I still have not found the correct name for the complex wave that contains an infinate number of odd and even harmonics. I asked an FCC certified field engineer that is old enough to have gone to school with Marconi, and he said the best way he could explain it is this:

You will have one mell of a hess displayed on the oscilloscope..

So I guess it is not a back-to-back sawtooth...Oh, well....

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When the driver diaphragm is changed, use a non-magnetic screwdriver. If not, that powerful magnet will displace the position of the screwdriver tip - and will punch a hole in your brand new one. Been there.....

In fact, all of the "Rane Notes" are interesting and quite informative. If you haven't read them, you should!

Steve

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: here

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"It has to be understood that analogue components do not simply go into hard clipping from a certain point onwards, but that the signal gets more and more distorted as this point is approached".

This really depends on the design of the analog equipment. If you are talking about a CP200 (which was designed back in the late 1970's), yes this is true, but modern analogue equipment is quite different.

For instance, the THD of a current QSC amplifier (or a Panastereo sound processor) falls until the point of clipping is REACHED, rather than APPROACHED. The problem with older equipment, relates to the method of gain control, rather than the absolute level of the input signal.

Modern, high performance analog equipment will produce reducing distortion until the actual level of clipping is reached, and thence forth, (like digital) will severely clip.

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Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

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Once again to be more accurate, in modern analog equipment distortion stays pretty much constant up to the point of clipping, it is the noise level which falls compared with the signal level, so it is the combined THD+N figure that falls as the signal level rises.

My reference to gain control methods is aimed at the once common use of VCA's (voltage controlled amplifiers) which have the characterisic of increasing distortion as the signal level rises. I hate those things!

Now, regarding equaliser settings, I would agree wholeheartedly that a poorly setup system will increase the risk of distortion. However I would have considered the same problem to exist for analog equipment. So Michael I don't quite understand what you are getting at.

BTW Michael your English is very good. If a dummy like me can understand you, then you are doing very well indeed.

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Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

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QUESTION: where cinema applications fit here ? category one , as in studio recording ?

JBL itself if some of its cinema appl papers recommends amps with twice the IEC rating, for instance on the 5000 serie. For the subwoofers, they recommended 1xIEC and multiply the subwoofers to increase SPL pressure rather (doubling the nr of stacked subs yields about 4-6dB).
also, the volume of the room is a direct influence on the power required and the number of speakers of course (especially subwoofers for instance). And power compression intervenes at some time also.
I often read here that it's better to increase the number of subwoofers to reach those 105 or 115db SPL at 2/3 the distance rather than increasing the power feeding them.
Also, equalizing which sometimes requires a boost at certain frequencies creates needs for more amp headroom and thus bigger amp or more use of bridging.
David