I have a Yamaha APD-1, it was the most reasonably priced demodulator on ebay a while back.

It seems to work and sound great. Is there any point, down the road, in trying to find a "nicer" one.

I guess i'm asking if these were manufactured in tiers (good, better, best) or if it was such a niche product at the time that they pretty much were what they were.

Thanks!

In terms of sound quality, they should all be the same since the basic job is just converting one signal type to another.

The differences are really about features. Some models will have an additional S/PDIF input and provide the ability to have an auto switching option when playing between AC-3 and PCM sources. In addition, many of us just use a complete surround processor that has the AC3-RF input, multiple S/PDIF inputs, and an S/PDIF output that can then be mated to a more modern AV Receiver or Processor just like a stand-alone Demodulator (this latter option is in many ways a great way to get a cheap Demodulator since many don’t realize they can hook it up in this manner).

So if you are planning to get a new one, I’d say “why bother?”. They are now expensive for what they do and since you already have one you’re in a good place. Unless you want more than one .

Very cool! Is there a popular model that many people in the community here use for this purpose?

Members in the past have even said all of them use the exact same IC. More information here: Is any particular AC3 demodulator better than any other?

I saw a junk receiver at a thrift store that supported AC-3 RF. I regret not buying it and trying to make a homemade APD-1.

Yeah, they all have the same chip. Chip design was expensive back then and AC-3 RF only lasted like four or five years so there wasn’t any development. It’s more about having the one with the right outputs or pass throughs to work with whatever your system is. Some have DACs and six line level outputs, some switch, some are bare bones and do nothing but converting AC-3 RF to a Dolby Digital signal.

No doubt you have already read about my problem prone Sony, SDP-E800 so I would probably not recommend it (although I feel at the end I will get it fixed and it will be good for another 10+ years).

Anyway, I do own two others that have had no issues. A Sony, SDP-EP9ES and a Denon, AVD-2000. They are similar in every way to the E800 but I definitely feel they are better built. The EP9ES has some better features as well over the E800 (more flexible crossover is one of the better things) but that is not needed when used as an RF Demodulator. The AVD-2000, however, has one feature that I love quite a bit and that is the “Auto” AC-3RF Input that will sense for AC3 and PCM and switch inputs automatically (more of these processors should have had this feature but unfortunately do not).

In any case, the Denon appears to be the toughest one to find on eBay. Both Sony models are ubiquitous and you will see good deals on them here and there. They key is to be patient because every so often someone has it for sale on eBay and don’t realize the value of it so they price it low. Just make sure you try and find one in good condition that comes with a remote (don’t need one to use it but just nice to have just in case).

Also:



Julien

I've got the Kenwood DEM-9991D. It stopped working a few years back so I decided to replace it with a Yamaha Apd-1. I eventually got fed up of using the Yamaha because it had to be stepped down.

Decided to open up the kenwood to see if I could fix it. A lot of the caps were out of spec after testing. I replaced all the caps but it still didnt work. Probably because I didnt do the most basic thing. I then checked to see if there was any power from the DC converter and it was dead. I couldn't open it because of a security bit. I just replaced it with a 12v supply I had lying around.

So be weary when buying. All these bits of kit are +20 years old.

What do you mean "stepped down?" Thanks.

Electric.

100-120

Yeah rein-o is right. I live in the UK and mains power is 240v. The apd-1 that I bought requires stepping down to 120v. I got bored of lugging the step down converter out everytime I wanted to watch an ac3 film. Because I use it for other things it doesn't stay there permanently. Now my kenwood is working i dont need to buy a dedicated power converter for the Apd-1.

Makes my life easier.

I got curious today after hearing this on LDF, and I can confirm after looking through a bunch of service manuals that there are at least two ICs that were in use, both by Pioneer.

The Pioneer RFD-1 uses the PD4007A, and the Yamaha ADP-1 uses the PD4606A. Both of these are 100 pins, but the pinouts have been rearranged.

The Sony MOD-RF1 uses a "SN-PM4007A", which I suspect is a rebranded PD4007A.

The McIntosh MAC-3 uses a proprietary 20-pin chip labeled RF1.

I don’t think there ever was a true high end audiophile oriented RF demodulator. None of them have a linear power supply but some of them have good filtering (McIntosh, Meridian i.e). Clean power has direct effect to Spdif (coax, toslink) output with much lower jitter which in turn will result much less errors. On such a low bitrate lossy audio format, I doubt there would be an audible difference unless it’s an extremely revealing system (think $200k+)

When you say “fewer errors”. What is you experience with this in testing? Every digital audio connection I’ve closely monitored produces about one error an hour, utterly impossible for any human to detect, and I don’t own anything high end at all. Reducing it to an error every two hours isn’t going to do much IMO.

(Edited, please use the YouTube tags)

Try this video, he explains digital audio very well. As an electrical and computer engineer who has spent countless hours reading on this matter and listened to a number of equipment I can vouch for all his claims.