These units are inexpensive all-in-one Pro Logic / Dolby Digital mini theater systems. While my hacks/observations apply specifically to these models, I'm sure other models (even other brands) are similar.

DISCLAIMER: I have no affiliation with Aiwa corporation or its employees. All information is based on my own findings. If you modify your unit, you'll void the warranty. I hold no responsiblility if anything bad happens. If you damage your system, hurt or kill yourself, it's your own fault.

There appears to be a couple of variants these. Some pairs have white midrange drivers (see picture above), others have black. Mine has black drivers.

The speakers have two distinct qualities: weak midrange and boxy sound. So lets open these up and see what's going on. The first thing you'll discover is there are no screws or panels that come off to service these. They are glued together. To access the drivers, you have to carefully pry the plastic faceplate. There are two small notches at the bottom of the speaker to get started. The faceplate is glued on to an inner plastic panel with a rubber cement (same consistency as the glue from a hot-melt glue gun), so be slow and steady when you pry. I ended up with pry marks on the bottoms of both speakers, but they don’t show. It will be stiff at first, but the faceplate will begin to separate. Note there are six points where the faceplate is glued onto the inner plate: 2 at the top corners, 2 at the bottom corners, and 2 in-between.

OK, now that the hard part is done, you can finally see the drivers. Sure enough these speakers are 3-way's (unlike your typical Yorx or GPX speaker where a driver is either a sticker or painted on). Fortunately, with the exception of the dome/piezo tweeter the drivers are attached with screws.

Remove the woofer, and see what's behind: a hollow box, no acoustic foam, insulation, not even a sock. Add some insulation or acoustic dampening foam to cut down the boxyness. I cut a section out of some owens corning pink insulation (R19). Other materials will probably work just as well.

Next, with the speaker connected to an amplifier, disconnect the midrange/tweeter and listen to the speaker, then disconnect the woofer and do the same. You may notice nothing really reproduces midrange sounds (it's not the fault of the Aiwa amplifier). The best I can tell is that the 6in woofer is not doing a very good job as a full range driver, and the "midrange" driver has a very high frequency filter capacitor (2.2uf) in line. So there are some choices. 1: replace the 6in driver with one that does a better job producing midrange, or 2: lower the crossover frequency . Replacing the 2.2uf capacitors with something larger (6-10uf) lowers the crossover frequency, and the midrange driver does a much better job. (BTW, remember to use nonpolarized capacitors.) It might even seem like too much midrange. A low ohm resistor can help in this case. The (super) tweeter does not emit much sound, but it does work and needs no modification. To be on the safe side, I left it connected to the original 2.2uf capacitor. The best solution would be to use a real crossover, but we are cheap, that's why we bought an Aiwa to begin with.

The drivers are 4in full-range speakers. The center channel is shielded, the surrounds are not.

Taking these apart is much easier than the mains. They're nothing more than plastic boxes with 4 screws hoeing them together. There are two major problems with these speakers 1: lack of dampening material, 2: filter capacitors!. I'm not sure why Aiwa used filter capacitors on these speakers (especially the center channel). It's possible they are tuned for Pro Logic systems, or maybe the empty plastic boxes would resonate badly at lower frequencies (more likely). Either way, the right thing to do is stuff the boxes with insulation and bypass the capacitors altogether. They sound 100% better now. The center channel still lacks the deep lows and highs a good center channel speaker is capable of, but the sound is much fuller than it used to be.

* Note there's some stiffening posts inside the center channel speaker. Mine came lose and needed to be reglued.

Same thing as above, just an empty box inside. Being a subwoofer, the boomy bass might be a good thing depending on what you're listening to. Use your best judgement here.

Most PC's and lower cost DVD players (Apex for example) only have coaxial S/PDIF outputs. You could spring the $50 for a coax to toslink converter, but if you are handy with a soldering iron and some basic electronics, it's not too hard to add a coax input.

The Dolby Digital and digital input components live on the small circuit board attached to the rear of the unit (where the optical connector is). There are two main chips on this circuit board:

o Crystal Semi cs8415a-cs digital audio interface receiver

o Crystal Semi cs493263-cd Dolby Digital/DTS processing unit

First, get the datasheet for the cs8415a at crystal's website. The file is cs8415a-3.pdf . The Aiwa receiver operates this chip in "software mode" and the digital data input is on pin 12. You need to construct the simple circuit illustrated on page 39, fig 14. However instead of input going to RXP0, it goes to RXP1 (pin 12). Also don't worry about RXN0, it is already clamped to ground via an on-board .01uf capacitor.

So the components needed are:

1 RCA female connector

1 75 ohm resistor

1 0.01uf (103) capacitor

1 optional spdt switch (to switch from coax/optical inputs)

The trace that currently goes to pin12 is the optical data input. You'll need to control which input you want via the spdt switch. In my case, I just lifted pin12 off the circuit board and exclusively use the coax input (I have nothing that uses optical anyway).

If you read the datasheet, you'll find that the cs8415a is capable of 7 separate digital inputs (aka 7 DVD players or soundcards) and can switch them in software via the MUX2:0 register. It's unfortunate the Aiwa firmware forces input to be RXP1 only. 7 digital inputs (controllable from the receiver) would have been a nice feature.

Another interesting thing is the cs493263-cd is capable of DTS (there's even a DTS logo on the chip). But I'm not sure what's required to get this to work.

In Pro Logic mode, there's a noticeable distortion in the center and surround speakers (with or without the hacks, or even with different speakers). It's almost like an overdriven pre-stage amplifier, but it's always there even when the level is low. It's most noticeable when someone sings (female voice). "Phantom" mode gets rid of the center distortion, but the surround speakers still have it. Note this problem is not present (or at least not noticeable) in Dolby Digital mode. The distortion sounds a little like clipping or half-wave buzzing. Evidently many NSX-DSxx units (and even some other models) have this problem. This is by far the most troublesome and annoying.

If anyone knows of a fix for this or hears the same distortion on their unit, let me know.

My unit fails to read some cdr's, and skips on lightly scratched cd's. Aiwa is infamous for their low quality laser pickups and carousel mechanisms. The NSX-DSxx units have plastic dust covers that activate when no disc is present. Older Aiwas do no not have this. Hopefully this wont cause more problems.

As shipped, the tape azimuth was way off (both decks).

Still works, knock on wood. Some older Aiwa mini stereos had unreliable display's, possibly attributed to heat. The NSX-DSxx units are fan cooled (look at the bottom of your unit, if you didn't know).

Stands for (Dynamic Integrated Neo Amplifier). When I read this I thought one thing: single-chip amplifier. I was wrong, the NSX-DSxx units use discreet components (transistors), 15 of them, all attached to a massive heat sink and cooled by a fan. Don’t know where the "IN" part of DINA is on my unit.

bchafy@ccs.neu.edu