Last updated: June 14, 2002
by Wade Lanham
Many of you have questions about upgrading or changing parts of the factory stereo
systems of a 3rd gen. I'll describe some things I've found about the factory systems and
some methods of upgrading. This FAQ assumes you have a basic knowledge of car stereo wiring.
The Bose head's outputs are at a low level. How low, I don't know. They aren't compatible with the inputs of my Sony amp. I used an inexpensive hi-low level converter to use the Sony aftermarket amp. I've heard of people using the Bose head outputs right into an aftermarket amp. This might work on some amps. I'd say that using a hi-low level converter (in place of the Bose amps) will allow you to use practically any aftermarket amp.
The power to all the Bose amps are on a +12v 30A relay that is switched on when the stereo comes on. This power isn't enough for most aftermarket amps, so if you install amps, you better use the power lead (meant for the Bose amp) to turn your amp on and off, and run a new fused +12v lead from the battery or fuse box to power your amp.
The STANDARD head's outputs are high level, as expected. Just use hi-low level
converters anywhere you want to use an aftermarket amp. You should be able to use the
LG/B (light green/black) wire that goes to the center channel amp from the head unit to
turn your amps on and off. It is a low amperage +12v that comes on when the head unit is
A common modification is substituting different speakers for the Bose speakers and using the Bose amps. This is okay, but keep a few things in mind:
If you decide to change speakers, you need to try to match the resistance as closely as possible. Most 4 ohm car speakers will work, but you will lose some volume. I don't know how easily you can find 2 ohm speakers.
If you plan to use aftermarket amps later, after putting in aftermarket speakers, then
the 4 ohm speakers might not be a big deal. You'll just have to plan ahead if you want to
upgrade in stages.
This is very common. You'll need base model carpet and cargo cover to really look right after removing the Wave.
Use a hi-low level converter on each rear output and your choice of amps and speakers.
This is a reasonable option for those not wanting to lose their spare, or those who want to keep a mostly-stock appearance.
For more bass volume, an aftermarket amp can be used with hi-low level converters in place of the Bose amps. I tried this with the low pass filter built into the amp, and it is pretty loud, but of course the Bose speakers distort quite easily.
I suspect that removing the two subs and using a single 6.5" high quality sub with a high powered aftermarket amp would give much more volume and clarity from the rear. From what I've seen (and heard), isobaric speaker configurations are lower volume and distort more easily than ordinary speaker setups. I will try this substitution shorty.
Simply pulling the two rear speakers and using a single 6.5" high quality driver with
the Bose amps might improve the sound quality tremendously. I haven't tried this yet either.
If you have something to add to this FAQ, or have questions, email Wade Lanham or check for me on the rx-7 mailing list.
Someone mailed this to me. The original author is listed as "Gordman". Sorry I don't have more info on him. --Steve
I worked for BOSE in the late '80's as a Manufacturing Engineer, and now that I have a '90 NA Coupe, I thought I'd attempt a single comprehensive discussion to address all the BOSE questions I often see here.
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!
If considering upgrading the stereo, understand some of the system design elements. Each BOSE amplifier contains active equalization circuitry tailored to the specific driver (not you, the speaker!) characteristics and the location of each original BOSE speaker. In addition, the speakers are mounted in ported enclosures (the big, odd-shaped black plastic boxes). The air volume and port tube (hole in box where the air comes out when the speaker's working) size are designed to resonate at a specific frequency to enhance the bass response of the BOSE driver. If mounting aftermarket speakers in the stock enclosures, use aftermarket amplification, and it'll take a fair amount of effort to achieve a good physical fit due to BOSE's unique speaker sizing.
The rear 6 1/2" isn't bad, although because the speaker is covered up so much, it won't get very good highs without a separate tweeter placement. Luckily, unless using rear speakers only, most of the stereo imaging in a well-designed system should come from the front speakers anyway. This produces the desired front-biased soundstage, and a good coaxial will suffice for rear fill. Note that these are simply the most commonly held opinions of how car audio should sound. There are many other theories, so use your own ears. I personally prefer the sharp detail of separates all around!
The front 3 1/2" presents more of a problem, and doesn't allow for an easy direct replacement. With modification, 4", 5", or 6 1/2" speakers can fit, preferably with separate tweeters mounted in the dash (better imaging than door-mounted tweeters). Experiment with plugging the port tubes to see what gives the best sound with the new speakers. Due to these unique aspects of the BOSE design, simply adding 4-ohm aftermarket speakers to the BOSE system doesn't work very well. The sound would be weak and have terrible frequency response. Spend a little money and avoid the hassle, these installation difficulties are easily overcome by any good professional installer.
BOSE manufactures their own speaker drivers, enclosures, and amplifiers from scratch, using their own proprietary specifications, which make them incompatible with the general aftermarket. The head units however, are relatively standard DIN chassis, sourced from quality manufacturers like Panasonic (the heads BOSE used to sell in their old BOSE-branded retail systems), and Clarion for Nissans and Alpine for Hondas (It's been awhile, so I might be wrong on one or two of these, but they're all familiar brands). They're not high-end components, but they're certainly solid enough for a modest system if they're still working properly. It's possible to get adapters for these through stereo shops to keep the stock head unit and upgrade the amps and speakers.
In creating their OEM systems, BOSE designs each system individually for the intended model. A special dummy head with electronic "ears" is actually placed in each seat at proper listening height to gather acoustic data that's processed by computer in an effort to achieve the desired sound curve. The Z's particular interior acoustic characteristics were analyzed, and equalization curves are set on the individual amplifiers to provide proper frequency response and stereo imaging for the occupants' listening positions. Some systems, like our Z's, even use a fifth speaker as a front center channel. This compensates for the loss in imaging that occurs due to the fact that the speaker on the door is much closer to your ears than the speaker on the opposite door!
In general, the BOSE system is a decent quality OE system that uses some interesting acoustic technology to achieve reasonably good frequency response and nice stereo imaging at low-to-moderate volume levels, but its "crankability" is pretty weak. The end result is technically, pretty good sound, but not everyone necessarily agrees with BOSE's (as defined by Dr. Amar Bose himself) definition of goodness. It is definitely NOT, nor was it intended to be, as kick-ass as with aftermarket components, but IF everything is still working properly, it's a pretty good system for those with modest audio needs. For those that want to make truly satisfying upgrades, plan on replacing the entire system, like I am.
Oh, I almost forgot, the loud scratch and pop sounds that occur when turning any electronic volume knob are almost always due to oxidatation of the volume pot (potentiometer). Huh? The internals of the volume control get dirty or corroded and can't make good electrical contact. Get some 'Tuner Cleaner' from any electronics store (Radio Shack), then remove the volume knob and try spraying a LITTLE bit down along the volume shaft. It needs to get inside the part that actually rotates when turning the volume knob. I haven't done this on my Z yet, so I don't know how difficult it is to get enough fluid into the right places (and out of the wrong places!), but I do have the symptom, and I know the sound well from my guitar amps. This is a common electrical problem in many devices, and tuner cleaner is usually the best fix short of dis-assembly.
Date: Fri, 11 Aug 2000 22:46:11 CDT
From: "Bowen Nowon" (email@example.com)
>I am wondering if the non-Bose head unit may overpower my amplifiers. I >seem to remember that the Bose units amplified the output (making me >think that the output on the Bose head unit is lower than the non-Bose >unit).
There is no diffrence in the output of the headunit. The Bose sytem and Non-Bose system use the same headunit and CD player. The diffrence in the systems is the speakers and amplifiers. Both systems use a center channel and amplifier. The bose system uses 2 4" mid range drivers in enclosures in the front doors with an amplifier in each enclosure, where as the Non-Bose uses 5 1/4's with no amp. The Non-Bose also gets 6X8's in the rear where as the Bose gets pockets. The Bose has the famous Bose labyrinth Subwoofer in the trunk with its own amplifiers as well.
>Or am I stuck, and just need to spend a few hundred dollars on power-in >amplifiers that I don't want to buy?
You can replaced the headunit in the bose system. However you have to wire the amps to turn on. Otherwise its simpler to bypass the amps and use the radio's power. The Bose amp is only 15 to 20 watts at each speaker. The reason why most people think there is more is because all Bose systems use lower ohm load speakers which bring the sound closer to the occupants in the vehicle. All other systems use 4 to 8 ohm drivers as to the 2 to 1/2 ohm that are in most all Bose.
Issues you must reslove when using an aftermarket headunit on the bose speakers. You need to find a quality unit that can handle to lower resistance of the speakers. Its also best to find one that will crossover the rear output to bass only. Some Alpine and Pioneer units can due this. Panasonic makes some that produce extremly high power at these ohm loads. If you decide to wire the factory amps to work the Bose speakers be forwarned that you may recieve noises such as Pops crakling and fuzzy sound at high volume levels.
For Bose, I recommend to replace the speaker's in the doors and add a good amp with croosover to use the Bose sub. And if you have the money bye the brackets and grills and add some rear speakers.
Date: Tue, 11 Jun 2002 07:48:31 -0700
From: "Jeff Foster" (Jeff@step4.com)
Subject: RE: (rx7)  Possible to use new deck with BOSE speakers?
>I am wanting to buy a new cd deck, but I am wondering if it is possible to >install a new deck and use the existing BOSE speakers? I am sure it is >possible, if it is do I have to still use the tape section of the head unit >in conjunction with the new deck or can the new deck be used all on its own?
I pulled my bose stuff out and wired in a new harness, so I don't have first hand knowledge, but I've read several places that the Scorche harness from www.crutchfield.com can allow you to do this.
Date: Tue, 11 Jun 2002 11:28:45 -0700 (PDT)
From: Greg Bartley (firstname.lastname@example.org)
Sure does, I'm using one right now on a Kenwood Z828 deck. Works fairly descent if you don't feel like ripping out the Bose system.
Date: Sun, 19 Mar 2000 16:10:42 -0800
From: Azeem Raja (ARaja@KestrelSolutions.com)
Just some obscure info if you ever want to use your Bose system without a CD player, meaning just the radio.
The CD player is wired in 'series' with the radio... so if you remove it, the radio stops working. To get just the radio working, requires a 'jumper plug' which connects the signal paths together, as if the CD-player was there.
The dealer is supposed to have this part, but the dealers in my area were completely clueless (the plug is not on the parts microfiche).
So I built one:
Key X----X X----X X X X X X X X X X
(Figure courtesy of: Steve Stover - View with fixed width font)
Date: Sat, 23 Sep 2000 16:04:47 -0400
Subject: Re: [TRI7] (rx7) (3) Speaker Wiring
Yellow/Green: Rear Left speaker + Yellow/Blue: Rear Left speaker - Blue/White: Rear Right speaker + Blue/Yellow: Rear Right speaker -