Thanks Jacco. And I am a fluke of the universe. I feel better already, but that may be in part due to the 2003 Lorca Pinot Noir drinking oh so very well.
I apologize to Mr Tarragon, who has after all only attempted to vouchsafe us wisdom, while imperiling his security clearances.
Welcome to the loony bin.
First thing to check is the AC line voltage when you turn on the amplifier. I suspect it may be dropping low enough the amp is unhappy but not broken.
dueling quotes?
pg 180, 7.1.2 Just-Noticeable Level Differences
Psychoacoustics: Facts and Models (Springer Series in Information Sciences) [Hardcover]
Hugo Fastl, Eberhard Zwicker
Publication Date: January 13, 2010 | ISBN-10: 3540231595 | ISBN-13: 978-3540231592 | Edition: 3rd
http://www.amazon.com/books/dp/3540231595
pg 180, 7.1.2 Just-Noticeable Level Differences
Psychoacoustics: Facts and Models (Springer Series in Information Sciences) [Hardcover]
Hugo Fastl, Eberhard Zwicker
Publication Date: January 13, 2010 | ISBN-10: 3540231595 | ISBN-13: 978-3540231592 | Edition: 3rd
http://www.amazon.com/books/dp/3540231595
Last edited:
I think Ed is right about the 1500. If you need further service info, contact Tony@Parasound.com
It is a red herring --- the matching of amp levels --- I gave two examples of hearing problems (1st distortion traced to a loudspeaker's fuse/holder and 2nd an off-center center image due to different path lengths from left-right). Neither need matching of levels to hear. I wasnt trying to know if I hear something or not.
This is an example of a completely misapplied requirement.
Thx-RNMarsh
This is an example of a completely misapplied requirement.
Thx-RNMarsh
Digital amplifier US7286008 ZETEX
A digital amplifier (1) comprising a first modulation stage (9) arranged to receive a digital data signal and to generate a corresponding modulated reference signal; a comparator (12) arranged to receive a feedback signal and the modulated reference signal and generate a corresponding error signal (13) indicative of a difference between the modulated reference signal and the feedback signal; an integration stage (44) arranged to integrate the error signal (13) from the comparator (12) to generate an integrated digital error signal; a summer (19) arranged to receive the integrated digital error signal and the digital data signal (8) and generate an adjusted digital data signal indicative of their sum; an output stage comprising a second modulation stage, the output stage being arranged to receive the adjusted digital data signal and to generate a corresponding modulated output signal for driving a load (7); and a feedback circuit arranged to provide said feedback signal to the comparator (12), the feedback signal being indicative of the modulated output signal.
A digital amplifier (1) comprising a first modulation stage (9) arranged to receive a digital data signal and to generate a corresponding modulated reference signal; a comparator (12) arranged to receive a feedback signal and the modulated reference signal and generate a corresponding error signal (13) indicative of a difference between the modulated reference signal and the feedback signal; an integration stage (44) arranged to integrate the error signal (13) from the comparator (12) to generate an integrated digital error signal; a summer (19) arranged to receive the integrated digital error signal and the digital data signal (8) and generate an adjusted digital data signal indicative of their sum; an output stage comprising a second modulation stage, the output stage being arranged to receive the adjusted digital data signal and to generate a corresponding modulated output signal for driving a load (7); and a feedback circuit arranged to provide said feedback signal to the comparator (12), the feedback signal being indicative of the modulated output signal.
Attachments
probably just less/attenuated output on one side in some, or all frequencies.
thanks for the info tvi, appreciated
Precisely, although I would extend that to include electronics and sources. As has been noted, loudspeakers present the issue of decoupling frequency response from level (both of which are demonstrably of paramount importance to human ears).
The simple experiment I outlined previously will demonstrate this nicely; when I tried it on myself, even though I knew that the differences were level, the 0.2dB louder track still seemed just a bit "clearer" to me. Using the foobar ABX plug-in, I scored 10/12, so the difference seemed significant.
The misunderstanding about perception of small level shifts has put more than one commission check in a hifi salesman's pocket.
It was not claimed, obviously, that it wasn't different. It was claimed that the difference is not perceived as louder.
jan
I'll try again.
In a detection or discrimination procedure the listener is only required to identify the interval that is different or whether two intervals are the same or not. In this case the difference is level. Yes, differences in level can be perceived as differences in loudness. But the subject can use any difference in percept that is noticeable (and they will). At threshold differences, the percept is actually rather subtle and the listener will make mistakes (they are less than 100% but above a rate of chance or guessing). A preference procedure is a different beast altogether.
Maybe my comments will make more sense now. With this in mind, it would suggst that some of the informal observations cited above would in fact create a bit of a paradox.
Although I think the dead horse has been sufficiently beaten
Last edited:
BTW Has anyone here started to read Doug Self's 6th edition? I just stumbled on a great section titled 'feedback intermodulation' (FID anyone?).
He provides, among other very worthwhile things, a solid technical reason why it is indeed a Good Thing to linearise your amp before applying nfb.
(And please, don't start with 'I told you so' - give credit where it is due).
jan
He provides, among other very worthwhile things, a solid technical reason why it is indeed a Good Thing to linearise your amp before applying nfb.
(And please, don't start with 'I told you so' - give credit where it is due).
jan
My pleasure.
(In a couple of months, I'll commemorate Mr Tom Colangelo. How swift does half a dozen years fly by, seemingly faster than an automobile)
Jan ? Jan ? JD, where are you ?
- Status
- Not open for further replies.