(another) API312 build

[Moose]

Been a long time lurker, but I finally decided to post a little. Alas, all I've got to add is another API312 build that isn't even finished, but what the heck. I build guitar stuff, mic pres are a fun change and I'm excited to have something nice for myself.

For back story, I wanted to do this 5 or 6 years ago, but couldn't get my hands on 2520s. When I came back to Prodigy a while back, thinking I'd sort it all out, all the problems had been solved! Several folks have great op amps and kits and putting it all together is so easy it's almost anticlimactic.

I went with Whistlerock's ML12 board and 2520 op-amp kits. I also used his power supply and am happy I did. It's really well designed. I started with two of them, plus the EA tranny sets. They sounded so good I went ahead and ordered two more ML12 boards, op amp boards, and some DI boards. Alas, ClassicAPI was out of trannies by that point, so I have two up and running and I'll get to the other two in a couple of weeks.

Mike at Whistlerock let me have the ML12 boards before they were officially released, and was super helpful. I'm glad, because they have some great features -- they fit 4 in a 1u rack with ease, have an automatically switching DI option, and include a header for the extra winding on the tranny in case you want to set up metering or do a monitor out. I was a little reticent about the pot instead of a stepped attenuator, but then I thought "They're APIs! The trannies are iron, and I'll probably cook the 550s in the op amp until they're out of range, anyway!" I was foolish to have worried -- the pot is actually nice, and allows fine tuning of gain with ease.

The only difficult part of this project might be the op amps, which require actual skill with a soldering iron. I've built a hundred guitar pedals and a score of amps, and done enough repairs that I can ham fist my way through almost any PCB, but for a beginner the op amp kit will require patience.

Results are fantastic. Certifiable buttloads of headroom, distinctively rich but pleasingly open sound, and I'm dying to get someone into the studio who can really sing and play so I can engineer with these things.

Some pics of the build (In process, only two channels are done):

A stuffed board:

Test fitting the case:

Two channels working + the Whistlerock PSU

I made some samples using this rig:

The samples were done as simply as possible. Used the API and an FMR RNP (the most honest and bland preamp I have) into a pair of pretty well matched SDCs. I set the mics up as close as possible to each other, then stood in front of them with an instrument and made some noise.


http://toneslut.com/sounds/samples/API/ShakeShakeShake_API.mp3
http://toneslut.com/sounds/samples/API/ShakeShakeShake_RNP.mp3

http://toneslut.com/sounds/samples/API/IggyLeLe_API.mp3
http://toneslut.com/sounds/samples/API/IggyLeLe_RNP.mp3

http://toneslut.com/sounds/samples/API/HighString_API.mp3
http://toneslut.com/sounds/samples/API/HighString_RNP.mp3

http://toneslut.com/sounds/samples/API/DtunedAcoustic_API.mp3
http://toneslut.com/sounds/samples/API/DtunedAcoustic_RNP.mp3

APIs rock. I feel like, with two of these and some talent, I could record Siamese Dream. In fact, the only thing that I can't rave about on this project is the case, which I bought from Circuit Specialists. I'd have done better with a basic case from Par Metal for the extra $20.


In summary:

• Classic API are great to deal with
• Whistlerock's boards, op amps, and power supplies are highly recommended
• The EA trannies are perfect for this type of amp
• The project was entirely too easy

 

[mikefatom]

Hey Moose,

This is beautifully done!  Good job!
You wired up the power headers exactly the way I intended it to be. 

Post some more pictures when you finalize the build.

Cheers,

Mike

 

[Moose]

Will do. It's happily in the rack at the moment and doing work, but I'll have to show those DIs hanging off the output jacks. Pretty slick way of doing it.  I'll post them when I get the trannies and have an excuse to unrack it and start soldering again!

One note about the power, you have to be careful not to use too thick a gauge wire. That's why the test fit has different colors than the pic with everything bolted down. 

Those blocks work with 28ga, 26ga is a squeeze so you have to get the 300V wire with the thinner jacket, and 24ga just doesn't fit. 26ga 300V is still WELL above the current draw and max voltage (48V phantom) for 8 of these, so I ended up using that. This is my first foray into Molex as I hardwire everything in my pedals and amps, so I had to learn that the hard way.

Still, once you get the hang of doubling them up so they fit in the header you can pound out the connectors for power, input, and output in an hour or less.

 

[mrclunk]

Nice work!
312's were a revelation to me too when i built some here.
Whats the red box on top? Looks fun!

 

[3nity]

Thats a dummy rack filler isnt?

Great work...congrats Mike.

I was thinking about getting some of those DI,s but im short on money this week maybe next week!

Thanks

 

[Moose]

Yeah, it's a dummy filler. Someone gave it to me years ago. It came along with the rack plate for the RNP/RNC combo. I guess it's good when you feel like you need to turn knobs for the placebo effect that physically rotating a knob gives.

That "rack" is just a wooden box that sits next to my monitor. I mix in the box, so I don't usually have a lot of outboard gear within reach. The rack normally only holds a verb and a headphone amp in addition to the 828. The pres went in for the comparison test, and I decided to plug the hole. The headphone amp is moving to a different box so I can have it closer to performers when I want to do overdubs.

The APIs are  definitely a go-to preamp, now. I can see them remaining quite useful even after I've built a few other dream pres.