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Old 25th March 2004, 07:41 PM   #1
owel is offline owel  United States
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Default VU Meters

Anybody have any suggestions on where to get analog VU meters?

Vintage looking the better, or 70s, 80s style era.

The only ones I can find on the net are Sifam and they're expensive at $70-$80 a piece.

Thanks
owel
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Old 25th March 2004, 10:17 PM   #2
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look for old casettedecks
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Old 25th March 2004, 10:25 PM   #3
owel is offline owel  United States
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Thanks for the reply.

Just found it this afternoon... bought an old reel to reel for $25 with 2 vu meters.

Anybody knows how to wire this thing up to measure line level signals? Do I need extra components? Does anybody have a schematic?
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Old 25th March 2004, 10:54 PM   #4
Magura is offline Magura  Denmark
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If my memory serves me well....

I once did wire an analog vu meter by a potmeter and a zener diode to ground to protect the meter against overload.

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Old 26th March 2004, 12:44 AM   #5
azira is offline azira  United States
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So your basic VU meters come in 2 varieties. Voltage driven or, more commonly, current driven. You need to read on it what the "full scale" range is. On most meters it'll say something slightly cryptic like: FS 50ua. Which stands for Full Scale: 50 micro-amps. It might say: FS 100mv if it was a voltage meter.

In any case, now that you've gotten the range right, you should go to Rod Elliots site, he's got a circuit for using analog VU meters. Project 55.
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Old 26th March 2004, 02:06 AM   #6
owel is offline owel  United States
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Thank You! This answers my question.
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Old 26th March 2004, 02:15 AM   #7
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I've used the Sifam. The AL29B is an excellent product. I didnít realize they had gotten so expensive. I know Selco US stopped carrying them.

Who is the new US rep?

A cheap and dirty way of wiring it would be to use a 10K 10-turn pot to calibrate it to zero VU when bridged across an audio line. This works assuming that the meters have built in rectifiers. One of the nice things about the Sifam is that they use very good diodes so that when they are bridged across an audio line they introduce very little distortion. ($70 bucks, they ought to)

T and H pads can also be used for isolation and calibration.

The Rod Elliot solution is nice too.
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Old 26th March 2004, 02:34 AM   #8
owel is offline owel  United States
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Do you think Germanium diodes will help, since they have a lower voltage drop?

I forgot the name of the company, but here's their email address.
Dwight (IKE) Moore [meters@ix.netcom.com]

It's $69.63 each for the AL20SQ Sifam meter.

Now, with the Sifam meters... do you just connect them across the audio lines without the need for addtl components? It will be line-level signals for a mic preamp output.
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Old 26th March 2004, 05:36 AM   #9
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I used the AL 29 bridged across +4 dB voltage matched balanced lines.

The sources ran around 50 ohms and fed high impedance inputs.

To calibrate I would use a O Vu reference tone, verifying the level with a distortion analyzer. A 10 kohm pot was used to dial in the proper meter level. Itís not a very scientific approach, but it let us deploy a lot of meters (they were only half the price a dozen or so years ago) quickly for not too much money.

Using the ESP # 55 is a better approach. Having a high impedance op amp drive the meter as this circuit does gives nice isolation form the line that is being measured. The amp has a high impendence input making its presence on the line negligible.
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Old 26th March 2004, 06:36 AM   #10
dhaen is offline dhaen  Europe
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It's probably best to buffer the audio to the VU circuit. This will prevent the distortion that might occur due to the rectifier.
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