Running a sub without high pass???

[rsmithdrift]

This is a very technical amp setup question, so here are specs on the current setup:

I have a 1200w Sony amp. The amp is only 2ch. turned to half power, bass boost +10db, set to a frequency of 80hz. LPF is off.

I have a pair of 400w pioneer 6x9's in boxes attached to a 12" box with a 800w pioneer sub in it. and a 50wx4 Pioneer head unit.

I have the 6x9's on one channel each and the 12 bridged between the same (only) two channels. (so in theory it's getting twice the power as the 6x9's)

My question is, is it safe to run the 12" sub with the low pass frequency turned off? Will this terminally damage the sub or is it ok since the frequency is set to 80hz??

Also, how much power is actually going to each of the speakers?? My theory is the amp is set to 600w, 300w to each 6x9, 600w to the 12. Or is it all half because of the bridge? or does the bridge mean all are getting 600w? Or is it actually working as I expected?

[the converted]

Well it really depends on the sony amp. It's been a while since I've even had a thought about running something mixed mono. I'd guess that your getting around 150w to each 6x9 and 300w to the sub. There also used to be companies that sold high pass and low pass filter set ups for running mixed mono but I honestly haven't seen one in about 10 years.

[rsmithdrift]

Yeah, that makes sense, but my only real question was will the 12" blow from playing mids and highs due to the lack of a LPF???

If so then I either have to get a 4ch amp or run the 6x9's as bass only which would suck.

[the converted]

Nope, not going to sound great but it won't blow up.

[Looneybomber]

This is a very technical amp setup question, so here are specs on the current setup:

I have a 1200w Sony amp. The amp is only 2ch. turned to half power, bass boost +10db, set to a frequency of 80hz. LPF is off.

I have a pair of 400w pioneer 6x9's in boxes attached to a 12" box with a 800w pioneer sub in it. and a 50wx4 Pioneer head unit.

I have the 6x9's on one channel each and the 12 bridged between the same (only) two channels. (so in theory it's getting twice the power as the 6x9's)

My question is, is it safe to run the 12" sub with the low pass frequency turned off? Will this terminally damage the sub or is it ok since the frequency is set to 80hz??

Also, how much power is actually going to each of the speakers?? My theory is the amp is set to 600w, 300w to each 6x9, 600w to the 12. Or is it all half because of the bridge? or does the bridge mean all are getting 600w? Or is it actually working as I expected?

Wow, so let me get this strait...-You have a two channel amp with 10db of bass boost.-You have a pair of 6x9's hooked up to each channel of that amp.-You have a sub (single or dual VC?) bi-amped, not bridged, to that same amp?-Your first concern is the sub?

First off, an amp can't operate in bridged mode (two channels summed together as one) and also stereo mode. Draw a schematic of your wiring and I can show you how your speaker is bi-amped and not driven by a single bridged channel.

Second, bi-amping a single VC speaker, as in two amp channels going to a single VC, causes issues and unless the amp has good enough fail safe's, it could cause terminal problems. I did that same thing and would just get the amp shutting down on me, but it kept working. It has to do with the power coming out of the right channel, grounding back to the left channel or visa versa.

Third, HIGH PASS YOUR 6x9's!!!! You're sending a full range signal, plus 10db of bass to a speaker which, because you have a sub, should not be playing any bass. You run the risk of blowing those speakers.

The good news. Your sub is the safest piece of equipment you have...well besides your headunit, which should be used to power the 6x9's and allow you to low-pass your subwoofer.

As for power, you can figure that out by using the impedence of each speaker, ohm's law, and how much power that amp will produce at a given resistance.

[the converted]

First off, an amp can't operate in bridged mode (two channels summed together as one) and also stereo mode. Draw a schematic of your wiring and I can show you how your speaker is bi-amped and not driven by a single bridged channel.

Actually you can. I haven't seen anyone actually do it in over 10 years, but you can.

[rsmithdrift]

Uh, looney, you can bridge an amp. It's made for it, it even tells you how on the front of the amp. lol.

And on the speaker terminals on the amp it has "BTL (bridge)" with a line drawn showing you which two terminals to connect to make the bridge. The two channels have right/left with + and - for each channel and then a "bridge" with the line drawn from the left + to the right -

As for wether that is making the 6x9's act as bridged or not IDK. But my theory is that the power is going out from the amp TO the speakers so it is still behaving properly as two channels and a bridged channel.

And I have 5x7's in the factory speaker holes attached to the head unit.

And the 6x9's are 4-way speakers so I'm not worried about them getting the wrong frequency. They are made to handle 20hz to 20,000hz safely up to 400w.

I'm worried about the woofer because I blew one up because I had the frequency set to 200hz and it burnt out the voice coil eventually, so I'm afraid not using LPF will burn out the new one.

[the converted]

I not the debate at the moment. He is saying you can't run it in stereo and bridged at the same time.

[Looneybomber]

Actually you can. I haven't seen anyone actually do it in over 10 years, but you can.

Maybe we're thinking of something different, or they did some something different back in the day, but a true "bridge" of channels, sums two stereo channels into one mono channel.

As you can see in this picture (Yes it's a pro-amp because it's so much easier to see the gains on pro-amps vs car amps) only one gain is used, the other is at 0 (actually negative infinity), yet both channels show the same amount of output.



Thus, if properly bridged mono, it can't also simultaneously play stereo.

And the 6x9's are 4-way speakers so I'm not worried about them getting the wrong frequency. They are made to handle 20hz to 20,000hz safely up to 400w.

While they may claim to be rated for 400w and they're full range speakers, it doesn't mean you can flood them with 400w at any frequency from 20-20khz. *more on this later*

I'm worried about the woofer because I blew one up because I had the frequency set to 200hz and it burnt out the voice coil eventually, so I'm afraid not using LPF will burn out the new one.

Ok, your woofer will, by far, handle more power than your 6x9's. But anyway, since you don't think I know how to bridge an amp, I will think that you dont know how a speaker blows.

How speakers blow: Thermal failure or Mechanical failure.

Mechanical failure means the speaker's excursion reached beyond it's linear limits and one of many things happend, including, but not exclusively, a spider tearing, a spider or surround coming unglued, a voice coil former becoming damaged from bottoming, a VC former coming unglued from the cone, a cone destructing/bending.

Thermal failure, which is typically how companies rate the power handlings of their speakers, which may be higher than it's mechanical failure depending on enclosure and frequency played. It's a means of over heating a voice coil to the point it melts, burns, unwinds due to glue failure, or even burnt tinsel leads. On rare occasions, high heat over time will begin to demagnetize the speaker, reducing it's BL (look it up), causing it to perform at sub par levels, but I've yet to actually hear of that happening to anyone.

Why your 6x9's won't handle 400w. Mechanically, they're excursion limited in the bass region, which means they can thermally handle more power than what will damage them mechanically. If you start playing some bass heavy music they're forced to do the job that your subwoofer is already except they're not made for that, will wear out faster and run a higher risk of blowing. I would also bet, thermally, they can't handle 400w (pink noise, minimal crest) for more than a second.

At the same power level, for each octave you drop, excursion increases by 4x. If you want to see what that looks like, here's two of my 15's (in my house) dropping down, while my amp is still putting out the same amount of power.http://www.youtube.com/watch?v=gz3s4jKqtTw

So let's say those 6x9's have an xmax of 6mm, which would be a bit generous. If at 150hz, you're mechanically limited to 150w, then at 75hz, you would be mechanically limited to 37.5w. If you still gave it it the 150w, you will pop that speaker.

For that example, I am just throwing out a starting point number (150hz and 150w), I'm also ignoring any BL (look it up) reductions due to increased excursion and Cms (look that up too) increases, again, due to increased excursion. I may not be a transducer engineer, but I've talked with a few and learned a little bit.

[rsmithdrift]

So in other words all three speakers are getting the same amount of power. Same bass, same highs, same everything, all mono.... Makes sense.

But I'm not worried about my 6x9's blowing because I can go to level 50 before they start warping at all and I normally never go above 40 and usually it's at 30. Meaning 600w/3 = 200w each at half power = 100w is what they normally play at. They sound great and aren't even close to overexcursion untill level 50 where I'd say I'm hitting 175w.

I'm going to try to trade for a 4ch 600w amp. That way I can run the 6x9's stereo and otherwise the way they are now, and I can run the sub bridged across the other two channels on LPF so it'll sound 100%.

But untill then I don't think I have to worry about anything blowing, I'm just not getting the most out of my sub.