VU BUFFER & PEAK LED KIT BUILD THREAD

Support for JLM Audio Kits

Moderator: Joe Malone

plbuzz
Posts: 3
Joined: Sat Apr 10, 2021 7:52 am

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by plbuzz »

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

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?

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Joe Malone
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by Joe Malone »

plbuzz wrote:
Sun Apr 11, 2021 4:46 am
Hi there I just purchased and received the VU Buffer and Peak LED kit and am planning my install. :D

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?
Joe :-)
JLM Audio
Capturing Audio without Injury

plbuzz
Posts: 3
Joined: Sat Apr 10, 2021 7:52 am

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by 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!

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Joe Malone
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by 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 :-)
Joe :-)
JLM Audio
Capturing Audio without Injury

audiotechyo
Posts: 2
Joined: Fri Apr 02, 2021 4:23 am

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by audiotechyo »

Joe Malone wrote:
Tue Apr 06, 2021 10:58 am
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
Posts: 3
Joined: Sat Apr 10, 2021 7:52 am

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by 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!

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Joe Malone
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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Post by Joe Malone »

plbuzz wrote:
Sat Apr 24, 2021 12:50 am
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.
Joe :-)
JLM Audio
Capturing Audio without Injury

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