Impedence help

[acex008]

For those XO geniuses...

So I've got a 2ohm SVC 12" Sub with these specs:

Qts : .375
Qes : 0.49
Qms : 1.506
Fs : 25 Hz
Re : 1.8
Vas : 157 L
MMS : 90g
BL : 7.2 Tm
SPL : 89.1 dB
SD : 510 M^2
Xmax : 9.1 MM

Since I can't find a cheap (under $120) amplifier that'll handle the 2ohm load, will the resistor in the link below get me to 4ohms or higher load to the amp? It's an Ohmite 2ohm 100W tunnel style power resistor which would essentially create an L-pad to attenuate the sub.

HERE

If not, what load would connecting that resistor in series to the sub give me for loading on the amp? Will I need other components to get me to the 4ohm (min.) loading? Also, will this reduce the output levels (dB) of the sub or the sound quality?

[---k---]

How about just getting a second on of those drivers and wire them in parallel to get 4 ohms?

I don't know about the resistor. I'm skeptical that it will do what you want. But, I'll let someone like Thomas answer that one.

[acex008]

I've been searching for one for over 2 months with no success. The resistor will be a temporary fix until I find another driver. I just had an idea. Would wiring ANY driver that is 2ohms in parallel get me to 4ohms? I just had an idea, I basically could buy the cheapest 2ohm speaker I can find and pull out the cone! LOL

For instance = HERE

[ThomasW]

1/2 the of the amp's power would go into the resistor. So not a good idea IMO.

[acex008]

i see, thanks thomas, how about the cheap 2ohm driver idea? Would I just need to connect to the VC and leave the magnet? If I pull the cone, that way I won't hear the extra driver...

[Quwiksilver]

How about just getting a second on of those drivers and wire them in parallel to get 4 ohms?

I don't know about the resistor. I'm skeptical that it will do what you want. But, I'll let someone like Thomas answer that one.

I think you meant in series, correct?

acex008, I don't see a fundamental problem with adding the resistor. That resistor can handle quite a bit of power. However, Thomas is right, there would be a lot of power being dissipated in it causing it to get pretty hot. Might be a pretty serious fire hazard, especially inside a box.

I second the second sub idea (eh?). How could you go wrong with more bass?

[Jonasz]

How about just getting a second on of those drivers and wire them in parallel to get 4 ohms?

You mean in serie, not parallell I guess?

[ThomasW]

That's the same as using a resistor, 1/2 the power would go to that driver.

The only reasonable options are

1) get an amp that will drive a 2 ohm load
2) get a second 2 ohm driver like the one you have now
3) sell the driver and get one more suitable to what you're doing.

[acex008]

bummer, thanx guys!

[bluewizard]

Let's look at this simply. If you put a resistor in series, then you can achieve any relative resistance you want, but all the signal across the resistor is lost signal to the speaker. In other words, you throwing away a lot of sound across that passive resistor.

How many of these woofers do you have, and can you get more? The best bet would be two of these speakers wired in series, each speaker would only get half the signal, but at least they would both be putting out sound. In a sense, you half the signal, but you double the cone area, so the net result is zero in terms of loudness; two speakers in series is just as loud as one speaker alone. But raw loudness isn't everything, there is still an advantage to this configuration.

TWO ohms speakers are likely intended to be Auto/Car woofer or subwoofers. Since cars can't generate very high voltages, they make up for it by delivering enormous amounts of current. To get more current for a given voltage, you use a lower impedance speaker. This is great in a car, but a disadvantage in a home stereo.

There are a few home stereos, very few, that are 2 ohms capable, but in a commercial amp, even some relatively low cost ones, 2 ohm capable is common.

The only working solution for home audio use, is to use more than one of them in a given speaker, and raise the impedance by ganging them together.

Hey...just one man's opinion.

Steve/bluewizard

[acex008]

i understand the implications. Thanks for all the feedback.

No, how about a XO design for a 5" midbass SVC 2ohm driver and a 12" SVC subwoofer SVC 2ohm driver with a cutoff freq. of 70Hz?

[---k---]

I think you meant in series, correct?

Yeah, guess so. I always get that backwards for some reason. Must be my dyslexia.



OP: Sell the driver! By the way, what is it?

[acex008]

elemental designs EHQS12

[Dennis H]

How big a box can you handle? The main effect of adding a resistor is to increase the Qes of the driver. You can extend the low end with a resistor and a big box at the cost of less efficiency up high. Four sealed boxes, all with 100 watts.

Yellow: 2.5 cu.ft.
Green: 2.5 cu.ft. with 2 ohm resistor
Cyan: 10 cu.ft.
Red: 10 cu.ft. with 2 ohm resistor

[pedroskova]

elemental designs EHQS12

Well, waddyaknow, 8O I've got 8 of these for my 3way active OB project. I'm still waffling over running them series/parallel for 2 ohms (I have a QSC PA amp that claims to be 2 ohm stable) or in series for 8 ohm. Their sensitivity isn't really a problem, since I have a lot of leeway in level matching via the gain structures of the amps I have on hand.

...couldn't pass 'em up at $13.00/driver...that really tickled my cheapbone. 8)

[acex008]

I couldn't pass it up for that price either, that's why I bought one, but I should have bought two... Hindsight is 20-20. I bought it originally to run in my car, but have since sold the car... Anyhow, I've just found another driver and it is being shipped out later today!!! So that solves my loading issues. I just purchased a Dayton SA240 to power them. 240W @ 4ohms. So each sub will see 120W. I'll be building seperate ported enclosures for each tuned to 24Hz. Should be much better than the 50W Yamaha 6.5in. powered sub I'm replacing them with!!! :-D