Quick Speaker Replacement Question

[kpond]

I am in process to replace the Bose amps and speakers. From the Service manuals, it looks like I can pick up the "pre-outs" from the stock head unit. Given this, I would assume that I will not need any line-out converter. Is that correct?

I did a search and found references to some install that were using the line converters. My assumption is that these line converters are used when you have a good speaker-level output and you want to step that down to a pre-amp out levels. Since my Bose amps are shot, my only choice is the pre-amp level outs.
Does that sound right?

 

[D'Ecosse]

That is correct kpond - I originally had exact set-up previously into MTX amp like one you are considering - use the gain control on the amp to adjust the level appropriately. My system had the wires cut & spliced before the plug at the head end - I believe you can may be able to find a Honda/Acura adapter to save that hassle: you may not find it listed specifically for the NSX, but check out some of the other models & you may find the correct harness.

Edit: OK - found it & only $5!! http://www.millionbuy.com/a-ihwh804.html
Now you just need to splice some RCA adapters onto these speaker signal wires - you could run the power from here also, but I would recommend you use a heavier gauge wire direct from the battery.
http://www.nsxprime.com/FAQ/Reference/1991_svcman/1991servman.pdf - go to page 1220 for a quick reference to the wire colour/pin ID's for each channel.

 

[4Chin500]

I'm not sure the cable shown in this URL is the correct gender to accomplish what needs to be done. A male connector is needed to plug into the back of the head unit to provide the low level left, right, and sub signal wires to attach the RCA connectors to. Ideally you would mate a male cable connector to the female cable shown in the picture to create a splice cable. In this way you could easily splice between the factory head unit and the car's wiring harness, breaking out the signals you need. Unfortunately I do not know where to locate a suitable male connector...short of finding a salvage NSX and cutting out a portion of the original harness.

 

[NSX/MR2]

I know where there is a "salvaged NSX" locate. A junk-yard name "Import Junk-yard" located in San Diego close to Chula Vista/National City has a red one. That car still has ton of stuff. How do I know that? (That car was my last NSX, crashed about eight months ago.)

 

[D'Ecosse]

I'm not sure the cable shown in this URL is the correct gender to accomplish what needs to be done. A male connector is needed to plug into the back of the head unit to provide the low level left, right, and sub signal wires to attach the RCA connectors to. .....

OOPS! sorry, should have been http://www.millionbuy.com/aihwh805.html which is the male plug to fit into the radio - the 804 adapts to the harness plug.
Actually, the best plan is to buy the 804 & the 805 - then you can plug the 804 into the factory plug, connect the power wires of the 804 (ignore the signal wires of the 804) to those of the 805 & the signal wires of the 805 to the RCA's. Then the 805 plugs into the head. This way, you will have a harness that will not involve any cutting of the stock factory harness.
Hope that makes sense!

 

[kpond]

D'Ecosse,

Thanks for all of your input (and pictures). You've already done exactly what I'm in process to do. I shopped for components that has a relatively small crossover to mitigate the fitment issues that you dealt with. I found that the MB Q's had a small circuit board that would fit in the stock enclosure... as long as I removed the small plastic case surrounding it.

I ordered the 804 and 805 connectors per your links (thanks). I mounted the speakers in the MDF and tested them with my home (garage) receiver. I'm not sure I really like the sound so I'm thinking of putting in a forward facing 1" port. There's a self-professed speaker design guru at work so I am going to consult him tomorrow.

Anyway, I appreciate your assistance.

 

[D'Ecosse]

kpond, glad I could help so far
I wouldn't base too much on how the speakers sound in open environment in your garage - I think if you install them in the doors (please use the dynamat, worth the $$$) you will find the imaging with the cabin closed up to be quite different - what are you doing about locating the tweeters? I know people who have mounted them on the baffle next to the mid-range, but again your imaging will suffer - it really depends how much you value your stock door panels & if you're prepared to cut them. The location where mine are is about the only place they will go - if I recall the MB's are a bit smaller & possibly you could surface mount them on the side-window-front-corner-triangle-trim-piece (or whatever it is called!)

 

[kpond]

Since the speaker enclosures are sealed, I'm not sure the influence of the speaker's sonic changes when located in the door. I at least want to hear what my buddy says about porting them. I'll let you know what I decide.

By the way, what did you do for speaker wire? Did you run new wires into the door? I hooked up the stock Bose plug such that the former power and ground wire (16 gauge at least) are now running to the speaker. I didn't thing that the pre-amp in wires in the door were of sufficient size to use. Now I have to intercept the connector up under the dash so I can tioe in the speaker wires from the amp. Unfortunately, to get at this connector, you MUST remove the dash. Oh well, I've wanted to replace the small dash trim piece that cracks near the center for a long time.

Regadring the tweeters, yes I can fit them in that small triangle piece. Here's a terrible picture. Basically, they are mounter on an angled circle that tilts them directly toward the listener.

 

[D'Ecosse]

Did you use the stock rear Bose shells? I cut the rear off mine behind the speaker so they are ported into entire door cavity effectively.
The tweeters should be great up there - mine are quite a bit larger again, so didn't have that option.
Yes, I ran speaker wire - it is a bit of a mother but possible to pull it down through the stock harness into the door - the only awkward part is just that one rubber sleeve section between the door & the bulkead. I used a "fish" (in the form of some solid 12 ga copper wire folded over at end) to go from inside the door back up towards the bulkhead - it was easier to disconnect the "grommet" style fitting at each end before fishing; I had a hard time pulling the wire back through however because there isn't much space - so instead of traditional method of looping through the end of the "fish" I cut off the loop & soldered both of the speaker wires together to the end of the copper wire - this made for minimal bulk to pull back down through. The speaker wires come back over under the dash towards the head unit unit then in my case back down the centre console over the firewall & out to the trunk - you will have much less distance to run of course.
The problem with using the power wiring to the doors is that it is difficult to see from the wiring diagram where to intersect it along the routing - the grounds to both door amps are tied together & the supply is also commoned with the footwell unit & they are fed from the power amp relay. It doesn't seem possible to determine from the schematic where the ties takes places.
I think I used 12, may have been 14 ga - figure it from the pic!

 

[kpond]

D'Ecosse,

Ohhhh, you cut the backs off. Mine are still on. OK, so I think my "enclosure" is really too small to be effective. I will either port it to the front or cut the back off - like what you did. I'm leaning that way. I will definitely use the dynamat.

In terms of finding the connectors, it is REALLY EASY with the shop manual - the ETM one, that is. This manual tells you where all of the connectors are and even has a whole section of pictures showing their location.

 

[D'Ecosse]

I have the helms shop manual - guess I just wasn't looking in the right place. Don't let me put you off doing the "real" speaker wire - it wasn't trivial but obviously its do-able - I messed with the speaker wire looped around the pull wire for the longest time then also tried a long parallel/overlapped taped approach on the pull wire, but both were way too bulky - soldering made it really much easier & then I just cut it off after it came through! If you go straight to this method it will save a lot of agony
Yes, when you think about it, even the stock enclosures have a port for the puny bose speakers, but its on the front half of the shell, so you lose that when you mount the mdf plate - that is no volume at all to let those 6.5" speakers work. I just sliced off the very back face of the circular recess.

 

[kpond]

D'Ecosse,

Thanks for the tip on the harness connectors. I bought both the male and female and made up a harness with the pre-outs to a standard (if you consider purple standard) RCA out. The longer wire is the "trigger on" wire for the amp.

 

[D'Ecosse]

Beautiful job K - this one belongs in the FAQ!

 

[kpond]

D'Ecosse,

Thanks for the compliment - but look again at the harness! Thankfully, I did a trial hook-up and got absolutely NOTHING out of the speakers. I pulled this harness back out (very easy as I still had the car apart) and took a closer look. Do you notice which end of the harness I put the RCA connectors on?? Hahahahahaha, I had them on the wrong side. Instead of picking up the pre-amp outs as they come out of the head unit, I was tring to get them from the other side. What a bonehead! Oh well, it was easy enough to switch. I have plenty of heat shrink and solder!

 

[D'Ecosse]

You'll think I'm being pig-headed, but actually I did think it was wrong end - was working off memory so didn't comment, thought I must be wrong because I was confident you would have it right!

Did something dumb myself today - installed a flux capacitor (that's what the missus calls it! - actually a smoothing 1F cap for the amp power supply - also got a nice new yellow top Optima!!!!!

); after I put it all back together got nadda out of the amp on the left channel - pulled it all out thinking I must've broken a wire or something - messed with it for a good 30 mins before I saw I had moved a switch by accident - doooohhhh!!!!
These things just make us mere mortals ....
So I'm convinced it sounds better after spending $300 ....... I'd have to be wouldn't I? (well it needed new battery anyway ...seriously I do think the bass is much stronger with the combo of both)

 

[kpond]

Here's a quick pick of the amp in its place within the former subwoofer enclosure. The height of the amp at its tallest point is the same as the original box. I'm going to put a couple of strips of foam tape at the tall point before placing the aluminum floor plate on to cover everything up.

I fired the system up tonight (after fixing the connector mentioned above, and it sounds absolutely great. My assessment is that it is MUCH better than stock. Very clean sound, very punchy mid-bass. VERY crisp highs. A sub will definitely be an improvement but my goal was to be significantly better than stock. I achieved that and at a total cost of less than $400. I would highly recommend others to seriously consider this as an alternative to pouring money into Bose replacement components.

 

[D'Ecosse]

Excellent job - glad the results are justified which is what is most important - I remember getting pooh-poohed a few months ago when I suggested that a decent alternative that would offer improvement over stock could be done for ~$500 - thanks for validating that!!!! (with $100 to spare even .....)
Yes, a sub can add more punch at the lower end than what you currently have - however people need to realize what the starting set-up is - to think you can get decent bass from a 3" speaker is a joke, so I am in no doubt your 6 1/2"'s are a vast improvement, even w/o a sub. I can guarantee I can turn my sub off & it will absolutely blow the doors off a stock system leaving no-one in doubt there is much greater range than the piddly Bose.
You going to be at 'xpo? would like to see/hear in person.

 

[D'Ecosse]

I mounted the speakers in the MDF and tested them with my home (garage) receiver. I'm not sure I really like the sound ... There's a self-professed speaker design guru at work so I am going to consult him tomorrow....

Incidentally, kpond - what did your expert say about the "enclosure" design (venting the rear)? I'm curious ....
Also I'm assuming it made a big diffference once they were installed compared to the initial experience in the garage?

 

[nsx_parts]

I bet that amp will keep your feet warm in the winter!

 

[D'Ecosse]

Originally posted by nsxparts.com
I bet that amp will keep your feet warm in the winter!

Actually thats one thing that may concern if its running at high output - especially wrapped up under the carpet, there's probably little outlet for the heat - hadn't thought of that, it'll be interesting to see how that works out - I guess you'll still have the aluminum kick plate which will allow a little air between the amp & the carpet?

 

[kpond]

Well, my "expert" is a mechanical engineer with only a passion for audio and speaker design in particular. To achieve the most bass response and overall sound accuracy, I asked whether it was better to have a completely sealed but small enclosure (small air volume), ported to either the front or the back with a port diameter of virtually any size I choose, or a completely open design with the back open and the thought to utilize the entire door air volume. His answer - "I don't know."

Allegedly there is no right answer. Honestly, I was kind of hoping there was a right answer and then I would just do it! I also consulted the car stereo store where I bought the speakers (mid to high end stuff), and they were much more opinionated. They believed that the sealed approach was best. OK, so that's what I stayed with. Trust me, it sounds real good.

Regarding the issue of amplifier heat. Yes, I did think of that... and I have even thought of the potential need of a small fan. However, I really doubt it will be necessary. First, there is some dead space back behind the aluminum plate. So, there is som air volume that can help the amp to dissipate heat. Second, and probably a bigger factor, the amp is barely working at all even at moderate to loud levels. Let's face it, the cabin of the NSX is relatively small and it doesn't take that much power to drive this single pair of speakers.

I'll give some feedback after I've had a chance to live with it in the real world.

 

[(NSX REY)]

Kpond- Very nice work! Is the wire harness in the picture the one D’Eccosse suggested (1986-98 Honda/Acura Harness) HWH-805? I would like to do away with my Bose system as well, and would like to go the route you have. Please consider doing a step by step write up in the DIY or FAQ. Your knowledge of this modification would help others accomplish a similar task.

What series of MB Quart's did you go with, and what amp are you using? (Power output...)

 

[kpond]

(NSX REY),

Yes, order both the 804 and the 805 connector from www.millionbuy.com. They were very fast to ship - no problems. I would highly recommend the MTX amp that I purchased. I'm not at home, but I think I previously mentioned the model number. Perhaps it is BS, but each amp comes with an "as test" score card. They are rated at 50WPC at less than 1% distortion. The paper that came with mine (and I'm sure they are all virtually the same) said it measured at 74WPC at less .014% THD. The amp has a set of RCA in's AND a set a RCA out's. So, if you ever wanted to add another amp or otherwise tap into you line level input, it is easy. Another thing that I liked is that it turns on/off very quietly - no "pops". Best of all, it fits in the stock subwoofer enclosure.

Last night I installed the aluminum floor plate and I was once again convinced more than ever that heat will likely NOT be a problem. The aluminum floor plate is much closer to vertical than the amp is. The bottom almost touches the bottom edge of the amp, but I think there's 2" or more at the top. I think this will provide sufficient air space - especially at most reasonable listening volumes.

I'll consider a cohesive write-up when I've got some more time.

 

[Hugh]

D'Ecosse,

Thanks for the tip on the harness connectors. I bought both the male and female and made up a harness with the pre-outs to a standard (if you consider purple standard) RCA out. The longer wire is the "trigger on" wire for the amp.

I followed D'Ecosse's advice as well and got both connectors.
I'm going to have 3 RCA outs though since the amp I'm using, JL 300/4 has a seperate input for the subwoofer and it is fully adjustable as far as crossover points are concerned.

I think what I'll probaby do differently than your setup is use female connectors and make them as short as possible allowing me to run high quality male to male RCA cables from the harness to the amp. The amp is going to be located in the trunk.

What are your thoughts on this approach?

 

[Hugh]

Now you just need to splice some RCA adapters onto these speaker signal wires - you could run the power from here also, but I would recommend you use a heavier gauge wire direct from the battery.
http://www.nsxprime.com/FAQ/Reference/1991_svcman/1991servman.pdf - go to page 1220 for a quick reference to the wire colour/pin ID's for each channel.

Can someone clear this up for me please.....

The pin-out diagram on page 1220 of the online manual shows 2 sets of foot well outputs, one for the passenger's side and one for the driver's side. Now we all know there's no sub on the driver's side.

Looking at page 1216 of the manual which is the schematic these 2 pairs of signal wires (A7-A15 and A8-A16) (there's a typo in the manual by the way on page 1220, it shows two A6 terminals, the second one is obviously A8 as the schematic shows) ....anyway......both sets of signal wires go the bass amp in the passenger footwell. Which set do I use to send a signal to my new bass amp? My guess is that either set sends an identical mono signal but does anyone know for sure? Would it be safe to wire both outputs to one RCA cable effectively creating a "Y" adapter?

Thanks,
Hugh