VU2 stereo VU buffer kit Build thread

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acidfarmer
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Re: VU2 stereo VU buffer kit Build thread

Post by acidfarmer »

Joe Malone wrote:
HI Alex
Sorry for the stuff up. Great to hear you worked it out. Strange the wrong colour code. Are the 3 pin cables in the kit short wire (150mm to 200mm) or ones with locks and 300mm wire? Photo would be great as the colour code shouldn't be changing if the right cables are being packed in the kit. Thanks for spotting the problem I will have to get this worked out ASAP as I don't want colour changes causing confusion.
Hi Joe, no problem.
It was 300 mm with lock. I'll take a picture of it this evening.
I saw it by accident, when I took another cable to test ...

Alex

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Re: VU2 stereo VU buffer kit Build thread

Post by Joe Malone »

acidfarmer wrote:
Joe Malone wrote:
HI Alex
Sorry for the stuff up. Great to hear you worked it out. Strange the wrong colour code. Are the 3 pin cables in the kit short wire (150mm to 200mm) or ones with locks and 300mm wire? Photo would be great as the colour code shouldn't be changing if the right cables are being packed in the kit. Thanks for spotting the problem I will have to get this worked out ASAP as I don't want colour changes causing confusion.
Hi Joe, no problem.
It was 300 mm with lock. I'll take a picture of it this evening.
I saw it by accident, when I took another cable to test ...

Alex
HI Alex
No need for photo we only have one with lock and the newest batch must be different 123 colour code. I will check this at the workshop tomorrow. Thanks again for bring this to my attention
Joe :-)
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maxleland
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Re: VU2 stereo VU buffer kit Build thread

Post by maxleland »

Hi there,

First of all, thank you so much for providing these incredible kits, you are a worldwide treasure!

My question is a little long, I will try to be succinct. I built the buffer kit for a pair of DuKane branded Dixson meters. I fitted them with jumpers, as the Dixson meters have internal rectifiers. In order to test the setup, I hooked the meters up to the buffer without lamps (I did sort of poke the lamp leads through on one side, just to make sure they lit up, and all seemed well), and used a 12v wall wart to provide power. I calibrated the meters, sorta, and all looked well. One issue was that one of the meter's ballistics was different than the other, slightly, and this meter also did not return to zero.

I powered down and fitted the VU2 buffer into my prototype chassis. I had a purchased an International Power power supply... WAAAYYY overkill, at 1.7 amps of output power. I setup the power supply and applied power to test, and saw 12V at the output. Then I hooked up meters and lamps and turned everything on... and the 10R resistor on the Left side, for the lamps, just lit up!!! yikes!

Any thoughts? Is that power supply to much? Thanks so much for your kits, and this great build thread, I appreciate everything you do!

~max

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Joe Malone
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Re: VU2 stereo VU buffer kit Build thread

Post by Joe Malone »

maxleland wrote:Hi there,

First of all, thank you so much for providing these incredible kits, you are a worldwide treasure!

My question is a little long, I will try to be succinct. I built the buffer kit for a pair of DuKane branded Dixson meters. I fitted them with jumpers, as the Dixson meters have internal rectifiers. In order to test the setup, I hooked the meters up to the buffer without lamps (I did sort of poke the lamp leads through on one side, just to make sure they lit up, and all seemed well), and used a 12v wall wart to provide power. I calibrated the meters, sorta, and all looked well. One issue was that one of the meter's ballistics was different than the other, slightly, and this meter also did not return to zero.

I powered down and fitted the VU2 buffer into my prototype chassis. I had a purchased an International Power power supply... WAAAYYY overkill, at 1.7 amps of output power. I setup the power supply and applied power to test, and saw 12V at the output. Then I hooked up meters and lamps and turned everything on... and the 10R resistor on the Left side, for the lamps, just lit up!!! yikes!

Any thoughts? Is that power supply to much? Thanks so much for your kits, and this great build thread, I appreciate everything you do!

~max
Hi Max need to check what current and voltage that lamp uses? The 10R is for small festoon lamps in modern meters to give it soft start for longer life. If the meter runs older normal lamps or dual lamps you may have to link out the 10R resistors. Also check some meters have 12v lamps and others 6v lamps which could do this as well. For the meters sounds like the jewel is to tight on one meter or check the magnet on the meter doesn't have any filings on it stopping it going back to -20.
Joe :-)
JLM Audio
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maxleland
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Re: VU2 stereo VU buffer kit Build thread

Post by maxleland »

Hi Joe,

Perfect! That sounds about right, I will return to this when I get off the road. The meter does indeed use dual 12V lamps, the package didn't specify current draw. Once I get home, I will jumper the connection where the 10R is supposed to go. And I will check the meters for the conditions you describe.

Thanks again!

~max

kings79
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Re: VU2 stereo VU buffer kit Build thread

Post by kings79 »

Hey All, happy to be here. I Just bought the VU2 Stereo VU Buffer PCB

Has anyone used these TN-73 VU Meter https://www.amazon.com.au/Amplifiers-He ... 060&sr=8-1 in the VU2 kit?

- Input: 1000uA±5%
- Internal Resistance: 50Ω±10%
- Size: approx. 8.2x6.2x4.5cm/3.23x2.44x1.77inch

I'm wondering if they need the diodes or not? And the 2 x RLAMP resistors = 680R for new 5v LED not 10R?

Also whats the difference between this thread and the other VU2 thread? http://www.jlmaudio.com/forum/viewtopic ... 2103#p2103

Thanks guys! :D
Last edited by kings79 on Tue Mar 16, 2021 1:59 pm, edited 1 time in total.

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Re: VU2 stereo VU buffer kit Build thread

Post by Joe Malone »

kings79 wrote:
Mon Mar 15, 2021 8:21 am
Hey All, happy to be here. I Just bought the VU2 Stereo VU Buffer PCB

Has anyone used these TN-73 VU Meter https://www.amazon.com.au/Amplifiers-He ... 060&sr=8-1 in the VU2 kit?

- Input: 1000uA±5%
- Internal Resistance: 50Ω±10%
- Size: approx. 8.2x6.2x4.5cm/3.23x2.44x1.77inch

I'm wondering if they need the diodes or not? And the 2 x RLAMP resistors = 680R for new 5v LED not 10R?

Also whats the difference between this thread and the other VU2 thread? http://www.jlmaudio.com/forum/viewtopic ... 2103#p2103

Thanks guys! :D
This thread is for the whole stereo VU meter kit we sell. The other thread is for the VU2 kit. But both can help with building the VU2.

Wow 50ohms is very low and hard to drive for a meter? I presume this is a mistake in the text. Most VU meter would be 200uA to 500uA. These meter do not have the led stickers on them so will be 12v lamps so you need at least 100mA per lamp and fit the 10R for RLAMP to the pcb for soft start so the bulbs last a long time. If you feed the meter input with a low level audio tone like 20 to 60Hz the needle should wobble on the -20 spot if no rectifier is fitted inside the meter. If the meter goes up to show a steady level higher than -20 then there is a rectifier. These meter are made with and without rectifiers and look the same from the outside.

Our version of this meter has internal rectifier & led backlighting and is actually dB accurate scale wise like sifam version.
https://www.jlmaudio.com/shop/jlm-large-vu-meter.html
Joe :-)
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kings79
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Re: VU2 stereo VU buffer kit Build thread

Post by kings79 »

Joe Malone wrote:
Mon Mar 15, 2021 9:51 am

This thread is for the whole stereo VU meter kit we sell. The other thread is for the VU2 kit. But both can help with building the VU2.

Wow 50ohms is very low and hard to drive for a meter? I presume this is a mistake in the text. Most VU meter would be 200uA to 500uA. These meter do not have the led stickers on them so will be 12v lamps so you need at least 100mA per lamp and fit the 10R for RLAMP to the pcb for soft start so the bulbs last a long time. If you feed the meter input with a low level audio tone like 20 to 60Hz the needle should wobble on the -20 spot if no rectifier is fitted inside the meter. If the meter goes up to show a steady level higher than -20 then there is a rectifier. These meter are made with and without rectifiers and look the same from the outside.

Our version of this meter has internal rectifier & led backlighting and is actually dB accurate scale wise like sifam version.
https://www.jlmaudio.com/shop/jlm-large-vu-meter.html
Thanks for the quick response Joe!

20-60Hz?? Not 1K? And at what level from a +4 Pro Tools rig?
Feed the meter straight from the soundcard OP? With no PCB/VU Buffer?

You're one has a cutout of 80mm x 37mm?

To be honest mine look EXACTLY the same as yours.

Image
Last edited by kings79 on Tue Mar 16, 2021 1:59 pm, edited 1 time in total.

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Re: VU2 stereo VU buffer kit Build thread

Post by Joe Malone »

kings79 wrote:
Mon Mar 15, 2021 10:22 am

20-60Hz?? Not 1K? And at what level from a +4 Pro Tools rig?
What I said. Low frequency. Hard to see wobble at 1khz.
Feed the meter straight from the soundcard OP? With no PCB/VU Buffer?
Direct across pin 2 and pin 3 of audio card output will work but start very low level and slowly turn it up until you can see the meter needle raises or wobbles.
You're one has a cutout of 80mm x 37mm?
Yes
To be honest mine look EXACTLY the same as yours.
They all look the same externally but completely different coil and rectifier setups make most of them not track the scale correctly especially the older ones with 12v lamps.
Joe :-)
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kings79
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Re: VU2 stereo VU buffer kit Build thread

Post by kings79 »

Putting the VU's across my Sound Card yields nothing. Even tried with cheap little VU's I have laying around.
Tried a bunch of different cables and alligator clips.

The sound card goes through a patchbay.

I do have an old pair of VU's made with your original PCB's and that works fine with the same OP's.
Last edited by kings79 on Tue Mar 16, 2021 1:59 pm, edited 1 time in total.

kings79
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Re: VU2 stereo VU buffer kit Build thread

Post by kings79 »

I measured across the VU with my Peak Atlas Pro.

I get VF=3.17V @ 5.31mv. So there must be a diode in there.

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Re: VU2 stereo VU buffer kit Build thread

Post by Joe Malone »

kings79 wrote:
Tue Mar 16, 2021 7:26 am
I measured across the VU with my Peak Atlas Pro.

I get VF=3.17V @ 5.31mv. So there must be a diode in there.

If the meter has diodes then it should work directly across any balanced pin 2 to pin 3 audio for testing.
Joe :-)
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kings79
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Re: VU2 stereo VU buffer kit Build thread

Post by kings79 »

2 different VU meters didn't as I said.

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Re: VU2 stereo VU buffer kit Build thread

Post by Joe Malone »

kings79 wrote:
Tue Mar 16, 2021 1:58 pm
2 different VU meters didn't as I said.
Just try them on the buffer output with diodes fitted on buffer to see if they work and do 1dB steps to see if the lineup to the scale or not and let me know what you find.

But the meter should work on the audio line as that is what they were designed to do but they add distortion so a buffer is the best way to isolate the distortion.
Joe :-)
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kings79
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Re: VU2 stereo VU buffer kit Build thread

Post by kings79 »

Ok, will do.

Got the PCB today.

Cheers Joe.
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