Question Optical digital output, center speakers and Windows 10 ?

Sep 30, 2023
Hello everyone,

I'd like to ask this question because, despite my research, I haven't found a solution to my problem.

I have a Logitech 5.1 Digital kit connected to the digital audio input of my integrated Realtek sound card on a Windows PC.

I want to be able to listen to music in stereo on my front speakers (left, center, right). When I switch to stereo mode, I only get sound from the left and right speakers. To get sound from the center speaker, I must switch to ProLogic2 mode, but I don't like the processing applied by PL2, and I simply want the sound from the other speakers to also come from the center speaker.

Even though I've tried various methods, I'm quite inexperienced and haven't succeeded. I've tried changing the Realtek drivers using modified drivers, and I've also experimented with Voicemeter, Equalizer APO, and Peace. Nothing seems to work. Does anyone have a tip to share? Thanks in advance.

PS: I'd like to mention that I want to keep the digital optical output.

Logitech Z5500 specs :

Performance Specs

• Total RMS power: 500 Watts RMS

-Satellites: 313 watts RMS (2 x 61 W front, 2 x 61 W rear, 69 W center)

- Subwoofer: 187 watts

Total peak power: 1000 Watts

Maximum SPL:>115 dB

Frequency response: 33 Hz - 20 kHz Amplifier: Ultra-linear high-capacity analog

Input impedance: 8,000 ohms

Signal to Noise Ratio: >93.5 dB, typical 100

• Drivers:- Satellites: 3" polished aluminum phase plug drivers-Subwoofer: 10" high-excursion ported driver with 6th order bass reflex enclosure

Surround sound effects:

-Hardware decoding for Dolby Digital, DTS® and DTS® 96/24 soundtracks

-Dolby® Pro Logic II (Movie and Music modes)

-6 Channel Direct

- Stereo x2

- Stereo

Supported digital formats:- Dolby Digital-DTS® and DTS® 96/24

-PCM (uncompressed stereo): 44.1 kHz/16 bit through 96 kHz/24 bit

Source inputs:

-(1) Digital optical for DVD or CD players, PlayStation 2, XboxTM, or PC sound cards (requires optical cable, sold separately)

-(1) Digital coaxial for DVD or CD players or PC sound cards (requires coaxial cable, sold separately)

-(1) 6-channel direct (3 stereo-mini connectors) for 2, 4 or 6-channel PC sound cards OR- (3) stereo-mini connectors for 3 stereo analog audio sources, such as CD and DVD players, PlayStation 2, Xbox, or 2 channel PC sound cards (some devices may require stereo mini to dual RCA adapter, sold separately)

-(1) Analog stereo-mini (on side panel of control center) for portable CD, MP3, or MiniDisc players

*Requires Xbox™ Advanced AV Pack or Xbox™ High Definition AV Pack, sold separately
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As far as i can tell, what you want, can't be done if you want to use only S/PDIF digital output.

You want this:
in stereo on my front speakers (left, center, right).
Stereo is 2 channel, aka 2.0. If you have a subwoofer, then it's 2.1

Now, if you add center speaker, it would be 3.1 (with subwoofer). Whereby;
I must switch to ProLogic2 mode, but I don't like the processing applied by PL2
This processing is normal, since:
Many Dolby Digital decoders are equipped with downmixing to distribute encoded channels to speakers. This includes such functions as playing surround information through the front speakers if surround speakers are unavailable, and distributing the center channel to left and right if no center speaker is available. When outputting to separate equipment over a 2-channel connection, a Dolby Digital decoder can optionally encode the output using Dolby Surround to preserve surround information.

What you're really looking for, is your center speaker also acting as normal 2.0 stereo speaker, rather than additional channel in 3.1 setup. - That, AFAIK, can't be done if you only use S/PDIF digital output. Maybe there is some software out there that enables you to differentiate center speaker, whereby taking center speaker out from 3.1 setup, and using it as 2.0, alongside already existing 2.1. I don't know.
3.1 setup is very rare and not many use it. Usually it is either 2.0 or 2.1. 5.1 is more rare, 7.1 even more so. 9.1 is almost unheard of and 3.1 is unicorn in all of this.
Sep 30, 2023

First of all, thank you very much, Aecus, for your clear and precise response. I suspected that obtaining my 3.1 setup with the SPDIF in a software-based way would be very difficult, if not impossible. I found a Cabasse central speaker from 1999 with 80W power in the street (14 kg, hehe). That's why I'm racking my brain to integrate it into my Z5500 system.

So, I cheated a bit and managed to tinker with the connections. I set the Z5500 to Stereo x2 mode, connected the central speaker to "LEFT REAR," and had the Front Left+Rear Left speakers on "FRONT LEFT." Everything works well, even though my setup is a bit unconventional. I simply adjust the left/right volume to get the sound I like.

I have two more questions: Is the central connector on the Z5500 specific in terms of power, or does it deliver the same power as the other connectors? "Satellites: 313 watts RMS (2 x 61 W front, 2 x 61 W rear, 69 W center)"

Could connecting two speakers to the same connector have any negative effects on sound quality, apart from volume and power? Could it potentially damage my speakers?

Thanks again for everything!

Jonathan from Paris

PS: sorry for that very strange translation, my english is bad :(


Is the central connector on the Z5500 specific in terms of power, or does it deliver the same power as the other connectors? "Satellites: 313 watts RMS (2 x 61 W front, 2 x 61 W rear, 69 W center)"
You need to look your Z5500 manual, which should state the power rating of it's connectors. Usually, connectors on the AMP are capped near to the limit of expected speakers they are going to power + a bit headroom.

If no such info is seen from speakers manual, contact Logitech and ask them.

Could connecting two speakers to the same connector have any negative effects on sound quality, apart from volume and power?
You mean connecting 2 speakers into same outlet on the AMP, where usually 1 speaker should be connected?

If so, you can run into speaker impedance issues (measured in Ohms); whereby two speakers combined is more than AMP can handle on that channel (port) and that, can cause issues.
Not an audiophile myself, so, had to double-check my knowledge regarding it. Found this;
Assuming the speaker impedance is within the range for which the amplifier is rated, then there is no danger to the amplifier. If you turn up the volume too much and don't realize the amplifier is clipping, it's possible to burn the tweeters. This is because the speaker crossover network, the passive circuit that sends low frequencies to the woofers and high frequencies to the tweeters, will also send high frequency distortion caused by clipping to the tweeters. This failure mode is well known among audio engineers and technicians in the business. But if the amplifier is not clipping, then there is no problem with driving large speakers with small amplifiers.

Either look from Z5500 manual what the channels (ports) are rated for, Ohms wise, or ask Logitech.

Jonathan from Paris
Greetz from Estonia! :D


Old tube Amplifiers in the 50's derived a center channel from the left and right speakers on how you wired up speakers. I have my Vintage 1962 Tube Amplifier boxed up at the moment but it has it, recent move. Audiophile here. I also have in my old paperwork I saved copy of how it is done. In a box not yet unpacked.

If your interested the old Tube H&Hscott Amplifiers and the 1950's Mcintosh had this right in the rear of the amp. It was all done in the speaker wire level. As to how it was wired, not trying to sell you on a tube amp.
In the early 1990 Stereo Review wrote a story with full pictures an how to do it all on speaker level a full surround sound with a center + the rear channels all wired to the rear of the front right and left main speakers. In the chain going to rear channels you had to add a volume knob but it worked.

You could do it with any receiver or amplifier except a Carver Amplifier as the Magnetic Field Power supply is not wired like a conventional power supply. You also could not run Polk SDA's speakers and a Carver for that same reason.
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