ASL intecom cans system

[egri]

I'm looking for some cheap lightweight headphones for use with the ASL Basic Series cans sytem. For use with BS15 beltpacks. The specification says that the mic should be 200 ohm, and that the headphones should be 50 ohm to 2 kilo-ohm. Does anyone know of a cheap alternative to buying the ASL HS1D headphones which are £50 each?

 

I was thinking of using these Gamma LH-085 headsets available from maplin for £12.99, because I already have 5 of them. (I'd need to put on 4 pin XLR plugs) However, the headphone impedence is 32 ohm, and this is less than the 50 ohm minimum on the ASL specification. Does this really matter. Can I get around this, by wiring the L and R ear in series to raise it to 64 ohm? Or perhaps soldering a resistor in the XLR plug between the pin and the wire.

 

Also I was wondering if it was possible to make an 4 pin XLR splitter cable, and wire 2 headsets off the same beltpack. Obviously, both mics would come on when you push to talk, but that's a price I'd be prepared to pay to save £116 on a beltpack. How would it be best to wire the splitter?

[egri]

Since nobody bothered to reply I'll post the answers according to Mr Brandt :-

Using the 32 ohm headphones would be a bad idea.

 

He claimed it would be possible to increase the impedence of the headphones by putting in a resistor in series, however this would half the volume as the resistor would get half the current. But it could still work.

 

Can 1 belt pack be used to drive two headphones? Yes, but the mics wouldn't work. As when 1 was being used, the other would act as a speaker. But I suppose you can always not wire the mic to one end of the splitter, or even put in some kind of switch box.

[egri]

Just to elaborate on the above, I found the following in the Clearcom manual

 

The mic and headphone wiring in the headset cord must be individually shielded. Do not connect Pins 1 (Mic common) and 3 (Headphone common) together. Headset extension cords or headset "Y" cables are not recommended because they will increase crosstalk between channels.

 

 

 

As sad as it is to be the only person to reply to my own thread, I have 2 furthur questions which I hope someone can answer, then I'll leave this forum alone.

 

Are the "Canford Techpro" and "ASL intercom" cans systems compatible?

 

A website I visited claimed they were compatible. Techpro claims to be compatible with Clearcom, and from what I can see techpro uses 24V and clearcom uses 30V. If those are compatible, then I don't see why ASL wouldn't be compatible as they too are 30V.

 

I'm also thinking of using ASL headphones with techpro beltpacks.

 

Does anyone know where I can hire ASL beltpacks from, near high wycombe

[Martin]

Are the "Canford Techpro" and "ASL intercom" cans systems compatible?

 

A website I visited claimed they were compatible. Techpro claims to be compatible with Clearcom, and from what I can see techpro uses 24V and clearcom uses 30V. If those are compatible, then I don't see why ASL wouldn't be compatible as they too are 30V.

 

I'm also thinking of using ASL headphones with techpro beltpacks.

 

<{POST_SNAPBACK}>

 

Yes, Canford Tecpro, ASL, Stonewood (Metro) Audio and Clearcom are all compatible with each other. However the "Telex RTS" system is not compatible with the above. It even uses the opposite gender connectors for headsets.

 

We have a Stonewood Audio system and also use the same ASL beltpacks with Tecpro headsets, which have much better isolation in noisy environments than the ASL headsets. Of course they are also more expensive at around £80 for the SMH210, but to be honest you are probably going to find it hard to find much suitable for less than £50.