All things Green Pre

[PRR]

> 20V zeners... won't fit in the PCB so maybe they were supposed to be 15V ones...

Zeners of different voltage are all the same size.

Zener size is about the power rating: 0.5 Watt, 1 Watt, etc.

 

[BladeSG]

Thanks PRR. I must have got the wrong wattage

 

[peterc]

All the project docs have been posted here :

http://www.mendelt.nl/greenpre_V14/

Thanks to Mendelt for hosting.

Peter

 

[MNA]

[quote author="clintrubber"]
FWIW: w.r.t. the gain-switch I reason a break before make would be better since it'd give you lower gain - where a make before break would give increased gain @ switching.
[/quote]
Yeah, I was wondering about this too. Wouldn't both types work equally well? With a bbm switch, the gain will drop down to +6 dB as you switch, and with a mbb switch, the gain will not drop at all, just go to the next position, right? It would be a problem if the gain was somehow adjusted the other way around, with the maximum resistance giving maximum gain, then the gain would jump up top +66 dB each time you switched (using a bbm switch, that is).

/martin.

 

[clintrubber]

from MNA:

Yeah, I was wondering about this too. Wouldn't both types work equally well? With a bbm switch, the gain will drop down to +6 dB as you switch, and with a mbb switch, the gain will not drop at all, just go to the next position, right? It would be a problem if the gain was somehow adjusted the other way around, with the maximum resistance giving maximum gain, then the gain would jump up top +66 dB each time you switched (using a bbm switch, that is).

It won't be critical - at least for this circuit not really of importance (not a general statement for all gain-switches, like you suggest already).
It's just that when the choice is there, one likes to think about which would be the better one.

I don't have the schematic here, but I thought for the bbm the gain drops to minimum during switching (the 6dB you mentioned, but I think the Green even has one step below that, so unity gain), and with a mbb, ehh, right, I thought you'd get intermediate gain-jumps but no you won't, it'd be the steady state value you'll get, directly upon moving the switch. So while still not critical, the mbb would be the most elegant.
Hadn't realized this so far, thanks for bringing this up again.
FWIW, I'll correct my order.

regards,

Peter

 

[clintrubber]

Hello,

Thanks for the zener-info, I've put 20V-types in.

Then this:

I've been looking for it but forgot whether I found something or that there wasn't anything...

Anyway: BC550C OK for the Green ? Or BC550B preferred ? The schematic says 'B'.

Regards,

Peter

 

[clintrubber]

from another thread (Jakob):

What I'm saying is that once you've bypassed the electrolytics with 100nF polyesters, there's not much difference between expensive "audio" types and run-of-the-mill standard types.

So then that big 4700uF cap of the Green gainswitch came to mind. With all other caps 100nF bypassed I feel a bit sorry for this biggo 4.7mF

So why not give it a big Wima (say 1uF) in // ? Or would I be asking for strange resonances & stuff because the ratio will be larger ?

Thanks

 

[Greg]

I'm trying to get my parts list together for a couple channels of the Green V14, and I'm having trouble with the part numbers on the BOM corresponding to the part numbers on the schematic. Which schematic was the BOM made from? It doesn't seem to be the one that is listed above.

Thanks.

 

[Ptownkid]

You could save yourself the hassle and get a package from me...


I'm not sure all the actual part numbers between the schem and the BOM correspond, shouldn't matter anyway, you need everything on that BOM anyhow.

Hope that helped

Cheers

 

[Greg]

I did consider that, but I've probably already got 60-70% of the parts already laying around. I also like to experiment with different types of caps and stuff like that. I just hate stuffing boards without a schematic. Does anyone have a schematic for the V14?

 

[Ptownkid]

Well, if you want some specific parts we can work something out...

 

[frezen]

I am also looking for an updated schematic...anybody?

 

[Ptownkid]

What parts do you still need Greg?

 

[clintrubber]

FWIW, I just realized something about the metering-section input
(please skip if it's been brought up before).

The input-leg of the metering-section uses 100nF & 10k (or 22k).
That's a highpass with f-3dB around 160 Hz (72 Hz).

Is this done deliberately ?
For now I'm assuming it's not since you'll want to display those
low freqs as well (especially those), so I'll insert a larger cap value.

Or am I missing something ?

Regards,

Peter

 

[RecPlant]

Looking to do 16 channels of the Green Pre.

What (and where) is the most up to date BOM for the GP 14 ?

Thanks,

BR

 

[jollyted]

Hi BR,

I just PM'd you with the BOM list.

We buy tons of parts for our shop each week. So I made up a complete parts 'kit' for the Green Pre 14 that I did for myself. Came out to about $43 per channel with all 1% metal film resistors, Nicicon 'lytics, Pana Ploy's, Lorlin, TI, Neutrix, Clarostat, etc., good parts. Get your PCB's from Peter. I have enough parts (packs) for 32 or 33 channels. I'm only doing 8 channels at the moment, so I have about 24 'kits' left over if you want any.

PM me back.

Regards

EDIT: Please PM me about this to keep this off the board. Thanks.

Ted

EDIT....
6/19/05 7:40 PM Pacific - all remaining parts are sold. Thanks

 

[Ptownkid]

...

 

[MEP]

jollyted,

i just PM'd you for 8.

thanks,

Bob

 

[Mendelt]

I just started sourcing parts for my green pre. Everything seems quite easy to find. Exept for the three switches. I'm trying to find pushbutton switches that fit the pcb.

Has anyone had more luck with this? Or is everyone here just using rocker switches?

Thanks

 

[clintrubber]

I just started sourcing parts for my green pre. Everything seems quite easy to find. Exept for the three switches. I'm trying to find pushbutton switches that fit the pcb.

Has anyone had more luck with this? Or is everyone here just using rocker switches?

Local supplier was able to order them. PM me with your e-mail address, I can provide details for ordering - likely your local electronicaboer can get them for you.

Or directly contact www.brigatti.nl, that's were I get them (they have to order them though, takes 1 to 2 weeks).

groeten,

Peter