IC MPX replacement for tuner

MINER

Member
2012-10-15 8:58 pm
Beograd
I bought old ROTEL RT-550 tuner cheaply, and decided to try, and upgrade it a little :)
I already replaced the all electrolitic capacitors with MKP, and MKS ones, one op njm4558D with OPA2134, and those big capacitors in PSU bypassed with MKT ones. The sound difference now is like heaven and earth , and so i`m thinking to try, and replace some other parts :) ^__^
There is MPX decoder chip HA12003 16pin DIP but couldn`t find data on it, but found HA12016 which seems to be the newer version of the chip.

HA12016 HITACHI, HA12016 Datasheet
HA12016 pdf, HA12016 description, HA12016 datasheets, HA12016 view ::: ALLDATASHEET :::

But cann`t find out is it pin compatibile, and i hope it`s a drop in replacement.

Does ANYBODY know something about this ???

Grateful in advance :)
 
Swapping parts for different parts with slightly different characteristics is not an upgrade; for an upgrade you need to understand the circuit better than the original designer. However, the resultant change in sound will be regarded as an improvement by the person who has spent time and money doing it.

Don't touch the RF parts of the circuit. An 'audio-style upgrade' there may stop it working altogether.
 

MINER

Member
2012-10-15 8:58 pm
Beograd
Look at your circuit; HA12003 has 14 pins and HA12016 has 16. So, not a newer version at all.
Why replace a working FM Demultiplexer with an unknown?

You`r right..... I didnt count it right......



I`m thinking, because if it`s possible to replace it with same pin-out, pin-to-pin compatible IC with better characteristics, i could enhace the sound even further...
Service manual:
https://drive.google.com/open?id=0B-cAIsvj4ucqWDFjMWJqODJ6NDQ

Is there a better IC that i could put it instead of HA12003 ?

@DF96: I`m electronic engineer, so i do have some idea about RF part. Like i said, i already replaced/bypassed ALL electrolitic condesators(capacitors), and 99,999% shure that it`s better(that`s why i`m thinking of puting better MPX IC), and thinking what efect will have replacing the crapy resistors(at least in audio section) with better metal-film ones(probably not that big difference, as capacitors, but stil gets me thinking).
 
Swapping parts for different parts with slightly different characteristics is not an upgrade; for an upgrade you need to understand the circuit better than the original designer.
It is not hard to improve on 4558. It is a very primitive part. However faster lower noise op amps require some detail fiddling. What are you afraid of, we'll blow the $15 we paid for these trash boxes?
As far as psycho acoustics, the more piano tracks sound like the wood Steinway between the speakers, the closer the box is to reality.
 

paba

Member
2004-09-15 6:55 pm
Montreal
Hi
If you want improve the sound do this...
- detailed alignment
- match the 10.7 mhz ceramic filters for shape and center fequency and get some as wide as you can. (280's)
- measure and correct as needed the fm deemphasis so that it is exactly 75us or 50us depending where you live.
These 3 things you can measure and hear the improvements they generate and it wont be subtle.
Dont change the mpx chip. Each chip has its own circuit. No such thing as a drop in. If you really want to experiment then take the composite signal off board and build a new mpx circuit using a good mpx chip that you find.
Improve the power supply rails by reducing ripple and noise if you know how to do that.

Get good attenna as high as posssible or stronger signal with minimal multipath to enter your tuner to begin with, That will do wonders to the sound.

Cheers
Paul