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Author Topic: Modify Peavey SP4's?  (Read 20326 times)

David A. Parker

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Re: Modify Peavey SP4's?
« Reply #20 on: February 11, 2011, 07:50:34 PM »

Ivan Beaver wrote on Fri, 11 February 2011 18:40

David A. Parker wrote on Fri, 11 February 2011 09:01



It is very possible to get the subs to play well with the tops-even overlaping freq.

If done properly, you will get good summation.

Yes if you just "throw they up" and pour on the juice you can likely tear them up because they are not working together well.

But with careful alignment you can get some good results.


The careful alignment part would put that setup out of the reach of many. As others have said, the OP would probably be better off leaving the internal crossovers in his cabs alone. Big name cabs have that sort of thing programmed into the magic box that comes with them. A friend had a KV system. It had some serious "black box" alignment and such going on. It had front loaded and folded horn and bandpass subs working together, extremely well. I'm sure they didn't get that one right the first time!
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David Parker
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Jay Barracato

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Re: Modify Peavey SP4's?
« Reply #21 on: February 13, 2011, 08:26:19 AM »

I am not sure why anyone would think putting a sub with a box with 2 15's is any different than putting a sub with a box with 115.
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Jay Barracato
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David A. Parker

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Re: Modify Peavey SP4's?
« Reply #22 on: February 13, 2011, 08:53:53 AM »

Jay Barracato wrote on Sun, 13 February 2011 07:26

I am not sure why anyone would think putting a sub with a box with 2 15's is any different than putting a sub with a box with 115.

because a lot of 2-15 cabs have the bottom 15 lo-passed passively internally such that when you hi-pass the cab with your active crossover, it pretty much cuts the bottom 15 out, negating it's value.
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David Parker
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Mac Kerr

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Re: Modify Peavey SP4's?
« Reply #23 on: February 13, 2011, 11:39:56 AM »

David A. Parker wrote on Sun, 13 February 2011 08:53

Jay Barracato wrote on Sun, 13 February 2011 07:26

I am not sure why anyone would think putting a sub with a box with 2 15's is any different than putting a sub with a box with 115.

because a lot of 2-15 cabs have the bottom 15 lo-passed passively internally such that when you hi-pass the cab with your active crossover, it pretty much cuts the bottom 15 out, negating it's value.


Maybe you could provide a link to those "lots" of speakers that roll off the bottom 15 below the 100Hz or so where you would put your HPF on the full range speakers you are using with subs. Even if the bottom 15 starts to roll off at 200Hz you still get a full octave of low frequency reinforcement from it. In the OP's case where the bottom 15rolls off above 900Hz he would still get all the lows and low mids out of both 15s.

Mac
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David A. Parker

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Re: Modify Peavey SP4's?
« Reply #24 on: February 13, 2011, 04:25:02 PM »

Mac Kerr wrote on Sun, 13 February 2011 10:39

David A. Parker wrote on Sun, 13 February 2011 08:53

Jay Barracato wrote on Sun, 13 February 2011 07:26

I am not sure why anyone would think putting a sub with a box with 2 15's is any different than putting a sub with a box with 115.

because a lot of 2-15 cabs have the bottom 15 lo-passed passively internally such that when you hi-pass the cab with your active crossover, it pretty much cuts the bottom 15 out, negating it's value.


Maybe you could provide a link to those "lots" of speakers that roll off the bottom 15 below the 100Hz or so where you would put your HPF on the full range speakers you are using with subs. Even if the bottom 15 starts to roll off at 200Hz you still get a full octave of low frequency reinforcement from it. In the OP's case where the bottom 15rolls off above 900Hz he would still get all the lows and low mids out of both 15s.

Mac


I never said they rolled them off below 100hz, but some roll them off at 400hz, and when you hi pass at 100hz, I stand by what I said, the bottom 15 isn't doing much. Obviously, the 2-15 cabs we are referring to were not designed to be used with subs, although they work well with subs anyway. One benefit is that if you stack a 2-15 cab on a sub, it gets the horn up closer to where it needs to be. My main rig for many years was 2-15 cabs on top of 2-18 cabs. A lot of work to stack, but it worked very well. Not saying that was the best design, but it did work well.
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David Parker
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Mac Kerr

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Re: Modify Peavey SP4's?
« Reply #25 on: February 13, 2011, 05:00:43 PM »

David A. Parker wrote on Sun, 13 February 2011 16:25

Mac Kerr wrote on Sun, 13 February 2011 10:39

David A. Parker wrote on Sun, 13 February 2011 08:53

Jay Barracato wrote on Sun, 13 February 2011 07:26

I am not sure why anyone would think putting a sub with a box with 2 15's is any different than putting a sub with a box with 115.

because a lot of 2-15 cabs have the bottom 15 lo-passed passively internally such that when you hi-pass the cab with your active crossover, it pretty much cuts the bottom 15 out, negating it's value.


Maybe you could provide a link to those "lots" of speakers that roll off the bottom 15 below the 100Hz or so where you would put your HPF on the full range speakers you are using with subs. Even if the bottom 15 starts to roll off at 200Hz you still get a full octave of low frequency reinforcement from it. In the OP's case where the bottom 15rolls off above 900Hz he would still get all the lows and low mids out of both 15s.

Mac

I never said they rolled them off below 100hz, but some roll them off at 400hz, and when you hi pass at 100hz, I stand by what I said, the bottom 15 isn't doing much. Obviously, the 2-15 cabs we are referring to were not designed to be used with subs, although they work well with subs anyway. One benefit is that if you stack a 2-15 cab on a sub, it gets the horn up closer to where it needs to be. My main rig for many years was 2-15 cabs on top of 2-18 cabs. A lot of work to stack, but it worked very well. Not saying that was the best design, but it did work well.



If they roll off at 400Hz the bottom 15 is covering 2 full octaves of the low end if they are high passed at 100Hz. That is probably more than most subs will be covering. A common sub with a low frequency limit of around 30, which is pretty good for most subs, would have to be low passed at 120 Hz to cover 2 full octaves. The extra 15 will be providing additional output in the low mid range that so many people seem to think they don't have enough of. If you move the crossover frequency to 80Hz the bottom 15 will cover more than 2 octaves, and the sub would have to have response to 20Hz (not that common) to cover 2 octaves.

I fail to see how you come to the conclusion that the speakers being discussed were not intended to be used with subs. Subs are not the low frequency section of a full range speaker, they are the extended response below (sub) the range of a full range speaker. I can not think of a single full range speaker that has been designed to not be used with a sub to extend the low frequency response. If you know of one, and have some data from the manufacturer to support your view, please share it.


Mac
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Jay Barracato

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Re: Modify Peavey SP4's?
« Reply #26 on: February 14, 2011, 07:53:13 PM »

Mac Kerr wrote on Sun, 13 February 2011 16:00

David A. Parker wrote on Sun, 13 February 2011 16:25

Mac Kerr wrote on Sun, 13 February 2011 10:39

David A. Parker wrote on Sun, 13 February 2011 08:53

Jay Barracato wrote on Sun, 13 February 2011 07:26

I am not sure why anyone would think putting a sub with a box with 2 15's is any different than putting a sub with a box with 115.

because a lot of 2-15 cabs have the bottom 15 lo-passed passively internally such that when you hi-pass the cab with your active crossover, it pretty much cuts the bottom 15 out, negating it's value.


Maybe you could provide a link to those "lots" of speakers that roll off the bottom 15 below the 100Hz or so where you would put your HPF on the full range speakers you are using with subs. Even if the bottom 15 starts to roll off at 200Hz you still get a full octave of low frequency reinforcement from it. In the OP's case where the bottom 15rolls off above 900Hz he would still get all the lows and low mids out of both 15s.

Mac

I never said they rolled them off below 100hz, but some roll them off at 400hz, and when you hi pass at 100hz, I stand by what I said, the bottom 15 isn't doing much. Obviously, the 2-15 cabs we are referring to were not designed to be used with subs, although they work well with subs anyway. One benefit is that if you stack a 2-15 cab on a sub, it gets the horn up closer to where it needs to be. My main rig for many years was 2-15 cabs on top of 2-18 cabs. A lot of work to stack, but it worked very well. Not saying that was the best design, but it did work well.



If they roll off at 400Hz the bottom 15 is covering 2 full octaves of the low end if they are high passed at 100Hz. That is probably more than most subs will be covering. A common sub with a low frequency limit of around 30, which is pretty good for most subs, would have to be low passed at 120 Hz to cover 2 full octaves. The extra 15 will be providing additional output in the low mid range that so many people seem to think they don't have enough of. If you move the crossover frequency to 80Hz the bottom 15 will cover more than 2 octaves, and the sub would have to have response to 20Hz (not that common) to cover 2 octaves.

I fail to see how you come to the conclusion that the speakers being discussed were not intended to be used with subs. Subs are not the low frequency section of a full range speaker, they are the extended response below (sub) the range of a full range speaker. I can not think of a single full range speaker that has been designed to not be used with a sub to extend the low frequency response. If you know of one, and have some data from the manufacturer to support your view, please share it.


Mac




Mac,

I am with you in this game. For the record, the Meyer MTS4 has the sub built into the box which lists a frequency range of 32 hz-18 khz. But it could also be combined with other sub boxes such as the PSW-4. Actually I think it is a shame that system has been discontinued.


But that in no way negates the argument. Take the double 15 and cross it over somewhere between 80 and 100, let the subs carry everything below that. Both 15's will still have plenty to do.
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Jay Barracato
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John Watson

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Re: Modify Peavey SP4's?
« Reply #27 on: February 15, 2011, 11:25:24 PM »

Thanks for all the info. I'm going to cross the subs @ 90hz to start and then try 80hz and see which sounds best.
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