VU2 stereo VU buffer kit Build thread

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Re: VU2 stereo VU buffer kit Build thread

Postby Joe Malone » Wed Nov 02, 2016 9:47 am

thakava wrote:Hi,

Does a 12V 500mA power source work?

Best,
Tom


HI Tom
If that is 12DC 500mA regulated then yes. The VU2 only uses about 20mA of current itself. And VU meter bulbs use about 100 to 150mA each if they are not led types
Joe :-)
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XAXAU
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Re: VU2 stereo VU buffer kit Build thread

Postby XAXAU » Wed Dec 07, 2016 1:24 am

Hi Joe!

My kit didn´t come with 2x10k resistors but on the PCB it says 10k?

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Re: VU2 stereo VU buffer kit Build thread

Postby Joe Malone » Wed Dec 07, 2016 10:14 am

XAXAU wrote:Hi Joe!

My kit didn´t come with 2x10k resistors but on the PCB it says 10k?


HI Xaxau. Sorry we are not having a good run with your kits. I just check the VU2 and Kraftwerk kit batches and all other kits have 2 x 10k and 10R so somehow your 2 kits have been missed sorry.

Please let me know if you want us to send the 2 x 10k and 1 x 10R resistor out to you today?
Joe :-)

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XAXAU
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Re: VU2 stereo VU buffer kit Build thread

Postby XAXAU » Thu Dec 08, 2016 12:50 am

Joe Malone wrote:
XAXAU wrote:Hi Joe!

My kit didn´t come with 2x10k resistors but on the PCB it says 10k?


HI Xaxau. Sorry we are not having a good run with your kits. I just check the VU2 and Kraftwerk kit batches and all other kits have 2 x 10k and 10R so somehow your 2 kits have been missed sorry.

Please let me know if you want us to send the 2 x 10k and 1 x 10R resistor out to you today?

Don´t worry about it Joe. I just got the classic IKEA panic when you´re assembling furniture and there´s a screw missing! :) Are the 10K 1/4W?

I did ask you a question via mail last friday so when you find the time I´d be grateful with some help there!

Awesome kits though. I really enjoyed putting them together and now I want more! :lol:

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Re: VU2 stereo VU buffer kit Build thread

Postby Joe Malone » Thu Dec 08, 2016 10:06 am

XAXAU wrote:
Joe Malone wrote:
XAXAU wrote:Hi Joe!

My kit didn´t come with 2x10k resistors but on the PCB it says 10k?


HI Xaxau. Sorry we are not having a good run with your kits. I just check the VU2 and Kraftwerk kit batches and all other kits have 2 x 10k and 10R so somehow your 2 kits have been missed sorry.

Please let me know if you want us to send the 2 x 10k and 1 x 10R resistor out to you today?

Don´t worry about it Joe. I just got the classic IKEA panic when you´re assembling furniture and there´s a screw missing! :) Are the 10K 1/4W?

I did ask you a question via mail last friday so when you find the time I´d be grateful with some help there!

Awesome kits though. I really enjoyed putting them together and now I want more! :lol:


Yes 10k just 1/4W carbon or metal film doesn't matter for these 2 resistors. I think I just answered the email question you mention? :-)
Joe :-)

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Mikebarney
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Re: VU2 stereo VU buffer kit Build thread

Postby Mikebarney » Mon Jun 05, 2017 10:46 am

I'd like to increase the input impedance of this buffer from 47k to 100k, but I can't find a schematic that matches the circuit. Are R1 and R2 the input resistors? Any problem increasing them?
Is there a representative schematic for this circuit available?
Thanks,
Mike
PS I bought a pair of these pcbs a while ago, just getting around to building them now.

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Re: VU2 stereo VU buffer kit Build thread

Postby Joe Malone » Mon Jun 05, 2017 5:22 pm

Mikebarney wrote:I'd like to increase the input impedance of this buffer from 47k to 100k, but I can't find a schematic that matches the circuit. Are R1 and R2 the input resistors? Any problem increasing them?
Is there a representative schematic for this circuit available?
Thanks,
Mike
PS I bought a pair of these pcbs a while ago, just getting around to building them now.


HI Mike Balanced input impedance is 100k or 2 x 47k = 94k. You can change R1 & R2 for L and R to 100k each for 200k input impedance but you will have about 6dB less gain on the gain trim pot. You could just add 47k series resistors with +/-in to do get the same effect if pcb already built with 47k resistors.

Email me if you need a schematic emailed to you.
Joe :-)

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Mikebarney
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Re: VU2 stereo VU buffer kit Build thread

Postby Mikebarney » Tue Jun 06, 2017 4:19 am

Joe-
Thanks. A follow-up question:
I'm using your buffer in a power amp to drive level meters (more eye-candy than anything). I'm feeding the buffer from the unbalanced RCA inputs to the amp, which is usually a pretty low level signal having been attenuated from the source by the preamp. The meters are 1mA full scale, and after some experimentation, I found that decreasing R9 from 100 ohm to 17.4 ohm is a good compromise. Since I've increased the gain so much, I'm using your suggested pair of 1N4007 diodes in series across the meter to protect it. The meters are, however, fairly rare and expensive, so is there anything else I might do to further protect them if they are overdriven?
Thanks very much,
Mike

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Re: VU2 stereo VU buffer kit Build thread

Postby Joe Malone » Tue Jun 06, 2017 7:49 pm

Mikebarney wrote:Joe-
Thanks. A follow-up question:
I'm using your buffer in a power amp to drive level meters (more eye-candy than anything). I'm feeding the buffer from the unbalanced RCA inputs to the amp, which is usually a pretty low level signal having been attenuated from the source by the preamp. The meters are 1mA full scale, and after some experimentation, I found that decreasing R9 from 100 ohm to 17.4 ohm is a good compromise. Since I've increased the gain so much, I'm using your suggested pair of 1N4007 diodes in series across the meter to protect it. The meters are, however, fairly rare and expensive, so is there anything else I might do to further protect them if they are overdriven?
Thanks very much,
Mike


2 diodes as meter protection will usually mean the meter can never be blown. If the voltage drop across the meter is about 0.4v to 0.5v at full scale then a single diode can sometimes work as well but you do not want the diode to be starting to conduct in the meter scale at all as it will change the curve of the meter.
Joe :-)

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Re: VU2 stereo VU buffer kit Build thread

Postby Ryssen » Sat Sep 09, 2017 10:26 am

I have a class d amd (ALC1000-1300)that is bridged so I´ve been serching for a VU buffer that can work with bridge amps (ballanced).
So I googled and found yours,but my amp can leave 630W/8 ohm 63v on the outputs,I guess I´ll ned resistor (large) on the input of the VU buffer,but what value should they be?

I have a pair of vU meter I bought on ebay they are 500uA,will they work?

Åke

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Re: VU2 stereo VU buffer kit Build thread

Postby Joe Malone » Sun Sep 10, 2017 9:44 am

Ryssen wrote:I have a class d amd (ALC1000-1300)that is bridged so I´ve been serching for a VU buffer that can work with bridge amps (ballanced).
So I googled and found yours,but my amp can leave 630W/8 ohm 63v on the outputs,I guess I´ll ned resistor (large) on the input of the VU buffer,but what value should they be?

I have a pair of vU meter I bought on ebay they are 500uA,will they work?

Åke


The input to the vu buffer has 47k on each +/-in so will protect the IC from overload and high volts from the amp. First try turning the trimpot fully CCW and if the gain is still to high add 100k to 470k in series with each +/-in to drop the gain enough to be able to turn up the trimpot for your correct level. The 500uA VU meters will work fine.

If you turn the buffer gain right down and let me know how many dB to high you are still getting I can use the computer simulator of the VU buffer circuit to work out the best resistors to add in series.
Joe :-)

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Robotski
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Re: VU2 stereo VU buffer kit Build thread

Postby Robotski » Tue Sep 04, 2018 3:42 pm

Hi!
Can I feed the VU2 buffer with balanced input and take out unbalanced signal to my VU meter? That is, without the input signal getting unbalanced by this?

Thanks!

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Re: VU2 stereo VU buffer kit Build thread

Postby Joe Malone » Tue Sep 04, 2018 4:04 pm

Robotski wrote:Hi!
Can I feed the VU2 buffer with balanced input and take out unbalanced signal to my VU meter? That is, without the input signal getting unbalanced by this?

Thanks!


Yes correct the balanced input is isolated from the unbalanced output of the buffer to the VU meter.
Joe :-)

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Re: VU2 stereo VU buffer kit Build thread

Postby Robotski » Thu Sep 06, 2018 3:42 am

Ok, that's great news!
With unbalanced output, would I then just not connect the - output on the board and instead connect audio gnd to the VU meter's - ?

Thanks!

/T.

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Re: VU2 stereo VU buffer kit Build thread

Postby Joe Malone » Thu Sep 06, 2018 11:13 am

Robotski wrote:Ok, that's great news!
With unbalanced output, would I then just not connect the - output on the board and instead connect audio gnd to the VU meter's - ?

Thanks!

/T.


If isolating audio 0v and VU buffer 0v then feed unbalanced audio into +in and audio 0v to -in

If connecting all 0v together do above but join -in to 0v on VU buffer.

You can leave the -in floating but you have possibility of noise input and will have -6dB less gain.
Joe :-)

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