Database Info

How to increase subwoofer level only?

Hi guys,
I want to raise the volume level only for my subwoofer, but increasing the sub level in the equalizer results in a higher level for all speakers which sounds terrible.
I have the standard MTCD head unit and connected my active subwoofer to the corresponding ports. I also tried Malaysk ROM and updated MCU, but it remains the same.
Hopefully somebody can help

DieAbrissbirne said:
Hi guys,
I want to raise the volume level only for my subwoofer, but increasing the sub level in the equalizer results in a higher level for all speakers which sounds terrible.
I have the standard MTCD head unit and connected my active subwoofer to the corresponding ports. I also tried Malaysk ROM and updated MCU, but it remains the same.
Hopefully somebody can help
Click to expand...
Click to collapse
In amplifier app. All the way to the right.

I've found the sub level setting on the amplifier app panel does nothing for me. I change the settings on the amp unit itself. I did use the sub-out on the unit as using any other line-out from the unit resulted in poor audio.

DieAbrissbirne said:
Hi guys,
I want to raise the volume level only for my subwoofer, but increasing the sub level in the equalizer results in a higher level for all speakers which sounds terrible.
I have the standard MTCD head unit and connected my active subwoofer to the corresponding ports. I also tried Malaysk ROM and updated MCU, but it remains the same.
Hopefully somebody can help
Click to expand...
Click to collapse
ok, use the gain knob on the amp which drives the subwoofer impractical, but works...

stefcio007 said:
I've found the sub level setting on the amplifier app panel does nothing for me. I change the settings on the amp unit itself. I did use the sub-out on the unit as using any other line-out from the unit resulted in poor audio.
Click to expand...
Click to collapse
This is exactly my problem and the reason why I'm asking here.
Chaning the level in Equalizer App simply doesn't change anything.

DieAbrissbirne said:
Hi guys,
I want to raise the volume level only for my subwoofer, but increasing the sub level in the equalizer results in a higher level for all speakers which sounds terrible.
I have the standard MTCD head unit and connected my active subwoofer to the corresponding ports. I also tried Malaysk ROM and updated MCU, but it remains the same.
Hopefully somebody can help
Click to expand...
Click to collapse
DieAbrissbirne said:
This is exactly my problem and the reason why I'm asking here.
Chaning the level in Equalizer App simply doesn't change anything.
Click to expand...
Click to collapse
I know this won't be too helpful but I have no issues with this function on my PX5 unit, I installed a small sub the other day and I'm able to fully control the level using the far right slider on the EQ.
What might be of assistance is when I was installing the unit into my car, all of the break-out wires that plug into the back of the unit that give you your USB, Phono-in/Phono-out, SUB etc..... there are a couple of these that can be mixed up and potentially plugged into the wrong port.
I know, I did it......
I might be way off the mark but it's worth a look.

sirleeofroy said:
I know this won't be too helpful but I have no issues with this function on my PX5 unit, I installed a small sub the other day and I'm able to fully control the level using the far right slider on the EQ.
What might be of assistance is when I was installing the unit into my car, all of the break-out wires that plug into the back of the unit that give you your USB, Phono-in/Phono-out, SUB etc..... there are a couple of these that can be mixed up and potentially plugged into the wrong port.
I know, I did it......
I might be way off the mark but it's worth a look.
Click to expand...
Click to collapse
yeah u're right, but still...if the volume for all speakers change when moving only the sub slider, then there's something fishy there with the unit.
never heard of this effect, it either worked on the sub only or not.

zerozoneice said:
yeah u're right, but still...if the volume for all speakers change when moving only the sub slider, then there's something fishy there with the unit.
never heard of this effect, it either worked on the sub only or not.
Click to expand...
Click to collapse
Or probably the subwoofer is not plugged in to the right cable.

zerozoneice said:
yeah u're right, but still...if the volume for all speakers change when moving only the sub slider, then there's something fishy there with the unit.
never heard of this effect, it either worked on the sub only or not.
Click to expand...
Click to collapse
If the rear breakout connectors are plugged into the wrong port, we have no idea what effect that might have. It could be nothing, or it could be bridging something that sends a funky signal back into the unit.
It's worth eliminating this as a potential issue so that you can troubleshoot further.

Ok first. It should not be a problem if u change the settig for all speakers becouse.... Ur ampfiler has a high pass filter and low passt filter... So if u set more power on low it shold just come to the subwoofer if ur amp is setting right with the filter... The had unit send the low to all speakers but ur amp should just pass this to the subwoofer.
U need check.
1. Did u use chich connectors or just normal kabels
Booth are possible
2. Have ur amp right configuration with high pass low pass filter...
3. Is ur subwoofer right connected to the amp???
U can connect the sub to front or back chinch the sound is everytime the best if ur filter in the amp right configuration.... It dossent metter which port on head unit the signal comes from...

Maybe doing @7floor's sound mod would help ? It will certainly improve the sound quality.

Can i seperate the bass from my speakers and my sub?
When i lower the bass in my equalizer - my sub goes lower as well.
If i turn it up - my sub is fine, but my speakers go wild.
... i plugged it into the "sub" chinc cable... i have no dsp chip - any ideas?

EGOiST1991 said:
Can i seperate the bass from my speakers and my sub?
When i lower the bass in my equalizer - my sub goes lower as well.
If i turn it up - my sub is fine, but my speakers go wild.
... i plugged it into the "sub" chinc cable... i have no dsp chip - any ideas?
Click to expand...
Click to collapse
You need a HU that is able to set the crossover. It's on the hardware level. You need another HU or ROM.

jessevdh said:
You need a HU that is able to set the crossover. It's on the hardware level. You need another HU or ROM.
Click to expand...
Click to collapse
This is 2 years old - but thanks bud

[Solved] How to pass audio to premium (Bose) amp from PX5 MTCD HU (2013 Mazda CX-7/9)

Hello,
I am having trouble passing meaningful audio to a Bose factory amp from my PX5 MTCD (said amp comes with my 2013 Mazda CX-9 but I believe that the same hardware can be found in other contemporary Mazda vehicles). Instead of audio I only get a 2Hz very loud beep. The best guess (by me and the PAC guys) as to what happens is that the signal level is too high for the Bose preamp (which is known to have a low impedance) so that the amp is overloaded. I am feeding said amp directly from the preamp outputs of the unit. I believe (but I am not sure) that the way the unit is interfaced with the CAN bus is immaterial to the issue. Indeed, I connected the unit using the included CAN bus adapter as well as a PAC RP4-MZ11 adapter with the same result.
So my question is, is there a way to control the gain of the preamp outputs of such a unit? Do you guys have any other advice on what to try to fix this issue? Wild guesses are welcome (I am willing to experiment).
Thoughts are much appreciated. Many thanks!

In my Audi B7, which also uses a Bose amp like this, I used 2:1 step-down audio transformers along with a resistor divider network on the SPK out from the android headunit. I found the line out level to be too low to drive the transformers, and couldn't connect line out directly to amp due to non-isolated ground.

JAmBer99 said:
In my Audi B7, which also uses a Bose amp like this, I used 2:1 step-down audio transformers along with a resistor divider network on the SPK out from the android headunit.
Click to expand...
Click to collapse
Great tip, thank you very much. I will try it as soon as I can. Do you happen to remember the overall resistance and the ratio for the divider?
JAmBer99 said:
couldn't connect line out directly to amp due to non-isolated ground.
Click to expand...
Click to collapse
So that's what causes the trouble. Good to know, thank you again. Much appreciated.

For the record, it turned out that my issue was caused by the CAN bus adapter rather than audio source. Strangely enough, the adapter requires that the car be turned on (and that's a full on, not just ACC) for the first time. If this is not the case then max volume beeps are all the sound that is produced by the amp. As soon as the car is turned on once the amp/head unit combination will work thereafter on ACC as well as on ON.
This appears to be a "feature" of the vehicle rather than the adapter, as the same problem manifested itself with two totally different adapters (PAC RP4-MZ11 as well as the adapter that came with the head unit).
With this proviso the preamp outputs of the head unit drive the amp well, so that there was no need for a line converter in my installation. The preamp level is pretty high (so volume beyond 25% or so is unusable) but this can easily be fixed by playing with the gain on the head unit.

MTCD/E PX5 Audio Quality issues - Static/Noise/Interference

Hi all,
I have purchased a PX5 unit made for my 2008 Mazda 6. Unfortunately, it suffers from an issue with the audio quality. Whenever the audio level is above 0, a static/interference noise can be heard, and the pitch of this sound changes when driving, similar to alternator whine.
This is relatively loud, and can be heard even when moving or when sound is at low volume. If required, I could create a recording of the noise. I have updated the MCU to the latest available version to no avail.
I am relatively confident at soldering and am willing/able to take the HU apart to make modifications if anyone has any recomendations as to what I can do? I have seen various hardware mods floating around, but nothing that conclusively seems to say it will help with my issue.
There is also a large amount of static/interference when using Bluetooth for calls, but mainly to the party not connected to the car (IE the person calling in can hear the noise). Unsure if this is related, but the noise appears to be a similar pattern and pitch.
This issue is present both with the car running and off, and also was present on a bench power supply during testing.
Any help would be greatly appreciated!

Should be an easy fix. https://www.crutchfield.com/ISEO-rg...car/noise_suppressors_installation_guide.html
Sent from my Z981 using Tapatalk

Thanks for the post, but unfortunately the noise is present even when connected to a bench supply, with no additional interference from the car present. There is no amplifier in this scenario, so I am fairly confident the issue comes from the HU itself. I'm not sure if there may be something I can re-route or shield inside the unit to minimise it? I don't mind if I can't eliminate it entirely, but I would. Like to minimise the issue.
Thanks!

I found that I was able to remove one aspect of the noise by turning off the colour cycling of the front LEDs. This was causing a kind of pulsating low pitch siren type noise in the audio.
It appears that having the front LEDs on anything other than full power or completely off causes the noise to varying degrees.
I still have a fair amount of cracking/static type noises, but I was able to somewhat lower the volume and improve the quality by attaching RCA cables directly to the outputs of the BD37033 chip. I'm not entirely sure what occurs after this chip in terms of sound processing, as in was difficult to trace out on the PCB. Interestingly, this modification means that the static is produced even when the unit is booting or on mute, which didn't occur before. I found this odd, as the mute functionality (And all other functionality as far as I was able to tell) is retained.
I assume the signal goes back to the MCU before going out to the factory RCA outlets and amp.
If anyone knows more, I would lose to hear it!

I have the same issue: https://www.youtube.com/watch?v=gTNJVWFpBlw&feature=youtu.be
There is a static / hissing sound when the volume is on, changing volume doesn't affect it.
I might to try to upgrade the amp chip to Pioneer PA2030A from TDA7851 to see if it will fix it...

Hi.
I have the same issue with my radio in Mazda CX-9 with Bose.
Version of the radio:
PX5 Malaysk 6.0.1 MXC89L 20170901.180527 MCU VERSION MTCD_KLD_V_2.57_1 - now I have the newest version, and the problem is still the same.
I have a lot of noise when searching for something on the radio, or connecting something under USB (at the rear panel - when I'm connecting in the front - it is OK), while listening to music quietly.
What I've done so far:
1. Upgraded to the latest version of Malaysk with of course wipe all data - nothing changed.
2. Installed: anti-interference voltage filter, it works because I can not hear feedback from the car's electrical system, the alternator is not audible anymore.
3. I wrapped the cables on the back with aluminum foil plus tape insulation - nothing changed, maybe a little less noise from the radio, but still I hear all the time.
4. I connected back to the original radio - no noise - absolute silence from the speakers
The most annoying is the increasing noise of the car during driving, I have to manually adjust the volume, which does not change anyway.
Is "the cheap" radio from China, I dont know what to do.
I think that the problem is that the radio does not work well with the Bose amplifier.
I had Mazda CX-9 without Bose, and installed cheap amp with cheap radio from China - and everything worked perfect, no noises at all ! Because the amplifier was cutting out this noise with no problem.
Here the Bose amp have huge problems with that noise, I don't know why.
This noise is nothing but the noise of data transfer over the radio, which I hear all the time once more quietly and louder, as I connect, for example, a car camera to the rear USB, this noise is unbearable.
The best solution, IMHO is to remove the Bose amplifier from the car and connect the radio to another A / B class amplifier, which is much better at reducing these disturbances.
But it is a lot of work to make the whole installation work perfectly.

Me too...
I have also got this issue with my MTCD GS unit. My car has Bose also. I have tried earthing various point/things with the head unit hanging out of the dash but no change. I have also tried disabling the WiFi & Bluetooth and again no change.
I noticed the other day when I put my headlights on and the backlights on the unit came on the noise increased slightly so there might be something in the LED thing.
Andy

Exactly same thing for me too. Cheap units..

Hi.
I'll try with:
Car Stereo Audio Wire to 4 Channel RCA High to Low Audio Level Converter Adaptor
And let you know if it is OK.
I wonder, after all, the Chinese radio has a low output to the amplifier, just through the RCA plug, it can try this connection yet.
Connect to the Bose amplifier via the RCA plugs
PRODUCT FEATURES:
4 Channel Hi/Lo Audio level converter
Converts speaker level audio to line level (RCA) output
Adjustable output level to allow input to suit various amplifiers
Also eliminates signal noise
Maximum input from speaker level: 100 Watts

The noise is even related to the touch screen on my side, touching the screen changes the hiss

Removing the Bose amp and connecting a new amp with just RCA cables has improved the issue, but not eliminated it. My next step is to remove the amplifier chip entirely and see if that makes a difference (As I am only using the low level outputs I do not need the amp chip)

kaise123 said:
Removing the Bose amp and connecting a new amp with just RCA cables has improved the issue, but not eliminated it. My next step is to remove the amplifier chip entirely and see if that makes a difference (As I am only using the low level outputs I do not need the amp chip)
Click to expand...
Click to collapse
Have you tried connecting via normale speaker lines, using a HLA? -> I also have a factory amp and using the RCAs got me ground issues - not present with the normal lines, so I ordered a HLA.
You can lower the output to max -15db in factory settings which I use in the meantime..

Xorit said:
Have you tried connecting via normale speaker lines, using a HLA? -> I also have a factory amp and using the RCAs got me ground issues - not present with the normal lines, so I ordered a HLA.
You can lower the output to max -15db in factory settings which I use in the meantime..
Click to expand...
Click to collapse
Hi, thanks for the answer.
I reduced the decibels to -9dB and noticed that it is much better, but of course the noises are only less audible.
I'm waiting for High quality audio converter to RCA cables, and let you know and let if I have eliminated the noise completely.
DD

dranet said:
Hi, thanks for the answer.
I reduced the decibels to -9dB and noticed that it is much better, but of course the noises are only less audible.
I'm waiting for High quality audio converter to RCA cables, and let you know and let if I have eliminated the noise completely.
DD
Click to expand...
Click to collapse
Should recieve my HLA today and will report back aswell. I have given up on the RCA jacks from the HU though.

I found that the RCA jacks were considerably better than the speaker level outputs as far as both noise and quality go. I was already using the speker level outputs when I initially noticed the issue.

kaise123 said:
I found that the RCA jacks were considerably better than the speaker level outputs as far as both noise and quality go. I was already using the speker level outputs when I initially noticed the issue.
Click to expand...
Click to collapse
I agree. I was able to tune the the "static noise" out of my system using a 3-way electronic crossover/ line driver buy turning down its gain till the noise went away. Lost a bit of volume, but just had to turn the head unit volume up a bit more to make up for it. Not much you can do with speaker level inputs except not to use them and use external amplifiers for all your speakers.
I believe the cause of the noise is an internal isolation problem, not to sure if any isolation can be added to the inside of the unit, When the wifi was on i was getting some bad feedback as well, but i was able to tune that out as well.

Guys, I was able to install the HLA today and beside I cant bring it to clip the sound has improved regarding base.
Turned the gain little up and am now satisfied with the result.
I had a hissing noise from the start even with oem radio and this is gone aswell.
All that using the speaker lines towards oem amp.

Octane70 said:
I agree. I was able to tune the the "static noise" out of my system using a 3-way electronic crossover/ line driver buy turning down its gain till the noise went away. Lost a bit of volume, but just had to turn the head unit volume up a bit more to make up for it. Not much you can do with speaker level inputs except not to use them and use external amplifiers for all your speakers.
I believe the cause of the noise is an internal isolation problem, not to sure if any isolation can be added to the inside of the unit, When the wifi was on i was getting some bad feedback as well, but i was able to tune that out as well.
Click to expand...
Click to collapse
I also believe this is related to the inside of the unit having poor power delivery and bad isolation. Unfortunately the audio is all routed on the main PCB itself so it is not easy to isolate it. I did improve things considerably by soldering directly to the output from the BD37534FV controller and then using this as my RCA output. I did try some further digging but wasn't able to trace the source of the noise back any further.
Next I am going to try adding a capacitor to the power supply, removing the built in TDAXXX amp chip and seeing if I can improve the ground connection on the unit.

Hi.
Finally, I achieved what I wanted more or less, I reduced the number of noises to a minimum, using RCA converters from high to low voltage, adjustable at the expense of the output volume, but I made up for it with the Viper4android module, making listening to music comparable to sitting in a concert hall. Cool effects can be obtained with this module.
That's enough for me, of course, the noise is still present, but it's not as bothersome as before. I do not have the effect anymore that while driving from 100 km / h up, the noise increases and the volume stays constant.
Still, unfortunately, I can not connect anything to the rear USB, because the speakers start to tweet data transmission, similar to the transmission of the modem only faster, I have a USB webcam connected to the front of the radio, unfortunately it is annoying but at least there is no noise.
Of course, to reduce the number of noises in the car completely, I would have to exchange Chinese cheap radio, for which I paid some 300USD for some better, eg from Xtrons radio, they are supposedly better done, but I would have to play with 2DIN frames and it will not be anymore perfectly fit in place of the old radio.
Thanks
DD

This is what I use:
ESX High-To-Low Level Converter ISC4
or
HIFONICS HCV4

Enabling RCA Audio outputs?

Hello everyone
I tried to use the RCA Line-Level audio outputs of my Dasaita MTCD-PX5 unit to connect an external amplifier, but discovered that there's no signal coming out of them.
Do I need to enable them somewhere on the SW?
Thanks in advance
Max

Hi Max,
I am having the same issue, with Seicane PX30. I have temporarily spliced into the speaker wires since my amp can take high voltage input, however I have static/ clipping noise with high volume.
Please let me know if you figure this out!

SoakedCardinal said:
Hi Max,
I am having the same issue, with Seicane PX30. I have temporarily spliced into the speaker wires since my amp can take high voltage input, however I have static/ clipping noise with high volume.
Please let me know if you figure this out!
Click to expand...
Click to collapse
What did the reseller suggest.

currently in communication with support, sent them this:
I have purchased 2014 2015 2016 Subaru WRX Forester 9 inch Android 10.0 Head Unit.
There is no signal coming from the following RCA jacks:
• SUBWOOFER
• FL OUT
• FR OUT
• RL OUT
• RR OUT
They all register 0 volts using 40hz 0db test tone ¾ volume from bluetooth or auxiliary input.
Connecting AUX IN L/R to FL/FR OUT makes the cars 3.5mm aux jack work but there is still no output from the RCA jacks.
My unit has the DSP Sound System. I have seated the connector properly. All other functions are working normally.
How can I make it work?
Click to expand...
Click to collapse
they completely misunderstood my issue first go round . . will report back

SoakedCardinal said:
currently in communication with support, sent them this:
they completely misunderstood my issue first go round . . will report back
Click to expand...
Click to collapse
On my side, I never found a solution. Played around with several settings, but nothing...
Could this be a ROM issue?
Let me know if they ever reply back

marchnz said:
What did the reseller suggest.
Click to expand...
Click to collapse
maxiauer said:
On my side, I never found a solution. Played around with several settings, but nothing...
Could this be a ROM issue?
Let me know if they ever reply back
Click to expand...
Click to collapse
so . . they basically tried to bribe me $50 to stop bothering them.
I think I might be able to fix the crackliing by using my amp to sum the L + R speaker outputs instead of my homade y splitter from the stock speaker cables at the headunit . .

Sorry for the resurrection, but I just fixed this issue on my PX5 for anyone else running into this problem. TL;DR is that the harness does not have the RCA for Rear speaker outputs wired in but the PX5 DOES have the pins for it. The solution is to wire them into the harness.
SOLVED: Rear RCA Outputs for MTCE PX5
Edit: TL;DR The wiring harness does not have Rear RCA outputs (only front and subwoofer). I had to splice in the RCA for the rear because there are pins outputting signal. (See solution below for details) I'm running Hal9K Mod with Android 10...
forum.xda-developers.com

Hey guys!
I've just bought a PX5 Android head unit to Skoda Octavia 3, instead of MIB1 Bolero. Everything works fine, it's fast, but I have 2x2ch amps in car.
RCAs don't give any signal at all..... Nor rear or front, neither sub RCA-s. Wiring is perfect.
In Factory menu i could find a Power Amplifier Settings menu, but it's gray, can't be opened.
In the scroll down menu, no possibility to activate AMP.
Remote switches both amps, connecting a phone via 3,5mm jack to amplifiers, it works fine. When I connect back to the head unit, it stops working. I can only hear it working like 5% of the sound it should...
We measured if there is rupture with multimeter, we measured 0... no beep. Moreover we tried to measure the outcoming signal, but nothing. it's 0,00. On every RCA. Anyone any tips?

kukoladam said:
Hey guys!
I've just bought a PX5 Android head unit to Skoda Octavia 3, instead of MIB1 Bolero. Everything works fine, it's fast, but I have 2x2ch amps in car.
RCAs don't give any signal at all..... Nor rear or front, neither sub RCA-s. Wiring is perfect.
In Factory menu i could find a Power Amplifier Settings menu, but it's gray, can't be opened.
In the scroll down menu, no possibility to activate AMP.
Remote switches both amps, connecting a phone via 3,5mm jack to amplifiers, it works fine. When I connect back to the head unit, it stops working. I can only hear it working like 5% of the sound it should...
We measured if there is rupture with multimeter, we measured 0... no beep. Moreover we tried to measure the outcoming signal, but nothing. it's 0,00. On every RCA. Anyone any tips?
Click to expand...
Click to collapse
Send it back under warranty.

marchnz said:
Send it back under warranty.
Click to expand...
Click to collapse
The problem is, that is another week of waiting. I am in connection with the supplier, he asks the manufacturer about the problem. The way is good, since when I plug Front left to the Front left of the amplifier, I head very very weak sound from the front left speakers. But the outcoming signal is unmeasurable. In addition, in the Factory menu there is an option "Power Amplifier Settings", which is gray. Can't be reached..
Maybe somehow it is disabled in the menu, but I could not find in 3 hrs where.

kukoladam said:
Hey guys!
I've just bought a PX5 Android head unit to Skoda Octavia 3, instead of MIB1 Bolero. Everything works fine, it's fast, but I have 2x2ch amps in car.
RCAs don't give any signal at all..... Nor rear or front, neither sub RCA-s. Wiring is perfect.
In Factory menu i could find a Power Amplifier Settings menu, but it's gray, can't be opened.
In the scroll down menu, no possibility to activate AMP.
Remote switches both amps, connecting a phone via 3,5mm jack to amplifiers, it works fine. When I connect back to the head unit, it stops working. I can only hear it working like 5% of the sound it should...
We measured if there is rupture with multimeter, we measured 0... no beep. Moreover we tried to measure the outcoming signal, but nothing. it's 0,00. On every RCA. Anyone any tips?
Click to expand...
Click to collapse
As @marchnz .... send it back under warranty.
Every head unit I have ever had, there is no turn-on for the RCA's because they are already on. That includes my old px5 and new px6.... and I have been using RCA outs only for probably the last 40 years
What you could do is check the pins directly on the head unit plug to see if there is anything there. When you probe it with the multimeter try using a ground inside the machine instead of the ground on the plug.

Bob_Sanders said:
As @marchnz .... send it back under warranty.
Every head unit I have ever had, there is no turn-on for the RCA's because they are already on. That includes my old px5 and new px6.... and I have been using RCA outs only for probably the last 40 years
What you could do is check the pins directly on the head unit plug to see if there is anything there. When you probe it with the multimeter try using a ground inside the machine instead of the ground on the plug.
Click to expand...
Click to collapse
Optical toslink between audio equipment is highly preferred.
Even with a common grounding point for -all- connected equipment the chance of an unsnubbed high frequency feedback loop is real.
If so it will likely blow all your twitters and possibly the power amp in seconds*.
If the amp's big enough you'll see smoke and fire
At the very least use a common grounding point for all pieces of equipment. Use heavy gauge wire and keep the wire length as short as possible.
*A high frequency typically 40hz or higher feedback loop when fed into and/or through a power amp will result in a huge wattage output at that frequency. It will cause the speaker bypass to shunt all of it through your tweeters and effectively short out the power amp

You probably know much more about this than I do, but a few things don't make sense to me. You said high frequency feedback loop, but then referenced 40hz. Did you mean 40khz? 40hz is a pretty low frequency and I would think would be cut out by both integrated HPFs and amp level HPFs. I am very familiar with toslink as I use them between my PC and home audio amplifier, but I've never heard of them used between a head unit and amp. Every head unit and amp I've ever owned have used RCA outputs. I'm not saying the risk isn't there but why would both head unit and amp manufacturers not use them if RCA is so dangerous? It really is an honest question, so please don't take offense.

blackhawk said:
Optical toslink between audio equipment is highly preferred.
Click to expand...
Click to collapse
Well... toslink is preferred in high end equipment (bandwidth suffers in the cheap stuff).... and I would not describe these head units as "high end"
blackhawk said:
Even with a common grounding point for -all- connected equipment the chance of an unsnubbed high frequency feedback loop is real.
If so it will likely blow all your twitters and possibly the power amp in seconds*.
Click to expand...
Click to collapse
I think you misunderstand. I'm asking OP to look for a common ground FOR TESTING with his multimeter. If all the rca's are not working then there is a chance that something common (like the ground on the rca jacks) is broken.

objecttothis said:
You probably know much more about this than I do, but a few things don't make sense to me. You said high frequency feedback loop, but then referenced 40hz. Did you mean 40khz? 40hz is a pretty low frequency and I would think would be cut out by both integrated HPFs and amp level HPFs. I am very familiar with toslink as I use them between my PC and home audio amplifier, but I've never heard of them used between a head unit and amp. Every head unit and amp I've ever owned have used RCA outputs. I'm not saying the risk isn't there but why would both head unit and amp manufacturers not use them if RCA is so dangerous? It really is an honest question, so please don't take offense.
Click to expand...
Click to collapse
RCA's are mostly used on automotive head units. They have been around for decades. toslink is the new kid on the block and there are a lot of problems with it... frequency issues, sample matching issues, select few apps to use toslink with... yadda yadda. Personally speaking, I wouldn't use toslink instead of rca in a million years. Now it does have the advantage of less noise pickup on long runs of cable, but manucacturers like pioneer, alpine, kenwood... etc have combatted the noise issues with high voltage output from the rca's (pioneers are now 4 volts peak to peak on the rca's while android is still something like 1.4 volt PtoP). Then on the other hand with toslink you need HIGH QUALITY dac's to avoid sample and frequncy issues... and these android head units are NOT what I would describe as anywhere NEAR "high end"+
toslink.... not me thank you... not at this low price level anyway.
As for blowing tweets with stray "40hz" signals.... hasn't happened to me in 40 years of using rca's

Bob_Sanders said:
Well... toslink is preferred in high end equipment (bandwidth suffers in the cheap stuff).... and I would not describe these head units as "high end"
Click to expand...
Click to collapse
Just a friendly old school warning so peeps never learn what driver coils smell like...
Cheap stuff will likely have less design fedback safeguards than high end equipment.
Regardless of the amp's frequency response the fed back will be on the high end. 10khz would still behave like 60khz as far as the crossover is concerned.
Regardless its best to wire/ground it proper for best performance and minimal voltage drops... wire is cheap.
I have a friend that saw this happen on a high end system. All they heard was a static like noise and in less than a second the tweeters were smoking. A couple hundred down the drain. It can get real expensive fast and by the time you realize it's happening, it's already done.

Yeah, I don't think anyone sees these as high end in the audio production department. I think they have become somewhat popular because a lot of the main players in audio head units have been a little slow in the freedoms that Android provides in terms of apps, navigation, etc. They are too busy pushing their proprietary interface crap.

blackhawk said:
Just a friendly old school warning so peeps never learn what driver coils smell like...
Cheap stuff will likely have less design fedback safeguards than high end equipment.
Regardless of the amp's frequency response the fed back will be on the high end. 10khz would still behave like 60khz as far as the crossover is concerned.
Regardless its best to wire/ground it proper for best performance and minimal voltage drops... wire is cheap.
I have a friend that saw this happen on a high end system. All they heard was a static like noise and in less than a second the tweeters were smoking. A couple hundred down the drain. It can get real expensive fast and by the time you realize it's happening, it's already done.
Click to expand...
Click to collapse
You can blow a simple ic chip with static so we shouldn't use them? Freak things happen. That's life.

Bob_Sanders said:
You can blow a simple ic chip with static so we shouldn't use them? Freak things happen. That's life.
Click to expand...
Click to collapse
No that's ignorance and ineptitude.
I handled thousands of IC's and flat packs without damaging them by heat or ESD.
On a high end system with 7 mains blowing them out alone would be over $2G in replacement parts.
Anything worth doing is worth doing right.

objecttothis said:
Yeah, I don't think anyone sees these as high end in the audio production department. I think they have become somewhat popular because a lot of the main players in audio head units have been a little slow in the freedoms that Android provides in terms of apps, navigation, etc. They are too busy pushing their proprietary interface crap.
Click to expand...
Click to collapse
Well... as far as I know the higher end units are still going RCA..... and if there is ever a change I suspect toslink will be passed over in favor of the MUCH BETTER hdmi standard anyway.

Px6 Dasaita rca level outputs not working

After a few months of running a stock stereo system, I decided to spend 3.5k on a sound system and can not get any signal to come out of the rca outputs to the amp. Ive been scouring the net all week and all ive found is solutions to noise. I get 0 output from my rca's. Neither "Sub1 or Sub2" outputs work, and win i try and hook subwoofer up thru rear rca's, they dont work either. Anyone know the solution?

Redbeard1980 said:
After a few months of running a stock stereo system, I decided to spend 3.5k on a sound system and can not get any signal to come out of the rca outputs to the amp. Ive been scouring the net all week and all ive found is solutions to noise. I get 0 output from my rca's. Neither "Sub1 or Sub2" outputs work, and win i try and hook subwoofer up thru rear rca's, they dont work either. Anyone know the solution?
Click to expand...
Click to collapse
Is the unit an mtcd type

marchnz said:
Is the unit an mtcd type
Click to expand...
Click to collapse
Mtce I believe

The RCA's just work. There should be no adjustment needed to make them work. Are you SURE there is no sound coming from the rca's? Maybe you just don't have the amp turn-on wire connected (blue wire). It's a pretty common mistake.
If you are SURE there is no rca audio then the unit is defective.

There isn´t any configuration about RCA on the unit. I have the same one. Only you have the option to turn on or off the amp remote cable. But just that.

In the Amplifier app where you can sett your EQ etc you also have a tab where you can change levels for loudness etc. In there you also have the opportunity to turn the sub ON/OFF and set the gain level of the sub.