transistors for front end
This thread.
https://www.diyaudio.com/forums/solid...tp-choice.html
Sources:
https://www.utsource.net/index.aspx
https://www.taydaelectronics.com/servlet/StoreFront
Sadly the 2SC2240 and 2SA970 (npn, pnp) super-low-noise trannies in TO-92 packages no longer appear on Toshiba's Bipolar Transistors Product List, and have been designated NRND by Toshiba (Not Recommended for New Designs). [link] This means the factory is presumably still taking (large) orders, but they are destined for the dust-bin of history. FYI, last chance, B&D still has some inventory.
But, not to fear, Toshiba offers what appears to be the same (or better) die in SOT-23 packages, the 2SC3324 and 2SA1312. These are stocked by Mouser, and cost only 15 cents qty 100. Their datasheets are fairly complete, including two NF contour plots. The 1kHz plot shows the 3dB contour dropping 35 ohms at 1mA and below 20 ohms at 10mA. That corresponds to voltage noise levels e_n of 1.4, 0.75 and 0.56nV at 0.1, 1 and 10mA. Using the 100Hz plots, we can calculate that the 1/f corner frequencies are about 14Hz, 35Hz and 170Hz, not too bad.
The hn3c51F and hn3a51F dual transistors, original subject of this thread, also appear on Toshiba's official Bipolar Transistors Product List. They come in easy-to-solder SC-74 (6-pin SOT-23) packages, and apparently use the same dies as the 2sc3324 and 2sa1312. Their datasheets have the same two impressive noise-figure contour plots. But even though several years have gone past since this thread started, no distributors have picked up these parts. If we want to use them, we'll have to make a large group purchase. A standard reel is 3000 parts.
for VAS transistor 2SC3423 - recommended by Hugh
FYI, Diodes Inc. offers 4401/4403 in a SOT 363 dual configuration (NPN+NPN, PNP+PNP and NPN+PNP), the prefix for duals is MMDT and the complementary version is 4413. The same chip is also available in single SOT23 and, of course, TO92. All those parts seems to be globally available through standard channels.
https://www.diyaudio.com/forums/solid...tp-choice.html
Sources:
https://www.utsource.net/index.aspx
https://www.taydaelectronics.com/servlet/StoreFront
Sadly the 2SC2240 and 2SA970 (npn, pnp) super-low-noise trannies in TO-92 packages no longer appear on Toshiba's Bipolar Transistors Product List, and have been designated NRND by Toshiba (Not Recommended for New Designs). [link] This means the factory is presumably still taking (large) orders, but they are destined for the dust-bin of history. FYI, last chance, B&D still has some inventory.
But, not to fear, Toshiba offers what appears to be the same (or better) die in SOT-23 packages, the 2SC3324 and 2SA1312. These are stocked by Mouser, and cost only 15 cents qty 100. Their datasheets are fairly complete, including two NF contour plots. The 1kHz plot shows the 3dB contour dropping 35 ohms at 1mA and below 20 ohms at 10mA. That corresponds to voltage noise levels e_n of 1.4, 0.75 and 0.56nV at 0.1, 1 and 10mA. Using the 100Hz plots, we can calculate that the 1/f corner frequencies are about 14Hz, 35Hz and 170Hz, not too bad.
The hn3c51F and hn3a51F dual transistors, original subject of this thread, also appear on Toshiba's official Bipolar Transistors Product List. They come in easy-to-solder SC-74 (6-pin SOT-23) packages, and apparently use the same dies as the 2sc3324 and 2sa1312. Their datasheets have the same two impressive noise-figure contour plots. But even though several years have gone past since this thread started, no distributors have picked up these parts. If we want to use them, we'll have to make a large group purchase. A standard reel is 3000 parts.
for VAS transistor 2SC3423 - recommended by Hugh
FYI, Diodes Inc. offers 4401/4403 in a SOT 363 dual configuration (NPN+NPN, PNP+PNP and NPN+PNP), the prefix for duals is MMDT and the complementary version is 4413. The same chip is also available in single SOT23 and, of course, TO92. All those parts seems to be globally available through standard channels.
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