VU BUFFER & PEAK LED KIT BUILD THREAD

[plbuzz]

Hi there I just purchased and received the VU Buffer and Peak LED kit and am planning my install.

I have a few questions regarding damping my VU meter as described in the Original VU Buffer Kit
build thread.

I am using a NOS Simpson VU meter and plan to limit the VU meter needle spiking on power up.

To accomplish this, what resistors/capacitors would you recommend I change out on the VU Buffer and Peak LED board as the layout differs from the Original VU Buffer board?

Thanks for your assistance.

PS - With the completed, powered, and functioning VU/Buffer kit connected to the monitored audio signal path, would there be
an effect on the monitored audio signal if power to the VU/Buffer kit is turned off and left off and then turned back on?

[Joe Malone]

Hi there I just purchased and received the VU Buffer and Peak LED kit and am planning my install.

I have a few questions regarding damping my VU meter as described in the Original VU Buffer Kit
build thread.

I am using a NOS Simpson VU meter and plan to limit the VU meter needle spiking on power up.

To accomplish this, what resistors/capacitors would you recommend I change out on the VU Buffer and Peak LED board as the layout differs from the Original VU Buffer board?

Thanks for your assistance.

PS - With the completed, powered, and functioning VU/Buffer kit connected to the monitored audio signal path, would there be
an effect on the monitored audio signal if power to the VU/Buffer kit is turned off and left off and then turned back on?

You shouldn't need to change anything on the VU buffer for the Simpson meter. It should not deflect off-scale on power up or down.

It is fine to leave the buffer connected but turned off.

Do you know if the Simpson meter has an internal diode bridge and a 3k6 resistor or not?

[plbuzz]

Thanks for getting back to me.

I tested the Simpson VU meter by adding a 3K6 in line and connecting across an iphone audio output and the VU meter worked so I am assuming the meter is complete with its own diode bridge (it is described as meeting classic VU specs in the Simpson literature).

Therefore I will be following the thread instructions for disabling the rectifier components on the buffer board.

Based on my reading of the VU board threads and the info you have provided I believe I am now good to begin the install.

I look forward to completing the build and will forward a picture of the finished product!

Thanks again!

[Joe Malone]

Yes disable the rectifier on the vu buffer and wire the meter direct to the buffer pcb without the 3k6 resistor as the buffer has a 3k3 resistor on it already.

Looking forward to see the finished photos

[audiotechyo]

Hi JD
I am away on an island with very little internet connection until the 12th April.

Your questions are very beginner electronics so would take to much time that I don’t have for me to explain to get you up to speed. Have a read of some Douglas Self books. And there are several good opamps explained book's which will explain the concept of this circuit.

Thanks for the reply, my school really only focused on digital electronics which is a real shame, and leaves me generally lost on anything beyond simple RC circuit and opamp filters. I will have a look at some of those books, thanks again!

[plbuzz]

Hello again, just finalizing the wiring schematic for my build and have an audio signal wiring related question.

I have searched the forums and still need some clarification please.

I am powering the VU buffer kit with an ungrounded and dedicated 24 VDC wall wart power supply. I am not powering any other equipment with this power supply feed.

I want to connect a female XLR receptacle to the VU Buffer audio input terminals (+In, -In, and 0v) to allow me to send balanced audio to the VU Buffer through an XLR cable from an external standard balanced preamp output.

I believe the correct balanced audio signal connection wiring between the XLR receptacle and VU Buffer is as follows:
a) XLR Pin 1 to VU Buffer Audio 0v
b) XLR Pin 2 to VU Buffer Audio +In
c) XLR Pin 3 to VU Buffer Audio -In
d) VU Buffer Audio 0v and VU Buffer Audio -In wired together on VU Buffer Board

Please confirm if the above balanced audio input wiring scheme is accurate and thanks!

[Joe Malone]

Hello again, just finalizing the wiring schematic for my build and have an audio signal wiring related question.

I have searched the forums and still need some clarification please.

I am powering the VU buffer kit with an ungrounded and dedicated 24 VDC wall wart power supply. I am not powering any other equipment with this power supply feed.

I want to connect a female XLR receptacle to the VU Buffer audio input terminals (+In, -In, and 0v) to allow me to send balanced audio to the VU Buffer through an XLR cable from an external standard balanced preamp output.

I believe the correct balanced audio signal connection wiring between the XLR receptacle and VU Buffer is as follows:
a) XLR Pin 1 to VU Buffer Audio 0v
b) XLR Pin 2 to VU Buffer Audio +In
c) XLR Pin 3 to VU Buffer Audio -In
d) VU Buffer Audio 0v and VU Buffer Audio -In wired together on VU Buffer Board

Please confirm if the above balanced audio input wiring scheme is accurate and thanks!

I believe the correct balanced audio signal connection wiring between the XLR receptacle and VU Buffer is as follows:
a) XLR Pin 1 to VU Buffer Audio 0v [Joe]Yes
b) XLR Pin 2 to VU Buffer Audio +In [Joe]Yes
c) XLR Pin 3 to VU Buffer Audio -In [Joe]Yes
d) VU Buffer Audio 0v and VU Buffer Audio -In wired together on VU Buffer Board[Joe]No this would make the input unbalanced.

Because the power supply is floating and only powering the buffer you will not have any ground loop problems.

[bigboy]

OK, got both boards soldered up and connected to ST-475's. Just wanted to confirm the setup procedure.

I am wiring these into a 30W Jean Hiraga Build, using a buck converter to get 12V from the 35V amplifier rail.

I have tested the amplifier and an input signal level of +-1.8v sine wave will generate 30W just prior to clipping at the output. I was planning on installing the VU meters at the inputs.

So, I have used a signal generator to send a 1.8v 1kHz signal to the meter and adjusted the pots so that the VU needle is at maximum position and the LED just turns on ? Is this the correct procedure ?

Cheers

Richard

[Joe Malone]

OK, got both boards soldered up and connected to ST-475's. Just wanted to confirm the setup procedure.

I am wiring these into a 30W Jean Hiraga Build, using a buck converter to get 12V from the 35V amplifier rail.

I have tested the amplifier and an input signal level of +-1.8v sine wave will generate 30W just prior to clipping at the output. I was planning on installing the VU meters at the inputs.

So, I have used a signal generator to send a 1.8v 1kHz signal to the meter and adjusted the pots so that the VU needle is at maximum position and the LED just turns on ? Is this the correct procedure ?

Cheers

Richard

HI Richard
Yes that all sounds good. Depending on type of music the VU meter will average about -6 to 10dB down compared to test tone so if you set the 1.8v to +4dB on meter it will be close. So you may need to adjust the vu meter trimpot higher. The led needs to be redone after any changing of the vu meter trimpot. So reset the led trimpot afterward to just come on as you did before as it will light instantly.

[bigboy]

Thanks Joe

Can I ask what people use the peak circuit for ? A simple LED on the from panel of the amp seems a bit simple/static. What else can be done or have yu seen done with the peak circuit ? Not that I want more holes to make on the front timber facia of the amp

[Joe Malone]

Thanks Joe

Can I ask what people use the peak circuit for ? A simple LED on the from panel of the amp seems a bit simple/static. What else can be done or have yu seen done with the peak circuit ? Not that I want more holes to make on the front timber facia of the amp

The Peak led has an extremely fast attack so lights instantly when that level is reached so good for showing an amp or pre amp is clipping or run out of headroom

[bigboy]

Thanks Joe

One last question, what does the yellow wire input connect to ? The red/black is obviously the signal input. Seems to work fine without connecting the yellow to anything ?

Richard

[Joe Malone]

Thanks Joe

One last question, what does the yellow wire input connect to ? The red/black is obviously the signal input. Seems to work fine without connecting the yellow to anything ?

Richard

If you look at the pcb in the first post on this thread Yellow 0v, black -IN and red +IN. So just depends on if you need the 0v reference or not

[bigboy]

Hi Joe

I have wired the meters at the amplifier inputs but I am having difficulty registering movement on the meters when playing real music ? No problem calibrating the meters with my signal generator and a sine wave though?

Cheers

[bigboy]

I think the issue is I am sharing the power supply from the amplifier to power the buffer but don’t fully understand the wiring needed. I use a dc-dc buck converter to reduce the +35v amplifier rail to 12v which powers the buffer. I connect the amplifier input audio rca V+ to the V+ Of the buffer board and the rca V- to the V- of the buffer board. The 0v on the buffer is not connected to anything. Is this the correct wiring ? A sketch would help greatly.

Richard