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Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Mon Apr 11, 2016 5:12 pm
by jensenmann
Thanks, Joe. I´ll try your solution first.

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Thu Apr 21, 2016 9:34 am
by giampi
hi joe
I have some vu buffer and peak LED modules.
I would put a vu meter of a tube preamp ...
unfortunately I can only have available a power 48v ... I know that they work at a max voltage of 36v ...
I can make a change in the buffer vu of the power input to make it work to 48v?
thanks for your advice
ciao :D :D

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Thu Apr 21, 2016 10:06 am
by Joe Malone
giampi wrote:hi joe
I have some vu buffer and peak LED modules.
I would put a vu meter of a tube preamp ...
unfortunately I can only have available a power 48v ... I know that they work at a max voltage of 36v ...
I can make a change in the buffer vu of the power input to make it work to 48v?
thanks for your advice
ciao :D :D
Run the 48v via something like a 1k5 to 2k2 resistor to drop the volts to 24 to 36volts going into the VU Buffer & Peak led PCB.

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Thu Jun 09, 2016 8:57 pm
by api
Hi.

I just ordered a large quantity of the these pcb´s which are going into a vintage Neve that i built a custom VU bridge for.
There will be 16 small Simpson VU´s and 5 larger ones.

My question is if i can omit the parts on the pcb that relates to the peak LED?
I will most likely not use this feature and wanted to save a few bucks on parts and also save time when building them all.

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Fri Jun 10, 2016 8:19 am
by Joe Malone
api wrote:Hi.

I just ordered a large quantity of the these pcb´s which are going into a vintage Neve that i built a custom VU bridge for.
There will be 16 small Simpson VU´s and 5 larger ones.

My question is if i can omit the parts on the pcb that relates to the peak LED?
I will most likely not use this feature and wanted to save a few bucks on parts and also save time when building them all.
Yes you can leave off D4 BAT85, C3 1uF, R9 1Meg, R10 47k, RV2 5k trimpot, RED LED.

So spare opamp half doesn't now oscillate solder opamp pin 4 & 5 together and 6 & 7 together.

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Fri Jun 10, 2016 10:06 pm
by api
Great reply Joe, and fast to, thanks!

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Thu Jun 16, 2016 12:19 am
by api
Hi again Joe.

'Two more questions for you.

If i decide to use the LED anyway, is it possible to add a larger red led?
Also, the info that the diodes by the trimmers could be something else than the BAT85, is that valid for the led diode there as well?

My meters do have internal rectification so then i could go without BAT85´s all together.

Regards,
Dennis

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Thu Jun 16, 2016 7:59 am
by Joe Malone
api wrote:Hi again Joe.

'Two more questions for you.

If i decide to use the LED anyway, is it possible to add a larger red led?
Also, the info that the diodes by the trimmers could be something else than the BAT85, is that valid for the led diode there as well?

My meters do have internal rectification so then i could go without BAT85´s all together.

Regards,
Dennis
You can use any size or colour led as long as it is high brightness type of about 600 to 1000mcd.

Since you do NOT need the meter diodes which are a critical type. The peak rectifier could just be a 1N914 / 1N4148 type.
When using the peak led make sure the kit is running on high enough power supply voltage to get to the peak level you need.
Eg if you want a peak led of +18dBu you will need a 24v power rail for the buffer kit to run on.

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Thu Aug 11, 2016 2:32 pm
by audioman8000
Hi Joe,

Why do you mention using a high speed switching diode (1N914, etc) for the peak LED circuit on your VU meter buffer board? Wouldn't a "garden variety" 1N4001 silicon diode work fine in that application?
Thanks.

Bill Wells

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Thu Aug 11, 2016 3:24 pm
by Joe Malone
audioman8000 wrote:Hi Joe,

Why do you mention using a high speed switching diode (1N914, etc) for the peak LED circuit on your VU meter buffer board? Wouldn't a "garden variety" 1N4001 silicon diode work fine in that application?
Thanks.

Bill Wells
I mention it as we normally use a low voltage drop BAT85. So I was meaning you can use a cheap 1N914 with normal voltage drop in there. You could use a 1N4001 to 7 but it will not fit on the PCB and is really not ideal.

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Fri Aug 12, 2016 3:53 pm
by audioman8000
Joe,
Thanks for your reply re the 1N4001, etc diodes for use in the peak LED circuit.
In breadboarding the VU buffer, I noticed that, if the gain adjust pot is near its highest gain position, the 1/2V voltage divider & cap (R12= R14=47K, C5=100uf) fails to ramp up all the way to 1/2 V. E.g., for a 15 VDC supply, I see more like 3 volts across C5. At that point, the buffer doesn't work properly. If I then turn down the gain adjust pot, the half-rail voltage returns to normal at about 7.5 volts. Granted, I'm using a 10K pot rather than the 5K in your schematic, since that's what I had on hand.
In any case, have you seen this situation, and how is it remedied? Thanks again.

Bill Wells

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Fri Aug 12, 2016 5:05 pm
by Joe Malone
audioman8000 wrote:Joe,
Thanks for your reply re the 1N4001, etc diodes for use in the peak LED circuit.
In breadboarding the VU buffer, I noticed that, if the gain adjust pot is near its highest gain position, the 1/2V voltage divider & cap (R12= R14=47K, C5=100uf) fails to ramp up all the way to 1/2 V. E.g., for a 15 VDC supply, I see more like 3 volts across C5. At that point, the buffer doesn't work properly. If I then turn down the gain adjust pot, the half-rail voltage returns to normal at about 7.5 volts. Granted, I'm using a 10K pot rather than the 5K in your schematic, since that's what I had on hand.
In any case, have you seen this situation, and how is it remedied? Thanks again.

Bill Wells
HI Bill if you are not using our JLM Audio printed circuit boards or kits we obviously cannot help sorry.

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Fri Oct 14, 2016 11:21 pm
by Greenjeep
I bought a vu buffer and sew 475. It's supplied with 12v and an unbalanced signal. I have the - in connected to the 0 in. When I turn it on the needle jumps. As I increase the volume of the input signal there's no needle movement or clip light activity UNTIL I'm near full volume, then suddenly everything starts working correctly. I can turn the volume back down to zero or anywhere in between and it functions perfectly. I can adjust the meter and clip light sensitivity. It's all perfect. Then if I power off, I'm back to square one. Nothing works until I crank the input signal all the way up and then back it down. Where should I start troubleshooting?

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Thu Oct 20, 2016 9:59 am
by Greenjeep
I have the meter trim pot almost all the way up. I did notice if I reduce the trim pot, the level at which the meter will suddenly start working is lower. Could this be the"latching" that is referred to in the stereo vu buffer build thread?

Re: VU BUFFER & PEAK LED KIT BUILD THREAD

Posted: Wed Oct 26, 2016 8:56 pm
by Joe Malone
Greenjeep wrote:I have the meter trim pot almost all the way up. I did notice if I reduce the trim pot, the level at which the meter will suddenly start working is lower. Could this be the"latching" that is referred to in the stereo vu buffer build thread?
To see if it is lock up which we haven't seen in this kit yet it is best to measure all 8 pins of the opamp to 0v at both gain settings and put them up on here so we can see what is going on.