DIY-Central.com - Go Create something! - PCB Design, Electronics

Navigation

Home

DIY Mic Pre Kits

DIY Projects

Home Studio Guide

Electronics Bookstore

Home Studio Equipment List

Search

Blogroll

| |

E-mail

Total Posts: 79
This Year: 16
This Month: 1
This Week: 0
Comments: 13

SC-1 Mic Preamp NOW ON SALE!!!!

After many months of development, testing, troubleshooting, frustration, problems, and accomplishments... the SC-1 mic preamp kit, PSU-1848 power supply kit and power transformer kits are now available for sale!

Click here to ORDER

Photo of a finished SC-1 mic preamp kit! (Note: XLR jacks and wires shown on picture not included in the kit.)

Features:
- Low-Noise, transformerless, High-Quality Mic Preamp
- All solid-state design, using chipsets from THAT Corp and Burr-Brown
- Soft-start, slow ramp-on +48V phantom power
- Crystal clear Red LED indicator for phantom power
- Electronically balanced input and output stages
- 12-position Grayhill gain selector switch
- Gain range from +6 to +72dB, in 6dB increments
- Input RFI protection
- Input clamping protection
- Output surge protection circuit
- Output RFI protection
... read more...

Download PDF file of Assembly Guide/Kit Instructions

Related products like the PSU-1848 Power Supply Kit, Power Transformer Kit, Power Control Kit are also available for sale. Click here.

Wednesday, November 22, 2006

DIY API Preamp Project

Wednesday, November 22, 2006 6:16:46 AM (Central Standard Time, UTC-06:00) ( API Preamp | DIY )

Just a work in progress.... using a breadboard.

API schematics found on the Internet... just google API 312 schematic. You can see the printout of the schematic on the photo.

I'm using a Melcor Discrete opamp instead of the original 2520 opamp (which you can't buy unless you have a broken 2520 to surrender to API). Although there are many substitute opamps you can use like the Jensen 990C, Forsell Technologies 992, John Hardy opamp, etc... or if you're really scraping, just use an NE5534 IC chip.

The output transformer is a Profile transformer. The company I was told made the original 2503 output transformer for API. The last thing I heard is there is some legal battle between API and Profile over who owns the patents for the transformer design... At least that's how I understand it... so the output transformer can't be bought at the moment... (glad I got mine before all this legal brouhaha). But substitute transformers from Cinemag or Jensen can be used... maybe even Lundahls or Sowters.

Anyways, I powered my circuit and it works... lots of gain... 44+dB... 20Hz to 20Khz with nice sine wave on the oscilloscope, no distortion... measured at 10.74Vrms output voltage from an input voltage of 62 milliVolts!

Did you read that??? from 62 mV, it amplified it to 10.74Volts cleanly, from 20Hz to 20Khz. Smile

Love the sound... it sounds big. This will sound great on bass or drums... maybe vocals too, and synths.

If you can't DIY, Brent Averill sells a 312 preamp for $899 dollars. His uses Avedis™ 1122 opamps and Jensen input and output transformers. http://brentaverill.com/products/index.asp?itemnum=2

Mine costs less than $40 including output transformer, so add a Power supply and a 1u rack, I'm looking at $100. Add another $60 for a Jensen input transformer, so about $160 total. Sweet!

| Trackback |

DIY-Central.com - Go Create something! - PCB Design, Electronics

Electronics, PCB, Audio, Recording, Studio - Build, Create, Hacks

Navigation

Search

Categories

On this page

Archive

Blogroll