Interesting day! (maybe not interesting to read?)

Tenson said:
If you have a live acoustic recording and play it back through a flat, flat system it will sound the same as it did live.
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No it won't. Your 'flat, flat system' would have to have negligible harmonic and intermodulation distortions at all levels. It would have to be capable of playing at full, dynamic levels and be effectively silent during the quiet bits. It would need perfect attack and decay characteristics and no phase errors. The room would have to be perfect. Even then, it wouldn't sound the same as it did live because the sound dispersion of the speakers differs from the actual dispersion of the instruments.

All this assumes a perfect recording of course.

A flat frequency response is only part of the story.
 
i reckon i've a reasonable room to try one of these things in (small room/largish speakers) - 300ukp for the prosound 19 rack thing doesn't seem too unreasonable and i could always sell it on.

the thing that puts me off is what with all those knobs to to tweak,microphones,frequency response charts to look at and the like, i'll stop listening to music. i get limited time to that these days so i think i'll pass.

I found the settings on a rel more of a distraction than anything else .
 
Hi,

7_V said:
The Fletcher Munson curve is simply a graph which demonstrates that hearing is more sensitive in the mid-band than at the top or bootom of the audio frequency range. From this you can't imply that you shouldn't EQ to flat.
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Yes, but first of all, the F/M Curves are inacurate (more modern measurements show the differences are not as large as F/M suggest), secondly, for some reason people insist on creating Loudness circuits that follow the F/M Curves, instead of the DIFFERENTIAL between them (or rather more modern "equal loudness" curves), which requires only an LF boost, no HF boost....

The amount of the LF boost is for 60db attenuation (referenced to 90db SPL a good "realistic" playback level for slow average reading) is around 20db @ 30Hz and for 30db attenuation (60db average SPL which is rather quiet) is around 10db @ 30Hz, when attenuating by around 20db (70db average SPL) only around 3db LF boost @ 30Hz is required.

So, unless you listen very quietly no EQ is needed to make up for "loudness difference".

HOWEVER, a truely flat LF response still does not work. That is because in most studios they mix on speakers that are not flat, which is why a really good stereo needs an Equaliser, to make up for the differences in the actual recording, which has been mastered using "monitors" that give an inaccurate indication of LF (and often MF & HF) Levels in the recording and tend to be compensated for by the Engineer in error.

Mark Levinson (the Man, not the company) did some studies and found difference of up to 20db at the frequency extremes between different "studio monitors", all these being large format main monitors, not Yammie NS-10 and Beep LS3/5 nearfield jokes.

(BTW, for the Analogies here, different premphasis EQ's which persisted in use well into the 1980's also mean that records can have up to 9db differences in frequency response from flat, when replayed via the RIAA curve, the upcoming Music First Audio Phonostage will allow the selection of the major EQ curves to compensate)

The best EQ for Music is still the Cello Palette, but sadly long discontinued (I have a crazy plan to bring back a valved variation of it as analogue mastering EQ for Studio and Home use via Music First Audio, but that is still a good deal in the future, a "super purist" Microphone preamp is first after I finish the work on the Phonostage).

However something like DEQ8024/2496 can be used instead, especially the DEQ2496 with it's rotaray controls for "paragraphic" mode is great, sadly you need the Firmware upgrade loaded to allow the DEQ2496 to be used in subtractive/additive mode to make this really usefull, right now I have nothing MiDi so the upgrade waits to be loaded on my DEQ....

Ciao T
 
Hi,

BTW, speaking of EQ usage, this article by Dick Burwen on his then rather revolutionary digital program EQ is quite interresting:

http://www.burwenaudio.com/images/Audio_April_1995.pdf

I wonder when I can use the Waves Active X plugins with Windows Media Player or does anyone know a good Software Player with Monkey Audio or L-Pac support that supports these Plugins?

Ciao T
 
just out of interest ( puts hand up at back of class )

eh hem.....excuse my ignorance but would pink noise give more accurate musical results for tests as it is closer to normal harmonic music ?
 
Pink noise does not have a flat power response, so not suitable for measuring, unless a pink noise weighting filter is used at the input of the measuring device I guess..
 
Pink noise is good for real time analysing as you get more low frequency information, but if you are going to take, for example, a 10second sample, you may as well use white noise that has equal power per Hz. It is also just a pain in the arse to try and look at something which is slanted on a graph but in reality it is a flat response.
 
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Hi,

darrylfunk said:
anyone ?
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Well, given the recent objections from a range of sources about me being a stickler for actual facts and such incovenience, I averted comments.

Simply speaking, any number of signals can be used as "supposed to be". As long as you know what you expect you can use any number of methodes to derive from that and the signal received the difference, in other words how far the "is" deviates from the "supposed to be".

Pink noise, white noise, gray nois, purple noise, impulse, Maximum Length Sequence et al....

Of course using white noise where you expect pink may give trouble.

Ciao T
 


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