Don't put SED Winged C 6L6's in your 5150 III

D

deadweight

New member
I tried it out yesterday, biased it up a tiny bit hot only by about 1ma or less. The cleans were decent but the 3rd channel was just lacking the balls that the factory tubes had. I just put in some JJ 6L6's and it sounds pretty close to the factory tubes which leads me to believe they use rebranded JJ's. Either way, it doesnt seem to me that the SED's are the right tube for this amp.
 
Thats exactly what I was saying in another thread....... Everyone seems to be SED 6L6 fans and Im not saying they arent good tubes or do not sound good in other amps. However they did not do it for me in the 5150 III ... My 5150 III came stock with JJ powertubes.. I decided to try the SED's in there to see what the difference would be and was disappointed. The SED's lacked clarity especially on channel 3 and gave the amp a mushy feel. They did have nice character but it was just overkill with this amp. The JJ's give the amp a clearer and tighter tone, everything holds together better.
 
yeah im thinking they are jj's that came in mine they just dont have the red print on them, they have little white stickers on the base that say white 7 on them
 
i biased them using the plate voltage at 487 which i measured and a 25 watt dissipation at 70 % and went about 1ma hotter, and i forgot to measure the factory bias but ive heard they bias a little cold. Im now kind of curious as to what it would sound like with gold lion kt66's
 
Amps designed for 'clean' power sections are supposed to have their power tubes biased 'cold' :confused:

Bias them properly, then come back and give a proper review.
 
deadweight":j5kdunnh said:
ok so whats "proper"?
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I would just stick with the factory bias. A quick google search shows factory ranges of around 18-21mA. I would try them in that range and see if it clears things up. I've got a pair of Winged C 6L6 in my Recto which increased the clean headroom of the amp threefold and I didn't touch the factory bias. You may like it better that way.
 
hm possibly. the thing with that is i used the same formula to bias the jj's and the sed's and i much prefer the sound of the jj's, wether its biased "properly" or not. plus if you had read the original post "properly" you'd know that I wasnt saying the SED's are bad tubes by any means, just that I (and its a personal preference) dont think these tubes are the best for this particular amp.
 
deadweight":v4id8g2r said:
i biased them using the plate voltage at 487 which i measured and a 25 watt dissipation at 70 % and went about 1ma hotter, and i forgot to measure the factory bias but ive heard they bias a little cold. Im now kind of curious as to what it would sound like with gold lion kt66's
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According to the data sheets, the SED 6L6 is a 32 watt tube and the JJ is a 30 watt tube....I rarely go up past 60% when biasing, depends on how hard you run the amp.

With the SED I'd try 39 ma and with the JJ 36 ma per tube (if your PV is 487).....
 
ok so i was a little bit cold because i was at about 37.5 ma give or take and right on par with the JJ's but the differnce in bite on channel 3 was HUGE. so for now im gonna stick to the JJ's and ive sent an email to bob at eurotubes to ask what his thoughts on putting in kt66's are, Id like to fatten up the sound a bit
 
deadweight":1t9gxp5q said:
ok so i was a little bit cold because i was at about 37.5 ma give or take and right on par with the JJ's but the differnce in bite on channel 3 was HUGE. so for now im gonna stick to the JJ's and ive sent an email to bob at eurotubes to ask what his thoughts on putting in kt66's are, Id like to fatten up the sound a bit
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I doubt power tubes would only affect one channel's tone. Did you change preamp tubes too?
 
no it probably affected all channels but i liked the clean fine i just didnt like the lead channel is all. I did change the preamp tubes but i did that weeks ago, which i liked the result of. I put tung sols in v2-v8 and put a jj ecc81 in v1 which in my opinion did wonders for the clean channel (not saying it didnt affect everything, i know v1 is for all channels)
 
Try putting an ecc83 back in V1 with the SED's back in and see what that does. It could be that the combination of having a ecc81 in there with the JJ's worked for you but that combo might not jive with the SED's.
 
deadweight":epz66aee said:
no it probably affected all channels but i liked the clean fine i just didnt like the lead channel is all. I did change the preamp tubes but i did that weeks ago, which i liked the result of. I put tung sols in v2-v8 and put a jj ecc81 in v1 which in my opinion did wonders for the clean channel (not saying it didnt affect everything, i know v1 is for all channels)
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Are there preamp tubes that are dedicated to only that channel? One of those in that channel could be funky too.
 
Guys seriously I had the same experience that deadweight had. SED's not so good in the 5153...... JJ's very nice in the 5153 ! ! ! I treid running them both at different bias settings and prefer the JJ's at about 29ma

I am also curious about how it might sound with Kt66's.
 
JakeAC5253":1yfp3s1i said:
deadweight":1yfp3s1i said:
ok so whats "proper"?
Click to expand...

I would just stick with the factory bias. A quick google search shows factory ranges of around 18-21mA. I would try them in that range and see if it clears things up. I've got a pair of Winged C 6L6 in my Recto which increased the clean headroom of the amp threefold and I didn't touch the factory bias. You may like it better that way.
Click to expand...

Dave Friedman recommended higher bias settings numerous times. He's usually right about tone. :confused:
 
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