Two amps to one sub???

frugmonkey · 09-12-2006, 12:28 PM

it might be a stupid question, but if you use a dual voice coil sub is it possible to connect two identical amps, one to each coil, and have them both set up exactly the same?

has it been done before, or is it just a silly idea?

bes51659 · 09-12-2006, 12:40 PM

Quite possible. But even better is to combine bass from both left and right in one speaker without haveing a filter to get a center bass.

bes51659 · 09-12-2006, 12:44 PM

With two voice coils you get all kind of possibilities.

You can connect them in parallell to get low impedance and high power output from one amp, or you can connect them in series to get 4 times that impedans and that much better damp factor. (better bass definition)

Or you can use a stereo amplifier as suggested.

scott_fx · 09-12-2006, 01:15 PM

in theory you could, but in application you'd probably end up ruining your sub. it's much safer to give the voice coils the exact same signal...only way you can do this is by letting them share. what happens if one component on the amp is weaker then on the other amp? you'll get a difference in the signals that are going to each voice coil and eventually kill the sub

Shadow · 09-12-2006, 02:08 PM

You can do this but you need a very expensive piece of equipment that makes sure the phase of the signals are completely aligned. This makes your idea cost SIGNIFICANTLY more than a more powerful amp.

scott_fx · 09-12-2006, 03:06 PM

curious...what is this piece of hardware?

Rob Withey · 09-12-2006, 04:29 PM

Why not just bridge the amps and connect voice coils in parallel or series?

mbkowns · 09-12-2006, 05:08 PM

Quote: Originally Posted by frugmonkey

it might be a stupid question, but if you use a dual voice coil sub is it possible to connect two identical amps, one to each coil, and have them both set up exactly the same?

has it been done before, or is it just a silly idea?

Shadow · 09-12-2006, 09:16 PM

Quote:

Why not just bridge the amps and connect voice coils in parallel or series?

That's called strapping. Not all amps can do that.

Scott, I forget what it's called but Alma had to have one on her Bronco when she was still with Stillwater.

bes51659 · 09-13-2006, 02:59 AM

I agree that in theory you might damage the speaker in one of two ways. If you have exactly the same signal out of phase the cone would not move at all and you would

a) get greater heat dissapation because of loss of emk. (The coil moving in the magnetic field will produce a contradirectional voltage that reduce current)
b) mechanical stress to the coil.

In real life the bass in stereo music is identical in left and right.

In real life the delay or phase is not difficult to maintain in low freq range. You do not need a very high quality amp as long as the impedance is not too low.

But my answer to your question is that I've never run a system like that for a long period of time.... Sorry :-)

But my question is the same as Rob's; Why? My guess is that you have an amp that can drive one coil but not the two in parallell and you are reluctant to connect them in series and loose some power. If so, don't buy a second identical amp. Buy a new one, adapted for the impedance of the two coils in series. That's my recommendation anyway.

In my book the only reason for dual coil is to be able to configure your speaker to get a well adapted load to your amp with 1,2 or 4 speakers.

And my 10 cents are; forget about 1ohm to get every watt out of your amp even if it is specified to deliver at that load. Every negative effect of your transmission will increase. Cables, internal impedance of your system... In short you will get a less defined bass. And even if the power is doubled you can only just notice that increase in a switch on - switch off blind test. (Thats also the reason you should never buy a dual speaker box for twice the money and twice the size) Buy a speaker with lots of dB's /W instead.

Rob Withey · 09-13-2006, 03:51 AM

Quote: Originally Posted by Shadow

That's called strapping. Not all amps can do that.

Ok, so the specific amps in discussion can't do that? That's a good reason.

Shadow · 09-13-2006, 08:37 AM

Scott, I found out what Alma had. They're called phase shifters and they were custom made 50 channel phase alignment processors. I don't know who made them but I can guarantee they weren't cheap especially considering that truck had over 4 miles of Kimber Select cable in it

frugmonkey · 09-14-2006, 01:04 PM

just looking at all the options really, i'm not quite sure which way to go with getting amps to power my subs, i can go for either two amps that will drive at one ohm and have them running one per sub. or a single one that will run the pair at two ohms
not been having much luck with my current sub amp, its been repaired by the manufacturer three times and hasnt really worked for more than an hour, and then every time you send it back it takes them FOUR MONTHS to not fix it properly!

so can anyone recommend a good amp (or amps) that will run either 1200-2500 RMS at one ohm, or a single that will do 2400ish to 5000 RMS at two ohms?
ive heard good things about the hifonics colossus, but they are very hard to come by in england, as it would seem most stuff like that is.
about the best option ive seen so far over here is the new model Directed 2400D, thats 1200rms at one ohm, but i'm not sure from past experience whether to use their stuff again, and they look a bit on the kids toys side of things, what with all the glowy lighty up bits, i hate flashy lights on stuff like that!

bes51659 · 09-14-2006, 02:17 PM

Oops, we are talking real power here... I guess you must be knowing what you are doing but anyway:

Whatever way you turn, your speaker can handle 2000W RMS. You only got the choice of 2x1000W in 2ohm or 1x2000W in 1 or 4 ohms.

The hifonics can drive 1x2000W in 4 ohm which directly translates to 2x1000w in 2 ohm. (bridge coupling) (I get suspicious when they spec 2x1100W..). All RMS if you beleive their spec. When you are using a bridge I would prefer the coils in serial rather than separate, but the difference is neglectable.

Forget about the coils in parallell to get one ohm, even if you can get a cheaper amp that states 2000W in 1 ohm. For reasons already mentioned which are even more valid with a Class D amp with passive filters at output.

Sorry no experience in amps in that segment :-) I have a DLS A5 myself.

Good luck.

Shadow · 09-14-2006, 03:23 PM

Memphis 4KW AKA Mojo will do 400WRMS

Quote:

When you are using a bridge I would prefer the coils in serial rather than separate, but the difference is neglectable.

Wrong, the wiring definitely makes a difference. Also, if he's wiring in parallel to get 1 ohm then series would give him 4 ohms. It's going to be TONS easier to get that power at 1 ohm than 4 ohms.

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