RT2/50 biasing inquiry

[Jaded Faith]

So I took the plunge and have an RT2/50 on the way (thanks RD/Rich!).

Quick question on biasing preferences. I was reading the manual and see that there is a 10mV window for all tube types. That being said, I am going to be trying JJ 6L6's, EL34L's and KT88's in it. From those of you that use these types of tubes, what are your preferred bias settings for each? I did a search and read many different threads, but I thought an updated take on your views all in one place would be cool. Thanks in advance!

 

[joey_truelove]

Was that the EL34 or the E34L?

 

[Jaded Faith]

EL34L

 

[kc2eeb]

I tend to go towards the higher limit, BUT, I keep an eye on the plates of the output tubes and if I see ANY red glow on the plates (easier to see in the dark or low light) I back off a little. I then check periodically to see if it changes. The reason I go for the higher limit is when the tubes draw higher current at idle, they'll break into overdrive distortion earlier. When they are biased lower, they'll sound cleaner. Some will say "colder." Check out the "setting bias" video on the MTS Forum Index. All the Best! Pat L. P.S. The most important thing is to trust your ears! As long as you're in the recommended limits, it's really what sounds best to you!

 

[Jaded Faith]

Thanks for the reply and the heads up on the video. Great info and just what I was looking for.

One thing I haven't been able to find yet is the recommended range for the KT88's. Anyone have that info?

 

[JKD]

Thanks for the reply and the heads up on the video. Great info and just what I was looking for.

One thing I haven't been able to find yet is the recommended range for the KT88's. Anyone have that info?

For 500V plate voltage, I've been using 40 to 50mA...so set mine at 45.

 

[maximus1]

40 -45 is too cold on that tube. should be 50 at the very least, the kt-88 is one of the only tubes where a high bias is very acceptable. i'd start at 53-55. kt-88's are the only tubes i'll ever use in this amp, i've only got to compare the jj's and the eh versions so if anyone has used any other brands of kt-88 i'd like to hear the results. the eh's are good but i prefer the jj's over them but the jj's are considerably more expensive. i read somewhere that someone on here was really digging the sovteks which is cool but i've never been a sovtek guy and from what i hear the eh's truly are different than sovteks eventhough the same people make them. tung sol makes some but i've never heard anything on how they sound. jj power tubes and chinese pre amp tubes :twisted:

 

[JKD]

40 -45 is too cold on that tube. should be 50 at the very least, the kt-88 is one of the only tubes where a high bias is very acceptable. i'd start at 53-55. kt-88's are the only tubes i'll ever use in this amp, i've only got to compare the jj's and the eh versions so if anyone has used any other brands of kt-88 i'd like to hear the results. the eh's are good but i prefer the jj's over them but the jj's are considerably more expensive. i read somewhere that someone on here was really digging the sovteks which is cool but i've never been a sovtek guy and from what i hear the eh's truly are different than sovteks eventhough the same people make them. tung sol makes some but i've never heard anything on how they sound. jj power tubes and chinese pre amp tubes :twisted:

Didn't you run your 6L6s at about a million tho, or am I thinking of someone else?

 

[jmgman70]

40 -45 is too cold on that tube. should be 50 at the very least, the kt-88 is one of the only tubes where a high bias is very acceptable. i'd start at 53-55. kt-88's are the only tubes i'll ever use in this amp, i've only got to compare the jj's and the eh versions so if anyone has used any other brands of kt-88 i'd like to hear the results. the eh's are good but i prefer the jj's over them but the jj's are considerably more expensive. i read somewhere that someone on here was really digging the sovteks which is cool but i've never been a sovtek guy and from what i hear the eh's truly are different than sovteks eventhough the same people make them. tung sol makes some but i've never heard anything on how they sound. jj power tubes and chinese pre amp tubes :twisted:

Didn't you run your 6L6s at about a million tho, or am I thinking of someone else?

A million and 1 :shock: