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Old 20th March 2012, 08:01 AM   #2131
hahfran is offline hahfran  Germany
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Default SSA all BJT and Thermal trak

The SSA employs a cascode which acts as CS. This CS can possibly not charge discharge the gate source capacitance of the MOS fast enough, moreover,
all paraistic capacitances of MOS depend highly non linear on gate source voltage and so on, and according to semiconductor physics, must be different for p channel MOS.
I would like the SSA all BJT and current driven throughout because power BJTs can have a perfectly linear ic/ib up to about 5 amps that is enough for 50 watts amp.
I will use one pair of thermal trak BJTs and thus the first design obstacle is how to control a Vbe multiplier with these on subtstate diodes thus that the operating point is independent of the junction temp of the power BJTs.
Remeber there are TWO diodes not four.
Ana ideas?
Thx
Hans Dieter
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Old 20th March 2012, 08:08 AM   #2132
sonnya is offline sonnya  Denmark
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Quote:
Originally Posted by pinnocchio View Post
I guess you've been sponsored by Aussie amplifiers...

Ripoff or not, it is the diy world. people want to learn and experience. And btw, Pass is supporting diy efforts.

However, true, the FetZilla is really good and I have built it along with many "ripoff" amplifiers that sound extremely good!

Good thing I'm in America!

Do
Just for the record: I do not have a relation to Anthony, nor have i bought his kits.

But you must admit that he put out more new deisgn per year than most other companies!?

I am fully aware that Nelson is supporting the DIY crowd with a lot designs.

And i can see that you have build the Differenitial poweramp from AMB laborities. He does also contribute with a lot of designs.

Aksa has his own design too.

But besides from that?

I was just tired of seeing all the same design over and over again that have been out there for 5 - 15 years. That was all it was about. And it was refreshing that there have been new designs from the scratch in this forum.
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Old 20th March 2012, 08:37 AM   #2133
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Quote:
Originally Posted by hahfran View Post
The SSA employs a cascode which acts as CS. This CS can possibly not charge discharge the gate source capacitance of the MOS fast enough, moreover,
all paraistic capacitances of MOS depend highly non linear on gate source voltage and so on, and according to semiconductor physics, must be different for p channel MOS.
Hi Hans

SSA BIGBT HP is very fast design it has -3 dB CLG margin around 3 MHz and slew rate more than 300 V/us and that info is for ready made amp in the box, if you know what that means.

In SSA BIGBT HP predriver/VAS stage has 10 mA bias and current response up to 100 mA with ease, so driving two IRF gate's is a peace of cake.

IRF's drivers are vertical MOS FET intended for fast switching applications and in BIGBT configuration they are perfectly suitable for audio purpose. This is probably the best output device to my opinion and it's really a shame that more of DIY-ers don't test and use them because they are inherently stable, very imune to self oscillations, easy to drive, has enourmous current capability (30 A) and has positive characteristics from both common emmiter/collector output configuration in one device ("balanced").
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Old 20th March 2012, 08:42 AM   #2134
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Quote:
Originally Posted by sonnya View Post
But besides from that?

I was just tired of seeing all the same design over and over again that have been out there for 5 - 15 years. That was all it was about. And it was refreshing that there have been new designs from the scratch in this forum.
I'm sorry but I think the SSA BIGBT HP is not really all the same design like they are circulating around there copying each other. Apologies in advance if I didn't fully understand your statement.

Last edited by Lazy Cat; 20th March 2012 at 08:44 AM.
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Old 20th March 2012, 08:46 AM   #2135
sonnya is offline sonnya  Denmark
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No problem.

I was not clear enough.

The SSA BIGBT HP IS NEW AND REFRESHING...
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Old 20th March 2012, 08:51 AM   #2136
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Originally Posted by sonnya View Post
I think it is time that we in europe starts constructing something new and innovative like this amp, The FETzilla.
OK thanks for clearance sonnya. Upper sentence could told me this but you know I am always a little bit too sceptic of what I do.

Regards, Andrej
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Old 20th March 2012, 08:59 AM   #2137
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Originally Posted by a.wayne View Post
Very nicely done LC, any concerns with transf so close..? if not the packaging is exquisite..


Congrats ...............
Thank you a.wayne

No difference to output noise or 50 Hz hum from "before" to "after" setup. There is simply nothing at the output no matter of the toroids position.
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Old 20th March 2012, 09:18 AM   #2138
hahfran is offline hahfran  Germany
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Originally Posted by Lazy Cat View Post
Hi Hans

SSA BIGBT HP is very fast design it has -3 dB CLG margin around 3 MHz and slew rate more than 300 V/us and that info is for ready made amp in the box, if you know what that means.
so this slew rate is obtained from an actual device driving what load?
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Old 20th March 2012, 09:31 AM   #2139
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Originally Posted by hahfran View Post
so this slew rate is obtained from an actual device driving what load?
Real load, 6 ohm speaker connected, 10/100 kHz square wave, positive edge slew measured.

Last edited by Lazy Cat; 20th March 2012 at 09:34 AM.
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Old 20th March 2012, 09:42 AM   #2140
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Hi LC,

Is the BIGBT schematic joined already usable. Your latest HP version is out of range for me? I am affraid that the thermaltack version (2x25vac rail) i worked on doeasn't present sufficient power to drive speaker i planed in my room.

Marc
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