Audio cable management for new space

[kenomaerz]

I promised @Pakue95 to outline the options for our sound system, so here we go.

Some definitions: XLR,3.5mm Jack ("Aux") and chinch als are line signals. Chinch and 3.55mm are functionally identical, XLR is balanced trough an additional lead and voids humming and picking up interference. One XLR cable carries a MONO signal only, you need two for stereo. 99% of professional audio leads are XLR, 99% of home audio leads are Chinch or 3.5mm jack. All three can be converted to each other using adapter, but the XLR cable loses the benefit of balancing obviously.

Line signals differ from a speaker lines in that they carry a norm voltage. That signal needs to be amplified by an amplifier (duh) to power passive speakers, or the speaker itself in case of active speakers.

Option one: Central Amp, run speaker line to all speakers. Pro: Easy, Central control Con: Speakers need to have comparable power. limited by number of speaker outs of amp, one vol control for all speakers.

Option two: Central mixer, run line bus: This uses the advantage that most halfway decent active speakers have a pass-trough for their signal. So one can start laying down line cables from speaker to speaker, forming a bus. That bus can connect to active speakers, or to preamps that allow pass-trough. This has the benefit that all speakers can be separately adjusted. This is also what you will find in most professional installations.

Option 3: Central mixer with central star and line bus per room Pretty much the same, only that separate Line-Leads are run into each room. This allows to separate audio later and may be better from a cable management perspective. Be aware that splitting XLR requires amplification, and using separate signals requires separate outs.

Option 4: Digital Audio network Pro: Reduces required cable drastically, most powerful solution Con: Requires server to run on, complex requires decoders for each speaker bus to set-up, need to research software Finally, one could consider running audio over Ethernet. That allows the fanciest audio routing and stuff like adjusting volume when the doorbell rings. I have however not worked with such a system. We would have to see what the open source options are

I'll upload some schematics shortly.

Open discussions:

• Do we need stereo? I would argue no and down to mono, allows to just one XLR cable instead of two. There will be no proper stereo image in the hall anyway.
• Do we need a central mixer? That allows to put several signals on a single lead, e.g. Doorbell and audio. would be included in option 4 digitally
• Do we need XLR? We need to check what type of speakers we will be buying. If they don't support XLR, then XLR is mostly pointless, unless we use a powered adapter.

[kenomaerz]

PAM might be a solution for audio over Ethernet. Another might be using a capable media center like JRiver. I have to research how mixing signals would work there.

[kenomaerz]

After some more talks to Martin, this is what I currently believe to be the best setup. You can edit this document.

In short: Line signals are run from a central hub to the rooms. They are split at each room. The line for the bell is run to a dedicated speaker (or a two-way capable speaker). This speaker is installed in away that prevents tampering. The remaining lines signals are routed to a wall panel with one output for each line. The room can select the output source by plugging the speaker cable for the room into the corresponding slot.

The wall panel can take a few forms, among those are: Simple panel with the slots: Super cheap, selection by plugging in the speaker cable. Volume needs to be adjusted trough speakers.

Small mixer: Requires extra part. Selection happens at the mixer, allows local volume control.

This way, the bell is always heard. Requires no downmixing to the main signal, and selection of lines at the rooms. Works with standard parts. Very flexible. line signals can be slip using a y cable without problem, as long as the end consumer is not ancient.

Regarding the cable: I have no experience with cat 5. From what I see in professional products, 1 Ethernet STP Cat 5 can carry 4 lines over 75 meters. However, we will need adapters, and buying those is really expensive. If we have someone that can craft them, then fine. If we do this, I would actually suggest laying to cat 5 cables. This would increase cost by 15 Euros for the cables, and allows future expansion to more channels, stereo, or advanced stuff like an intercom.

[NitramLegov]

@Johannes09 This is the issue in which Keno outlined the possible solution for our audio management @kenomaerz Johannes is currently actively working on audio management. I would propose that you guys sit together and discuss further options :-) I´m also happy to participate in further discussions / maybe throw some money at the problem (if not super expensive :-D)