You hadn't edited the post to include the ASC when I wrote, so thanks.
I will have a look today.
Best wishes
David
Still two errata's -
1-20Khz right at overload , class H dips into shutoff (class C).
2 -10K -20Khz deep into overload , class H also dips into shutoff.
20hz to 15K , always 25ma idle in class H.
Normal music would be like my post 100 picture ... 100-500hz
carrying a 10K waveform ( bass or voice with cymbals or brushes).
sub 10ppm with idle under these conditions.
So , it is essentially non-switching under all normal conditions , even
10K carrier with a 200khz waveform ... not normal conditions.
If it dips into shutoff during clipping , who cares ? Many percent THD
anyways ?? It does stay very stable on overload.
OS
1-20Khz right at overload , class H dips into shutoff (class C).
2 -10K -20Khz deep into overload , class H also dips into shutoff.
20hz to 15K , always 25ma idle in class H.
Normal music would be like my post 100 picture ... 100-500hz
carrying a 10K waveform ( bass or voice with cymbals or brushes).
sub 10ppm with idle under these conditions.
So , it is essentially non-switching under all normal conditions , even
10K carrier with a 200khz waveform ... not normal conditions.
If it dips into shutoff during clipping , who cares ? Many percent THD
anyways ?? It does stay very stable on overload.
OS
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Three possible reasons *imho*:
- Replace the predrivers' emitter resistors by a single one (680R) that isn't referred to the output bus.
- Replace the drivers' emitter resistors also by a single one (220R).
- Two pairs of 2SA1943/2SC5200 might not be sufficient at +/- 65 V rails.
Best regards!
Ever so true! Minimum is about 6 pairs for 4R operation safety at those rail voltages.
Let the "magic smoke" out of 5200/1943 pairs @ 60V !
But , 3 pair MT-200's ran <4R subwoofer with no problems.
The AX amp would be better served by 45-50V rails.
Amps I test on my 45V supply tend to run real cool and never
fail. 2sc5200 DC / 100mS SOA is little more than an amp at 65V.
Nice healthy 10/6A at the 20-30V low rail of the class H.
The class H crest with 8 devices is 40/80V rails and is rated at 400/700w (not PMPO).
I don't believe in OEM power ratings , even class H ones.
Then there is PMPO .... what a scam !!
OS
But , 3 pair MT-200's ran <4R subwoofer with no problems.
The AX amp would be better served by 45-50V rails.
Amps I test on my 45V supply tend to run real cool and never
fail. 2sc5200 DC / 100mS SOA is little more than an amp at 65V.
Nice healthy 10/6A at the 20-30V low rail of the class H.
The class H crest with 8 devices is 40/80V rails and is rated at 400/700w (not PMPO).
I don't believe in OEM power ratings , even class H ones.
Then there is PMPO .... what a scam !!
OS
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Hi Pete
Have you thought about what to replace the 4793-1837 pair with? These are out of production and not second-sourced, and trust-worthy suppliers like Mouser and Digikey do not have them. Some of what is offered by Asian suppliers are thought to be fakes by buyers who test them.
Toshiba's own replacements for the 2SC4793 and 2SA1837 are TTC004 and TTA004, respectively. These are only good to 160V and their gain curves are not as flat as the originals. They are also in a fully-encapsulated TO-126N package, so smaller and lower dissipation.
Have you thought about what to replace the 4793-1837 pair with? These are out of production and not second-sourced, and trust-worthy suppliers like Mouser and Digikey do not have them. Some of what is offered by Asian suppliers are thought to be fakes by buyers who test them.
Toshiba's own replacements for the 2SC4793 and 2SA1837 are TTC004 and TTA004, respectively. These are only good to 160V and their gain curves are not as flat as the originals. They are also in a fully-encapsulated TO-126N package, so smaller and lower dissipation.
I have the models for all 3 groups , I prefer the sankens.
Any will work with my OPS layout.
The important thing is the 30V SOA for class H is 6A+ on all of them.
My preference for the Sanken's is the ring emitter process , 60MHZ ft
, and higher Hfe.
I can't find those 20A semilab BJT's any more , so class H is the only
way to coax more SOA out of less "premium" devices.
I said on another thread , a full Sanken output stage could reproduce
the full 380V/uS slew out of one of the faster CFA's.
ON/toshiba's are a bit "slower", but still sufficient for normal 50-200V
slew in "normal" amps.
I do not think there will be much difference in the "greenamp".
OS
Not really. Toshiba recommends TTC004B/TTA004B instead of 2SC3421/2SA1358, which has almost same data.
2SC4793/2SA1837 has no replacement, unfortunately, but Saken 2SC4883/2SA1859 can be quite good. Digikey has them in stock...
Sajti
2sc4483/2sa1859 are $1.62 each. My only drivers.
To avoid "obsolete" , ZTX957/857 SOT223 for VAS (and EF3 predrivers) $.98c.
And any of the Sanken outputs.
I'm not scared of SMD , might make layout easier.
Current sense SMD resistors - large package 12mm long 2 X .3R/2W
https://www.mouser.com/datasheet/2/427/wsrhigh-239701.pdf
should give me .125R for my output tranny Re.
Solder these right between TO-3P trace and output rail trace.
Just TO-126 Vbe , TO-3P output , TO-220 drivers , and the
bigger electrolytics will be through-hole.
The IPS will be all ZTX SOT223 (VAS) or 363 mini sot,
P/N matched 300MHZ Ft BC847PNQ SOT-363.
https://www.mouser.com/datasheet/2/115/BC847PNQ-1147921.pdf
One tiny little fast diamond for the CFA. Thermal glue a copper plate
on top .... thermally equalized CFA - CCS/diamond/VAS.
Led's are tiny , too - the Cree 100k/hr , low intensity.
https://www.mouser.com/datasheet/2/90/CLM3CRKWAKW1156-274590.pdf
2.1Vf ,, a whole $.11c each.
That's why I liked Dadod's little IPS board , I just want a flat small SMD one.
Just one wooden chopstick to hold the bits down , tack one side / repeat / done.
I did VZaudio 's protection board , the SMD was easier than the leaded junk.
NO clipping , or looking to the other side of the PCB.
OS
To avoid "obsolete" , ZTX957/857 SOT223 for VAS (and EF3 predrivers) $.98c.
And any of the Sanken outputs.
I'm not scared of SMD , might make layout easier.
Current sense SMD resistors - large package 12mm long 2 X .3R/2W
https://www.mouser.com/datasheet/2/427/wsrhigh-239701.pdf
should give me .125R for my output tranny Re.
Solder these right between TO-3P trace and output rail trace.
Just TO-126 Vbe , TO-3P output , TO-220 drivers , and the
bigger electrolytics will be through-hole.
The IPS will be all ZTX SOT223 (VAS) or 363 mini sot,
P/N matched 300MHZ Ft BC847PNQ SOT-363.
https://www.mouser.com/datasheet/2/115/BC847PNQ-1147921.pdf
One tiny little fast diamond for the CFA. Thermal glue a copper plate
on top .... thermally equalized CFA - CCS/diamond/VAS.
Led's are tiny , too - the Cree 100k/hr , low intensity.
https://www.mouser.com/datasheet/2/90/CLM3CRKWAKW1156-274590.pdf
2.1Vf ,, a whole $.11c each.
That's why I liked Dadod's little IPS board , I just want a flat small SMD one.
Just one wooden chopstick to hold the bits down , tack one side / repeat / done.
I did VZaudio 's protection board , the SMD was easier than the leaded junk.
NO clipping , or looking to the other side of the PCB.
OS
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Yes , second CFA stage instead of a992/c1845's.
The whole IPS will be 60mm X 60mm.
even solid caps for the zener bypass.
Bye - bye 20'th century for the IPS.
We can still have our through-hole "fun" on the output stage.
With an introduction to the bigger SMD along the way.
OS
OS, I'm excited to see you really up and running. As usual most of your design decisions are way over my head but I'm still a good mechanic.
I've got 20 pair of sanken 1295/3264 outputs and a couple of big linear power supplies. Would be fun to be able to replace the pair of crown ce2000 amps I use for parties.....
I've got 20 pair of sanken 1295/3264 outputs and a couple of big linear power supplies. Would be fun to be able to replace the pair of crown ce2000 amps I use for parties.....
Hi , EvanC -
(Below) the CE2000 is not even a class G/H.
Just a triple stage Quasi-symmetrical push–pull at 85V rails.
Just the 5 pair slewmaster output stage.with class G switching at 40V and 120V rails - would be a 2KW amp !! ,and out - power both crowns.
The "greenamp" with 12 devices total would also dance on the crowns.
Class G/H is a definite power multiplier.
PS - crowns are still nice - very heavy duty MJL21194 outputs.
I will make a 8 device "greenamp" = 400W 8R / 700W 4R. Way smaller
for the same power / weight / heatsink .
OS
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I really hope you do it with Laterals PLEASE
PLEASE with ExiconsExicon Lateral MOSFETS - Why use Exicon?
I really hope you do it with Laterals PLEASE
Exicon Lateral MOSFETS - Why use Exicon?
I promised that at the beginning.
My first adventure will be to be "inspired" by Dadod's latfet amp
OPS , and graft it on to my CFA.
The latfet's gate capacitances , any Vbe considerations , and protections ...
I must learn.
Dadod gave me the Exicon models - so why not! That's why I asked for them.
Should be easy to port the "greendrive" trackers over to them.
Or , just a little "peanut" amp , easy enough for beginners.
OS
LatFETs have some nice aspects but are likely headed for obsolescence.
IXYS have some VFETs with serious power capability.
I did VDMOS models with all the latest refinements for Toni.
These have been tested and work well and have been posted in DIYaudio if you're interested.
I have started to sim your amp, it looks like you have put in a lot of work, some nice ideas.
But I think I can "stand on your shoulders" and raise the bar a bit more.
I still look forward to your discussion of Class H.
Best wishes
David
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