BillFitzmaurice.info

I recently got a vehicle with a huge trunk, and would like to put my pair of T24s in there when I'm not using them for gigging. They each have a single 4-ohm BP102 driver.

The only (12v) amp I currently have is rated to output 80W x 2 channels @ 4-ohms, or 325W bridged at 4-ohms.

I know I should wire it all up and check with a multimeter how much voltage the amp can actually put out, but I can't get a hold of a wiring harness until tomorrow, so I'm going to ask some (probably) stupid questions anyway..

What bad can come of trying to run the amp at 2-ohms bridged? (the literature for the amp does NOT say the amp is stable at 2-ohms bridged, it is however in 2 channel mode)

What bad can come of running a 200W RMS rated speaker at <80W? I called Crutchfield just for the hell of it because I originally purchased the amp from them a few years ago, and the tech said I can blow the speakers by under powering them, and I was like

Or should I just run one T24 until I get a better amp?

If you could blow a speaker by under powering it, we would all be buying new speakers every low volume gig we did.

Running the amp at 2 ohms bridged is a bad idea. When you bridge an amp each side of the amp "sees" half the load. So two channels at 2 ohms = 4ohm load minimum bridged. If you ran it 2ohms bridged each side of the amplifier would be running a 1 ohm load. If you didnt turn it up past "1" you would probably be ok, but since you are asking about running at unsafe loads to maximize watts, I doubt that is your intention. The difference between 160 Watts (each channel at 80W) and the 325 watts in bridged mode is only a 3db gain and a whole lot more work on your amp. Try it with them run stereo and see if you need more before running equipment past its limits or buying something else.

My .02

Benj

Run one per channel. Don't play dubstep full volume. Without a highpass 80w is dangerous even if you had a limiter. Limit for t24 iirc is same as t39, 150 watts.

pond wrote:I called Crutchfield just for the hell of it because I originally purchased the amp from them a few years ago, and the tech said I can blow the speakers by under powering them

They be idiots.

I think the under-power = blown speakers myth started when some idiot tried to get 150 db using 50 watts to a sub and drove it to the point of clipping trying to achieve the volume. The speakers said rated for 500 watts and he was only using 50, so the myth started...

Clipping kills speakers, under-powering does not.

Jon Barnhardt wrote:
Clipping kills speakers, under-powering does not.

Clipping does not kill speakers.
http://billfitzmaurice.info/forum/viewt ... =10&t=1886

Bill Fitzmaurice wrote:

Jon Barnhardt wrote:
Clipping kills speakers, under-powering does not.

Clipping does not kill speakers.
http://billfitzmaurice.info/forum/viewt ... =10&t=1886

So then why are we supposed to keep it out of the red, if clipping does not hurt drivers? (taking for granted that available power is below driver rated power)

Jon Barnhardt wrote:

Bill Fitzmaurice wrote:

Jon Barnhardt wrote:
Clipping kills speakers, under-powering does not.

Clipping does not kill speakers.
http://billfitzmaurice.info/forum/viewt ... =10&t=1886

So then why are we supposed to keep it out of the red, if clipping does not hurt drivers? (taking for granted that available power is below driver rated power)

Clipping DOES create square waves, which sound like crap, even if there's not enough power there to burn anything.

However... it is true that there is more RMS power (area under the curve) of a square wave at a given voltage than a sine wave at the same voltage... hence a highly clipped signal potentially delivers more power than an unclipped one, which can put a driver over the top thermally at a lower relative volume (and voltage), and do so without causing overexcursion. Clipping alone is not inherently dangerous, but clipping which causes overpowering resulting in thermal failure... that's different. Of course, that falls under the category of the impossibility of correcting "stupid."

IMO it sounds like a$$!

Benj

Jon Barnhardt wrote:

Bill Fitzmaurice wrote:

Jon Barnhardt wrote:
Clipping kills speakers, under-powering does not.

Clipping does not kill speakers.
http://billfitzmaurice.info/forum/viewt ... =10&t=1886

So then why are we supposed to keep it out of the red, if clipping does not hurt drivers? (taking for granted that available power is below driver rated power)

Jon Barnhardt wrote:
So then why are we supposed to keep it out of the red, if clipping does not hurt drivers? (taking for granted that available power is below driver rated power)

Because it sounds bad. If clipping hurt drivers there would be no such thing as fuzz tones or synthesizers, and guitar players would all be members of the driver of the week club.

OP will be lucky to hear his mains clipping over the din of his car shaking to bits.

Gregory East wrote:OP will be lucky to hear his mains clipping over the din of his car shaking to bits.

Well, the thrilling conclusion is that my new amp came, (a Sound Ordnance M1350, $90) and it works swimmingly. Swapped out the head unit, and wired up the amp, and everything worked on the first try! (never had that happen before...) Still using the OEM door speakers (which are surprisingly decent), but I have the head's crossover set at 80Hz, so they fit the sound fine. The el-cheapo amp's knobs were confusing, but I seem to have them set appropriately (HP @ 40Hz, 'input voltage' which I guess means 'gain' on a normal amp? set at ~4v to match the head's pre-outs, and some other ones I forget). No 'bass boost' or anything on anywhere.

Hooked up my multimeter, and it was peaking at 25v with the volume cranked up to 32 out of 35 max to some really heavy dubstep. A match made in heaven? I think so Note- it was unbearable to sit in the cabin at this point, I was using the remote control and had the multimeter wires coming through the window.

At human listening levels, things sound incredible. A little bump up in the Mids EQ, and I couldn't be happier. Definitely made the 1500 miles I drove this weekend bearable.

Anyway on to the media!

http://www.facebook.com/v/567895677504

AWESOME! That's insane! Glad to see you're driving a Forester, I have a Fozzy as well. And I now know that 2 T24s will fit in a Forester....

But I have to disagree with you on the OEM speakers, at least for me they are awful. (2006 Forester 2.5 X 86k miles, no fancy trim or audio upgrades.)

Cool project.

That poor car!