RedDavid

Eylo. First post, eeeh.

My theory is, it should be possible to half the volume output of the DSL100 going into a 1960A cab by connecting two speaker cables to the parallel outputs, connecing them to the left and right inputs of 1960A cab, and setting the impedance of the parallel to 4ohms. With the cab set to stereo, it will have an impedance of 8 ohms per speaker pair (16 ohm total), double the impedance expected by the amp. This should half the volume.

Does my (weak) understanding of amp physics serve me well here, or is this theory an awful failure of logic that will go horribly, horribly wrong if I try it?

steelhorse

Why not just get an attenuator?

steelhorse

Welcome to the forum btw!

Brett Blackmore

Hi RedDavid,

Your points on the setup are correct but I do not believe it will lower the volume or let the amp crank up earlier at the same volume. There was another guitarist in my rehearsal room who did exactly what you have said - yet I never heard any difference - he claimed it "breaks up earlier at a lower volume" but to me it was the same which is why I never ever bothered to try it out.

As far as I know there is no difference - the amp is designed to give the same volume but at different impedances.

Cheers Brett

Adwex

Welcome to the forum. I'm sorry to tell you that there are several failures of logic in your theory....

- Doubling the impedance will not halve the power, it will put a great deal of stress on the output transformer, and it could fail.

- Impedances in parallel do not add like they do in series, they combine like this:
1/Rtotal = 1/R1 +1/R2
so connecting in parallel both sides of your stereo cab at 8 ohms each side, the resulting impedance will be 4 ohms, not 16.

- Using 2 cables coming from the parallel outputs on the amp into the stereo cab, is the same exact thing as using 1 cable into a mono cab. The DSL 100 is not stereo, all you would be doing is wasting a cable.

- You always want to match the impedance of the cab and amp. Always!!!!

- To do what you want, you need an attenuator.

__________________
www.myspace.com/rockerlivemusic

steelhorse

heh, great info Adwex, and you came to the same conclusion as I did, get an attenuator.

fwiw that's what I love about the TSL, the VPR or virtual power reduction that drops it to around 45watts. Great sound, great idea!

I love how the 2555 does this too, sounds fantastic! But you already knew that!

Adwex

I never use the 1/2 power switch on my 2555. Tried it once or twice, sounded "thin", lost bottom end.

__________________
www.myspace.com/rockerlivemusic

RachelMorgan

Halving the volume of a 100 watt amp means reducing it to 10 watts or the equivalent. The best way is to use an attenuator and it requires less thinking. I'm bad at math so my brain flatlined at those equations.

__________________
Guitars: ESP LTD Alexi-600 V; Gibson SG Standard; Schecter C-1 Hellraiser (JB/'59 w/ JB coil tap)
Amps: Peavey 6505+; Fender HR Deville.
Board: Crybaby -> TS808 -> amp -> M-108 -> Whammy -> BF-3 -> DD-6 -> Sonic Stomp -> amp -> Hot Plate ->
Speakers: Avatar Contemporary 212s #1: Greenbacks; #2: Vintage 30s

big dooley

halving the volume on a DSL100 head?
very simple..

there are some pots on the facepanel...
take the 7th and 9th and turn them anti-clockwise....


bingo!!!!

steelhorse

The 2555 I had sounded amazing at half power with a nice bottom end. I don't think the point for me using it was to make it quieter, but make it more soulful which the way I set it up seemed to do quite nicely.

What tubes you have in yours?

Stretchy

DAMN!!!! IT WORKS!!!!!!

__________________
SG400
LP Standard
DSL 100

mmorse

I've owned 3 amps with a half power switch including a 2550. All simply switch the power tubes from Pentode to Triode. Not the best way to go about it but it's a cheap and easy way to half the power.

All three did the same thing. Only dropped overall volume by 3db and the tone thinned out considerably. Total waste IMO.

Adwex

I have SED Winged =C= EL34's, and a mix of Groove Tube and Tung Sol pre's. To be honest, I haven't touched that switch in a year. Maybe I'll give it another try, but I'm not optimistic.

__________________
www.myspace.com/rockerlivemusic

steelhorse

I'm sure the way you play and have it setup is fine bro. For me the half power mod had to be tweaked on the amp and with the guitar but I was able to great tones from it.

I loved Winged C's. Great tube.

The tubes in the 2555 when I had it was all original stock.

__________________
"Man who says it cannot be done, should not interrupt man who is doing it!"