And that's more than 25 years at this point. Harmon is currently producing some of the best speakers in the world. Real engineering actually advances the art, if not the fashion.
Thanks for your reply.
This particular unit is approved to UL1283. The scope is "These requirements cover electromagnetic interference (EMI) filters installed on, or connected to, 1000 V or lower potential circuits, 50 - 60 Hz, or up to 1500V dc, and installed in accordance with the National Electrical Code".
Not being based in the US I am not overly familiar with the NEC so I don't know if that scope statement implies they would meet the safety bonding requirement.
I take your point that, by definition, if the earth line choke has sufficient impedance to be effective at isolating the 50Hz ground loop currents then it could not pass the safety bonding requirement.
The two variants use 0.4mH and 0.1mH which have an impedance of 0.15 and 0.04 Ohms at 60Hz so they might comply with that requirement
My application is the nasty world of EM compliance - this style of filter is a useful addition to the armory.
I am referring to the JBL of over 25 years ago. However, they do make some hi end components that look pretty well designed, and all this without Floyd Toole.
Yes, now they have Sean Olive, his protege. Similarly focused on real advances and solving real problems.
Notice the rejection plots. Rejection below about 20KHz is going to be low which means line harmonics won't see much rejection.
They are helpful for AM radio and some brands extend the plots up into the hundreds of MHz which shows they may be good for FM and some TV rejection.
They are helpful for AM radio and some brands extend the plots up into the hundreds of MHz which shows they may be good for FM and some TV rejection.
Yup. I need new IEC's for an app that has a D amp, so figured to use one to keep hash at bay.
But yes, it will do nothing for ground loop induction in the audio band.
jn
With all the garbage on power lines (in the USA at least) they do serve a purpose. I've used them in my last three amps and believe there is some reduction in background noise, although I've not done a comparitive measurement.
Just get me a pair of JBL M2 Reference Monitor speakers and I will be most happy! '-)
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What would Dave say! They aren't even fashion priced $9999 amp and speaker together.
They might compete with what Dave makes. They probably have an inferior cabinet construction, but their drivers are first class. Of course, I could hardly afford them, myself, so I am deeply grateful that Dave gave me the Sashas. Dave's cabinets are magnificent!
Yes.
Do you remember the “ ‘Acoustically small’ bass enclosure” (or something like that) article in WW?
George
Hang loose, man ... 😛
MP3's are the whipping boys of music, like Bose in manufacturing, 😀. My personal experience is that if they are competently encoded, at high bit rates, and decoded into uncompressed files before playing, that they are highly satisfactory as music tracks - but if you deal with them as a junk medium, then that's exactly what they will sound like ... enter, from stage right, the Compact Cassette ...
Noise is never stripped from the source signal, unless you throw lots of DSP at the exercise - but you aim to improve the ability of the playback system to render the subjective impact of that noise to be as little as possible. IME, this can be done ..
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I heard a pair of ambitious JBL home audio speakers, driven by Accuphase amplification, at that hifi show and was quite surprised by its poor showing: at low levels it was quite reasonable, but once decent volume levels were called for it became quite shouty, it was rapidly heading into typical PA territory ...
On equipment that I install it utilises chokes on the ground similar to what you explained. The purpose is to arrest transients generated from high current contactors when the coil is energized or de energized. The transients cause the digital control boards to reset. Placing the chokes eliminates this. The machinery has passed UL standards with the chokes in place. Think the value is 4 mH.
Anyway, my point is that the machined is manufactured in Germany and connected in the US. UL standards govern this, not NEC. NEC is for building codes and what is installed in buildings for safety, not machinery or appliances.
I would use them with no problem for chassis to ground isolation. It is still a direct connection to ground for short circuit protection and absorbs undesired noise from ground loops and transients.
I have heard JBL's sound as good as anything at a CES show, and for the money, they are a real bargain. But they have to be full size with the highest quality drivers that they know how to make.
Now, REAL LOUD, like Grateful Dead levels, perhaps Meyersound would be a better choice.
Now, REAL LOUD, like Grateful Dead levels, perhaps Meyersound would be a better choice.
Thanks for your explanation - your reasoning is clearer to me now
Yes, I forgot the impedance swings of the speaker interaction with the speaker cable impedance in theory accounted for the small timing differences in the speaker ramp up time for different frequencies across the audio range.
Correction, they weren't home audio products - JBL’s 4429 Studio Monitors were the ones. We're not talking ear-shredding levels - just at reasonable SPLs, getting closer to an acoustic instrument's output.
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