RAC68

Hi all,

Installed a full TL Bose system (head, equalizer, amp, and sub) within my 64 Austin Healey a few years ago (see RAC68 Picture Gallery).

http://picasaweb.google.com/lh/photo/68e93jK6aYDrFZNG_4HHrwSeEBT0jmWHGc_vDXI009k?feat=d irectlink[/url]

http://picasaweb.google.com/lh/photo...eat=directlink

http://picasaweb.google.com/lh/photo/YGj9HjHhTq1fkJYF-a4FHQSeEBT0jmWHGc_vDXI009k?feat=directlink[/url]

I have been running only the 2 front channels in the cabin and have installed the amp and sub in the trunk. I have been very pleased with the Bose system’s performance to date but have a few questions I would like help with.

1. Since I am only using 2 midrange and 2 tweeters within the cabin, how can I bridge the 4 channels (2-front, 2-rear) to gain additional power while keeping the left and right separation?
2. I have noticed a hum from the subwoofer in the trunk and was wondering if it would be eliminated if I switch the standard 16/2 speaker wire for Shielded speaker wire in the run from the head unit to the amp?

As a relative sound beginner any help is appreciated.
Thanks all,

fourthmeal

Won't be able to bridge, this amp can't do it (channels do not invert.) Time for an amp.

RAC68

Sorry for my inability to properly present the images of the Bose installation within the Healey. This is another attempt. Hopefully this will succeed.







Ray (RAC68)

RAC68

Well Fourthmeal, that's ends my pursuit of bridging. I appreciate your reply. Do you have any thoughts on question 2?

Ray

fourthmeal

Yes go to twisted pair, like that of cat5 cable or similar. The HU is outputting a low-level RCA-type signal to the bose amp, then of course larger wire from the amp to the sub.

It would cost more but what would look beautiful in that car is a Panasonic Tube double din head unit. The location of your speakers is unorthodox, you probably know this. Placed as they are, there is probably a great deal of incoherence in the soundstage the woofer and tweeter create. Volume, YES. But detail and presence I would wager are "off" a bit, no?

Depends on budget of course, but good audio seems like a worthy investment in a good car.

RAC68

Hi Fourhmeal,

Sorry for my slow response. I took the Healey out for a short warm-up drive in preparation for an oil change to prepare for dry winter drives (20W50 change to 10W40) when the fuel pump failed and put me at the end of a tow strap.

Due to the limits of space, the installation of the mids in the center console was the only location available. I mounted the speakers within baffles to help separate the two, however, with the wind and engine/exhaust noise, the clarity is OK. My desire to bridge the channels was promoted by the fact that, with top down, the volume needs to be cranked to very close to max.

Boy, the Panasonic Tube double din head unit looks great, however, with all the ambient noise in the car, the quality would be lost. I do agree that it would look great.

I found some 2 lead shielded audio cable at Radio Shake. The leads are 24 gauge. Would this gauge be adequate to carry the woofer signals from the HU to the amp? Also, the amp schematic indicates, and the amp has, 2 sets of leads to the woofer. As there are only connections on the woofer, how are these leads connected?

Thanks again and all the best,
Ray (RAC68)

mercman

Before you start ripping things out let’s figure out what you have,
Is the woofer an amplified unit (it would have a =12volt and ground connection) or a passive unit?
The hum or buzz, does it happen all the time, only when the engine is running, or completely random?
Using balanced or twisted pair cable will only help if the source and receiver are balanced, I’m not sure that this is the case with your set up, if you can post the wiring diagram I’ll have a look.
As far as your amp, this would be the one and only time I would recommend using a class D amp, they are small both in size and power drain on your electrical system and will be a big improvement in volume level over the Bose amp.
Jeff

fourthmeal

You don't need a large gauge at all to get the signal from the head unit to the amp. Its a pre-amp signal, minimal power. The factory wiring is shielded, same exact way.

You are best off with a true amplifier, even if you were able to bridge the head unit like you were thinking, it would only be 3dB louder, which is barely an audible difference. A true amp (say a true 50x4) would do well. You could even run an active capable amp like a Soundstream Stealth and you could get the woofers on their own power, and the tweeters on their own as well.