Hi:
What list of transistors would be suitable for building and experimenting with 80-90% of class AB audio power amp. topologies, for 1-50W output range plus basic gain/buffer stages?
Ie., some BJT (& MOSFET) complementary output pairs, drivers, low noise/high-gain types, and some low noise JFETs for inputs, or pairs for differential amps?
Note: the list needn't cover the extremes of perfection.
If for ex. 6 different amp circuits specify 3 different input transistors, one of which is very exotic but which may be substituted by either of the others for a slight loss in performance or with some minor bias adjustment, etc., and one of the remaining two is very hard to obtain, then just the one remaining, easy to get one shall suffice.
Comments and lists appreciated!
What list of transistors would be suitable for building and experimenting with 80-90% of class AB audio power amp. topologies, for 1-50W output range plus basic gain/buffer stages?
Ie., some BJT (& MOSFET) complementary output pairs, drivers, low noise/high-gain types, and some low noise JFETs for inputs, or pairs for differential amps?
Note: the list needn't cover the extremes of perfection.
If for ex. 6 different amp circuits specify 3 different input transistors, one of which is very exotic but which may be substituted by either of the others for a slight loss in performance or with some minor bias adjustment, etc., and one of the remaining two is very hard to obtain, then just the one remaining, easy to get one shall suffice.
Comments and lists appreciated!
With a little searching I suspect you will uncover several old threads that ask essentially the same question. There are a LOT of favorites for output devices. The choices for medium-power driver stages have dwindled to a few as CRT displays have vanished. I'll stick my neck out and suggest that the BC54x/BC55x family (including the BC550/BC560 low-noise devices) are usable (though not always optimum) for at least 95% of all small-signal applications. The SMT versions are BC84x/BC85x.
Dale
Dale
Thanks for the reply.
I'm considering to get a bunch of 2SC3503E and KSA1381E from Rochester, since I need the C3503 for electrostatic CRT deflection amps. I figured I might as well try to get the complements as well. Then I discovered it's quite a frequently mentioned part here.
I haven't fulfilled the min. order at Rochester yet, since they are oddly cheap (I may have to double check that they are "kosher"?), so I'll probably try to score some lower voltage ones as well if they have some of the other good performing Sanyo video output amp. equivalents.
It does seem like discrete circuit designing&building is going to get more difficult, so I'm thinking it's time to stock up now for all the projects I have planned for some day.
Yeah, that pair probably gets mentioned as much as all others combined.
Fairchild's KSC3503 version is in current production and readily available . . . in the "D" gain grade. The complementary KSA1381 is also easily obtained . . . but only in the "E" grade! I'd like to know the rationale behind THAT decision!
Dale
For BJT final output stage, the MJL3281A / MJL1302A are hard to beat.
To drive the bases of the final output stage (the "driver stage"), I like 2SC5171 / 2SA1930.
For small signal stages with low VCE (current mirrors, and anything that's been cascoded), I'm fond of BC337 / BC327.
Although it's worth pointing out that a typical vacuum tube power amp contains 6 tubes, and a typical solid state amp contains 18 transistors. So you might reasonably expect to pay (1/3rd) the price of a tube, for each transistor. (About $3 to $10 per transistor.) This kind of budget lets you purchase "exotic transistors" that scare most people away, like the SSM-2212, MAT01, THAT corporation matched pairs, LS-301 from Linear Systems, and so forth.
To drive the bases of the final output stage (the "driver stage"), I like 2SC5171 / 2SA1930.
For small signal stages with low VCE (current mirrors, and anything that's been cascoded), I'm fond of BC337 / BC327.
Although it's worth pointing out that a typical vacuum tube power amp contains 6 tubes, and a typical solid state amp contains 18 transistors. So you might reasonably expect to pay (1/3rd) the price of a tube, for each transistor. (About $3 to $10 per transistor.) This kind of budget lets you purchase "exotic transistors" that scare most people away, like the SSM-2212, MAT01, THAT corporation matched pairs, LS-301 from Linear Systems, and so forth.
Nice, a full set of pairs!
I'll check out some of those too. I discovered THAT a few years ago, whilst looking about for high CMRR (that don't go downhill immediately above 60Hz) differential input stages for instruments.
My junction transistor stock include MJ15015/16, MJ21195/96. (TO3) MJE15032/33 and TIP31C,32C,41C,42C, (TO220) MPSA06/56, MPS8099, 2n5401/5551,2n3904 (TO92 ) and J111.J112,J174, (Jfets). for protection I got a good price on FDP52n20 Nfets and I use 2n7000 nfet for low energy switching. For PFET's I laid in a few IRF5410's, to switch off the PS + rail without a separate supply if I have to. All are fairchild, ON semi or IR parts I found in stock at newark.com, from which I can get 1 to 3 day service UPS surface if the order is in by 10am for $7 . I've also bought transistors from Mouser, but they are 4 days away surface and their metal film resistors seem to be primarily Xicor. (******se)
The ON transistors tend to have a SOA spec, which considering the bad solder joints or downright wiring errors I have made in my experiments, have saved a few parts from time to time. I do use informal heat sinks (screen door frame bits) on everything that has a tab. When I smell hot grease, I feel around for heat and the parts have usually been okay after resoldering (except open base leads with 80 Vce on TO92. The TO3's on heat sinks withstood 180v with an open base lead solder joint, even while ultrasonically oscillating).
I bought a few BD139/140 last time, fairchild to see if I can hear the difference between those 100 mhz parts and the TIP41/42C 3 mhz parts I'm using in my prototype for VAS and drivers. With 14000 hz maximum ears, I doubt it.
If I was going to try plastic junction output transistors, the fairchild fjl4215/4315 looks interesting when the MJ4281/4302 parts are out of stock.
I found a bargain last month on BD639 high current TO92 transistors from ON, and some MPSW56, also from ON.
If you want to experiment with lateral complementary FET's, Newark stocks stocks the UK sourced (allegedly) ALF08N/P xx TO220 parts.
The ON semi TO3 parts (or variations, small holes) have come in made in Mexico. A good reason IMHO to drill 4 holes in a diamond instead of 3 in a row. The insulator kits with washers come from multicomp (newark) most conveniently, mouser has thermaloy hitech silicon to3 pads but no washers that I can find. One reason I don't mess with LM3886 amp IC's, you have to make the **** insulator pad yourself, if you're not going to pay $10 freight for $6 parts from some exotic one horse supplier.
On monkeys around with part numbers a lot for their new lines, which are often promotionally priced. So it is often best to use the selector table for minimum and maximum Vceo, package style, npn or pnp, and see what is in stock. 2n3904 has never been less than $.35 for on or fairchild parts whereas the higher voltage MPS8099 or MPSA06/56 or 05/55 or MPSW etc sometimes go for $.024 each. I've blown some 2n3904 in service even with good solder joints, perhaps SOA violations, so I like the tougher parts at a lower price. As far as noise, i've found and eliminated it in carbon comp resistors and tantalum caps, never in a transistor yet.
The ON transistors tend to have a SOA spec, which considering the bad solder joints or downright wiring errors I have made in my experiments, have saved a few parts from time to time. I do use informal heat sinks (screen door frame bits) on everything that has a tab. When I smell hot grease, I feel around for heat and the parts have usually been okay after resoldering (except open base leads with 80 Vce on TO92. The TO3's on heat sinks withstood 180v with an open base lead solder joint, even while ultrasonically oscillating).
I bought a few BD139/140 last time, fairchild to see if I can hear the difference between those 100 mhz parts and the TIP41/42C 3 mhz parts I'm using in my prototype for VAS and drivers. With 14000 hz maximum ears, I doubt it.
If I was going to try plastic junction output transistors, the fairchild fjl4215/4315 looks interesting when the MJ4281/4302 parts are out of stock.
I found a bargain last month on BD639 high current TO92 transistors from ON, and some MPSW56, also from ON.
If you want to experiment with lateral complementary FET's, Newark stocks stocks the UK sourced (allegedly) ALF08N/P xx TO220 parts.
The ON semi TO3 parts (or variations, small holes) have come in made in Mexico. A good reason IMHO to drill 4 holes in a diamond instead of 3 in a row. The insulator kits with washers come from multicomp (newark) most conveniently, mouser has thermaloy hitech silicon to3 pads but no washers that I can find. One reason I don't mess with LM3886 amp IC's, you have to make the **** insulator pad yourself, if you're not going to pay $10 freight for $6 parts from some exotic one horse supplier.
On monkeys around with part numbers a lot for their new lines, which are often promotionally priced. So it is often best to use the selector table for minimum and maximum Vceo, package style, npn or pnp, and see what is in stock. 2n3904 has never been less than $.35 for on or fairchild parts whereas the higher voltage MPS8099 or MPSA06/56 or 05/55 or MPSW etc sometimes go for $.024 each. I've blown some 2n3904 in service even with good solder joints, perhaps SOA violations, so I like the tougher parts at a lower price. As far as noise, i've found and eliminated it in carbon comp resistors and tantalum caps, never in a transistor yet.
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The resistor manufacturer Xicon spells their name with an N not an R.
My most recent orders of thru-hole resistors from Mouser, are pretty much evenly split between Xicon 1% metal film resistors, and Yageo 1% metal film resistors. Sometimes the value I need is in stock from one but not the other. Sometimes the value and higher-than-250mW power rating is in stock from one but not the other. I'm equally happy with the resistors from both manufacturers.
My most recent orders of thru-hole resistors from Mouser, are pretty much evenly split between Xicon 1% metal film resistors, and Yageo 1% metal film resistors. Sometimes the value I need is in stock from one but not the other. Sometimes the value and higher-than-250mW power rating is in stock from one but not the other. I'm equally happy with the resistors from both manufacturers.
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