Can a change in negative feedback sound better?

Hi Nonoise,

First, the Dakiom device is not changing the amount of negative feedback. It can't do that because it is not within the amplifier's feedback loop. (Although it would be within the feedback loop if the amp were one of a very small handful of designs which I believe exist that use "remote sensing" to include the speaker cables in the loop. Those designs would have "remote sense" terminals that are connected to the speakers in addition to the main speaker output terminals).

Second, I note the following warning at the Dakiom site:

WARNING: THE AMPLIFIER OUTPUT MUST BE ABLE TO HANDLE A CAPACITIVE LOAD OF UP TO 0.08uF. (Best results are obtained with amplifiers that can handle a capacitive load of up to 0.33uF.) THIS IS TRUE FOR MOST CONVENTIONAL COMMERCIAL AMPLIFIERS. WHEN IN DOUBT (SUCH AS VACUUM TUBE, OR UNCONVENTIONAL TECHNOLOGY), CONSULT THE MANUFACTURER.

0.08 uf is 80,000 pf. That is a MUCH greater amount of capacitance than the capacitance of a typical length of ultra-high capacitance speaker cable such as Goertz, which have been known to cause some amplifiers to oscillate and self-destruct when used without a Zobel network. Personally, I would not let such a device get anywhere near my amplifier.

Third, there are two ways I can envision this device making a difference, when used with an amplifier that has a feedback loop. The first of those reasons is, I would expect, likely to be the more significant one in most cases. But I would expect the difference it would result in to be highly system dependent, and to have little predictability with respect to whether it would subjectively be for the better or for the worse in any given system.

1)Depending on amplifier bandwidth, the amount of feedback it uses, and other variables, placing a large capacitance at the output can result at high frequencies in effects that include frequency response peaking, phase shifts, and overshoot and ringing in response to high speed transients. I'm not sure whether for typical amplifier parameters those effects would occur primarily in the upper treble range or the ultrasonic range or the RF range. But it is conceivable that there would be consequences at audible frequencies in any of those cases.

2)The device could act as a filter that would minimize the degree to which RFI or other spurious high frequency energy that may be picked up in the speaker cables might enter the feedback loop of the amplifier, that pickup conceivably having perceptible although unpredictable sonic consequences.

If you already haven't, btw, I would suggest going back and forth several times between having the Dakiom device in place and not having it in place, using the new cabling. Not only to make sure that the Dakiom and not the cabling is responsible for the difference, but to rule out the possibility that differences in contact integrity or other variables might have been factors as well.

Best regards,
-- Al

Al,

As usual, you cut right through the hype and get to the heart of the matter. I must admit that what they claimed about curing negative feedback effects had me wondering since all of that kind of circuitry occurs inside the amp so how could it work after the fact at the amps speaker terminals was beyond my understanding.

As to the possible dangers of using it, I'm now on guard but still feel safe about it since I've used it off and on for a couple of years now with no deleterious effects. In fact, they were always positive until I got the Zu cables, so I stopped using them until now. My newer Mapleshades are past broken in so I don't count them as a variable.

Your first point about the effects of overshoot, ringing, phase shifts, etc. I believe to be, as you mention, in the ultra sonic range or RF as I can detect no negative effects whatsoever but as mentioned, a very positive one on all accounts. Let's hope that is the case here.

I think your second point about how it just may be having an unintended but positive affect in shielding RFI that may be entering through the amps speaker connectors may be it. It uses three connectors (all banana) which connect to both positive and one negative speaker terminal on the amp. I wonder if just putting anything with a banana input would have the same effect as long as it terminated in something innocuous, like the "pigtails" that others have used at their speakers terminals. Those who used them have reported positive sonic results.

As for A/B results, it can drive one nuts but I still hear an improvement, clarity wise. What I get is a cleaner, more focused image which adds to the realism. That's the best way I can put it. I can even hear longer trailing off of sound as a song ends. It's not a hugely significant improvement, but one none the less and it adds to my enjoyment. It just sounds more realistic even as I type this with my head turned away from the music. In fact, when something nice comes on, I've left this seat to go listen to it in the sweet spot.

I think what I'll do next after exhausting myself taking them in and out is to leave them in for some time and then take them out to see if it changes anything for the negative.

As always, thanks for your insight. You're like an anchor of sanity that keeps us from floating away in a sea of sonic uncertainty.

All the best,
Nonoise

I also have been using a pair on my amp inputs for years. When I first purchased them I was using them on a Marantz 1250 integrated amp where they made the most notable difference, for the better. Through the years as I upgraded I found them to make less of a difference. I tried them on a Pass Labs X250 where they made no difference. I have recently been using them on my McCormack DNA-1 and haven't really thought about how they actually sounded. I just put them on because I had them. So after reading this thread I got to thinking and removed them to see if there was a difference. I could detect none. So with the warning Al has pointed out, I've decided to leave them out, and maybe try them on the Marantz 2252 I have set up in the basement. They worked well on the Marantz 1250 and should work just as well on the 2252.
Now I'm wondering about some of the other tweaks I have installed. Maybe I'm just losing my hearing.