Bose amp bypass?

The Weapon · 04-24-2023, 02:31 PM

Quote:

Originally Posted by NissanParty

I just tapped into the front preouts from the amp and when I turn the bass down on the HU it goes down on the speakers. Does that mean it is not full range? I am planning to use the same signal for the subwoofer, but it won't work if it's filtered.

Does turning the bass down on the HU turn it down on all channels?

by adjusting the bass at the hu it adjusts the bass in the low level signal just like any headunit source would.

If you dont want it effect all speakers then get a sound processor with the flexability to tune each speaker individually.

it is a full signal. This means that from 20hz to 20khm the signal is not crossed-over.

The adjustments you make at the headunit with bass and treble will change the sound. But most aftermarkets headunits do this too.

The sound is not altered at higher volumes either. This happens in the bose amp.

My DM801 has a rta and i could see the full range signal coming just fine when you have bass, mid and treble at 0.

The biggest draw back of the stock bose HU is the voltage output. Its only like 500-700mv. Not that great. Most aftermarket systems are at a minimum of 4 volts these days.

NissanParty · 04-24-2023, 06:38 PM

Quote:

Originally Posted by The Weapon

by adjusting the bass at the hu it adjusts the bass in the low level signal just like any headunit source would.

If you dont want it effect all speakers then get a sound processor with the flexability to tune each speaker individually.

it is a full signal. This means that from 20hz to 20khm the signal is not crossed-over.

The adjustments you make at the headunit with bass and treble will change the sound. But most aftermarkets headunits do this too.

The sound is not altered at higher volumes either. This happens in the bose amp.

My DM801 has a rta and i could see the full range signal coming just fine when you have bass, mid and treble at 0.

The biggest draw back of the stock bose HU is the voltage output. Its only like 500-700mv. Not that great. Most aftermarket systems are at a minimum of 4 volts these days.

Thank you very much. I just wanted to make sure I was really getting the full frequency since I am going to use the same signal for my sub.

Mine is ok without the line driver, I just turned the gain up a tiny bit on the amp. If I got a line driver, would I be able to keep the gain at 0? Would it give me a slightly cleaner sound? Right now I don't hear any noise from it... just wondering if I should buy a line driver or not. A processor would be nice so I could set the timing on the speakers though.

EDIT!!!!: Last night I may have been a little excited to test my new components and amp. Today I was driving and I did notice a very quiet whine with the engine. I could only hear it when no music was playing. So I am ordering a line driver now to get rid of the problem. I don't want any noise at all.

Edit 2: I thought of one more thing. If the signal is going from the factory HU to the factory amp and there is zero noise, where is the noise being introduced when I add an amp? I added a 1 foot RCA cable to the factory wiring from the HU. Is that where the noise is coming in? Why doesn't the factory unit have any noise with that long wiring and low voltage? And the factory wiring is bundled together with the power wire for the amp, but no noise...

The Weapon · 04-26-2023, 12:46 PM

There are may variables that can introduce noise. could be coming from your amps or the wiring from HU to Amps.

Make sure all your grounds are clean good grounds.

To minimize the chance for noise I recommend making sure your equipment has balanced inputs and using the twisted pair rca cables.

I did not have any engine noise at all while connecting this way. However when i did not use balanced rcas and used a cheap line driver without balanced inputs i had horrible noise. So the noise is there but the bose system uses balanced line to the bose amp so it filters out the noise.

My first set up only my processor had balanced inputs. My amps did not. My new setup everything accepts balanced inputs. Both had no noise.

If your amps do not have balanced rca's then noise is just coming from the wiring itself. Balanced rcas send the sound signal through both positive and negative. Whatever is not present in both signals gets filtered out.

As far as gains go, most amps go from ##mv to 4-5v. The lower the gain is set the higher the input voltage from the line level in. IF you are using the the HU then you will probably need to set your gain pretty high before it starts to clip.

I had to set the gain on my processor about 10.5 out 11 in before it started to clip.

The gain has a direct correlation to the voltage output of your source. the Bose headunit in my experience did not clip until it was 1 line away from max.

Here's a simplified explanation -

NissanParty · 04-26-2023, 09:37 PM

The Weapon, thank you very much for the information you are giving me.

I have solved the problem. First I unplugged the RCAs altogether and the whine was there during engine cranking but not when the car was on (maybe I should couldn't hear it).

Since the wires are in a temporary state and not organized yet, the speaker wires were intertwined with the power wires. I straightened that all out and now there is zero noise whatsoever, during cranking or otherwise. It sounds perfect.

Thank you again!!!

bigaudiofanat · 04-27-2023, 02:45 PM

Quote:

Originally Posted by NissanParty

One more question for now!!!

Do the low-level front outputs from the factory head unit have the full frequency range? Meaning can I use that signal for my front woofers, tweeters, and rear subwoofer?

Thank you

Yes they do

bigaudiofanat · 04-27-2023, 02:47 PM

Quote:

Originally Posted by NissanParty

Hello, if I am only going to run a sub and two front components with crossover what is good to use? I really just need it to take two low voltage inputs from the stock HU and split it into sub and front speakers. I am thinking of using a JL 3 ch amp. Can I use a splitter and line driver and rely on the amps LPF and HPF to split the signal for front speakers and sub?

Here is a picture of what I am thinking... would this work:

I would not use a splitter. I would take the full range low level signal and feed it into a DSP. I used the audison bitten but there are plenty of different DSP's out there. This will give you RCA outputs you can set to what you want example Front speakers off one set one set for subs one set for rears

bigaudiofanat · 04-27-2023, 02:48 PM

Quote:

Originally Posted by NissanParty

I just tapped into the front preouts from the amp and when I turn the bass down on the HU it goes down on the speakers. Does that mean it is not full range? I am planning to use the same signal for the subwoofer, but it won't work if it's filtered.

Does turning the bass down on the HU turn it down on all channels?

The pre outs are full range but as weapon pointed out the adjustments will change volume. I'd recommend again keeping all settings flat and use a DSP to set your levels, crossovers and so on.

NissanParty · 04-28-2023, 03:05 PM

Quote:

Originally Posted by bigaudiofanat

The pre outs are full range but as weapon pointed out the adjustments will change volume. I'd recommend again keeping all settings flat and use a DSP to set your levels, crossovers and so on.

I have everything installed, I used a splitter but I can put a DSP in later if I want. It sounds great, zero noise at all now that I have the wires sorted out.

I have an amp with a HPF and crossovers for the components, and LPF for the sub amp. I can set the gains for the front speakers and amp separately.

It was about 1500 for the amps and speakers and everything I needed. I used a JBL BassHub that fits in the spare tire. The only thing that bugs me is it sticks up about two inches. I am still thinking about what to do for that. I wish the spare tire hub did not protrude so much, that is what is making the subwoofer lift up.

04-26-2023, 12:46 PM	#18 (permalink)
The Weapon Enthusiast Member Join Date: Nov 2008 Location: Tucson, AZ Posts: 286 Drives: 370Z Tour/Sport Blk Rep Power: 3372	There are may variables that can introduce noise. could be coming from your amps or the wiring from HU to Amps. Make sure all your grounds are clean good grounds. To minimize the chance for noise I recommend making sure your equipment has balanced inputs and using the twisted pair rca cables. I did not have any engine noise at all while connecting this way. However when i did not use balanced rcas and used a cheap line driver without balanced inputs i had horrible noise. So the noise is there but the bose system uses balanced line to the bose amp so it filters out the noise. My first set up only my processor had balanced inputs. My amps did not. My new setup everything accepts balanced inputs. Both had no noise. If your amps do not have balanced rca's then noise is just coming from the wiring itself. Balanced rcas send the sound signal through both positive and negative. Whatever is not present in both signals gets filtered out. As far as gains go, most amps go from ##mv to 4-5v. The lower the gain is set the higher the input voltage from the line level in. IF you are using the the HU then you will probably need to set your gain pretty high before it starts to clip. I had to set the gain on my processor about 10.5 out 11 in before it started to clip. The gain has a direct correlation to the voltage output of your source. the Bose headunit in my experience did not clip until it was 1 line away from max. Here's a simplified explanation - __________________ Boosted Performance Comp Turbo - Tuner- CJM Fuel Return- Modified Berk CBE- ZSpeed Stage 4 Clutch - Southbend Flywheel - Tuned by Seb ~650whp - HKS Coilovers - SPL - Focal Audio 4 way Active - Audiocontrol DSP - Work CR 2P

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04-26-2023, 09:37 PM	#19 (permalink)
NissanParty Base Member Join Date: Feb 2022 Location: Southern California Posts: 112 Drives: 370z Nismo Rep Power: 32	The Weapon, thank you very much for the information you are giving me. I have solved the problem. First I unplugged the RCAs altogether and the whine was there during engine cranking but not when the car was on (maybe I should couldn't hear it). Since the wires are in a temporary state and not organized yet, the speaker wires were intertwined with the power wires. I straightened that all out and now there is zero noise whatsoever, during cranking or otherwise. It sounds perfect. Thank you again!!!