Keeping Center Speaker Dolby With Aftermarket Hu


pcguru000

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The buttons and knobs on my stock hu in my c70 are looking (and acting) old... I figured it may be time for an update.

http://www.crutchfield.com/p_110VM9224/Jensen-VM9224.html?tp=5684&avf=N&nvpair=AG_Size|FFDouble%40DIN#details-tab

Not looking to spend a grand, just something on the lower end... want it to be full touch screen though.

I think the dolby processor was separate of the stock HU is that true? If the preamps for a after market HU are just wired into it (and the stock amp as well) will they all work as they do now?

Just don't wanna loose that center speaker sound, its awesome :)

Also my center speaker grille fell apart... the volvo plastic just crumbles... i can't seem to be careful enough :( any solutions other than junkyard? Are there after market speaker covers?

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That's a Volvo OEM cover that is fairly unusual - junkyard will be your only option to replace it. But I've not heard of anyone successfully retaining the center speaker with a non-OEM HU.

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Perhaps just hard wiring the left or right channel to the center speaker? Just a thought.

Ive seen the HU's that say 5.1 surround, is there now way to yank that for the center channel... Or would that only work with 5.1 encoded audio.. not the processing :/

Also maybe use the "front" or "rear" preamp rca outputs- wire them to a separate small amp just for the solo center speaker? Even if it was a mono mixed sound it would still give the center effect.

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If you want true surround, look for an HU with 5.1 surround.

You can use a basic "New HU with OEM Amp" wiring kit for most of the job:

http://www.ebay.com/...=item33645de8d5

That'll get you 12 VDC power to the new HU and sound at the 4

corners using the existing OEM amp. Pretty much plug and play.

( Don't forget to connect the power antenna or the radio won't play.)

Unless you find a new HU with an amplified center channel output,

you'll have to round up a little amp to drive the dash speaker.

Get one small enough to fit where the old OEM Dolby mounts and

it should be a pretty simple install. The stock dash amplifier power that

comes from the Dolby box is only 25 watts. The 12 volt power at the

radio connector should handle an small amp like that with no problem.

Since the center only runs mids and highs, not bass, it doesn't need much.

You can probably score a tiny stereo amp and bridge it into mono for that.

As for the grill? I'd check the dealer price or just find one at a J/Y.

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Keep us posted as to what you end up doing. This has been the main reason I've kept the stock HU and not upgraded

Yeah im really torn because of it LOL

My general idea (please correct me if im wrong) - is that the dolby processor takes a stereo left and right and generates a "nice" (not just mono but using dolby algorithms etc) center channel.

So

[stock HU] > [stereo] > [Dolby] > [Center Speaker]

Why can we not offer it [dolby] ANY Stereo source such as another HU... most new HU's have preamp outs.

Could we not just take the left and right preamps from a new hu - splice into them of course, and send them to the stock dobly processor, which inturn powers the center speaker (it does power the center speaker correct? Or does it simply produce a preamp thats then diverted BACK to the stock HU... (i can't imagine this is the case, just asking).

Next question is power, does the dolby get powered by the that 6 pin din? okay- easy so splice power to it... from a ignition linked power source- like the cig lighter or simply the radio...

Worst comes to worst you could also take the left positive and right negative leads for the front speakers and use those to power the center speaker, no dolby of course however still a unified center channel mono would be better than nothing...

Maybe I am over simplifying it- I haven't even taken my hu out yet... Does the dolby processor have some special input it requires from the stock HU that links it to that audio "mode" button? or is that simply a power on or off?

Been searching, any wiring diagrams, charts etc you guys have would be useful- id like to make this a real possiblity , Dolby + after market HU in these cars would be nice. especially since these HU's are dying now decade later...

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Yeah im really torn because of it LOL

Been searching, any wiring diagrams, charts etc you guys have would be useful- id like to make this a real possiblity , Dolby + after market HU in these cars would be nice. especially since these HU's are dying now decade later...

Wiring manual here on MVS is your friend. Start with pg 183. Your problem is that the center speaker connects directly into the HU through a special port.

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Wiring manual here on MVS is your friend. Start with pg 183. Your problem is that the center speaker connects directly into the HU through a special port.

Thanks for the wiring info! :)

As far as this "special" port- from the screen shots ive seen, it looks like just another 6pin din input- which as far as i know is just a connector- once you hack that off its just 6 (or maybe less) wires on the inside of the cable...

Ill take a look at it this weekend likely when i have some light. (damned winter)

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There are aftermarket Dolby 5.1 processors designed for in-car use, the problem is they're prohibitively expensive for most people.

Units such as the JBL MS8 and Alpine PXA-H800 can be had new for $550+

One nice thing is that both those units are compatible with a factory HU as well, so if you decide to sell your current car, you can still use it in whatever car you have next.

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ive looked into those, and similar setups - they are ridiculously priced... and as it is, we have the processor, just got to put it to use.

One thing i noticed, page tweleve of this doc- http://www.matthewsvolvosite.com/downloads/1999_S70_C70_wiring_diagram.pdf it makes it look like the center speaker is wired DIRECTLY to the HU- if that is the case that may make this more difficult, i will be pulling things apart this weekend and looking at it futher.

THanks for the the docs again!

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Perhaps just hard wiring the left or right channel to the center speaker? Just a thought.

Ive seen the HU's that say 5.1 surround, is there now way to yank that for the center channel... Or would that only work with 5.1 encoded audio.. not the processing :/

Also maybe use the "front" or "rear" preamp rca outputs- wire them to a separate small amp just for the solo center speaker? Even if it was a mono mixed sound it would still give the center effect.

Center "effect" or a center speaker that plays something?

Yeah im really torn because of it LOL

My general idea (please correct me if im wrong) - is that the dolby processor takes a stereo left and right and generates a "nice" (not just mono but using dolby algorithms etc) center channel.

So

[stock HU] > [stereo] > [Dolby] > [Center Speaker]

Why can we not offer it [dolby] ANY Stereo source such as another HU... most new HU's have preamp outs.

Could we not just take the left and right preamps from a new hu - splice into them of course, and send them to the stock dobly processor, which inturn powers the center speaker (it does power the center speaker correct? Or does it simply produce a preamp thats then diverted BACK to the stock HU... (i can't imagine this is the case, just asking).

Next question is power, does the dolby get powered by the that 6 pin din? okay- easy so splice power to it... from a ignition linked power source- like the cig lighter or simply the radio...

Worst comes to worst you could also take the left positive and right negative leads for the front speakers and use those to power the center speaker, no dolby of course however still a unified center channel mono would be better than nothing...

Maybe I am over simplifying it- I haven't even taken my hu out yet... Does the dolby processor have some special input it requires from the stock HU that links it to that audio "mode" button? or is that simply a power on or off?

Been searching, any wiring diagrams, charts etc you guys have would be useful- id like to make this a real possiblity , Dolby + after market HU in these cars would be nice. especially since these HU's are dying now decade later...

[stock HU] > [Dolby] > [stock HU] > [Center Speaker]

Center channel is wired directly to the 901/900, the DIN cable is more than 6 wires to support the center+ all corners of the vehicle. The Dolby processor is a hardware version of the newer digital units.

1. find a location for the stock HU and intercept the center inside, while still using it as the amplifier

2. pirate the center components from both the 901 + dolby and remake the center circuit

3. actually buy a nice new processor

many options,just pick a path

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[stock HU] > [Dolby] > [stock HU] > [Center Speaker]

I unplugged some wires while it was running this morning- i see this exactly as you stated now... i saw the speaker power/signal for the center, that was obvious and when unplugged the center signal stops.

And then i saw the big one (looks like a din cable but im thinking its not now) with the 6+ wires that support all corners etc... unplugged that (probably not a great plan but nothing broken) - dolby drops tottaly... so yes you are dead on.

I am going to look into this a bit more... - also you are right- theres a major difference between center sound and center effect... i used the wrong word.

Next thought would be to get wiring information for that big 6+ wires Dolby cable, anyone? :) If we knew what each of those wires did that may help, I am guessing there is signal for stereo for four corners (front l/r rear l/r) and then power and a ground (which actually makes perfect sense then, 6 wires.

If thats the case, I would imagine I could make a "dolby wire to rca" wire.

And if all else fails I guess $$$ new processor lol but if I can make something work with what i got :) why not... plus the dolby processor we have is actually really nice imo.

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Next thought would be to get wiring information for that big 6+ wires Dolby cable, anyone? :) If we knew what each of those wires did that may help, I am guessing there is signal for stereo for four corners (front l/r rear l/r) and then power and a ground (which actually makes perfect sense then, 6 wires.

If thats the case, I would imagine I could make a "dolby wire to rca" wire.

Virtually all the internal boards have labeled pin connections. Simply take your 901 apart to gain access. Same is most likely for the processor, though I have never taken one of those apart personally. Soldering male RCA ends to plug into your new radio makes the most sense. You will most likely need to either retain several of the 901 internal boards to keep the ability to activate Dolby selection, or make your own either with relays or a processor chip of your choice.

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Soooo tonight i scored one of these, http://riverparkinc.com/display.php?page=1&list=mfg&id=VNMC1000 - used from a local pawn shop/front :> (looks like a damn front lol... sketchy but tested the device there, worked fine...)

THis thing has more features and a VERY slick looking UI than even the sony xav models- AND has 5.1 output- a dedicated center chanel rca output !!!

He said he wanted it for his car but would sell for 300- i offered 250 and was out the door with it :) - its used, but not a blemish on it.

Will post back when i get it working. -Any recomendations as far as plastic for the mounting around it? Its going to look ugly w/o anything... (guessing its gona need a custom bracket too...

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