Few denon amps (PMA series) (and may be few earlier Marantz) use Motor Driver transistor 2SD2083 and its complimentary.
Data sheet here : https://www.semicon.sanken-ele.co.jp/sk_content/2sd2083_ds_en.pdf
my question is
are there any pros and cons using such industrial Darlington transistors ?
thanks.
Data sheet here : https://www.semicon.sanken-ele.co.jp/sk_content/2sd2083_ds_en.pdf
my question is
are there any pros and cons using such industrial Darlington transistors ?
thanks.
Thanks gentlemen.
I understand without schematics and load it will be driving is not known.
1) Resistors : resistors are 2k and 100 ohms.
2) High Gain : Any advantage of having high gain as modern sources give more than enough output volts. More Noise ?
3) fT : the data sheet says 20Mhz.
4) CoB : 340pf how important it is ?
all above good enough ?
I guess being driver for motor these may probably have been choosen for durability ? and High gain to have simple class AB circuit ?
Please be gentle newbie here.
regards.
Why, you want to make an amp or repair one?
There may be articles on the use of these transistors in general, and specific for audio.
2 dies in one housing, each with gain of 30, gives 30 x 30 = 900 gain, may have to modify circuits big time.
There are other options for making amplifiers, and Denon and Marantz were complex circuits, using very close tolerance parts.
Difficult to duplicate.
There may be articles on the use of these transistors in general, and specific for audio.
2 dies in one housing, each with gain of 30, gives 30 x 30 = 900 gain, may have to modify circuits big time.
There are other options for making amplifiers, and Denon and Marantz were complex circuits, using very close tolerance parts.
Difficult to duplicate.
If you want to build an EF2 output stage, you are better off connecting to driver emitters through one shared resistor rather than tying each one to the output. This will give you better performance in the crossover region as the active transistor gets more of the available voltage, and the non-active one gets the reverse charge pulled out more quickly. With the 100 R resistor here, you cannot do this, and what is worse, you have excluded the typical 0.22 R output transistor emitter resistor from the local feedback loop.
The other thing about Darlingtons, when you compare the hfe vs IC curve to the curve of a discrete darlington made up of any half-decent extended beta driver and output transistor, the discrete darlington will be a lot more linear. I have no idea why darlingtons always underperform in this area.
The other thing about Darlingtons, when you compare the hfe vs IC curve to the curve of a discrete darlington made up of any half-decent extended beta driver and output transistor, the discrete darlington will be a lot more linear. I have no idea why darlingtons always underperform in this area.
No. This is out of curiosity.
Just finished LM1875 amp need to implement tone boards casing etc. is remaing. Apart from that I am not repairing or building anything.
The reason they ‘underperform’ in the hFE-IC curves is because of that non-optimal resistor connection. It steals base current, so the curve doesn’t look so good - rolling off hard at low current because there isn’t enough voltage to turn both on. Bias up at a reasonable current and linearity is reasonable. All monolithic darlingtons do this.
These particular parts aren’t especially rugged for audio. Not horrible, but not as ‘good’ as real audio transistors like their LAPT types. They are a run of the mill triple diffused type, which is Toshiba’s domain, not Sanken’s. Linear SOA is rather ho-hum, with the second breakdown breakpoint at only 30V. The only thing special about them is the high current capability. Higher than the typical audio type. They would have advantage over the more usual audio types at low impedance and low voltage, not a combination you typically run into.
These particular parts aren’t especially rugged for audio. Not horrible, but not as ‘good’ as real audio transistors like their LAPT types. They are a run of the mill triple diffused type, which is Toshiba’s domain, not Sanken’s. Linear SOA is rather ho-hum, with the second breakdown breakpoint at only 30V. The only thing special about them is the high current capability. Higher than the typical audio type. They would have advantage over the more usual audio types at low impedance and low voltage, not a combination you typically run into.
Look at that. Out off curiosity.
https://www.diyaudio.com/community/threads/ab100-class-ab-power-amplifier.227503/
That's a good explanation why they underperform. But why have those resistors in the first place rather than having the designer chose what values to use and how to connect? Even if they keep the parts count low in typical motor or relay driver applications, why do designated audio darlingtons have them, too?
Back around 1970 or so I made a number af amplifiers using Motorola's MJ2501/3001 and later on its bigger brother 2N6284/6287. They worked fine at the time. The schematic came from a Motorola application note. 50 to 100 watts with only 7 transistors. They sounded fine for the time. I made a couple of tri amped mono blocks with those old parts. I still have them in the basement. I haven't turned them on in years though.
Here's the Motorola app note referred to in post #11. It was an inspiration for me in my student days.
https://conradhoffman.com/papers_lib/AN483B.pdf
https://conradhoffman.com/papers_lib/AN483B.pdf
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95% of the audio power amps I have seen used about 100 Ohms for R2. Most did not have, but would not mind, R1 at 2k.
The point about returning comp-pair base resistors to the other side is valid but kinda recent, last 30 years? Certainly "plays well" amps were built without that topology.
In the best of times I would not use these for-purpose parts. But times are tough.
Any gueses how much biasing is proper for such darlington transistor shown in #8 ?
A little offtopic.
Marantz/Denon/Yamahas are very popular in India. Marantz being at top. And unconfirmed reports is main dealers talk of importing 100/300 amps per brand/models depending on popularity (probably annualy) I wonder how much the whole world figures are per year ? How much any company would have saved by using such part ?
regards
A little offtopic.
Marantz/Denon/Yamahas are very popular in India. Marantz being at top. And unconfirmed reports is main dealers talk of importing 100/300 amps per brand/models depending on popularity (probably annualy) I wonder how much the whole world figures are per year ? How much any company would have saved by using such part ?
regards