Propeller Head Plaza

Technical and scientific discussion of amps, cables and other topics.

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RE: Apparently, I'm just not getting through

Posted by tomservo on June 22, 2010 at 11:13:26:
To be honest, I don’t know what you’re asking for, bare with me here, I am in engineering. When I say insignificant, to me that means something in particular, it doesn’t mean it’s gone but very small.

You ask about measurements, this is how one concludes what insignificant is relative to what your trying to measure, for electrical components I use one of these;

http://www.testequipmentconnection.com/index.php?main_page=search&search=4274A&gclid=CK3Ar9-StKICFQQMDQodfmWg5g

For networks, I use one of these;

http://www.testequipmentdepot.com/usedequipment/hewlettpackard/spectrumanalyzers/3562a.htm?gclid=CKiLiqmStKICFVD75wod2iBA4g

Or a TEF-20 to measure driver impedance curves as with the tower. Also, a network simulator program which with some steering can derive the equivalent circuits for most drivers and deal with a drivers as the load for a filter network etc.

It is relatively easy to measure the signal at each end of a cable too, even using music as the test signal, without a switcher too. That way if one is in doubt about the signal being altered and if it is according to network theory, one can examine the difference and see how close that is to predicted based on measured parameters.

AS for the listening system used back in the cable tests, the amplifiers were several, a threshold stasis (mine) a mcintosh 240, a QSC pl-236, in the amp listening a chevin something and several crowns were added.
The speakers were an early version of a full range horn product used in commercial sound.
The goal (for the last 12 years) was hi fidelity for a large group of people, all the problems one faces get worse as the size of the room increases. My solution was to make a full range horn system where all of the drivers combined coherently into one source with no lobes, no crossover phase shift, constant directivity and high output, all things desirable for home hifi too..
The closest “hifi speaker I have measured “in time” was a manger which was admittedly somewhat better than the SH-50. The SH-50 does go about 30 dB louder, two octaves lower and has about 1/1000 the distortion at livingroom listening levels and does reproduce a square wave “out front” for more than a decade spanning both crossovers. While not aimed at hifi, they are about as close as commercial sound has at the moment and a few have found their way into livingrooms, search here SH-50.
A more typical large scale “hifi” use;

http://audioheritage.csdco.com/vbulletin/showthread.php?26261-IMAX-cinema-sound&p=265081
Best,
Tom Danley