Re: Access-312 Build Thread
« Reply #580 on: July 12, 2019, 07:32:22 PM »
OK

I did the measurements and the F2UEE push button switch is exactly 17.5mm apart from center of one switch to the next.

I bought the hardware chassis mounts for 17.5mm and it fits perfectly.


Re: Access-312 Build Thread New
« Reply #581 on: July 12, 2019, 07:54:29 PM »
I am also wondering about the details regarding the input pad, because I would like to mod my input pad to be -10dB in attenuation.

In the Access 312 circuit, is the pad an H-Pad, a T-Pad, or a U-Pad?

I'd like to change the resistors to produce a -10dB pad.  I think right now the pad is about -19dB with resistors R8 = 120r, R9 = 470r, and R10 = 470r

The input Z of my input transformer is typically 1500 ohms.  And I think its typical for a mic output impedance to be 150 ohms, right?
So I am not sure a -10dB pad is possible with my given impedances?

I used a T-Pad / H-Pad calculator at http://www.nu9n.com/tpad-calculator.html
The calculator could not compute a -10dB pad with these impedances...
and the only way I got close to the current -20dB pad was by making both input and output impedances both 600 ohms...
The results from the T-Pad were R1 = 491, R3 = 491, and R2 = 121 (bridge power load resistance)

Just trying to figure this out. If any one knows please offer your understanding. Thank you


« Last Edit: July 13, 2019, 07:05:04 AM by talkieparade »

Whoops

Re: Access-312 Build Thread
« Reply #582 on: July 12, 2019, 11:19:02 PM »
I am also wondering about the details regarding the input pad, because I would like to mod my input pad to be -10dB in attenuation.

In the Access 312 circuit, is the pad an H-Pad, a T-Pad, or a U-Pad?

Read this page, the answer is there:

http://www.uneeda-audio.com/pads/


 

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