The Seam: A Crack rebuild amongst a Snow Creek Shuffle

[ssssly]

 I bought and built a stock Crack soon after release. I added the Speedball when it came out. But other than that I never really tinkered with it. It always sounded good with my HD650s so I left well enough alone.

However, during my SR45 build my main system was down. So I was listening to headphones much more. And wouldn't you know it...the volume pot started acting up. So I thought to myself...why not replace it with an Alps. Then I thought, if I'm doing that I might as well rewire it. And I have a bunch of C-7Xs and Cree diodes because I'm experimenting with them in other power supply designs. And then I remembered that I had a box full of ridiculous Russian PIO caps. And I ended up with this.

The Seam: The result of occupying all of the available space in a Crack.

I stained the base fire engine red, sanded it back and then hand rubbed and polished 4 layers of tung oil. The inside of the case was then liberally excavated to provide enough room for the C-7X and Caps.

The top plate and TX cover are silver Rustoleum Hammer tone.

All of the hardware is brass.

The wiring is 20 AWG Lacquered Cloth Solid Core. Because its just so pretty.

The C-7X is mounted on 1/2" spacers from the original chassis ground hole to right next to the RCAs.

The cap mounts were modeled in Fusion and 3d Resin printed. They mount as a replacement for the TX isolation washers on one side and under the volume control and phono plug at the other. The clearance between the caps and the Speedball boards is tight.

Like all good Seams the caps sit a bit proud of the case bottom. So I modeled up some quick feet and resin printed them. They need some tweaking, but once I like them I'm going to cast them in AluBronze. 

The silver caps are the last power supply filter cap @ ~60uf total. The red caps are the output caps again @ ~60uf total each pair.

I mounted the Cree diode PCB to an additional 1" standoff mounted to the TX side of the Octal socket.

And they sound great. Vocals seem more forward, clearer and pronounced. The background is noticeably quieter. And I'm not sure yet if the bass is extending deeper or if the deeper bass was there but is only now apparent against the darker background. But it is definitely handling deep bass better in some way and can now be turned up louder on tracks with deep bass before clipping. But those caps need some more burn in before making a final determination. All in...I would describe the difference as a moderate polishing of what was already very good as opposed to a sea change in sonics or presentation.

It was a fun build and I learned useful things to apply to my next build. Which started today.

Thank you all again.

Time to burn in those caps a bit.

[twofires]

Whoa!

Can I ask what the 3D Print resin type is that you've used? I've often thought about using 3D printed mounts under the hood of BH designs, but worried they'd start deforming pretty quick.

[ssssly]

They are printed in plain Anycubic Black resin. In theory it's glass temp is 85C (never really tested it). But Ive used it successfully for engine intake manifolds. So I don't think the contact or ambient heat should be a problem.

And weight wise they seemed happy when I installed them. They are 5mm thick at the base and supports. Over an ~8" run of sprung I beam, back of the napkin...should hold ~50lbs+ in tension without deforming up to ~100C.

If it were PLA, ABS or even PETG, dunno. Probably a bit warm for thermoplastics other than the printable Nylon variants. Although you might be able to get away with PETG if it secured to the top plate and the bottom of the case. The heat of the top plate would soften thermoplastic enough that you'd need the cooler base support to hold stuff up once the amp was at operating temps.

But Ive had enough success using resin in tube amps that I'm designing 3D PCBs for my next big build. I have a pair of original SEX amps with the iron upgrades. Going to rebuild one stock and then build the other with 3D printed PCBs. Planning all the wiring in CAD and then I'm going to print it and selectively electroform copper to the resin wiring paths. So kind of a halfway between point to point and PCB.