I was wondering if anyone has tested 4x12 cabs at 16ohm vs 8ohm's?I have 2 4x12's,one I'm going for totall vintage vibe(2 greenback 25's,and 2 30h's,probably end up with Scumbacks,or heritage),the other cab I'm going for huge modern tone.(at times VERY heavy Slipknot,Pantera,Korn)Sub low end,and tight.(2 75's and 2 V30's).I've noticed that most modern cabs(Uberschall cab,Diezal,Mesa recto,Marshall Mode 4,etc),run at 8 ohm's. So,what is the difference in tone with cab wired at 8ohm's?

You'll get a slightly deeper and fuller sound at 8. It also makes a difference how the cab is wired - for heavy tones, you're better with two parallel pairs in series than two series pairs in parallel. If you're only going to run one cab at a time, I'd even go further and make a 4-ohm all-parallel cab, using 16-ohm speakers. (The reason Marshall Mode 4s run at 8 ohms is because they're solid-state BTW - two 8-ohm cabs makes 4 ohms, which is the normal minimum impedance for a solid-state amp, and gives the most power - probably not specifically for tone. Standard modern Marshall cabs are switchable between 16 and 4.)

Thanks john. Do you know where to get those different wireing diagrams? Also,do you have any input on front loaded speakers vs. rear loaded? Thanks.

Ok...Can you show me how the " two parallel pairs in series" is wired?! I have heard this before, but I have no clue!! Thanx, keith

Starting with four speakers in a cab and no wires... there should be two pairs of speakers where the connection tags are pointing at each other. Call these pairs A and B, and the individual speakers A1, A2, B1 and B2. First, for each of these pairs, connect the positive terminals together, and the negative terminals together - four wires in total. A1+ to A2+, A1- to A2-, B1+ to B2+, B1- to B2- Then, connect the positive terminals of one pair to the negative terminals of the other - one wire. B1+ to A1-, or B2+ to A2- (it doesn't matter which). Finally, connect the positive wire from the jack (tip connection) to the positive, and the negative wire from the jack (sleeve connection) to the negative, that you didn't use in the last step: J+ to A1+ (or A2+), and J- to B1- (or B2-). Total of 7 wires - one more than for two series pairs in parallel, so you may need an extra wire.

..........................pos..........neg .......................... +.............- ..speaker} +.................................- { speaker ...A1.......}.......................................{....A2 .............} -..................................+ { ..speaker} +..................................- { speaker ....B1......}.......................................{....B2 .............} -..................................+ { Sorry... I need pics, John... You just join A1 with A2 - criss cross neg to neg, pos to pos... same with B1 AND B2... Then I could join B1- to B2+ Then last, A1+ to positive (cab input) and A2 - to negative (cab input) This right, John? Thanx!!! Keith

Yes No... A1- to B1+ A1+ to input+ and B1- to input- Your pic is right - just think of the signal as going to the top of the top pair, passing down through that pair, then going down to the top of the lower pair, through that, then back to the jack.

Ok, Thanx John! And this will give a "heavier" tone you say? If you don't mind, what are the differences I'll hear? I have a couple of Bogner 4x12's and I'm almost positive that they are NOT wired this way. So, I'll have to try it. Keith

I think it gives a slightly deeper and more solid tone - but it's not a huge difference. If you've got a cab already, and it's wired two-series-pairs-in-parallel, you can easily test the difference with one extra wire. There should be two 'single' wires going between two pairs of the speakers - these are the series connections. Connect them together (at either end), and you now have a two-parallel-pairs-in-series cab .

I dropped my marshall cab from 16 down to 4 ohms and didn't notice any increased bass. I prefer using the extra windings on the OT, running a 16 ohm cabinet.

I have one of those modern Marshall 4x12 with the stereo jack switch. Anyway it also has two jacks that when used in mono one is 4 ohm and one is 16 ohm so one day I switched back and forth and found the 4 ohm to sound ever so slightly deeper. I also tried with a buddy of mine playing and I switched the cable he too said he heard the 4 ohm to be deeper. Not very scientific but it did sound different to us. My other cabs are wired to 16 ohms with two parallel pairs in series. Unfortunately it takes so long to make the change that there is no way I would swear there is a difference. I have thought about rewiring them to 4 ohms

Ya... I love tweaking and trying out all kinds of amps as much as anyone, but rewiring cabs is just a complete pain in the arse in my opinion! Keith

I just re-wired my UberKab and.... 16 ohms - more vintage-y, looser feel, notes have bloom 4 ohms - tighter, more immediate, faster attack, stiff feel This is assuming you set the amp at 16 for a 16 ohm cab and at 4 for a 4 ohm cab. Mismatching imepedence changes everything!