Will the Klipsch DD-5.1 "sound modes" produce simulated surround sound from a 2-channel CD player?

[marksalamon]

I only just became aware of the DD-5.1 preamp/processor and I'm interested in using it to create a "home concert hall," playing Classical Music compact discs from a standard, 2-channel CD player through up to six identical, full range, actively powered loudspeakers. Will the DD-5.1's sound modes (Hall, Theater, Stadium, Club and Church) provide a simulation of "ambient acoustics" through rear-left, rear-right (and possibly rear-center) speakers? If so, can anyone tell me how convincingly realistic these sound modes are for "serious" music listening? Thanks for your advice!

[Donald1800]

First, allow me to address the simulated surround sound capability of the DD5.1. Recorded delay, reverb and center channel are properly decoded when ProLogic is enabled. In nearly all recordings, this is very natural and pleasing. I have heard very few artificial artifacts.

There may be some recordings (or your personal taste) where you may want to use the 'space' of your choice (Club, Hall, Theater, Church) with up to 1 reverb. Use wisdom on the reverb selection as it is overbearing at 2 or above.

I hope this helps. If you have any other questions, I'll try to answer them.

[marksalamon]

Hello Donald, and thanks kindly for you response. As you can probably guess, I know very little about the Dolby sound-decoding technologies, and I had made the assumption that these worked only with program material that was already encoded with 5 or 6-channel information, such as DVDs or computer games, and would not supply center and rear-speaker sound from a 2-channel audio CD input. I'm glad to learn from you that the ProLogic system will realistically "decode" a standard stereo music CD into a multi-channel Home Theater System, because I have already heard from 3 different individuals that the various "venue modes" (concert hall, church, etc.) built into the Klipsch DD-5.1 would not provide convincing "ambient sound" when listening to Classical Music (my main form of entertainment.)

I first became interested in Classical Music "surround sound" with Dynaco's introduction, in the 1970s, of a "passive" multi-channel decoder, which, despite its simplicity and modest cost, produced surprisingly good results. I still own one of these decoders, originally designed to be installed between the power amplifier and the loudspeakers. But I have recently invested in "active" loudpeakers, the Paradigm Reference Active 40s, whose power amplifiers are sealed inside the speaker enclosures themselves so, I've been searching for a decoder like the Klipsch DD-5.1 that functions at the pre-amplifier stage in a music system. From your reply I've deduced that you've been listening to all types of music, with satisfying results, using the Klipsch DD-5.1 in a configuration like this. I haven't seen actual test specifications published for the Klipsch DD-5.1, but I've made the assumption that its technical performance is electronically accurate enough to be used in a "high end audiophile" music system (in addition to DVD viewing and gaming.) Have you found this to be the case? Thanks again for your reply.

[Donald1800]

You should understand that ProLogic only simulates by using normal recorded delay and reverb - it is no where near the same as true 5 channel recorded surround sound. It does accurately reproduce the delay and reverb, whereas normal stereo only simulates it through two speakers. As such, I personally prefer ProLogic with 2 channel stereo sources. As an aside, I have been told that ProLogic II actually creates true 5 channel from stereo sources. It is a shame that the DD5.1 uses Prologic instead of ProLogic II.

For most music, I generally use the 'field' that the music would normally be heard in, using a reverb of 0 or 1 depending on your taste. For an example, my Morman Tabernacle Christmas CD is played with the Church field with 1 reverb, and my Yanni Live at the Acropolis is played with Theater and 0 reverb. You will find what you like.

Other than not having ProLogic II, I have found the DD5.1 to have every feature I could need to optimize my PM5.1 sound system - including a 5 band ±10db equalizer which boosted the 15-20khz band and attenuated the 60hz resonance of the sub-woofer, resulting in a 29 - 20khz ±3db frequency response.

[marksalamon]

I appreciate all your information, which has encouraged me to place my name on the notification list for the (currently unavailable) DD-5.1 preamp/processor.

I've been able to locate the Dolby website

http://www.dolby.com/

which has been helpful in explaining the distinctions between the various surround formats that Dolby has developed. From the descriptions given on the site, it seems that the basic Dolby ProLogic decoding is very similar to the "passive" Dynaco system I mentioned earlier, because they both route L + R signal information to the front center channel (the Dolby site states specifically that the ProLogic circuitry attenuates this center signal by 3 dbl, since the combined signal would otherwise be too loud) and both the Dynaco and Dolby systems route a L - R differential signal to the surround channels, (through a filter that blocks frequencies below 100 Hz and above 7000 Hz to avoid confusing localization effects, though the Dynaco decoder does allow the listener the option of turning the filter on or off.) Dolby Prologic also adds a slight time-delay to the surround signal to further simulate sound that has reflected from the surfaces of the performance venue itself; the Dynaco decoder does not include this feature.

My one concern about Dobly's ProLogic decoding is the bandlimiting filter applied to the surround channels. I have bought four identical, full-range, excellent quality, "active" loudspeakers capable of reproducing music truthfully from 30 Hz to above 20,000 Hz, with the desire to benefit from their fidelity in all channels, front and surround, because I knew that my primary purpose for these audio components would be Classical Music listening (rather than TV viewing or gaming -- believe it or not, I don't yet own a DVD player, a television, or a desktop computer, though these are all gadgets I'm considering for eventual, future purchase.) I wonder if I wouldn't defeat the purpose of having acquired these fine loudspeakers by adding in a decoder like the Klipsch DD-5.1, whose Dolby ProLogic circuitry would eliminate the highs and lows the speakers can faithfully provide. (I'm a fan of Baroque organ music and, now that I've found speakers that can do justice to the lowest pedal-notes and the highest pipe-overtones -- essentially free of any distortion -- I'm a little reluctant to eliminate these portions of the audio spectrum!) I should probably also mention that all four of these active speakers have individual high frequency, low frequency and volume controls, so, I can already tailor their response to the characteristics of each particular recording, when needed, without truncating large segments of their full sonic range. Does the Klipsh DD-5.1 allow you to turn off the ProLogic bandlimiting filter, if you wish? If not, I might just find myself using only the "venue modes" on the device, or employing it fundamentally as a pre-amplifier (where, I've assumed, it would function quite well) between a SONY DVD / SACD player I'm considering to buy (which includes its own Dolby Digital/DTS 5.1 decoder) and the power amplifiers of my present speakers. I've honestly been enjoying this equipment "research project" I've embarked on, trying to learn as much as I can about these surround processors, and I'm grateful for all the "educational answers" I can find. Best regards...

[Donald1800]

The R+L center channel stripping in the DD5.1 decoder SHOULD be -3db down to compensate, but my test finds that the center channel is too forward by 3db - hence the -3db cut I plug in to the DD5.1 Bal C function. The R-L signal to the SL/RL speakers are almost un-noticable compared to the delay/reverb effects, although the filters can not be controlled. Since the delay/reverb signals contribute the major effect, upper/lower frequency loss through the filters is really not noticable. I still find ProLogic reproduction of 2 channel data preferable to just stereo, and warrants serious consideration. The REAL benefit of the DD5.1 will come when you get your DVD/TV set up with your new audio set-up. True full spectrum surround sound - ahh, bliss.

Since you will have the DD5.1, I would connect the future DVD player via OPTICAL cable, utilizing the DD5.1 as the only switched input 5.1 decoder source. This way, all room/system set-ups are consistent from source to source, and you still have the options for the 'field' effects.

In view of all this, I wouldn't worry right now about the filters. Just hook it all up and enjoy ALL the effects and note what you like. You won't believe the audio from the DVD movies in your home when you're through - it will be better than the movie theaters. I recently saw 'Lord of the Rings II', and I didn't care for the theater sound. It wasn't a smooth reproduction - peaks and valleys were very apparent.

[marksalamon]

Thanks once more for your clear advice, Donald. Now I just need to be patient until the DD-5.1 units become available again. While I'm waiting, I imagine I can keep myself busy making wish-lists of Classical CDs I'm interested in buying (I admit that I'm addicted to collecting those things; it's getting to the point where I have almost enough recordings to start my own FM music station, and I keep seeing additional performances I'd like to acquire, for one reason or another.) And if I stumble across a great bargain for the DVD player I've had in mind, that toy could easily become my gift from Santa this year (I seem to be a budding "home electronics geek" as well, though I've been trying to resist the temptation to spend large chunks of my retirement fund on gadgetry, even if this stuff is really excellent quality AND fun to play with. Next I can start bankrupting myself buying DVDs as well as audio CDs and SACDs. I suppose there are worse vices...) The expertise you've gained from working with these components is always welcome. Enjoy!