dsl biasing issue I've never seen before...?

txmack · 10-29-2009, 07:35 PM

Okay, this is my third or fourth DSL 50.

I have always set the bias myself, as I have before with this amp.
I just got in some new, matched winged c's, popped them in and the left tube will not
go lower than 41. I have it turned all the way clockwise to get it there.

Other side goes down to 38-39 range just fine, but 41 is the only place I can get them to balance. Sounds good, little loud maybe, but do I have a problem here? Even if it doesn't matter, I am curious, what is causing this?

thank you!

jcmjmp · 10-29-2009, 07:38 PM

Its the tube itself that probably real low to start with. Where did you get your tubes?
The tube store shows the bias rating on the tube base.

txmack · 10-29-2009, 07:40 PM

From Tubes and more .com

It's they have the numbers on the box, I don't know what they were,
never knew exactly what they meant.???

PS-Thanks for quick reply!

txmack · 10-29-2009, 07:41 PM

Should I return them? Does this indicate a problem? I don't know what you mean by real low.

jcmjmp · 10-29-2009, 07:42 PM

I once got a set of tubes labelled 26 for my Jubilee and I couldn't get them in the proper range. I used those in a different amp and ordered a 2nd set. They were labelled to be in the 30s and they biased fine.

txmack · 10-29-2009, 07:48 PM

these were labeled 40 over 4.7 and 40 over 4.8.

Don't know which tube was in which box. What do those numbers mean?

Like I said, I just always set it around 38 or 39 based on reading here and liked the sound, but this doesn't sound shrill or anything...

solarburnDSL50 · 10-29-2009, 09:13 PM

Switch the tubes around and see if you still have the problem.

I want to see if its the tube or the bias pot. It may indicate which...or not.

If its the tube I'd send them back for another set. You should be able to bias them with a greater lower range. 41 is usable but even that will creep up a little more while playing. Did you set the bias and play it for awhile then check it again? You can see where the bias truly is when its at playing temp.

IMO that is in the hot range and the burning tubes up faster range hehe. It is within Marshall's recommended range.

txmack · 10-31-2009, 10:09 AM

Ok, I'll try that, should have occured to me before. And no, I put them in,
set the bias and have had a coupole of rehersals with it, first chance I get I'll fire it up, recheck then switch the tubes and see what that does and report back.

Thanks guys!

solarburnDSL50 · 10-31-2009, 11:04 AM

Quote:

Originally Posted by txmack

Ok, I'll try that, should have occured to me before. And no, I put them in,
set the bias and have had a coupole of rehersals with it, first chance I get I'll fire it up, recheck then switch the tubes and see what that does and report back.

Thanks guys!

Play it for about 10 minutes and have your mm ready to go while you're doing it. Recheck the bias then and see where the bias is at.

10-29-2009, 07:35 PM	#1 (permalink)
txmack Junior Member Join Date: Sep 2009 Location: San Angelo Texas Posts: 8	dsl biasing issue I've never seen before...? Okay, this is my third or fourth DSL 50. I have always set the bias myself, as I have before with this amp. I just got in some new, matched winged c's, popped them in and the left tube will not go lower than 41. I have it turned all the way clockwise to get it there. Other side goes down to 38-39 range just fine, but 41 is the only place I can get them to balance. Sounds good, little loud maybe, but do I have a problem here? Even if it doesn't matter, I am curious, what is causing this? thank you!

10-29-2009, 07:38 PM	#2 (permalink)
jcmjmp Senior Member Join Date: Nov 2008 Posts: 1,341	Re: dsl biasing issue I've never seen before...? Its the tube itself that probably real low to start with. Where did you get your tubes? The tube store shows the bias rating on the tube base.

10-29-2009, 07:40 PM	#3 (permalink)
txmack Junior Member Join Date: Sep 2009 Location: San Angelo Texas Posts: 8	Re: dsl biasing issue I've never seen before...? From Tubes and more .com It's they have the numbers on the box, I don't know what they were, never knew exactly what they meant.??? PS-Thanks for quick reply!

10-29-2009, 07:41 PM	#4 (permalink)
txmack Junior Member Join Date: Sep 2009 Location: San Angelo Texas Posts: 8	Re: dsl biasing issue I've never seen before...? Should I return them? Does this indicate a problem? I don't know what you mean by real low.

10-29-2009, 07:42 PM	#5 (permalink)
jcmjmp Senior Member Join Date: Nov 2008 Posts: 1,341	Re: dsl biasing issue I've never seen before...? I once got a set of tubes labelled 26 for my Jubilee and I couldn't get them in the proper range. I used those in a different amp and ordered a 2nd set. They were labelled to be in the 30s and they biased fine.

10-29-2009, 07:48 PM	#6 (permalink)
txmack Junior Member Join Date: Sep 2009 Location: San Angelo Texas Posts: 8	Re: dsl biasing issue I've never seen before...? these were labeled 40 over 4.7 and 40 over 4.8. Don't know which tube was in which box. What do those numbers mean? Like I said, I just always set it around 38 or 39 based on reading here and liked the sound, but this doesn't sound shrill or anything...

10-31-2009, 10:09 AM	#8 (permalink)
txmack Junior Member Join Date: Sep 2009 Location: San Angelo Texas Posts: 8	Re: dsl biasing issue I've never seen before...? Ok, I'll try that, should have occured to me before. And no, I put them in, set the bias and have had a coupole of rehersals with it, first chance I get I'll fire it up, recheck then switch the tubes and see what that does and report back. Thanks guys!

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