Installed new system and need assistance

[MarcelGous]

Good Day All

So i took my 2012 Audi Q7 to a reputable car audio installer here in my country, but was extremely disappointed when i left the shop.

Audio screen was replaced with a aftermarket android unit and a Hi-Low converter was added for signal to the amp (this was due them not getting signal from the Android unit)

So when they finally connected the sub there was no signal coming to the sub, they then found that the Converter was completely turned down, i asked the installer if they now set the converter to 2v based on a 40hz signal with the radio turned up 3/4 of they way?

They said no, they just turn it half way open . . . . . .i then asked them how do they set the amp? Where i got a response of they set the gain and everything by ear. . .


Basically I'm not happy with the bass I'm getting at all from the setup and wanted to check the tuning myself, however for some odd reason i get no voltage on my multimeter when connected to the speaker output on the amp. The bass sound hollow and there is now low end frequency bass that's expected

I cant run a 40hz frequency long seeing as i don't know where to disconnect my factory speakers so they don't get damaged while testing on the amp

Currently setup

• Android radio
• OEM speakers running from the Audi media drive
• Energy Audio Champ mono amp 720w RMS @ 2ohm
• PAC-LP7 converter
• Kicker 48trtp122 - 12" sub - 500w RMS @ 2ohm (Frequency range 25 -500hz)

I purchased a oscilloscope, but it will only arrive mid to end May so its an extremely long time still.

Current plan of action:

1) Test distortion from radio by tapping into the speaker wires in order to find highest volume with clean signal
2) Test the Loc converter to insure its set to a 2v output when receiving a consent 40hz signal from the radio (should this be done on 0db or -5db?)
3) Set gain on amplifier with oscilloscope while receiving a consent 40hz signal from the radio and LOC
4) Try and set the crossovers (sub sonic to about 25hz and LPF set to 90hz) this is if i find out how to actually do this with the dial only displaying max and min values
5) Keep Bass Boost to 0db and keep Phase shift on 0

My bass control knob will be set on full while i do the above seeing as i would like to turn the bass down if needed but i must never be able to turn it louder than the max set value to avoid clipping.

The one thing i don't know would be the frequency range of the speaker wire they tapped into for the LOC, i believe they must have tapped into the from door woofers so it would be a low end frequency right? would this change anything on how i set my LOC?


Any advice would be greatly appreciated

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[hispls 5,000+ posts]

What exact head unit do you have? That is often the place to start looking for trouble.

Setting gains by just listening to music is fine assuming your intention is listening to music, that is provided you know what you're doing. If your LOC was set by "Just turning it halfway up" this doesn't inspire a lot of confidence that the installers have their **** together.

I do not agree with trying to set gains via test tones and DMM unless your intention is to only play test tones and look at a DMM or scope output. If you're going to listen to music, set gains while listening to the sort of music you intend to play or if you're going to be doing competitions set gains via termlab numbers.

 

[1aespinoza 10+ year member]

The one thing i don't know would be the frequency range of the speaker wire they tapped into for the LOC, i believe they must have tapped into the from door woofers so it would be a low end frequency right? would this change anything on how i set my LOC?

Set it up just how you planned it. Those door speakers get a wide signal, so no special treatment us necessary.

set to 90hz) this is if i find out how to actually do this with the dial only displaying max and min values

If you play a 90hz tone, it will be the highest voltage when you get to it on the dial. The further you sweep away from it, the voltage will drop. I hope this makes sense.

Where i got a response of they set the gain and everything by ear. . .

I set my own gear by ear, but other people's gear, I just started setting it by multimeter less than a year ago. Have not had an issue in either.

I cant run a 40hz frequency long seeing as i don't know where to disconnect my factory speakers so they don't get damaged while testing on the amp

If you are going to play music that plays 40hz and below, your doors will play that as well. Best bet is to tune with them getting the full signal to prevent blowing them when that awesome track pops up. If that is not viable, you can install Bass Blockers on their positive terminal.
As for the current lack of bass. First check the polarity of the LOCs, then the polarity of the subs. Those installers seem sketchy to me.

 

[MarcelGous]

What exact head unit do you have? That is often the place to start looking for trouble.

Setting gains by just listening to music is fine assuming your intention is listening to music, that is provided you know what you're doing. If your LOC was set by "Just turning it halfway up" this doesn't inspire a lot of confidence that the installers have their **** together.

I do not agree with trying to set gains via test tones and DMM unless your intention is to only play test tones and look at a DMM or scope output. If you're going to listen to music, set gains while listening to the sort of music you intend to play or if you're going to be doing competitions set gains via termlab numbers.

The radio is an imported android radio that fits the Audi Q7 dash, however as far as i understand this unit just connected into the exciting system with a T harness. I can still connect to the original audi media center and i could not find any difference in the audio quality.

link for reference: https://www.aliexpress.com/item/1005003129233050.html?spm=a2g0o.order_list.0.0.10281802urLCbM

 

[MarcelGous]

Set it up just how you planned it. Those door speakers get a wide signal, so no special treatment us necessary.

If you play a 90hz tone, it will be the highest voltage when you get to it on the dial. The further you sweep away from it, the voltage will drop. I hope this makes sense.

I set my own gear by ear, but other people's gear, I just started setting it by multimeter less than a year ago. Have not had an issue in either.

If you are going to play music that plays 40hz and below, your doors will play that as well. Best bet is to tune with them getting the full signal to prevent blowing them when that awesome track pops up. If that is not viable, you can install Bass Blockers on their positive terminal.
As for the current lack of bass. First check the polarity of the LOCs, then the polarity of the subs. Those installers seem sketchy to me.

Thank you for the reply, i will definitely be checking the polarity of the LOC and Subs over the course of this weekend, the strange thing i cant understand is when i quickly played the radio on a high volume and tested the speaker terminals of the amp even on max gain i could not get over 5v where according to most videos i watch it should be set to about 37.94v (this is based on the square root of 720w rms @ 2ohm) This is unless I'm completely misunderstanding something

Really hope i can get this sounding better over the weekend

 

[hispls 5,000+ posts]

The radio is an imported android radio that fits the Audi Q7 dash, however as far as i understand this unit just connected into the exciting system with a T harness. I can still connect to the original audi media center and i could not find any difference in the audio quality.

link for reference: https://www.aliexpress.com/item/1005003129233050.html?spm=a2g0o.order_list.0.0.10281802urLCbM

The issue with trying to start with stock head units or unknown Chinese source is that you really do not know what sort of EQ, crossover, or other processing they're doing to their outputs. A clever manufacturer designing the factory sound system might be doing some sound processing to work around the limitations of factory speakers and you may be starting out with some non-linear signal.

First thing you'll want to do is to make sure you're getting a flat and full range signal into your LOC, but I can't think of an easy way to test this right off the top of my head.

Really the trick to any of this is to start at one end and work your way through testing everything along your signal path to try to figure out what is and isn't working properly by process of elimination.

 

[1aespinoza 10+ year member]

First thing you'll want to do is to make sure you're getting a flat and full range signal into your LOC, but I can't think of an easy way to test this right off the top of my head.

He stated that the installer could not get a signal from the RCA outputs, so they spliced into the front speakers into a passive LOC. If the speakers are playing full range, then the LOC should be putting out the full range as well. Maybe the LOC is bad even though it is new. Did not another user have this same issue not to long ago?

i could not get over 5v where according to most videos i watch it should be set to about 37.94v

Make sure you are on a/c volts. Try testing the amp by connecting your phone to it with an 3.5mm to RCA cable. Any electronics store should carry one.

 

[hispls 5,000+ posts]

If the speakers are playing full range, then the LOC should be putting out the full range as well.

That's your big "if" though. How do we know that the source he is tapping into is full range and not somehow altered/processed? If not high passed from the factory source unit where is it high passed? Is bass attenuated somehow below whatever frequency the manufacturer decided the stock speakers can't handle?

The worry always is that whoever designed these stock "premium" sound systems baked in some sort of crossover/eq right into the brains of the thing.

 

[MarcelGous]

Hi Guys

thank you very much for all the responses and advise so far.

I had a moment this morning to search for the PAC-LP7 converter and found it under the seat close to the battery, however seeing as i do not have the correct spline bit yet i cant remove the seat in order to see what they did with the cables, however i got hold of the converter and played a 40hz signal from the radio but when i placed my multimeter on the RC output i get no voltage at all on the multimeter

Side note the gain on PAC was also turned completely open so they ready did not know what they are doing

So I'm really stuck here, could it be that they tapped into a speaker line that has a HPF as @hispls mentioned?

Still need to test the sub with a 3.5mm jack to RCA cable as mentioned above

 

[MarcelGous]

okay so did the test now with my phone connected to the amp and and playing a 40hz tone i could reach up to 50v on the speaker output of the amp with my phone on full volume and the amp gain on full so i believe i would be able to easily set the gains correctly if i can just figure out the issue

i played a 1000hz tone as well but still no voltage picked up on the LOC

 

[1aespinoza 10+ year member]

i played a 1000hz tone as well but still no voltage picked up on the LOC

It is probably like hispls said, a highly modified signal, or a bad LOC. Did they connect to one speaker or left and right?

 

[MarcelGous]

I'm going to see if i cant pick up a set of those clips needed to remove the factory radio and then connect a RCA lead directly from the RCA output to the amp and hope I get lucky there.

Only concern would be that if I do connect the RCA leads, will the sound also still run to the speakers via the factory setup seeing as my amp is only running my sub.

@1aespinoza I could not yet reach the connection point of where they tapped into the factory speakers, but I can just image that they probably only connected to one speaker wire. . . . I'm hoping that all the speaker wires are run along one side seeing as if the RCA's don't work I would want to try and tap into all the speaker wire in the hopes of getting a full signal

 

[1aespinoza 10+ year member]

full signal

I just remembered why I have heard that hollow sound you asked about. It was when my RCA wires were pulled taut by a sliding box. They were partially pulled out to the point that the center pin was making contact, but not the outer sleeve. Stands to reason that if the speaker grounds are not connected, you will replicate the hollow sound.

 

[MarcelGous]

Someone mentioned this LOC can maybe sort out my issue, any opinions?

https://www.amazon.com/dp/B084HL1D7P/?tag=caraudiocom-20

 

[1aespinoza 10+ year member]

Someone mentioned this LOC can maybe sort out my issue, any opinions?

https://www.amazon.com/dp/B084HL1D7P/?tag=caraudiocom-20

Judging by the specifications, it should be perfect. Remember to first check the signal going into the LOC before purchasing anything.