4x12 with different speakers

[suprstar]

It's time to perfect my guitar tone, so I bought some celestion vintage 30's, I want to replace 2 of the 4 speakers in my 4x12 cab with them. The cab is a Peavey MS412 with sheffield's if it matters. All the speakers are 16 ohms, is there anything else I need to consider?

It's a stereo cab, so I'm thinking of putting 2 v30's on one input and the 2 stock speakers on the other. Currently, it can be switched to mono to run all 4 speakers at 16 ohms. Would it be better to wire it up to 4 ohm mono instead?

I've read up about the X pattern for mixing and matching speakers, what makes that any better than doing left/right or top/bottom pairs?

Any suggestions or opinions? I'm doing this mostly for the purpose of close-mic'ing with 57's, so I have 2 tonally different tracks of the same performance. I'm not in a band now, but that could change any time, so the cab could end up on stage again eventually.

edit: I'd like to add that I'd be pushing this cab with either a crate solid state 140w head into all 4 speakers. or an epi valve jr 5w tube head into 2.

[gcapel]

If it is indeed a stereo cab, it should have a switch somehow to isolate the two sides in the 8 ohm format. If that is the case then use the same wiring configuration. You just want to use the 8 ohm output from the two amps.

Remember divide if wired paralled, and multiply if wired in series.

As far as speaker placement: I would for sure put the V30s in the top. They will sound better in the room.

[R!ck]

I'd definatly agree with gcapel in relation the V30's, although at this stage you're only close miking with cardioids leave room to adapt your mic choices. If you put the V30's at the top I think you'll be pleasantly surprised by the brightness of some of the reflections you'll pick up with even a reasonably dull room mic.

As for the wiring, i'm not entirely clear on the reasoning behind the x pattern, it would be interesting to find out actually if anyone can shed some more light on the matter.

[gcapel]

wow i spent too much time drawing this but here is an illustration of how a stock marshall 1960 cab is wired mono and stereo.

[gcapel]

Originally Posted by soundchaser59

I would think you dont want a huge difference in power ratings between the Sheffields and the V30s. For example, if you put two 10 watt speakers in with two 50 watt speakers, then you would never be wise to use an amp rated at more than 20 watts. The amp won't know that two of the speakers cant handle as much power as the other two speakers.

I agree, if the sheifields are rated lower in wattage then v30 then they will be driven more and you wouldn't get the most out of the v30.s. If I were you I would gut the shefields and put the v30's in one side until you could get two more. You still have to keep in mind your amp wattage and speaker wattage differences.

[ggunn]

Originally Posted by suprstar

Currently, it can be switched to mono to run all 4 speakers at 16 ohms. Would it be better to wire it up to 4 ohm mono instead?

It depends on your amp. Does it prefer a 4 or 16 ohm load? If it's a tube amp and wants an 8 ohm load, it's probably safer to wire it up as 16 rather than 4. If it's SS, then it probably doesn't make any diff, except that you'll get more power from the amp at 4 ohms.

[suprstar]

Yep it's definately stereo, and there is a switch. I'll probably end up trying the speakers in various positions within the cab, I assume that'd affect how it sounds to the player more than the 57's up in the cones.

The sheffields and v30's are close in power handling capability, my amp won't blow them. I'm hoping the sensitivities are similar, so there aren't 2 loud speakers and 2 quiet ones..

As far as 4/16 ohm mono goes, I suppose it doesn't matter for now. The crate has 2 outputs that push 70w into each channel at 8 ohms, so that's how I'd connect that. The valve junior has 3 outputs on the back for 4, 8, and 16ohm cab's, so it won't hurt the amp regardless how it's wired. For that amp, I'll probably just run it to 2 speakers anyway (at 8 ohms) anyway. It's not strong enough to push 4 speakers, or even 2 for that matter... I'm in the market for a new head though, so it might matter in the future. I could always re-wire it then.

Does anything about cab impedance affect the tone?

I actually have two of these cab's, and enough speakers to try any config I want, including loading one up with ALL v30's, which I want to do anyway to A/B the speakers. So I'll be experimenting with it.

[soundchaser59]

I would think you dont want a huge difference in power ratings between the Sheffields and the V30s. For example, if you put two 10 watt speakers in with two 50 watt speakers, then you would never be wise to use an amp rated at more than 20 watts. The amp won't know that two of the speakers cant handle as much power as the other two speakers.