Horrible audio signal when tapped into sub input

[nom3rcy]

OK this is a long post, and I typed it quickly so bare with me, but long story short - tapped into the amplified signal at the factory subwoofer and it turned out to be of absolute horrible quality, ended up running just the front speakers and it sounds way better. Will do the full install next weekend.

The components I have chosen are JL Audio HD900/5 for an amp, DynAudio 240mkII 5.75" components, and a Kicker L5 10" sub.

I am impulsive and impatient, so I decided to install the amp and grab a signal from the factory sub just to get some extra bass while I wait for my Dyns and some other stuff to get here.

Install went well, probably one of the easiest I have done due to the close proximity of all the necessary tap-ins (power,ground,remote,signal,etc)

I turned the gain on the amp all the way down, and connected the RCAs I spliced into the sub harness (per BSW's info) and turned on the car.

I could hear the bass but at each 'kick' there was noticeable distortion. This was on my test sub, so I thought it may have been blown, so I threw a 15" Kicker on there. Still distorted. Threw the L5 on there... still distorted.

Crap. The signal is horrible...

It also was cutting in and out, missing some notes and playing others. Very very odd performance.

After tweaking the settings in DSP and TONE menus, I got it playing at moderate volume levels, but noticed that there seemed to be a floor around 50Hz where the bass would muddle together, almost as if the processor changed the frequency to be higher instead of just attenuating it.

It was also still cutting out and distorting, so I abandoned the project until my DynAudios come in and will tap into the signal before the DSP amp (by removing the DSP amp and resetting the system it changes to a balanced output) and it should be a nice clean 5v signal.

I guess I am just wondering if anyone else has had this sort of problem. I don't see how it is remotely possible to get a decent signal from the factory subwoofer channels, unless there is a problem with my DSP or amplifier that is causing this to begin with.

Which leads me into the next part of my post...

After removing my amp and buttoning it all back up, I left the factory sub out as I wasn't confident that it was getting a good signal.

I got back in the car and started messing with the DSP to see what I could do with the factory speakers, sans sub.

I ended up setting the fader all the way forward, the 80Hz EQ all the way up, and the rest resembling the curve as suggested in the FAQ.

It sounds great - just the front stage all by itself. No rear speakers, no sub, it sounds the way it is supposed to. Bass and guitar notes were clean and defined, vocals were staged well, and save for the crap quality of the factory speakers you can say I was very impressed.

So I am thinking that there must be a serious problem with my factory sub output that was throwing off the whole system. Now that it is gone it sounds so much better.

Still can't wait for the Dyns, but this will do for now...

[nom3rcy]

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[Laurence]

RCA inputs are generally 1 volt peak to peak, an amplifier output is generally 12 - 24 volts peak to peak when turned fully up.
If you have connected the DSP sub outputs (i.e. the speaker connectors) directly to the RCA connectors then you are probably over driving the amplifiers input stage and causing distortion and clipping.
Do you have a "high level input" on your amp? If so, connect the DSP sub speaker wires to that.

[nom3rcy]

Yes it does have speaker-level inputs which I did use for this installation, part of the reason why I chose this particular amp.

[hunds02]

you can buy a LOC for less than $10, tap into your rear speaker, bass response is excellent for having a factory head unit

[nom3rcy]

This amp doesn't need a LOC.

I finished the rest of my install a couple of weeks ago - picked up the signal from the factory tuner after deactivating DSP.

Sound quality is excellent now. I think there was something wrong with my DSP amp.