Hi guys,

I need to set up two PA systems for an upcoming event, the first will be on a mobile stage where we will be hosting the event and the other will be approx 100M away.

Im using an stereo IEM to trasmit the sound and it works great (tested it out already) but obviously I need to delay the second PA system to take into account the speed of sound. Ive got a Behringer DEX2496 that has the programmable delay for exactly this situation but it seems like overkill to use it .

So, out of curiousity rather then need, what else is available on the market that can be used as a stereo delay (cheaply).

Thanks

Kev

Well unless you're going to be using amps in with built-in DSP (Crown XTi and the like), then I can't think of anything else on the market in current production other than what you've already suggested at the given (or lower) price-point. The dbx DriveRack PA or other "pro" equivalents are likely to be more expensive than the Behringer...

...but I too keen to hear of other suggestions if anyone has them!

Edit: Wait... 100m for IEM transmitters? If this is outdoors then to my mind it's vaguely feasible but seems rather risky to say the least! Anyone else have any experience of doing this who can confirm? I'm fried...

Yes its an outside event where both the transmitter and reciever are both line of site and are elevated so no one / thing gets in the way.

I did a 5 hour event today and it worked perfectly well for what we were doing , with only some occasional drop outs.

The 100M distance I quoted will probably end up being less so I don't think it should be a problem. If I start using it regularly then I will probabley knock up a yagi with a reasonably high gain and hook that up to the transmitter to boost the range :-)

Kev

I guess I have a different definition of what "worked perfectly" means. An antenna with gain, like a Yagi, will help get the signal out farther. You need to be careful not to exceed the legal limit for effective radiated power, but there is probably room for improvement. If you can also use a receiver that has an antenna input so you can put an antenna with gain on the receive side you won't need as radiated power from the transmitter.

The DriveRack PA will be no help to you as you need around 300ms of delay, and the DRPA only has 10ms. There are plenty of devices like XTA DPR200 series or 400 series, or similar, or even the output of a digital console that can provide large amounts of delay.

Mac

I suspect you'd want to put that yagi on the receiver, not the transmitter. Putting it on the transmitter will certainly take you beyond the licensed terms of either a ch.69 shared licence or the deregulated section of ch.70.
To draw an analogy, space shuttles transmit at very low power out of necessity; it's back here on earth at the receiving end that the clever stuff happens.

Yeah, you are right. probably better putting a yagi on the reciever. Also checked the distances and it is more like 50M , really need to get the hang of them tap measure things !!! LOL

The events are not big concerts were the sound is critical, its normally smaller public events like charity races etc where public announcements are required so the odd (and I do mean odd) dropout is not normally a problem. Obviously I would prefer no drop outs but sometimes thats life.

Kev

How about an FX processor, you might not might not be able to dial in 67.947 meters but a bit of tweaking should get somewhere close

That's what I was thinking - a delay FX unit with 0% feedback, 100% wet mix and delay adjustable my msec. Some only allow you to go in steps of 10 msec though...

If you're right about the 50 metres, you'll need about 150ms of delay. The Behringer Virtualiser effects unit goes to around 350ms and has
"course" and "fine" adjustments, the fine going down to 1ms steps. I'll doubt you'll find a stereo delay for much less than this.

I'll join the chorus of those saying that "occasional dropouts" certainly wouldn't be considered "perfect" or even "acceptable" in any professional setting. Some gain in the antenna might help with this but, to be legal in the UK, this would have to be at the receive end. Transmit EIRPs for radio mics and IEMs are regulated by law here (unlike the USA where users have no legal standing at all!) but the key phrase is EIRP. Without being too technical, "effective isotropically radiated power" roughtly means "equal power in all directions" and as soon as you use a directional antenna you'll be going over the limit since most systems already operate near the maximum allowable. A directional antenna on the receiver would certainly help though.

Bob

What sound system are you using that dosen't need delays until 100m? If you can throw that far from your main PA I would assume you were using something fairly high quality (and therfore expensive) so I wouldn't have thought you'd have a problem buying a decent delay unit? 100m is a really long way - even VDOSC or J-Series is going to see a substancial volume drop over that kind of distance...

Both Orbital and Autograph have been selling off stocks of old kit recently - why don't you try and get hold of an old BBS TCS-804? Got to be better than the Behringer...

Pair of Behringer Sharks - they will do up to 2.5second delays, and are fairly inexpensive.

Hi Gareth,

You must have had a long day I didn't say anything about a system that doesn't need delays. Its the opposite .

Im going to use the Behringer DEQ2496 that I already have, Im just asking the question about what else is available on the market to do the same cheaply.

From the answers Ive gotten so far it looks like the DEQ2496 is the way to go .

I also completely agree that oscassional drops outs are unacceptable for professional setting, but as I say, these are low budget outdoor events such as charity road runs etc. The customer doesn't normally care.

If this were a professional event and cables were out of the question, what would you use instead ???


Cheers guys

Kev

I'd still use the same setup. With a directional antenna on the receiving end. If you could use some method of attenuating the output on a transmitter and making it directional to keep your range to legal limits, this would be helpful also, I'm sure there are things that enable you to do this, but I've never used anything like it, I just use a transmitter with an OMNI antenna on a stick, or the entire thing up in the air, and a directional antenna on the receiver. I can get 150m or so before the RF level drops more than a bar DURING THE EVENT.

Drop outs shouldn't be acceptable in ANY event, be it professional or not. It's more than possible to do this job without spending a deal of money. The directional antenna is the expensive part, but you can pick one up from ebay for not alot, or a known manufacturers for not much over £100. The DEQ2496 is the perfect way to set the delay.


On another note, which serves to maybe partially answer Gareth's valid question aswell. Is this an actual DELAY. Is this designed to be a set of speakers to reinforce the sound that has failed to carry sufficiently at this given distance? Or is it just some form of "repeater" for sound from the stage to be fed to elsewhere on site, with its primary use probably being announcements etc?

If the latter, this answer the question and everything seems fine. If the former, I'd question what system was going to cover the first 100m without problem in the farthest regions before the delays. As Gareth rightly says, even the largest systems are really starting to lose their coherence and ineligibility before 100m, some of them a great deal sooner. That aside, if this IS the case, the chances are that the system controller(s) in use will have adequate delay functions on them.

CPC sell 13 element TV aerials for around £20 which you can wire using CT100 coax or the like. I have used the same setup in a 12 Acre site with one on TX and RX and transmitted nearly half a mile without dropout. The gain of the directional aerial makes up for the loss in the cable and the impedance mis match and still remains with-in the ERP limit.

This is however Northern Ireland where no-one cares and the RF spectrum is practically empty. :-)

They also add ~11.5ms just by being plugged in ;-)

Hi Andy,

Thats exactly what I did, the uper frquency of the aerial is below the IEM frequency but its close enough and I opened up the reciever (it had a wire antenna) and connected the coax directly to the PCB.

The gigs this Sunday so I will lets you know how it performs.

Kev

Blimey, you'd want to know that before sound check wouldn't you?

Try sticking a Shark in Smaart... The delay seems quite apparent, but the magnitude response doesn't settle down very nicely... perhaps the delay is dependent on what the processor is doing?

If theres one thing worse than predictable latency its unpredictable latency...

Sort of "latent latency".

Story of my life from my time in TV--in an edit suite the audio latency would change every time we added or removed a digital processing stage--it could become a nightmare in the days of digital mixers, digital effects, etc etc.

Bob

If this is something you`re going to be doing regularly I'd look out for an old Bss TCS 804? We have one and use it for doing long delay runs. They pop up on ebay sometimes??

.p.

Andy Fox from Opus Audio will tell you the TCS-804 is the best sounding delay unit ever made.

Well did the gig yesterday and it worked perfectly.

The distance between the main PA and the satellite PA was 92M.

I used a behringer DEQ2496 for the delay, a D&B IEM1100 transmitter (no modifications apart from an extension cable on the standard aerial and raised it 10ft in the air), a D&B IEM1100 receiver listed 10ft in the air (I tried two receivers - one modified with a TV aerial and one unmodified with the standard wire whip, both worked perfectly and I ended up using the standard one).

I was located close to the satellite system all day and I noticed no drop outs what so ever.

Customer was delighted, "best they have had in 25 years of the event" so next year is already booked.




Cheers folks

Kev

Well done!