Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Streaming LAN isolator anyone?

I use shielded twisted pair (STP) cat6 cable from my 861v6 to my various non-SL DSP speakers in my HT and am very satisfied. In my lounge I use Meridian SpeakerLink cable between 818v2 and 8K's.

Robert's excellent Revivers allowed me to enjoy the sublime sound of the 818v2 with the old style 8K's, tiding me over until the upgrade was offered! Prior to the SL cable, I was using plain ole cat5 cabling, I thought there was a slight improvement using the M SL cable, it might have been a bias (in my head). In the end, does it matter that much?

IMHO , speakers > processor > streamer > cabling

this is historically where I have gotten the most out of my money (left hand side = higher "bang for the buck")

Switching from MP3 to FLAC for my streaming made a big difference a long time ago ... I assume you are beyond that :-)

Congratulations on getting your MC200 to work with your DSP speakers ... Enjoy the music!

Let's just be clear here, there won't be any bit errors by noise over any Ethernet cable, unless it's broken. TCP/IP takes care of that.

What this company tries to say is that the cable transmits other noise over the wire and this has a detrimental effect on the system.

Ferrite chokes reduces common mode noise at high frequencies.
They all have a frequency range. Looping the cable through a toroid increases the effect.
Note the "reflected back" portion.

Ferrite Chokes, Toroids, etc.

I don't use them ...

100 Ohms 1:1 Isolation transformers does not care if you "send" Speakerlink/MMHR or Ethernet on them. They care about the datarate but anything with GbitE is "good enough". They will electrically isolate voltages on every pin.

The Giso GB is a LAN/AES/EBU isolator for Audio recording uses. They also support running AES/EBU signals due to the superiority and convenience of the RJ45 interface compared to XLR cabling (AES/EBU). Rings any bells?

GISO GB LAN/AES/EBU isolation for studio use

You have simliar application in the Meridian Prime USB isolator ports on Prime headphone amplifier. Industrial application for USB looks like this:

USB Isolator for industrial use

Edit: Some discussion on jplay (PC based ...about using LAN isolators for streaming)

Are you sure the 'GISO GB LAN/AES/EBU isolation for studio use' link was correct - that page stated you cannot use it for AES/EBU without adapters.

'GISO can also be used for AES/EBU signals using suitable adapter cables'

This actually means it's less convenient than XLR - since you'd need 1+1/4 unit to actually isolate the SpeakerLink signals.

You can't feed in the SpeakerLink signals blind and assume it works (if it does it's not actually doing anything - especially if the DC power from the SpeakerLink makes it's way through) and having RS232 RX+TX going through one transformer would not achieve much.

To isolate SpeakerLink - surely you need 5 transformers? (5 pairs of wires - that isolator only does 4 pairs)

1 TX - SpeakerLink data (AES/EBU) +/- (no ground reference needed)
1 TX - RS232 Transmit + ground
1 TX - RS232 Receive + ground
1 TX - Master Comms + ground
1 TX - Slave Comms + ground

(Someone please correct me if I'm wrong - yes I know you could probably leave one set of signals out if you don't want to call it SpeakerLink anymore - also - how does the DC power-over-SpeakerLink work?)

Since some people believe changing the digital interconnect changes the sound, surely throwing in a bunch of adapter cables to adapt from RJ45 SpeakerLink to RJ45 wired-for-lan, the transformers and another bunch of adapters would also degrade it?

I've left out any mention of the frequencies / voltage levels / differing impedances / the other sciency words etc... - and just gone for the physical issues.

At least with older Allen-Bradley PLC's, the 24V power line on the RJ45 serial ports tends to educate people very quickly the difference between an RJ45 socket and a LAN connector.

Matt.

No, you don't need adaptors for SpeakerLink for sending or receiving AES/EBU signals.

Adaptors are needed when you have older gear with XLR ports and want to send AES/EBU over RJ45 connectors instead.

Since Meridian in their wisdom already send AES/EBU over cat5e/cat6/cat7 cables both 2ch SpeakerLink and 8ch MMHR no adapter is needed.

????

The link you supplied to the 'GISO GB LAN/AES/EBU isolation for studio use' states it can be used for either LAN usage (that's how the internal transformers would be wired for) or with adapters to use the transformers for AES/EBU.

The adapters are required since the isolator should be designed (internally connected) for LAN usage (i.e. 1000Base-T) and you are trying to use it for something else.

The isolator is for LAN use - the isolator has RJ45 sockets - with adapters to get the signals across the transformer winding you can use it for other things.

SpeakerLink also uses RJ45 BUT:
SpeakerLink is not carrying the same signals as a LAN cable (let alone on the same pins).
SpeakerLink is NOT just AES/EBU (actually it isn't AES/EBU).

SpeakerLink is:

- DC Power
- Meridian Digital Audio - MHR or SPDIF over 'AES/EBU type' - -- Balanced connection
- Meridian Master Comms
- Meridian Slave Comms
- RS232 Transmit
- RS232 Receive
Not including power there is the equivalent of 5 pairs of signals (SpeakerLink is sharing grounds between Meridian Comms / RS232 - hence only 8 wires/pins instead of 10.)

A transformer works with coils - i.e. pairs of signals - how does 5 pairs go through 4 transformers?

Look at the pinouts in the SpeakerLink used as Digital Out (XLR or SPDIF) thread.

How would sending RS232 RX + TX into the same transformer work?

If it actually works - surely that means it's not actually isolating?

If you only want Digital Audio - that isolator might work - assuming you cut out the other pins to avoid the chance of wrecking the kit at either end (most people using SpeakerLink want the comms and also don't treat the electronics at either end as disposable for experimentation).

Wiring inductors (transformer coils) across comms signals might be interesting, but take the example of a spark plug - do you really want to risk your speakers / source having the comms interface / RS232 interface fried? (Whether through back-EMF, connecting the DC power across a coil, etc...)

If you are trying to isolate SpeakerLink properly - you would need opto-isolators for the RS232 to make sure the levels end up correct - and possibly the same for Meridian Comms (but I've not looked at the Comms signal format).

Looking around at what's got RJ45 within reach of me that is not wired the same as a LAN port (and will possibly give expensive results if mistaken for one):

Meridian SpeakerLink - RJ45
Allen Bradley Powermonitor 3000 display - RJ45
Allen Bradley DH485 - RJ45
Allen Bradley ControlNet - RJ45
Cisco Console port RS232 - RJ45
Red Lion Data Station RS485 - RJ45

RJ45 doesn't mean LAN signals.

I would appreciate corrections to any of this.

Without Meridian's endorsement - personally I would not risk any kit by connecting an isolator designed and wired for LAN usage. (inductors can give back more volts than goes in and RS232 is meant to use specific DC levels).

If it works - RS232 probably won't (don't the newer speakers make use of that?)

It could turn out to be an expensive mistake.

Matt.

The pairs on MMHR and Speakerlink are wired exactly the same as cat5e/6/7 ethernet. Otherwise you couldn't just take any straight cat5e/6/7 ethernet cable and expect it to transmit Speakerlink or MMHR.

The physical 100 ohm layer is the same. That is why you can use any conforming cable in your household.

RJ45 Pin 1 -> RJ45 Pin 1
RJ45 Pin 2 -> RJ45 Pin 2
RJ45 Pin 3 -> RJ45 Pin 3
RJ45 Pin 4 -> RJ45 Pin 4
RJ45 Pin 5 -> RJ45 Pin 5
RJ45 Pin 6 -> RJ45 Pin 6
RJ45 Pin 7 -> RJ45 Pin 7
RJ45 Pin 8 -> RJ45 Pin 8

Straight through cable.

Of course the cable would work - even if you rearrange the pairing (for short distances / low frequencies / etc...)

Trying to justify the use of a device on the basis of 'you can use the same cable' is not a good idea - see the other things I listed with RJ45 - all of which I can use the same cable for, but you do NOT want to mix them.

The isolation transformer(s) should not be considered as a passive device.

The posts I made were not about a straight through cable - the posts were made about an isolation transformer - and trying to shove 5 pairs of signals through 4 transformers.

Isolating RS232 (within the speakerlink wiring) should be done with an Opto-isolator - not a transformer (or does the Manufacturer claim it will work with RS232 (doesn't EBA control need this?) and I'm not sure about Meridian Comms?)

Once you start throwing transformers in, you no longer have a straight through cable. My posts were NOT about cabling but the signals going though it and only 1 of the 5 is the digital 'AES/EBU-ish'

Personally I can't afford to risk my Audio equipment on this sort of experimentation and I was concerned about leaving it unchallenged in case something expensive happened to someone - you are trying to isolate digital audio (that the isolator is compatible with) AND Meridian Comms AND RS232.

This is no longer at the swapping interconnects level but modifying the signal going through the interconnects (which would require detailed knowledge of the endpoints to evaluate - although the RS232 issue disqualifies the device from the start).

When I say 5 pairs of signals - don't immediately jump on that and say that a 4 pair cable works - the signals are SHARING the grounds for comms (M+RS232) - as soon as you throw a transformer in you loose the shared ground because of ISOLATION.

Somewhat frustrated at this point... Do you know what RS232 is?
This is NOT about cabling - this is about the suggestion to use an isolator designed for something else and why this is not a good idea.

Remember - only 1 / 5 of the signals is AES/EBU-ish.

Is there anyone else that can chip into this?

I'd want assurance from someone that the device:
Is compatible with Meridian Comms?
Is somehow capable of taking RS232 through a single transformer and ending up with separate Receive + Transmit at the correct DC levels (i.e. not actually working as a transformer)?
The DC resistance (NOT AC impedance) of a coil will either be high enough not to matter or not end up across the SpeakerLink power connection.

Is there anyone else that can chip into this? (could save someones system at some point).

Matt.

Why would you have any problem with Master and Slave comms? I don't see your reasoning at all here. It's not any more complex than wiring for DIN or BNC from SpeakerLink. If you keep your pin wiring straight, keeping the 100ohm impedance intact, checking voltage levels to see if anything is out of the ordinary. By using standard parts Meridian save cost. We are not talking about powering 50w devices over SpeakerLink with technology like PoE here.

Building/buying adapters/cables/whatnot have always been use at your own peril unless they have an M logo stamped on them.

I wouldn't have a problem with comms because I wouldn't put a transformer in the way

Again my posts were why the RJ45 LAN isolation transformer you linked to would be a bad idea for SpeakerLink - the whole thing, not just a cherry picked signal type out of the connector (without someone suitably qualified giving an OK)

RS232 relies on DC levels which would be taken out by the transformer.

RS232 relies on separate recieve and transmit datalines which would need separate transformers - unless I've missed the mention of a MAX250/MAX251 chipset in there (although that would need optoisolators in there as well)

An isolation transformer is not a pin-pin connector - the whole point is that they don't physically connect.

Is there an explanation for how the five different signals makes it through the (4 pair) isolator intact?

You've now mentioned comms - you still haven't addressed RS232.

This is no longer about wiring or 'adapters' - this is about modification of the signal - you are stripping DC levels and trying to run the equivalent of 5 pairs of signals through something designed for 4 - so it is significantly more complex than just wiring with wire. (Not sure why you'd mention measuring voltage levels - you'd need the transformer correctly loaded for that to be any use, and I've not yet seen a SpeakerLink simulator.)

Again (for the last time) this is referring to an isolation transformer that you linked to which takes 4 pairs on one side and giving 4 pairs on the other side being used on something that has effectively more than 4 signals.

Hopefully there's enough here to make someone think before risking an isolation transformer for SpeakerLink - I don't think I can contribute anymore without repeating the same statements over and over again, so I'm out of the 'but a LAN cable works so it must be the same' discussion. I've used this site extensively for research and I know how I'd feel if I'd wrecked my own kit following unconfirmed advice.

Matt

I have been looking at this little box all week, reading the reviews and trying to find a dealer, I would love to try it.
Apparently the ones on eBay and Amazon are fakes!!

Nick

Here is another manufacturer that have also better reviews- and have hires downloads too.