Great River MP-2 , info, schematics & discussions

[Dan Kennedy]

Send me an email with your snailmail address, I have them.

Just go to GreatRiverElectronics.com and send it thru the info email thingy.

I'll get it and throw some in the mail for you.

Dan

 

[madriaanse]

Email sent; wow thanks Dan!! You're a gentleman and a scholar!

M.

 

[josh]

Hey eveyone. While I'm waiting for the Cinemag group buy to ensue I'd like to ask my questions now about the things I still don't understand how to understand.

First. Looking at the schematic it seems this is the correct way to wire the resistors to the switches, or are they supposed to sawtooth into the next lead?

I have more pics showing how I made these so tidy looking if anyone is interested. I thought it worked quite well.

Second. What toroid are you all planning to use for this? How do you know this? I mean, looking at all the schematics, how can you tell which toroid will work? I'm trying to understand power supplies, I even bought the 'Audio Cyclopedia' first edition and I'm reading the power supply chapter right now, but I'm still a bit lost.

Third. This sort of fits in with #2 but I'll never know/understand if I dont ask now. What PSU are you guys using and what tells you that is what you need? Is anyone making some boards for the power section perhaps?

Please and thank you in advance everyone.

 

[Bluzzi]

Josh, no that is the way to wire it. You done good. You didn't solder the wire to the pole (the center terminal). Its a little tight trying to do it after.

You should test it with a VOM. As you turn each position should coincide with the values of the resistors at each of the 24 positions.

I haven't had time to even think about a power supply but you only need a crude one as the boards have regulation built in.


jim

 

[madriaanse]

Hi Josh,

I'm using this transformer:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=TE62075-ND

with a JLM ACDC, adjusted to +30, -30V, (and 48V):
http://www.jlmaudio.com/JLM%20Power%20Supply.htm

Hook it up according to page 7 of this assembly guide and you're set:
http://www.musiciansgig.com/ez1290/assembly.pdf

Take care,

M.

 

[Ptownkid]

Hey M

e-mail with what diodes you need and quantities.

 

[madriaanse]

Thank you Ptown! :thumb: But Dan Kennedy's already taken care of me and mailed me the parts - at no charge. Long Live Dan Kennedy!!!

M.

 

[Ptownkid]

Awesome, glad you got sorted out, what a great guy that Dan! :thumb:

 

[Neeno]

Hi Guys !
I'm hooking up one of my GR preamps...
I used Cinemag CMMI-5c for input and CMOQ-1H for the output...
I fired it up without the output trannies and it looks good on the scope.

Does anyone know how to connect the output transformer ?
Should it be connected just to J7 pin1 and pin2 ?
Primaries in series, secondaries in parallel ?

 

[okgb]

I'd say wire it 1:1

I had used the Jensen output and there was no choice , but you could check it's specs [ model listed somewhere in this thread ] and wire the Cinemag in a simular [ impedance ] way

 

[Bluzzi]

I'm getting to order my parts and its time to decide on the power supply.

I have my eye on these:

From JLM as per madianse
http://www.jlmaudio.com/JLM Power Supply.htm

From Fivefish http://www.fivefish.net/diy/

Both take the TE62075-ND from Digikey.

The JLM does 30v and the Fivefish goes to 24v max.

Thing is I will be powering 2 GR MP-2 and 2 EZ1290 in same case.

I'm thinking of getting 2 identical Power Supplies maybe to help with crosstalk and power sags.

Any suggestions as to what is my best option here? (I'm posting same in the EZ1290 build thread.)

Thanks

jim

 

[okgb]

it doesn't need to be 30 v but perhaps a couple volts above 24
separate supplies seems decadent , after all there is individual
[ local ] regulation on each preamp board , i'd say not needed .

happy d.i.y.ing regards Greg

 

[Bluzzi]

Well since I need to power 4 pres those supplies look ideal for 2 maybe 3 pres but I think they'll start to be at their peak or past it for 4.

The JLM ones look like the ticket for now as I can adjust for 24v and 30v.

I know the MP-2 has on board regulation but for the price of a JLM supply is it worth it to make a PS with just rectification? I doubt it.

jim

 

[okgb]

the psu pcb that Dan designed powered 4 pres , as long as the xfmr va
is big enough [ don't remember , check the thread & schematic] should be no problem with one raw supply , the jlm is money better spent on a project like the 9K or a.p.i. type pre .

I don't think it is like food or booze where you may double filter , to refine
but maybe , anyone ?

regards Greg

 

[Bluzzi]

Greg, don't think I'm trying to double filter but its just easier right now to get a fully rectified/regulated supply rather than build one that just rectifies. I don't think having the feed already filtered and regulated should bother the filter stage on the MP-2. Let me know if I'm mistaken here.

I'll have to research the current draw of the MP-2 and the EZ1290 and go from there. Making the transformer bigger may be necessary but the PSU still would have to be able to supply the current without frying itself.

In the meantime I'm checking out the JLM Powerstation which can feed 24v, 30v and the 48v from one unt, so that may be the one to use.

jim

 

[josh]

I went to the cinemag website before I came here to ask, but no dice.,
Input CMMI-5C and Output CMOQ-1H.

What wires are for what? I can find this information nowhere.

colors colors colors

 

[okgb]

Should be on the cinemag site , on the item page i think it is
either farther down or click on the different color word .
Worse comes to worse i'll open up mine

but basically wire the in 1:5 and the out is 1:1

the part that shows the testing circuit also has the wire colors

Brn /5 primary
red /2 primary

Org/8 secondary
Ylw / 11 secondary

brn / Org for positive polarity to keep " in phase "

white is case , blk is inner shield , hope that helps




standby

 

[Samuel Groner]

It's all in the datasheet...

Samuel

 

[josh]

D'OH!

Thanks everyone!

 

[electrog]

look close...the data sheet you linked has the colors marked on the two test circuit drawings.