Potentiometers: Ladder, Series, etc....


As kind of a follow up to the "what is the best resistor thread", can someone please explain the differences between various styles of attenuators ? A brief explanation of their basic high and low points i.e. "ultimate resolution" vs "complete circuit stability / loading characteristics" factoring in such things as cost, ease of construction, etc.. might be a nice point of reference for others to learn from. If possible, please try and keep it simple so that EVERYONE can follow along. Me included : ) Sean
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sean
Great response from Poorguy--it leaves me speechless. Well, almost. You'll find a few people, dealers mostly, who claim that best potentiometers beats best stepped attenuators of any type. But I think most experts would vote for ladder type stepped attenuators, in which there is a single series resistor and a single resistor to ground at each setting (as opposed to series stepped attenuators, in which there are roughly as many resistors, series and ground, as there are steps, so a lot of solder joints for the signal to pass through). I've made both series and ladder, both using Holco resistors and excellent switches, and can easily hear the superiority of the ladder type. Still, some very prestigious preamps, like at least older ARC and all the CAT's, use a series type. That's one reason why I sold my CAT SL-1 III, despite its having a factory-simplified signal path: it was much less transparent than a ladder type passive preamp I made myself. Whether a passive or active preamp is best is another contentious issue. But in any preamp using a stepped attenuator, I'm prepared to say without fear of contradiction (or at least I won't be moved if someone does) that ladder beats series by a country mile. There's a shunt type too, which I've never heard. Unlike all the other types, it presents a different input impedance to the source with different settings.
THANK YOU for both responses. Both were quite informative. While i would tend to agree with Tom's opinion that the Ladder design should work best ( at least in theory ), i have not ventured into this area as of yet. I've been toying with it for quite some time, just never got around to it.

Out of the "mass produced" dual ganged stereo pots, what do you guys like best and why ? While i'm not against spending a reasonable sum for a stepped attenuator, "bang for the buck" type of products tend to score high in my book. A few suggestions along those lines would also be appreciated. I'd simply like to compare my options and then go from there. Sean
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