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CA-0252 Built Kit

Original price $50.00 - Original price $50.00
Original price
$50.00 - $50.00
Current price $50.00

The CA-0252-DIY is not the same circuit as the gar2520. Gary's version is 9 transistors with a resistive current source for the input transistor long-tailed pair. The CA-0252-DIY is a 10 transistor circuit with a transistor current source for the long-tailed pair. 

Input transistors
The OG input transistor pair were BC414Cs. In researching these parts, I found BC237C to be the recommended replacement. So, due to supply issues, we chose to use BC237Cs for these. To our ears they were closer to the OG than the commonly used BC550C etc.

Interstage NPNs
The OG was TIS98 for these 3 transistors. We have been using Fairchild TIS97s for our BT50s so decided to stick with them for this situation. Since TIS97s are long out of print and very hard to find, we had them custom made by a US manufacturer. Its actually amazing that can still be done!

Interstage PNPs
The OG was 2N5087 for these 3 transistors. I was able to procure a mother-load of NOS National Semiconductor 2N5087s so that is what we are using. They definitely sound different than the more recent Fairchild or ON Semi stock.

Output Transistors
The OG output transistor pair were metal can TO-39s, specifically BC141-16 and BC161-16. These are unobtainium and have been for years. We tried the Multicomp version and found them lifeless so we had them custom manufactured like the TIS97s. They are outstanding parts and a very big part of the tone.

The CA-0252-DIY only ships with the longer terminal pins so there is no issue in a 2500 etc that may have other components under the opamp footprint. These longer pins impose no issues when used in a situation with no components under the amp. Just leave them long. If you have an old school situation where the amps are soldered directly to the PCB, just solder them in and cut the pins off.

Some of the applications the CA-0252-DIY DOA can be used for:
 Microphone Preamplifiers
 Line or Booster Amplifiers
 Lossless Combining Amplifiers
 Balanced Transformerless Amplifiers
 Equalizers and Compressors

Additional features and specs:
 Industry standard 2520 footprint for plug-in or PC mount connections
 Low noise, high power output
 Low distortion
 Minimum load impedance is 75 ohms for full output voltage
 Power supply voltage is bi-polar +/- 12 VDC to +/- 20 VDC