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I am looking for a stepped or other good quality attenuator/potentiometer to replace the one that came with my Fi Y preamp. The one I have in the Fi Y is pretty good at normal volume settings but the tracking between channels is off for very low settings (up to 6dB difference between channels). Since most pots have that problem I am looking for a better quality solution.The problem is that there is very LIMITED space in the Fi Y pre, and it only allows an attenuator that is 25mm or 1 inch deep/long. Most stereo stepped attenuators (Dact CT2, Goldpoints Mini-L, etc.) are more like 40-60mm long. Even a TDK P2500 with 27mm for the stereo pot is just a little too deep :(
Any suggestions?And thanks to everyone for their help....
Rene
"I wouldn't trust (no) words written on no piece of paper."
Jim Jarmusch, DEAD MAN 1995
Follow Ups:
.
Yes, my Fi Y has two inputs with reduced gain. Don uses resistors in series for the attenuation of these two inputs of only a few db. per Don's suggestion I could exchange the resistors for these two inputs to have more attenuation.Also, on the side: Don mentioned that he is usually listening around the 9 o'clock position as well (using a 2V source): The large gain of the Fi Y together with the input sensitivity of the X puts you in a regime where you do need strong attenuation for regular listening. I read in some post here that some people use the passive attenuator switch on the Fi X (if installed) to reduce the gain somewhat.
Many thanks,
Rene
"I wouldn't trust (no) words written on no piece of paper."
Jim Jarmusch, DEAD MAN 1995
I don't like the idea of adding a lot of series resistance to get the signal level down, but you can minimize it if you use a much smaller pot too. For example, if your current pot is a 100k unit, then you could replace it with a 25k unit and put 75k fixed resistors 'on top' of the pot. This will let you use the pot up where the tracking is better.Unfortunately, the fixed resistors will probably add their own flavor to the sound (though you're probably used to this without knowing it if you've been running down around 7 - 9 o'clock'; the sound of the pot itself...) You might want to choose good resistors. I have no experience with expensive resistors, so I can't recommend any. Personally, I have always preferred wire wound, but it's hard to find them at that high value. (Gary's post on LED biasing had me shaking my head in agreement. :-)
As a quick fix you could try adding resistors of 2 or 3 times the pot value in series before the pot - just what Don recommended. At least that will let you run where the tracking is better.
Dave, thanks so much for your comments. I don't quite like the idea of running a larger resistor in series either, although this is pretty much what some of the tube preamps use to reduce the large gain from 20dB to 12db or so (e.g. Wright, Fi, etc).
Unfortunately, the fixed resistors will probably add their own flavor to the sound (though you're probably used to this without knowing it if you've been running down around 7 - 9 o'clock'; the sound of the pot itself...)I have to say though that "pot" sound quite good. I can't complain about the overall sound of the Fi Y at all.
As a quick fix you could try adding resistors of 2 or 3 times the pot value in series before the pot - just what Don recommended. At least that will let you run where the tracking is better.That is probably the way I might go for now. I just haven't decided on whether to add the higher value resistors internally, or to add the adjustable Endler attenuators up front. The Endler would give me more flexibility (I could even just use them as a passive) and it uses fairly good and channel matched resistors as well.
Thanks again,
Rene
"I wouldn't trust (no) words written on no piece of paper."
Jim Jarmusch, DEAD MAN 1995
"I wouldn't trust (no) words written on no piece of paper."
Jim Jarmusch, DEAD MAN 1995
Leaving all high gain problems aside, I am wondering whether I can at least "gain" (pun intended) some quality and improve on the standard pot.The current pot tracks to about 0.5dB through most of the range, not stellar, but o.k. The question is can I improve on that?
Two attenuators that are less than 25 mm deep I found are:
- ALPS Blue Velvet (3.0dB)
- TKD CP-601 (about 0.6 to 2dB tracking dependent on attenuation level)Looking at the tracking number I think either one will only be a slight or no improvement for channel tracking. Anyone out there with experiences for the two pots? Is there any other sonic benefit using one of these two?
Thanks again for everyone's help.
Rene
"I wouldn't trust (no) words written on no piece of paper."
Jim Jarmusch, DEAD MAN 1995
.
when I've compared Alps blue velvet to a law faking pot, the latter sounds better. Mind, if you can get a linear Alps pot, that's OK. Go for law faking soundwise if you have limited space. Not sure if tracking will improve, though.
Well, I measured my current potentiometer for tracking differences in the listening range:position tracking
7 o'clock start
7-8 3.5dB
8 0.5dB
9 0.1dB
10 -0.3dB
11 -0.4dB
12 o'clock -0.5dBThe question is: Can I improve on these numbers using a better potentiometer or a stepped attenuator? At least for the main listening range 9-10 the tracking is pretty good, but does the difference for the other settings warrant an upgrade and can I expect improvements? That is of course if I can find a potentiometer/attenuator that fits inside the Fi.
Thanks again for everyone's help on this.
Rene
"I wouldn't trust (no) words written on no piece of paper."
Jim Jarmusch, DEAD MAN 1995
Hi ,
You could always parallel up a pair of resistors from the wiper to 0V . A bit of a bodge really but may get you out of the situation . Alternatively blank off the pot hole and use an external attenuator .cheers
Hi.you just stated you did not recommend attenuators located OUTSIDE
of the amp because of cable capacitance, blah blah. Need I point out which thread was it?So which of your statements of this same subject is correct ?
The piece of equipment would be better working rather than having imbalanced channels . Can you help the poster by choosing a decent attenuator that would fit in the space ?cheers
Hi.Learn from those talk with a brain. Dave Slagle just showed you an
excellent axmaple. You did not read it?
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