Amp and headunit

[Nstickler91 0]

So first if I have an 12" Xcon in a sealed 1.5 cb ft box where should I set the subsonic and lpf. And second what is the best deck with three sets of preouts for around 100$

[SS Teacher 177]

Typically you set the subsonic filter to just a little below the Fs of the driver in order to prevent mechanical damage, you shouldn't worry too much with a sealed enclosure. Low pass settings are a matter of taste, I like mine a little higher, around 80 or 90 hertz, it depends on how strong your midbass drivers are.

[Nstickler91 0]

Any recommendation on head unit?

[Sencheezy 689]

SSF all the way down, or pretty close, this you should monitor the driver and adjust accordingly.

LPF, I have mine at 80.

I would suggest checking out some of the JVC units available here at the ssa store.

[S.DeYoung 968]

Check the classifieds I have a nice jvc for sale

[Nstickler91 0]

What should I be monitoring for?

[ssh 924]

What should I be monitoring for?

Over-excursion, but it shouldn't be an issue.

Edited August 8, 2012 by stefanhinote

[///M5 2,833]

I wouldn't use an SSF and for $100 I wouldn't use a headunit of course then you'll need an Ipod or the like.

[dbsupra 69]

I wouldn't use an SSF and for $100 I wouldn't use a headunit of course then you'll need an Ipod or the like.

I understand it is a low frequency high pass filter. Why wouldn't you use one? Because of the rolloff?

[Nstickler91 0]

Well I have an iphone

[///M5 2,833]

Well I have an iphone

A line driver and volume know is all that you need then.

[ssh 924]

Well I have an iphone

A line driver and volume know is all that you need then.

Knob.

I'm guessing is what he meant--he's probably drunk right now.

Edited August 9, 2012 by stefanhinote

[ssh 924]

I wouldn't use an SSF and for $100 I wouldn't use a headunit of course then you'll need an Ipod or the like.

I understand it is a low frequency high pass filter. Why wouldn't you use one? Because of the rolloff?

Frequencies below a ported enclosure's tuning frequency cause a big increase in excursion. Enough that it's possible to exceed the suspension of the driver, and tear everything apart.

So a sub sonic filter (hpf) can be used to attenuate the signal where frequencies are below the enclosure tuning, so excursion will be reduced.

Example:

Ported enclosure tuned to 30hz.

Sine wave of 35hz with an rms amplitude of 500watts causes the cone to move 15mm.

Sine wave of 20hz with an rms amplitude of 500watts causes the cone to move 25mm, and the driver's rated limit is only 20mm.

Set SSF to 28hz, and the 20hz sine wave is now attenuated by 24dB , 10log(x/500)=-24dB x = 45w, and the rms amplitude would be 45watts.

Now that 28hz sine wave has way less power to it, and the excursion will be reduced enough to where it's well within the driver's mechanical limits.

A sealed enclosure doesn't have a port, so there isn't any point where the excursion shoots through the roof. If you were to model excursion vs frequency in a program, you would see that in a sealed box the excursion is relatively linear with less change.

Edited August 9, 2012 by stefanhinote

[dbsupra 69]

Yep I get that. You can even see it on the excursion plot in WinISD. What I don't get is why Sean is against using it. Thanks for the detailed explanation though!

[///M5 2,833]

You don't need it and less is more when it comes to electronic filters. What I don't get is why you think you do

[dbsupra 69]

To prevent over excursion below tuning?

Honestly, I have mine turned down pretty low. If I set it where most people recommend it attenuates higher than I want it to. Perhaps due to the shallow rolloff of my amp ssf.

I know what stress sounds like, and turn down the gain/volume if I hear it. But much like detonation, at that point it may be too late but that's how I choose to roll.

What do you propose to avoid over excursion or is that a non issue in your eyes? It seems the consensus on here is to use it, and being that you go against that I was just curious of your reasoning is all.

[shizzzon 461]

No, he's against it in THIS SCENARIO, not all scenarios.

It's very unlikely anyone would need to use a SSF and a sealed enclosure unless the user was dumping massive amounts of power into the driver.

[dbsupra 69]

Thanks Shizzy

Reading>me. I completely missed the OP was running it in a sealed enclosure. I saw Mr Hinote mention sealed in his explanation, but thought he was just being thorough lol.

[///M5 2,833]

Exactly. Filters not only effect what the pass band is but also change the phase. Less is more IMO.

And yes, my Xcon is in a ported box and I'm using something akin to a SSF. (processor based so I have a HP which for all practical purposes is a SSF other than I can change slope, position to whatever I like).

[Notorious97200 339]

Someone told me here, to put my SSF aound 25 Hz when I was using a big (3ft3) sealed box for my 15" Xcon on 1500 watts.