I have few doubts regarding the Exicon Lateral Mosfets ECW20N20-Z
1. Is one pair of output sufficient to deliver as much as 150W in 8 ohm?
2. Absence of Gate zener diode means very easy to get damaged or degrade performance?
3. Planning to use it in class A as well so does the distortion performance be better than Hexfets for Bias of 1A per FET?
4. Why many are not using Exicon Mosfets in their designs? Is it expensive or sonically not as good?
5. Are these Mosfets are sonically the best ones outside provided in the same circuit if we use 5200 1943 / IRFP240 / ECW20N20-Z does the Exicon performs the best of all?
1. Is one pair of output sufficient to deliver as much as 150W in 8 ohm?
2. Absence of Gate zener diode means very easy to get damaged or degrade performance?
3. Planning to use it in class A as well so does the distortion performance be better than Hexfets for Bias of 1A per FET?
4. Why many are not using Exicon Mosfets in their designs? Is it expensive or sonically not as good?
5. Are these Mosfets are sonically the best ones outside provided in the same circuit if we use 5200 1943 / IRFP240 / ECW20N20-Z does the Exicon performs the best of all?
Why ask (1.) if you intend to follow (3.)? Lateral fets typically have gate-source protection diodes built in. Laterals differ in Gm from IRFhexfets. They also differ in temperature coefficient and transfer. The latter is why many choose to use lateral fets for audio power output. 🙂
1. Yes, but they won't be sufficient for 4 ohms loads and will need a big heatsink. This is because their transconductance (ability to pass current) is low and their on resistance is high. It would not be a good design.
2. HEXFETs don't tend to have gate zeners either so just take precautions when working with any FETs.
3. They are more linear than HEXFETs so may have a small improvement in performance.
4. Because they are expensive and inefficient. So not only do you need more for the same job, but your power supply needs to have higher voltage to make up for the losses in the output devices. And you need a bigger heatsink. All this adds to the cost not to mention size and weight of the unit.
5. You cannot generalise like that, the specific circuit needs to be considered. For example many people design MOSFET amps with no driver stage after the VAS, you cannot simply drop 2SC5200/2SA1943 in that application.
2. HEXFETs don't tend to have gate zeners either so just take precautions when working with any FETs.
3. They are more linear than HEXFETs so may have a small improvement in performance.
4. Because they are expensive and inefficient. So not only do you need more for the same job, but your power supply needs to have higher voltage to make up for the losses in the output devices. And you need a bigger heatsink. All this adds to the cost not to mention size and weight of the unit.
5. You cannot generalise like that, the specific circuit needs to be considered. For example many people design MOSFET amps with no driver stage after the VAS, you cannot simply drop 2SC5200/2SA1943 in that application.
I used the Exicon lateral MOSFETs many years ago in my first hi-fi amp build. The ECW20N16 IIRC.
They worked fine, but as stated above, they're not the most efficient or lowest distortion solution. I used two pairs running off +/-55V rails, and I got about 110W into 8 ohms and 160 into 4.
As for the sound, I think to get low distortion you need to bias them really hot. I found myself faced with a choice between fan noise and a slightly funky crossover-y sound at low levels.
I used the MJL3281/1302 type BJTs from OnSemi for my next build. I would say they are the best all-round solution for an output stage.
They worked fine, but as stated above, they're not the most efficient or lowest distortion solution. I used two pairs running off +/-55V rails, and I got about 110W into 8 ohms and 160 into 4.
As for the sound, I think to get low distortion you need to bias them really hot. I found myself faced with a choice between fan noise and a slightly funky crossover-y sound at low levels.
I used the MJL3281/1302 type BJTs from OnSemi for my next build. I would say they are the best all-round solution for an output stage.
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i dont know how many commercial amplifiers uses Exicon Mosfets but my question is fairly straight forward where I have a choice to choose either toshiba 5200 1943 or sanken 1216 or Exicon Lateral mosfets so provided irrespective of cost or any other parameters I would like to know which ones will give the best sonic result. I know its tough to say but with transistors will be using lme49810 and with Mosfets lme49830.
From what I can remember.....there was a trend in SS Audio during the early 90's with using the Toshiba Lateral Mosfets ... The positive temp-co... I remember the SS OCM amps were considered generally "warm" and pleasing by some tube audiophiles back then... I think Dave Belles was involved with OCM... Not sure if Nelson Pass also used the Lateral Mosfets as well ???
There is no point in generalizing "sound" of different power devices technology. You can build amps with excellent technical data using BJT, ring emitter, HEXFET, lateral FET, whatsoever. An example howto tweak the Hitachi lateral FETs is found in my thread here "Just another lateral FET amp"
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They all have specific, unavoidable flavours. You think you can build amps with Toshiba 5200/1943 or ON 3281/1302 that will sound the same?
The perceived sound of an amp has to do with the design and transfer rather than the type of devices used. The intended required specs is what determines which type of devices are used. I have made crappy amps with "good" OPT, but also have made wonderful amps with OPT that are perceived as not suitable, such as cheap Darlingtons and HEX and planer stripe vertical fets.🙂
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The lack of secondary breakdown makes laterals very robust compared to other output devices - they are basically just dissipation limited.
All MOSFETs must be handled with full anti-static precautions until in-circuit. Good circuit designs incorporate protection zeners.
Check out the datasheet curves for a feel for linearity at any particular bias?
They are commonly used as replacements for obsolete hitachi devices I think, and there are plenty of amps and amp designs using those. The thermal stability and easy biasing are plus points, as is the higher frequency handling than BJTs. The cross-over linearity is poorer than well-biased BJTs, but better than poorly biased (or poorly temperature compensated) BJTs. The higher frequency handling can be used to add more negative feedback at HF to increase linearity.
Basically swings and roundabouts.
The simplicity of not needing fiddly temperature-compensated biasing arrangements definitely works in favour of laterals - fewer things to get wrong, fewer components needed. But the efficiency is less (more voltage overhead needed).
For class A the lack of secondary breakdown is a huge bonus I think.
Yes, and the trend with the Hitachi's was in the early 1980ies...
Best regards!
Soundcraftsmen used a lot of laterals in their amps.For the price they are some of the best sounding amps out there.Just look at how many are not for sale.Earlier models used Toshibas and later ones used Exicons.Class AB,biased around 200ma I think.I personally have a F7 clone that uses Alfet laterals,class A biased at close to 1 amp.I would put it up against any 20 watt amp out there.
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Oh and the Exicons are available in non-TO3 packages too which is a plus point over the original Hitachi devices. The TO247 single die versions are the cheapest variety too, although the TO264 double-die may be more convenient sometimes and are the same price per-die (so cheaper overall due to less mounting hardware).
I agree with Mark, the TO-264 dual die Exicon are nicer devices to work with vs TO-3 packaged parts. I have been using them for testing out the DH-220C design and also used them in a LME49830 design (OPC wire amp) from a few years back.
They are the most expensive OPS one can use so you have to figure out are they worth it. Since you bias them hot, you do need a bigger HS on average, so that can add extra cost to the design.
In the DH-220C design, I found the bias stability to be rock solid, if that matters or not, I am not sure. You are not going to get a bjt design to slew as fast, another does it matter, if rise/fall time is 600ns or 2us?
I loaded up OPC worksheet about latfet loading and supply V.
Static damage, use proper static handling procedures and you are okay. Assure your design uses clamps to prevent over voltage to G-S
There is to my knowledge one mfg left exicon, so for them to be still offering them someone must be using them in big enough volumes to justify current production. imo just like Linear system jfets, niche markets.
They are the most expensive OPS one can use so you have to figure out are they worth it. Since you bias them hot, you do need a bigger HS on average, so that can add extra cost to the design.
In the DH-220C design, I found the bias stability to be rock solid, if that matters or not, I am not sure. You are not going to get a bjt design to slew as fast, another does it matter, if rise/fall time is 600ns or 2us?
I loaded up OPC worksheet about latfet loading and supply V.
Static damage, use proper static handling procedures and you are okay. Assure your design uses clamps to prevent over voltage to G-S
There is to my knowledge one mfg left exicon, so for them to be still offering them someone must be using them in big enough volumes to justify current production. imo just like Linear system jfets, niche markets.
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