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Peavey subcompact 15 subwoofer - Any good?


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There is a pair of these available locally, unloaded. quite cheap.

I figure with new drivers to have less than $210 in each one.

Worth it? manual says sensitivity 98db / max 118db.

http://dl.owneriq.net/c/c365ff71-12c8-46dc-815f-00a2b01b0d50.pdf

worth tinkering with?

 

I have a tiny, occasionally used PA, looking to upgrade so that I do not use my bass cabinet for sub duty. Once in a great while do ipod music or vocals for live band.

 

thanks

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The 98db spec is in free air. Coupled to the ground you should see 3 to 6 db's more. Put the 2 of them coupled together and you'll get some more bass in the 50 to 150 hz range. Of course it would be better to use the factory speakers for this box. Get hold of peavey first to see if they are still available or they have a recommended replacement. I've owned and used Subcompact 18's for years and they give a good thump for what they are. If you have a spare amp/crossover and just need some more thump/bass then its up to you. I know the box construction is good for the years they were manufactured.

 

https://assets.peavey.com/literature/manuals/80301952.pdf

 

https://peavey.com/support/spkrcomponents/spkr_comps.pdf

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I had a pair of the Subcompact 18 subs, as well. Two things to remember; It's a band pass design which means that any content above or below it's designed output disappears quickly and sometimes not so nicely, so you will still need a crossover and tops that cover as low as the sub requires. It does not play well with other sub woofer designs. Early on, out of necessity, I used these with some front loaded subs. Between polarity issues, bad EQ habits and the two different designs, my low end was pretty chopped up with cancellations in some areas and combining in others. But using them by themselves with a decent top they do what they're supposed to do. Not what I'd call musical or accurate, if you're not currently using subs it's a good first step down that road and will add a new dimension to your sound.

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Max sound pressure level 118db. Not much output for a sub for rock bands.

 

That is in free air. Add 6db's for on the floor and another 6 if they are placed side by side for 130db's total for the 2. You can see on the link I put up the dotted line is the box on the floor. Not supper loud but it seems the OP is looking just for a little more and a light box.

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I'm going to disagree with the boundary and speaker to speaker coupling numbers here... while theoretically there may be 6dB of gain due to 1/2-space loading, in practice this is rarely achieved. IMO, 4dB is about as good as cab be expected (and interference issues may become a problem due to higher frequency reflections form the boundary.

 

On the coupling between speakers, my measurements bear out 3dB (theoretical) from the displacement coupling, the additional 3dB is due to the doubling of power when 2 drivers are parallel connected to an amplifier that behaves as a voltage source and the power doubles. Even these 3dB contributions are rarely 3dB in practice.

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I'm going to disagree with the boundary and speaker to speaker coupling numbers here... while theoretically there may be 6dB of gain due to 1/2-space loading, in practice this is rarely achieved. IMO, 4dB is about as good as cab be expected (and interference issues may become a problem due to higher frequency reflections form the boundary.

 

On the coupling between speakers, my measurements bear out 3dB (theoretical) from the displacement coupling, the additional 3dB is due to the doubling of power when 2 drivers are parallel connected to an amplifier that behaves as a voltage source and the power doubles. Even these 3dB contributions are rarely 3dB in practice.

 

Thanks harmony. Lost a large post. I'll redo it in the morning.... Sigh

 

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I'm going to disagree with the boundary and speaker to speaker coupling numbers here... while theoretically there may be 6dB of gain due to 1/2-space loading, in practice this is rarely achieved. IMO, 4dB is about as good as cab be expected (and interference issues may become a problem due to higher frequency reflections form the boundary.

 

On the coupling between speakers, my measurements bear out 3dB (theoretical) from the displacement coupling, the additional 3dB is due to the doubling of power when 2 drivers are parallel connected to an amplifier that behaves as a voltage source and the power doubles. Even these 3dB contributions are rarely 3dB in practice.

 

Short version. When a person mentioned the low output of the sub I noted the sub is measured in free air. Boundary loading does give a measured 6 DB increase in spl. Most other manufacturer's use boundary loading to give their speakers this "free". SPL increase. Peavey's own spec sheet shows this in the graph. It's an industry standard.

As you know when you double the surface area you gain 3dbs and double the wattage you get another 3dbs. When subs are properly coupled I've measured this with SMAART more times than I can remember and always get this. A sub may have reduced output do to room issues and have a 3db reduction in average room output. Adding another sub properly coupled and powered gives you 6 DBS more average spl from that point.

 

Yes if you hang the second sub on the same amp channel you won't get the full spl increase but that's the operators choice and doesn't change the math. ( well maybe with a class A amp that could double wattage in a perfect world ;-) ) What "could" happen if not done right doesn't make the math wrong. It does hold up.

 

A car may be rated at 30 mpg. Drive it up hills and too fast and you'll see less. Real world is 30 mpg measured. It is a fact. What you do to it from there doesn't change this.

 

Have a great rest of the weekend. Wish my longer post had made it. HC is fading away..... :-(

 

Doug

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Short version. When a person mentioned the low output of the sub I noted the sub is measured in free air. Boundary loading does give a measured 6 DB increase in spl. Most other manufacturer's use boundary loading to give their speakers this "free". SPL increase. Peavey's own spec sheet shows this in the graph. It's an industry standard.

As you know when you double the surface area you gain 3dbs and double the wattage you get another 3dbs. When subs are properly coupled I've measured this with SMAART more times than I can remember and always get this. A sub may have reduced output do to room issues and have a 3db reduction in average room output. Adding another sub properly coupled and powered gives you 6 DBS more average spl from that point.

 

Yes if you hang the second sub on the same amp channel you won't get the full spl increase but that's the operators choice and doesn't change the math. ( well maybe with a class A amp that could double wattage in a perfect world ;-) ) What "could" happen if not done right doesn't make the math wrong. It does hold up.

 

A car may be rated at 30 mpg. Drive it up hills and too fast and you'll see less. Real world is 30 mpg measured. It is a fact. What you do to it from there doesn't change this.

 

Have a great rest of the weekend. Wish my longer post had made it. HC is fading away..... :-(

 

Doug

 

The math works but Andy is saying that additional factors need to be in that math, and that the reality at our ears is usually not what the math implied.

 

I do agree that the site ain't what is was....

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Just like the estimated MPG, this is based on a lot of theoretical assumptions that simply do not accurately represent the real world (often by a pretty wide margin).

 

If you were to add the theoretical +6dB to the free air 98 dB, you would have a "sub-compact" bandpass sub capable of 104dB/1W/1M. I know quite a few designers who would sell their mothers for those numbers. In practice, I would expect somewhere nearer 100-101dB/1W/1M, and some of this comes at the expense of maximum SPL (limited by power handling)

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Just like the estimated MPG, this is based on a lot of theoretical assumptions that simply do not accurately represent the real world (often by a pretty wide margin).

 

If you were to add the theoretical +6dB to the free air 98 dB, you would have a "sub-compact" bandpass sub capable of 104dB/1W/1M. I know quite a few designers who would sell their mothers for those numbers. In practice, I would expect somewhere nearer 100-101dB/1W/1M, and some of this comes at the expense of maximum SPL (limited by power handling)

 

Well yes and no. The 98 Db's with 6 more for a boundry should hold true if the peavey's spec is correct. The real number to note is the 118 DB Max (Max) with a 6 DB increase to a not so loud 124 dbs Max. Max would be 6 Db's above rms. The 6 DB add for boundry additional gain is pure science. The other factors that may or may not effect this does not change this. Those are Peavey spec's. Maybe you should contact them. Again a 6db gain going from free air to a boundry load is pure science. You could get this if done correctly. You may get less but NOT always so to generalize would be miss information. A different placement or incorrect placement may take away from this but the number none the less is correct. You really love to beat a dead horse don't you ;-) as in such a old thread. 1+1=2 if someone does this wrong and gets a different answer it doesn't change the fact that the math is correct. At least we're keeping some threads going here. It has slowed down so much from 10 years ago.

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Just like the estimated MPG, this is based on a lot of theoretical assumptions that simply do not accurately represent the real world (often by a pretty wide margin).

 

If you were to add the theoretical +6dB to the free air 98 dB, you would have a "sub-compact" bandpass sub capable of 104dB/1W/1M. I know quite a few designers who would sell their mothers for those numbers. In practice, I would expect somewhere nearer 100-101dB/1W/1M, and some of this comes at the expense of maximum SPL (limited by power handling)

 

I also wanted to add if you look at the room response of the box in the link above, improperly labeled as impedance 1 that there is a 6db gain for the in room response. But there is only a peak at around 80 hz that goes to 104dbs . The overall response in room is closer to 101. So common sense says that the box 1w1m spl would be closer to 95 Db's. Is Peavey fugging the specss? ;-) Still this doesn't change a 6 DB gain for boundry loading. I bet that even in just about an room measured at 1meter this holds true.

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