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Half power switch on 6505/6505+/6534+

Posted: Wed Jun 26, 2013 7:50 pm
by Agent Orange
How hard is it to add a switch to shut down two power tubes (i.e., a pair, the two outer or two inner ones) on the 6505 series of amplifiers so that the output is 60W? This would seem like a really useful mod. There would only need to be a rocker switch on the back of the amp as far as controls go, as you don't change this on the fly. Partly I am wondering why Peavey has never included it, but I am also wondering if a mod like that would void the factory warranty on the rest of the components.

Re: Half power switch on 6505/6505+/6534+

Posted: Wed Jun 26, 2013 8:19 pm
by Enzo
The warranty is not on each part, it is on the unit as a whole. If a part goes bad and renders the amp defective, we replace the part under warranty. If there are 400 parts in the amp, there are not 400 warranties. You can't void part of the warranty and keep the rest.

As a warranty repair tech, it is up to me to decide when I see it. SO if I see some mod like that in an amp, and it appears well done, and does not seem to be involved with the problem, I might ignore it. I might not.

Just my opinion, but the main usefulness of a half-power switch is in marketing the amp. Otherwise, I don't see a lot of use for it. The volume reduction is only 3 decibels, maybe less if the B+ rises under the reduced load. Might be a little easier to break up the remaining power tubes if you are going for that, but mainly you lose headroom.

As to why they didn't add one, I suspect the added cost would not be made up in increased sales. They'd have to design a new power tube board and make it, plus make room on the panel for the switch and wire it. Or maybe do it with relays.

WHen you pull tubes, you also SHOULD change the impedance tap used for the speakers. I don't think it matters much, as no one I know who has a half-power switch bothers doing so.

Re: Half power switch on 6505/6505+/6534+

Posted: Wed Jun 26, 2013 8:50 pm
by Sadistic_sponge
I agree with Enzo's comments though I have a much less informed perspective. The fundamental issue here is that cutting the wattage in half really isn't going to do much to reduce volume/ increase saturation. A 5 watt amp can stilll blow your brains out when cranked and hooked up to a good speaker. It's still gonna be a 6505, it's still gonna be loud as a mother. If volume reduction and increase saturation is the goal then the "mod" you might want to think about is an attenuator of some sort, or perhaps building in a PPIMV or similar master volume mod, which would definitely void your warranty.

Re: Half power switch on 6505/6505+/6534+

Posted: Wed Jun 26, 2013 9:46 pm
by Agent Orange
Thanks, I was just curious about it. I know that most of the people I know with amps from this series almost never turn the volume past half way.

Re: Half power switch on 6505/6505+/6534+

Posted: Fri Jun 28, 2013 8:15 am
by lovesacdc
I pulled 2 of my tubes and dropped the ohms to 8 ohms into my 16 ohm cab. I like the sound better this way.

Re: Half power switch on 6505/6505+/6534+

Posted: Fri Jun 28, 2013 10:31 am
by Enzo
Thing is that most people run most amps at less than full up. Classic 30 for example, I don't see them running with the controls maxed.

Re: Half power switch on 6505/6505+/6534+

Posted: Fri Jun 28, 2013 3:42 pm
by Van Noord
The 6505 doesn't get any louder past half on the post dial anyways. You just end up distorting the powertubes and the sound get muddy and unfocused.
Not an issue though, because a 6505 at half on the volume is just as loud as a lot of amps set to 8-9.