I just picked up a Rotel RDA-980 AC3 demodulator/decoder locally for $40. It's going to be fed by a Marantz LV520 (CLD-D504 clone, should arrive next week) and then on to a Marantz SR6011 AVR via 6 analog RCA cable. The AVR is also handling the comb/a-d/deinterlace/HDMI conversion, while the projector handles zoom for widescreen discs.

Curious if anyone else is using one, if there are any quirks in setup/operation, and if there's any known historical background of the design (clone, reference design, in-house, etc)?

Since the AVR will be handling bass management, time alignment, etc I assume I just set the all of the speaker size switches to large, time alignment to 0, and that's pretty much it? Since it only decodes AC3, I assume I'll still need to run Optical directly from the player to the AVR for digital stereo and DTS?

Any other thoughts/tips/tricks? It should be pretty simple, guess I'm just bored!

Thanks

Setup will be up to you and should be done right, I don't know enough on what you need to do with speakers etc.

You will need to connect both analog and digital so you can get both soundtracks depending on discs.
Some discs will have commentary and you will need to have that channel plugged in and select that on your amp.

Like I said, setup should be pretty simple/easy... guess I was just looking to talk about it while I wait to be able to pick it up on Monday

Anyone else have any info/feedback/knowledge of this demod/decoder?

That may not be the case so you'll want to check your AVR manual. Most (if not all) AV Receivers w/ a six channel input will bypass all the bass management circuitry so you'll have to set-up the Rotel accordingly.




You could still run optical into the Rotel and it will decode pro-logic out to the six channel output. However, you probably should go direct to the AVR if you want to hear DTS encoded LD's and CD's.

I'm pretty sure the SR6011 still applies full Audyssey XT32 calibration (including room correction, bass management, time/phase alignment, etc) to the 5.1/7.1 analog input... but I'll double check on that. If not, the RDA-980 may be a stop-gap until I can find a deal on a demod with AC3 output.

Yeah, if you’re using six line level inputs from a dedicated decoder nearly all signal processing will be bypassed, even Bass and Treble, as it should be. The levels are adjustable on the decoder usually and you’d never want to filter the sound or “manage the bass” because all the bass is already “managed” on its own dedicated channel. I have never used the decoder you’re getting but it looks like a monster so it should have all that.

The crux of any AC-3 decoder is that is turns AC-3 RF into either Dolby Digital 5.1 over SPDIF or TOSLINK or it converts all six channels to line level outputs. In these areas performance is identical with every unit. The only differences between different demodulators are the convenience features built on top of them like pass through, auto switching, etc, none of which exist on the most basic models. In the end when you put the disc in the sound will be the same unless some modern BS gets in the way.

"As it should be" is a pretty subjective thing. I'd rather have the benefits of Audyssey room correction + speaker-specific crossover points and take the hit of another A-D and D-A conversion in the process than maintain some illusion of purity. Still, after digging in, it looks like Audyssey and most other signal processing is indeed bypassed on the 7.1 input. It's not clear if simple speaker level adjustments are applied to the 7.1 input... my gut tells me they are but, if not, there's no way to adjust for it since the decoder doesn't have that capability. That would seem like a deal-breaker.

I'll need to see what I can find regarding crossover points on the RDA-980 since they're clearly fixed (small/large/off being the only options). My gut tells me they're stuck at 100hz... that's far from ideal, but probably passable and I might forgo the search for a stand-alone demod. If they're fixed at 80hz, I'd definitely stick with the Rotel. If they're fixed at 120hz, that would probably be a deal-breaker.

I'm not sure why the "quotations" regarding bass management... it's a pretty common industry term. The LFE channel isn't the only channel that contains low-frequency output... the other 5 channels are full-range and, in most surround systems, the speakers connected to those channels are decidedly NOT full-range. That's why bass management (in the form of crossover points set globally or, preferably, per speaker pair) is employed to send the low-end from those full-range channels on to a more capable subwoofer.

100hz is the x-over point on this processor when set to "small".

That's why I always loved my Sony, SDP-EP9ES. It has adjustable x-over for 40, 60, 80, 100, 120, and 150hz. Also, it does have a digital optical output so I simply use it now as just an RF Demodulator (six channel output not used).

Another option you have with the RDA-980 is figure out a way to add a digital output and turn it into an RF Demod / digital switcher. I think this model is sort of a clone of the Marantz, DP-870 and Harmon Kardon, ADP-303 which I know someone has modified for digital out.

Lastly, as a last resort, you could always look for an Outlaw Audio, ICBM-1 that does analog bass management for a six channel analog input. I use one right now for my SACD and DVD Audio players to correct the bass management for my odd array of speakers and it doesn't muddy the sound at all.

I think I can live with 100hz for now. I'm about to replace my B&W towers and center with Monoprice THX Ultra LCR in-walls and while 80hz would be ideal for those, 100hz will do. I'm innstalling a 2.35:1 screen which won't leave enough width on the screen wall for the tower speakers... the screen is Acousticly Transparent and the in-walls will go behind it. If I wasn't about to replace the B&Ws, I probably wouldn't consider be acceptable (currently have them crossed at 60hz, they're good down to 35hz)... but with the in-walls, it should be passable.

ICBM is a good thought, but for the going price (~$200, another full-size spot in the rack, and more cabling) I could just pickup a Yamaha demod (that would tuck away unseen in the back) and be done with it. I'll look into modding the Rotel, depending on the complexity involved... while also keeping an eye out for a deal on a stand-alone demod or a demod/decoder with passthrough (Sony, Onkyo).

I got the RDA-980 hooked up last night and it's working well. I tried a few different combinations of Small/Large settings and running my mains (B&W P6 towers) as large and center/surrounds as small seemed to sound the closest to how I have them crossed in my AVR.

My only other real complaint is that there is no IR for power on/off... it has an on/off switch on the front and I assume it's meant to be powered by a switched outlet on a Rotel AVR or Pre/Pro. Unfortunately, my modern AVR doesn't have a switched outlet so I'll either have to manually power it on at the switch or possibly add a smart plug and automate it through my Harmony. Also, the dynamic range toggle (max/normal/min) always reverts to normal after a power cycle... I wish it would remember max as my setting, but all pretty minor complaints given the price, condition, and local pickup.

So what DO modern AVRs have on the back of them? Just USB and HDMI? The newest thing in my home theater is a PS3 so I honestly don’t know.

For some reason, many of these processors only had manual on/off switches (all three of mine are designed this way). It never really bothered me since I have to always go up to my system when I load up a disc so I could just press the power button then. Also, I do have mine on the switched outlet of my AV Receiver but I still prefer to keep my processor off and not come on w/ the AV Receiver since I don't always need to use it (e.g.: my streaming device, DVD, and Blu ray players are connected directly to my AVR).





Not sure how the Rotel was designed but this could be a case of a back-up memory device not working anymore. I know my Sony, SDP-E800, needed a new super cap for back-up and replacing it fixed my issue of lost settings. The manual for the Rotel does not seem to indicate that settings reset after powering off so it's a possibility.

For the power on/off function, I think I will just pickup a smart plug and incorporate it with the Harmony activity for powering the LD player on/off, that way it only comes on with the LD player. An easier but likely costlier solution would be a power strip with a sensing master/slave outlet combo with the LD player on the master and the processor on the slave... I haven't looked at prices yet, but it's an option (a lot of AVS folks used them for AVR cooling prior to the prevalance of USB-powered fans).

I did consider the possibility of a failed memory backup... I may try to open it up and see if there's a coin battery or supercap but, as you said, I have to load the LD anyway, so I'm right there, plus I've I do forget it's not the end of the world.

A buddy of mine just got this entry-level Sony AVR since his previous one wouldn't pass HDR over HDMI to his new projector... and you're not that far off...



Granted, it's a pretty stripped-down entry-level AVR, but it does everything he needs it to. He has 4 HDMI sources and 1 analog source connected... a UHD player, an HD-DVD player, an AppleTV 4K, a PS4, and a modern turntable with line-level outputs (no phono pre-amp needed). He has pretty much zero technical capabilities, but he had it unboxed, hooked up, and calibrated in a matter of 20 minutes. There is something to be said for modern electronics

My AVR is pushing 4 years old now, but mid-level (MSRP ~$1199 when released), and still has most of the interconnects you would expect including HDMI/component/composite video in/out, optical/coax in, 7.1 analog in, 11.2ch analog pre-outs, Zone 2 HDMI-out and analog pre-outs, IR in, Marantz remote in/out, RS232, AM/FM antenna, ethernet)... the only thing they've really dropped completely is S-Video input. The equivalent 2019 model is identical.



That said, you can definitely spend $4k on a modern Pre/Pro and only get HDMI, a couple of Analog Audio inputs, and a few Optical/Coax inputs: