Hello,

I'd like to see these units' back side, and which ones do have 4 channel RCA outputs, so others with 997.2 SPP cars can understand all this. The 7870 unit which is the newest, shows output 3, mentions RCA Cable+4G-Sim Slot 20 Pin. So maybe it does have all 4 unamplified RCA channels?


It's been quite difficult to find out which units, and vendors have the 4 unamplified RCA outputs for 997.2 cars with Sound Package plus(not Bose, not regular wiring) in my case a GT3 with the original PCM 3.0.
Looking at the installation pics from all the vendors, I can't find an actual picture and concrete info on which versions would have the required 4 RCA outputs. I had been favoring the 7870 and QCM6125 ones, but it's still not possible to conclude which ones will feed my Oem ASK amplifier.

If anyone could please help, I'd appreciate it. I also am not able to see which are "public" and "private" versions, private seems to offer the 4 RCA outputs-

Thanks,
JB

 

Some AMLUC or CHSTEK mentioned the 4 RCAs in either the description, or in the Rennlist-made manual.
I U/L the files here if it can help others.
I found them here and there, I don't have theses units but I was interested in knowing the 4 RCAs possibilities as my APK 987.2 suffers from "ghost sound".
The PO installed a cheap HU and Volume can't go higher than 5-7 without being far too loud (even with all volume sub-menus at 0).
HTH

 

I have purchased several different Chinese android units to test with my external amplifiers. They all had very low voltage ( 1.2V) RCA outputs that clipped at max volume. I returned them all because of poor sound quality. I have yet to find an android unit that has 4V RCA outputs and is designed for the 997 except for the Mekede unit on Amazon.. The Mekede unit has good specs but I didn't like the shiny ***** and small screen. Keepin the faith someone will come up with a good unit for the 997 with 4V RCAs.

 

For all of my customers' cars, Porsche and otherwise, I never use the HU's line-level outputs, but use the speaker outputs with a quality adjustable line-level adapter. Zero issues when using a PAC SNI-35 or similar, and good clean 4v output. Has a nice side effect of eliminating any alternator whine caused by poor internal grounding (ie, not keeping power ground separate)

 

Hi @MattDevoCustoms Nice to learn new things every day !!

Am I right to understand that these High-to-Low units are inserted between the HU and the ASK amplifier to lower the level before entering the amplifier?
My 987.2 still suffers from "white noise" and volume must be kept between 4 and 7 maximum, even with HU settings at the lowest (as you advised me).

PAC SNI-35 are expensive in Europe, I believe one can find similar units.
There are some with 4-channels.

 

This is the wiring diagram for 997, not sure in for .1 or .2 cars(and if they're different):


What I'd like to see are actual pictures of the ASK inputs, and location.
Still difficult to find pictures, and more information. There seems to be less info on SPP cars than Bose ones-
JB

 

Thanks @JB911 for providing this schematic.
There are 9 speakers in my 987.2 ASK, too, so it gives me a better view, even if cooler coding probably differs in some ways.

Let's sleep on this (at least, me !!!).

 

On page 55, post #814, YarraMates posted his method of using the 4 line level outputs with RCA's to the Ask amp.
And he posted this picture of the Head unit, and said he purchased from Owtosin Official Store - Version 13 - 4G Qualcomm Snapdragon 665.

But looking at the picture of the back of the unit on his post, I see MTK8227 & RK Circuit Diagram at the top of the picture. But it's not not the picture of the back of the 4G Qualcomm Snapdragon 665(!):


And the RCA method he used:



And this picture, to depin or cut:


I found the Owtosin Official Store, looked for 4G Qualcomm Snapdragon 665, and selected Color:Qualcomm 6G 128G, "A Standard Versions with wire" $454.22:
https://www.aliexpress.us/item/32568...yAdapt=glo2usa


So if YarraMates reads this post and could please clarify if the 4G Qualcomm Snapdragon 665, and selected Color: Qualcomm 6G 128G I selected does indeed have the 4 line level un amplified outputs, I'd appreciate it.
This is a pic of the QCM 6125 on the vendor's site and you can clearly see it has a fan and I don't see 4 channels out:



Thanks again,
JB

 

Only a few HU have 4 RCAs outputs.
That's why the Hi-to-Lo units make sense for HU having only 2 RCAs (then not used) and connected to amplifier.
Newbie's opinion...

 

YarraMates and Vocan both have used this method, 4 RCAs to connect to their cars. Vocan's car is a 997.2 GT3 like mine.
Most discussions online elsewhere include the issue of if the unit is an FYT one or not, lots of hair pulling discussions favoring the newer version 7862S(compared to the older7862 models), and 7870 being the newest, as we approach 2026. Of course the goal is to get the newest one if it's gonna be living in the car for a few years.

The other preference for me would be for a QLED screen. I had found a vendor in which some models specifically indicated QLED, and only the Qualcom ones have it. But maybe IPS screens are fine and no cause for concern:

https://www.aliexpress.us/item/32568...origin_prod%3A

Selecting Color:Qualcomm 8GB 256GB, it says QLED, $372.61
But, as stated, none of the vendors show actual pictures of the unit, much less actual pictures of the back of units.

So for SPP owners, that's the difficulty in selecting which ones which would work. The option of "Public" and "private" units is also not disclosed as far as I can see.

The only way to see what YarraMate and Vocan ended up using would be for them to pull out their units and take pictures with specific info on the units purchased, but it's an irritating request to impose-

Thanks again,
JB

 

Hello all !!

Anyone has installed such a Low-to-High Converter in Europe ?
There are some "cheap" ones on Amaz....n, there is a Focal unit (HiLoV3) too at 4x the price.

And ... is it a good idea to use a 4-channels unit instead of 2x 2-channels ?

I have a Cayman 987.2 non-Bose with ASK.

Thanks for your advices.

 

all of these units support 4-channel RCA output (at least all of the FYT UIS-based ones), the resellers just don't include the proper harness. The rear outputs are on the same plug as the 2-wire CAN/serial interface from the box to the HU

I've used a 4-channel line-level converter without issue as well, it's just a matter of finding a decent quality one at a reasonable price. The cheaper ones do not get the job done.
I've recently switched to using the Recoil MALOC4 for 4-channel outputs and the PAC SNI-35 when I only need 2 channels.

 

Hi Matt,

Thanks for the reply. But the reason I'm skeptic about this is Vocan said on the GT3 thread that he had to return a HU, and get a "private" one with 4 Ch output. I was under the impression he said most HUs have 4 channel un amplified outputs.

I'll continue searching and comparing the available ones, and more detailed pictures would sure help-and the goal would be to get a newer one, since some of the models are about 5 years old now.

Best,
JB

 

personally, I wouldn't worry about the RCA outputs. IME, a good adjustable line-level converter gives a cleaner output.

as for the best unit, cost not a consideration, a UIS7870 based one is the way to go (unless there's something newer I haven't seen)

 

@JB 911

@MattDevoCustoms is right (as usual) about the line-level vs RCA's, as an OLD audiophile it took me some time to wrap my head around it but just google and you will see that is how car stereo guys are doing it now.

I have my Ali (Matt-special) HU driving my 10-channel active Audison system through the 4 line-level outs and it is awesome.