Signal loss issue

[TonyP]

The MP3 recorder (not player) (was) fed from the mono output via a splitter cable. The mono output is a XLR, so the cable went from an XLR connector and terminated in a 1/4" mono jack which was adapted to a 3.5mm stereo jack. It's possible that the mono/stereo adaptation here may have been problematic.

 

One of the oddities that hadn't completely clicked with me before was that, in general, the evening recordings were better than the morning ones. The reason is probably going to be that in the morning the crèche speakers are switched on, in the evening they're no need. It is possible that on occasions they've been left on inadvertently, I'm aware of one occasion of going to switch them on first thing on a Sunday morning to find they were already on, almost certainly from the previous Sunday morning. The implications of that for the other devices then connected to the mono output weren't appreciated at the time.

 

I use the word 'was' as today I've spent more time on it. The MP3 is now fed by a dedicated cable from the 1/4" stereo jack connection on the Aux 6 output, to a 3.5mm stereo jack (no adapter) at the recorder end, into the Line input of the recorder. After setting up the various Aux 6 levels to create a custom mix, the recorder levels look good.

 

So now we have the recorder, the loop, and the crèche all fed by dedicated desk outputs. It is possible, taking into account the helpful comments from the good folk here, that we may create a dedicated custom mix for the loop. This will depend on the views of our retired audiologist I mentioned earlier. She's told me that it'll probably be next week before she has time to consider the matter, she's got all the loop comments I've received so as and when we'll see what she says. I'll let you know in due course.

 

One thing I will say is that this whole experience has been a real eye opener. I'm reasonable technically minded (40+ years in the computer industry made me that), do the church website amongst other, and am regarded as the 'techo' (yuk!). But audio and mixing desks has been somewhat hit and miss and full of unknown terminology. This has helped me learn a tremendous amount about what a mixing desk does and so much more about its capabilities. And that wouldn't have been possible without the kind and helpful advice so freely given by people on this forum. Thank you. I'm well aware that, audio-wise, I'm still on baby food but hey, we all have to start from somewhere, and if I ever get to the Farley's Rusk stage I'll be happy.

 

(And being able to get in during the week to experiment and 'play' has been a real boon. Earlier this year I was elected a church warden so now have unencumbered access to the church, rather than in the past relying on the good will of someone to let me in and then staying or returning to lock up. It was all very inconvenient.)

[Simon Lewis]

...The MP3 is now fed by a dedicated cable from the 1/4" stereo jack connection on the Aux 6 output, to a 3.5mm stereo jack (no adapter) at the recorder end, into the Line input of the recorder. After setting up the various Aux 6 levels to create a custom mix, the recorder levels look good.

 

A quick look at the LX7's block diagram shows the aux output to be impedance balanced. This is a case of the popular, but incorrect terminology used to describe jack plugs causing a problem...

 

The aux is better decribed as being on a three pole jack wired for balanced operation (not a stereo jack). It's feeding a 3 pole miniature jack, probably wired for stereo left & right. If you have wiring the cable "pin to pin" then you'll probably find that the "ring" connection doesn't have signal on it. It needs wiring such that the tip connection at the desk goes to both tip and ring of the 3.5mm 3 pole jack at the MP3 recorder. Apologies if you have sorted this already!

 

Simon

[TonyP]

No Simon, I hadn't realised that. Thank you.

 

In reality the signal level display on the recorder shows the signal coming strongly on 1 channel only (can't recall whether left or right), exactly as expected from your comments. As it's only speech to be recorded, or in the very rare cases of more comprehensive recording, stereo is completely irrelevant.

 

When using Audacity to prepare the recordings for the web site afterwards I always create a new mono track out of the 'stereo' recording, in essence (forgive the perhaps loose terminology) I copy the 2 stereo tracks (one of which has no content) into a new mono track, thus the channel with content becomes the complete content of the new mono track. I then tidy that new track up.

 

All the desk inputs have the Pan setting to midway, there's no use of a stereo image.

[TonyP]

I thought it worth posting an update, including the comment of one of our congregation, a retired audiologist.

 

Her comments (edited from longer, and otherwise irrelevant, comments)

 

"a good speech signal is very important for anyone with a hearing loss whether a loop user or not. In any congregation (not just ours) there'll be people with mild hearing problems who don't need a hearing aid. Children also have difficulty coping with a poor speech signal as does anyone whose first language isn't English." In the context of fading down the music mikes - "Any open mic not being used is likely to lead to there being in effect more "reverberation" and reducing the speech to noise ratio.". Other verbal comments to me have essentially reinforced these views.

 

The latest state of play is that, according to a loop user on Sunday evening "The loop is brilliant, 120% better than a few weeks ago." I discussed with him about whether music should be included in the loop feed, he was adamant that it shouldn't. He said that when it was time for the hymns and he wanted to sing, he turned the loop off else he got,as he put it, his own feedback.

 

As a consequence in a couple of weeks, when we have time, we're going to put the loop on a custom mix, voice mikes only. That will allow us to put the crèche feed on the mono output and free the monitor headphone socket.

 

We've also realised the Ampetronics loop driver has a headphone socket on it (can't normally see it as it's partly hidden) so we can at least hear what that's getting.

 

So, all in all, a useful exercise that has helped our understanding and, far more important, we're now providing a much better service from the sound desk. As our retired audiologist put it, to misquote the end of Romans 10.14 " How shall they hear without someone preaching to them a good PA system?"

 

So, once again, many thanks to all here who've guided, advised, and helped us.

[Simon Lewis]

Tony,

 

Many thanks for bringing an update - it's helpful to know what happens after the advice is offered! If you want to read up a little more on the overall subject of intelligibility, this article is a good starting point.

 

Regards,

 

Simon Lewis

[TimmyP1955]

If you want vocals-only in the loop you don't need a special mix - just route the vocals to a subgroup, and feed that subgroup to the loop amp.