Car equipment

[ROD]

Can someone explain the vagueries of car stereo? Basic explanations please!.........Ive got an old cd head unit ,and new 6x9 speakers in rear ,with orig equipment (crap) speakers in dash.......What do I need to replace the dash spkrs?............... I keep seeing amps and bass boxes s/h for sale,but aint got a diddly squat what is good/bad /required etc. .................. whats "bridgeable" mean?....... Do I need bridgeable? ...what are component speakers?...do I need them?............Im dubious about buying anything s/hand,even if it was a complete matched system! .............I guess I need a new/better head unit that plays mp3 stuff ,seeing as Ive got all my music at home in that format?..........Im aware that one persons idea of good ,is anothers idea of junk ....Please be gentle with explanations!
    Thanx

[catboy]

rod, is this for the merc?..  if so, prob best to get co-axial for the front, unless you're ok with having seperate speakers popping up out the dash..  there are basically 3 types; single cone (like a house speaker or cheaper car speaker) co-axial (seperate tweeter built into the standard speaker unit) and "seperate" or component (which is two completely independant speakers with a cross over. These are great for seperating the soundstage between the mid and high's but unless you have somewhere to put the tweeter they either look odd or messy!..  In the 123 (and 124) merc's the speakers sit in the top of the dash facing upwards which projects the sound into the screen and back at you, which actually works really well..   there is space in there for a low-ish profile co-axial behind the standard grille, i think i have kenwood co-axial's in mine and they work really well..

as for the amp side of things, if you are running a sub you either want a single channel amp or a bridgeable multichannel amp. basically "bridging" combines the + of one channel and the - of another to give you a single higher powered output (a bit like two batteries in series..) you need to have a bridgeable amp to do this though, its not enough to link the un-used - and + of the two channels of a non-bridgeable amp with a piece of wire..

if you are considering getting a new head unit, i would look for one with a decent output. I currently have a head unit with 4x 52w output, whcih is enough for me to run my speakers..  Having an external amp would give better sound quality but in a 123 i don't think its really gonna make a lot of difference..  

personally i have a sony mp3 head unit, a pair of co-axial kenwood speakers upfront (not the best but they fit) and a 12" jbl sub in the boot powered by a 200w RMS bridged 2-ch amp. This is pretty loud (80mph all windows open it still sounds loud    ) and its in a big box (about 15" x 15" x the width between the rear wheel arches! ) so drop's really low but still quite punchy..  It does have a bit of a dead spot though in the transfer between the sub and mid cones in the front speakers, but I can't really bring myself to cut holes in the rear shelf and fit some 6x9's!..  you shouldn't have that problem; the larger mid-cones of the 6x9's should nicely cover that range..

i am considering partitioning my box so 3/4 its width is for the 12, and fit an old JL audio 10" sub in the other part, running off a seperate amp but with a low-pass filter to the 12, and a high pass for the 10..   not sure whether this will work, but might help!

If you're looking for 2nd hand kit be careful, I've purchased 3 amps from ebay over the years and only one worked..  usually something simple to fix, but it might be easier and as cheap to buy something from an advertiser doing a deal in maxpower..   also for amps, try out the SPL-X range from motorworld. They're pretty budget but do a decent enough job..  you can get 2, 4 and 2ch bridgable amps from them and they're 35 - 60 ish quid last i checked..   Also consider one of the older monoblock kenwood or rockford amps from ebay; they're rated about 150 - 250w RMS which is usually too small to get the attention of the chav's who want 4 figure power outputs (usually for no reason! )

if you want to know anything specific post back and ill try to advise; im sure others will have lots of ideas on kit and sources too!

b

[Bone]

for advice i would recommend http://www.talkaudio.co.uk/vbb/ also http://www.the12volt.com/
for a good quality basic system you need head unit, front components (preferably amped) and a sub.
generally speaking 6x9's in the back are a bad idea, they drag the sound stage back and when you have a sub in the boot the pressure makes the cones bounce....
i would recommend a 4 channel amp and bridge 2 of the channels to run the sub leaving the last 2 channels to run the front comps, generally speaking the amps in head units are tiny, they may quote 50x4 watts but in real life even they are more like 8wrms which is not enough to run a set of comps effectively.
as far as brands go let me know your budget and i will point you in the right direction
if you need any more specific advice give me a shout

[ROD]

Right ,thanx guys! Hmmmmm...........I just gotta read those posts another 50 times ,and it might just sink in ! (Im old !)
 A few more Q's............... Motorworlds website is down ,or gone completely. What about Halfords? *runs for cover*! Got a branch local to me .Bearing in mind Im not after perfect sound ..........I know the sub has to be in a certain size box etc ,but is it poss to fit it in an irregular shaped box,so that I can make it look more custom,Im thinking a 12" dia tube about 30" long sealed all round ,with the sub mounted on the side of it ? .....Cos of my trunk configuration I have a very large void(about 12") between the rear of the back seat and the petrol tank,is it worth trying to put the sub in there and hide it?...........I have 6x9's on rear shelf,mounted on slightly raised plinths (tight space due to rear screen slope) BUT I didnt cut out the steel shelf underneath . I need to do this ,as the speakers seem to vibrate with the vol turned up ,even on my crap head unit! I had 6x9's in the steel parcel shelf of my Amazon ,open into the boot ,they sounded really bassy............Cos Im not after perfect reproduction of sound ,i'll start with replacing the dash spkrs first,with coaxials.......Are subs with built in amps any good?(I could strip a s/h one down and mount it in said custom 'tube' ?)
   thanx for the help!
 "UPDATE"..Just been given a pair of newish 6x9's ..would these be ok in the front ,mounted in door builds,or under the dash? BTW ..my son just told me he sold a nearly new mp3 compatible head unit on e bay last week for £30! dont you just love things like that? !!!

[Bone]

motor world has gone bust, i would try and stay clear of hellfrauds if possible, most of my kit comes from http://caraudiodirect.co.uk/
if you can get 6x9's in the doors then go for it, space might be an issue though, if they are under the dash they will make the sound stage very low, the shape on the sub box doesn't matter to a certain degree, the perfect shape is a sphere as there will be no standing waves, but in most cases any shape is fine. it's getting the size right (and if ported the tuning freq as well) that matters...
don't forget to budget for sound deadening

[ROD]

ly nSound deadening in the speaker box? Ive actually got a shere ,about 24" diam.Its thicj plastic ,would this be ok to use with sub mounted in the side of it ? Maybe use expanding foam for deadening in the sphere? I really need to go to a shop with someone who understands all this gumf,so they can choose for me!

[Bone]

if your putting speakers in the door then you will need to deaden the doors, there are loads of products available ie brown bread, dynamat ect
the sub enclosure needs to be as stiff as possible to put in perspective 18mm mdf is failry common for sub boxes but even that can flex with a large box or with enough power, and a 24inch dia seems a little on the large side for a sealed enclosure.
On www.talkaudio.co.uk there is a very good FAQ section, i would strongly recomend have a read through some of it.

[ROD]

Gave this some thought ........First I'll get a pair of coaxials that fit into the existing dash holes,mainly cos I cant be arsed with cutting/deadening the doors for the 6x9's.Then I'll cut out the metal parcel shelf below each of  the existing rear 6x9's............Xmas is coming ,and the family want to know what I want.....so I'll go for a head unit!(maybe an amp as well ,If Im lucky)!!
    If anyone else has got any ideas on what Im doing ,please shout ! (cos I havent   )

[fatdaddy]

not rocket science Rod  
gen up as you are and go for it, you're a man with common and practical sense, you'll be OK.

I haadn't doen an install before the original one on Max first time round. All I did was ask as you are and look at others then did what i thought was right. We won under £1000 [was early 90's   ] sound-off at Beetle Bash that year, think it cost me around £450 in bits and ran tape when the others had disc..... just care and research.

[voicey]

i had alpine custom fits in the dash of my 123, sounded gread, not too expensive and hid behind standard grilles

[catboy]

one thing to check with the head unit; can you get disks in and out when its in park, and can you flip the face down (assuming its a flip-front one) when in park..  sounds stupid but its a pita if you can't!..  my current ones fine, but the head unit in my old 4 door you couldn't do either and it was annoying..  probably just me being anal  

[ROD]

Youve got a point there Ben! If the cds in my existing unit ar protruding ,they often get bent over when I put it in park! Forgot about that!

[catboy]

its a small thing, but it really gets on my tit's!..  also check it doesnt protrude down too far or the ash-tray catches when you open it  
the only thing my head unit does that annoys me is if you plug the sat nav into the fag lighter it hits the vol knob..  i might have to add another 12v socket in the glovebox over the winter..