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My 2018 GT audio build- JL Audio/Hertz

MrTej

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I got the audio bug after reading threads in this forum and missing a good sounding stereo system. I decided to re-live my youth and tear my 2018 GT with the Shaker 12-speaker system apart and put it back together again with all new stuff .

I researched for about a month and then took a week off of work and spent the entire time in the garage, cutting fingers, losing skin on sheet metal, getting burned by solder, contorting my body into positions it’s not designed to be in anymore, etc., etc., but I’m happy with the results.

I decided to go with a 3-way active system and replaced all front speakers with Hertz Mille Pros. I eliminated the center channel and rear speakers. JL Audio Stealthbox in the trunk. Powering the system are a JL Audio RD900/5 driving the front drivers, mid ranges, and sub, and an RD400/4 driving the tweeters.

I went with the Rockford Fosgate DSR-1 for processing, along with the iDatalink Maestro harness for wiring simplicity. I have a lot to learn with programming it, but the good news is I don’t have any kind of interference or unwanted noise coming through the speakers currently.

I did all the other typical stuff people are doing- FORScan, sound deadening, lots of zip ties and Tessa tape, etc. I can share more details if anyone wants.

Here are some pictures. Hopefully this will help others with some additional ideas for your builds.

Bottom layer of amp rack:
2679D358-6A34-42DD-90BB-A179FCBE0EBA.jpeg


I added a false floor that slides back so I can access the ground wire location In the factory bracket:
70679181-940E-455A-A903-BED06D76030E.jpeg


5C42946D-3B5C-4F8A-A025-47A3C0D42262.jpeg


I used the other hole in the bracket to secure the amp rack to the floor (note the fender washer in the middle):
931580D8-6DDF-475E-9A9A-CB8C0051F6A3.jpeg


Finished amp rack. All wiring is Tessa taped and aligned with the grooves in the spare tire well:
AECCBF20-9123-452B-ADC1-ACCA1EF7D0AD.jpeg


All that work just to hide it!
1C87887A-2A2F-4A89-80C0-5D23ADF2BF10.jpeg


I mounted the DSR-1 to the factory amp mount, and zip tied the RCA harness to minimize stress on the wires:
3C94F836-6FB9-4B8D-A135-8ADCF525645C.jpeg


The usb adaptor is just long enough to connect to the laptop when mounted in the factory location, or I can remove the 3 mounting bolts (2 bottom ones are 10mm and top one is 8mm) and pull it down. I tried using a usb extension cable With the DSR adaptor but it did not work.

I mounted my JL remote bass knob in the center console, replacing the 12-volt outlet in there. I used two 1 1/2 inch fender washers. On the back side , I used a utility knife to cut a slit wide enough to hold the washer in place:
57F8F5F6-858E-4CC7-AA7F-F42E62AB6D85.jpeg


I used black plasti-dip spray on the front washer along with the RBC mounting hardware to give it a finished look:
80420FC6-E0A9-459D-A25B-FEFDC31D31B3.jpeg


Mounted in the center console:
7E2B43D8-2B40-4175-A3DC-F0167E330301.jpeg


I still have to learn about and perform all of the DSP tuning and setting amp gains.

Special thanks to @StangTime, @thill444, @hobbie1, and @5.0_SD for your inspiration and help with all my questions. It has been much appreciated!
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thill444

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Such a clean install and, more importantly, you are happy with the outcome and learned a lot.

Congrats!
 

FatPat

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Wow, great job on the install! Looks super clean, and I'm guessing it sounds great.
 

StangTime

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Awesome job! Thanks for the honorable mention too. You got it finished before I completed my system! Haha!
I'm at the soundproofing stage in the trunk. Thinking I should take a day or two off work to get this thing wrapped up.
I love the sliding plate that holds down the amp rack. Very cool idea. I have been scratching my head on how I could use that bracket for grounding and to hold down the rack.
Did you do anything special under the rack to level it with the contours of the floor? Some spacers?

Your install looks great. Have you thought about covering the visible Killmat around the edges with some left over carpet?
 

ahl395

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Awesome and clean setup!
 

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MrTej

MrTej

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Awesome job! Thanks for the honorable mention too. You got it finished before I completed my system! Haha!
I'm at the soundproofing stage in the trunk. Thinking I should take a day or two off work to get this thing wrapped up.
I love the sliding plate that holds down the amp rack. Very cool idea. I have been scratching my head on how I could use that bracket for grounding and to hold down the rack.
Did you do anything special under the rack to level it with the contours of the floor? Some spacers?

Your install looks great. Have you thought about covering the visible Killmat around the edges with some left over carpet?
Thanks! Yeah I though I would be done in a few days and then my wife and I were thinking of heading off to Gatlinburg, TN for some awesome driving (tail of the dragon!). We ended up deciding not to go, and it’s a good thing because I had 7 or 8 solid sun up to sun down days working on it!

I did not need to do anything special to level it with the floor, other than move it around a little to position it. I actually bought a sheet of 2” thick foam from Joanne fabrics, thinking I would need it for exactly that reason, but I ended up not needing to add any.

I did think about covering the surrounding areas where the Kilmat is visible with leftover carpet, and I may just do that.

My challenge now is figuring out what steps to take and in what order to properly tune everything. From what I can tell, I need to set crossover points, set amp gains, and tune each channel separately in the dsp. I assume I should leave the crossover points on the amps alone and set them in the dsp. I just don’t know what order those steps should be taken in.
 

Cathul

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Set crossovers and levels first.
With the crossover err on the safe side. 80-400Hz on midbass, 400-3000Hz on midrange and tweeter 3000Hz and above.
Do basic time alignment for the drivers first. The DSR1 can help you with that as you can just put in the measured distances to each front driver (tweeters left/right, midranges, midbasses and sub) into the DSR1 and it will do the math for you.
This should give you a lot better sound than before even without eqing.
Leveling the drivers can be a bit harder without a microphone and an RTA, but it can be done.
 

StangTime

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My challenge now is figuring out what steps to take and in what order to properly tune everything. From what I can tell, I need to set crossover points, set amp gains, and tune each channel separately in the dsp. I assume I should leave the crossover points on the amps alone and set them in the dsp. I just don’t know what order those steps should be taken in.
Here's some help on tuning:

Using an RTA:

Read this thread (post#4) https://www.mustang6g.com/forums/threads/stereo-upgrades.143227/ where I discuss on how to get an RTA (real-time analyser) for cheap if you have a laptop.

Also have a look at the spec sheets for your Hertz drivers. The 3-way system identifies the passive crossover points in the manual. So I would start with those points for your active system.

Use a subsonic filter if you can so anything below 20hz is cut off. This wastes amplifier power and can damage subwoofers.
Use 12db/octave for all active crossovers
20hz to 80hz for sub
80hz to 450hz for midbass
450hz to 5.5khz for midrange
5.5khz and up for tweeter
 

Cathul

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Use a subsonic filter if you can so anything below 20hz is cut off. This wastes amplifier power and can damage subwoofers.
Use 12db/octave for all active crossovers
20hz to 80hz for sub
80hz to 450hz for midbass
450hz to 5.5khz for midrange
5.5khz and up for tweeter
Is the subwoofer a sealed box? If yes, there's almost no need for a subsonic filter.
And better use 24db slopes on the crossovers. Makes crossover phase a non-issue compared to 12db slopes where you have to flip phase for every other driver.
 
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MrTej

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Got the crossover points and time alignment set today. I found that somehow the sub controls on the DSR-1 are not controlling the sub. Anyone experiencing that?

Mic came in the mail today, so going to try the eq tuning tomorrow.
 

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StangTime

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Got the crossover points and time alignment set today. I found that somehow the sub controls on the DSR-1 are not controlling the sub. Anyone experiencing that?

Mic came in the mail today, so going to try the eq tuning tomorrow.
I don't have a DSR-1 but do you have the latest firmware installed?
 
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MrTej

MrTej

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I've been planing around with it this morning and what I found is channels 7 and 8 coming out of the DSR-1 are not being used to create the sub signal. My JL Audio amp has a switch for 2/4/6 channel. When I switch it to 6 (to use the dedicated sub input), the output from the sub goes away. I switch the amp back to 4 channel and the sub output comes back. So it seems that the sub output is being created from channels 1-4. I can even disconnect the RCAs going into channels 5 and 6 and I still have output on the sub. So basically right now, I don't have control of the sub through the DSR-1.

Another thing that I noticed is when I switch the amp to use all 6 channels, the sub output goes away, but I can hear very faint sound from the sub, and if I turn the gain up and use the controls on the DSR-1 to mute the sub channels, I hear the faint sound from the sub disappear. So it seems the sub signal from the DSR-1 is there; I'm just not getting the output.
 

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I've been planing around with it this morning and what I found is channels 7 and 8 coming out of the DSR-1 are not being used to create the sub signal. My JL Audio amp has a switch for 2/4/6 channel. When I switch it to 6 (to use the dedicated sub input), the output from the sub goes away. I switch the amp back to 4 channel and the sub output comes back. So it seems that the sub output is being created from channels 1-4. I can even disconnect the RCAs going into channels 5 and 6 and I still have output on the sub. So basically right now, I don't have control of the sub through the DSR-1.

Another thing that I noticed is when I switch the amp to use all 6 channels, the sub output goes away, but I can hear very faint sound from the sub, and if I turn the gain up and use the controls on the DSR-1 to mute the sub channels, I hear the faint sound from the sub disappear. So it seems the sub signal from the DSR-1 is there; I'm just not getting the output.
Is the DSR-1 set up as follows?:
upload_2020-7-19_19-23-44.jpeg


Are the channels set up as follows?:

Inputs: Fronts + Rears (Analog)
Outputs: Fronts (3-Way) + Sub
 
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MrTej

MrTej

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Is the DSR-1 set up as follows?:
upload_2020-7-19_19-23-44.jpeg


Are the channels set up as follows?:

Inputs: Fronts + Rears (Analog)
Outputs: Fronts (3-Way) + Sub
Yes they are.

2A2139F0-09A3-4961-B123-39797049ED6C.jpeg
F5744D90-F56D-439A-8513-FC7A40867878.jpeg
3A50235B-B2EF-425E-9239-4FF5051F54D5.jpeg
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