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Traynor YBA 3 custom special power tube question.

jazzbass_5

jazzbass_5

Sep 1, 2007
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NY, Medina
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#1
So, I did some required maintenance and some additions to my 1971 YBA-3 (black velvet mods) that will help me check bias grid currents (and a black velvet mod to run the unit at lower power with 2 tubes instead of 4).

In checking the bias grid currents on the quartet I see that the original 6CA7 are in need of replacement.

What recommendations do you all have on power tube replacement?
We have of course.
6CA7
EL34
With a few modes and biasing differences we also have:
KT88
6550
20241127_065344.jpg
20241127_065232.jpg
20241127_065034.jpg
 
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#6
jazzbass_5 said:
My buddy works there in Niagara Falls, I'll get a hold of him and ask. Probably 6CA7s or EL34s.
But, this is more directed towards those that have modified and tube rolled their units, what pros and cons there are.
Thanks though Agedhorse, nice to see you still active here :)
Click to expand...
That’s what I would suggest too. I’m wary of rolling very different tubes into an output section due to potential problems, but that’s me. All I see are problems that other folks create.
 
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#7
The original tube type is in production. IMHO stick with original unless there is a good reason to change.


Changing the tube type may or may not have an audible impact.


My Aguilar DB359 is running vintage Svetlana 6550C (later known as Winged C). I swapped in some JJ KT88s and did not hear any difference.

I do hear a difference between JJ and Shuguang KT88.

My Sadowksy SA200s were running Shuguang EL34B (this was the factory tube). Sadowsky now recommends KT88 (for increased reliability). Recommended bias current remains the same. Both amps are running the factory original preamp tubes, and they did not sound exactly alike. I believe the tone changed slightly with KT88. The change is so subtle that I can't really say how it's different. My impression is power with KT88 either remained the same or decreased slightly.

As far as rolling tubes. I think the best approach is to identify how you hope to modify the sound and feel of the amp. Then research and select tubes with the reputation for producing the desired change.
 
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#8
jazzbass_5 said:
So, I did some required maintenance and some additions to my 1971 YBA-3 (black velvet mods) that will help me check bias grid currents (and a black velvet mod to run the unit at lower power with 2 tubes instead of 4).

In checking the bias grid currents on the quartet I see that the original 6CA7 are in need of replacement.

What recommendations do you all have on power tube replacement?
We have of course.
6CA7
EL34
With a few modes and biasing differences we also have:
KT88
6550
View attachment 7086889View attachment 7086890View attachment 7086891
Click to expand...
Any EL34 matched quad of good known quality. I run mine with a quad of Marshall’s (probably rebranded Shuguangs) since two years. Bias adjusted in the 55-60 percent dissipation range if I remember well.
 
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#9
I have used the EH EL-34's, some what good sounding, but they didn't last long, before losing power ( these were installed in an amp that I bought, don't know how long they were in it before I purchased it ), all the amps that I restored/worked on ( I have 3 YBA-3's ), I loaded them up with JJ EL-34L's, they bias up good ( using the 4 volt, voltage drop method across the 10 watt 470 ohm resistor, this is the factory method, when the amps were made, I do have one amp that has the 10 watt 1000 ohm resistor, which calls for a 8 volt drop), ran one amp in heavy rotation ( meaning, playing every weekend for a year ) , had really no issues, checked the tubes with my Hickok 539c tube tester, and no issues ( tested good no shorts, good emissions ), I don't gig these amps anymore, mainly use them for band rehearsals, so there not pushed hard, I was running these amps into a 4 ohm load ( the spec's call for a 8 ohm load ), the best tubes are the Sylvania/ Phillips 6CA7's, hard to find, in new - to good spec's/condition, you have to remember tubes are a consumable item, and new tubes nowadays, are a crap shoot, so, I have had good luck, with JJ's & Sovtek, as a side note, I once had a Peavey VB-2, and swapped out the stock tubes, and installed the EH 6CA7's, sounded good when pushed somewhat hard, as always your milage may vary
 
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#10
jastacey said:
I have used the EH EL-34's, some what good sounding, but they didn't last long, before losing power ( these were installed in an amp that I bought, don't know how long they were in it before I purchased it ), all the amps that I restored/worked on ( I have 3 YBA-3's ), I loaded them up with JJ EL-34L's, they bias up good ( using the 4 volt, voltage drop method across the 10 watt 470 ohm resistor, this is the factory method, when the amps were made, I do have one amp that has the 10 watt 1000 ohm resistor, which calls for a 8 volt drop), ran one amp in heavy rotation ( meaning, playing every weekend for a year ) , had really no issues, checked the tubes with my Hickok 539c tube tester, and no issues ( tested good no shorts, good emissions ), I don't gig these amps anymore, mainly use them for band rehearsals, so there not pushed hard, I was running these amps into a 4 ohm load ( the spec's call for a 8 ohm load ), the best tubes are the Sylvania/ Phillips 6CA7's, hard to find, in new - to good spec's/condition, you have to remember tubes are a consumable item, and new tubes nowadays, are a crap shoot, so, I have had good luck, with JJ's & Sovtek, as a side note, I once had a Peavey VB-2, and swapped out the stock tubes, and installed the EH 6CA7's, sounded good when pushed somewhat hard, as always your milage may vary
Click to expand...
A good, real NOS or lightly used quad of Philips would probably cost an arm, a leg… and maybe a kidney or two :)

I have one lonely Philips (testing good) that came with a (now sold) YBA-1. I don’t know what to do with as I tried to match it with other EL34’s but couldn’t find a good mate, bias current wise.

As for EH EL34’s, one of my two YGL3’s came with a quad but they were really tired. Now replaced with a good quad of old Tesla’s (not JJ’s) from the 70´s or early 80’s.
 
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#11
These amps will weed out sub par tubes pretty quick, they tend to run fairly high B+. Original 6CA7's were stout and barely broke a sweat. New production tubes can suffer under the strain no matter what the label, glass or base numbers/letters are stamped on them. IMHO I would stay with a pentode like the 6CA7/EL34/KT-77 instead of a beam power tube.
 
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#12
It looks like the amp was modded with care. I like F&T electrolytics. That model is often found highly modded. EL34’s and KT77’s are good replacements for the 6CA7. Pay attention to the bias.

Much easier, both JJ and EHX make reissue 6CA7’s so they are available. EHX has been selling them for 20 years, players like them.
 
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#15
beans-on-toast said:
It looks like the amp was modded with care. I like F&T electrolytics. That model is often found highly modded. EL34’s and KT77’s are good replacements for the 6CA7. Pay attention to the bias.

Much easier, both JJ and EHX make reissue 6CA7’s so they are available. EHX has been selling them for 20 years, players like them.
Click to expand...
I try to be clean when I do my mods, thanks.
 
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