Setting up sub frequencies with 2 crossovers? AMP+Deck

[PollyCranopolis 10+ year member]

I have a Premier 880 PRS, running sub outs back to a Concept CD-2410. Neither the Concept amp, or the 880 PRS has the ability to totally disable the sub crossover. I'm wondering which way would be best to set them knowing this. My options include:

A: Setting the deck sub crossover to max (200), then setting the amp to 80hz or below so the Concept cuts the frequency down once it receives it.

B: Set the deck frequency to 80hz or below, and trying to match the frequency back at the sub amp by manually dialing it in.

C: Set the deck to 80hz or below, and set the sub amp frequency to max, using the logic it will only put out around the frequency it is being fed, coming from the deck.

I believe the Concept has a built-in continuously variable 18dB per octave crossover, while the 880 PRS has a 50/63/80/100/ 125/160/200Hz, -6/-12/-18dB/Oct crossover.

The subs are 2 PG RSD 12's.

Any suggestions? Thanks!

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[Jekku 10+ year member]

Use the one on your HU with 50Hz or 63Hz and if possible turn off or set to flat/full the amps x-over. And select the 18dB/oct.

 

[PollyCranopolis 10+ year member]

Use the one on your HU with 50Hz or 63Hz and if possible turn off or set to flat/full the amps x-over. And select the 18dB/oct.

Its not possible to turn off the sub amp crossover. It's built in 18db. I can set the head unit to 18db, which it has been all along. So you recommend just setting the deck crossover, and cranking the amp crossover to the highest point?

 

[Trey803 5,000+ posts]

if u use both crossovers they will run into each other and the end result will not be anything your looking for. I had this same question with my p880 but i can turn my eq to pass on my amp

 

[PollyCranopolis 10+ year member]

if u use both crossovers they will run into each other and the end result will not be anything your looking for. I had this same question with my p880 but i can turn my eq to pass on my amp

Yeah, thats the sucky thing. Theres no pass option on the sub amp at all..just the frequency adjustment.

 

[Jekku 10+ year member]

Yeah, thats the sucky thing. Theres no pass option on the sub amp at all..just the frequency adjustment.

So it's a "nono" for my first attempt. Ok, then I'd go for answer number A. Did I win now? //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

Seriously, that might be the best for you.

 

[PollyCranopolis 10+ year member]

bump.

 

[squeak9798 5,000+ posts]

if u use both crossovers they will run into each other and the end result will not be anything your looking for.

Not sure what you mean by "run into each other" ?

But why wouldn't it possibly be something he's looking for ? How does he know yet if he hasn't tried it ?

To answer your original question; There's no right answer //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

There isn't a right or wrong it. It simply comes down to 1) what sounds best, and 2) your preference.

The only way to determine which is the best option for your particular situation is honestly to try them all. Try having the headunit xover set to a certain frequency and setting the amp xover to it's maximum setting. Then try setting the headunit xover to it's maximum setting and using only the amplifier xover to lowpass the signal. Then try the headunit & amp xovers at the same frequency. Or maybe it sounds best if they are "cascaded"........i.e. try setting the deck to 50hz and the amp xover to 80hz. Maybe 63hz on the deck and 100hz on the amp sounds best. Or maybe 50hz @ 6db/oct on the deck with the amp set to 80hz sounds best. The options here are quite plentiful.

If you were to use both the headunit & amp xover, and set them to exactly the same frequency, say 80hz, and they are both 18db/oct crossovers....the net result would be that the signal would be at -6db @ 80hz (as opposed to -3db using only one of either) and the resulting slope would be the combination of the two; 36db/oct. This is NOT an inherently "bad" thing and very well could be the optimal setting. Or maybe the resulting sound is "best" with them both set to 63hz. Or maybe 50hz.

If you were to "cascade" them, it gets a little more tricky in determining the slope/etc.....but essentially the same thing occurs. The signal will be attenuated by the hu's xover, and then will be further attenuated by the amp's xover. Again, this is not an inherently "bad" thing and could potentially be beneficial depending on different factors.

Also, if you do want to set your amp xover to a specific frequency, it's pretty easy. All you need is a test tone of that frequency and a DMM. Set both the deck's & amp's crossovers as high as they will go so that they won't affect the signal. Unplug the subs from the amp, then play the test tone (in this example, let's say it's an 80hz tone). Measure the amp's output voltage, and turn up the volume until the voltage is 1.414V. Now keep the deck on that volume level and measure the amp's output voltage while decreasing the amp's xover until the the voltage drops to 1.00V. Viola! You now found the 80hz xover point on the amp's crossover.