P38A Wiring in extra speakers from the Lowline model loom.

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Grrrrrr

Grrrrrr

Technician, Bodgit & Scarper Ltd
Posts
19,861
Location
Buckinghamshire, UK. ('95 DT)
Bit of speaker knowledge required!

I have the lowly DT with the Lowline BECM and looms. However, a previous owner has replaced the door-cards from a higher model with extra speakers, the problem being there is no loom for the extra speakers. So ...

How can I wire in these extra speakers? I seem to recall someone saying you just tie them in with a capacitor but not sure where the capacitor goes or what connection goes where. Anyone got any ideas? Be nice to have them all working.
 
I've used capacitors on speaker installations before, primarily to change frequency response of the speakers cable tie a cap on the metal frame of the speaker with one end to the positive and the other to the positive wire. - solder the wire to the capacitor and put a spade on it then cable tie that to the speaker frame (Spider) so vibration doesn't break the capacitor wire.

NB A resistor changes the impedance a capacitor the frequency response

but that was all in a past life
 
What is there in the door? Are we speaking (you see what I did there? :D ) single component or bass/mid and separate tweeter?

What you could do to save a lot of bother is buy a set that will fit in there and bin the originals. The new set will usually come with crossovers which will sort out all your problems with wiring as you simply attach the feed from the door to the main cable, then work in the cross overs and jobs yer uncle.

Halfords have decent stuff.

Component http://uk.jbl.com/car-speakers/STAG...6wZl-taeTwFUo4KcnkgpGMw651Kmq_3-0dBoCaNrw_wcB

http://www.halfords.com/technology/car-audio/car-speakers/edge-ed306-v2-component-car-speakers

JBL's are awesome speakers and with poly carbon or whatever, wont let a bit of damp spoil the shape.
 
+1 . . . the low-line doesn't have door amps, so you can fit whatever you want in there. Just wire them as for any generic stereo.

A Capacitor or Filter is simply there the prevent the bass frequencies from reaching the tweeters. If the speakers include a Crossover, these also reduce the high frequencies to the bass drivers, hence allowing them to focus on the lower frequencies. Same applies for midrange in three-way systems.
 
Sure you thought that was in english!

Capacitors block frequency so presumably also used for compression to stop that high-level whine from electrical interference?

The Halfrauds speakers won't fit as stock. Kind of prefer to keep it looking original unless it is really difficult. I'll have a play when the weather warms up and see where we are. Do I wire extra speakers in series or parallel? Presumably parallel?
 
It was English, but maybe a bit vague. Terminology should be the same as car audio dealers will use !!
  • If you can find bass & mids with co-axial tweeters that will fit into the doors, then you probably don't need any additional filters, capacitors or crossovers.
  • If you want to fit separate Bass, Midrage & Tweeter then you will need a passive crossover.
The doors should have room for 6.5" bass, 3.5" mid (need to check this), and for the tweeters, either buy a pair of HK upper door panels, or use midrange drivers with co-axial tweeters.

No time to google right now, but there are better places than Halfrauds for this stuff, that will be cheaper & better quality. . . . . unless you got vouchers for Xmas ??
 
Easy fix to speaker size, measure yours by removing the speaker and measure it's widest part. They tend to me 10cm or 16cm for most round speakers available these days.

The capacitors are not there to stop frequencies from the engine electrics interfering with the sound, you need a specific one for that, but how old is the vehicle you plan to fit the radio to?

Cross overs are basically to let a big speaker do bass,a medium speaker to do mid sounds (voice and such) and the tweeters sound like birdies singing, but they do the top end (treble) sounds. Bass speakers create low end sounds and the waves can be 30Hz or less (30 waves per second) whereas tweeters can produce up to 20,000Hz....

Anyway, you don't need that stuff, you want probably one speaker per door and I would recommend one component with a built in tweeter bridged onto the main speaker, so basically two in one. Same job, saves room.
 
Grrrrrr said:
Sure you thought that was in english!

Capacitors block frequency so presumably also used for compression to stop that high-level whine from electrical interference?

The Halfrauds speakers won't fit as stock. Kind of prefer to keep it looking original unless it is really difficult. I'll have a play when the weather warms up and see where we are. Do I wire extra speakers in series or parallel? Presumably parallel?
Click to expand...
not parallel unless you know what the ohms of each speaker are and the lowest ohms limit of the amp.parallel reduces ohms/resistance and can over heat an amp if it drops below 4ohms or 2ohms. Model dependent. Series raises the ohms/resistance in the chain of speakers. Hence the reason some power amps have fans to cool at lower ohms! Using resisters as said cap frequencies but be aware of what you use as this can ruin the sound of a good speaker set up! Do some home work into building your own two way, three way or even four way .i.e top, upper mid, lower mid and bass.
or.. A very good quality single speaker or two way setup. This then will be limited by wire quality and the limits of the stereo. Make sure your speaker have a higher wattage than your stereo. Lower wattage speakers can cause a build of resistance that can damage the amp inside.
 
Thanks, chaps. I was hoping a bit of spare wire and some solder could revitalise what is there. The head unit came off the tip so it is not exactly a high-end system. I cannot even remember the make off the top of my head.
 
Grrrrrr said:
Thanks, chaps. I was hoping a bit of spare wire and some solder could revitalise what is there. The head unit came off the tip so it is not exactly a high-end system. I cannot even remember the make off the top of my head.
Click to expand...

I was only using Halfords as a reference.... However, we don't get the same choice up here o_O

Anyhoo, I have this in George and I love it...

http://www.halfords.com/technology/...L3iRAFO9eCgTLhzLWMgCp0zhzVfB4nSpSoaApma8P8HAQ

I am using the standard fit speakers/amp as they are awesome :cool:
 
Grrrrrr said:
Thanks, chaps. I was hoping a bit of spare wire and some solder could revitalise what is there. The head unit came off the tip so it is not exactly a high-end system. I cannot even remember the make off the top of my head.
Click to expand...

off the tip !!

have a look on flea bay you can an alpine cd for £50. also there is a module available so that you can use the steering controls with an aftermarket head unit.
 
Doo said:
I was only using Halfords as a reference.... However, we don't get the same choice up here o_O

Anyhoo, I have this in George and I love it...

http://www.halfords.com/technology/car-audio/dab-car-stereos/sony-mex-n6001bd-dab-radio-with-cd-mp3-player-and-bluetooth?cm_mmc=Google+PLA-_-Car+Audio-_-DAB+Car+Stereos-_-150924&_$ja=tsid:60494|cgn:GoogleShopping|kw:150924&istCompanyId=b8708c57-7a02-4cf6-b2c0-dc36b54a327e&istItemId=ripmrwtim&istBid=tzir&_$ja=tsid:35522|cid:344534764|agid:24344212204|tid:aud-80976661069:pla-211149546484|crid:83789081524|nw:g|rnd:6575321976213770252|dvc:c|adp:1o1&gclid=Cj0KEQiAk5zEBRD9lfno2dek0tsBEiQAWVKyuLcpNRdf4L3iRAFO9eCgTLhzLWMgCp0zhzVfB4nSpSoaApma8P8HAQ

I am using the standard fit speakers/amp as they are awesome :cool:
Click to expand...

You have digital radio up there? I thought you were still on valves?
 
Doo said:
Easy fix to speaker size, measure yours by removing the speaker and measure it's widest part. They tend to me 10cm or 16cm for most round speakers available these days.
Anyway, you don't need that stuff, you want probably one speaker per door and I would recommend one component with a built in tweeter bridged onto the main speaker, so basically two in one. Same job, saves room.
Click to expand...

Agreed that Co-Axial speakers will work, but the mid & high frequencies will be at foot level which is not ideal, so still worth thinking about adding at least tweeters where the HK 1" units usually fit. Generally avoid paper cone speakers . . . such as:

Coaxial Bass drivers are what I put in mine, although I don't care about the colour. They sound good and cones are water resistant.
Coaxial Midrange drivers like these will avoid the need for separate tweeters, BUT the Low Line radio doesn't have midrange outputs !!
P38 Tweeters can be got from eBay at sensible prices.

The arguments about whether to use 8ohm or 4ohm for both Bass & Mid wired in parallel it technically true, BUT does depend on the actual impedance across the audio frequency range, plus what sort of volume you typically run your system at ? Mid-Line stereo seems to have mid-range drivers added, but uses basically the same stereo. Early P38 used AMR2890 in both Low & High Line, so maybe the radio is reasonably tolerant.

Would be interesting to see if the doors contain the wiring for Low-line & Mid-line audio, or if the looms are completely different.

EDIT . . . 3.5" mids probably wont fit. Parts list says 3".

Screen Shot 2017-01-25 at 11.47.00.png
 
Last edited:
Grrrrrr said:
Just out of interest, those using DAB, does it work OK? Is coverage good enough to use on a journey?
Click to expand...

For me, it's not excellent, but it's because even though thousands have bought DAB up here, there is only one transmitter, so when you lose the signal going west or south, that's it, back to FM.

However, saying that, when it's working it's fabulous! When I went to Edinburgh, the choice was epic and no loss of quality whatsoever. If you do go down that route, choose the magnetic antennae as it sits head & shoulders above the stick on windscreen jobs.
 
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