Great River MP-2 , info, schematics & discussions

[Bluzzi]

Greg -

I see on the schematic C20 at 220pf and R7 at 9k9. those are the only components on the Lundhal secondary so that I presume is the Zobel.

I'll just remove one pin but leave them on the PCB in case. In any case leaving it alone seems like it would just reduce HF minimally.

jim

 

[Bluzzi]

It looks like NR's layout shows J7 output connector wired backwards as well. However the connections are correct but the pin numbers should be reversed to match the schematic.

In other words orientation is correct its just pin numbering that is reversed.

So again that layout should be corrected on our copies to avoid future problems.

jim

 

[Neeno]

Hi there Samuel !
Tomorrow i'll be in Brunnen, but I don't think I have enough time to catch you... :grin:

I just need 2 of each... if it's possible...
Thank you !

[quote author="Samuel Groner"]

Does anyone have some spare 4401, 4403, mps8099 and mps8599?

Sure. Just get over the Gotthard to fetch them. :wink:

Seriously, if you still need them I'll send you a few.

Samuel[/quote]

 

[Dan Kennedy]

Neeno,

I sent you a PM a while back, but if you'll send me a snail mail address I'll throw some spare transistors in the mail for you.

 

[okgb]

Here's my quad for interest & fun , pretty jammed , not sure i could
get 4 output xfmrs in there , certainly not the whole psu
Looks like i hadn't wired up the o/l leds at that point
btw the panel was made by Dan , ddt [ or is it dtt ? ]

 

[josh]

nice job Greg. Mind if I pester you with a few questions?

Where did you get the psu, and do you have a schematic for it?

Can you help me with wiring the output Cinemags, ie which color goes where?

Please and thank you....

 

[Bluzzi]

Josh - There is a schematic for the GR PS but any PS with bipolar 30vdc and +48 will do.

the wiring for the Cinemag is for an input? Which model?

jim

 

[josh]

I have the information on which colors go where for the input transformers, but I don't have the output info. Those are what I'm wondering about and I see he has outputs on there, they are the big square ones in the back.

They are CMOQ-1
Though I am considering on saving them for my pico comp. I think they are compatible....
Options options..... What do you guys say? Use an output tranny if and when you can even if there's an input tranny? Thoughts?

 

[josh]

[quote author="Bluzzi"]Josh - There is a schematic for the GR PS but any PS with bipolar 30vdc and +48 will do

jim[/quote]

You're right, and I do have that schem. I'm just curious if that's what Greg is using. I'm writing a book on it you know :wink:

I must be progressing because I actually built the PSU for my Calrec EQ off the schematic, all point to point and everything....
too bad I still can't understand how to connect power or audio tranny's!!

 

[Bluzzi]

Josh - Your way ahead of me! I go 1 step at a time and ask every stupid question I can. Usually its because I'm just not sure and I'm too chicken to try and maybe blow something up in the process. (see below for an example)

I'm using a JLM PS kit and its very straight forward on connections.

Watch out when connecting to the MP-2 PCB as there is a wiring example that is WRONG and will blow some parts up.

I'm also using CMOQ-1 for output. See my XFR questions below.

jim

 

[Bluzzi]

If I compare the colors on the diagram below with my CMOQ-1, then mine does not have a "Brown" wire. No I'm not color blind. I do have a purplish grey wire left over after all the other colors are accounted for.

Anyone with a CMOQ-1 that can confirm the color is indeed purplish grey? Maybe Cinemag ran out of Brown?

And I guess connecting to pcb is as follows?

Brown (as per diagram but not my XFR) wire to pcb output connector pin 1 ( which is + )
Yellow wire to pcb output connector pin 2 (which is ground)

Green wire to XLR pin 2
Grey wire to XLR pin 3

Another question. Just want to confirm how to connect Lundhal LL1538XL XFR in 1:5 . Is this correct?

Lundhal pin 4 to pcb xfr primary pin 2
Lundhal pin 2 to pcb xfr primary pin 3
Chassis ground to pcb xfr primary pin 1

Lundhal pin 6 to pcb xfr secondary pin 2
Lundhal pin 5 to pcb xfr primary pin 3
Lundhal pin 8 to pcb xfr primary pin 1 (ground)

Thanks

jim

 

[okgb]

Sorry Bluzzi you are right for the lundahl , paralell
for 1:5 as in your diagram .
And looks right for the cinemag output

My pix show the jensen output , so the colors are different ,
but bluzzi posted info is correct .

The psu pcb in my photo is the Dan Great River design , which as bluzzi
mentioned feeds raw dc to the preboards which have individual regulators
so by the time it is regulated you get at least the +/- 24 and the 48
the pwr xfmr can be 22-22 for the rails , just remember that it will
increase after the diodes & smoothing caps of the psu .

Josh i think the cinemag info , or a link to their site is in this now , long
thread on how to wire the input [ i can see blk & white go the bus grnd ]
I 'll look at home later .

I think Frank corrected his site , but if you go off of the Original G.R. info
which has layout , you should be fine , never hurts to double check

regards Greg

 

[Neeno]

Hi Dan !
First of all thank you for this project, i simply love it !
Thank you for your help, but Samuel is kindly sending me some...

[quote author="Dan Kennedy"]Neeno,

I sent you a PM a while back, but if you'll send me a snail mail address I'll throw some spare transistors in the mail for you.[/quote]

 

[Bluzzi]

Greg - that is the actual Lundhal drawing on their datasheet. Thanks for confirming the wiring.

What about the Cinemag? Any comments on the Brown wire discrepancy?
All the other colors work out so I'm sure my purple-grey like one is is that one.

Maybe I should ask Cinemag.

jim

 

[okgb]

IIRC , the brown and grey do look close but it you keep on looking
[ you will be totally relaxed , every fibre of your being in deep trance ,
you will send me all your goods ........................

if you keep looking one is more gray and the other a little tan [ brown ]
looking at an output now i take the darker one to be gray

 

[Bluzzi]

Yeah - Process of ellmination.

jim

 

[3nity]

Jim the brown don't look brown at all in any Cinemag transformer.
is a kind of a light purple.

I told you that's how i wire my API's Brown (Light purple) and Red in primarys.

 

[Bluzzi]

Its OK guys I got it now. Now I know I'm not color blind.

jim

 

[evm1024]

My MP2 have been sitting built except for the gain switch. In sorting out the resistors I find that I am short one 44.2 ohm. Anyone have one sitting around they could put in the mail to me? Sourcing qty 1 locally.....

Thanks, Ethan

 

[okgb]

could find a couple different values to make that up , no ?
the originals were smt