All things Green Pre

[fucanay]

Ok, I've done some checking and the phantom power is acting funny. When I turn it on I get about 36 volts under load. When I shut it off it kills the mic for a second and then comes back. When it's off it shows .9 volts and for some reason still powers my test mic (CAD GLX2200). And not just kind of powers it, but just as it did before I shut it off. There was a post in another thread that pointed at the 10uf/63V cap on the PSU board I got from Peter C as the culprit, but I want to verify this before I remove it as was suggested.

The other question I have is in regards to grounding. It seems like people are using various grounding schemes and I'm afraid I've maybe mixed some of them together. How I have it now is like this. Pin 1 on the XLR inputs go to both the 3 pin connector and to the mains star ground. The Sleeve on the outputs are going to the mains star ground. The PSU 0V is going to the mains star ground. Each board is going to the mains star ground from the 0V pin on the 4 pin PSU connector on the preamp PCB. Is this right?

I tried it out in it's current condition, and it sounds good, though I haven't done the CMRR adjustment yet because I don't know how to use a scope.

Thanks in advance.

MAtt

[/i]

 

[louder]

alo
still have trouble with the pots and switchs,but i noticed one thing in the boards.
the left leg of the out pot goes to a point where it joins with a 100nf a 10nf and a 120r resistor;and in that point there`s two holes that in some pics there`s a wire connecting those two holes.in my boards i didn`t make this connection because i thought they were connected at the solder side.
may this be the cause for my trouble?.
hope i made myself clear.
best regards
pedro

 

[Yoannv]

Hi all,

I've begin to build a quad green, and I have already finish the first one.
It works perfectly, no noise or hum, and the sound is beautiful !:grin:

But, as I am building the 3 other channels, I'm thinking about trying other caps, to learn more about their influence, and maybe increase the sound of 2 channel of my green.

I've used wima MKS2, and electro were Rubycon YXF.

First, do you think changing caps would have a great influence on Green's sound ?
I think I would try polystyrene (MKS) caps instead of Wima polyester, but for electro, I dont realy know : I can't find Nichicon HE here in Europe (I found HD, is it similar ?) so, what electrolytic caps should I try ?

Any advice is welcome...

Thanks,
Yoann

 

[matta]

Hi Yoannv,

First off, well done on your first Green! Glad you like it.

I've shared before that the caps that seem to have the most effect on the sound are the lytics and the poly bypass caps.

I have built quite a few channels with th MKS2 and Rubycon YXF and find them to have a 'sparkly' top end.

Recently in my 4 channel rack I built to the way above and then on a second pair all I did was sub the WIMA's for some Epoc Polys, and the sound is noticeably different.

The Epcos sound darker, deeper vs the WIMA's which are more open sounding and brighter, both sound great, just different.

I would advise you to build them in pairs, that way if you ever want to do stereo recording you are closely matched.

Cheers

Matt

 

[Yoannv]

Hi Matt

Thank you very much for this answer, and for you work on the meta : it has been a great help for me ! :thumb:

I think I gonna try on 2 green channels, to change just the Wima...
But, can you give me the exact reference for the Epcos ? Epcos Polys = polystyrene ?

I've make a search, it seems to be really difficult to find Epcos polystyrene in Europe... In fact, it's very hard to find any polystyrene caps...

I 'm still searching...

Thanks again,

Yoann

 

[Guest]

[quote author="Yoannv"]
I've make a search, it seems to be really difficult to find Epcos polystyrene in Europe... In fact, it's very hard to find any polystyrene caps...

I 'm still searching...

Thanks again,

Yoann[/quote]

Might be talking about polypropylene
I can only speak for Wimas but..
Look for Wima FKP02/FKP2 series
If you are after polyster (largeer values) - go for Wima MKS02/MKS2 series


The 02 is 2.5mm and the 2 is 5mm pin spacing

 

[radiance]

[quote author="Yoannv"].............

... In fact, it's very hard to find any polystyrene caps...

I 'm still searching...

Thanks again,

Yoann[/quote]

RS carries polystyrene caps..... (rs # 113-207 for example...)

 

[Flatpicker]

[quote author="Yoannv"]Hi Matt...can you give me the exact reference for the Epcos ? Epcos Polys = polystyrene ?[/quote]
He mentions MKS2 which is a metallized polyESTER, so I'm assuming that the Epcos were polyester also. The best choice here would probably be a polypropylene such as a WIMA MPK2 series or better yet a WIMA FKP2 series which they state as being "Suited for replacement of polystyrene capacitors in audio and HF applications."

 

[cannikin]

Hey Guys,

Anyone having any trouble getting the 20V diodes through the holes in the PCB, I can't seem to get them through.

****** Edit******

Dremel is a nice tool

 

[Flatpicker]

While we are sort of on the subject of caps, what type of 22pF is everyone using? I see Peter uses polystyrenes, but all I see at Mouser are ceramics.

 

[peterc]

I see Peter uses polystyrenes, but all I see at Mouser are ceramics.

I have also used 22pF NPO ceramics with no discernable change in sound. In fact, that is what I us now, I cant get the Polystyrene any longer.

Peter

 

[Flatpicker]

Thanks, Peter. I was hoping you'd say that 'cause that's all I could find, haha.

 

[Freq Band]

All Electronics....
http://www.allelectronics.com/index.html
has the 22pf polystyrenes...the same as seen in peter's board photo (I think).
But they're not in their on-line catalog. Call ?
------------------

3 QUESTIONS while I'm here....

1) Regarding the Voltage Check doc.....it says to check IC#1 with no NE5532, then with it installed.....but do I leave #1 installed when going on to IC#2, leave #2 in, and go to #3 ?....in order?.....or is there no real order, and each IC voltage check is not dependant on there being other IC's installed?

2) I have built a seperate +48v PSU.
http://members.aol.com/ecc81/ps48.html
Should there be any ground connected to that. If so, where to where ? (transformer has no ground leg on the Primary)

3) Do all grounds go to "star ground", including the IN and OUT XLR's (thereby leaving the Green board's pin 1 unconnected?) ?
(Yes, I recall this being asked before, but cannot find.)
----------------

By the way.... thank you Peterc and everyone else for the continuing support. This is a fun first "real" audio project for me. I'm not just kissing butt, I wanted to say this because I can only imagine the time involved. I'm sure I speak for many others. Pics soon !!

=FB=

 

[enthalpystudios]

hey guys.... I'm working on my green boards atm, and I can't tell if this resistor is a 10k or a 10r..... It's almost dead center on the PCB, to the left of two adjacent 47uf electrolytics, and the "+" marking of one 47uf cap is covering the resistor outline. It's value is printed really close to a 100nf cap, and I just can't read it.

If it's 10r, sweet..... if it's 10k, than I'll be damned trying to find where this 11th 10R goes.

I'm hoping that the resistor directly under the 2nd 5532 is a 10k (?)

and also, there are two 10* resistors coming right off of 3rd 5532, are those 10K?

Hopefully someone has had these bumps in the road and knows......

Thanks

billy

 

[enthalpystudios]

never mind, i'm a complete retard



miscounted my 10R's, and thought I only had 10 mounted, but I had all 11.

So i was trying to find that "missing 10R" which didn't exist.

So of course all those in question are 10K's


like I thought.


i mindfunked my self


billy

 

[HappyTom]

Here you have a nice document.
http://www.nrgrecording.de/green_pre.pdf

HT

 

[enthalpystudios]

There's a jumper right above the .01uf polycap in some of peters green pics.... what's that jumper for?


thanks

billy

 

[HappyTom]

if you are talking about the jumper behind the trimpot its not a jumper, it's preamp ground, just a place to put your signalgeneratorground and scopeground when you setup your preamps.

HT

 

[enthalpystudios]

;]

thanks!

 

[peterc]

I always found it to be a PITA when you are testing a board & one has 5 probes/croc clips hanging off a single ground point. So a loop of wire makes it much easier to attach the extra ground connections.

Peter