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Joined: Mar 22 2016
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So this is one for the stereo nerds, lol,,
I’m looking at dumping the sub box and dsp amp, fixing some timber to the cover panel for sub
and putting a decent boom boom speaker in with a bigger amp.
I’m going to replace all the speakers throughout the car as well.
The question is, can I run the speakers the old fashioned way directly from the back of the stereo,
or do I still need to run them through the out stations, obviously I’m going to have a lot of fun
Joining up with a supply for the amp etc, I want to keep the cd changer if possible, and still have
control of the volume from the steering wheel, any help is appreciated..

( ps, working dsp amp ( with sat nav ) going up for sale soon )

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If you've got the DSP amp, you haven't got the outstations (amps) in the doors, speakers in the doors are wired directly to the DSP amp. So you can run from the head unit to the speakers by linking the wires where the DSP amp used to be. The problem is that the DSP amp is only fed with L and R signals, no front and rear feeds. Marty will no doubt confirm but I'm not sure there is a pair of rear outputs from the head unit, my understanding of it is there is the L and R and then a data line so the output is split front/rear in the DSP amp depending on how you have told the head unit.to divide it.

If it's working why are you removing the DSP amp? I can't see there's anything to stop you simply replacing the existing sub amp and speaker with a different one.

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Joined: Jul 12 2016
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You'd need something to power each of the speakers. No headunit will have enough outputs to power as many speakers as these cars has. Most headunits have 4 speaker outputs at most. FR, FL, RR and RL.

When I took my DSP out and replaced it with the door amps I had to run extra wires for the RR and RL feeds. It wasn't really any hardship - it's just four lengths of speaker wire too the boot. I also made up the attenuators to sort the signal from the headunit in to something the amps could use.

I'm getting a lot of whining noises, crackles and a bunch of other noises as well as various speakers dropping out at random. I recently asked on an audio forum about the best way to replace the whole lot with an aftermarket set up to eliminate these problems as I'm reasonably confident the issues lie with my fairly poor soldering skills. There's a lot of wiring connections involved in taking the DSP out and using door amps.

I asked how best to preserve all of the speakers in the car as I wanted to keep the separate tweeters etc. I was told to get an aftermarket DSP amp and power each speaker directly (cutting out the way the front tweeters are linked to the mid speaker).

Powering each speaker individually means you'd need 10 channels plus one for the sub. There would be three channels per front door (tweeter, mid and bass), two channels per back door (mid and bass) plus one channel for the sub.

Even keeping the tweeter and mid driver in the front doors linked means you'd still need an 8.1 channel amp. 8 channel DSP amps seem to start at £700 and go upwards from there: http://caraudiosecurity.com/amplifiers-eq-car-amplifiers-7-8-channel-amps

I quickly gave up on the idea.

The other suggestion was 3-way components in the front doors and 2-way components in the rear door and a 5 channel amp. The issue with this set up is, I think, finding a set of speakers that are all the right sizes for each of the mounting holes in the car. I think at least the tweeters in the front doors are a fairly unusual size.

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I have to say... I really like the quality of sound in mine - but it has door amps from factory. Marty's DSP amp replacement using door amps (I'm guessing what you've done Rutland) should sound just as good if the wiring is up to it.

I'm feeding mine with antennuator circuits from between the speaker level outputs of my Pioneer head unit and the door amps. For the sub though I've binned the original setup, put a Pioneer amplifier in the space where a DSP amp would be, and then have a 10 or 12" sub in a box that sits in the load space, connected with a speakon connector. That way I can quickly unplug it and take it out should I need the space to really fit the car up with stuff.

But the original speakers are matched well to the door amps. I've had to replace a few that were seized likely due to corrosion when I got this P38, and if others fail in the future I'll get used replacements again.

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Joined: Sep 14 2016
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Easiest way is to start over. Only thing I'd keep from standard are the steering wheel controls. Which ideally means a head unit that natively works with them or can be linked direct to the buttons. But I think you already have a tablet in the dash so maybe that can't be done.

Use a compatible remote power amp and compatible speakers. Link in with fresh wire as per the amp and head unit books. Job done. If it doesn't work as it should at least troubleshooting will be as per the car and audio system books not worrying about whats wrong with the linking between old and new wires. With the P38 level of electrical complexity you really don't want to be altering things and forgetting WTF you did.

Been there, dunnit on other vehicles for other folk and I know that a clean install is the fast way. Next person who asks me to sort car audio is getting their vocabulary expanded. Haven't done that sort of thing for about 15 years which suits me just fine.

One thing I've never understood with this DSP lark is why there are no universal "program for your car" replacements. So long as you have two clean audio inputs, the right number of amplifier outputs and compatible connectors, whether direct or via an adapter cable its all just a bunch of class D amplifiers driven by software. If anyone thinks there are any significant internal hardware engineering details, beyond specific components, between the various manufacturer and model specific DSP boxes I've got an excellent cash deal on bridge for them.

Clive

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RutlandRover wrote:

You'd need something to power each of the speakers. No headunit will have enough outputs to power as many speakers as these cars has. Most headunits have 4 speaker outputs at most. FR, FL, RR and RL.

That, along with a sub output, is all you need. The DSP feeds the bass speaker on a separate feed to the mid range and tweeter but you could just parallel them up or run via a 2 or 3 way external crossover. So the FR output would be connected to all 3 speakers in the FR door. I suspect the DSP amp has the crossover built in so rather than it having 8 outputs, it still only has 4 but with the front feeds going via an internal crossover and giving a bass output and a mid/tweeter output from the same input. Having 3 separate speakers is no different, in fact preferable, to having a 3 way component speaker. Most cars these days run 3 speakers per channel so any head unit should be capable of powering them.

What we don't know is what you are trying to achieve (other than having window rattling bass). I know you've got the Android unit installed but you've retained your original Alpine head unit. Are you planning on retaining that or are you going to change that too?

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Sloth wrote:

I have to say... I really like the quality of sound in mine - but it has door amps from factory. Marty's DSP amp replacement using door amps (I'm guessing what you've done Rutland) should sound just as good if the wiring is up to it.

Yeah, that's what I've done. I'm pretty sure the issues are from my wiring/soldering (in)ability. There a whine that increases with engine RPM. There's a constant crackle/white noise from the rear passenger side. I'm not sure if it's as far back as the sub or if it's the rear door. I feel like it's right back in the boot though. It seems to be related in some way to the lights. If I turn the lights on, it stops. If I brake, it stops. If I indicate, it stops and starts with the indicators.

All of the speakers drop out from time to time and it's a different one each time. They come back if I go over a bump in the road. The driver side tweeter crackles and there's a sound through one of the speakers like a spring pinging when I open a door.

When it's all working it does sound great though :P

Gilbertd wrote:

That, along with a sub output, is all you need. The DSP feeds the bass speaker on a separate feed to the mid range and tweeter but you could just parallel them up or run via a 2 or 3 way external crossover. So the FR output would be connected to all 3 speakers in the FR door. I suspect the DSP amp has the crossover built in so rather than it having 8 outputs, it still only has 4 but with the front feeds going via an internal crossover and giving a bass output and a mid/tweeter output from the same input. Having 3 separate speakers is no different, in fact preferable, to having a 3 way component speaker. Most cars these days run 3 speakers per channel so any head unit should be capable of powering them.

I'll admit that I don't much at all about how to wire car stereos. I have a feeling I might have asked my question the wrong way on the forum I used due to a lack of knowledge on my part. I asked specifically how to retain a separate bass, mid and tweeter in the front doors etc rather than how best to replace the set up and retain SOME KIND of bass, mid and tweeter.

I understand what you're saying about the DSP splitting the feed between multiple speakers but isn't the DSP is also an amplifier that outputs more power per channel than a headunit to achieve enough power at each individual speaker?

The question at the top of the thread was about removing the DSP amplifier, fitting a subwoofer with a dedicated amp and powering the speakers directly from the headunit (unless I've misunderstood the question).

Would using one channel to power three speakers not reduce the amount of power each speaker gets meaning you lose overall volume and/or quality from each speaker? IE: if you split a 45w (the power my Android headunit claims to output per channel, unsure if that's peak or RMS) channel to three speakers wouldn't you then only have 3x 15w speakers? This is the assumption I made that led me to wanting power to each of the speakers.

If you remove the DSP from the system and use 4x headunit outputs to power 10 speakers wouldn't you end up with underpowered speakers?

Again, I don't have a great understanding of this stuff so I could well be very wrong which would explain why I've seemingly come to the conclusion that it's difficult to do what I think needs doing :P

Gilbertd wrote:

RutlandRover wrote:
What we don't know is what you are trying to achieve (other than having window rattling bass). I know you've got the Android unit installed but you've retained your original Alpine head unit. Are you planning on retaining that or are you going to change that too?

I'm not looking to win any bass competitions or blow out my toddlers eardrums :P

I'd mainly like to just retain the audio quality of the original setup (or perhaps even improve it) but without the whines, crackles and drop outs that I have now.

I haven't retained the Alpine headunit. All I have is the Android headunit where the factory satnav used to sit.

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Joined: Sep 14 2016
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Looks like what you want to do is basically option 2.2 at the bottom of this page : http://ddaudio.com/car-audio-upgrade-guide/ . US site but nice pictures.

So all you need is to find a suitable DSP replacement amplifier, appropriate speakers and, maybe, an intermediate signal processor. If you need control adapter wiring these folk seem to have what you need https://incartec.co.uk/Landrover/Range-Rover-II-P38A/Stereo-Upgrade-Double-Din/Kenwood-Double-Din/0 . Earlier on that site they imply that they have drop in solutions for the P38 but nothing useful comes up.

Any good car audio specialist ought to be able to sort you out with a new DSP and speaker set.

10-20 years ago I'd have done something like Martys door amplifier arrangement with an extra amp for the big speaker. But when you can buy it all sorted in a box its hardly worth the effort. Connectors and plugs are the primary issue.

Clive

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RutlandRover wrote:

Would using one channel to power three speakers not reduce the amount of power each speaker gets meaning you lose overall volume and/or quality from each speaker? IE: if you split a 45w (the power my Android headunit claims to output per channel, unsure if that's peak or RMS) channel to three speakers wouldn't you then only have 3x 15w speakers? This is the assumption I made that led me to wanting power to each of the speakers.

No, because you are spreading the power between the speakers so the amount of air they can shift will actually be greater than having one speaker, giving more volume not less. The output of the amp is the full range of frequencies but the largest speaker can't move fast enough to reproduce the higher frequencies so they get lost. Equally the tweeter only has a 1" cone so works beautifully with the high frequencies but can't cope with the bass. The midrange then deals with the bits in between. Now you can just rely on the fact that the speakers won't respond to frequencies they can't really handle but it can muddy the sound as they will still try to, so the high frequencies will damp the cone in the bass speaker. This is where a crossover comes in. It is a set of filters so you feed it with the full range and it splits it into the three ranges, bass, mid and high which are then fed to the individual speakers. The non DSP mid line system (fed directly from the head unit) uses capacitors in series with the midrange and tweeters to block the bass frequencies while the high line system with the separate door amps uses a single amp but with a built in crossover so the bass is fed to the bass speaker and the rest is fed to the midrange and tweeter with a capacitor in series with the tweeter to keep the lower frequencies out. So what you have is 4 amps, one for each channel (FL, FR, RL and RR) with inbuilt filters to split the output between the different speakers.

The DSP system does much the same only it is controlled by a data line (so while it is only fed with a 2 channel stereo input, the data tells it how much to send to the front and how much to send to the rear) and can also alter the sound to give different effects by putting minute delays in outputs to make the soundstage move and add preset equaliser settings.

For the sub you just have one further amp, sometimes mono to drive a single speaker, other times stereo to drive a pair (or a stereo input that is then combined to drive one speaker). Looking at example 2.2 that Clive linked to, they are using the original head unit, passing it through an attenuator, which may also convert between balanced and unbalanced signals. Unbalanced means one leg is grounded, so a 1V peak to peak signal would be between 0V and 1V, whereas the same 1V balanced signal would vary between -0.5V and +0.5V. From that they then feed a 6 way amp, almost certainly incorporating filters, to drive the 4 main channels and a stereo sub. Virtually identical to what Marty's 4 door amps substitute for the DSP amp solution does only it doesn't include the sub amp as that was separate in the first place. It'll work fine as a substitute for a dead DSP amp and retaining the original head unit but when you start feeding it with signals it wasn't intended to be fed with, then you are in uncharted territory.

I suspect the reason for your whine, although not the pops and crackles which as you say are down to your soldering skills, is because the outputs from your Android unit are unbalanced but the amps are expecting to see a balanced input. Careful experimentation with grounding is needed to sort that and possibly also some filtering on the supplies (I've got a few boxes of FX1588 ferrite cores if anyone can use them or even knows what they are...).

However, Chris still hasn't popped up and told us what he is trying to achieve......

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Joined: Mar 22 2016
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So in theory, as I’ve got connections for a sub out, and an aux, I could put the cd changer to the aux, and fit a new more powerful sub in the boot.
As I’m not using the nav part of the dsp amp could I swap to the cheaper one ? ( non sat nav dsp )
That way selling mine on pays for most of the upgrades I want 😁

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Gilbertd wrote:

RutlandRover wrote:

Would using one channel to power three speakers not reduce the amount of power each speaker gets meaning you lose overall volume and/or quality from each speaker? IE: if you split a 45w (the power my Android headunit claims to output per channel, unsure if that's peak or RMS) channel to three speakers wouldn't you then only have 3x 15w speakers? This is the assumption I made that led me to wanting power to each of the speakers.

No, because you are spreading the power between the speakers so the amount of air they can shift will actually be greater than having one speaker, giving more volume not less. The output of the amp is the full range of frequencies but the largest speaker can't move fast enough to reproduce the higher frequencies so they get lost. Equally the tweeter only has a 1" cone so works beautifully with the high frequencies but can't cope with the bass. The midrange then deals with the bits in between. Now you can just rely on the fact that the speakers won't respond to frequencies they can't really handle but it can muddy the sound as they will still try to, so the high frequencies will damp the cone in the bass speaker. This is where a crossover comes in. It is a set of filters so you feed it with the full range and it splits it into the three ranges, bass, mid and high which are then fed to the individual speakers. The non DSP mid line system (fed directly from the head unit) uses capacitors in series with the midrange and tweeters to block the bass frequencies while the high line system with the separate door amps uses a single amp but with a built in crossover so the bass is fed to the bass speaker and the rest is fed to the midrange and tweeter with a capacitor in series with the tweeter to keep the lower frequencies out. So what you have is 4 amps, one for each channel (FL, FR, RL and RR) with inbuilt filters to split the output between the different speakers.

The DSP system does much the same only it is controlled by a data line (so while it is only fed with a 2 channel stereo input, the data tells it how much to send to the front and how much to send to the rear) and can also alter the sound to give different effects by putting minute delays in outputs to make the soundstage move and add preset equaliser settings.

For the sub you just have one further amp, sometimes mono to drive a single speaker, other times stereo to drive a pair (or a stereo input that is then combined to drive one speaker). Looking at example 2.2 that Clive linked to, they are using the original head unit, passing it through an attenuator, which may also convert between balanced and unbalanced signals. Unbalanced means one leg is grounded, so a 1V peak to peak signal would be between 0V and 1V, whereas the same 1V balanced signal would vary between -0.5V and +0.5V. From that they then feed a 6 way amp, almost certainly incorporating filters, to drive the 4 main channels and a stereo sub. Virtually identical to what Marty's 4 door amps substitute for the DSP amp solution does only it doesn't include the sub amp as that was separate in the first place. It'll work fine as a substitute for a dead DSP amp and retaining the original head unit but when you start feeding it with signals it wasn't intended to be fed with, then you are in uncharted territory.

I suspect the reason for your whine, although not the pops and crackles which as you say are down to your soldering skills, is because the outputs from your Android unit are unbalanced but the amps are expecting to see a balanced input. Careful experimentation with grounding is needed to sort that and possibly also some filtering on the supplies (I've got a few boxes of FX1588 ferrite cores if anyone can use them or even knows what they are...).

However, Chris still hasn't popped up and told us what he is trying to achieve......

Sorry for this, I feel like I'm still not fully understanding.

It sounds like you're saying that there's no downside to splitting one un-amped channel (not counting the amp internal to the head unit) to 3 speakers and that there's no need for an amp to increase the power since with 3 speakers there's more air being moved.

If this is the case, why does anyone ever use an amp at all and not just run as many speakers as they can from a single channel?

I suppose I'm equating the wattage of the channel to the horsepower/torque of an engine, speakers themselves to the weight of the car and the amp to something like a turbocharger.

With a car you can increase the payload by hooking up a trailer. Without increasing the power of the engine you lose performance and the car gets slower and/or you have to work the engine harder to maintain performance.

If you add a speaker to an un-amped channel you must lose some type of performance, right?

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It depends what you mean by un-amped as there already is an amp in the head unit. In your case, it is rated at 4x45W, so that is the 4 channels each with a 45W amp to drive the speakers. An amp will be rated at an output figure into a specific impedance load, so you will see something like 45W into 4 Ohms, but it could equally be rated at 60W or 80W into 2 Ohms (and some are to make them sound more powerful than they really are) so as soon as you add additional speakers you are reducing the impedance and hence the amount of power it can supply (until you are down to a virtual short circuit and it either burns out or shuts off to protect itself). So yes, there is a point where adding more speakers won't increase the amount of sound as there isn't enough power to share between them but you are very unlikely to reach that point unless you get really silly and install speakers everywhere. Hence the need for huge 10,000W+ amps to drive the large amount of speakers at a concert, you've got to have enough speakers to be able to shift enough air to make the sound audible (at eardrum splitting volume) over a large area.

I've no idea what the output of the DSP amp is, or the door amps for that matter, but I suspect they will also be rated at something like 50W per channel (or in the case of the door amps, per amp). That would allow a manufacturer to say that it has a 250W audio system if you add the sub amp in too. The L405 can be had with a 1500W audio system but you have to bear in mind that once up to around 60% of the rated output, you start to get distortion so to keep the sound quality good you need an amp that is only ticking over at normal volume levels.

Unfortunately, the ICE and Hi-Fi world is full of bullsh*t.