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Hoffman Amps Forum image Author Topic: Frequency Response Variations with Bias Cap Size  (Read 2127 times)

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Offline clyde

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Frequency Response Variations with Bias Cap Size
« on: January 20, 2024, 04:46:45 pm »
I've read that bias cap size on fixed bias circuits affects frequency response, ie larger uf = lower frequency response.  This was new to me and can anyone confirm the process by which this occurs?

Offline sluckey

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Re: Frequency Response Variations with Bias Cap Size
« Reply #1 on: January 20, 2024, 04:59:15 pm »
I've read green eggs and ham at least 500 times. Still don't believe it!    :icon_biggrin:
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline PRR

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Re: Frequency Response Variations with Bias Cap Size
« Reply #2 on: January 20, 2024, 05:06:32 pm »
Push pull or single-ended?

Competent designer or an idiot?

Offline clyde

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Re: Frequency Response Variations with Bias Cap Size
« Reply #3 on: January 20, 2024, 08:06:40 pm »
On another board, new poster. 

Offline WimWalther

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Re: Frequency Response Variations with Bias Cap Size
« Reply #4 on: January 20, 2024, 08:51:32 pm »
On another board, new poster.

If you consider the fact that a typical bias supply is isolated from the grids of the power tubes (and the driver circuit..) by 220-330K per tube, any effects related to bias supply capacity / impedance are kind of out the door.

ETA: This claim also has implications for bias regulators** which can be modeled as true voltage sources or huge caps.

(** which no one should use anyway, unless B+ is fully reg'd..)
« Last Edit: January 20, 2024, 08:57:53 pm by WimWalther »

 


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