lanxe

Racking Channel Strips: Power Supply Question
« on: July 18, 2004, 01:39:51 PM »
i want to rack up a couple of preamps out of an old console that i have. i know that the power needs to be +-15vdc
so can i just use something like this in the rack case:
mouser part number 418-CFM1003S
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=408500&e_categoryid=103&e_pcodeid=04153

or do i need something else. i would like to stay away from wallwarts, but, if necessary i will.

another question...........
with this, or any psu, do i just run the two channel strips in parallel (knowing that the voltage will be the same across both channels in parallel)? this splits the current right? is that a problem? i am not exactly sure what current these are regulated for, or if that even matters.


thanks guys,
ryan
Ryan


owel

Racking Channel Strips: Power Supply Question
« Reply #1 on: July 18, 2004, 04:31:41 PM »
The power supply from mouser you linked to is a SWITCHING power supply. I wouldn't use them for audio, especially high gain preamps. Too noisy.  I don't think they're split power supply too.

I would just get a +/-18V AC transformer, build one of SSltech's PSU PCB and replace the regulator with 7815 and 7915 for a regulated 15V output.  

http://www.beatbazar.com/guests/ssltech/kps-1/index.htm

>with this, or any psu, do i just run the two channel strips in parallel (knowing that the voltage will be the same across both channels in parallel)? this splits the current right? is that a problem? i am not exactly sure what current these are regulated for, or if that even matters.

Yes, just connect the units in parallel.  Both units will draw current from the common power supply. I don't think preamps consume a lot of power.  So overdesign it for 1A and you'll be fine.

Hope this helps.
Owel

soundguy

Racking Channel Strips: Power Supply Question
« Reply #2 on: July 18, 2004, 04:58:51 PM »
ryan-

the supply you linked looks like its only one output, you need a dual output, + and - DC.  You want something more like this-

http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=325267&Row=30684&Site=US

If the channel strips you are mounting contain transformers, you might consider mounting the power supply outside of the rack case.  And you can just buss the power connections on the modules and hook up one end to the power supply, this is probably how the power was wired in the console...

dave

chips are good with dip...

babyhead

Racking Channel Strips: Power Supply Question
« Reply #3 on: July 18, 2004, 06:50:35 PM »
If it is a mic preamp, you will need 48v as well...

http://www.jlmaudio.com/JLM99V.htm

JLML5RPS PCB + All PCB Parts looks like a good way to go as well as ssls.

-Your buddy

b3groover

Racking Channel Strips: Power Supply Question
« Reply #4 on: July 18, 2004, 07:05:41 PM »
I just bought one of those JLM kits and put it together today.  Pretty nifty!  Two variable rails and a 48vdc rail, all in a small, regulated package.

lanxe

Racking Channel Strips: Power Supply Question
« Reply #5 on: July 19, 2004, 09:04:43 AM »
Thanks for the help, guys. Dave, i couldnt get your link to work.

those JLM kits seem to be what i am looking for. but let me ask this (i am new to this, so bare with me):
the VAC  Ov,24v connection i get, that the input from the wall.
for the VDC, it has +V1 +V2 and -V1 -V2 and 0v
the way i understand this is there are two supplies; so i could just hook up preamp 1 to +V1 -V1 and preamp 2 to +V2 -V2       is the 0v common to both preamps?

dave, instead of mounting it on the outside, can i just shield it on the inside (i assume shielding is the reason behind mounting it on the outside)?

am i looking at this right? also, the +48v is the phantom power, right?
 
anybody else have a favorite power supply they like to use in this type of situation?

thanks again for all the help
ryan
Ryan

josan

Racking Channel Strips: Power Supply Question
« Reply #6 on: July 19, 2004, 01:12:54 PM »
I racked or should I say bread boxed two channel strips (audiotronics) I used a dagnall pc mount transformer 9vac  recommended  by Kev and Peter c 's
psu board with 12 volt diodes for phantom .  You need only the one supply
for two strips  the current is sufficient  for both even with phantom.
Positive rail of the strips to  + output and  -  rail of strip to negative
you usually need a O volt or ground buss bar  with strips  as they sometimes have numerous ground points.

I mounted the psu inside the box whjich in hindsite was not so great  as I get a hum in the unit at idle but  when  mic or di box are plugged in the hum goes away so as that is the only situation the strips will be used as I'll live with it

I do like JLM 's power supply though and will probably use it for my 992's
in a 99v config  that I will get started  on soon

soundguy

Racking Channel Strips: Power Supply Question
« Reply #7 on: July 19, 2004, 01:30:06 PM »
Search for digikey part number

179-2066-ND


You can shield the inside of the box from the power transformer, but if you dont have audio transformers its probably not going to be a problem anyway.  Mumetal is really expensive, so often its just easier to build an external supply.

The power ones I reccomended above arent the best sounding supplies, FYI, but they are cheap, they are prebuilt and they are reliable, easy solution in a pinch.  You could also try to get a used acopian on ebay.  I have a brand new acopian in a box I could sell also.

dave

chips are good with dip...

owel

Racking Channel Strips: Power Supply Question
« Reply #8 on: July 19, 2004, 01:55:23 PM »
Since the +/- voltages, and +48V phantom power voltage is very common in audio projects, I just built a bunch of PCBs using SSLTech's schematic and pcb layout.

All I did was iron on the artwork, etch, drill and I'm done. You could save some money doing this.


Iron on transfer


After etching and cleaning up.


Drilled and ready for soldering.


Done.  Just add appropriate transformer.  

Thanks to SSLTech for providing the PCB artwork on his site.

lanxe

Racking Channel Strips: Power Supply Question
« Reply #9 on: July 19, 2004, 02:35:34 PM »
thats pretty sweet owel,
etching is still a little out of my range, for now........

dave,
i dont really want to cut too many corners, so i am not exactly worried about any reasonable costs. how much would you want for the acopian? do you use paypal? let me know.

JLM's power supply looks good to me.......any suggestions on the toroid transformer.

thanks again
ryan
Ryan


SSLtech

Racking Channel Strips: Power Supply Question
« Reply #10 on: July 19, 2004, 02:46:54 PM »
:thumb:

BTW, It's Kruz's site... I'm way too cheap to pay for hosting!  :wink:

Keith
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

kruz

Racking Channel Strips: Power Supply Question
« Reply #11 on: July 19, 2004, 02:54:27 PM »
Quote from: "SSLtech"
I'm way too cheap to pay for hosting!


..and i'm way to cheap to be able to design something cool like this :green:

great work Keef! :thumb:

dmlandrum

Racking Channel Strips: Power Supply Question
« Reply #12 on: July 19, 2004, 02:59:23 PM »
This would be a great PCB to offer up for sale. (hint hint) :green:  :thumb:
Darren Landrum

Be comforted that in the face of all aridity and disillusionment
And despite the changing fortunes of time,
There is always a big future in computer maintenance.

lanxe

Racking Channel Strips: Power Supply Question
« Reply #13 on: July 19, 2004, 03:03:08 PM »
what do you guys think about this mickey flickey:

http://www.welbornelabs.com/ps1.htm


where do i get a toroid transformer for the JLM

thanks
ryan
Ryan

b3groover

Racking Channel Strips: Power Supply Question
« Reply #14 on: July 19, 2004, 03:08:13 PM »
Quote from: "lanxe"
JLM's power supply looks good to me.......any suggestions on the toroid transformer.


I went with the Amveco mini-toroids from Digikey.  

http://dkc3.digikey.com/PDF/T042/1238-1239.pdf

I picked the dual 12v, 2.9A which, when run in series gives 24v at 1.5A which is plenty o' power.

http://www.amveco.com/Miniature_Low_Profile_Transformers_2.htm

JLM Audio

Racking Channel Strips: Power Supply Question
« Reply #15 on: July 21, 2004, 08:25:35 AM »
Just thought you should be aware that there is a new JLM Power Supply 3 rail PCB called the JLMAC/DC.PCB. The first batch of 120 are due back tomorrow. Double sided Soldermasked and screenprinted overlay. 3.2" x 1.7" in size and is easier to put together due to only 2 cap values and caps & diodes all face in one direction.



Joe
Joe

http://www.jlmaudio.com/shop
Capturing Audio without Injury

Mark Burnley

Racking Channel Strips: Power Supply Question
« Reply #16 on: July 21, 2004, 08:51:11 AM »
Quote from: "lanxe"
...the VAC  Ov,24v connection i get, that the input from the wall.
for the VDC, it has +V1 +V2 and -V1 -V2 and 0v
the way i understand this is there are two supplies; so i could just hook up preamp 1 to +V1 -V1 and preamp 2 to +V2 -V2       is the 0v common to both preamps?


Hi Ryan,

The AC input to the JLM board has to come from a centre-tapped transformer- there are two types you can use here- a "dual secondary" which has two entirely separate (but same voltage) windings, and a "centre tapped" secondary, which has a single winding but with a connection made to its centre.

A dual secondary would be specced like this:

Secondary Windings:

0-24
0-24


And a "centre tapped" secondary would be specced like this:

24-0-24

Either type can be used with this PSU, but make sure that you connect them up correctly- with a dual secondary the "0" of the first winding and the "24" of the second winding both need to be connected together and soldered to the "0" input pad on the board. The other side of the first winding then goes to one "24" pad, and the other side of the second winding goes to the other "24" pad on the board.

A centre tapped transformer only has three wires, the centre tap going to "0" on the board, and the two outer leads going to the "24" pads.

Joe has kindly posted the schem of the PSU- so check this PDF for the schem, and how the transformer connects to the board;

JLM 5 Rail PSU PDF

Because there are two independently-regulated split rail supplies on the board, yes you could run one module off each, but depending on the current required by the modules, you could probably run a few off each supply. The LM3x7's are good for 1.5A per device, but bear in mind that that rating is when they are well heatsinked, and the mains transformer you choose has to supply more than the maximum DC current you need.

The 48V rail is for phantom power.

Nice boards BTW Joe!

Mark
O_O tape is life O_O

JLM Audio

Racking Channel Strips: Power Supply Question
« Reply #17 on: July 21, 2004, 09:12:44 AM »
Thanks Mark.

At lot of people are running the JLM power supply from only one 22 to 24vac winding for +48v +/24v rails or one 28 to 30vac for +48v +/-34v rails for 99v. If using one 22 to 30vac winding or two 12 to 15vac windings in series connected to 0v and one of the AC terminals on the PCB which will work fine. I am fairly sure this is how Soundguy is running his. Some of the parts are actually not needed on the PCB when running this way.

I prefer a centre tapped 24(30)vac -0v -24(30)vac as this is faster cap recharge at 100 or 120Hz where as the single winding only recharges the caps at 50 or 60Hz. Read this as smoother unregulated voltage for the Regs to work with basically.

Joe
Joe

http://www.jlmaudio.com/shop
Capturing Audio without Injury

soundguy

Racking Channel Strips: Power Supply Question
« Reply #18 on: July 21, 2004, 12:48:00 PM »
Quote from: "JLM Audio"


At lot of people are running the JLM power supply from only one 24vac winding connected to 0v and one of the AC terminals which will work fine. I am fairly sure this is how Soundguy is running his. Some of the parts are actually not needed on the PCB when running this way.


aye, thats how I hooked it up, no complaints!

dave

chips are good with dip...

lanxe

Racking Channel Strips: Power Supply Question
« Reply #19 on: August 05, 2004, 08:36:12 AM »
thanks guys.
I scored an acopain, so i should be set for this project. its almost done.

Thanks for all the help,
Ryan
Ryan


 

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