Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Restaurant at the End of Universe Hitchhikers - Meridian Equipment AC12 alternative

Hi all,

As a musically inclined electronic engineer, I've been considering building my own version of the AC12 for some time now (in fact, even before M released the AC12!) and was wondering if other people would also be interested in a cheaper (and correctly wired ) alternative to the AC12?

If so, what features would you like to see (or not) in an AC12 alternative product?

• An active system for longer cable runs?
• Drop the RS232 connector, given that it's rarely used in day-to-day situations?
• What about DIN comms? a) Use only BNCs on the product and bundle BNC-DIN adapter cables, b) Include DIN and BNC connectors on the product or c) Exclude DINs completely?
• Could one get away with just a single comms (BNC) connector on the product, that is switchable between Master and Slave?
• Your suggestions here!

The cheapest option would be a passive product with a single BNC comms connector that can be switched between Master and Slave. This would be fine for my purposes but may be too limiting for other people with more complex systems, so I'm keen to hear your thoughts.

If a specification can be agreed upon then I'll produce a prototype for feedback and review by some esteemed members.

There may also be other solutions in the pipeline too. I have a feeling that someone else may have done some work already on a version. Plus off the shelf solutions that can possibly achieve this for about �15 per 2 channel pair and a bit of soldering XLR to RJ45 punch downs.

tell me more about this �15 solutions please

Do we think that those little ICs on the PCB of the AC12 has low jitter properties?

That exact question probably caused me to hum and haw for six months, before deciding to upgrade to the 861v6

Adding in an extra Speakerlink In and SPDIF Out Interfaces (to get the AC12's to work) is just introducing 2 extra stages of proven Jitter creation (as Meridian have said so frequently in the past

All we can hope for is that the internal components in these AC12's are at least up to the level of those used in the 861.

I'd hate to think that any improvements offered by the V6 would be negated by these little totally unnecessary boxes

Jaco

Untested but... XLR to Phono converter (ie Maplin N27GB or N64FL) then XLR plug or socket to suit wired via CAT5e/6 cable [shielded preferred but probably unnecessary] to RJ45 plug or socket+patch lead wired as XLR pin 1 (ground) to RJ45 pins 2+5 (orange+blue/white) [+shield if necessary], XLR pin 2 (AES+) to RJ45 pin 7 (brown/white), XLR pin 3 (AES-) to RJ45 pin 8 (brown) - colours as per EIC/TIA-B as commonly found on comms sockets.

Should be bi-directional passive device, but untested and unproven. At own risk etc etc. Everything depends if XLR/phono unbalanced output works or a true balanced connection is actually needed. This is audio only so will go behind processor to convert RJ45 speakerlink into existing S/M lead audio for legacy speakers so can use existing comms.

Total cost, less than �15 if you use RJ45 crimped plug and a bit of time to solder 3 pins/4 wires [+shield], slightly more if you go RJ45 socket/patch cable. Even better would be to take an existing 0.5m patch cable (STP) and cut in two, then you have two leads made up and only need to solder on to XLR plug/socket. You will need to know if patch cable is wired EIC/TIA-B or less common EIC-TIA-A as colours will differ - check colour of pin 1 - if its orange its "B", if its green its "A", if its brown you are looking at the wrong end! If pin 8 is blue (actually blue/white but it will probably be too small to see the white) then its a crossover cable - you want a patch cable which is all pins coloured same at each end.

To do it properly would require a small PCB to be made in which case, comms and RS232 could also be added and the XLR balanced/unbalanced circuit replicated to create a small neat box with three or four RJ45-speakerlink in / phono+comms out. In which case, t42 or someone else's unit may be a more professional alternative.

Great idea.

Actually I don't think that the Maplin adaptor will be a suitable prototype/cheap solution as it is not a true balanced/unbalanced converter so its still unbalanced over 3 core. May or may not be a problem over the short distance needed if unit placed behind processor. I don't know as there seems to be different ways of doing AES<->SPDIF of which AES->SPDIF is simplest but its all down to what voltages are used. Some of the Neutrik adaptors may be better as they are transformer based and still relatively inexpensive at about �40 giving a total solution at under �50 per 2 channel.

Alternatively it may be relatively easy to convert balanced/unbalanced using a component video balun such as this which if sympathetically wired, may do the RJ45/phono all in one and just need a suitably wired CAT6 cable - you would lose the 3 unused connections, effectively using only one of the three component video channels to transmit the signal. Worth a call to madnat to see how it is wired internally - they make some of their own kit so may be possible to get a custom job.

so basicly the info from the other thread on the pin layout on the speakerlink.

I thought we needed to convert the balanced to non balanced for the audio. Is a simple XLR to phone connector providing that ?
The Comms seems straight foreward.

I will wait for a ready box i guess.

Most likely it is using one twisted pair per connection.

Absolutely. All the information is from the previous threads although I added cat cabling colours.

It all seems pretty straight forward and surely must be possible using existing relatively inexpensive off the shelf components such as the Neutrik adaptor which looks better than Maplin (also Neutrik made iirc) which offers true balanced to unbalanced conversion using an isolating transformer albeit at a slightly higher price - around �50 rather than original �15.

T42 Nobody else seems to have replied to you really. I'm in, what I feel, is probably a very common position. My current Meridian kit is all significantly pre-SL. If I ever wanted (could afford) to upgrade I have to factor in SL conversion halfway through the process or spend twice as much (watch my lips, it ain't gonna happen). A decent priced SL to 5M/5S (or vice-versa) solution would be a great idea. In relation to your specifics

How long before you need active?
Agree if there's an RS232 on the back of each DSP it doesn't need repetition for me.
My older DSPs are DIN comms, I feel I'm your target audience in a way but I'm Mk1 (albeit 24/96) DSP5k. if every newer DSP has BNC comms you're probably talking sense.
See above, but I do see the sense in switchable master/slave.

Does that help?

Richard