Hi,

Two problems. Recently there has been a new sound install at church all is working fine but when we go to plug a laptop into the mixer we get big problems.

Firstly there is a massive screech when the jack plug is put into the laptop, current solution turn the level down on the unmanned mixer however this is inconvenient for the vicar on normal services, what would be a solution to this so that we could have the mixer level up without the massive screech when you plug in the laptop audio out cable? Obviously there will always be some clicking but this is fine but not a massive screech. DI box? What is the normal way of taking a laptop feed into a mixer? Both of our phone inputs are in use (rack mound 1u mixer) for a dvd player and CD/Tape Rack. Currently the laptop is feed by a very poor quality jack to XLR (just about to be replaced) cable into the stage box down the multi core then into one of the balanced mic inputs. Is this right or should I have a DI or should the laptop go into on of the phone line in, although the mic inputs are effetely line in.

The sound produced from the laptop is fine but when there is no sound being output there is a background hiss. Currently solution turn the mixer level done, but this again is inconvenient. First thing which would improve it is to replace the poor unscreened laptop to stage box cable, but I don’t this will fix it. The hiss is significantly but not completely reduced when the loop amp is turned off. The loop amp cable runs with the new multi core (currently what the laptop is being fed down). Is this an issue? If so should I run a dedicated screen cable away from the loop wire for the laptop feed? Also is the loop wire and multi core run being the same going to effect normal mic use as well? If so serious words need to be had with the install company. The multi core is Van Damme and fully screened so hopefully I won’t be a problem for balanced mic loads.

Any thoughts on the situation would be greatly appreciated…

First things first - shove the laptop through a DI if it is not being plugged in directly to the mixer. Long runs of cable which are unbalanced (like that from a laptop) suffer from electro-magnetic inductance. The DI turns it into a balanced line, which cancels said inductance... Basically, Laptop -> DI -> Stage box -> Multicore cable -> Mixer

99.9% of the time there will be some form of noise when you plug the plug into the laptop - a sort of crunching sound. However a screech is something I have never come across.


As an aside:

If you are using stereo, you may wish to make a dongle to split the signal into individual channels - they are fairly simple, the stereo plug has a sleeve, ring and tip, the tip is the left channel, ring is right.

The dongle should split the 3.5mm stereo headphone jack into two 5.25mm mono plugs. These are plugged into a DI for each channel... which makes things get expensive, but is something you may need to consider.

Ok I will DI the laptop. I any suggestions on a decent fairly low-cost DI box for this situation for use with the laptop only. Will a passive DI be suitable as there is now power supply easily available for an active one. Will a passive one work with good quality or is active the only way to go. The multi core is 30m in length. The laptop lead needs to be about 3m and the multi-core goes straight into the mixer. Will the short unbalanced audio cable be ok from the laptop to the DI if it is well screened?



Why would we need to split the audio into two different channels? Unless we loose the stereo by DIing the laptop into one out put? If we do loose the stereo we will have to use two DI channels as we really need stereo output from the laptop. So are there any good two channel DI for this purpose with my above comments about passive/active in mind?

Thanks and any comments on the loop system/multi-core setup would be greatly appreciated.

Hi,

With regard to the power supply issue for active DIs, if your mixer has phantom power on board, then this can be used to supply the necessary power to most DI boxes, providing all cables between the DI and the mixer are balanced correctly. If your mixer doesn't have phantom then 9V batteries are probably the solution.

A short cable (or cables) between the laptop and DI(s) should be fine, go for a decent quality one though, not bell wire!

If you need stereo from the laptop, you will need to proceed as mac suggests in the previous post as it is one channel to one DI box, I.e. one for left and another for right. Stereo signals are effectively 2 separate channels, hence the need for two DI boxes and for splitting the output of the laptop which I presume is on a single minijack connector?

You can get 2 channel DI boxes, a certain German manufacturer makes quite cheap ones which seem OK.

(Moderators - are we allowed to give makes/models?!) As long as you don't work for the manufacturer, of course. In Fact, even if you do, if it's justified in the context of the topic, go ahead - Bryson

Hope this helps

S

Ok, this will reduce the hiss and maybe even reduce the issue with the jack making above normal screeching sound rather than the normal clicking sound when inserted into the laptop audio out. Would a DI20 from Behringer do the job well or not? It is small two channel and can be powered by phantom power which are mixer has (although it is only 15vDC on our mixer not the normal 48v will this make a difference. I would have though not as the unit can run on a 9v battery). I know Behringer aren’t the best make but for a laptop feed surely this can cut it?

BTW our mixer is a TX8201 from Australian monitor. Website

I have just thought the loop cable will not affect the balanced devices on the multi-core at all, so it doesn’t matter that it runs with it. I personally wouldn’t have run them together anyway but that is what the install company did.

Thanks for you advice guys keep it coming,

EDIT: Our mixer spec is at the bottom of the linked page.

Not too sure you will reduce the hiss by using a DI box, onboard soundcards often chuck out a certain amount of noise regardless of what you connect them to.

Also, when you insert anything into a mixer where the faders/pots are turned up and the amplifiers are on, there will inevitably be some kind of pop, click or bang. If it is at all possible, the amps should be off until you have finished connecting source or at least have the levels down on the mixer.

In the specs for the TD8201 it says something about remote level control in the VCA control bit of the page - might be worth investigating if you could implement this if your mixer is not easily accesible for normal use. Ask the install company...

I see you guessed that I was referring to the DI20! The behringer spec for the unit states that it will run on phantom power of between 18-48V DC and your mixer only throws out 15V DC according to the specs. I guess you would have to check with Behringer tech support on that one to confirm whether it would still work at the slightly lower voltage. Or use 9V batteries and remember to turn it off when not in use!


S


PS - still curious about the screech, never come across that before in this situation!

Ok, well a DI box should reduce the hiss as it is mainly from the use of an unbalanced line as when the loop amp is off the hiss is dramatically reduced. Although PC card always produce a little bit of hiss it is nothing like this hiss. Unless you think otherwise I think it would be wise to make the line balanced regardless. As to the noise I agree with you the best thing to do it to have the amp muted and the remote main master control may be an option but radio mics all need to be used before and after the laptop’s use in the service off the same mixer. Adding an external main control would just add another possible thing to go wrong. The system is mainly being used by people who don’t know about sound.

This may be a stupid question but surely 15v DC from the phantom on the mixer is a higher voltage than the 9v DC from battery (quite obviously yes). So surely this would work, unless the battery is pushing far more current round than the equivalent phantom voltage?

Thanks,

I am just going off the specifications in the Behringer manual for the DI20!

Incidentally, when you don't have the laptop connected, is the hiss still present through the system and does it change when the loop amp is switched off?

Re: Screech
Does your laptop have an an integral mic ? If it does, and it's open, there's a chance you'll get instant feedback as soon as you plug in your speakers. Try muting the mic input in the Windows volume control mixer (you may also have a volume control mixer associated with your sound chip). As a final resort try inserting an unconnected 3.5mm plug into the mic input to switch out the integral mic.

Another thought: Unless I am mistaken, the laptop chassis is floating with reference to earth, possibly even when the psu is connected (although you could try reversing the figure-of-eight lead to the psu). As the TRS plug is pushed in the tip and ring will make with the sleeve and ring contacts, with unpredictable results.

Lots of people have had lots of problems with laptop sound. Have a trawl through previous posts...

Hi...

As previously mentioned, the squeals you're hearing could be feedback from the laptop's mic - check the settings in the mixer applet, make sure the mic input is turned down or muted.

They could also be coming in the form of feedback from the induction loop. I'm betting here that a long unbalanced connection is allowing the cable to become a nice long antenna for the induction loop - and that the laptop output is mixed into the induction loop along with everything else. The result? Horrible, horrible noises.

Solution? Use a DI (preferrably active) on the laptop output. If memory serves correctly, I think Behringer do a cheap active 2-channel DI that is useful for this kind of thing - somewhere around £30 last I saw. Again, it will draw phantom power from the mixing desk, but I think it can also run from a 9V PP3 cell at a push. There are others but that's the one I've seen most often.

DI'ing in this case probably won't solve the hiss, as most laptop sound devices are built for convenience rather than pure audio quality. In the long run, I'd be pushing for the use of a dedicated rack-mounted PC for church presentations and the like - at least you'd then get more choice in the kind of sound-card used, without spending over the odds for a USB or Cardbus audio device.

Hope this helps...

C.

I have previously experienced a half plugged in jack plug demodulating the loop signal at church, I guess the theory is as above, when one end is shorted it becomes an open loop aerial, and components in the preamp demodulate it.

Ok, I will see if I can get a DI20. This should do the job nicely, will it run of the 15vDC our mixer gives out even thought the spec calls for 18vDC minimum for the DI I presume it would be fine as it run of a 9v battery ok? (I posted this above but I really need to know before I order). If not I will have to by a external phantom power supply I seem to remember you can get them but preferably I would rather just use the 15vDC already available.

Anyone know about the DI20?


I still don't get how it will work ok at 9v but not at under 15v on a phantom power unless the current push is different, could anyone answer this for me?

Will this do for the feed from the laptop to the DI? It is two core so will carry stereo audio fine along with the common/ground given out by the laptop. It is screened as well and is only needed to be about 3m if that long. On end will be adapted into two mono jacks for the DI the other will go into our pc point box which has a audio input just with no cable going to it.

EDIT: Formatting corrected.

To make it neater when you split it to 2 jacks four core + screen would be a better cable. Or buy one, stereo minijack to double mono jack cables are easily found on the pages of maplins, adam hall etc

Either:
There is circuitry inside it to boost the voltage from the 9v PP3 battery up to whatever it requires internally.
This will be different to the circuitry used when being run from phantom power.

Or:
It uses two 9v batteries which gives 18v. (Not looked at the spec)

just a thought about the hiss: this is due to a poor noise to signal ratio from the laptop: not much you can do without getting a different sound card...

BUT: using a cheep gate, with the threshold set to the right level will happily cut out the hiss when no 'real' signal is being output...

It will most likely use either a voltage regulator to hold down the 48 volts or a transformer to up the 9V or down the 48V.

Looking at the fact that it can cope with variable voltage it will probably use a voltage regulator to hold down the 48V.

I could however be totally wrong.....

Just a thought... To get rid of the click as the jack is slid in, have you thought about something like this usb external audio device... of course this only works if you only have the same laptop used all the time (cos it will probably need drivers)

Two things...

1) A passive DI may provide better isolation between your laptop and the PA. If all else fails, I have had success with USB preamps for recording sermons and playing back material from PCs.

Otherwise, read the other posts on getting laptops and PAs to talk with each other.


2) No, the loop cable should not run alongside the multicore. Tell your installation company to do it properly;-) If you are an Anglican Church, let your Diocesan Technical Adviser know that the install was not carried out correctly.

The loop does not radiate RF, (as some posts suggest) but a varying magnetic field. This can be picked up by a variety of devices, and if there is noise / screeching present it is quite possible that you have an electromagnetic feedback loop. WHen you plug the laptop jack in, the usual click generates a pulse from the loop which is a high enough signal to leak into the input cabling and to then cause feedback. The loop's limiter will probably stop it running away, which is why it isn't continuous.

You need the laptop interface sorting out (why is it unshielded anyway?!) and the loop cable routing correctly.

Hope this helps!

Simon

Ok, well I think we have to go along the DI route anyway as we need to turn the signal into a balance feed. However for the connection noise problem maybe it would be worth installing a mute switch for the laptop feed in the pulpit. If so can any one recommend any small switches which would be suitable for cutting/muting the stereo output on the cable. Which is going to be installed into the current PC box. With regards to the gate could anyone suggest a cheap/decent model (links please)?

Thanks,

You still need to address the issue of the loop and multicore cable routing. You could still end up with various strange problems occuring.

Is the loop fed from a mixer aux output or from the line output of an integrated mixer amp?

Simon

The loop out put is from an aux output on either the amp or the graphic I am not sure which way it was done probably though from the graphic. I don't think the loop is causing too much problem though but I could be wrong.

However I need to know whether buying a DI box is the correct thing to do for the laptop output I would have thought so as at the moment it is an unbalanced feed running more than 30m and this needs to be balanced. Also is the idea of fitting a mute switch in the pulpit for the laptop feed a good idea? The switch would be inline with the cable coming out of the pc connection box already installed.

With regards to rerouting the multi-core this is impossible as there is no other route for it as it is a small church the loop cable also has to run along this route. Surely if the signals are balanced they shouldn’t be too greatly effected by it?

I will see if I can find a suitable mute switch and post it here.

Thanks,

I think, though not 100% sure, that for the mute switch any toggle switch should be fine. However, I'd set it up so that instead of simply breaking the line between laptop and input, it shorts the output to ground. This should help stop any clicks or pops when you mute it.

Gate wise, any cheap but decent compressor should have a gate function, e.g the Alesis 3630 or something from behringer. However, consider not a gate, but something called a "downward expander". A gate is either on or off, (you will notice it acting) however a downward expander is a more gradual fade-off.
Have you ensured that the gain structure of your system is correct? As in livesound, set the laptop as hot as practicable (without clipping or distorting anything though) and then the input may not need to be as high, so there is less preamp noise from the mixer.

David

The fundamental problem which has been brushed up to by a couple of contributors is that the speaker output on laptops are inherently noisy, and will probaly be unsuitable for your use, no matter how many DI boxes you use!

You need to use an external USB audio output device. Even the cheapest moeny can buy (which I think is an Eiderol something or other) is so much better than the PC speaker output will be.

This wont directly solve the balanced / unbalanced problem, unless the USB box is balanced out, which several of the more expensive models are. But it may be sufficiently better that you dont need to use a DI. I'm sure I'm not the only person on here who has shoved unbalanced signals down snakes with acceptable results...

Just had it from Ampetronic that it is considered to be "...asking for trouble..." to run a loop directly alongside an audio multicore. For all but short runs a gap of at least 250mm should be kept between the two, even with balanced lines. I would have words with your install company...

My church's loop system runs in the floor round the edges of the building and our multi runs straight down the middle, direct line from booth to stage. However as I have previously mentioned we have interference with electric guitars and when unplugging unbalanced devices.

Our install was poorly done, they got the multi and the loop right but we had to rewire the booth as unbalanced cables had been used when we specced a fully balanced system, and all the auxes were set up wrong. The speakers supplied and fitted were in the wrong place and too small for the music application specced (they were only designed for speech), and the lighting bars ended up 2m too low.

It seems to be the same situation as with schools there are a lot of con-men out there who profess to specialize in schools and churches, then give them a system poorly designed around their specs.

.....Rant over.....

It isn't going to help...! The quote from Ampetronic should highlight the issue, if you don't believe me

The way it's been set up is for everything that goes through the audio amp or graphic also goes through the loop. This is OK for simple installs, but as soon as it gets more complex (or has musical instruments etc.) you need to create a separate mix from a spare desk aux send.

Regarding laptop sound, can you borrow a couple of passive DIs to try out? The USB pre is going to cost more, but will give a better solution. However, I've used DIs with laptops before with reasonable success.


Simon

As others have said, a USB interface with balanced outputs will give you the best result, but cost £100-150.

In the absence of this, a DI box should certainly improve things. I'm a bit wary of the Behringer DI20. I bought one and exchanged it because it was so noisy and the replacement was as bad - and we're talking *really* noisy. Their DI100, however, is a little more expensive and mono-only, but an order or magnitude better.

Ok, I went down to the church to have a play with the laptop and the loop system. The multi-core although runs along the same route as the loop cable it has be cable tied to the a heating pipe so it is about 10-20cm away from it for most of it’s length only at both ends do the two cables come into direct contact with each other.

I did a test with several mics and there were no feedback problems and no interference with them with the loop amp running. The loop amp is in the same rack as the mixer and graphic ect. With the laptop problem, the hiss is reduced to a expectable level by turning the mixer volume down to nearly zero on it’s channel and putting the laptop output on near full (as suggested here, thanks guys) The sound is great quality and plenty loud enough and the hiss in the down time is minimal. This just leaves the connection squeal problem to sort this I will put a mute switch inline with the cable. Could anyone recommend switch for this? I presume a double pole double throw would the right way to go. As in a pole for each of the signals of the stereo and the double throw so the bottom throw shorts the signals the ground of the feed to the mixer to ground (would this work)?

As with regards to DIing the laptop I will do this as I don’t really want an unbalanced feed running down our multi. I presume shorting the signal in the mute switch won’t cause too much problem for the DI or the mixer. Will the DI20 do and not add noise to the signal for this situation, it is only going to be used for the PC and surely it will improve the current situation regardless?



This would suggest not but others say they are ok and would fine for this application? I don't have the funding for much better unless there is a better two channel DI for under £30 it needs to be two channel for the stereo feed.

Any advice is greatly appreciated,

Do you actually need stereo, or is it merely 'nice'?

If it's the latter, you could get one DI now and another later on if the budget people decide it's worth it.

We need stereo.

Would this be any better?

EDIT: It would have to be battery powered but with auto battery off this wouldn't require it to be turned on and off or would it?

The auto battery things usually work by sensing if an input is attached. So if you unplug the input cable end of every service you will be fine.

Do you mean unplug the cable from the DI or unplug the cable from the laptop? If it is from the laptop this will be done but from the DI it will be permanently plugged in.

Is this DI any good?

I also can't seem to find a decent switch for the mute does anyone know of any and what type I should used in regards to pole and throw?

Usually they work by when the plug is pushed in it moves a switch contact so you would have to unplug the cable from the DI, alternatively use a PSU to power it, do try powering it from the phantom power too it might work.

Would this from Maplin the DPDT version be any good for the mute switch?

EDIT: Just thought this is stupid as it would only work for a mono feed so I would need two or are then any out there suitable for stereo applications?

Short the input side, from the laptop into the DI, if I recall correctly. This way, it shouldn't cause too much of a problem for you. It shouldn't do funny things to the mixer that way, either.



I'd say a DPDT switch (double pole double throw) toggle should be just fine.
E.G:

Or an RS part: 134-1093 perhaps

EDIT: Scenmaster, that switch will be fine, if it's on the laptop (unbalanced) side rather than the balanced. Then you only need one switch. Alternatively, I'm sure RS have 4pole 2throw switches,....

Ok, just last time I ordered a DPDT the tow central pins were a signal common and the two sets of outside poles were each of the outputs in double through but there was no isolation between them as in both pins were live even though only one common was connected. I would need there to be effectively two circuits being switched for a stereo feed without them connecting I though this is what a DPDT switch does but this didn’t happen with the one I brought.

You thought correctly, may have been a mis-labelled switch.
DPDT, as I'm sure you know, is double pole. Hence two isolated poles. They also use DPDT switches for mains on/off in some circuits. Wouldn't be much good if it shorted active/neutral together!!

In addition to all the advice given, try feeding the loop from a mic, rather than from the aux out of the mixer. When I saw the name "Australian Monitor" a cold shudder went through me, and memories of burning amplifiers. That's plural. Brrrr!!

I use a laptop for my show and have no problems at all. When I first used the laptop. which is a Toshiba Satellite, I plugged into the headphones out jack and into my board. It worked, but there was some noise.

HOwever, I purchased an external sound card by sound blaster. It uses USB sound and Two RCA outs into two channels on my board. There is no noise and it works a treat.

It is about £50 for the card. Believe me, it works.

Emo Systems make a stereo passive DI box. Rugged and reliable.

I'll 2nd that. You can drive tanks over them. (Not tried that, in truth...) Available in single or dual channel.

On the USB output device theme, I have recently bought a Tascam US-122. This provides not only a stereo output (unfortunatly unbalanced), but headphones and midi too. The real plus point is that it has 'proper' microphone inputs, with phantom power, alongside midi, line and instrument inputs. So if you want a more flexible box of tricks this may be worth a look.

The loop will be through a mic soon, it always was until the install and when the loop amp got relocated. I believe it is a Shure boundary mic rigged up on the wall (this is what has always been used and apparently works well) I will relocate the wire for this and plug it into the new stage box to go to the loop amp. Would you suggest not feeding the loop from the mixer at all (reasons)?

Anyway what is wrong with Australian Monitor mixers and how did they kill your amps? I didn’t quote them for the install I was just quoted them as we needed an easy to use, rack mounted mixer for normal church use, as well as our full mixer for the youth band (which we are still raising the money for and won’t get for a while but when it comes it will probably be a soundcraft or even better an Allen and Heath )

This is quite worrying that our normal mixer has burned amps in the past, could you fill me in on details? This mixer seems ok so fair and is going to get a lot of heavy use over the next few years.

Edit: Spelling

Panzerman, Scenemaster, All,

Not wishing to tread on anyone's toes here, but unless the mic feeding a loop amp is pretty close to the sound source, the results are almost always poor. Since the mic is being spoken of in the singular, I presume you have only one to cover any source from the front of the church?

Very often, such systems sound fine when a person with normal hearing monitors it with a loop listening device, but under real conditions it could be unintelligible to a loop user.

People with hearing loss suffer a loss of hearing acuity. It is often frequency selective - with high frequencies being lost the most. This leads to the inability to hear or distinguish consonants, which carry most of the "meaning" of speech.

However, this is just the beginning of the problem, since a simple loss in level could easily be compensated by use of hearing aids.

Additional issues include problems with tinnitus, loudness and pitch, sound quality and timbre, the ability to estimate the direction and distance of a source, the recognition and analysis of speech and the ability to attend selectively to sounds of interest in the midst of competing sounds.

If the loop system picks up the target sound via a microphone located some distance away, a considerable amount of room noise and probably sound from the reverberent field is added to the signal. Those with normal hearing can use the ear/brain mechanism to filter this out. Those with hearing loss, or listening via hearing aids simply cannot handle even moderate amounts of noise and reverberation.

The majority of loop or IR systems that rely on microphones suspended over the stage or on the wall of an auditorium add so much room noise as to make them unusable.

To add insult to injury, many installers add an "ambient mic" so that users can "hear the surroundings". This was originally put in the British Standard, to help users know that the system was switched on - should there be no signal going through the loop (e.g. in a cathedral between services). However, leaving this ambient mic on all the time simply degrades the quality of signal made available to users. The original intention was that it should be switched off when the system is in use.

So, connecting the loop amp to a post fade auxiliary send on the mixer allows the microphones that are in use to drive the loop directly. Loop users get to hear the microphone that is closest to the person speaking, and they can understand what's going on.

Sorry to keep on about loop systems, but having listened to quite a few over the years, and knowing the problems that those in the Deaf Community face, I'm on a mission to improve things ;-)

Regards,

Simon Lewis

It may seem strange, but if this is a new install, are the contractors not coming back after a week or so to check it is running ok, and did you spec the PC connection when you arranged the install. I ask only because I know that when my church was spec'ing an install last year, the contractors had a big long list of things they wanted to check if we used. This was based on their previous experience (and ok it was them trying to increase the spec a bit) and in the end we said we were happy with our solution - we just wanted them to reroute the multicore under the floor and sort the rigging for projectors, speakers and plasmas in better locations.

It was Australian Monitor 100v mixer amps that gave me some serious problems, perhaps I'll post the pics of the crispy bits one day!

Simon, by all means keep on going on about induction loops, they are a seriously misunderstood thing, and whilst I can handle the "what they are, and how they work", I haven't really had any feedback from anyone who actually USES the things because they NEED to. If it helps me, and anyone else, do a better job, then I'm listening (sic). Of course it is always us chaps with good hearing that install them, set them up, then demo them to a client's foreman at handover who also has good hearing. I don't think that I have ever had later feedback, good or bad, from any of the many loops I have installed, which upon reflection, doesn't mean that the jobs have always been 100%, just that they were, and remain functional.

The problem is that certainly since October, the only reason that I am putting looooooooooads of loops in places is because construction projects are scared of falling foul of the DDA and spec them everywhere, rather than actually putting them in with a definite goal of making things intelligible for those that need it. Only a person hard-of-hearing can tell exactly what sort of a job has been done, so I hereby resolve to at least find out what the user thinks of some recent installs and see if it makes a difference to how I do future installs.
(Tiny part of your mission accomplished!)

PS
To the Original Poster, make sure you tell the install company there are problems! Don't let them go away thinking everything is hunky-dory then complain to yourself that it isn't. If they are any good, they would rather know about it immediately than 2 years down the line when work dries up because someone says "Don't use them, that install they did never worked properly". They probably aren't psychic!

Eeh, I remember when I were a lad, there'd just be a vicar and a pipe organ in a church, not a new-fangled pop band!!! (And I know which one sounds best when it is going full pelt, rattling your fillings!)

NEVER, NEVER, NEVER, NEVER, NEVER get a battery operated DI for church use. However careful you are about unplugging it to turn it of, you can *guarantee* that you or someone else will forget from time to time. And you wil only ever discover it at a critical moment, and when you've no spare batteries - despite your original committment to ensure that you always carry at least 3 spares.

I've been there!

Phantom powered or passive are the only way to go in this kind of situation. Both have their own benefits/drawbacks, but are far more fit & forget than battery operated DIs (though most phantom powered DIs have a battery option for maximum flexibility).

hi guys,
the loop system we used to use in our church was setup to run off a post fade aux.. we send the main microphone down the loop and thats it.. we have never had any complaints.. some of the people that used to use it said they only needed the main person speaking at the front, the music they could here ok.. we don't currently have a loop because the old on was run out every week around part of the hall (we meet in a school hall) and the people that used to use it either died or left.. we are looking at leasing the hall soon so are looking at installing a permanent loop system.. but I'm concerned about pickup on foldback amps/guits and such which I've experienced many times in other places..



I totaly agree.. the guy that used to look after sound years ago didn't really understand phantom power and used to insist on putting batteries in the DI boxes.. I've just took them all out and let them run phantom.. much much less hassle.. and if you have a DI box that has an Auto/On switch like ours, leave it on ON.. I've had weird problems with DI boxes left on Auto..

rgds
chris