SPL audio gear

[minterbob]

Does anyone have experience with spl gear, i have just bought an sp800 amp {4 channel } and a sp sub box with two 8" subs, {brand new}I am disappointed with the resulting sound to say the least, its as if the amp isn't providing enough juice to the subs, at low volume there is a nice sound and makes you think it will good when turned up but the higher the volume the more you lose definition of the bass,. Its just warbles! like they are twenty years old.
I have double checked everything and twiddled everything that can be twiddled but its still no better.
The one i haven't done is use heavy duty speaker cable as i can't get any till tomorrow, would this make much difference, to the point of what i am experienceing now?.
Any help or advice is greatly appreciated.

[cupragaz]

sorry to tell you mate but my bro bought spl and found they're shit as i've got dragstar and sounds 100% better

[Cupramax]

Have you run a clean supply direct from the battery to the amp on a heavy gauge cable? Is the amp earthed near to where its located... apart from that if its wired up right f*ck knows? You haven't got it wired out of phase somehow have you?

[minterbob]

I have double checked everything and its all wired up correctly, i previously ran a small "boss sound" 200 amp useing the same rca and power cables which were vastly overated for what was needed.
just to be sure when i was double checking i ran a extra cable round the car to the amp which made no difference.
One other thing i have noticed, when i change the bass and treble on my head unit {kenwood 304} it alters the sound at the subs, i always thought that the line out's were direct from the sound chips and went through no other stages at all, is my thinking right or is maybe the kenwood showing its age ?.

[mrkev]

I'd say that Bass & Treble settings would alter the sound unless you are using a head unit that has 'sub out' as well as the normal pre-outs?

[Chester]

Originally posted by mrkev
I'd say that Bass & Treble settings would alter the sound unless you are using a head unit that has 'sub out' as well as the normal pre-outs?

Yeah, definately the bass level adjustment would make a difference, but treble? Nah. Something very wrong, almost like you're not using a cross-over. Are you sending full range to the sub? i.e. Are you setting a low-pass filter to only allow frequencies below a configured frequency to get to the subwoofer?

Most subs only work hard enough when presented with frequencies up to 120Hz, maybe a little higher, but certainly nothing over 200Hz. If you're sending anything higher, especially mid and high frequencies (like 1k and over), the sub will try to move too fast and give exactly the kind of sound you're talking about: warble with no definition.

Try and play sound through the subwoofer only (disconnect rear speakers and fade to back). If you can hear vocals other than very deep, and guitars, anything you'd associate with mid-range frequencies, don't bother going any further, until you can locate a filter switch, and/or frequency control knob. When you make adjustments to this, you should hear that the sound changes drastically. You'll hear that you start cutting lots of mid-bass from the sub and it only produces pure bass punch (kick) and deep bass guitar sounds (or synthetic bass stuff).

The ideal frequency to 'cross-over' to your other speakers is at the point where the main speakers start to deliver good response at the lower end of the spectrum. The correct frequency is different for virtually every install. This will require experimentation. And realistically YOU will need to decide where you want the the low pass to sit, and the amount of gain you want (or amount of power to deliver to the sub). This is a personal taste and is neither right or wrong, as long as it doesn't put excessive pressure on the sub, or excessive load on the amp.

If you do not have a cross-over on your amp, and your head unit does not provide a facility to directly drive a sub-amp, then you will need to purchase a line-level cross-over or low pass filter, which goes between the connection from your head unit and your amplifier. I think this is unnecessary, causes clutter on your installation, and most good amplifiers should have this facility anyway.

Alternatively, some people do not use rear speakers. Most Pioneer head units have something called FIE (Front Image Enhancer). All this does is exactly the same thing as a low-pass filter, but just to anything connected as rear; but this can sound, well, 'orrible!

Let us know how you get on...