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Old 10th March 2011, 04:06 PM   #1531
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Totally agree that R36 is 22 ohm. If it had been 0.22 ohm it would have been marked R22
or 0.22R. Thank you for this observation.

In simulation it will now handle 700 mW instead of 8W at full peak power into 8 ohms.
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Old 10th March 2011, 04:45 PM   #1532
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I am totally agree with NagysAudio
All the circuit he provide is correct as in real Goldmund 9.2
See attached

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File Type: jpg IMG_0002.jpg (378.7 KB, 1193 views)
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Old 10th March 2011, 04:46 PM   #1533
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hey the purpose of the output inductor resistor is to damp any ringing the coil may create at high frequencies. normal rule of thumb to make value at least twice the minimum value of the intended load. also make sure you use a device that does not exhibit any inductive of its own. I only use good old fashioned carbon 3-5watt and use it as a former for the inductor. wirewound or metal film is not really suitable for this. in fact the best results for high speed MOSFET dvices such as this work best with an all carbon resistor set. on numerous occasions I have come acroos people/DIYer's that change resistors in old equipment such as valve amps or tuners then wonder why they no longer function well or in the case of tuners at all. been watching this project thread with interest. understand as told to me prior post dunno the number its about "the attention to details" not too sure but think some or most of the resistors used on these amps are metal film. whereas I would not do this.
I have been doing reseach into Mosfet devices for audio for over 20 years. had a client who borrowed a design prototype from me years ago to compare to a musical fidelity and a Krell despite my asking him to return it some weeks later he only wanted to give me cash!!! not the unit so think building high quality audio is the norm for me. can someone clarify the used resistor set for this out of curiousity
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Old 10th March 2011, 05:33 PM   #1534
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I would be nice to know the bandwidth/resonant freq. of that L/R combo to see what it should be....

According to this... CalcTool: RLC or LC circuit calculator

the .22R/2uH has a limited bandwidth (17Khz). I use 10R/1.5-2UH in my amps (better BW - 800k) since the only purpose is to attenuate RF at the OP. (absorbed by speaker wire , etc)

So , by all reasoning ... .22R/2uH IS WRONG.

EDIT: unless ,in the case of the goldmund , the limited BW is there to accommodate RF created from WITHIN the amp.

OS
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Last edited by ostripper; 10th March 2011 at 05:38 PM.
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Old 10th March 2011, 06:22 PM   #1535
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Thank you arthur for your post. It answers a lot of questions and raises some more...

ostripper,
I have found this information about amplifier stability:
Elliott Sound Products - Audio Power Amplifier Design Guidelines
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Old 10th March 2011, 06:59 PM   #1536
Krisfr is offline Krisfr  United States
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Speaking of CLR calculations, does anyone remember a Tektronix CIRCULAR Slide Rule like marked calculator for RCL circuits, does anyone have one that a photo pdf can be taken? It was a super good tool in its day... I loved it, I had 2 but they got lost in the life somewhere...
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Old 10th March 2011, 09:59 PM   #1537
loek is offline loek  Netherlands
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Default CRL

Maybe this can help?
The RF-Wallpaper / Die HF-Tapete
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Old 11th March 2011, 10:49 AM   #1538
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Quote:
Originally Posted by arthur View Post
All the circuit he provide is correct as in real Goldmund 9.2
Shame Nagy isn't around to see the power devices type/number used in the 1/2 priced, and 1/3d lower power model.

Didn't that GM brochure state that the 250W monaural used the same circuitry as the 9.2 ?
=> R95/R96 = 2k2 ( or 1k8/100V)
http://ouir.ch/generated/datenblaett..._Mimesis_9.pdf
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Old 11th March 2011, 12:24 PM   #1539
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Quote:
Originally Posted by Krisfr View Post
Speaking of CLR calculations, does anyone remember a Tektronix CIRCULAR Slide Rule like marked calculator for RCL circuits, does anyone have one that a photo pdf can be taken? It was a super good tool in its day... I loved it, I had 2 but they got lost in the life somewhere...
It's in here, somewhere ....

Slide Rules for sale on-line! Sphere's Circular Slide Rule Page
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Old 11th March 2011, 12:53 PM   #1540
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Cliff,

Kris just asked for images, to make one himself with a couple of CD's.

Like this :
http://classictek.org/images/stories...puter_1961.pdf
http://sliderulemuseum.com/HSRC/58111.jpg
http://cgi.ebay.com/VINTAGE-TEKTRONI...-/190509192793

(oh dear, i just enlisted in the old fart brigade)
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Last edited by jacco vermeulen; 11th March 2011 at 01:03 PM.
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