A power supply for two MV810/2 preamps. Which one?

[konsu]

Hello everyone,

I'm new to the whole DIY scene. Till now I just repaired a lot of gear, recapping or replacing faulty parts.

Now I'm faced with building/buying the right PSU for two MV 810/2 preamps.

I've already read this thread http://www.groupdiy.com/index.php?topic=34083.0 about the topic, but my Kölleda MV 810/2 is a little bit different.

I've recently purchased two MV 810/2 and am trying to get them running. After recapping one, I've managed to get a signal out of it, but it's really noisy (with a big humm). When I touch the chassis the high hissing noise goes away, but the humm is still there.

The schematics of the MV 810/2:

At the moment ground is A2a/A2b.

I'm using a psu with 24 Volt:
http://www.trcelectronics.com/Meanwell/rs-35-24.shtml

- volt is connected to pin A3b
+ volt is connected to pin A3a

Should I solder another ground connection to the chassis from pin A3a? What am I doing wrong? (probably a lot  :-[)

Thanks in advance!

 

[konsu]

Can I even use my powersupply or do I need another one?

 

[konsu]

Here is what it sounds like at the moment:

First without any input connected, then with music.

https://dl.dropbox.com/u/5370185/mv%20810%3A2%20problem%20hum.mp3

When I turn up the volume on the MV 810/2 I hear some kind of "knocking" sound. Something oscillates in the low frequency range (when I turned up the gain to the max, you hear it with quite a lot of distortion).

 

[Dr_J]

Hi,

I have racked 2 MV810 some time ago, it was a straight run!
I use a similar PSU (48V) but in addition with a JLM TREX kit.
I would say the PSU is ok.
Check your wiring, it's not a big deal!

ROCK/ON!

 

[konsu]

Hey,

I could figure it out wth some help:

You have to solder pin A3a to the ground (this kills the hum) and adjust one of the potentiometer till the pulsating switching noise from the PSU disappears.