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Building a DIY 1176 Compressor - Part 3
Building a DIY 1176 Compressor - Part 2
DIY: Building an 1176 Compressor

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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.

 Monday, December 25, 2006
Tuesday, December 26, 2006 12:08:36 AM (Central Standard Time, UTC-06:00) (  |  )
Just an update of my build: Click here to read Part 2.

Soldered 90% of the parts, including the Lundahl transformers, JFETS and transistors. I'm awaiting some parts that were "out of stock" from my first order.

Also, I ordered some wire assemblies with male/female jacks. I'll use them for connections between the main board and xlr jacks, pots, switches, etc... that way, if I need to troubleshoot the board, I can just unhook them instead of desoldering the wire from the board.



TIP: Before you complete assembly of your project, have a suitable chassis ready for it. From my experience, if I built a project without finishing the chassis first, that project becomes half-finished, working but not in a case. Laziness I know...

Also, if everything is in a chassis, you can wire everything and not have to worry about your solder connections or wires becoming loose. Everything is already in place, plus it makes it easier to work on it.

You can get your rack chassis, from 1u, 2u, all the way to 4u and 8u at par-metal.com.  They've got good prices and have nice quality racks.
 Thursday, December 07, 2006
Friday, December 08, 2006 2:04:03 AM (Central Standard Time, UTC-06:00) (  |  |  )
Just a continuation of the saga of building my 1176 clone compressor/limiter. Click here for Part 1

Parts arrived a few days ago, and other than the audio input and output transformers and chassis, I think I have enough parts to build (2) units. Here are some pics...

First, we have the output LL5402 Lundahl transformer and the LL1540 input transformer. Made in Sweden.  These things are small.



I got most of the capacitors and the power transformer at digikey.com. They have good prices for these components.




The rest of the parts like the pots, resistors, and ceramic/mylar parts came from Mouser.com. It's a big pile!







I'll clear up my work area and maybe this Christmas break, I'll be able to start construction.  Oh yeah, need to order some 2u case from Par-Metal.com.  I only have spare 1u cases in my workshop at the moment.

We're ready to build the 1176!

 Saturday, November 25, 2006
Saturday, November 25, 2006 9:08:05 PM (Central Standard Time, UTC-06:00) (  |  )
I haven't DIY'ed for a long time, so to kickstart this hobby again, I decided I'm going to build an 1176 Compressor.

The 1176 is one of the classic compressors in used by almost every recording studio out there. (The other classic compressor is the LA-2A). Bill Putnam designed the 1176, based on the 1108 preamp. Back in 1966, the Field Effect Transistor (FET) was just developed and he's experimenting with the properties of this new device. Basically, think of an FET as a "voltage controlled variable resistor."  The FET has three terminals. Drain, Source, and Gate. The resistance between the Drain and Source can  be varied/controlled by the Gate voltage. So what Mr. Putnam was doing with the FET is using it as a variable resistor to contorl the gain reduction in the circuit.

The output stage of the 1176 is a Class A line level amp, feeding a load of 600 ohms. It's got an output transformer which converts the output from unbalanced to balanced, and also do impedance matching. 

If you don't know or don't want to DIY, you can buy an 1176LN (for Low Noise) compressor for about $1800. Or, you can purchae "virtual" 1176 plugins from $130 to $225 price range. Click here for software plugin versions of the 1176.


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