peterc

Re: All things Green Pre
« Reply #900 on: April 17, 2020, 08:32:08 AM »
Yep that is the meter schem. Pot is for Output level.

The LED levels were chosen so that the lowest level is at about -40dB and the top LED illuminates at +20dB.

-40 shows 'signal present'  and +20 is the overload level of most DAW hardware these days. I really like to see an LED on whenever there is audio through the preamp, hence my not using an LM3915 which has a much smaller dynamic range.

You can change the overall levels with the trimmer, but my instructions were to set the levels for the above conditions.

Hope this helps.
Peter
If opportunity doesn't knock, build a door.


Re: All things Green Pre
« Reply #901 on: May 24, 2020, 02:48:48 PM »
Hi Guys,
Finally I finished all of the wiring of my first DIY project, tested with microphone and it's works, and now want to start to do the calibration, so my question is, can i do it without scope? and how? Sorry, I'm really newbie :)

thanks in advance

Ipin

Re: All things Green Pre
« Reply #902 on: May 31, 2020, 10:03:06 AM »
Hi Guys,
Finally I finished all of the wiring of my first DIY project, tested with microphone and it's works, and now want to start to do the calibration, so my question is, can i do it without scope? and how? Sorry, I'm really newbie :)

thanks in advance

Ipin

No worries, I didn't read the previous posts. I will have a look back at them to see if I can answer the questions. Thank you!  ;D

Ipin

Re: All things Green Pre
« Reply #903 on: June 03, 2020, 02:13:55 AM »
Hi Guys. This is my NE5532s Voltage chart of my two Green Pre.  ;D

Both Pre, Pin 1, 2, 3 of the IC No 2 (with No IC) is not in the normal range from Peter's reference.   :-\   
Does anyone know why this has happened? Is it my PSU?

(I got zero voltage on phantom power because I accidentally wire the phantom power negative to the star ground) 

Thank you Guys  :)

Ipin

peterc

Re: All things Green Pre
« Reply #904 on: June 03, 2020, 02:25:57 AM »
Hi Ipin

The important thing is the voltages with the ICs inserted are good. The other issues might be spurious voltages.

Peter
If opportunity doesn't knock, build a door.

Re: All things Green Pre
« Reply #905 on: June 03, 2020, 02:39:19 AM »
Hi Guys, also this is my IC 4 and IC 5. The first pre (green) has LED installed and the second (blue) does not have LED installed yet.
I have no idea about why some of the voltages are not in range on the chart. Does anyone know why this is?

Thank you  :)

Ipin

Re: All things Green Pre
« Reply #906 on: June 03, 2020, 02:45:50 AM »
Hi Ipin

The important thing is the voltages with the ICs inserted are good. The other issues might be spurious voltages.

Peter


Thank you Peter! btw just had a quick check of the Preamps with the condenser and dynamic microphone, and the sound amazed me! great design! Thank you Master  ;D
« Last Edit: June 03, 2020, 03:10:09 AM by ipindalieson »

peterc

Re: All things Green Pre
« Reply #907 on: June 03, 2020, 03:52:14 AM »
Thanks, enjoy them.

Peter
If opportunity doesn't knock, build a door.

Re: All things Green Pre
« Reply #908 on: June 19, 2020, 12:40:52 PM »
Hi Guys. just want to report, my 2 channels GREEN PRES is finished and I really like the sound!  ;D

Thank you Peter!!

 

peterc

Re: All things Green Pre
« Reply #909 on: June 19, 2020, 04:20:54 PM »
Looking good, love your work!
If opportunity doesn't knock, build a door.


Re: All things Green Pre
« Reply #910 on: June 21, 2020, 11:16:02 AM »
Looking good, love your work!


Thank you Peter!

I'm going to use this unit for live performances. Then I will also make another unit with an equalizer and DI input for use in the studio.  ;D
I would like to ask you some questions. Is it okay to use some 25v Caps on the board (not the 47uf 63v)? I have run out of the 35v. Will it change the sound? 

Ipin

peterc

Re: All things Green Pre
« Reply #911 on: June 21, 2020, 11:25:51 AM »
25v caps are fine for most of the circuit, but the 2 phantom blocking caps must be 63v as there is 48v across those.

Peter
If opportunity doesn't knock, build a door.

Re: All things Green Pre
« Reply #912 on: June 21, 2020, 12:26:29 PM »
25v caps are fine for most of the circuit, but the 2 phantom blocking caps must be 63v as there is 48v across those.

Peter

Thank you  :)

Re: All things Green Pre
« Reply #913 on: June 23, 2020, 10:35:27 AM »
25v caps are fine for most of the circuit, but the 2 phantom blocking caps must be 63v as there is 48v across those.

Peter

Hi Peter.

Sorry for newbie question again. I read from the first page of this thread, that people don’t seem to be using multilayer ceramic caps on this board (22pf and 150pf), are the COG caps better? I googled it also (maybe I’m wrong), it says multilayer ceramic cap are used a lot for filtering high freq, is this why? Or are they just ok to use on this board?

Thank you

Ipin

peterc

Re: All things Green Pre
« Reply #914 on: June 23, 2020, 11:25:13 AM »
C0G tend to be better but in this position, Multilayer caps are fine.

Peter
If opportunity doesn't knock, build a door.

Re: All things Green Pre
« Reply #915 on: June 24, 2020, 01:35:24 AM »
Thank you Peter  :)

Re: All things Green Pre
« Reply #916 on: August 30, 2020, 10:40:00 AM »
Hello,
I built 2  channels of the green pre (v14) with PSU 1-3-7 v6a almost 10 years ago. And I've never quite finished them, I'm getting back into DIY and I'd really like to finish that before tackling new projects.

My problem is: noise
https://soundcloud.com/amaurythewarrior/humbuzz/s-5N2bo3d1oM0

Two things, which happen with both channels, so I'm assuming PSU is the cause
Constant cyclic noise on the negative part of the spectrum, not sure I'm describing this properly



And extremely loud hum when phantom power is on. (gets louder with gain)
I'm fairly sure the ground is correctly wired. Messing with the ground wires changes it a bit, but I can't eliminate it so far. And output voltages from the PSU are good as far as I can tell.
Although phantom is a bit high I think closer to 55v.

Also, if anyone has the schematic for PSU v6a, that could allow people to help me troubleshoot, I couldn't find them.
Thanks in advance.


 

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