Years ago I bought noise filters that go on the negative speaker lead. They are black tubes about 6" long. They came from audio Advisor and were called Pigtails. Anyone familiar with them? I always wondered how they could do anything since they only connect to the negative speaker terminal? Thanks, barondla
I've never heard of that particular item. But I do know firsthand there is speaker ground noise in amps that isn't noticeable until it's completely removed.
Seems like I remember seeing these at AA. I have been a semi-regular buyer from them and received their flyers since 1995. Have not seen them in years and I have their fall 2022 catalog here so I take it they did not live up to expectations. From what you describe about hookup they may have some kind of a diode in them to prevent back feeding, but who knows?
Thanks for the memory upgrade! Seem to recall a blurb about speaker causing back force into amp. A fancy diode might stop it. Even though they only hook to the negative terminal, they definitely affect the sound. System sounds brighter, a little gritty, and voices sound thinner without them. I'll leave them on. Thanks, barondla
There is nothing you can put in line with your speaker leads which can filter out noise without having some negative effect on other desirable aspects such as damping factor. You want the back EMF from your speakers to go unhindered back to the amplifier outputs - you do not want to filter that out! That is how your amplifier controls the damping of your speakers and is a desirable thing. Speakers cannot generate "noise".
You could put a C and L in series The C would block DC and the L hi freq But to get any meaningful benefit in the audio range it would impact the whole range to some degree. Xc = 1/(2 Pi f C) Ohm Xl = 2 Pi f L Ohm
When I was a kid, my parents always used to complain about the noise coming from my room. Since I was listening to Stockhausen, that wasn't far off the mark.
This is my 1000va transformer installed between my SDA speakers which is necessary so my monoblocks don't "see" eachother. An unintended side benefit is a significant reduction in ground noise even when using a single amp. It was and continues to be an eye opening upgrade.
Most everything I listened to as a teen was noise according to my dad. Unless it was Robert Flack or Tina Turner.
00 Could somebody please tell me, as an apparently ignorant engineer, what ground noise is in the context of speakers? I'd be particularly keen to know what it is when using bridged/balanced amplifier output stages (many if not most SS amps are) where neither side is 'ground'.
This is another thing that confuses me. The Pigtail's single spade lays on top of the negative speaker spade lug. The signal doesn't travel thru the Pigtail to get to the speaker terminal. There isn't an in and out on the Pigtail, just one spade connection. So it is hooked in parallel with the negative speaker terminal. With no in and out pass thru and no + connection, I don't understand how these work? Wish I still had the Audio Advisor catalog these were ordered from. Unfortunately that was about 20 years ago. I know the speakers sound more natural with them attached. The amp I'm using at the moment is a PS Audio S300 fully balanced class D amp. Impressive filter @motorstereo . So it's optional or your system won't work at all without it? A friend had transformers on his Lowthers, but I think it was to reduce a peaky upper midrange. Thanks, barondla .
Yes never let amps see each others output......meaning do not connect the monoblocks speaker outputs to each other.
Why would anyone connect the outputs of monoblocks together? The whole point of running monoblocks is channel separation. It’s an inherent advantage. What you’re doing provides zero advantage, it’s actually a detriment if anything.
I’m guessing it’s so one speaker’s cones aren’t influenced by the other ones sound pressure with regard to back EMF that isn’t from itself?
Sorry I can't help you on what the noise sounds like but surely you must know when bridging amps noise goes up, df goes down, the impedance the amps see is halved and for the most part the amps just don't sound good. But the power is increased if that's what one is after. No; it's so the non common ground amps or in my case monoblocks don't see eachother's output. Without this transformer in place I would not be able to use the amps I'm currently using (mcintosh mc1201's).
So you’re using it to increase the impedance the amplifiers see. But if both speakers are connected to that transformer box, what you’re actually doing is negating some of the isolation between the monoblocks. I can’t imagine how it would possibly improve isolation but I admit I haven’t attended the College of VooDoo Engineering.
No it does not increase the impedance of the speakers and there's no "voodoo" involved. Polk makes a version called the A1 interface which also allows the use of non common ground amps and monoblocks. There's also an 800 va version of the 1 to 1 transformer. I'm using the 1000 va Avel Lindberg transformer which I picked up a few years ago from a group purchase with several other SDA speaker owners. If you're actually curious head over to the Polk forum as there's plenty of reading to be done complete with charts and measurements. Search for "dreadnaught". As I mentioned the use of this transformer is clearly audible even when using a common ground amp that can be used with a stock interconnect. Yes it surprised me as well that there is obviously ground noise that up until that point was inaudible.
While I don't doubt for a minute the benefits you cite, being a curious engineering type, I'm curious what this 'ground noise' is. I think it would be interesting to do some instrument testing to sort out what is going on. What this would do is by isolating the problem, allow control over it. I know you say it's covered on the Polk forums, but finding real technical information (as opposed to marketing department blather) is difficult, especially on non-technical forums. By the way, the amplifiers we design and manufacture are all (like most solid state amplifiers these days) balanced designs with neither speaker terminal 'ground'. There are many reasons for the migration to this type of design, a lot having to do with efficiency of one type or another.
