Matchless DC30 half power switch question

tedwoods

Member
Messages
680
I usually run my DC30 at the half power switch setting.
This supposedly disengages two of the power tubes(?).

Is it possible to determine which ones,middle two or the ones on both sides or some other combination,and more importantly is it then possible not to have any tubes at all at the unused positions without any adverse effects to the amp or sound?

Thanks,

Ted
 

drbob1

Gold Supporting Member
Messages
28,595
I'm not sure about the DC30, most amps that do this use either the inner or outer pair. You wouldn't hurt the amp by pulling one or the other and seeing which made the sound go away (of course, turn the amp OFF before removing tubes). There's not much advantage to not having the tubes in the unused positions but it should be safe (unless the heaters are in series, which I doubt).
 

tedwoods

Member
Messages
680
Thanks!

I was thinking that if I use the amp in half power(2 tubes on) , when I do decide to use it at full power the rest of the tubes might not be matched anymore since they remain unused.

So,I figured it would be best to keep a set of two for dedicated half power use and a set of four for full power.

I believe some people use to "share" tube duties,swapping the two used with the two unused pairs everytime they play, but I figured two different sets would be more practical.

I also wanted to make sure no extra strain is placed on the components...

Ted
 

Kiwi

Silver Supporting Member
Messages
4,081
I'm pretty sure it's the inner two that get used at half power, but here's the easy way to tell:

In a darkened room, warm it up on Standby on half power. Then flip the amp to Power On. Two tubes should light up with the blue glow. Those are the "hot" ones.

I play at half power a lot. I rotate the two "used"tubes every six months or so to try to even out the wear. Who knows if it's worth the effort, since modern EL84s are not expensive.

Kiwi
 

Swarty

Member
Messages
1,131
Another thought is to touch them after the amp has been on for awhile. The tubes being used will be too hot to touch.
 

tedwoods

Member
Messages
680
Thanks guys!

It also occured to me that since I use only two I could then also use some Brimars that I had found...
Trouble is,I've only found two matched duets that can't be used together...so that's the rest of the story!

Ted
 

TheAmpNerd

Member
Messages
1,056
Originally posted by tedwoods
Thanks guys!

It also occured to me that since I use only two I could then also use some Brimars that I had found...
Trouble is,I've only found two matched duets that can't be used together...so that's the rest of the story!

Ted
Ted,

Sure you can. Use one duet for the inner,
and the other duet for the outer.

Then, each pair is matched. That actually
might sound very good, you might like it.
 




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