Type (API) 312 Preamp Completed - Pics

[Greg]

Here are some pictures of my "Type 312" preamps using Fabio Bauman's PCBs. Just a few comments on the build:

- Jensen JT-110K-HPC input transformers
- Profile 4804 output transformers
- API 2520 opamp (Huntington, NY) on channel #1
- Melcor 1731 clone on channel #2
- DI and line input options
- external PSU

I completed these a few months ago, and they sound great. I did comparisons witht he API 3124 and the API 512. I definitely preferred the clones over the API 512, but they were similar to the API 3124. Last week I did some blind tests between the API 2520 channel and Melcor 1731 channel at a mastering facility. We used mono audio and swapped back and forth between the two channels at the same volume. The differences weren't drastic, but there was definitely a difference. The Melcor seemed to have a nice bloom in the midrange that was great for acoustic and softer material. But for rock or more aggresive type music, the API was my preference.

Special thanks to Fabio for his hard work on these boards... you rock !!!

Some pictures of the completed project:
http://members.cox.net/capstanrecording/API/312_All.JPG

http://members.cox.net/capstanrecording/API/312_Front.JPG

http://members.cox.net/capstanrecording/API/312_Top1.JPG

http://members.cox.net/capstanrecording/API/312_Top3.JPG

http://members.cox.net/capstanrecording/API/PSU_Top.JPG

 

[Greg]

It appears that the other thread is messed up... I don't know what happened. So I posted again.

 

[maxwall]

Great looking API box


Where did you get the output TX's ?

How did you do the artwork on front panel ?

What caps did you choose ?

to many questions.........

 

[Flatpicker]

Looks great! Thanks for posting the pics and the info. Could you add a connector to the PSU to power another one without over taxing the supply (Or just make a pig-tail for 2 units)? Also, I like adding a switch for switching between mic/line. I've seen "insert" jacks go flakey.

 

[Scenaria]

somethings wrong!

your bench is too clean

:green:

 

[MikoKensington]

Nice damn box there mister! That looks great. Was it you that made a BOM for this project?

 

[AnalogPackrat]

Nice one, Greg! Looking forward to building a pair of Fabio's 312s myself. Thanks also for the info comparing 1731 to 2520.

:guinness:

Analog Packrat

 

[Greg]

[quote author="maxwall"]Where did you get the output TX's ?[/quote]
I bought them directly from Profile Electronics before all the crap-o-la started between them and API. I had six at one time, but sold the extra four. I've been kicking myself ever since.

[quote author="maxwall"]How did you do the artwork on front panel ?[/quote]
I did it in the front panel software. I had it engraved by Front Panel Express. I think it cost $25 bucks or so... can't remember exactly.

[quote author="maxwall"]What caps did you choose ?[/quote]
I used Panasonics... NHG series in the PSU. FC for filtering on the main PCB. I used Panasonic B series polyesters as well as Panasonic ceramics.

[quote author="Flatpicker"]Could you add a connector to the PSU to power another one without over taxing the supply (Or just make a pig-tail for 2 units)? [/quote]
I built the PSU external for that reason. However, the 5V regulator get really hot even for two 312s. If I added another pair, I'd probably have to do some tweeking so it won't burn up.

[quote author="Scenaria"]your bench is too clean[/quote]
My bench is in rare form. Because of the f'ing sl*t Katrina, I had to move my "Lab" from apartment to my workplace. If I post a picture in a month it'll be nice and cluttered !!!

[quote author="Miko"]Was it you that made a BOM for this project?[/quote]
Fabio posted the original BOM, but I made a spreadsheet with the parts I used on it. My name is at the bottom.

Sheesh - Too much quoting...

 

[Mike Keith]

where did you get the chassis?

 

[Greg]

www.par-metal.com

I believe it's the 19082B. I replaced the stock mounting handles with black hex bolts.

 

[CJ]

Nice scope!
Good to see your back in bussiness!!

 

[Greg]

Yea that scope does the job !!! I'ts got some useful features, but I still wish I had an analog scope as well.

What's sitting on top the scope is even better. I'm racking that for friend... muhaha :thumb: .

 

[smallbutfine]

EQ? what type (can't tell it from seeing?)

:grin:

 

[smallbutfine]

BTW: Your AP*I box ROCKS! :guinness: :thumb:

 

[MikoKensington]

Calrec? Hmmm?

 

[Greg]

Yup, it's a Calrec module... :thumb: Preamp and EQ.

I just tested a Neve 1272 prototype using Fabio's re-drawn BA283AV and the JLM Audio Hotrod Mod. It's point-to-point with the exception of BA283AV. Everything looks great on the scope. I need to get it into my studio and run some audio through it. Woohoo today is a good day !!! :green:

 

[smallbutfine]

You don't waste any time, do you?

:thumb: :thumb: :thumb:

Party on!

Martin

 

[Greg]

haha... well I finished these APIs a while ago. I was working on the Neve's just before Katrina. :thumb:

 

[quadwould]

Nice work Greg. and nice bench too.

you got the Calrec and a G*SSL pcb all right there as well. you really dont waste any time do you... :thumb:

 

[Zee1usa]

Sweet ! I bet they sound wonderful. Nice work.

Hope your studio survived the flooding/looting. Sorry to hear about your parents home, families homes, studio and interuption of your life. I hope things are looking better Greg.

Take Care,

Z