Sound Skulptor MP73 – Build

Hi there!

For those who haven’t been following so far, I’ve been building some equipment for a high-quality DIY home studio for an album I’m working on for Lee Safar.

This post is about the second of two microphone preamplifier builds.  The first one ( in an earlier post ) was about the ClassicAPI VP26 ( which has a classic old 70s thick API tone), and this one, is about the Sound Skulptor MP73 ( a Neve 1290-style preamp with a warm gooey character ).

The package arrived from Sound Skulptor, so I proceeded to unwrap it:

Here is the top and bottom of the included PCB:

I started to populate the board with the diodes first, as per the excellent included instructions:

After this point however I deviate a little from the provided instructions cause I felt I had a better construction order, however, next came the resistors:

Next came the ceramic caps:

Then the film capacitors:

Then the tantalum capacitors:

Then some transistors:

Then the trimmers:

The header:

The relays:

The small electrolytic capacitors:

The terminal block connectors:

Then the main front panel switches:

Next came the potentiometers:

Then the heatsink clips were applied to the power transistor and voltage regulators:

The large electrolytic caps went in next:

The Carnhill input transformer went in next with some tricky manouvres to seat it into position:

Now the Carnhill output transformer goes in:

So then I trimmed and soldered the output transformer leads, and whacked in some IC sockets ( even though the instructions didn’t mention them, I put them in cause I have a bad track record with destroying static sensitive chips…. ):

I used the front panel, held on by the other components, to help me correctly line up the LED before soldering it, and I’m glad I did, cause now it lines up PERFECTLY.  A slight deviation from the original instructions, but easy, and accurate:

And that was it, finished!  Now I just have to do some careful cleaning of the underside of the board to remove the flux I used on the ground-plane connections ( they had to be HOT to solder properly due to the thermal dissipation…. ), but here are the shots of the final construction:

Now all that is remaining is building a power supply, casing this MP73 preamp with the VP26 one in a 1u rack case, and then, some testing.

But so far it’s looking good – not long to go now!

Catch you all soon!


5 thoughts on “Sound Skulptor MP73 – Build”

    1. Hey Kris!

      The Sound Skulptor MP73 took me around 1 and a 1/2 days to build. The power supply for it took about 4 hours to make ( I used this one: – however for a single MP73 it’s quite over-specified, but I chose it as it’s got enough power to also supply the ClassicAPI VP26 ). Casing up both the MP73 and VP26 I am estimating will take around 1-2 days.

      So total build time is around 3-4 days.

      If you are interested, the VP26 took a single day to make ( it’s a far far simpler build than the MP73 ) and the SB4000 SSL-style compressor was around a 6 day build.

      Thanks for the comment!

  1. these are exactly the pres i want to build: soundskulptor mp573 (lunchbox-version) and vp26. so if it’s possible, could you send me sounds recorded through both pres, so i could hear them? i’m really interested in the sonic differences. thx

  2. Unfortunately the MP73 pre is currently not working and I’m tracking down what I did wrong. I finally managed to power it up over the weekend and despite my careful attention to detail, something is wrong.

    Of the 3 stage amplifier it uses internally, I’ve verified that the first 2 work OK, it just seems that the final stage amp, and the biasing trimmer that sets one of the final calibrations, on my unit, is not working properly. Will post my findings when I fix it soon.

  3. Thanks to the helpful Jean-Pierre Kuhn of Sound Skulptor – I managed to fix the wiring issue that was making the MP73 wildly low-frequency oscillate when I ran through the calibration steps for it.

    After a quick adjustment to my grounding scheme, the thing is now working perfectly! Amazing stuff actually. I’m very excited about using it now. Sound samples up within the week I promise people!

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