Amp Replacement & Sub Input Question (Predicament?)

[MRobster]

Need help as I am planning to install a new 5ch amp in my 2000 M Roadster. I have the HK system with two amps: the main one and a sub amp.

Here's my predicament.

My new Continental head unit does not have an RCA out for a sub. It plugs straight into the same adaptor used by the original CD43. Trouble is, the CD43 goes into the amp and the amp has a feed into the sub amp.

Well, both the amp and sub amp are going the way of the dodo to be replaced by my new 5ch amp.

As such, what do I use as a sub input into my new amp?

[MRobster]

Have done some research. I think I need this: https://www.amazon.com/SCOSCHE-LOC80...780761257&th=1

[z3forlife]

If you don’t have a separate sub output then the amp will have to separate the signal internally. Most new amps can do that but you also would need to install a sub level remote up in the cabin. My 1st install used the stock head unit and worked that way but I didn’t have a remote sub level adjustment. I had to set it at a acceptable level and leave it. My current head unit has a separate sub output so I can adjust sub level to the amp through the head.

[s8ilver]

I'd buy a signal summing amp. AudioControl is top of my list. If you already have the amp, a good powered LOC would be my path; that's how I added a sub to mine prior to upgrading the rest of the system.

Sent from my SM-G975F using Tapatalk

[MRobster]

Thanks. Did you use a line output converter in your first setup? I'm ok setting it and leaving it ... and I have adjustments on the amp itself for level and LPF.

If you don’t have a separate sub output then the amp will have to separate the signal internally. Most new amps can do that but you also would need to install a sub level remote up in the cabin. My 1st install used the stock head unit and worked that way but I didn’t have a remote sub level adjustment. I had to set it at a acceptable level and leave it. My current head unit has a separate sub output so I can adjust sub level to the amp through the head.

[z3forlife]

No. I used the stock head F/R channels and connected to the “speaker level” inputs on the amp. How are you connecting to the harness at the amp ?

[AJLM34A]

Get an Audio Control device that is made for factory integration (aka, speaker wire input) and let it process a full range signal to separate F/R/S outputs. I would say buy an Audio Control amp but most of those are high power/high current draw and overkill in a E36 Roadster.

[MRobster]

What did you use for inputs into your sub channel - or are you saying your amp didn't need a separate input to produce output? As for connecting to the harness, short answer is I don't know because I have not torn apart my trunk. I assumed I'd need to cut off the harness because there are no adaptors (based on forum research) and then I'd have input wires from the head unit with an RCA connector for each channel since that is how my amp input is designed.

Forgive any dumb questions. I have installed stereos and amps but they were simpler than what I'm doing here.

No. I used the stock head F/R channels and connected to the “speaker level” inputs on the amp. How are you connecting to the harness at the amp ?

[s8ilver]

Get an Audio Control device that is made for factory integration (aka, speaker wire input) and let it process a full range signal to separate F/R/S outputs. I would say buy an Audio Control amp but most of those are high power/high current draw and overkill in a E36 Roadster.

But, getting clear audio top down at highway speeds is pretty cool. I run the AudioControl LC-5.1300 and picked it up through Discount Bandit for about $570 (vs. Crutchfield's price of $899). Neat thing is that you can run it bridged and push 400W to each front woofer (that doesn't mean you need 400W woofers, but amp headroom is never a bad thing). I'm currently running it in 5 channel mode, and it's incredible with the hardtop on. I run a simple PAC LC-1 (~$10) to adjust sub gain, but AC sells their own sub control unit that plugs into their amps.

I couldn't find a better 5 channel amp for the price. In the past I'd say the Alpine stuff was pretty great, but no signal summing and doesn't make the power that AC does.

[s8ilver]

What did you use for inputs into your sub channel - or are you saying your amp didn't need a separate input to produce output? As for connecting to the harness, short answer is I don't know because I have not torn apart my trunk. I assumed I'd need to cut off the harness because there are no adaptors (based on forum research) and then I'd have input wires from the head unit with an RCA connector for each channel since that is how my amp input is designed.

Forgive any dumb questions. I have installed stereos and amps but they were simpler than what I'm doing here.

You can simply tap 2 pairs of HU inputs and run into an LOC with speaker level inputs. That was stage one of my Coupe's stereo upgrade when just adding a sub. I didn't cut any wires; I used 4 Posi-Taps and the same 12V source the factory amp used. I used a JL LOC-22, which allows you to bump voltage to 8V. When you hook it up, you run a sine wave test tone and adjust output to just under clipping. What does this do? It gives you max output at minimal distortion. You get super clear lows in the lower volume ranges.

Pink ones are the signals wires, and the blue was power. The LOC uses signal sensing to turn on the amp. You just run a remote wire from LOC to amp remote in.

If you have an amp with built in summing, you could just tap the 4 same wires and the amp will sort the sub signal. Or, since you have a new HU, you just run the 2 pairs of RCAs and a summing amp will create a sub signal that way. It all comes down to the equipment you have.

20210604_002650.jpg

[z3forlife]

The amp separated the sub signal out of the rear full range channel input so no sub channel input was needed. Someone here has a link to a guy that makes a adapter for the stock harness in the trunk to provide pig tail/rca connections.

[s8ilver]

The amp separated the sub signal out of the rear full range channel input so no sub channel input was needed. Someone here has a link to a guy that makes a adapter for the stock harness in the trunk to provide pig tail/rca connections.

Precisely; that's the workaround for 2 pairs of inputs.

A bit difficult to see on mine, but just left of the channel 3/4 input, I can select "separate" or "sum." Sum makes a sub channel from 2 pairs of speaker level inputs, or 2 pairs of RCAs from a HU without sub outputs.

lc-5.1300-front-high.jpgsum.JPG

My Roadster's aftermarket HU had 3 pairs of RCAs so I didn't use it, but I plan to revert to a CD43 someday, and all I'll have to do is tap the trunk harness that's currently tied out of the way and flip the switch to "sum."

[MRobster]

Nathan - Thanks for all the info. Your amp has a ton of features. Mine is simple but I bought it for half price and it seems like a good choice for what I am trying to do (https://www.damoreengineering.com/co...roducts/e660-5).

- - - Updated - - -

I need that adaptor - will search. If anyone here knows who this guy is, please lmk/thanks.

The amp separated the sub signal out of the rear full range channel input so no sub channel input was needed. Someone here has a link to a guy that makes a adapter for the stock harness in the trunk to provide pig tail/rca connections.

[s8ilver]

Nathan - Thanks for all the info. Your amp has a ton of features. Mine is simple but I bought it for half price and it seems like a good choice for what I am trying to do (https://www.damoreengineering.com/co...roducts/e660-5).

- - - Updated - - -

I need that adaptor - will search. If anyone here knows who this guy is, please lmk/thanks.

To add the sub, you'll just need a decent LOC. You could even split a pair of the HU inputs and run those to a RCA style LOC. All the LOC is doing is converting high to low, and a powered version (also known as a line driver) just gives you more oomph. What are your plans for the sub? New woofer in factory box? Something else?

[mobilenet]

Here’s the link to the harness. You’ll see the z4 and z3 pin outs are almost identical. Just let the guy know what you need. He does a nice job of putting it together.

https://www.ebay.com.au/itm/16564647...mis&media=COPY

[MRobster]

Thanks; I wondered about the difference between powered v. nonpowered. Former owner installed the kicker sub speaker in the original box and it does a decent job. While on that topic, though, it's a dual voice coil 2 ohm unit. Only one of the two terminals was being used, so I connected both as it would have been originally. Sounds worse - muddled is the word that comes to mind - so I'll be going back to one set of connections.

To add the sub, you'll just need a decent LOC. You could even split a pair of the HU inputs and run those to a RCA style LOC. All the LOC is doing is converting high to low, and a powered version (also known as a line driver) just gives you more oomph. What are your plans for the sub? New woofer in factory box? Something else?

[dantheman7913]

How do you tell if your car has a single or dual amp HK system? I know my car has the HK package, and I definitely have a primary amp in the trunk on the passenger side. Where would the hypothetical secondary be located?

[MRobster]

The sub amp is in your trunk on the driver's side. There is a plastic hand-twist fastener you can remove to pull back the trunk liner enough to peek in there.

How do you tell if your car has a single or dual amp HK system? I know my car has the HK package, and I definitely have a primary amp in the trunk on the passenger side. Where would the hypothetical secondary be located?

[dantheman7913]

The sub amp is in your trunk on the driver's side. There is a plastic hand-twist fastener you can remove to pull back the trunk liner enough to peek in there.

cool ok definitely don’t have the sub amp then, thanks!

[s8ilver]

If you're planning a 2 OHM DVC sub, you'll need to ensure your amp is 1 OHM stable. Most (all?) 5 channels are stable to 2 OHM, so you'd be looking to install a 4 OHM DVC sub, with a final load of 2 OHM. Of course, you can wire a 2 OHM DVC to 4 OHM, but it'll just be a lot quieter.

PO used one VC as that'd be a 2 OHM load to the amp.

[MRobster]

Can't I wire the 2 ohm DVC sub in series to get to 4 ohms?

If you're planning a 2 OHM DVC sub, you'll need to ensure your amp is 1 OHM stable. Most (all?) 5 channels are stable to 2 OHM, so you'd be looking to install a 4 OHM DVC sub, with a final load of 2 OHM. Of course, you can wire a 2 OHM DVC to 4 OHM, but it'll just be a lot quieter.

PO used one VC as that'd be a 2 OHM load to the amp.

[mpire]

Is this a pre-amp head unit?

All the gizmos in the world won't help if this head unit doesn't have a pre-amp signal.

Otherwise, its just a matter of splicing a few wires in the harness and it will sound dramatically better.

Granted, sounding better than the stock amp with 8% THD is an extremely low bar.

[MRobster]

My understanding is a line output converter will work. As for the install, I can't wait to get started. I cannot live without music in my car!

Is this a pre-amp head unit?

All the gizmos in the world won't help if this head unit doesn't have a pre-amp signal.

Otherwise, its just a matter of splicing a few wires in the harness and it will sound dramatically better.

Granted, sounding better than the stock amp with 8% THD is an extremely low bar.

[z3forlife]

You would not want to wire the sub in series. It will sound like crap. If your head unit doesn’t have a sub output then let the amp do the work. There’s nothing to be gained by inputting a full range signal into a amp sub input. As far as sub choices go a 8” can’t be beat. Choices are limited with the 6” stock enclosure and the earlier 5 1/4” is a total waste of time. There used to be a eBay seller making the 8” enclosure but I think they quit. Making a MDF box isn’t too hard though and the end result is impressive.

[MRobster]

Ok ... I'll find a new shallow 4ohm subwoofer then. My understanding is the LOC handles the signal into the amp's sub input, i.e. it's not full range as a result.

You would not want to wire the sub in series. It will sound like crap. If your head unit doesn’t have a sub output then let the amp do the work. There’s nothing to be gained by inputting a full range signal into a amp sub input. As far as sub choices go a 8” can’t be beat. Choices are limited with the 6” stock enclosure and the earlier 5 1/4” is a total waste of time. There used to be a eBay seller making the 8” enclosure but I think they quit. Making a MDF box isn’t too hard though and the end result is impressive.