New Rig

[warswr]

Hey guys i've been looking around the forums for awhile but finally have a questions to ask myself.

I just got a new amp head (SWR SM 500) and it sounds stellar, probably the best amp i've ever heard. Some stats on it:

# Bridged mono: 500W @ 4 ohms, 400W @ 8 ohms, 250W @ 16 ohms (minimum load 4 ohms)
# Stereo: 300W per side @ 2 ohms, 250W @ 4 ohms, 150W @ 8 ohms (minimum load 2 ohms)

Currently im running it into an Ashdown 4x10 rated at 450W continuous power handling (8 ohms)

So the amp and this cab as of now fit pretty well together. However I was looking for get some more headroom for it, increase the quality a little when i want to get LOUD. I was thinking about buying an Ashdown 2x10, 8 ohms, with 200W continuous. Would this give me a little more headroom (im still pretty new to the whole amp game)? The ohms would drop to 4 ohms, and more speakers would mean more volume so possibly not having to run the main volume all the way up? Im not sure on any of this, but anything would help!

Thanks, Will Myers

 

[JacksonsMen]

that would knock it down to 4ohms at 650w continuous. so yes, that will give you the headroom you want

 

[JacksonsMen]

welcome to talkbass btw

 

[warswr]

thank you very much!

if you could do me one further favor and explain how you figured that out i would really appreciate it.

 

[JacksonsMen]

im a bit rusty here so if my math is off someone help me. but you take the two loads 8ohm and 8ohm and it equals 4ohms, two 4ohms equal 2ohm. i cant remember exactly why, but when you figure what ohms stand for (impedance in the circut line) it makes sense.

as far as the wattage, just add them together, but be sure your adding RMS and RMS not RMS and peak wattage

if that doesnt make any sense let me know, im a bit tired over here

 

[markjazzbassist]

that makes sense. your math is correct. you could run your rig in stereo too. i don't know how to do the math on that though.

 

[JacksonsMen]

stereo doesnt cut down on the ohms per load though, two get the ohm load to reduce it all has to be in the same signal chain

 

[davidmurphy]

I can't reallly see a way to get more headroom on your 4x10.
At moment you're running 400W bridged (I assume) into a 450W cab.
If you add the 2nd cab you could:

A) Run both cabs in stereo @ 8 Ohms.
This would put 150W into each cab which leaves no headroom.

B) Run both cabs, in parallel, bridged @ 4 Ohms.
This would split 500W evenly between the 2 giving 250W into your 450W 4x10 leaving no headroom & 250W into your 200W 2x10.

The addition of a 2nd cab, while not fiving any more headroom, might fill out the sound enough to keep you happy. Possibly a 1x15 instead?

Read Ivan Mike's 'Ohms FAQ'. It'll help you figure out how to calculate Ohm loads, especially on trickier 4 Ohm & 8 Ohm cab combinations.

As always I'm open to correction but to the best of my knowledge this is true.


P.s. Be careful running the 400 W briged @ 8 Ohms into your 450W 4x10. The 450W is the amount of clean power the cab can handle. If you have your amp all the way up it's probably clipping which would be sending much more power into the speaker (check the peak rms on the amp).
Also, if it's constantly clipping the distorted signal is bad for the speaker.

Then what happens is the speaker blows, you'll post a thread asking about 'underpowering' a speaker, Bill Fitzmaurice will get involved & it'll all turn nasty...................

 

[warswr]

would adding a power amp to my rig help any? If so what would be a good priced one to get the job done?

 

[davidmurphy]

You could sell the head you have, buy whatever preamp is in it seperately (as you love the sound so much) & then buy a kick ass power amp.
Can't advise you on prices as I'm in Ireland.

Do a search on power amps. QSC, Crest, Crown, etc, are all good.
Keep checking Ebay & make sure you check the specs at the official website of the maker before you bid.