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GMC Forum _ GEAR & PRODUCTION _ Quick Question About Ohm-matching

Posted by: Xuestor Jun 23 2008, 04:50 PM

I've got a Hughes & Kettner Switchblade head and recently I got a hold of a REALLY cheap 2*12 cab with 8ohms in mono, or 16 ohms in stereo.

When I was supposed to connect the cab to my amp, I just got this feeling, and had to double check this with someone with more knowledge than me in this smile.gif

The amp has these connectors : 1*4ohm, 1*8ohm, 2*16ohm. What will my options be here? My first thought was just to plug it in the 1*8ohms output, since the amp is a mono amp, right? But will this mean that I also can connect it to the 2 16ohms outputs aswell? (just that I wont get the stereo effect out of the cab)

MickeM - Your knowledge is very appreciated on this one! smile.gif

Posted by: Ivan Milenkovic Jun 23 2008, 05:01 PM

2x16Ohm option on the amp is for connecting 2 cabs or 2 sets of speakers rated at 16Ohm. No worries mate, just dial in 1x8Ohm, and you don't have anything to worry about. wink.gif

Posted by: MickeM Jun 23 2008, 06:27 PM

With two amps or a stereo power amp one could drive it in stereo. Remember to se the switch to stereo if there is one.

But in your case, just to plug 8Ohm -> 8Ohm

If you get an extra cabinet you can connect
16Ohm amp - > 16Ohm cabinet#1
16Ohm amp - > 16Ohm cabinet#2

All this is sensitive stuff so read up on your amp to make sure what works, details can differ from brand to brand. I havn't read up on the Switchblade to be hones, I keep one 4x12 cab connected and that's it mellow.gif

Posted by: MickeM Jun 23 2008, 06:57 PM

I should add, if you're cab has the stereo switch that would probably mean the speakers run parallell when in stereo and you could connect a stereo amp
16 -> 16 Left
16 -> 16 Right

and get stereo sound.

Poweramps would usually say like 2x50W to state it's got stereo output.

Posted by: Xuestor Jun 23 2008, 08:13 PM

QUOTE (MickeM @ Jun 23 2008, 07:57 PM) *
I should add, if you're cab has the stereo switch that would probably mean the speakers run parallell when in stereo and you could connect a stereo amp
16 -> 16 Left
16 -> 16 Right

and get stereo sound.

Poweramps would usually say like 2x50W to state it's got stereo output.



Ok, thanks for the info!

I now has the cab connected as mono to the 8ohm amp-output. But would it be possible to use the 2*16 ohms output on the amp, switch the cab to stereo and use it like that? Wouldn't that be just as running 2 separate cabs, just that it doesnt get the stereo sound (for FX and stuff)? Or would this damage the amp?

Posted by: Henry Dietzel Jun 23 2008, 08:20 PM

This has always been a semi-confusing topic for me also

Posted by: Ivan Milenkovic Jun 23 2008, 08:36 PM

Well you have to check with the manual of teh amp and see if it gives away stereo signal. You already said it is mono, so 2x16Ohm is simply for adding more mono cabs (2 mono cabs to be precise)

Posted by: MickeM Jun 23 2008, 08:41 PM

QUOTE (Xuestor @ Jun 23 2008, 09:13 PM) *
Ok, thanks for the info!

I now has the cab connected as mono to the 8ohm amp-output. But would it be possible to use the 2*16 ohms output on the amp, switch the cab to stereo and use it like that? Wouldn't that be just as running 2 separate cabs, just that it doesnt get the stereo sound (for FX and stuff)? Or would this damage the amp?

I really want someone to second this before you run off with these settings. unsure.gif

I'm saying that should work. But there's no use really, I never tried that myself but in my world I'm striving to run on 4 Ohm rather than 8 Ohm, the lower Ohm rather the better since it "breaks" the amp less.
If you think of it (and I feel I'm out on a limb here trying to explain...) as a flood gate, at 16 Ohm the water is barely comming through, at 8 Ohm it's half open, at 4 Ohm it's close to fully open and the watter floods through.
So as I see it running at 2x16Ohm gives no benefit at all. Two 16 Ohm cabinets equals one 8 Ohm in regards to "flood gate water masses".


And besides... I think this Ohm business is a mess and I can't guarantee everything or even anything I said is true. I sometimes wish Mr Ohm had an interest for squrrels rather than electricity so we didn't have to bother about all of this laugh.gif

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