Subject: Re: tweeter trees
From: James Mooney (jamesmooneycec@hotmail.co.uk)
Date: Thu Sep 07 2006 - 09:08:24 EDT
Hi Robert
Sorry for the delay in replying... Thanks very much for the advice on
tweeter trees - it's always good to get a second (or should I say first)
opinion from someone who knows what they're doing!
I have some piezo tweeters on order, and have noted your advice about
resistors (which concurs with the tech specs for the tweeter units)... I
expect progress might be slow (as is often the case in Universities) but
I'll let you know how I get on! I hope you are well, and that everything is
going well at your end!
Cheers,
James
~~~~~~
Dr James Mooney
Studio Manager
~~~~~~
Culture Lab - Newcastle
University of Newcastle upon Tyne
Grand Assembly Rooms
King's Walk
NE1 7RU
United Kingdom
~~~~~~
T: +44 (0)191 2 46 46 48
E: james.mooney@newcastle.ac.uk
~~~~~~
>From: Robert Dow <R.Dow@music.ed.ac.uk>
>Reply-To: cec-conference@concordia.ca
>To: cec-conference@concordia.ca
>Subject: Re: tweeter trees
>Date: Tue, 15 Aug 2006 18:08:47 +0100
>
>
>On 15 Aug 2006, at 12:30, James Mooney wrote:
>
>>Hello all
>>
>>I'm currently looking into building some tweeter trees to use in a live
>>sound diffusion rig, and wondered if anyone with experience in this (I
>>know you're out there!) could give me some advice...
>>
>>Firstly, I was thinking that - ideally - each tree should be able to take
>>a balanced input signal. I'm planning on hanging the trees from rigging
>>which also has mains and lighting power cables, so I think this is
>>necessary to help minimise the inevitable interference. Comments? Has
>>anyone built tweeter trees that take a balanced input signal? If not, any
>>comments on the level of unwanted noise using unbalanced inputs?
>>
>>Second, if the tweeter trees are indeed to take a balanced input signal,
>>can anyone comment on the best way of achieving this? I was hoping that
>>there might be a 'prefab' balanced-to-unbalanced conversion PCB out there
>>somewhere but so far I've been unable to track one down... Has anyone
>>heard of anything like this? I know that one can buy rackmounting
>>converters (e.g. Sonifex Redbox) but these are relatively expensive, and
>>also could not realistically be attached to the tree itself, thus more or
>>less defeating the object (you'd still have to run a fairly lengthy
>>unbalanced cable)... Other than that, the only 'converters' I've come
>>across simply short-circuit the 'cold' and ground pins, and are therefore
>>not really balanced at all!
>>
>>Finally, can anyone comment on the feasibility (or otherwise) of actually
>>making balanced-to-unbalanced conversion PCBs? I stumbled across this,
>>for example:
>>
>>http://www.jensen-transformers.com/an/an003.pdf
>>
>>The circuit diagrams don't look especially complicated to me, but then
>>again my experience of practical electronics is fairly limited...
>>
>>Any pearls of wisdom from those of you that have built tweeter trees in
>>the past would be greatly appreciated!
>
>Dear James,
>
>The BEAST tweeter trees, and the ones we have here in Scotland which are
>similar <cough>, simply take speaker level from the outputs of remote
>amplifiers on (unbalanced) speaker cable (we use 5 amp twin- flex mains
>cable). This feeds and array of tweeters. We haven't had any problems with
>interference, even when stage lighting has been around. The one thing you
>have to remember if you use the piezo- electric tweeters like the ones used
>in the BEAST trees is that their impedance goes very low at high
>frequencies, and thus you will probably have to put some sort of resistor
>between the amps and the tweeters to compensate for this. You are also
>best to EQ the signal into the tweeter amps as well, in order to attenuate
>unwanted mid/low- hi frequencies.
>
>DACs audio make both balanced->unbalanced and unbalanced->balanced modules
>on very small PCBs, and thus can fit inside existing equipment.
>
>Robert
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