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Old 28th June 2012, 06:21 PM   #71
Bensen is online now Bensen  Belgium
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Quote:
Originally Posted by homemodder View Post
Here is another interesting outputstage. Any comments on the connection of those cascodes ?? In spice its hardly stable but the schematic shown is a real commercial offering.
Can you tell me from which commercial amp this is.
I simmed a few days back something 90% equal to that.

Regarding the cascode connection: they are looking pretty normal to me?

Greetz
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Old 28th June 2012, 07:34 PM   #72
vsat88 is offline vsat88  United States
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All I can say is...Awesome !
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Old 28th June 2012, 10:37 PM   #73
Bonsai is offline Bonsai  Taiwan
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Quote:
Originally Posted by Dave Zan View Post
Bob also recommended diode bias with ThermalTrak diodes as the driver emitter load. It looks nice to me, the dynamic resistance can be very low.
Have you looked at this?

Best wishes
David

BTW For a while I have meant to say thanks for the Middlebrook link on your website. Very "low entropy" information.
Dave, no - I have not looked at it seriously - something for a future project!
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Old 29th June 2012, 01:25 PM   #74
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Quote:
Originally Posted by Bensen View Post
Can you tell me from which commercial amp this is.
I simmed a few days back something 90% equal to that.

Regarding the cascode connection: they are looking pretty normal to me?

Greetz
That is from Inter, I dont know much about them, the scheme is used by accuphase as well since 1990s so there must be advantages except I cant get it stable....yet that is.

The cascodes would be conventional except here the base of the cascode is connected to the sources of the mosfets. Conventional cascode the bases of the cascodes would be connected to each other with no connection to the sources of the mosfets. As it is it looks more like hawksford type cascode connection and probably why it has stability issues.
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Old 1st July 2012, 07:45 AM   #75
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Hello Andrew,

Thank you very much for taking the time to write up your new amplifier so thoroughly! There's lots of useful ideas in there.

I was just wondering why you chose to use an isolated solid-state relay with optocoupled gate drive rather than the non-isolated design detailed in your separate document on SSLRs? The non-isolated one is cheaper, could I think be optimised for lower power consumption in the gate drive circuit, and is less expensive. What are the advantages of the isolated one?

Also, I have some feedback regarding presentation/grammar/punctuation of your document. Do you mind if I post it here? (Some of the observations and tips may be useful to anyone working on technical documents).

Thanks again,

Harry.
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Old 1st July 2012, 11:08 AM   #76
Bonsai is offline Bonsai  Taiwan
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Hello Harry, thanks for your comments.

The control board used in the e-Amp was designed (and the 1st iteration of the PCB's done) before I cooked up the non-isolated version. I am currently working on two new amplifiers that use the non-isolated version.

For the feedback part, please email me at andrewc.russell(at)gmail.com - I welcome your comments.
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Old 1st July 2012, 02:25 PM   #77
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Quote:
Originally Posted by HarryDymond View Post
Also, I have some feedback regarding presentation/grammar/punctuation of your document. Do you mind if I post it here? (Some of the observations and tips may be useful to anyone working on technical documents).
I hope to do an article sometime and would appreciate the tips
Quote:
Originally Posted by Bonsai View Post
For the feedback part, please email me at andrewc.russell(at)gmail.com - I welcome your comments.
Understandable to want to receive feedback privately but can you post it here after you have read it? Maybe remove any bits you feel sensitive about?
Or can Harry post a redacted (I believe that's the current euphemism) version?

Best wishes
David
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Old 1st July 2012, 03:01 PM   #78
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Originally Posted by Dave Zan View Post
I hope to do an article sometime and would appreciate the tips

Understandable to want to receive feedback privately but can you post it here after you have read it? Maybe remove any bits you feel sensitive about?
Or can Harry post a redacted (I believe that's the current euphemism) version?

Best wishes
David
As Andrew requested the feedback via email, I am currently authoring very detailed feedback that lists all the "errors" I found and as such this is not the right place to post it. I have started a thread for those that are interested in my general comments concerning punctuation etc. in technical documents. Please note these are general comments and not necessarily prompted by Andrew's document.

David (and anyone else), feel free to make comments there so it doesn't look like I'm talking to myself!
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Old 2nd July 2012, 01:44 AM   #79
Bonsai is offline Bonsai  Taiwan
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Harry, here are the output devices I am using

ON Semiconductor NJW1302: Audio Bipolar Power Transistors, 200 W

TO-3P package - I saw some notes elswhere on the forum that ON never seemed to make a splash about these when they were released.
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Old 2nd July 2012, 05:41 AM   #80
Bonsai is offline Bonsai  Taiwan
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Indeed, the 1381 is a figment of my imagination - thanks for catching that one!

here are the correct device numbers:-

NJW3281G
NJW1302G
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