PMillett Tube Preamp Build

OK, so here's the fun I got to have today.

As I mentioned above, I ordered the Sowter 3603's a couple weeks ago. I live in the states. The order arrived today. They shipped me the style with the wires coming out the top, with the threaded grommet (option 'E'), instead of out the side (option 'F'), like I ordered. OK, it's not the end of the world. I could make that work.

But then I was looking at the wires and noticed they didn't match the published color codes for the traffo I ordered, the 3603. So I was about to email them asking them what the new color codes were, and I realized its the entirely wrong transformer. I ordered 3603f and they sent 3575e. So I bet they mixed up orders and sent me someone else's.

Good times... 

At least they sent you the transformer. I ordered a tranny from Cinemag in January and those clowns have yet to ship it out

analag said:

At least they sent you the transformer. I ordered a tranny from Cinemag in January and those clowns have yet to ship it out

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Holy  crap. I'd be bombing them with phone calls and emails!

Sowter already shipped the replacements, and I sent back the ones they sent me, yesterday.

Good luck with your cinemags!

Ricardus said:

Holy  crap. I'd be bombing them with phone calls and emails!

Sowter already shipped the replacements, and I sent back the ones they sent me, yesterday.

Good luck with your cinemags!

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Yeah I would definitely call Cinemag (not email)

I ordered a pair of transformers from Cinemag a couple months ago and turnaround was a little over a month. There must be some issue going on over there with your order

Sowter managed to finally get me the correct traffos.

My friend John printed me up some mounting cups/brackets for the new (correct) transformers.

Finally got around to doing more work. Drilled and populated the front panel. Wish I had a drill press! Even though I punched and pre-drilled with a smaller bit, two of the holes drifted a bit. I guess that's what DIY and rock and roll are all about.

I have a panel designed from Front Panel Express, but it prices out to about 150, so maybe I'll order that this fall when I have more cash on hand. The only question is, what color. I'm thinking possibly gold this time. I already have stuff from them that's blue, red, and black.

I also soldered the jumpers that will run between the PCB and the switches and pot on the front panel. This actually took a while.

The brackets my friend friend 3D printed me for the Sowters actually ended up working the way I envisioned in my head. That's a first!

Drilled and mounted the PCB standoffs. Not shown, but I ended up using some #6 washers as shims to raise them a bit and make more room for the long screws that these come with.

Got the input and output XLR jumper lines soldered, and installed the tubes. Shit just got real. Final assembly this weekend.

Because everything looks cooler with machined aluminum Neve knobs!

The build is basically done. Had a small power supply issue so I haven't really been able to test it yet. Will post pics when that happens. In the meantime, I put the schematic on the inside of the upper rack box lid, OLD SCHOOL, so long after I'm dead, if someone is still using this, the tech will have a schematic. Lots of old gear used to do this. They don't anymore.

I did some labels with my P-Touch. This isn't awesome, but it isn't awful either. Somewhere in the middle. When I get some spare cash I'll order the FPE panel I designed.

For some reason the front panel is finished with that wrinkle paint look, while the rest of the rack box is finished with more of a matte look. The labels on the XLR ins and outs in the back look better because of that.

The two channel version of this pre is officially finished, unless I buy the FPE custom panel I designed for it.

So after talking to Pete Millett in email, he was confident with an off the shelf switching PSU that has a proper ground, I could get away with putting that in the case because of all the filtering he designed into the circuit.

Outputs are balanced with Sowters.

Thing sounds very big. The one thing I noticed is the high gain mode adds some noticeable noise floor. But with a good condenser you only need to use the lower gain range anyway. I could easily peg the meters of my recorder just talking into in using my U87 clones. In that mode the thing is dead quiet and sounds amazing.

Super happy with this. Learned a lot on the way and I plan to build a 2nd one in a few months.

I think I have somewhere around $1200 into this with parts.

I was doing some listening through an old Masterlink I have kicking around. Can't wait to record with it.

A friend also made me some custom graduated markers for the pots. Laser cutters are super handy things. And in the previous pic you can see the custom transformer mounts a friend made for me with his 3D printer.

Nice build ! Congrats

TillM said:

Nice build ! Congrats

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Thank you sir!

Nice document of your journey Ricardus. Although you could have used capacitor clamps for the sorters, I really like the 3D print design and creativity used. I also like your organized process. Hopefully you will be getting some sweet recordings. Congratulations!

guavatone said:

Nice document of your journey Ricardus. Although you could have used capacitor clamps for the sorters, I really like the 3D print design and creativity used. I also like your organized process. Hopefully you will be getting some sweet recordings. Congratulations!

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Thanks!

I thought about using capacitor clamps, but I wanted to do something a little more custom than that, and my friend with the 3D printer had been bugging me to to print something, so I designed those cups/brackets.

He and I have another project we were brainstorming today, but I don't know if it's appropriate for this forum.