REALLY n00b question

[Nadz1lla]

About amp speakers: This might be a face-palm moment for most of you, but I'm just one of those guys who doesn't know stuff until he needs to, and then he goes to find out.  :)

If I wanted to build a 2x12, could I have two completely different speaker types in it? Say a Celestion of 50w and an Eminence of 150w... would the power just be shared equally between them or would it put strain on the lower wattage cone etc?

What kind of stuff do I need to know in order to make a cab that works and won't bust itself, heh.  :lol:

[ericsabbath]

you would have a 100w cab
the 150w speaker would handle more abuse, though, but the 50w won't be pushed harder than it already would with a matched pair

[JDC]

what he said, always go by the smallest watt speaker then multiple by number of speakers, so ye 50w x 2 = 100w is the most it'll handle

[Frank]

Current (and therefore power) divides between the two speaker loads equally if they are the same impedance. The power handling capacity is just a maximum rating per speaker so if you've got 100 Watts dividing between two speakers then one will radiate 50 Watts and so will the other.

[Toe-Knee]

Current (and therefore power) divides between the two speaker loads equally if they are the same impedance. The power handling capacity is just a maximum rating per speaker so if you've got 100 Watts dividing between two speakers then one will radiate 50 Watts and so will the other.

I always look forward to your posts! It's refreshing to see more technical answers rather than do this itll work!

[Nadz1lla]

Thanks guys, that's what I was edging towards but needed confirmation, heh.

I'm thinking of building a cab at some point, probably just a 2x12, but I wanted to research mixing two types of speaker, like a greenback and a swamp thang or something. I need to research how different speakers sound, first, but I like the idea of double-micing the cab for recording and having two different tones coming through for mixing.

So yeah, thanks for the info! Need to research impedance, too, I guess, hah!  :D

[Alex]

Impedance - check out the celestion webpage. Speakers should always be of the same impedance rating in a cab, otherwise you end up with very odd impedances.

Also, the cab should always be able to handle a bit more than what the nominal amp rating is, to ensure you won't accidentally damage the speakers. So for a 100Watt top, it's better to use a cab that can at least withstand 150Watts.
Eminence makes some nice speakers that are similar to Celestion classics, but have higher power ratings, in particular the Wizard, which is similar in tone to the G12 H30.

[sgmypod]

Just make sure both the same ohmage

[Frank]

Just make sure both the same ohmage

This is an important point, unless you want something like a 5.333 ohm cabinet!

Two 16 ohm speakers in parallel = 8 ohm cabinet
Two 8 ohm speakers in series = 16 ohm cabinet
Two 8 ohm speakers in parallel = 4 ohm cabinet
Two 4 ohm speakers in series = 8 ohm cabinet

I'd avoid series wiring, if one speaker fails then there will be no load connected to your amp and that spells trouble.

[BigB]

Also, the cab should always be able to handle a bit more than what the nominal amp rating is

Explanation: the nominal amp rating is (supposed to be) average (RMS) power *before* breakup. The real maximum power that can be delivered by a valve amp (peak power, amp full cranked) can rate as far as two times the nominal power, depending on the exact circuit, valves, bias settings and whatnot - and of course the delta between the (usually optimistic) official nominal power rating and the real power rating you'd get using an oscilloscope ;)

OTHO and from what I've read here and there (please someone correct me if I'm wrong), speakers builders tend to be rather conservative wrt/ official power handling rating, so a speaker rated for 50W can usually take quite some more peak power (but will not endure it for a long time), so yes, +50% is probably enough for most cases but definitly not too much of a security margin (some would suggest +100% to be safe).

[dave_mc]

just bear in mind that randomly combining speakers might not sound any good :lol:

there are tried and tested combos which do sound good- if you don't know what you're doing i'd probably stick to those (or at very least, email the speaker company to see if the combo you're thinking of will work).

[JDC]

If you're thinking of micing up the cab just be aware the sound of the room might not be ideal for recording

[Nadz1lla]

Cheers for all the info guys! I have a lot of research to get on with, methinks!   :lol:

Thanks!

[Lucifuge]

AFAIK, it's generally a good idea to use two speakers that are fairly close in sensitivity/efficiency, otherwise the overall sound will be dominated by the more efficient speaker and the other won't have much effect.