Great River MP-2 , info, schematics & discussions

[okgb]

Note that with the local regulation the psu can be pretty simple BUT
also note the slightly higher than usual secondary voltage , which is part of the design

 

[Ptownkid]

So...where are we going to find this 2SK389?

 

[okgb]

Tell me how many boards you're making and i'll get them to you ,
along with the inductor
the surfacemount switch resisters are available too for whomever
takes that pcb on !

Bluzzi & udo , i'll take care of you , the majority will go to Ptown to make the kits easier & more successful [ We're trying to decide which state to Annex first , i made an offer on Arizona but they're trying to tell me it's going to ebay , yeah right ! ]

regards Greg [ who isn't smart enough to make supergreen pcbs , but i'll
help with the Great River ]

 

[Bluzzi]

Greg, can I have the transistors and inductors too? I would like to make at least 4 preamps. Let me know how much. Thanks.

I'll have a URL to the BOM very soon (it will be almost complete but maybe together we can get it to a final version.)

jim

 

[kazper]

http://www.linearsystems.com/

So...where are we going to find this 2SK389? = LSK389
:idea: hopeful.. :grin:

 

[Ptownkid]

Hey Jim, i can promise you that you'll save money by getting the whole she-bang from me.

 

[kazper]

Just incase I didn't say before... Count me in for one or two

 

[okgb]

Whoever makes boards themselves , i can get the couple parts to .

Bluzzi , i had at one time posted [ i hope ] a bom from digikey
i think it was possible to get the whole thing there , or from Ptown
our new Canadian distribution point [ for black market kits that is ]

Now how about faceplates P ?

 

[Ptownkid]

I think he's updating it though greg, which is what I've had to do slowly as well. There's a lot of obsolete parts because of Rohs, so a lot of the numbers on the BOM no longer exist.

 

[Bluzzi]

[quote author="Ptownkid"]Hey Jim, i can promise you that you'll save money by getting the whole she-bang from me.[/quote]

I don't doubt it. I'll be getting it all from you. I just want to help out those that want to do it DIY.

jim

 

[Bluzzi]

[quote author="Ptownkid"]I think he's updating it though greg, which is what I've had to do slowly as well. There's a lot of obsolete parts because of Rohs, so a lot of the numbers on the BOM no longer exist.[/quote]

Yes, I am updating it and including US prices. Also going to do the Power Supply list in case anyone wants to make that too. But I haven't found any of the passives being obsolete except for 2 parts I think.

Ptownkid, your power supply kit will have 24vdc and 48vdc for phantom as well? Enough to power 4 pres?

jim

 

[Ptownkid]

[quote author="Bluzzi"]Ptownkid, your power supply kit will have 24vdc and 48vdc for phantom as well? Enough to power 4 pres?[/quote]

Yessir, it's actually adjustable on the +/- voltages. Also, keep in mind that "enough to power four pres" really depends on the xfmr.

 

[okgb]

with a 22-0-22 secondary you should end up with a rectified +/- 30v
or so and then get regulated down to a solid 24vdc , as long as it gets
there i guess .

Go Byran Go !

 

[Ptownkid]

one question that has not been posed here is...what extras do we want in here?

2 panel mount xlrs?
What kind of switches does this pre have?
do we bother going with the million dollar elmas. or do we sub?

 

[okgb]

The elmas aren't cheap but fit the gain switch pcb if anyone goes that
route , they are gold contacts , easy to order if in the u.s. [ 27.40 each ]

Perhaps that as an option , it's also as decent a D.I. as most pres out
there , actually quite good considering nothing different is done to the
circuit

 

[hejsan]

I don't think 27 each is that much for elmas, is it? This is the knob that will be used the most..

But then, aren't Grayhills also very nice, but cheaper?

I don't really care if it mounts on the PCB or not..

my 2 kronur,
hejsan

 

[Ptownkid]

the gain switch pcb is a completely seperate pcb annnnnnnd uses smd resistors.

I don't think I'll be going for that.

I'm leaning towards soldering the resistors right to the solder tags.

 

[enthalpystudios]

i dont think grayhills are all that much cheaper than that.

its a nice pre, it would be worth it to have the good switch.... take a look at parts cost versus retail cost, and ignore your time, and it quickly becomes worth it.

besides, i have enough 12pos gain stuff around, or almost done.... 24pos is really nice, in operation.

 

[okgb]

You can get by with a 2kish reverse log pot to start until you decide
on a switch , downsides being repeatability & degradation over time

I went with the Elmas , but putting it together yourself may be less frustrating if a solder lug switch is used which could be a elma or
grayhill or whatever , think i'd go with better than the lorin though
[ but thats just me ]

 

[Bluzzi]

Lorlin only goes up to 12 positions I believe. I'll be sticking with an Elma (hey I've never bought one yet so it will be a treat).

Can we do a group buy on the Elmas? What about the input transformers?

Maybe Ptownkid should take care of all those parts too as it would be 1 shiping point. Can you do it Ptownkid? We could send you the money before you commit so that you do not get stuck with higher cost parts.

Also, is the power supply a kit or ready made?

jim