Watts and Ohms and Cabs and Oh My!

[Harley Hexxe]

I guess I misunderstood the question.

Personally, I would have wired up the stereo pairs in parallel to get more punch out of the speakers @4 Ohms per side. Series wiring always seemed to thin to my ears.

   Harley 8)

[Dante]

Thanks Harley, that's what I did to make it a stereo cab...I cut those connections. I soldered them back up and the wires just didn't seem right. Later, I'll put a switch in between those jumpers to make it a stereo/mono cab.

Thanks MJMP, it just seemed weird to me, and I didn't wanna blow shit up ;)

[rnolan]

Hey Dante. Originally it could have been wired either each pair in parallel, then the 2 pairs in series (8 + 8 = 4, then 4 series with 4 = 8) or more likely (as I assume you changed as little of the wiring as you could) the 2 pairs each in series (as per your pic) then the 2 pairs in parallel (8 series 8 = 16, 16 + 16 = 8) , also most quad boxes seem to be wired this way.

If you go with this configuration, you can use one normal jack and one switching jack (like I posted re how I have one of my cabs), or use a switch  .

Depending on the amp(s) you want to use (and particularly if they have SS output stages eg MT100/200) a better wiring IMO (and as Harley suggested) is to parallel each pair (8 + 8 = 4) to get the most from the amp in stereo.  Then series the 2 pairs (4 series 4 = 8) .  So cab then is 8 ohms mono, 4 ohms per side stereo (which is what was asked for in a previous post).  You could do it with a switch or 3 switching jacks. Noting that the SL (switch lugs) connect to the tip (+ve) when no jack inserted

[vansinn]

Just to note As already said, yes, you could withe each speaker set in parallel for a resulting 4 Ohm load - but do pay attention to which output impedance you amp is capable of.
If you amp is solid state, not problem. If it's a tube amp, do make sure to set the impedance selector to 4 Ohm, and if it's fixed 8 Ohm, do not wire the speaker in parallel.

With tube amps, you can always use speaker wirings at higher Ohms than the amp, but never lower, as this could fry the output transformer.

[rnolan]

And to add to what Van is saying (careful), if you use switching jacks the way I've done, you have make sure you only plug into the correct jack or jacks for either mono or stereo operation.

[Dante]

You're all correct!

I had it wired for stereo (8 + 8 = 16 ohms per side) and found myself cranking my MT200 around 3/4...when I usually have it around 1/2 volume. I thought I'd switch it back to 8 ohms mono and simply use a second cab. We'll see how it sounds when I crank it up at practice ;)

Thanks for the help fellas

[vansinn]

But wait! the MT200 has solid state outputs, and does 100 Watts @ 4 Ohm per channel, so you can safely wire your two 8 Ohm speakers [per side] in parallel, for a 4 Ohm load on the amp [per channel].

I don't remember which speakers are in your cab, so dunno how much power they can handle before frying, so go check that out, but else you'll be save - I mean, your speakers.. unless you sit on them as the blow

[Dante]

60w each

100w would be fine....I may rewire it for 4 ohms later

[Harley Hexxe]

I would be curious to hear your review of the sound difference when you re-wire the speaker pairs in parallel and try it that way. Not just the amount of power you have to drive it with, but the difference in the speaker response to your guitar.

    Harley 8)

[Dante]

I would be curious to hear your review of the sound difference when you re-wire the speaker pairs in parallel and try it that way. Not just the amount of power you have to drive it with, but the difference in the speaker response to your guitar.

Me too 

Just for posterity; I'd basically be doing this on each side of the 4x12:

[Harley Hexxe]

Yes, exactly

[MarshallJMP]

Yep correct!

[Kim]

I concur.   ;)

[vansinn]

I shall upon hearing the results..

[Dante]

Okay...while I have not tried the 4 ohms per side wiring yet, I finally tested the stock setup (8 ohms mono). I also hooked my 1x12 Thiele cab up to channel B, so I could compare. Honestly, and happily, there isn't a lot of difference between the cabs' sounds...they're both pretty transparent I guess. Of course, I'm in a bedroom, only about half as loud as a gig. I'll bring both cabs to practice next Friday night. They sure sound awesome - of course, they're on opposite sides of the room, so it sounds really big  :banana-rock:

Running the 4x12 cab mono, without the other speaker, it sounds clearer and cleaner to my ears than running stereo. I have never been a fan of running a single box in stereo. I put a wall in my old Carvin cab for this reason (& made it heavier  ) My feeling is the sides should be in separate cabs. I'll hook up a switch later to split / join the 4x12, but I'm good for now

Until I get it all done, I'll just bring two cabs when the sound system allows, otherwise I'm running mono anyway