Welcome! Need support, you got it. Or share you ideas and experiences.
Way back when, Mart & co. provided me lots of info on Zobels. Curiosity about possible benefits bit the tweaker part of me and I went for it. Values used were as recommended by Mart: 8ohm resistor + .47uF cap in RC config plus a .01uF bypass cap.
As a result of parts sources, I first tried AudioCap Thetas + Mills resistors (and Mart's suggested RadioShack disc cap for the bypass). After about 150hrs I ended up abandoning this combo - as I couldn't hear any difference. Nothing negative resulted so I could have left them in for RF rejection I suppose but went on to wait for my next try at this.
It took awhile to get the Jensen PIO's (including bypass value) and esp. the Caddock Power Film resistors (had to wait for a production run!). But eventually I had everything and wired them into the external XO box of my modded 1.6's. There were some subtle changes - not all for the better (sound stage depth loss, less liveliness). Resisting the urge to pull them out right away, I hung in there - these took a long time to burn in! The Jensen's I was familiar with from the XO build but this combo took a long time > 300hrs. Not sure if this was due primarily to the Caddock's (talk about huge resistors) - also whether burn in was exacerbated with the unavoidable mechanical insertion (wire, etc) into the XO.
Good news is that the Zobel's have had a beneficial albeit subtle effect. Most notable on the highs: a greater sense of clarity, a *cleaner* sound (as if a slight smearing or ringing effect not noticed before has been removed). Cleaner is the word I would use overall, even into the bass - like the edges of the transients are more clearly defined, more solid. - resulting in better tonality (as well).
As for value - parts were premium. My limited experience is that they're needed. I would surmise that lesser quality could have negative side effects. Mileage will obviously vary with system synergies.
I'm running 24' JPS biwire Ultra's - as my equipment is on a side wall and the 1.6's along a long wall - so I don't know what part cable length factors into this. I will leave the knowledgeable explanations to Mart and co.
Now that these seem to be burnt in... onto my next project, building an AN DAC1.2 kit.
So, what did you finally decide which worked in your system best? Did you mount the bypass cap just the across the cap or the entire Zobel?
» moderate Mart £ «
Tx again for all the info and patience you exhibited in helping me with the options available.
I settled on the Jensen PIO's (used the more economical aluminum PIO's) and the Caddock Power Film resistors. As for the .01uF bypass cap (also a Jensen PIO) I ended up settling on the cap across the .47uF cap. This was much harder to decide as it's effects (benefits) bordered on the neurotic perceptions of this listener. I started out with it across the entire Zobel as it nicely bridged the +/- speaker terminals, switching back and forth after long listening periods (days) but found myself always coming back to the parallel cap configuration. Certainly it was not an obvious choice, as was the Zobel in general where I could determine the audible benefits with certain musical material. Call it voodoo intuition or subconscious predisposition. (If it's that close, is across the Zobel the theoretical preference?)
This is not one of those night and day tweaks - at least in my system. But being as anal as I am, felt the investment in these premium passive parts worth it.
It is good you're getting postive results from your experiment.
I remember trying something similar a few months ago using a 0.1uF cap and 10 Ohm R combination. At that time, I also heard smoother highes with less grudge. The midrange also took on slightly more depth with an expanded soundstage. While I found these changes positive, I also heard a slight loss of pace in the upper bass region that made the music less engaging overall. Disappointed, I had removed the zobel after several days of listening.
Since then, I've made a couple of changes in the system including new tubes in the front end electronics. I am tempted to give it another try even though I can think of no technical explanation to correlate what I was hearing.
BTW, the parts I used were quite ordinary, polyprop cap and carbon resistor.
Happy listening... and thanks for reporting your results.
My experience was similar once, in my instance, I went from polyprops to PIO's and film resistors: initially, apparent *cleaner* highs but with a slight loss of liveliness (or pace, as you phrased it).
That loss of pace was restored once (even improved) the components burned in - a very long time at that in this instance (as bad as IC's and wire can be).
The question I don't have definitive answers for is whether the improvement in my system resulted from the PIO's, resistors or the combo with the film resistors - I suspect the PIO's have a large part in this. If, when I have another round at this, I'll swap in the Mills resistors with the PIO's and see what part the resistors play into this.
... since foil & wire wound resistors do exhibit some inductance in the RF region which
However, I wanted the answer documented in this thread while we both remember. If anything else regarding this experiment comes to mind that can be of use for future reference don't please hesitate to add it.
» moderate Mart £ «
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