Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems 861 and MRC will not work - SNL too low

None of the 3 above questions are relevent to MRC. I use a cheap 30' Belden RG-6 coax cable with cheap RCA F-Conn terminations.

The more significant question would be is it 75ohm.



Pure and simple...MRC has problems. M needs to step up and address all the issues. It should work the 1st, 2nd, and each subsequent time without a problem -- no matter who's running it and their level of experience.

Which would you rather have?

Let's say you have a bad woofer in one speaker?

Would you want MRC to succeed and do the best it can or fail forcing you to dig deeper and find the problem woofer?

The checks are thorough and usually points at a problem.

I have used systems that a bad woofer would pass, Meridian's would not.

Reporting offsets does help eliminate possible problems. If they were very lopsided (between left and rights) it could indicate a bad woofer that was compensated for by calibration that won't pass MRC. His offsets look great. Actually almost too good to be true.

I'm not saying MRC is perfect and I would love to see a V2 of it. But this phase (Measurement) is fairly easy to get through. Unless something is broken or out of whack.

Let's see what he comes back with after skipping some speakers.

George & All - thanks...

was away for almost a week and just back today... have tried everything... force skipping speakers failed every time (SNR to low)... it did not matter if i tried fr, fl, ctr, rr or rl... interestingly, the SNR was consistent for almost every speaker (8k fr, fl) and (5.2k c, rr, rl) at 14db...

was then concerned that maybe all of my Meridian speakers were bad so re-calibrated entire system with set of b&w nautilus 905 as rear speakers... front, right and center still failed (i know obviously) but when skipped to rr and rl they also failed because SNR too low... any ideas on what to try next?

on room layout details.. approx 20 by 30 with 10 foot ceilings.. rf and lf (the 8ks) are approx 18 feet from listening area... center (5.2k) is approx 15 feet from listening area... rr and rl (5.2ks and also tried with B&W 905) approx 6 feet... shag carpet (approx .5inch thick) and bare walls...

In addition, purchased yet another sound pressure meter from radio shack and a new cable (25 ft basic monster audio cable)....

thanks for all the help...

Wow 14db that's really low. Something is very wrong.

Running out of ideas.

I'm wondering if you have some sort of noise source somewhere or a bad input.

Try this.

Plug the Mic in. Select that as the Source. And talk into it.

Bring volume up gradually. just below feedback level.

Does it sound clear? Any Hum? Any static?
Compare it to the opposite channel (L vs R).

Watch out for feed back when your doing this!!
You can blow a tweeter in a blink.

Do you have an analog source you can try on that input?

Did you read the wiki page there are other things to try there.

What range is the meter reading during the pink noise from MRC? I believe it should be around 87 (i.e. on the 90 scale needle should be just left of center). I'll try to double check if nobody else can confirm.

wints1,

I just double checked what the meter reads during measurement and it should read around 87. Knowing what you get on this will help determine if the problem is before the Mic (output of speakers, room) or after it (Mic, Mic-Cable, Input sensitivity, input ADC).

I use a G68 not a 861 so this might not be applicable, but your problem is very similar to what I experienced a few months ago so I’ll share what I found anyway.

After changing power amp MRC started failing, blaming the SNL. When running pink noise the G68 turns the volume way up, I believe to 80. With my old amp that was just acceptable, but the new one had a lot more gain so the actual sound level in the room passed 115 dB!! At this volume the rooms resonating frequencies generated a lot of unwanted noise making measurements impossible.

I didn’t find an option to change the volume setting, so instead I turned the individual gain on the speakers way down. My front left being the “loudest” was set to -12 dB, and the others adjusted accordingly to get a matching SPL response from all channels. This altered my comfortable listening volume from 45 to 65, but most importantly MRC hasn’t failed since.

As mentioned above I don’t know if this applies to your system, but could be worth a try.

Andy's room is now fully calibrated and sounds amazing. This is yet another case in point where M has too enable their end-users (if the end-user desires) with an internal calibration kit or find some other kit to rebadge as their own that's more robust than the POS RS meter.

Least it be said that there were several challenging factors to enabling MRC.

So are you saying it was just the RS MIC and all problems solved or there were other challenges that you're gonna keep secret?

There were several factors that played into it, but none specifically that you can say it was this or it was that and will help someone with their system. It's more a matter that if you're having problems, you need to have someone qualified look at your system and solve the problems. In this case, I was stumped at one point and had to call M America for help (which wasn't much help at all) and I ended up figuring it out shortly afterward.

Bottom line, go back to the basics and make sure your FW is up to date, you're RS meter has a fresh battery (I don't use one and have my own set up that has never failed a MRC), and ensure that your sensitivity setting is correct. All that said, nothing beats experience.

BTW, the system generated decay was 626ms...but of course that was tweaked for solid, tight bass, smooth mid-bass and a nice shelving curve to roll off the upper dBs.

I've been burned helping someone once that had a whole mish mash of firmware revs. I'll add that to the Wiki for trouble shooting.

For the record the RS Meter has never failed me but I can't say it's producing optimal results compared to other Mic setups. I just did a quick run the other night and got 49-50db S/N on all my speakers.

That's sound advice, but, feels very much like what was being repeatedly recommended originally. Clearly sometimes one needs a helping hand.

FWIW - my RS meter works fine, has a good battery and I always re-check the weighting and sensitivity settings. SPL is 45-50 at Vol=87 during MRC.