2ch sound concerns on 1068

[grit]

I'm running a Rotel RDV-1060 DVD to a Rotel RSP-1068 powered by a Rotel RMB-1075 playing on B&W 703s (fronts), 705s (rear), HTM7 (center), and ASW700 sub. The DVD player is connected by both analog RCA cables as well as digital coax.

When I listen to music, I select 2-channel bypass on the 1068 and get a wonderful sound, but there is no output to the subwoofer. When I select 2-channel stereo, the 1068 will allow me to send low end signals to the subwoofer, but the sound is less detailed than the 2-channel bypass mode. My understanding is this is because in 2-channel stereo, the 1068 converts the signal back to digital in order to process the bass signal, then back to analog. As for 2-channel digital (letting the 1068 decode the signal, skipping the DVD player), it's also my opinion that does not sound as detailed either.

So, how do I remedy this? I'm assuming I can't and that it is a limit of the electronics inside the 1068 (DACs maybe?). Does the 1098 have this same issue?

[mjb]

You want to drive your subwoofer in 2-ch bypass mode? If so, how should this 'extra' third channel be generated? Or have I misunderstood?

[Pez]

Personally I like pure 2 channel to have no sub involved, one of the reasons why I went with a 1068. If you want to run a sub and still use the bypass mode you could hook your sub with speaker level connections (if your sub has them). Otherwise you will only get sub output using the stereo mode.

[grit]

I guess what I was most concerned about was what was causing that change in sound quality and whether or not that change in sound quality would also be heard with the 1098.

It seems that if the 1068 decoded 2-channel CD music as well as the 1060 dvd player, I could just run the digital output to the 1068 and hear no difference between digital and 2-channel bypass. But, that is not the case. It's definitely more detailed in 2-channel bypass mode.

I would like the option of running the subwoofer in bypass mode, which I know is impossible without running the aforementioned speaker level connections, which I do not want to do. So, what I'm looking to do is find out WHY there is a change in sound quality so I can upgrade my equipment.

[mjb]

I would like the option of running the subwoofer in bypass mode, which I know is impossible without running the aforementioned speaker level connections, which I do not want to do. So, what I'm looking to do is find out WHY there is a change in sound quality so I can upgrade my equipment.

I'm not an expert, maybe someone will correct me, but the reason why the sound changes in bypass mode is because there is a minimal signal path, cutting out an a-to-d converter, several processor chips etc, and another d-to-a converter. Thats a lot of stuff! In by-pass mode the signal is simply attenuated (per volumn control), and not processed at all. This mode exists for sources that do not need processing, all that processing stuff is totally out of circuit for signal path purity. This is why, in by-pass mode, there can be no sub-woofer - the processor is not in circuit to generate the 'below so many hz' channel.

I don't really understand how you can be unhappy with something you say sounds better?

[maddog]

... When I listen to music, I select 2-channel bypass on the 1068 and get a wonderful sound, but there is no output to the subwoofer. When I select 2-channel stereo, the 1068 will allow me to send low end signals to the subwoofer, but the sound is less detailed than the 2-channel bypass mode...

Are you comparing 2 ch to 2.1 ch? If so, maybe that's why it sounds more detailed in bypass. Subwoofers have the potential to muddy the sound. You should compare 2 ch bypass to 2 ch via your pre for a more accurate comparison.

[Aussie Geoff]

Grit,

Bottom line the CD player's DACs are optimised for Cds, while the RSP 1068s DACs are more general purpose, needing to cope with all sorts of sampling frequencies and resolutions...

However, If you want to get that sub pumping, and use the digital connections without too much loss of quality you could follow a path I did and explore different types of digital cable. I went through a whol lot and found surprising differences and ended up with one of CatCables "secret" cables, their Silver Digital Magic - amazing...

However, after further research I found that a true CD player, like the RCD-1072 sounds even better than the DVD player at playing CDs - cleaner, sweeter, better soundstage etc... And here's the rub - this also applies through the digital connection... So I am now the proud owner of a RCD-1072 just for CDs and enjoy its amazing sound every day..

Geoff

[Cracking Oboe]

The DVD player is connected by both analog RCA cables as well as digital coax.

Hi Grit,

How are you switching from 2.1ch to 2ch bypass?
Do you use Video 1 on your RSP 1068 configured to recieve your coaxial digital input for 2.1 ch (a single Digital to Analogue conversion made in the RSP 1068), and the multi input (or the CD input) configured for the RCA input from your RDV 1060 for 2ch bypass (a single Digital to Analogue conversion made in the RDV 1060)?
Or, are you just using one input on your 1068 (in which case the coaxial digital signal would not be recieved by the pre/pro and it would be converting the Analogue signal to Digital and back to Analogue - bad).

I just want to try to understand. IMHO There is nothing wrong with your 1068, Bypass is supposed to sound better, which is why the bypass option is so desirable.

Cracking!

[grit]

Thanks all for the input.

When I put this system together, I was thinking 85% movies, 15% music. Having such a nice setup has made listening to music far more enjoyable than ever before, and I now spend more time doing that than watching movies. I have NO complaints/concerns whatsoever about how movies or television sounds. I'm just trying to optimize my music listening now.

To clarify - in analog mode, I'm running 2 analog RCA connectors from the 1060 (it has dedicated 2-channel analog outputs) to the CD input on the 1068. The 1068 either runs in 2-channel stereo mode, which allows the bass to be redirected (or also sent) to the subwoofer as well as the front 2 speakers (or 5ch stereo etc.). I can also select 2-channel bypass, which, as someone pointed out earlier, bypasses the processing functions of the 1068 (preventing any bass management).

I've also toyed with a single digital coax connection too, but for 2 channel stereo (eg, CDs), it never sounds as good as the analog, which I blame on the 1068 DACs (that someone said are not as finely tuned to music as the 1060s are). Thus, I was wondering if a 1098 processor would sound better for 2-channel stereo (not bypassed) due to having a hopefully better signal path.

The difference I hear between bypass mode and 2-channel stereo mode is more detail in the high end sounds. Stuff just sounds more real, pronounced, and alive in bypass mode. I LOVE the extra but subtle substance my subwoofer adds to music. And it seems, there is no good way to get both the detail I get in bypass mode AND the added substance from the subwoofer at the same time.


Aussie Geoff - thanks for bringing up the dedicated CD player. I was very curious if a dedicated CD player would sound better than the 1060. I'll give that route a try. I never considered changing my digital cable, but I'll try that too. I understand how cable can affect analog, but I thought digital either existed, or didnt, and cable quality would not come into play. Your input has raised my curiosity though.

[Kevin D]

In addition to the signal path problems, when adding a sub in you open up another can of worms. Sub volume, crossover points, sub placement, etc..

A lot of what might seem like less detail might be an un-optimized sub setup for music. This can muddy the sound which can colapse the whole soundstage.

You could turn the volume all the way down on the sub and then switch between bypass and regular stereo. If you still experience the same issues, you can rule sub-setup out.

Kevin D.

[gd]

I realize you said you did not want to go this route, but...

In light of everything that's been expressed here, I still think the best way to get the sound you seek is to add a sub to the fronts via speaker levels, and run them as 'large' as you continue to enjoy the better music SQ via bypass... your original sub can service 5.1 sources.

The additional sub for music need not be a big one, as music seldom dips below 30 Hz... I'm pretty sure you'd experience a greater difference this way than by trying a 1098 or other pre-pro.

The other more-expensive option is to consider extreme full-range speakers... which would likely prompt replacing the other speakers as well for voice-matching.

Seems you're very close to having what you want... I'd consider the sub.

[gianni]

Or, while this is a bit more complicated you could use an Outlaw ICBM or M&K BMC-Mini and use the multi-input to your 1068. Take the 2 outs from the 1060 to the bass manager and 3 outs from there (R/L/bass) to the 1068. I'm using the BMC with great results. (Or for movies use them all)

I know the 1056/1068 series has a few changes from the 1055/1066 which I'm more familiar with. With the older ones, If you use multi-input, you can still get bass from the sub. This is an analog pass thru but, the siganal going to the mains is split (or copied) and then used to generate a sub signal. Works pretty well with the exception that now you have your mains driven full range with no crossover - this led to the double bass issue. So, if you source does not do bass management for CD (one of my gripes w/ Rotel DVD players), and your mains are full range, this is not a great setup. With your 1068, I think this was changed.

Have you tried the multi rather than selecting bypass? This is what I use with my RCD-1072 and I use digital connections for movies. Downside is, you have to buy a bass mgr.

[grit]

I have tried turning the vol on the sub off to switch back & forth... still misssing the details, so it's not being caused by the sub. Thanks for the suggestion (I wish it'd worked out that way).

My concern about speaker level inputs is that i'll get 2 inputs when I switch to Dolby 5.1 surround for movies, which I do not want to do.

I've not tried the multi-channel input on the 1068, but my understanding is that you can do bass at a fixed 100 MHz, but I think it's a crossover. I don't want to cross them that hight because they sound really good lower than that. My main speakers are B&W 703s, and they do sound fine, I just want to be able to add something where they start to roll off in the low end.

Rotel's bass management works just fine, its just the dip in quality that I want to avoid.

[Kevin D]

You didn't happen to have any tone controls enabled for the front channels? That's also enabled on the processed stereo and a dip set on the treble could have an effect as well. Just something else to check.

Kevin D.