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 Post subject: Rickenbacker cap .0047mF - What is the cut off frequency?
 Post Posted: Sat Oct 22, 2011 1:38 am 
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Joined: Fri Oct 21, 2011 12:43 pm
Posts: 27
Hi!

I'd like to try the vintage tone circuit with the .0047mF cap serial with the
bridge vol-pot. This is for guitar, i read forums mostly of bass.
I've done some research. It's a hipass filter.

So - What is the cut off frequency?
http://hyperphysics.phy-astr.gsu.edu/hb ... ilcap.html

If the cap is the same (.0047mF micro), it depends of the R, calculations give
R=250k > 68 Hz
R=330k > 102,5Hz
R=500k > 135 Hz

I read somewhere that Lo Mid would be cut out, so is this right?
Has someone measured this? If so then please tell R of the Vol.pot.

I heard that this vintage tone circuit would cut out Lo mids (250-500Hz?),
but it seems that only bass is cut out.

Are my calculations right here or am I forgetting something?

Has anyone measured the cut off frequency?

Thanks for any input!


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Sat Oct 22, 2011 7:58 am 
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Joined: Sun Mar 21, 2010 10:25 am
Posts: 16
Location: Left Coast, USA
laban1 wrote:
Hi!

If the cap is the same (.0047mF micro), it depends of the R, calculations give
R=250k > 68 Hz
R=330k > 102,5Hz
R=500k > 135 Hz

Are my calculations right here or am I forgetting something?


I think you mixed up 250K and 500K - my calculations show the frequencies at those resistances were swapped in your table.

Keep in mind this is only an approximation, and only really applies when the volume knob is up all the way, and the pickups are isolated by using the Ric-o-sound output. Turning down the volume knob lowers the resistance to ground, thus raising the corner frequency. Taking output from the mono jack always connects both volume pots in parallel, even if only the bridge pickup is selected.

If both pickups are on, the situation becomes much more complicated.

I think the .0047 cap was only used on the 4001 bass family. I'm not aware of it ever having been used on guitar.


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Sat Oct 22, 2011 10:16 am 
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Joined: Sun Jan 08, 2006 2:00 pm
Posts: 130
Location: Homestead Florida
try iiipopes vintage tone mod. post
lots of info here

GTB


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Sat Oct 22, 2011 9:28 pm 
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Joined: Fri Oct 21, 2011 12:43 pm
Posts: 27
Hi, yes I swapped the 250k and 500k, thanks!

"Taking output from the mono jack always connects both volume pots in parallel, even if only the bridge pickup is selected."

Have no rickosound, Looking at wiring for mono http://www.rickenbacker.com/pdfs/19511.pdf

Yes, this is because of the blender, right?
So if I have 330k pots (as an example) leaving both on max output,
then I would have half the resistance, 165k > 205Hz

But wait, it looks as the blender 500k is on (and fixed value) even if I use bridge only, then 500k // 330k neck (max) > 200k (close)

So then its 200k//330k (bridge) = 124k > 273 Hz
This would be the minimum cut of frequency and turning any pot would cut out even more.

Is this right? Any comments would be appreciated!


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Sun Oct 23, 2011 7:59 am 
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Joined: Mon Mar 05, 2007 12:33 am
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Location: Denver
I believe it's a little above 100 Hz based on real-time spectra I have watched after toggling the cap back and forth.


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Sun Oct 23, 2011 10:12 am 
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Joined: Fri Oct 21, 2011 12:43 pm
Posts: 27
Hi Cassius!
That was intresting, was that FFT-analysis?
Which guitar/bass was it?
Did you use the ric-o-sound mono? Was this Bridge PU only on the swich?
Do you know what pots it was?


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Thu Oct 27, 2011 10:30 pm 
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Joined: Fri Oct 21, 2011 12:43 pm
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Anyone,... any input?


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Fri Oct 28, 2011 2:22 pm 
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Joined: Mon Mar 05, 2007 12:33 am
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Location: Denver
laban1 wrote:
Hi Cassius!
That was intresting, was that FFT-analysis?
Which guitar/bass was it?
Did you use the ric-o-sound mono? Was this Bridge PU only on the swich?
Do you know what pots it was?


Modern 4003. Bridge pickup soloed, mono. 330k pots (more like 300).


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Sat Oct 29, 2011 11:58 am 
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Joined: Fri Dec 25, 2009 9:29 pm
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Location: Appleton
I just ran a quick RTA on mine- 200hz and above seem unaffected, but the graph begins to noticeably change between 100 and 200 per the cap position. At the 100hz mark and below, its an obvious cut.


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 Post subject: Re: Rickenbacker cap .0047mF - What is the cut off frequency
 Post Posted: Sun Oct 30, 2011 5:30 am 
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With the fundamental of the low E string being 80 Hz, this makes sense. Also, remember it's not just the cutoff frequency. All frequencies above the cutoff are shifted 90 degrees, which is a major element contributing to the jangle.


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