Audio Lessons Learned - post your best advice for the newer members!

Many amps have a HUM issue when "ungrounded" source components, i.e. those with a two pin plug or Wal-Wart power supply, are connected
- my Bryston has this issue, my NAIM had it too

My Bluesound Node 2i, which has a 2 pin plug causes hum if it is the only component connected
- However, my Simmaudio Moon phono stage IS properly grounded
- So when the phono stage is connected in the system - the hum goes away

So WHY does connecting the phono stage eliminate hum?
- because the Node 2i is now being grounded via the neutral side of the system at the amp by the phono stage

So try this ...
- using a piece of wire
- touch one end to the neutral collar of any open RCA socket on a pre-amp or integrated amp
- touch the other end to a mains ground point

The hum should STOP - if it stops
- build a grounding lead by attaching one end to the neutral side of an RCA (or XLR) plug
- attach the other end of the wire to the ground pin ONLY on a mains plug
- plug it into any mains outlet
- plug the RCA into any available RCA socket on the pre-amp or integrated amp

Unfortunately some components that have a two pin plug, sometimes referred to as "fully isolated" can develop a tiny voltage on the neutral side of the circuit, which is often a 50/60 Hz hum.
- Grounding the neutral side ONLY of the entire system will remedy this issue
- If this DOES NOT stop the hum - you have a more serious issue

Regards - Steve

Just because YOU bought it doesn't make it Shangri-La. 
A riff on just because you thought it doesn't mean you should speak it, or post it, or tweet it. 

Short sweet and simple.
Ignore watts.  It is all about instantaneous peak current.

@mahgister,

I think Peter Aczel’s point was that all box speakers always have some tendency to sound like boxes.

Here is his full quote:

"Loudspeakers are a different story. No two of them sound exactly alike, nor will they ever. All, or at least nearly all, of the conflicting claims have some validity.

The trouble is that most designers have an obsessive agenda about one particular design requirement, which they then inflate above all others, marginalizing the latter.

Very few designers focus on the forest rather than the trees. The best designer is inevitably the one who has no agenda, meaning that he does not care which engineering approach works best as long as it really does.

And the design process does not stop with the anechoic optimization of the speaker. Imagine a theoretically perfect loudspeaker that has an anechoic response like a point source, producing exactly the same spherical wave front at equal levels at all frequencies.

If a pair of such speakers were brought into a normally reverberant room with four walls, a floor, and a ceiling, they wouldn’t sound good!

They would only be a good start, requiring further engineering. It’s complicated.

Loudspeakers are the only sector of audio where significant improvements are still possible and can be expected. I suspect that (1) further refinements of radiation pattern will result in the largest sonic benefits and (2) powered loudspeakers with electronic crossovers will end up being preferred to passive-crossover designs.

In any case, one thing I am fairly sure of: No breakthrough in sound quality will be heard from “monkey coffins” (1970s trade lingo), i.e. rectangular boxes with forward-firing drivers.

I’ll go even further: Even if the box is not rectangular but some incredibly fancy shape, even if it’s huge, even if it costs more than a luxury car, if it’s sealed or vented and the drivers are all in front, it’s a monkey coffin and will sound like a monkey coffin—boxy and, to varying degrees, not quite open and transparent."

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I’d like to think that he did consider the subject of rooms and placement in detail. He just didn’t like what cabinets tend to do to the sound of the drivers.

To my ears ported speakers sound easier on the ear than sealed box ones do. On the other hand many dislike the effect that the port (hole in the cabinet) usually does to the bass timing. As ever with loudspeakers you have to chose the compromises that you are most able to accept.

Peter Aczel with a lifetime of experience behind him finally settled on boxless designs like the Linkwitz Orion and the LX521 both which placed the midrange driver on a backless panel, much like what Stewart Tyler had also done with one of his ProAc designs.

Aczel also liked omnidirectional designs like the Bang & Olufsen BeoLab 5.

Here’s his preface to a 2005 review:

"I have a dream. I dream of the Ultimate Loudspeaker. It can only exist in my dream because in the real world no manufacturer would have the overarching vision and multifaceted expertise to incorporate each and every one of its ideal features in a single design. No way; it could never happen.

It would of course have to be a powered loudspeaker because perfect matching of the amplifier channels to the drivers is possible that way and because separate, free-standing power amplifiers are hopelessly twentieth-century.

It would have to be a 4-way loudspeaker because 3-way design always stretches the capabilities of the drivers to the limit.

It would have high-order digital filters in the electronic crossover because they are linear-phase and just plain superior. The four power amplifiers would be extremely powerful yet small enough to be tucked unobtrusively inside the speaker enclosure, thanks to the most sophisticated switch-mode design.

The various functions and protection modes of the speaker would be controlled by a powerful internal computer and DSP processor, which would also permit a single digital S/PDIF connection from a stereo signal source to produce music from the all-in-one amplifier/speaker system.

One of the capabilities of the DSP would be to tune the bass response of the speaker to its specific location in the listening room. (I can dream, can’t I?)

Also, the midrange and treble response of the speaker would be much wider in dispersion than the usual 60° or 90°, extending essentially to 180°, so that the location of the listener would become totally unimportant. (Asking for the moon? What are dreams for?)

Am I still dreaming? What are those two strange-looking monoliths in my listening room? Could they be loudspeakers? Introducing the Bang & Olufsen BeoLab 5, the speaker that makes my dream come true in every detail, bar none. I can hardly believe it. Amazing. Speakers will never be the same again."

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If you have been able to overcome the long recognised limitations of cabinet loudspeakers then good for you.

Perhaps you can help the rest of us attain some of your success via embedding, but I don’t think it’s fair to suggest that loudspeaker cabinets do not present certain sonic issues.

https://www.biline.ca/audio_critic/audio_critic_web3.htm