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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Re: Too low vol setting bad for dynamics ? posted by zanash on July 25, 2005 at 23:11:55:
>That said a little tweeking and some good quality components certainly raise the >performance from ok to top notch
Sure. Sad you cannot tweak the layout, that's were most improvements can be made (parallel layout of current loops, guarding high impedance tracks, separate layout of all grounds, decoupling between source IC or discrete transistors power lines, and FB return of following stage, highest possible components density - with thermal behavior sims obviously- etc etc.) You soon go to the point where a 2-layer board is just not enough, and you 'll use a four-layer board for good planes above the tracks and components that need it.>Once the cheap pots are swapped out for say a Bournes conductive plastic
>of the same value the unit realy start to sing.
A common problem with cheap pots is that the wiper, rubbing onto the conductive track, tears off small particles and dust from the conductive material. There are two contradictory constrains for the pot designer; applying a light rubbing pressure (to avoid eating the track too fast), but dust will accumulate under the wiper, increase the wiper resistance, and give bad sound (because the dust resistance is non-linear, as for most percolating systems). Or appying an high pressure, but you eat out the track sooner, and the pot won't last long. For treble and bass controls mainstream designer use high wiper pressure pots (most are linear BTW), as they guess the pots will be used sparcely, for the volume pot, they use low pressure pots.
Or, the best solutions are:
-using a hard track material, and apply a high pressure. That is the Cermet pots case . Cermet is a mix (up to the nanoscale) of metallic oxydes -ceramics- and a conductor (tungsten, molybdenum or allied silver). People don't like them in audio circles, I don't know why, all my pots are now cermet, and I'm happy with them
-using a supple, "lissom" material, that will grow hollow under the wiper pressure then get back to its initial shape. So, no tearing off dust particles. That's the conductive plastic pots you were talking about.
>I know this from work done on several mass market integrateds I've modded. Once the
>cheap pots are swapped out for say a Bournes conductive plastic of the same value the
> unit realy start to sing.
;-)
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Follow Ups
- Re: Too low vol setting bad for dynamics ? - Jacques 12:40:56 07/26/05 (2)
- Re: Too low vol setting bad for dynamics ? - zanash 04:02:10 07/27/05 (1)
- Re: Too low vol setting bad for dynamics ? - Wally 10:36:00 07/27/05 (0)
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