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Rank: Member
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Joined: 1/1/2010
Posts: 8
Location: Snowy WIsconsin
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Got my kit today and have a few questions re assembly:
- no C1-C4 in the kit (although they are in the BOM). Are these optional?
- I assume the jumpers are to be used if a single power supply is used. Correct?
- Any guide (picture?) on how to use the headers to connect the IVY and Buffalo?
Thanks
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Rank: Administration
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Joined: 10/24/2006
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Location: Nashville, TN
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Ah, I see Brian must not have had time to get the manual up on the site.
You should have C1-4. They are not strictly required, but you will not have any filtering. Brian will see this I am sure and get you straightened out.
I will see if Brian can get the manual up.
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Rank: Administration
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Hopefully these images can help.
Russ White attached the following image(s):
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Rank: Member
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Location: Snowy WIsconsin
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Thanks Russ. The pictures are very helpful. I have it up and running now and am very impressed with the sound. What is the purpose of the filtering provided by C1-C4?
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Rank: Administration
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I am glad you have it running. Good Work.
It forms a low pass filter to keep out out of band noise.
10nf to 15nf there is fine.
Cheers!
Russ
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Hi Russ. Do you find that there is any audible difference between 10 and 15 nF? If my calculations are correct, 15nF puts the rolloff frequency at 27.2 kHz while 10nF puts it at 40.8 kHz. Either way well above the audible threshold, but just wondering if you can tell the difference.
Thanks
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Rank: Administration
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Yes, with an oscilloscope. :)
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The funny thing is that typically the older, more knowledgeable people are the ones that can "hear" these differences. The other day I was testing the filters in the OPUS and I was playing, I think a 16K tone at full blast, because I could not hear it (or barely hear it, I don't quite remember). My daughter who was in another room was shouting at me: "can you shut that down dad, it is very annoying!!!" :-)
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Rank: Administration
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The filter has a shallow slope. Only 3db. So your not going to hear much difference either way. Feel free to experiment as there is no harm running it even with say 1nf filter caps. :)
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Rank: Administration
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Also I should clear something up. The corner frequency is not 27.2khz with 15nf, its actually about 54.4395Khz :)
I will leave it as a learning exercise for the reader to figure out why, but I can assure you it is true. :)
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Rank: Member
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Location: Oslo, Norway
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Hi!
I guess the reason the -3dB corner frequency is twice the easily immediately assumed is that the node at the filtering point sees both the 390 ohms resistors in parallell (as a Thevenin equivalent). Then the calculation for the corner frequency gets: fc = 1 / (2*pi*R*C) = 1 / (2*pi*195ohm*15nF) = 54411.95 Hz
:)
audiophile
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