ppl
Building amps and assuring water resistance.
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- Jun 21, 2001
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I would strongly advice you stick with the 2N5088 and 2N5087. Electrically the BC550C and BC560 will work but require rotation 180 to match pin out of the 2N devices. The 2SA1015 and its complement less suited electrically however have the base and emitter interchanged from the 2N types. See Below links to the data sheets.
2AS1015> http://www.alldatasheet.co.kr/datash...A/2SA1015.html
2SC1815> http://www.alldatasheet.co.kr/datash...A/2SC1815.html
2N5087 > http://www.alldatasheet.co.kr/datash...MI/2N5087.html
2N5088 > http://www.alldatasheet.co.kr/datash...MI/2N5088.html
BC550C> http://www.alldatasheet.co.kr/datash...LA/BC550B.html
BC560C> http://www.alldatasheet.co.kr/datash...LA/BC560C.html
BC337> http://www.alldatasheet.co.kr/datash...OLA/BC337.html
BC327> http://www.alldatasheet.co.kr/datash...OLA/BC327.html
MPS8099> http://www.alldatasheet.co.kr/datash...A/MPS8099.html
MPS8599
The selection of the 2N5087&2N5088 transistors was primarily based upon creating the ideal devices for use in the current Mirrors; however the high bandwidth and extremely high Gain at very low collector currents proved to provide a more stable buffer when operated at low quiescent currents, Moreover the low noise figure of These transistors have been used in the past in High gain Microphone and Magnetic phono preamps in both high end Equipment such as Mc-Intosh Preamplifiers and power amplifiers in addition to Mark Levenson. The low noise figure of 2-3 dB typical for the 2N5087&2N5088 are one of the primary reasons for there use in high gain low noise Audio circuits. Anyone that thinks these devices are not suitable for audio use or popular should perhaps look into this further
The PN4392-PN4393 as well as the MPF4392-MPF4393 will interchange just fine. The Bias adjustment makes some tolerance on this transistor possible as long as the device you select has a min Idss of 30mA and your not looking at setting the output bias at 40 or so mA then things will be ok. Matching transistors are not mandatory however lower DC offset and perhaps better sound with slight measurable Right mark performance will be obtained with matched devices. The output transistors should all be matched in all three channels because of the symmetry created by the ground channel with respect to the right and left channel.
The output transistors allow some considerable flexibility. The default MJE243/253 provide the best solution for low impedance headphones as thay are of considerably higher current than the BD139 and BD140. However the BD139/140 pair have higher bandwidth with an ft of 190 typical vs 40 typical for the MJE243/253 at high currents the Hfe falls quicker on the 139/140 pair than the Mje’s so for low impedance headphones the Mje243 and 253 provide greater high frequency because the Hfe hold up better because of the higher current capacity of the devices. This is the paradox of BJT output transistor selection more power less fast devices. This is accounted for by providing driver transistors that have bandwidths of over 300 MHz at the currents they are operated at in the PPA v 2.0. However for you speed demons I might suggest the flowing transistors as output devices mind you the maximum short circuit current of these faster devices will be about 1 amp for a few seconds.
BD139/140> http://www.alldatasheet.co.kr/datash...IPS/BD139.html
KSA1220> http://www.alldatasheet.co.kr/datash...D/KSA1220.html
KSC2690> http://www.alldatasheet.co.kr/datash...D/KSC2690.html
2SC3421> http://www.alldatasheet.co.kr/datash...A/2SC3421.html
2SA1358> http://www.alldatasheet.co.kr/datash...A/2SA1358.html
The BD787/788 and the MJE 243/253 provide the best all around performance with load impedances lower than 50 ohms at bias currents above 20 mA throught the output transistors emitter resistor. Lower bias currents and or higher load impedances generally favor the lower current higher speed devices.
BD787/788> http://www.alldatasheet.co.kr/datash...OLA/BD788.html
MJE243/253> http://www.alldatasheet.co.kr/datash...LA/MJE243.html
2AS1015> http://www.alldatasheet.co.kr/datash...A/2SA1015.html
2SC1815> http://www.alldatasheet.co.kr/datash...A/2SC1815.html
2N5087 > http://www.alldatasheet.co.kr/datash...MI/2N5087.html
2N5088 > http://www.alldatasheet.co.kr/datash...MI/2N5088.html
BC550C> http://www.alldatasheet.co.kr/datash...LA/BC550B.html
BC560C> http://www.alldatasheet.co.kr/datash...LA/BC560C.html
BC337> http://www.alldatasheet.co.kr/datash...OLA/BC337.html
BC327> http://www.alldatasheet.co.kr/datash...OLA/BC327.html
MPS8099> http://www.alldatasheet.co.kr/datash...A/MPS8099.html
MPS8599
The selection of the 2N5087&2N5088 transistors was primarily based upon creating the ideal devices for use in the current Mirrors; however the high bandwidth and extremely high Gain at very low collector currents proved to provide a more stable buffer when operated at low quiescent currents, Moreover the low noise figure of These transistors have been used in the past in High gain Microphone and Magnetic phono preamps in both high end Equipment such as Mc-Intosh Preamplifiers and power amplifiers in addition to Mark Levenson. The low noise figure of 2-3 dB typical for the 2N5087&2N5088 are one of the primary reasons for there use in high gain low noise Audio circuits. Anyone that thinks these devices are not suitable for audio use or popular should perhaps look into this further
The PN4392-PN4393 as well as the MPF4392-MPF4393 will interchange just fine. The Bias adjustment makes some tolerance on this transistor possible as long as the device you select has a min Idss of 30mA and your not looking at setting the output bias at 40 or so mA then things will be ok. Matching transistors are not mandatory however lower DC offset and perhaps better sound with slight measurable Right mark performance will be obtained with matched devices. The output transistors should all be matched in all three channels because of the symmetry created by the ground channel with respect to the right and left channel.
The output transistors allow some considerable flexibility. The default MJE243/253 provide the best solution for low impedance headphones as thay are of considerably higher current than the BD139 and BD140. However the BD139/140 pair have higher bandwidth with an ft of 190 typical vs 40 typical for the MJE243/253 at high currents the Hfe falls quicker on the 139/140 pair than the Mje’s so for low impedance headphones the Mje243 and 253 provide greater high frequency because the Hfe hold up better because of the higher current capacity of the devices. This is the paradox of BJT output transistor selection more power less fast devices. This is accounted for by providing driver transistors that have bandwidths of over 300 MHz at the currents they are operated at in the PPA v 2.0. However for you speed demons I might suggest the flowing transistors as output devices mind you the maximum short circuit current of these faster devices will be about 1 amp for a few seconds.
BD139/140> http://www.alldatasheet.co.kr/datash...IPS/BD139.html
KSA1220> http://www.alldatasheet.co.kr/datash...D/KSA1220.html
KSC2690> http://www.alldatasheet.co.kr/datash...D/KSC2690.html
2SC3421> http://www.alldatasheet.co.kr/datash...A/2SC3421.html
2SA1358> http://www.alldatasheet.co.kr/datash...A/2SA1358.html
The BD787/788 and the MJE 243/253 provide the best all around performance with load impedances lower than 50 ohms at bias currents above 20 mA throught the output transistors emitter resistor. Lower bias currents and or higher load impedances generally favor the lower current higher speed devices.
BD787/788> http://www.alldatasheet.co.kr/datash...OLA/BD788.html
MJE243/253> http://www.alldatasheet.co.kr/datash...LA/MJE243.html