Are C101 & 201 the output coupling capacitors?
If so then 10uF is not written in stone.
The treble roll off depends on the capacitor value and the load impedance.
The Receiver sets the load impedance. Typically these can be anywhere in the range 10k to 1M.
The treble roll-off can be predicted with the usual formula:
Fr = 1 / {2PiRC}
for a 47k input impedance (at the power amplifier input) the roll off would be at 1/{2Pi*47000*10/1000000} = 1/{Pi*0.94} ~ 0.3Hz
You choose this roll-off frequency to suit what LF you want to pass from the Buffer+Source to the Receiver.
Adjust the capacitor value to suit the required frequency and your worst case Receiver input impedance.
For 10k use 4u7F to 22uF
for 100k use 470nF to 2u2F
for 1M use 47nF to 220nF
Notice that you would ONLY require a 10uF coupling capacitor for low input impedances. Going bigger than necessary achieves no benefit.
If so then 10uF is not written in stone.
The treble roll off depends on the capacitor value and the load impedance.
The Receiver sets the load impedance. Typically these can be anywhere in the range 10k to 1M.
The treble roll-off can be predicted with the usual formula:
Fr = 1 / {2PiRC}
for a 47k input impedance (at the power amplifier input) the roll off would be at 1/{2Pi*47000*10/1000000} = 1/{Pi*0.94} ~ 0.3Hz
You choose this roll-off frequency to suit what LF you want to pass from the Buffer+Source to the Receiver.
Adjust the capacitor value to suit the required frequency and your worst case Receiver input impedance.
For 10k use 4u7F to 22uF
for 100k use 470nF to 2u2F
for 1M use 47nF to 220nF
Notice that you would ONLY require a 10uF coupling capacitor for low input impedances. Going bigger than necessary achieves no benefit.
Thanks AndrewT, yes, it is the output coupling capacitor. The worse case input impedance that I will have in my system is 15k, so I figure 10uF is still an acceptable value. However, I now have a problem with the physical size of the capacitor that I ordered previously, which is the Ampohm (it is gigantic, so wont fit in the chasis that I have ordered), and am thinking of replacing it with the Vishay which is much smaller in size. The capacitance value of the replacement is the same, and it is also a film type capacitor, just not of the "exotic audio" type. I am wondering would there be audible difference?
And using the formula to make an alternative calculation, a cap value of 4u7F would still be acceptable, therefore I can order an audio grade capacitor at 4u7F which should be smaller in size and might just fit the chassis.
Which approach is better? Non-audio grade capacitor at 10uF or audio grade capacitor at 4.7uF?
And using the formula to make an alternative calculation, a cap value of 4u7F would still be acceptable, therefore I can order an audio grade capacitor at 4u7F which should be smaller in size and might just fit the chassis.
Which approach is better? Non-audio grade capacitor at 10uF or audio grade capacitor at 4.7uF?
Do you realise that if you have the DC blocking capacitor fitted to EVERY power amplifier you have, then you DON'T need a second DC blocking capacitor in the source?
Locating the DC blocking capacitor in the power amp allows you to select the correct capacitor for that input impedance and avoids any what if, or worst case calculations.
Locating the DC blocking capacitor in the power amp allows you to select the correct capacitor for that input impedance and avoids any what if, or worst case calculations.
Actually I have not thought about the power amp having the blocking capacitor. It definitely safes the hassle if all the power amps have it. Well, since I have already purchased it, I will just use it. In fact, I got both the cheap and the giant one, both 10uF. I will probably go with the cheap and small one in the first round of assembly, once the buffer is up and running, replace it with the giant one to see if it sounds better. The catch being if I like the sound of the giant one, I cant close the lid of the chasis, so it will probably be a "painful" experience having to replace the cheap one back just so that I can close the lid.
every manufacturer with any sense towards warranty claims will fit a DC block at their output and/or at their inputs.
In many cases we end up with a DC blocked Source driving a DC blocked Receiver.
As I have said many time before on this Forum>
fit dual outputs and dual inputs. One of which bypasses the standard DC blocking capacitor.
Then you have the choice of bypassing the lesser performing DC blocker.
eg.
A source with a 100nF DC blocker suitable for driving power amp receivers with a Zin >=100kHz
And a Power amp with Zin=47K fitted with a 1uF DC blocker.
Fitted as standard you end up with an effective capacitance feeding the 47k of 0.1uF*1uF/(0.1uF+1uF) = ~91nF
F-3dB = 1/2/Pi/47k/91nF ~ 37.6Hz
Bypass the 100nF and you get F-3dB ~3.4Hz
You get your bass back.
In addition some will use crap capacitors (to save a penny). Bypassing gives you the choice to avoid the obvious crap.
In many cases we end up with a DC blocked Source driving a DC blocked Receiver.
As I have said many time before on this Forum>
fit dual outputs and dual inputs. One of which bypasses the standard DC blocking capacitor.
Then you have the choice of bypassing the lesser performing DC blocker.
eg.
A source with a 100nF DC blocker suitable for driving power amp receivers with a Zin >=100kHz
And a Power amp with Zin=47K fitted with a 1uF DC blocker.
Fitted as standard you end up with an effective capacitance feeding the 47k of 0.1uF*1uF/(0.1uF+1uF) = ~91nF
F-3dB = 1/2/Pi/47k/91nF ~ 37.6Hz
Bypass the 100nF and you get F-3dB ~3.4Hz
You get your bass back.
In addition some will use crap capacitors (to save a penny). Bypassing gives you the choice to avoid the obvious crap.
Thanks AndrewT for this insightful information. I will definitely want to see if having a bypass switch is possible on the buffer side. However, unfortunately with other commercial products, it might not be possible to have it. One example being my sub. I don't think I want to mess with a commercial product by altering any of its circuits / components.
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