Sorry for the newbie questions, I finally got an AC-3 RF demodulator and wanted to listen to some AC-3 on my laserdiscs. Here's my setup

LD-S2 with AC-3 modification by Kurtis
Nakamichi DE-1 AC-3 RF Demodulator
attach coax cable from LD RF AC-3 out to Nakamichi AC-3 RF input
Nakamichi AC-3 digital output (coax) to the AC-3 input (digital coax) of my
Technics SH-AC300 Dolby Digital Surround sound processor (output to 5.1 speaker setup)

Unfortunately, I don't hear any AC-3 sound with this setup. Any tips? I can use standard RCA style cables for these RF connections right?

I've verified that the Technics processor works with my DTS laserdiscs and the optical cable output. Bad AC-3 demodulator or ac3 mod on the LD side? Any way to verify an AC3 output signal?

? first are you using an AC-3 disc.
you will only get the sound from that type of disc and you have to select the correct channel on the LD player.

IF your technics has an AC-3 already you don't need the namamichi since it will be a second unit of the same thing.

but IF your technics does not have AC-3 then you need to have the nakamichi connected like you have it.
you may have to select that input manualy on the technics??
my pioneer had 3 setting, auto, manual and off? i think.
or it may have been 2 setting, it's been 5 years since i had it.

but try that, see if there is a setting that you can pick and make sure the AC-3 disc is on the correct analog channel.

Yes, I'm using an AC-3 laserdisc to test, True Lies (AC-3 version not DTS). I thought you don't need to select analog channel R, because the player automatically outputs an AC-3 RF signal through the AC-3 RF port (again my player was modified with this output)

The Technics has an AC-3 digital input, but my understanding was you need to feed the AC-3 RF signal through an AC-3 demodulator to and then pass the demodulated digital signal into the processor (because the AC-3 input on the processor is for AC-3 digital)

and yes, I made sure I'm on the correct input on the processor (AC-3 digital input 2)

i don't know about modified players, mine has AC-3 already and was not added, it's been some time since i had AC-3
setup in my system but i would select the analog channel just to be safe, it might be an issue?????? i don't know.

also when i used my AC-3 demodulator to the pioneer receiver i used the RCA cable only, but it didn't have an AC-3 IN just Digital audio IN i think.

so if your techincs has AC-3 Digital i would try that without the nakamichi first, it just takes some time to figure it out with your gear.

it took me years to finally set mine up right.

What is your "5.1 speaker setup"?



That doesn't make any sense to me since the Technics SH-AC300 doesn't support DTS and has no digital pass through.



Most demodulators have a light that comes on only when there is an AC-3 sync, unfortunately yours doesn't. Without that feature I don't know of any way to verify.

Hook a DVD player up to the Technics SH-AC300. Does that produce sound?

Yeah, basically I think either my demodulator doesn't work on the AC-3 mod on the laserdisc has been damaged (which seems on since Kurtis does great work) I'm leaning towards the demodulator.

If the DVD player works then its an issue with the player or the demod. I would say its slightly more likely that the demod was bad but there is no way to tell unless you try another player or demod.

how many ac-3 discs do you have? could a rotted dadc pressing affect the ac-3 sync lock?

no

It could be the level of the AC-3 RF output - my EAD TheaterVision player, which is basically a Pioneer CLD-99, has a lower RF level than my MSB LS-1 AC-3 Prototype and Panasonic LX-900 that Duncan modified. My B&K AC-3 demodulator doesn't like the lower level and when playing an AC-3 disc on the EAD TheaterVision, I often get lots of AC-3 audio drop outs. The first AC-3 demodulator from Lexicon, made by MSB, had a switch for different AC-3 RF levels from different companies players.

My Sony SDP-EP9ES has no problems with any of my players AC-3 RF output, nor does my Yamaha DSP-A1 receiver.

Not natively, but large numbers of the Technics SH-AC300 were modified by MSB to add DTS decoding and digital pass through - which, incidentally, used the same board as the Millennium 2.4.6. DTS decoder which MSB also designed and made. The Marantz stand alone AC-3 decoder was also a unit that many users had MSB add DTS to.

Thanks for the responses. I'm pretty sure it's an issue with the laserdisc player or the demodulator. I'm probably going to end up buying a Yamaha DDP-1 (I just love the look of the system). Hopefully the Yamaha is pretty forgiving with possible low level AC-3 RF signals?

If you do turn out to have a problem with low level AC-3 RF signal, the Sony SDP-EP9ES is a superb decoder, even with low level RF signals, and offers direct pass through of DTS/PCM signals - if you use the 6 channel analog outs you can take advantage of its incredible Pro-Logic decoder which was also used in Sony's theatrical SDDS processor, and its signal processing modes which which really work well - I've never heard better, not even from Sony's other equipment. It also has analog pass through of 6 channel analog signals so it doesn't take up your 6 channel inputs on your receiver.

Also, the Lexicon I mentioned lets you adjust it for various player RF levels and MSB's engineering of it is superb.