matched set but with such disparate scores, you cannot mix and match the two quads. I find that the New Sensor (i.e. Mullard, Gold Lion, Sovtek, Tung-Sol, Svetlana and EH) tubes to be more consistent with scores pretty much the same.

Hope this helps and does not confuse you.
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Nice reply. For now I am thinking of new produce and not NOS. The TAD seems to be new produce.
 
Jon S said:
The only new production 6SL7 tubes are the Electro-Harmonix and Tung-Sol with some from Lin Lai.
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and sovtek, JJ, TAD-rebranded chinese-made, psvane. didnt shuguang restart their operation?
sophia electric has pretty much run out of those leftover tj full music. northern electric is still selling them.

excellent post/reply btw.
 
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Jon S said:
6SL7 tubes are high gain and the values would be around 75-80....
Jon S said:
6SN7 tubes are medium gain, so scores of 18-21 are normal.
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Anyone offering tubes with a "score" hasn't tested them properly. Tube matching requires at least a gm measurement, and preferably also a current measurement with nominal voltages and bias applied.

Jack
 
I've never heard of such a "scoring" system for tubes. I have a supposedly matched pair of Psvane 300B's marked "75" by the seller. That doesn't mean they have a gain of 75! It's just some ranking system the seller uses for matching tubes. A Gm number would be more helpful but it is what it is. I have to take it on faith that the tubes are strong and matched, and it happens that they are. But whatever numbering system they use clearly has nothing to do with gain.
 
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