combining speakers of different sizes

[Bluefinger]

Hi,

What are your thoughts on this? I am considering to build an amp with different sized speakers. Maybe something like a 1x12" plus 2x8". The two 8 inchers together have roughly the same speaker surface as the single 12. So I wonder if I should use three speakers with the same impedance? What about using two 16ohms 8" speakers and one 8ohms 12" speaker? If I would wire them in parallell this would result in 4ohms all together and the two 8inchers should get the same amount of signal together as the 12incher. Would that make sense???

thanks
BF

BTW: Happy new year!!!!!

[riz]

I think it makes sense. I myself might like 10s better than 8s but that's me. But if you already have the 8s laying around... Won't know till ya try.

[Ken Moon]

As riz said, try it for yourself and see - a lot depends on the cab design, and the efficiency of the chosen speakers.

I've built several vertical combo amps, with an open-back 12" speaker on the bottom and a sealed 10" on the top - the trick is to find an efficient enough 12 incher to keep up with the 10 - I know that sounds backwards, but it has a lot to do with the cab design in my case (the top half is angled and the bottom half straight).

When I'm trying new cab setups and speakers, I like to buy used speakers on eBay or amp forums, so I can sell the ones I don't like for at least close to what I paid - I've only bought one bad speaker this way out of maybe 50 or 60 speakers over the years.

[ThermionicScott]

There were some Gibson and various organ amps that mixed 8" and 12" speakers to get a particular frequency response. In addition to making sure one speaker doesn't get overburdened, you'll want to make sure they're all in-phase.

Do you have the 16-ohm 8" speakers on hand? Seems like those would be kind of rare.

- Scott

[Bluefinger]

The amp I am talking about is supposed to be a harp amp and I like both the characteristics of 8" and 12" speaker. In my head it sounds like a good combination. I have no idea if it really works out in the real world.

I don't have the 8 inchers on hand but Weber can build them anyway you want so that's not the problem.

I am still not sure if it would be better to use same size speakers ... I just want to try something different.

[jfutral]

I knew a guy once who used an old Peavy tower PA cabinet with his amp head (I can't remember which amp it was). He removed the crossover and tweeter, plugged the hole, and put in a JBL 8" and some old Celestion 12". It sounded AWESOME! As much as I like odd-ball, quirky things that add individuality, this was more than I am willing to try. So, go for it! What's the worst that can happen? You don't like the sound?

Joe

[allende]

I'm curious how this works out for you. I'm in the initial stages of building a 5E7-based harp amp, and I'm planning on using speakers I have on hand, a 12" alnico and 2 8" ceramics. I have a theory that mixing speakers with different characteristics, esp size, might help to control feedback in a harp amp--since feedback, when it occurs, seems to be at a specific frequency, mixing speakers with different tonal profiles might minimize this. Just a theory, but as I said, I'm curious about your experience.

[Bluefinger]

I'll report back as soon as I have it. This should be in a week or two. The amp itself is almost done. Its a 5E7/5F4 style preamp with a 5F6A PI and power section. Cconnecting that amp to my 5F4 cab shows that this is a great combo for harp. Although the 5F4 if already great that PI gives me a tighter punch and more definition. I also used higher plate voltages and that really is an improvement. I'll try to do some sound or video clips ASAP ...