D3 whining - Bose amp bypass???

[davidard]

I installed a D3 in an '04 Chevrolet Silverado 2500 and love the unit but am getting the whining that many others have experienced. Here are the specifics

 

Avic-D3

Factory Bose amp and speakers

Bluetooth adapter

XM Radio

2x closed loop isolators (this help, but haven't eliminated the whine, but they kill my mid-ranges).

 

I talked to the Best Buy installer and he told me that the issue is created because the D3 has an amp and it is directly connected to my Bose amp. He said the solution is to bypass the Bose amp and go directly from the head unit to my speakers. I've never heard of that solution before so i'm curious if anyone else has tried that.

 

I also read somewhere that bypassing the Bose amp will will significantly impact the volume i can get out of the Bose speakers since they are specifically designed to work with the amp. Is that true?

 

Has anyone tried bypassing the factory Bose amp before? Will this kill the whine? If it does, i'm considering just buying new, better speakers.

[HiFiSi]

You can't run the bose speakers off the D3's amp. The Bose speakers are 2 ohms, which will make short work of the D3's amplifier. If you are going to bypass the Bose amp, you'll have to replace the speakers.

 

Either buy a line level converter so you can control the gain levels of the signal boing to the Bose amplifier (I'm not even sure if that would fix it) or bypass the amp and replace the speakers. I personally would go with the latter. Bose car audio equipment is CRAP.

[davidard]

THanks - one more question - would installing a Metra GMOS-04 allow me to take advantage of the bose amp and speakers?

 

I agree on getting new speakers - just trying to leverage what i have until i'm ready to buy.

[HiFiSi]

I had to look a bit to find this quite that i posted a while back... but it's from a guy I knew who used to work for Bose...

As for power output, I'm embarrassed that I don't have the exact spec, but it's not much more than 15-20 watts rms per speaker. Unless already familiar with the required math, though, these figures can't really be compared with other aftermarket equipment. BOSE generally uses speakers with an impedence of roughly 1 ohm, compared to the common 4-ohm rating on most widely available components. The BOSE speaker places far less load on the amplifier, allowing lower power output to be used to achieve a given volume level. A BOSE power spec would be rated at the lower impedence, but if connected to a 4-ohm speaker, the actual output would drop significantly. If BOSE speakers are connected to a conventional amp, it'll most likely destroy the speaker AND fry the amp. Most conventional amps can't handle the 1-ohm load. DO NOT TEST THIS THEORY UNLESS YOU HAVE DISPOSABLE COMPONENTS!

[HiFiSi]

THanks - one more question - would installing a Metra GMOS-04 allow me to take advantage of the bose amp and speakers?

I don't know... Ive never had to physically deal with one myself. I'm not sure what's required to interface with them properly. But looking over at metraonline.com, that's the part it specs out for integrating an aftermarket radio into the factory system.

[davidard]

Thanks for your feedback. I'm going to try the GMOS-04 tonight and see if that fixes the problem. If not, i'll scrap it all and just go with new speakers.

[shotgun_customs]

The Bose speakers used in the GM truck/SUV systems are 4 ohm and the amp can be by-passed to connect the speakers directly to the radio. Bose speakers are typically lower in impedence, Nissan Bose, but not on the GM. If you use the GMOS-04 it won't matter.

[HiFiSi]

Hmmm... Cool. I though ALL the Bose setups where like that. Good to know, I guess.

[davidard]

Just to close on this issue, i installed the GMOS-04 and that completely fixed the problem. Plus the volume levels are much better now. That did the trick for me!