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Old 2nd December 2013, 07:15 PM   #3871
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Hi!

I'm building this preamp and I have a question. The volume control is a linear taper 25K. Is it possible to use a stepped LOG attenuator?

Thanks!
Sjoerd
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Old 2nd December 2013, 07:31 PM   #3872
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Sure.
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Old 2nd December 2013, 08:31 PM   #3873
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What is the difference?
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Old 2nd December 2013, 08:41 PM   #3874
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The rate of change... here is a very good starting point:

tangentsoft.net/audio/atten.html
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Old 2nd December 2013, 08:43 PM   #3875
Marra is offline Marra  United Kingdom
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With a linear pot the volume goes loud with only a few degrees of turning.Not sure of the more technical description.
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Old 3rd December 2013, 01:08 PM   #3876
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Ah ok, thanks! I guess linear is what is in my Marantz PM-17(I use it as my preamp on my Hiraga)

It goes loud real fast! So stepped log is the better choice I guess. That's good because the Glasshouse attenuator is already finished :-)

Let the build begin!

Thanks again!

Sjoerd
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Old 3rd December 2013, 04:44 PM   #3877
AndrewT is offline AndrewT  Scotland
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I would be surprised that Marantz fit a linear track volume pot.

You often find a linear track pot on the input of PA Power Amplifiers where you know the sensitivity setting from the rotation of the adjuster knob.
10% of rotation requires 10 times more signal.
50% rotation requires 2 times more signal.
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Old 7th December 2013, 09:10 PM   #3878
AntonTR is offline AntonTR  Russian Federation
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Default Grounding for B1

Dear friends,
Sorry, if this question was already discussed but I still have not met the answer.
Hope someone will help me.
The B1 board from Mr. Nelson Pass has mounting holes which are connected with GND conductors on the board.
So, it seems, that it was assumed that board GND circuit to be connected to the chassis... At the same time in F5, the signal GNG is separated from EARTH via thermistor.
Please, kindly advice me which way should I follow here - to use insulated mounting pins and use thermistor as in F5 or to use chassis as a signal ground (doubtfull)?

Best regards, Anton
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Old 10th December 2013, 10:34 PM   #3879
mach1 is offline mach1  Australia
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Default Dispensing with R1and C1

If I were to implement an LT 1963A based regulator in the chassis to supply 18V would R1 and C1 become effectively redundant ?
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Old 14th December 2013, 10:22 AM   #3880
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Aaargh, I broke my attenuator end notch!!! I was trying to get the knob of #unhappy
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