Inside an Alpine CDA-9886
I've had my Alpine for a couple years now, since it is well past its warranty period, now it's time to take it apart!
Once the top cover is removed with two screws, and the CD transport lifted (held down by 4 more screws) and this is what we see:
A good quality 4 layer board and tidy PCB layout separating the various blocks to prevent interference.
On the left side, there is the tuner module and audio sections. The big chip in the middle is the main processor. Right side are the various DC-DC converters for the CD transport and audio supplies. At the top of the pic, attached to the heatsink is a linear reg and power amplifier IC along with a fan. Bottom of the pic is the circuitry associated with the interface with the front panel.
Here is the electronic volume control IC (TDA7417) doing all the audio signal processing.
Custom Alpine processor:
Audio op amps:
I'm surprised to see what appear to be SMD film caps used for the power IC input DC blocking. Showing that this headunit was made with sound quality in mind:
I tested my headunit with a CD with 1kHz 0dB track to see at what level the pre-outs start to clip. I'm quite happy to see that even at the max volume, there is no clipping showing that the levels of the various stages in the headunit are set correctly and the whole CD dynamic range is used.
I always wanted to upgrade its internal op amps as that is the only thing left in my car audio signal chain that does not use high speed audio op amps but the only thing preventing me is that most commonly used audio op amps (OPA2132, OPA2604, AD823 etc) usually come in DIP or SOIC. The '9886 uses a couple in TSSOP-14 (quad) and another pair in SOIC-8 (dual)
Audio block in the pic below. Stock op amps are NJM4560 (dual, SOIC8) and NJM2060 (quad, TSSOP14):
Opportunity came when I read about the latest generation op amps from TI/Burr Brown. The OPA1642 (dual) and OPA1644 (quad) both comes in SOIC, MSOP and TSSOP packages. Exactly what I need! If I'm not mistaken, they are the descendants of the 2132 and 2604 op amps with better specs (I like the low distortion, low current consumption and rail to rail outputs!)
I ordered a few to use in my headunit. For the dual SOIC8 version, I got the OPA1642AID and for the quad version in TSSOP14: OPA1644AIPW
For soldering, I like to use the Hakko K-series tips. It allows me to heat up a wide area using the side and if I need a pointed tip, I use the sharp end. You can see in the pic I can easily heat up one side, lift it up then heat the other side to easily remove SMD chips.
And the stock op amps removed cleanly without torn pads:
New op amps on the left and stock op amps on the right.
New op amps installed and cleaned with IPA and cotton swabs. One thing I always see are those op amp upgrade mod sites and they reinstall everything but never bother to clean the boards. It looks very dirty and unprofessional IMO as well as the flux causing trouble in the future as it may become conductive when exposed to humidity.
Another is checking for op amp stability. Since upgraded op amps are much faster than the originals, there is the possibility that it will oscillate. I checked the output with a scope with no signal and a square wave to look for ringing, overshoot or other signs of instability and there is none indicating a successful op amp upgrade.
How does it sound? It definitely sounds better. I wouldn't bore you and babble with the usual audiophile terms but it is definitely better than the original op amps. I highly recommend this upgrade and hear for yourself.
Page updated and copyright R.Quan © 05 Mar 2012.