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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, March 26, 2008
Wednesday, March 26, 2008 6:31:57 AM (Central Standard Time, UTC-06:00) (  |  |  )
It's done :)  My switching DC-to-DC PSU.

I've been working on this design on and off since October 2007. Several prototypes later, and many $$$, I'm happy with it.  All output voltages are regulated and adjustable via multiturn trimmers, +18, -18 and it's a true +48V phantom power... all derived from a single 12Volt input.  Outputs are short circuit protected. Just a big spark, but keeps on ticking. Nothing gets blown. 


http://farm3.static.flickr.com/2322/2365867488_5f14133bbd.jpg

Powering my preamp and my I/O module (input and output trafo, pad, polarity) with Active DI, via 12V wall wart. No hashing sound, no RF leak, no noise. (Well, okay... when you're at 66-72dB gain... but could be caused by everything not in a metal enclosure.)


http://farm4.static.flickr.com/3068/2352224005_5dc492842c.jpg


Output on all 3 rails are typical like below:

http://farm3.static.flickr.com/2376/2365001131_8b2c1a26ac.jpg

Switching spikes on the DC output of about 0.06Vpeak-to-peak, and interval of 33.333Khz. I can set switching freq. to about 60Khz but the spikes get larger.

So I compromised for smaller spikes at a lower switching frequency... i.e. smaller spike/transients, less RFI energy emitted, less chance that it will interfere with sensitive mic pre circuitry.

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