So, which BJT, FET, MOSFET to choose for new designs in 2011?
Discretes seems to be more difficult to source and prices are astronomic in some special cases.
Future availability must be considered.
It is interesting to find alternatives to those classis audio transistors, often something else can be used, and still give similar performance.
Exotic transistors are fun, but it is better to design around devices that are widely used and as such has lower cost and is more likely to be around in the future.
As for performance, it is often a matter of circuit design.
Here is a list of some transistors for audio use:
Small signal:
BJT BC550(C), BC560(C) (Good, but limited VCE)
BJT Toshiba 2SA970, 2SC2240 (future availability?)
BJT ROHM 2SB737, 2SD786 (Not found in current ROHM catalog)
FET 2SK170, 2SJ74 (possible to find, future availability?)
FET 2SK146, 2SJ72 (Only found in my spare parts bin..)
Driver, line output:
BJT Toshiba 2SA1358, 2SC3421 (future availability?)
BJT Toshiba 2SA1837, 2SC4793 (future availability?)
BJT BD139, BD140 (mediocre performance, but ok in many applications)
MOSFET Hitachi 2SK213(->2SK216), 2SJ76(->2SJ79) (Now made by Renesas, difficult to source, horrible prices)
MOSFET IRF510 (Suggested replacement for 2SK213+++, but it is not the same..)
Power:
BJT Toshiba 2SA1943, 2SC5200 (Easy to find, ok prices, future availability?)
Recommendations and other relevant input on the selection of especially small-signal and driver BJT & FET is highly appreciated.
Discretes seems to be more difficult to source and prices are astronomic in some special cases.
Future availability must be considered.
It is interesting to find alternatives to those classis audio transistors, often something else can be used, and still give similar performance.
Exotic transistors are fun, but it is better to design around devices that are widely used and as such has lower cost and is more likely to be around in the future.
As for performance, it is often a matter of circuit design.
Here is a list of some transistors for audio use:
Small signal:
BJT BC550(C), BC560(C) (Good, but limited VCE)
BJT Toshiba 2SA970, 2SC2240 (future availability?)
BJT ROHM 2SB737, 2SD786 (Not found in current ROHM catalog)
FET 2SK170, 2SJ74 (possible to find, future availability?)
FET 2SK146, 2SJ72 (Only found in my spare parts bin..)
Driver, line output:
BJT Toshiba 2SA1358, 2SC3421 (future availability?)
BJT Toshiba 2SA1837, 2SC4793 (future availability?)
BJT BD139, BD140 (mediocre performance, but ok in many applications)
MOSFET Hitachi 2SK213(->2SK216), 2SJ76(->2SJ79) (Now made by Renesas, difficult to source, horrible prices)
MOSFET IRF510 (Suggested replacement for 2SK213+++, but it is not the same..)
Power:
BJT Toshiba 2SA1943, 2SC5200 (Easy to find, ok prices, future availability?)
Recommendations and other relevant input on the selection of especially small-signal and driver BJT & FET is highly appreciated.
Fairchild devices - KSA992/KSC1845 for small signal, KSA1381/KSC3503 for VAS, KSA1220/KSC2690 as small drivers, FJP1943/FJP5022 as TO-220 drivers.
They also have their own TO-264 package 2SA1943/2SC5200 clones called FJL4215/FJL4315, and TO3P packaged versions FJA4213/FJA4313
Onsemi have good output and drivers... and now that they bought Sanyo I belive they make 2SA1209/2SC2911 which are good VAS devices
They also have their own TO-264 package 2SA1943/2SC5200 clones called FJL4215/FJL4315, and TO3P packaged versions FJA4213/FJA4313
Onsemi have good output and drivers... and now that they bought Sanyo I belive they make 2SA1209/2SC2911 which are good VAS devices
I'm interested in a response, too. I've finally committed to building a Borbely DC-102, and have discovered that pretty much all of the interesting transistors are obsolete and hard to find.
I just ordered the hard to find parts through eBay, a DIY member here, and other vendors. However, the JFETs in particular are so limited in availability that there is no real guarantee of receiving original devices sufficiently close in characteristics. These is not a cheap bet, either. I doubt these parts were ever cheap, but the totals start to get my attention.
My sense is that designs with complementary JFET input sections are no longer feasible, and this type of project I'm doing will be effectively impossible shortly. So, it seems that new designs will probably need to use complementary BJT's or opamps. I've noticed that some of the newer posts here discuss non-complementary BJT-based input sections.
Regards,
Rob
Here is the list of devices from Bob Cordell's site for which they have developed accurate SPICE models. It represents quite a good selection for me and I tend to stick to these when cooking up something new.
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just took a look on Toshiba's website. although they show A1934 and C5200 as current production, they have an improved pair. A2121 and C5949
Nice, prices are good too, this can be a good option for SS power amplifier.
Seems the 2SA1943/2SC5200 is widely used in PA-amps, and probably also for a lot of hifi-amps - which means supply should still be good for a while.
The problem is that class-D will make these obsolete for all but some special audiophile class-A stages.
Then other examples mentioned are good input and noted, now I will search Toshiba to find some driver/medium-power BJTs.
Seems the 2SA1943/2SC5200 is widely used in PA-amps, and probably also for a lot of hifi-amps - which means supply should still be good for a while.
The problem is that class-D will make these obsolete for all but some special audiophile class-A stages.
Then other examples mentioned are good input and noted, now I will search Toshiba to find some driver/medium-power BJTs.
semelab
MG6333W SEMELAB 260V 30A 50 400W 35MHz TO264 NPN
MG9413W SEMELAB 260V 30A 50 400W 35MHz TO264 PNP
HI GREETINGS anyone used these transistors
warm regards
andrew lebon
MG6333W SEMELAB 260V 30A 50 400W 35MHz TO264 NPN
MG9413W SEMELAB 260V 30A 50 400W 35MHz TO264 PNP
HI GREETINGS anyone used these transistors
warm regards
andrew lebon
http://www.profusionplc.com/images/data%20sheets/mg6333w.pdf
Those are big. 😱 Could not run them efficiently in a EF2 , similar to the 21193/4 Hfe-Ic plot.
Hard to get , only 1 hit on google. They would work in any well designed triple EF. Better to "double up" on NJW0281/0302 ($1.90USD) 😀 or the sanken130-150w lineup (2sa1294/2sc3263)
OS
Those are big. 😱 Could not run them efficiently in a EF2 , similar to the 21193/4 Hfe-Ic plot.
Hard to get , only 1 hit on google. They would work in any well designed triple EF. Better to "double up" on NJW0281/0302 ($1.90USD) 😀 or the sanken130-150w lineup (2sa1294/2sc3263)
OS
Here's one I do believe .... http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00171942.pdf
225W , but with an SOA that beats the TO-3 MJ21193/4. These I can source easily.
#1 Killer BJT output ! (6A /60V/100mS SOA)
OS
225W , but with an SOA that beats the TO-3 MJ21193/4. These I can source easily.
#1 Killer BJT output ! (6A /60V/100mS SOA)
OS
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Hi
I'm probably out of the loop here in saying but IMHO the best output transistors are vertical mosfets. Unfourtunately most people don't use the advantages they provide, being very high Ft, high current gain, subtantial SOAR, and cheap price. IMO vertical fets require some sort of local fb or EC to achieve these goals while keeping distortion low. A lot of folks scoff at the idea of adding 4 or 8 or even more if you choose to cascode😀 the driving stage transistors into the circuit just for the output stage.
In addition there becomes an issue with layout/compensation and instability/limits of the circuit. If your willing to go to the trouble of detail, I think they have the potential to make great output stages.
I'm probably out of the loop here in saying but IMHO the best output transistors are vertical mosfets. Unfourtunately most people don't use the advantages they provide, being very high Ft, high current gain, subtantial SOAR, and cheap price. IMO vertical fets require some sort of local fb or EC to achieve these goals while keeping distortion low. A lot of folks scoff at the idea of adding 4 or 8 or even more if you choose to cascode😀 the driving stage transistors into the circuit just for the output stage.
In addition there becomes an issue with layout/compensation and instability/limits of the circuit. If your willing to go to the trouble of detail, I think they have the potential to make great output stages.
It seems better make the designs less critical for transistor parameter, so that it is easy to change to other types.
Sufficiently good small signal, driver and output BJTs should be possible to find.
Problem is, when you design for FETs, you need a FET not that far away from then original spec.
Also, when pushing limits, such as VCE requirements, it can be more difficult to find alternatives.
Low feedback designs will generally be more critical as well.
Sufficiently good small signal, driver and output BJTs should be possible to find.
Problem is, when you design for FETs, you need a FET not that far away from then original spec.
Also, when pushing limits, such as VCE requirements, it can be more difficult to find alternatives.
Low feedback designs will generally be more critical as well.
I use the IRFP240/9240 quite a lot.
Good beefy large output transistors which are easy to drive.
East to source and relatively cheap.
Good beefy large output transistors which are easy to drive.
East to source and relatively cheap.
i've been repairing current production Denon, Yamaha, Marantz, Onkyo, and Pioneer receivers, and only Pioneer makes a high-end receiver with class-D amps. Pioneer still makes class-AB amps as well. The others are still making almost exclusively class-AB amps, so i don't think linear amps are going to be going away any time soon. Pioneer's amps use Bang&Olufsen ICE amp chips, but at the same time, they still are making new designs with AB amps as well. so i think the AB amp still has a place in audio, and will continue to for a long time. even in Pioneer's class D receiver, they still use "big iron" in the power supply. most other manufacturers out there are still developing AB amps, and D amps are usually used in low end stuff like Panasonic and Samsung home theater all-in-one units. the only real reason they're in use in that application is miniaturization, not performance. so it's in small and midsize stuff that D amps have any real impact. the only other place D amps are used much is in a few PA amps (like Peavey's ultralights), but companies like QSC still have AB amps (with switching supplies) in their ultralights. for one thing, it's difficult and expensive to get a D amp to use negative feedback. without the negative feedback the amp doesn't have a good damping factor, which makes it sound different.
I agree with respect to lateral fets. An optimally designed vertical fet output stage would have some sort of local feedback(feedforward) EC and would be less picky about the particular device. Parameters that are important to match with a replacement here would be realative Gm, Vds, and CISS (particularly in the case of a SF Cgd).
So, might be better to design using SMD devices - there should be no advantage using the old TO92.
BC550/560 and C2240 will be easy to find in SMD, but are there small-signal FETS like the 2SK170, 2SJ74 available in new SMD types?
BC550/560 and C2240 will be easy to find in SMD, but are there small-signal FETS like the 2SK170, 2SJ74 available in new SMD types?
Yes, I agree that this is the situation as for today.
But I still think class-D will take over more and more, and especially for the pro market this newer technology gives great performance advantages and lower cost per watt output power.
Class-D is becoming more and more mainstream while performance is getting better and cost is getting lower.
This should mean that semiconductor development will focus more on switching devices and less on low-noise and linearity.
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