Great River MP-2 , info, schematics & discussions

josh said:

Howdy all,
Is there anyone still selling pcb's for this project?
I checked ptownkid's site and pcbgrinder, but nada.

Click to expand...

Post a WTB on the BM.  PCBs and kits come up from time to time.

dmp said:

Looking at the schematic, I'd check the junction of R8 & R9 next - which is the input to the first transistor stage.

Click to expand...

I don't have any signal on R8 & R9 junction.

I have signal on J4 pin2. But not on pin 3 !
I wonder if I have a wrong jack female socket.

(I bought this preamp half done. So haven't sourced much parts myself)

Shorting J4 pin2-3. Loud and clear signal on output

So, what is the correct jack socket
Mono BNB?

socket-1-4-jack-switched-2pole

http://www.ebay.com/itm/2PCS-6-35MM-Mono-Stereo-Headphone-Microphone-Jack-1-4-Panel-ZF-Hot-Socket-/271841208086?hash=item3f4affa716:g:gYUAAOSw2XFUZcBO

http://www.ebay.com/itm/2PCS-6-35-mm-1-4-Female-Mono-Jack-Socket-Panel-PCB-Welding-free-shipping-new-/191652564422?hash=item2c9f620dc6:g:6uoAAOSwstxVVKVs

http://www.ebay.co.uk/itm/1-4inch-6-35mm-Mono-Jack-Socket-Panel-Mounting-Connector-Switched-JS22-/191441769921?hash=item2c92d195c1:m:mi6PXqBU-U2P4rceedo_Vxw
?

Ok, got some info here:
http://www.switchcraft.com/Documents/Jack_Schematics.pdf
NC - normally connected must be the thing for me.

My DI from the kit looks like this (Don't mind the wiring I never tried it out):

Although after looking at your picture I think you wired the DI jack wrongly.
It's acting like a switch. Normally the brown and white cables are connected. But if you insert a cable it cuts that connection.

The Frizzle said:

Although after looking at your picture I think you wired the DI jack wrongly.
It's acting like a switch. Normally the brown and white cables are connected. But if you insert a cable it cuts that connection.

Click to expand...

Thanks a lot Frizzle!

Edit:
Checked. None of the solder-tags are shorting to the other when jack unconnected.

G-Sun said:

Checked. None of the solder-tags are shorting to the other when jack unconnected.

Click to expand...

OK but that's not how it should be. If you move that green cable as shown:
Then Red and green are connected aren't they?

A switching  jack  breaks the connection from the secondary of the input xfmr to the preamp and then takes it from the 1/4 " cable directly when it is plugged in 

The jack has 6 pins?  basically you need a jack that breaks the connection on the signal  / tip pin
the jack should have two pins at the very end that with an ohm meter check they are connected with no jack plugged in
with a jack plugged in these two are disconnected and the tip of the plug should have contact with only one pin [ which goes onto the preamp ] the  ground is always connected to ground and never the tip and not switched , the ground is the pins closest to
opening the " middle pins " rig " if you have them are not used and the tip / signal is at the end opposite the opening
Take an unused jack & plug with a meter and check it out.

okgb said:

A switching  jack  breaks the connection from the secondary of the input xfmr to the preamp and then takes it from the 1/4 " cable directly when it is plugged in 

The jack has 6 pins?  basically you need a jack that breaks the connection on the signal  / tip pin
the jack should have two pins at the very end that with an ohm meter check they are connected with no jack plugged in
with a jack plugged in these two are disconnected and the tip of the plug should have contact with only one pin [ which goes onto the preamp ] the  ground is always connected to ground and never the tip and not switched , the ground is the pins closest to
opening the " middle pins " rig " if you have them are not used and the tip / signal is at the end opposite the opening
Take an unused jack & plug with a meter and check it out.

Click to expand...

Thank you!

I ordered these one after asking Klaus Brunner (Das Musikding):
http://www.musikding.de/63mm-Mono-jack-metal-hex-nut-solder-terminals

Yes, I'll do as you suggest, and are confident everything will be fine

btw: Seeing how many jack-configurations there are, is a little eye-opener to me.
When buying, is it generally non-switched and switched, then configurable for many types of wirings?
Or, is there 20 or so different types of jack-sockets to buy?
Edit: This image explains it pretty well (just disregard the DPDT to right)

I noticed noise was
ch1: -40dbfs
ch2: -68dbfs
into my AD on full gain.
Not a huge practical problem for me, but ch1 should be as good as ch2

I've cleaned with 2-propanol. Any easy things to check/fix beside that?

You don't need anything that deals with the ring , basically a mono 1/4" switching jack [ for the tip ]
It's a little harder to see on the switchcraft what is being switched when you plug in but that is what I used
on  a  " Marshall " style jack it's on the outside and obvious, so you need something with three pins,  that all.

Working

ch2 seems to work perfect. -63dbfs noise on max. Small resistor error on last step (volume goes down)

ch1, not working yet.  -53dbfs noise on max

This is for swapped boards from last time..
So, I'll check connection and anything but the boards.

Strange,

ch1 is passing line-level audio fine,
but nothing when I plug in my sm58.

Swapped the boards again.
Confirmed that both boards are working fine, although a little more noise on board B.

Checking connections.

Checking input transformer. Cinemag CMMI-5c.
When swapping inputXformers ch 2:
- no mic signal
- but line level signal is ok

Ch1:
- no mic signal
- line level ok

Swapping back to original transfomers

Ch1:
- no mic signal
-  no line signal

Ch2
- line signal peaking
(and giving a ok singnal on power off)
??

Checking inputXformer wiring.
Sometings seems wrong, yet it's 2 wires red and violet comming from one side , 4 wires wht, blk, yel, org comming from the other side.
White is transformer shield. Blk should be core and yel/org +/-  . And this should be secondary according to datesheet. Yet, it's wrong color for violet. That's brn in sheet.
??

I guess there are a couple of errors on ch1.
So, I'' continue with connections-checking.
Those molex-connectors can be a little flimsy it seems, or me doing it to sloppy.

Another thing that has confused me a little is the numbering on the pins.
The numbering her is oposite of number 1 on pins
http://groupdiy.com/index.php?topic=20333.msg269369#msg269369
I believe.  And that's how I've wired it.

Seem like this project is a little over my head.
I should stick with kits and good manuals

Another thing that has confused me a little is the numbering on the pins.
The numbering her is oposite of number 1 on pins

Click to expand...

It's hard to understand what you mean! 
Where does the numbering differ, between PCB and schematic or okgb's decription?
Just one connector or all of them?

Checking inputXformer wiring.
Sometings seems wrong, yet it's 2 wires red and violet comming from one side , 4 wires wht, blk, yel, org comming from the other side.
White is transformer shield. Blk should be core and yel/org +/-  . And this should be secondary according to datesheet. Yet, it's wrong color for violet. That's brn in sheet.

Click to expand...

Do you talk about  Cinemag CMMI-5c?

According to Cinemags data sheet the wire colours are:

Primary + = brown
Primary center tap -= red
Primary - = orange

Secondary + = yellow
Secondary - = green

Shields are white and black

Thanks Sranda!

Sredna said:

Another thing that has confused me a little is the numbering on the pins.
The numbering her is oposite of number 1 on pins

Click to expand...

It's hard to understand what you mean! 
Where does the numbering differ, between PCB and schematic or okgb's decription?
Just one connector or all of them?

Click to expand...

Sorry for the confusion

The molex headers have a label for pin1.
And yes, madriaanse and okgb  has numbered them the opposite way I belive.

Checking inputXformer wiring.
Sometings seems wrong, yet it's 2 wires red and violet comming from one side , 4 wires wht, blk, yel, org comming from the other side.
White is transformer shield. Blk should be core and yel/org +/-  . And this should be secondary according to datesheet. Yet, it's wrong color for violet. That's brn in sheet.

Click to expand...

Do you talk about  Cinemag CMMI-5c?

According to Cinemags data sheet the wire colours are:

Primary + = brown
Primary center tap -= red
Primary - = orange

Secondary + = yellow
Secondary - = green

Shields are white and black

Click to expand...

Yes, Cinemag CMMI-5c

Maybe mine are older, or just the color has changed on them.
See picture
red -brown
and
orange - yellow - white - black

Anyway,
I've tested the one channel that works,
and it sound great

Compared it with my ssl9k

But, as I really don't need both,
I'll sell the HP-2, as is.
Here: http://groupdiy.com/index.php?topic=60766.msg773238#msg773238

If I'm not able to sell/trade it, or I suddenly see the light,
then I'll troubleshoot some more.

But as it is, I'm a little tired,
and would like to see this unit getting in good hands.

Given there aren't any pictures or information about the MP-2 enclosure sold from Collective Cases: I thought I'd mention that the original Great River DWG PDF file that's posted here is accurate: with the exception of the four XLR holes on the Collective Cases enclosure all being sized for the Neutrik D Series connectors. That is: there are no mounts for Netrik P Series connectors (the drawing shows there are holes for two of each).