Turning 8 ohm drivers into 16 ohm

tobiasaurusrex · #1 04-14-2011, 05:47 AM

Hello,

I have a 4x12 ported bass cabinet, and I have to change out the speakers. I want to keep this cabinet: it's the size of a 4x10, but pushes more air and is warmer; It's as firm in the low end as an 18, but not muddy, foggy, and slow. It pushes all the mids to be present anywhere, and it can handle the 1,000 watts of the never-sweating headroom of my amp. The 4x12 configuration is also accommodatingly neutral through a 7-string's range.

To end up with a 4 ohm cabinet, which my head is designed to go into, I must use either 4 ohm (pairing then mixing series and parallel wiring) or 16 ohm drivers (with all parallel wiring). There seem to be no 4 or 16 ohm drivers available. There are listings for the Eminence Delta 12LFA as, "also available in 16 ohm," but they don't actually exist anywhere. (RMS rating must be 300 watts or higher.)

There is a good choice of 8 ohm 12" drivers... if I want a 2 ohm cabinet and run too much power (my amp can run this low, near short circuit load), or an 8 ohm cabinet and lose a lot of power.

So, I found some 8 ohm resistors that can handle 300 watts each. My idea is to gather some readily available 8 ohm speakers, wire a resistor to the negative lead of each, making the speakers 16 ohm, and wiring all four in parallel, which should deliver a 4 ohm, 1,200 watt cabinet (with 300 watt or up speakers, limited now by the resistors).

Is there a hole in this logic?

MuzikMan · #2 04-14-2011, 05:55 AM

Yes, there is a hole. All of the added power would be spent heating up the resisitors, with no gain to the speakers. In fact, you would probably slightly reduce the signal to the speakers.

Why do you need to replace the speakers?

christw · #3 04-14-2011, 06:07 AM

Why replace what's already good? More power through your cab will make a negligible difference. What you really want if you need to be louder is another cab!

Eric Moesle · #4 04-14-2011, 06:13 AM

Half of your total power will be expended just to heat the resistors, and half to your speakers. That will result in a net LOSS of power to your speakers.

Also, keep in mind that the minute you change to different drivers in your cabinet, the cabinet will sound different. If you are happy with the sound now, leave it alone.

I don't think you understand that the difference in power going from 8 ohms to 4 with the same speaker area results in a negligible increase in volume, barely perceptible. Don't get yourself caught up in the numbers.

billfitzmaurice · #5 04-14-2011, 06:20 AM

Quote:

Originally Posted by tobiasaurusrex

Is there a hole in this logic?

What you propose is the same as dragging a 2,000 pound anchor behind your car so that you can 'get all the horsepower out of my engine'. Forget the watts, they just don't matter.

tobiasaurusrex · #6 04-14-2011, 06:26 AM

So, with Nikola Tesla's alternating current running, I'll drive the speaker on one cycle, then heat the resistor with the other cycle, but I'd be better off running the speaker on both cycles with the diminished wattage output of double resistance from 4 to 8 ohms.

Ok, thanks.

tobiasaurusrex · #7 04-14-2011, 06:33 AM

(I'm not trying to change anything, I'm trying to keep it the same, but I can't just replace old, tired drivers with a like item that isn't made anymore.)

parsons · #8 04-14-2011, 06:35 AM

300W, 16ohm Eminence Deltas. Took me a whole 30 seconds to find on google. $64 shipped to your door, each.
EMINENCE 12" American Standard Series Speakers - 16ohms in Musical Instrument Speaker Monitors at JR.com

Downunderwonder · #9 04-14-2011, 06:36 AM

Well done, you got a rise out of BFM.

tobiasaurusrex · #10 04-14-2011, 06:41 AM

Quote:

Originally Posted by parsons

300W, 16ohm Eminence Deltas. Took me a whole 30 seconds to find on google. $64 shipped to your door, each.
EMINENCE 12" American Standard Series Speakers - 16ohms in Musical Instrument Speaker Monitors at JR.com

Well, that's a new listing, and as you can see, they don't actually have them. They've just been told of a probable date of shipment. I found that page before and it just said out of stock, date unknown.

billfitzmaurice · #11 04-14-2011, 06:44 AM

Quote:

Originally Posted by parsons

300W, 16ohm Eminence Deltas. Took me a whole 30 seconds to find on google. $64 shipped to your door, each.
EMINENCE 12" American Standard Series Speakers - 16ohms in Musical Instrument Speaker Monitors at JR.com

The Delta12B has only 2.4mm xmax, making it unsuitable for electric bass. 3mm is the absolute minimum acceptable, while 4mm is the average value. One cannot consider driver size, impedance and watts alone.

tobiasaurusrex · #12 04-14-2011, 06:46 AM

Quote:

Originally Posted by parsons

300W, 16ohm Eminence Deltas. Took me a whole 30 seconds to find on google. $64 shipped to your door, each.
EMINENCE 12" American Standard Series Speakers - 16ohms in Musical Instrument Speaker Monitors at JR.com

Yeah, with a base frequency of 65 Hz, and not even the 44 or 48 Hz of most, my low-B will think I don't love it anymore. No thanks. I'll go with 8 ohms that start lower. After all, if I do want the power, I can actually wire them to 2 ohms easily. I've just been riding with 4, and didn't want to change it.

Never_grew_up · #13 04-14-2011, 06:57 AM

Why not just use 4 ohm drivers? Combining series & parallel wiring you can still end up w/a 4 ohm cabinet.

Robby Hoinsky · #14 04-14-2011, 07:38 AM

Shoving the first acceptable 16 ohm woofer from the limited available selection that's out there into a cabinet not designed for them in the hopes to gain a theoretical 3dB increase in maximum output to replace speakers that you LOVE the sound of seems like at best a lateral move and at worst the destruction of mankind. I would rethink this plan.

Robby

Electricblue · #15 04-14-2011, 07:42 AM

Quote:

Originally Posted by billfitzmaurice

What you propose is the same as dragging a 2,000 pound anchor behind your car so that you can 'get all the horsepower out of my engine'. Forget the watts, they just don't matter.

That is possibly the best quote i've ever heard.

4Mal · #16 04-14-2011, 07:57 AM

recone the old tired drivers

mmbongo · #17 04-14-2011, 09:02 AM

Quote:

Originally Posted by tobiasaurusrex

Yeah, with a base frequency of 65 Hz, and not even the 44 or 48 Hz of most, my low-B will think I don't love it anymore. No thanks. I'll go with 8 ohms that start lower. After all, if I do want the power, I can actually wire them to 2 ohms easily. I've just been riding with 4, and didn't want to change it.

What are the ones you have in the cabinet now? You might be surprised

tobiasaurusrex · #18 04-14-2011, 09:10 AM

Finally found some Faitals that match frequency specs pretty well to present, are readily avialable in 4 ohm, have an Xmax of 4.9, and them new neodymium magnets - to shed about 36 pounds(!) off the thing, to boot.

I've never used Faitals, how much hate and rage do you all have for them?

MuzikMan · #19 04-14-2011, 09:12 AM

Faital is a good quality brand IMO. All that is left to do now is model the chosen driver into your cab to see if your cab is a good match for the drivers.

Selta · #20 04-14-2011, 09:13 AM

You really need to make sure that they're going to work well in the box you intend to put them in. Just because the have an OK X-Max, match the impedance you want and have supposed "frequency" spec listed, doesn't mean the other 17 or so specs you need to worry about

.
You can't just drop any driver in any cab and have great tone. You might get lucky and buy the right driver, but your chances are slim.
Also, all of this work for some extra wattage that you won't even notice anything from? Why bother? You're not going to notice any extra volume from doing this - you know that, right?
Also, you're dropping unknown speakers into the cab that you supposedly love the tone of. Why? You're going to change that tone.