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Speaker protection attentuator

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Sirion:
Okay, here comes an unusual question, that will demand some explanation. I run an MP-1 with a Marshall 9040 solid state amp. After having tried some different speakers I have come to the conclusion that I love everything about the regular Celestion Greenbacks… except the 25 watt rating. The speakers really come to their own when they are really being pushed, but since a little bit of extra headroom is advisable with solid state power amps, one runs the risk of running them too hard. Therefore: are there any devices out there that can either attenuate the signal before it reaches the speakers, if its power exceeds a certain limit? or something that at least could give a warning?

rnolan:
Hey Sirion, the idea of headroom in the amp(s) compared to speaker power handling is more suited to PA AND you need to know what you are doing (and generally you have a compressor set to peak limit before the amps). Comparatively, distorted guitar is very compressed(ish) and better (IMHO) to have a bit more speaker capacity than amp, not that you can't do it, just have to be careful not to pop speakers  :facepalm: .  It doesn't help that the 9040 has no vol knobs... So you choices are to:
control it with speaker impedance and/and numbers of (25w) speakers
use a compressor/peak limiter before the amp
use a power soak between amp and speakers (I have a Tom Shultz power soak I use with my 73 Marshall 50, not for the speakers though, just so I can be in the same room  >:D )

To do it with speakers, depends how many 25w greenbacks you have per channel and their impedance.  IIRC the Marshall can deliver 120w p/ch into 4 ohms but will be less into 8 or less again into 16 ohms.
So Ideally give it a 8 ohm load with 4 x 25s, nice and safe (but that's 2 quad boxes)
or 16 ohm load, and 2 x 25 w greeenies (p/ch) and be a "bit" careful how high you turn up the input to the amp.
It will also be ok at 8 ohms, but you need to be even more careful

rnolan:
Another thought, you can put a fuse in the speaker box, there used to be this great PA bible book that had the correct fuse ratings, maybe MJMP can tell you the right value fuses to use ? Or maybe these days there are circuit breakers you can use for the same job  :dunno: .

And you "could say" run just 1 x 25 w 16 ohm per side, it will sound f**king awesome  >:D , but popping a speaker becomes a real likely hood (as I found out when I was 14...crap it sounded so good though (well up to the point where there was no sound LoL), that was with Philips 12" twin cone 20w hifi speakers, my dad was not impressed  :facepalm: ).

MarshallJMP:
Mmmm using a fuse to protect your speakers isn't such a good idea IMO. Maybe use a limiter between preamp and poweramp?

vansinn:
I agree on not using a fuse for protection; it'll easily slow-down your attack.
As you amp has no master volume control, a simple voltage divide could be installed, set to limit the max power the amp can produce.

Else, as has been suggested, use a limiter. I'll object to using a compressor; you'll want to only limit the too hot peaks.

Check my short story on the Gemini compressor/limiter; it's pretty neat, and can be set to hardly be noticeable or to outright do something to the sound, should you fancy..

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