Analog Allstars EQP-1S5

I threw together a pair of these Analog Allstars 500 series solid state Pultec EQP-1A clones yesterday. The build instructions were clear and they were a breeze to put together. I haven’t had a chance to give them a listen yet but I’ll report back when I do. I ended up using some Purple KDJ-4 opamps I had lying around as opposed to the original API 2520’s (yep, the solid state pultecs used API opamps) so if i don’t love them I can always try to swap them out.

The only thing I had to go back and fix was the transformer wiring. It’s clearly labeled, but I swapped the inputs and outputs. Just something to watch out for.

Hypex UCD700HxR dual mono power amplifier

While searching around for a new power amp when we upgraded to our passive ATC SCM50s I became intrigued by the idea of class D amplification. Class D has been around for a long time now, but it was only in the last couple years that a few designers were able to make it viable for professional use. One of those designers was Bruno Putzeys, the mastermind behind the UcD series from Hypex Amplification. Hypex started out as a company building OEM UcD modules while licensing Bruno’s designs from Philips, but later hired Bruno himself away to design directly for them.

Hypex will sell their amplifier modules direct to consumers, so I purchased all the parts to build a dual mono, 700w per side amp. Since I decided to go with the linear rather than switching power supplies I needed a lot of chassis to hold it all together. I ordered the largest 3ru chassis that parmetal.com makes and it still all barely fit.

How does it sound? Nothing short of astounding. I’ll be the first to admit that some of my constructions don’t live up to my high expectations, but this one crushed them out of the park. The soundscape is deeper and clearer than I ever imagined it could be. The amp even makes our NS10s shine like I’ve never heard them before.

Construction was pretty simple. Just be careful with that 120v line! I got myself pretty good on my last power amp build when I didn’t bother to put heat shrink around the IEC joint. At some point while poking around in the thing my elbow brushed against the exposed wires and  it zapped me right.

These are the power amp modules themselves

Two linear power supplies to go with those gigantic transformers

These are the modules that slowly ramp up the power so this thing doesn’t blow fuses every time you turn it on. They also prevents popping and are a bit easier on the whole system. Hypex suggests them with the UcD400, but says you’ll need them for the UcD700,and seeing how much power my UcD 400s draw with one power supply I figured I’d just take their word.

Heatsinks from diycable.com

I tried a couple different layouts but this seems to make the most sense.

I drilled out the chassis and cut the hole for the IEC jack with a dremel. Mostly I use a drill press but for some of the holes in the middle I had to go freehand.

All wired up and ready to roll

Here’s the finished amp. Yes that’s a giant chassis.

And there’s the amp in its new home under our desk

SW Custom #1: U87 Clones

I picked up a couple of poctop’s U1621 boards over at groupdiy.com. Since these are the first microphones I’ve  built I figured I’d try to stay relatively cheap by using a body from Aurycle. There’s no pattern switch, so I’m going to leave the pattering switching as jumpers inside the mic. I’m sure they’ll be in cardioid ninety five percent of the time anyway, and if not maybe I’ll just move them in to some nicer bodies further up the road. The capsule is a peluso K87i and transformer a cinemag CM-2480. They look alright on the scope but I haven’t gotten a chance to listen to them yet.

Look alright, but I still haven't listened to the damn things...