Hey guys, so i'm building a classic NE5532 headphone amp, and i need help with potentiometer selection. i have cheap dual gang potentiometers laying around, but i was wondering if it is really worth it to spend money on an expensive one. What is the noise difference on expensive vs cheap ones?
Tracking is one big difference. Give your pot a try, you can always replace it with a better one.
Make sure that your pot is intended for use as a volume control, with an audio taper.
Alps makes good cheap ones. RadioShack sells 100k Alps volume controls for $4. https://www.radioshack.com/products...nged-stereo-volume-control?variant=5717293381
These are good: http://www.ebay.com/itm/like/172025202945?lpid=82&chn=ps&ul_noapp=true
Switched precision resistor controls are very good.
http://glass-ware.stores.yahoo.net/atandsise.html
http://www.ebay.com/bhp/stepped-attenuator
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A Bournes 91 series Dual is what you need. cheap pots are OK for 6 mths or so, but
invariably become noisy as time moves on, and are more likely to be headed for failure
as each day progresses.
Cheers / Chris
invariably become noisy as time moves on, and are more likely to be headed for failure
as each day progresses.
Cheers / Chris
thanks for the replies guys
How many K pot should i use? how many ks will get me the least noise, but at the same time have good audio clarity and detail? Also how much difference will the expensive ones make?
I will give the cheap ones i have a shot, as most of my source equipment have volume controls there, i might just stick on the ones i have, and keep it in one position. Is there any way that i can improve the reliability? (lubrication, cleaning etc.)
How many K pot should i use? how many ks will get me the least noise, but at the same time have good audio clarity and detail? Also how much difference will the expensive ones make?
I will give the cheap ones i have a shot, as most of my source equipment have volume controls there, i might just stick on the ones i have, and keep it in one position. Is there any way that i can improve the reliability? (lubrication, cleaning etc.)
Get one where the track is made from resistive polymer rather than a carbon composite or carbon film pot. The ALPS RK271-series is available from Mouser. Nice pots. Not terribly expensive.
Tom
Tom
How many kohms pot should i use, also how much of a difference does a expensive pot make considering if they are both new?
If the pot has a buffer after it, 10k is fine. If not, it would have to be much lower.
Just don't fall in the trap that they should/will sound different, or "better" .
Better made ones, which of course will be somewhat more expensive than plain vanilla ones (we are talking a few bucks instead of less than a dollar) will be better constructed, track better, be closer to rated value, maybe sealed or having scratch resistant tracks for longer life, all of which is good, of course.
That does not affect sound.
Now going to real expensive "exotic" ones, may or may not be electrically/mechanically better , but that will still not change sound.
Better made ones, which of course will be somewhat more expensive than plain vanilla ones (we are talking a few bucks instead of less than a dollar) will be better constructed, track better, be closer to rated value, maybe sealed or having scratch resistant tracks for longer life, all of which is good, of course.
That does not affect sound.
Now going to real expensive "exotic" ones, may or may not be electrically/mechanically better , but that will still not change sound.
Yeah, but if gets too much lower, the source won't be able to drive it. Tradeoffs, tradeoffs.
OPA1611 buffer -> 2 kΩ pot -> OPA1611 buffer would be my suggestion.
Tom
what should be a good buffer capacitor size? i have some post 2013 3.3uf, 22uf, 100uf and 47uf lelons laying around. i apologize for my noobness, as i don't have much experience with building amplifiers. but i'm sure others will find this helpful.
Do you mean the coupling capacitor before the volume control? For a 10k control, 1uF or more is ok.
If you mean a capacitor between the control wiper and the buffer, it depends on the buffer circuit.
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The coupling cap forms a high-pass filter with the resistance of the pot. The -3 dB frequency of the filter can be calculated as:
f0 = 1/(2*pi*R*C)
R in ohm. C in farad. Frequency in Hz. Just like anything else in the metric system: Base units go in, base units come out.
I'd aim for a cutoff of 2 Hz or below to avoid excessive attenuation within the audio band.
Tom
the NE5532's input impedance is 300kohm, i think the .1hz cutoff will do. thanks for all your help guys.
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