Wireless audio transmission

[Hugh Robjohns]

Yea I quite agree, the transmitter is desgined for a lapel mic, it's not meant to have what we're transmitting going through it really. The only adjusment available is the squelch on the reciever. It's only a sennheiser xs wireless kit, so not that complex.

Seems to me that you need to attenuate the output from the laptop as a first step, especially since you're very likely to run into the same problem with any replacement radio mic system!

There are lots of ways of doing it, depending on how handy you are with a soldering iron and potential divider calculations! The simplest option is a DI box, but the most cost effective would be a passive DiY attenuator.

The other thought that struck me is whether you are dealing with a stereo source from the laptop feeding a mono transmitter. All manner of opportunities for cock ups there... Unbalanced stereo into a balanced input will be very 'tinny', and some headphone outputs don't like being shorted directly together to feed an unbalanced mono input. Certainly worth checking the detail of the input wiring to the radio TX. It's also possible that the radio TX is putting out DC power for a lavalier mic, and that might upset some headphone outputs too!

...however some of the events are in the eXcel in london and I don't have a 60 meter cable or expos where I need to keep the area really clear.

60 m of cable is a lot easier and cheaper than a swanky new radio mic system, and won't suffer interference from someone else on the same channel. And if you can't run a multitouch the stage because you have to keep the area clear, how are you getting the mix output back to the speakers?

H

[Mike Stranks]

Something like the Trantec S4.4 beltpack system has a user-accessible switch to select either mic or line/instrument input.

The Alto Stealth System might suit...

The Denon DN-202 seems to be tailor-made for your application...

... and I've used systems from Digisender for similar applications in the past with no problems.

[Hugh Robjohns]

...my issue is that the presenters turn up with their notes/presentation on their mac and won't let it go, they're primarily from a slightly older generation who are technophobic in the extreme.

Speaking as someone of 'the slightly older generation', who also regularly gives presentations, I wouldn't 'let my laptop go' either. It has nothing to do with technophobia and everything to do with intellectual property! My attitude is, it's my job to bring and delver the content, and yours is to provide a range of suitable interfacing to the PA and vidoe system.

H

[Hugh Robjohns]

They've taken out the cable to the mic, and plugged in a jack to jack cable, one end in the transmitter, one end in the laptop. And yes, huge imdeance and level mis-matching.

There is no impedance mis-match. The headphone output is designed to drive earbuds and headphones which could be as low as 8 and more typically, 32 Ohms. The input of the radio TX will be at least 1k or more.

But there is, very obviously, a HUGE level mismatch. I'm actually astonished anyone would think such a simplistic approach would work at all! So there is actually noting wrong with the radio mic system, and it's not a 'narrow band' system. It's just being misused and abused.

Build a pad or go via a DI box!

H

[Hugh Robjohns]

I'm wondering if I can get away with something a bit cheap and cheerful like this Marmietk Digital Audio

What do you think?

What's he point? Cheap and cheerful is no better than what you Currently have, and you aren't using what you have appropriately at the moment anyway.

If -- and I stress the IF -- the Prosound system still sounds poor once you have sorted out the interfacing issues, then -- and only then -- would it be worth thinking about investing in a new Radio Mic system. But you will still have to deal with the input level issue with a new system too...

Ideally, I'd tell them to get a Sennheiser Digital 9000 but they're not going to stump up the cash for that.

It's no good having the gear if you have no idea what you're doing with it.... Fix the interface levels with the current equipment. Only then can you evaluate it's performance properly.

I realise I'm probably sounding a bit tetchy, but I have a low tolerance of people that blame the equipment when it's simply not being used appropriately.

H

[seablade]

Ideally, I'd tell them to get a Sennheiser Digital 9000 but they're not going to stump up the cash for that.

It's no good having the gear if you have no idea what you're doing with it.... Fix the interface levels with the current equipment. Only then can you evaluate it's performance properly.

I realise I'm probably sounding a bit tetchy, but I have a low tolerance of people that blame the equipment when it's simply not being used appropriately.

H

For the record, I completely agree with Hugh on all points, ESPECIALLY the one about finding a way to run a wire. Standard for these types of presentations around me is to build a custom podium anyways that the presenter would plug a laptop into, or a tech is dedicated to taking the presentation into a computer for the presenter and running it for them.

Now all that aside, rather than looking for a wireless mic solution, given the requirements of the average computer playback, exactly what would stop you from doing a bluetooth solution instead of a wireless RF based solution in the UHF spectrum?

There are plenty of high quality RF solutions mind you, but sometimes there is a habit of reaching for the most expensive toy, instead of getting the job done.

Seablade

[infinite granite]

Thanks all for the replies, can't believe I didn't think of the DI box, I've got one knocking around so I'll try that out first.

Interesting idea with the bluetooth, but I thought that had a limited range?

[seablade]

Thanks all for the replies, can't believe I didn't think of the DI box, I've got one knocking around so I'll try that out first.

Interesting idea with the bluetooth, but I thought that had a limited range?

Again the question remains as to what your actual requirements are. Most things will have a range of about 10m, and considering the receivers can be easily hidden on a stage and a wire run to them, I come back to looking carefully at requirements. Some bluetooth radios can have a range of about 100m theoretical which obviously would be more than enough. Hiding one of these in a podium should be quite easy and run an 1/8" jack into it. The question you have to ask yourself is, is the latency acceptable, which may require testing of the content to know for certain.

So my question about all this is... how is video and power getting to the projector and/or computer for the presentation? Why can't you run an audio wire along with one or both of them? If they are using a wireless solution for video (Certainly not common in my experience) then does it not transmit audio with it?

For the record, there are wireless solutions for line level transmission out there, for instance from Lectrosonics:
http://www.lectrosonics.com/US/Wireless-IFB/category/200-d4-s.html

Which if i needed a wireless solution, this is what I would be looking at. But I am personally still not convinced wireless is your best option.

Seablade

[Sam Spoons]

If you do finally decide to buy something else give this Wi-Digital AudioStream Pro a look. I tried one and for everything but my intended purpose (wireless IEMs) it was excellent. Price is £169 in the UK and sound quality was great, happy with a laptop or iPod headphone socket and extremely versatile (capable of two comms way use even). What let it down for me was the 18ms latency, not an issue for your application, 18ms is equivalent to being an extra 20ft from the speakers, but for in ear monitors while singing it was unacceptable to me.

They do another rig, the Wi Pro AudioMatrix that is designed for driving remote speakers (similar to the Alto Stealth system I guess) which looks as if it might be exactly what you need.

But...... I'd still use a cable if there is any way to make it possible. How do they transmit the video content to the projector? If that's wired then it must be possible to take a separate audio feed, if not is the audio embedded in the video so you could take an audio feed from the projector?