GREEN PRE PSU?

[simonsez]

Hai guys...I'm planning to build 8 channel green preamp in a box, i found a few schematic with different version and choose to built from the original schematic. I have a few question and may be you can help me. Below is the PSU schematic,

1. I wonder if you can tell me the benefit using the transistor stage instead take directly from the output LM3xx ic regulator?
2. Is this PSU can give me enough power to fire up 8 channel pre?
3. What the benefit by passing electrolytic cap with non electrolytic cap?
4. I wan't to add line input in this box, can i use DI transformer in the input?

Thank you very much for your help....

 

[simonsez]

Nobody? ? come on guys...where are ya...

 

[peterc]

For DI purposes, I found the best way is to use an outboard DI box.

Peter

 

[Harpo]

1. I wonder if you can tell me the benefit using the transistor stage instead take directly from the output LM3xx ic regulator?

looks like a shutdown circuit if the opposite rail fails in order to limit output voltage to regulators reference voltage 1.25V.

2. Is this PSU can give me enough power to fire up 8 channel pre?

depending on mains transformer VA rating, rectifier amperage rating and size of heatsink probably yes.

3. What the benefit by passing electrolytic cap with non electrolytic cap?

difference is between schematic drawing and real world parts placement. You want this bypass cap close to the regulators input terminal if needed. Might be omitted, if distance between regulator and supply filter doesn't exceed 2" or 3". YMMV.

-Harpo

 

[simonsez]

That's what i need to know. Peter, Harpo...thank you very much. Btw, i would try with 10:1 transformer for line input. Work still in progress, Thanks guys.

 

[studiosteve]

This seems to be the most recent thread concerning the Green pre PSU, so I'll ask my question here. I'm going to use one to power a fet-boy build, I've got the Green pre PSU pcb & all the parts from a diypartsupply.com purchase. On the board I got from said retailer, there is no parts overlay, but that's OK 'cause I knew that up front.

My problem is that I can't read/make out the part overlay on the only picture I can find which is this:

http://fucanay.fischerworks.com/diy/Fetboy+24+48fromGreenPSU.gif

Does anyone know if there is a picture of this board with better resolution? I mean I'm sorry but I just can't make out what values are what. It's way too fuzzy! I have no confidence that I'm doing this correctly. If that's the best picture out there, then I guess I'll just have to deal with it. Thanks

 

[peterc]

Try here:

http://1176neve.tripod.com/id26.html

Peter

 

[studiosteve]

Peter

That's the ticket. Much better. Thank you very much.

Steve

 

[juanjovincenzo]

Hi guys!!!

I am mixer engineer but beginner in the DIY World. This is my first participation in the LAB!!

I will begin with two projects:

1) Dual Green Pre (V14 PCB's)

and

2) 8 channel Green mic pre (V14 PCB's). Because I am using an old Black ADAT link to (optical cable) a Presonus FireStudio 26x26 in/out firewire interfase and I need a group of 8 green mic preamps to put it before the ADAT.

Please, I need advices with this:

a) What PSU and powerTransformer are better for  1) Dual Green Pre (V14 PCB's) project?
and
b) What PSU and Power Transformer are better for 2) 8 channel Green mic pre (V14 PCB's) project?

OK, I found this PSU options in the Peter´s web site http://1176neve.tripod.com (thanks Peter for your great contribution):

1)Microphone Preamp Power Supply B7E  http://1176neve.tripod.com/id11.html

2)New PSU unit for Mic Pre's http://1176neve.tripod.com/id26.html


Sorry for my poor Knowledge about the power transformers, I dont know anything  :-\, and really, I dont understand How to choose the transformer and How to put together the PSU with the transformer and How many PSUs and transformes I need per each preamps or groups of preamps. Yes, I dont Know!!! but I really want to learn about this!!!! I tried to read about this in the lab forum but there are a lot INFO, so I am confused, I dont know where to start to learn about the PSU and the power transformes.

In Ecuador, we use a 110v electricity system.  


A LITLLE Contribution: I had make PDF files about the Green Pre V14 PCB, the Microphone Preamp Power Supply B7E PCB and the New PSU unit for Mic Pre's PCB. The PDFs are fit to real size and are ready to be print and transfer (good quality to print). I will try to upload in this forum these Pdfs or maybe, Peter http://1176neve.tripod.com) if you want I can send you these files and you can check these and upload in your web site. (I dont have a web site for this reason I cant support these Pdfs). I will print (lazer) the Layouts and transfer in a virgin PCB and them I will make each PCBs projects , If you guys know corrections about the Green Preamps and PSU Layouts projects , tell me please! And If you have the parts list of the Peter's PSU projects please let me know to confirm.

Excuse me for my poor english!

Thanks a lot for the patience.

Chao y suerte

Juanjo

 

[toneboner]

The files for this highly regarded project seem scattered and hard to come by, dead links, etc.  --  especially pcb transfer images.

Juan, did you ever post the .pdf you put together? 

thanks.
and yes, i realise this post is 2 years old...

 

[toneboner]

oh, you mean you have to actually READ the meta... sheesh, this place is like a sweatshop!
a .pdf would be nice tho

 

[kooma]

Old topic, but..eh:
I'm making a +\-18 and phantom psu for preamp and found one of these pcb's.
Got 18volts ok, but im thinking should i modify phantom section;
Before regulator i get nearly 80v, what is in the 38v limits of 317.
Since these are so small currents will the reg be happy or should i drop that 80v lower?
And if so, what would be best Way?
Convert voltage tripler to doubler, zeners/resistor before reg? Etc.

 

[peterc]

Kooma

There are 3 voltage doubling stages for the Phantom power. What is the voltage at the previous stage? Or on the other end on the diode? The place I am referring to is the junction of the top 2 4007s in this pic:

http://twin-x.com/groupdiy/displayimage.php?album=489&pos=1

If the voltage is high enough to drive the 317 there, then put a link into the left hand diode referred to above (second 4007 from the left).

Peter 

 

[kooma]

thanks!
I had 56V there, so changed that diode to jumper..
and just when I thought this cant be this easy, my reg isnt working
I've got 56v coming in...and same out.
changed new 317, have to double check everything, theres some stupid small error somewhere.

 

[LeeYoo]

The circuit of an LM317 is not too hard to understand.
Just a few parts.
It's ok if you have between 55v and 60v in from 15vac.
If the output is more than 48v, check:
If the regulator is the wrong way round.
Right value resistors (8k2/220ohm).
At least 10uF cap from output to ground, close to the IC, to stop the regulator from oscillating.
A negative regulator needs this even more than a positive regulator.
The LM317 can handle 40v BETWEEN in and out.
So no problem if the circuit is working ok.
It is safer to use the LM317HV (high voltage).
That one is selected for 60v.
Leo..