I have finally finished installing my amp/sub, got a few questions.

I know the best way to set up your own system is to have a listen and go with what you like best but Id like a few pointers/advice.

System:

Alpine HU 4x60W(not sure if RMS) CD/MP3 player.

Stock rear speakers

Stock fronts at mo but infinity 6512si (i think) shallow fit coax speakers (fitting next W/E once i have a soldering iron)

Infinity 300w (220WRMS bridged) amp

Alpine type S 12" in a letterbox ported (prob bandpass actually, the port starts at the back-top corner)

Questions.

1) Whats the best low pass crossover freq for the sub?

Should I be after drum kick only, or bass guitars or what?

Actually i think a ported 12" may be over egging it, im not into poundy music, (punchy drums and bass guitars yes!) But it was a good deal at the time.

Wired as 8Ohms, thought of changing to 2Ohms, not sure what benefit this would produce as it will go plenty loud enough!

2) Front/Back balance. Is it worth toning down the rears and taking advantage of the nice fronts?

3) New front coax vs bass, just not sure what I should be expecting from the fronts.

Previously had the bass turned up a bit on the HU. Should I now turn it down below say 150Hz, and have the sub take over?

Im assuming this will make the midrange perform better.

What freq should i have the sub dealing with? sub 300Hz? 200Hz? 100Hz? 80Hz? or even less? Ive noticed on my home system bassy guitar makes it down to about 80Hz.

Thanks for your Know-How

Jono

Supplemental:

Is it worth keeping my eyes peeled for decent rears?

Should i just slightly upgrade the stock ones?

If I got decent/pricey replacement rears, do they actually make much difference?

With the stock speakers I have treble problem, Its too harsh and the rears are disconnected.

With decent treble from the rears (coaxially) do people think it will help solve the crap treble problem?

Jono

Hi,

Looking briefly @ the specs of your amp / sub, you wont have a choice of ohms to run it at, the sub is a 4ohm, and running it via the amp in bridged mode will only play it at a 4ohm load...

You got the rite idea of reducing the vol' on the rears as not to mess with your front soundstage...

If u dont like loud pounding bass, i think a ported box maybe a little too OTT for your tastes, just take your time setting up your install, using a variety of music, but make sure u keep all the EQ settings flat, whilst tuning...

Goodluck, and let me know how u get on...

I cant wait to put my current setup in my Octavia Estate when i get it ! Woo hoo !

I do have a choice.... 2x 4Ohm coils = either 2Ohm(parallel) or 8Ohm(series, currently)

I wonder if stuffing the letterbox sealed with some dense foam etc will tighten up the bass? or is that asking for trouble?

Jono

Ahhh, sorry chief, i didnt realise the S type subs can had with DVC's...

Is your amp 2 channel or is a mono amp ?

Stuffing the port can be done, but not recc'

It would prob cost around £30 to have a new sealed box made, nicer, tighter, deeper, and more controlled bass...

But by all means, give it blast 1st, as the saying goes,

"suck it & see..."

Let me know what amp u have...

Cheers M8

I think, even if u do manage to wire it up (kinda) safely using both voice coils, if it reads 8ohms, its gonna half the power of your amp...

i.e 220w rms into 4 ohms... so if its reading an 8ohm load, its gonna deliver 110w rms...

I think, about 95% sure on that...

double resistance=half power

so running your sub as 8ohm will only get 55W from your amp(the 220W quoted will be at 2ohm if its 2ohm stable) so definitly not not recommended

on my setup i have the cross over set t 85Hz for the subs so they don't get a lot of the mid

i have the same 12" type S but i have 4 of them:eek:

set to a low-ish Hz they have a nice tight punch but not loads of mid rumble

by the way i have mine in sealed .75 boxes tight as!!

Its the infinity 7502i ( I think) 220W RMS @ 4Ohms Bridged

Its second hand so I dont have the manual.

AFAIK its not rated as 2Ohm stable, but running it at 8Ohms at half gain seems fine to me, loud enough for now, until bass-creep sets in (where you always want more...)

Would it be safe running at 2Ohms as a trial? Do amps cut out and cool down, or just die?

I mean running at no more than half power on 2Ohms, does this give tha amp the same stick as full power on 4Ohms (i.e same power output wattage wise)?

Jono

Hey Jono,

I reckon, your best solution would be, inform us of your budget you're willing to spend in order to get things sounding how u like...

I would definately avoid running that sub / amp combo @ 8ohms, something will either get damaged, and tbh neither item will truly shine, which is a shame, because you're obviously thinking about how you want your install to sound, as oposed to how much volume it pumps out !

But if i was u, i would invest in a nice set of components for the front, leave standard speakers in rear, but fade them out, use your infinity amp to power the front comps, and invest in a monoblock to power your Sub, making most of its DVC capabilities... and lastly, if your're not enjoying the bass then, invest in a nice sealed box, either .75 or 1cu/f...

That would be a nice tight souding setup...

If you're stuck on which comps / amps to choose, give us a shout, as u may have guessed I do love my music !

Take it easy chief !

Well I have purchased a bunch of stuff to have an experiment with, I know the best way would be to buy components that are matched and complement each other, but that probably means buying new, and spending circa 3x what I have spent.

I reckon the Infinity fronts will serve me well, shallow fit coaxials simply for ease of installation.

Im just wondering whether to get some cheap ~£20-40 new cost rears, or if its worth aiming for ~£75+ ones.

Im not sure I can be arsed wiring speakers from a boot amplifier, its taken me long enought to take the car apart once, I dont fancy doing it again in a hurry!

Once all my stuff is fitted, I reckon I will have spent enough for now, and Im mainly after advice on how best to set it up.

Im assuming running Sub and Amp at 8Ohms will just mean that only 110W RMS is avaliable for it? (which is prob enough)

Does this reduction in power mean that the amp isnt likely to clip, even at high vol/gain or does it not work like that?

I have always worked on the theory that amps shouldnt be run beyond 50-75% max power.

Jono

HEy Jono,

If you fancy a new sub, this would be an awesome choice, i bought one of these b4, and was really really impressed, cant fault the SQ and build quality of it !

http://caraudiosecurity.com/shop/product/products_id/1424.html

You could put these comps in the front, running off your infinity amp...

http://caraudiosecurity.com/shop/product/products_id/1555.html

and use this amp bridged into mono to power the sub

http://caraudiosecurity.com/shop/product/products_id/2910.html

Just an idea...

If you wanted to keep your Type S sub, then i would go with this monoblock

http://www.caraudiodirect.co.uk/product_info.php?products_id=4626&cadid=903fed6402847b367a74ea49d8137434

and combine that with the comps i recc' above running of your infinity amp....

Hope thats not too complicated !

Stu.

I have finally finished installing my amp/sub' date=' got a few questions.

I know the best way to set up your own system is to have a listen and go with what you like best but Id like a few pointers/advice.

System:

Alpine HU 4x60W(not sure if RMS) CD/MP3 player.

Stock rear speakers

Stock fronts at mo but infinity 6512si (i think) shallow fit coax speakers (fitting next W/E once i have a soldering iron)

Infinity 300w (220WRMS bridged) amp

Alpine type S 12" in a letterbox ported (prob bandpass actually, the port starts at the back-top corner)

Questions.

1) Whats the best low pass crossover freq for the sub?

Should I be after drum kick only, or bass guitars or what?

Actually i think a ported 12" may be over egging it, im not into poundy music, (punchy drums and bass guitars yes!) But it was a good deal at the time.

Wired as 8Ohms, thought of changing to 2Ohms, not sure what benefit this would produce as it will go plenty loud enough!

2) Front/Back balance. Is it worth toning down the rears and taking advantage of the nice fronts?

3) New front coax vs bass, just not sure what I should be expecting from the fronts.

Previously had the bass turned up a bit on the HU. Should I now turn it down below say 150Hz, and have the sub take over?

Im assuming this will make the midrange perform better.

What freq should i have the sub dealing with? sub 300Hz? 200Hz? 100Hz? 80Hz? or even less? Ive noticed on my home system bassy guitar makes it down to about 80Hz.

Thanks for your Know-How

Jono[/quote']

1) Changing from 8ohms to 20ohms does nothing for you except increase impedance. To go 'plenty loud', you need to leave it at 8ohms, upto 2 ohms max if your amp is capable of handling that load. Car audio systems are designed to run at these impedances for a reason.

Out of the sub, you need bass. That's what it's designed for. You should keep in mind that a subwoofer is the missing component in most systems that complete the bandwidth of audible signals. I recommend you set it at around 50Hz-70Hz. The depth of guitars will bleed through with your component speakers, giving you a full sound. The kick drum will also do the same, and the bass will just own. Bear in mind what you DON'T want is vocals bleeding through, which is why you should set the sub at any of these frequencies. Vocals come through at about 80Hz. I have my subwoofer set at 50Hz, and I have rear 6x9s that give me the audible kick.

2) Set your front/rear balance to your own taste. Ideally, you would set it so that the music (comes from all over), but you could again just leave it as it is. That's how I have it anyway.

3) If you can set the cut-off frequency for your coaxials with your headunit, then yes, cut them off at about that frequency..or actually, even better, cut them off at 90Hz. You want a full-on sounding system, so if you set your subs to cut-off at 50Hz-60Hz, you'll want that kick coming in from your system and defined bass, which perform at around the 120Hz mark. From what you tell me, you have a two-way system tweaking capabilities, which is amazing

My two cents

your amp is too small to start with, thats a 300W RMS sub and 220W isn't really enough for it and by running it at 8ohm is going tocut the power its getting again so to get the same punch that you would at the correct wattage input you will be over driving the sub and blow it eventually.

people get it the wrong way round all the time and think that amps constantly put out the max power when infact its the other way round and the speaker is constantly trying to draw its rated power and if the amp is too small it will strugle and not keep up.

if you run the sub at 8ohm you will knacker it eventually.

from what have found looking round the internet the amp isn't 2ohm stable when bridged so running the sub at 8ohm will mean its only getting 110W RMS which is way under powered. you bought the wrong sub mate, you have bought the SWS-1242D and you should have bought the SWS-1222D wich is exactly the same but has 2x2ohm coild instaed of 2x4ohm coils which would have meant you running the sub at 4ohm instead of 2ohm.

The sub and the amp wern't bought new, they were bought cheap second hand anyway from separate sources.

I just picked them all up as an experiment with the intention of tweaking and upgrading them later and selling on the bits.

Does anyone know for certain if I am able to run the amp gently (i.e not full power) at 2 Ohms at all? Im assuming as the current will be higher it will warm up more. Do modern amps just cut out when they overheat, then I can go back to the drawing board.

Jono

Oh my...I though you wrote 20 OHMS...I din't see you meant 2Ohms...and I was wonderin' what you were on about...almost the impedance of jumbo headphones...

Bengie, if I'm correct, given the fact most of them start off with a load of 4 ohms, they should be able to go down to 2ohms shouldn't they?

depends if the amp is 2ohm stable

running a 2ohm load on a 4ohm will mean it will get hot quicker, where is your amp mounted?

You talkin' about me?? I have it mounted on the back seat, and I know it gets pretty hot in that tiny boot, so I took precautionary measure, and had a stinger fan installed, which is amazing:D Stick your finger in it and you really will bleed (happened to my colleague), so I have no worries of thermal protect kicking in.

I'm running 4 ohms as well, not 2.

Its in the boot, attached to the sub box.

Assuming it just means itll get hotter quicker and nothing more sinister I might try it at 2Ohms and revert if its heating up or even cutting out.

Incidentally, I think I might have picked the wrong wire to attach my remote power on to.

I attached it to about the only spare connector, a blue wire, the same colour as is attached to the aerial booster.

Should it be attached to a different colour wire?

(alpine HU)

The power indicator on the amp is always lit, is this just cos its always attached to the battery? or should it go off without the HU on?

Its worth noting, i hear the noise of the cone moving when i turn on the HU, is this a sign that I did pick the right wire after all?

Jono

sounds like you have it connected to the wrong one mate as the amp should switch off when the ignition is off.

The easy way I realised is just to disconnect the remote from the Amp and see what happens.

If the light stays on regardless of HU status then its just to signify that its connected to the power...

If it goes off however im a bit more puzzled. There was only one free unconnected wire coming out of the wiring block. Anyone know what colour the one im after is likely to be?

Jono

if unsure then by a relay and connect the remote wire to the permanent live vis the relay and have the ignition feed switch the realy

Hmm that requires snipping into the ignition lead, Im not sure im into that.

Just wondered if anyone with an alpine amp can remember which lead they used for the remote power.

My manual is lost with a million other house-move casualties.

Jono

The remote wire is a blue/white striped one from the HU.

Do you know which model your Alpine head unit is?

Manual for CDA-9813R

You can search / download in pdf format the manual for your HU if it's not the 9813 here

If you have a multimeter, try measuring the voltage output of the blue/white "remote" wire coming from the ISO power block of the Alpine, and you should get 12V when the HU is on, and nothing when off.

Thanks mate. I found a copy of the manual but it was corrupted, that ones fine!

Yeah, a multimeter is lacking from my toolbox, as is a soldering iron at the mo. Must nick my Dads.

I didnt see a white/blue wire in there but it lools like an explosion in a spaghetti factory, Ill have to sort it out in a couple of days after my deadlines.

I should have the autoleads speaker plug adaptors by then, so in go the Infi 6512 shallow fit

Incidentally, anyone fitted component rears at put the tweeters on the plastic shelf where the mids would mount?

Jono

I didnt see a white/blue wire in there but it lools like an explosion in a spaghetti factory, Ill have to sort it out in a couple of days after my deadlines.

Yup, imagine what it's like in my fabia where there's even less space and I have an extra two loops of ISO cabling, sat nav wires, 4 pre-outs to amps in the back :eek: A bit of a tight fit to get it back in.

It's well worth taking out the glove box so you can feed your arm round the back. If you haven't taken the box out, do so, but be wary of the wire going to the light - it's often short and easy to break.

Incidentally' date=' anyone fitted component rears at put the tweeters on the plastic shelf where the mids would mount?

[/quote']Up to personal preference, but I wouldn't bother too much with sound from the rear unless you often carry rear passengers. You'll get a much better soundstage if the sound comes exclusively from the front.

I haven't bothered changing my rears and have them faded out to the front by 90% odd. That just leaves me with rear fill which is more then enough for my ears, anyway