Anyone got audio out from M.O.S.T. ?

TakayasuKenduma · Sep 30, 2013

If I did not get it wrong, the XC60 has a M.O.S.T optical ring for the bus connections of the multimedia devices. As I would like to add an external amplifier, I was wondering if anyone was able to connect a DSP with MOST input and get analog audio out. From a brief search on the Web, I have been surprised in finding that MOST DSPs are not very popular, while I thought it would be a clean install for an audio upgrade for contemporary cars.
I was also wondering if the audio out of the stock High Performance Audio Multimedia has a sort of equalization to compensate the speakers (and the car environment itself) or it is totally linear, obviously with the equalizer and tone in flat. This is important to know, because when I will change the door speakers, if there is a preset equalization for the stock ones, it will probably not fit the replacements.
If I cannot get line out from MOST I therefore need to know if it will be enough to enter in the new amp with the speaker out of the stock amplifier (attenuated through resistors) or I need a DSP with an A/D converter to flatten (or eventually custom equalize for the new setup) before going to the new amplifier.

mark-sf · Oct 2, 2013

I would be surprised if you could get a digital interface working without the car complaining as it is a closed loop system with the amp having an input and output. You didn't mention whether you had Sensus or not as the audio system changed completely with the 2011.5 model. I don't have the HP system so I don't know about whether there is bass filtering. It is easy enough to check with an AC meter or scope and a frequency sweep program or mp3.

In the Premium System I have, I did not measure this type of non linearity though it does have an EQ curve associated with Dolby Surround. Had my sub addition not crossed over as well as it did with the built-in EQ, I would have gone the route of DSP driven from amp outputs.

TakayasuKenduma · Oct 4, 2013

Hi have an XC60 MY14 (unfortunately it arrived without the sensus connect). My goal is to understand what I can get as the cleanest signal from the audio system, in order to define what expense is worth for an upgrade of speakers and amplifiers. Now coming back to what I asked:

MOST . I have seen that there are devices such as the moBridge and the Audison da1 that interface with the optical bus and get the pcm out of MOST: unfortunately nobody does it for Volvo but it can be done.
A crazy crazy idea could be modifying the stock amplifier to get the analog line-out signal before the powerpack amplification or even a spdif compatible digital stream, if the circuits of the receiver of a most signal and the d/a conversion are in separate chips. Actually I am trying another solution with the iPod or android simulating iPod to have the playlist control on the dask through the sensus but the spdif out from the player directly, bypassing the MOST ring and the stock amp.

Equalization: where can I measure a signal? Is there any easily accessible location for connecting a probe to an audio output? Because this test is about feasibility, I would like to avoid to disassemble half of the car just for measurements.

Subwoofer: you said you used the equalization to realize the high pass for the door speakers. But what about the signal for the sub? where did you get the non-attenuated low range frequencies signal?

Thank you for your answers Mark. I see from your sub project of the sub and the rest of your answers that you are really an audio enthusiast!

mark-sf · Oct 5, 2013

TakayasuKenduma said:
Hi have an XC60 MY14 (unfortunately it arrived without the sensus connect). My goal is to understand what I can get as the cleanest signal from the audio system, in order to define what expense is worth for an upgrade of speakers and amplifiers. Now coming back to what I asked:

MOST . I have seen that there are devices such as the moBridge and the Audison da1 that interface with the optical bus and get the pcm out of MOST: unfortunately nobody does it for Volvo but it can be done.
A crazy crazy idea could be modifying the stock amplifier to get the analog line-out signal before the powerpack amplification or even a spdif compatible digital stream, if the circuits of the receiver of a most signal and the d/a conversion are in separate chips. Actually I am trying another solution with the iPod or android simulating iPod to have the playlist control on the dask through the sensus but the spdif out from the player directly, bypassing the MOST ring and the stock amp.

Equalization: where can I measure a signal? Is there any easily accessible location for connecting a probe to an audio output? Because this test is about feasibility, I would like to avoid to disassemble half of the car just for measurements.

Subwoofer: you said you used the equalization to realize the high pass for the door speakers. But what about the signal for the sub? where did you get the non-attenuated low range frequencies signal?

Thank you for your answers Mark. I see from your sub project of the sub and the rest of your answers that you are really an audio enthusiast!

I too am unaware of any MOST bridge device that works with current Volvos. It is true that with enough skill and knowledge there may be a way to get to a a post d/a analog signal. I do not know the design of the HP amp. If it is a Class D design then that may not be possible. Even if there was access one would likely have to provide a buffer circuit for impedance conversion to drive the outputs.

The HP amp should be under the passenger seat in the same position as the PS amp only smaller. There will be a molex connector facing rear that you can attach a meter to after moving the seat forward.

As to my sub crossover, I tapped into the PS Amp output and restored the low frequencies through a combination of the sub amp's gain and crossover adjustments. If I had not been able to get a satisfactory blend I would have resorted to a DSP interface to the sub, but I didn't need it because of the steep roll off due to my bandpass design and the crossover slope.

zerimar · Oct 7, 2013

I too am looking for a simple and cheaper way of adding a sub since I don't have the time to DIY and secondly I change cars after 3-5 years. I was looking at the possibility of adding an active sub from either Pioneer, Alpine, etc. One option I saw that is quite plug-and-play is from i-sotec http://www.i-sotec.com/soundloesungen/volvo/xc-60-2008-2010

@Takayasu: where are you based? Check out the last post from this V70 thread of a German forum http://www.motor-talk.de/forum/subwoofer-fuer-v70-iii-t3231741.html?page=1

@mark-sf: great job on your subwoofer project, I envy you man.

TakayasuKenduma · Oct 7, 2013

Grüezi zerimar, I am from Zurich.
i-sotec looks interesting if they have the right cables, i have no idea of the electronicsbut for a sub i think it is ok. Obviously nothing is MOST, they just take the amplified sound. I don't know if what they say about the V70 is applicable to the XC60, in any case nobody arrives with a cheap solution very convincing, no?

mark-sf · Oct 8, 2013

zerimar said:
I too am looking for a simple and cheaper way of adding a sub since I don't have the time to DIY and secondly I change cars after 3-5 years. I was looking at the possibility of adding an active sub from either Pioneer, Alpine, etc. One option I saw that is quite plug-and-play is from i-sotec http://www.i-sotec.com/soundloesungen/volvo/xc-60-2008-2010

@Takayasu: where are you based? Check out the last post from this V70 thread of a German forum http://www.motor-talk.de/forum/subwoofer-fuer-v70-iii-t3231741.html?page=1

@mark-sf: great job on your subwoofer project, I envy you man.

This amp integration looks very similar to what I did using the Parrot harness as the pictured connectors are those you would use to connect to the power amp's outputs. One concern I would have however, is that it appears they are getting the power for their amp that way as well. While it is true that the stock amp will draw less current driving the new amp, it is not clear that the existing wiring and ground are sufficient.

On the other hand the Pioneer Active sub TS-WX77A looks interesting as a drop in package solution with minimum DIY if you could still find one.

Thanks for the kind words.

zerimar · Oct 8, 2013

Your most welcome Mark. I also like doing DIY but currently don't have much time. Secondly, it's been ages that I've been doing electronics in detail and never did for cars.

Gruezi Takayasu. I lived in Rümlang for 10 years then had to move to the Rheintal region and have been living here for 12 years.

The high end i-sotec looks good but still too much money while the lower end seems to be reasonably priced but in both cases the actual sub is an added cost. The TS-WX77A is still available here for around SFr/USD 400.00. What about the TS-WX610A which is about USD 100.00 cheaper? How much work is involved in installing one of these? Which cable harness would be required?

Btw, I just saw 2 unconnected cables just under the rear seat. One looks like an optical cable. I took some photos with my phone but were not clear since our underground garage is too dark. I'll take proper photos soonest I can.

I don't listen to music too loud, that the other reason why I don't want to spend too much. Although the current HP system is not that bad, it lucks a bit of punch. Both of you are experts in this matter. Would any of you be willing helping me out if and when I decide to add a sub?

mark-sf · Oct 9, 2013

zerimar said:
Your most welcome Mark. I also like doing DIY but currently don't have much time. Secondly, it's been ages that I've been doing electronics in detail and never did for cars.

Gruezi Takayasu. I lived in Rümlang for 10 years then had to move to the Rheintal region and have been living here for 12 years.

The high end i-sotec looks good but still too much money while the lower end seems to be reasonably priced but in both cases the actual sub is an added cost. The TS-WX77A is still available here for around SFr/USD 400.00. What about the TS-WX610A which is about USD 100.00 cheaper? How much work is involved in installing one of these? Which cable harness would be required?

Btw, I just saw 2 unconnected cables just under the rear seat. One looks like an optical cable. I took some photos with my phone but were not clear since our underground garage is too dark. I'll take proper photos soonest I can.

I don't listen to music too loud, that the other reason why I don't want to spend too much. Although the current HP system is not that bad, it lucks a bit of punch. Both of you are experts in this matter. Would any of you be willing helping me out if and when I decide to add a sub?

I don't think Pioneer ever imported the TS-WX610A into the U.S. It would have been laughed at as a toy. 2x10cm likely in an IsoBaric design in a dinky enclosure is not a subwoofer regardless of what the claimed frequency response is. Note there are no levels or curves provided.

If you are not seeing a small black box bolted under the passenger seat with a green multi-pin connector as in the photos in my signature link, then it is possible that the amp is in the control unit. In the US both the High Performance and Premium systems have an amp under the seat with 3 connectors - Optical, Power, and Speakers/Accs. The green one in the picture is the later.

Not sure I can help much from this hemisphere (even though I am in Nuremburg for a conference next month, but feel free to fire away with questions.

TakayasuKenduma · Oct 11, 2013

Something like this could interest you:
http://www.car-audio.ch/Subwoofer/Aktivsubwoofer/?filter_fv_id[13][0]=&filter_fv_id[14][0]=126&value_conjunction[13]=1&value_conjunction[14]=1&filter_price_min=&filter_price_max=&Subwoofer=Aktivsubwoofer&cat=c36&cPath=35_36&page=2

the woofer is larger and there are more choices for the installation.

zerimar · Oct 14, 2013

Thanks guys for the inputs. I feel that the TS-WX77A is the most logical option in terms of specs and mounting option. It would fit nicely way down and still have enough power to push the bass through. Let's see, maybe it could be one of my Christmas gifts for myself.

krn · Oct 15, 2013

This company NAV-TV demo'd a MOST interface in an S60:

But it never appeared on their website. I found a reference on another website where
someone had it working in an S80. See post 10:

http://www.diymobileaudio.com/forum...um/system-design-help-me-choose-equipment-my-car/125831-volvo-s80-dynaudio.html

But not a lot of options out there.

TakayasuKenduma · Oct 15, 2013

I contacted NAV-TV in chat and the customer service told me that the product is not available. Briefly, my conclusion is that MOST to spdif just does not work for Volvo, maybe there are some exceptions like few BMWs or Mercs models but for the XC60 the path is different. I will see what is possible with DSPs connected to the amp output, and do some experiment with IPod (get digital out directly from an iPod controlled by the Sensus). BTW I have seen a Helix Match 8 channel amp with DSP extremely promising (not too expensive, configurable, small, less hungry of electrons than my Orion....)

krn · Oct 15, 2013

>> with DSPs connected to the amp output

That is what I did using a JBL MS8 on my 2011 S60.

Anyone got audio out from M.O.S.T. ?

TakayasuKenduma

mark-sf

TakayasuKenduma

mark-sf

zerimar

TakayasuKenduma

mark-sf

zerimar

mark-sf

TakayasuKenduma

zerimar

krn

TakayasuKenduma

krn

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