question about Para/EQ

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tdangelo

question about Para/EQ
« on: 22 Jul 2005, 08:45 pm »
Hi, was wondering IF raising frequency levels with Para/EQ much above 0db can produce digital clipping like raising the correction curve much above 0db?  Does that make sense  :?

Thanks

Tony D.

zybar

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Re: question about Para/EQ
« Reply #1 on: 23 Jul 2005, 08:03 pm »
Quote from: tdangelo
Hi, was wondering IF raising frequency levels with Para/EQ much above 0db can produce digital clipping like raising the correction curve much above 0db?  Does that make sense  :?

Thanks

Tony D.


Tony,

I haven't played too much with the Para/EQ feature, but I expect it would be the same as raising the correction too high.

I know that Eric has played with the Para?EQ quite a bit, maybe he can chime in with some facts vs. my speculation...

BTW, depending on the frequency range, width of correction, and the amount of correction, you can raise the correction to bring you over 0.  You just need to be careful and not over do it.

George

ryno

question about Para/EQ
« Reply #2 on: 23 Jul 2005, 10:30 pm »
I have a behringer  DEQ2496, optical in/out. When I raise an EQ band above zero, the output clipping light goes on. When I drop the overall output level to the same level I raised the EQ band, the clipping stops. I don't know if it's "really" clipping or what, thats just what happens with the behringer.
Are other digital EQ's like that?
Ryan

ekovalsky

Re: question about Para/EQ
« Reply #3 on: 27 Jul 2005, 06:51 pm »
Quote from: tdangelo
Hi, was wondering IF raising frequency levels with Para/EQ much above 0db can produce digital clipping like raising the correction curve much above 0db?  Does that make sense  :?

Thanks

Tony D.


Tony,

Technically with digital you cannot raise signal above 0dB.  Boost at one frequency is accomplished by leaving its level unchanged and reducing the levels of other frequencies.  Really this is no different than with analog EQ, the difference being with digital you will have to turn the amp volume up to keep levels the same.  With analog, the the volume levels will be maintained but you'll run out of headroom at the boosted frequency before turning the volume up as high as you previous could.

That said, many recordings don't have maximum signal levels over narrow (high Q) frequency bands.  For these, a high Q digital boost of 2-3dB is usually possible without causing audible clipping.  However, if you have a recording that does have full or near full level signal at the frequencies you are trying to boost (very common with modern compressed pop recordings) clipping will be present.

Any boost within the RCS, whether from ParEQ or a correction filter, will have the same effect.  My TacT correction filters max out at under +2dB at 55hz, where I have a troublesome null.  I have seen the clip light of the amps come on rare occasion but it is inaudible.  The "clip" light on the RCS reflects the incoming signal, not the processed signal, and it frequently flashes with compressed recordings whether on a correction program or in bypass mode.  

ParEQ can handle most bass issues alone, and I got very good results using it with my current speakers sans correction.  

If you are going to be using ParEQ, you may find this bidirectional Q-Octave calculator of use.

PS -- If I got overzealous with the wrench on the RM40s, as GrandMaster "B" implied, I apologize.  I don't remember any of them ever being loose, nor do I recall you mentioning it in the nearly two years you've had the speakers.  I only used the main two sets of posts, so if it was one of the extra pairs they came that way from the factory  :)

tdangelo

question about Para/EQ
« Reply #4 on: 27 Jul 2005, 11:01 pm »
thanks for the info guys - I kinda figured thats what the Para/Eq was doing.  I guess if the curve is corrected +2db above 0db at a particular frequency,  raising that same freqency with the EQ will give a qumulative increase?  

PS:  Eric, I never mentioned it because I just noticed it - I prob. did it myself ;)

ekovalsky

question about Para/EQ
« Reply #5 on: 27 Jul 2005, 11:15 pm »
Quote from: tdangelo
thanks for the info guys - I kinda figured thats what the Para/Eq was doing.  I guess if the curve is corrected +2db above 0db at a particular frequency,  raising that same freqency with the EQ will give a qumulative increase?  


Yes, +2dB on your correction filter and +2dB with ParEQ at the same frequency will end up being +4dB.  With that boost I'd expect to see significant clipping unless the recording level was very low.  I'd definitely try to keep total boost under 3dB for a high Q range, below 2dB for a lower Q range.

I always hand tighten the posts, then use a wrench for another 1/4 turn.  

Tony are you still selling the RM40s or did you decide to keep them ?  My (now Aram's) RM/X were picked up today and are heading Down Under via ocean freight.

tdangelo

question about Para/EQ
« Reply #6 on: 28 Jul 2005, 12:36 am »
Eric:  I decided to keep them after all ;)  Spent a few more hrs tweaking with the RCS and placement - added the lambswool which made a HUGE difference IMO  :)  I actually replaced the tweeter binding posts with some aftermarket and am using bare wire treated with the Walkers Silver paste - that made a big difference too ;)  Next thing I'm gonna do is get the upgraded PS for the RCS.  Now I just have to sell my Maggy 2.7qr's - they were actually harder to place in my small room - I thought it would be opposite.  I'm also gonna sell the 2 Yamaha powered subs I was using with the Maggys - no need for them with the RM40's.

Thanks

Tony

suits_me

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question about Para/EQ
« Reply #7 on: 28 Jul 2005, 01:00 am »
I just skimmed, but if you have a troublesome _room_ null at 55 hz, or wherever, you can't eq it away. That's not what these things are for.

ekovalsky

question about Para/EQ
« Reply #8 on: 28 Jul 2005, 01:55 am »
Quote from: suits_me
I just skimmed, but if you have a troublesome _room_ null at 55 hz, or wherever, you can't eq it away. That's not what these things are for.


Yeah, 15dB of digital parametric EQ boost doesn't work too well :lol:

... but I can work around it by putting the 48dB/octave crossovers of my mains and subs around that frequency.  8)





suits_me

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question about Para/EQ
« Reply #9 on: 28 Aug 2005, 11:18 pm »
Oh, EQ can fix a lot of problems, but I thought my post was about attempts to EQ room nulls, a narrowly defined issue.

That cannot be done, although EQ can help tame room peaks. (And reducing the peaks often subjectively helps lessen the effect of any bass nulls.)

My post has nothing to do with factors like acoustic treatment for bass, driver response, frequency content of the recording, number of low frequency transducers in the room or using crossovers frequencies and slopes to adjust the frequency response.

If you simply try to EQ a room related null, any extra cone motion will be continue to be cancelled at the null frequency, dependent on how severe the null naturally is. That's what a room null is. There may be ways to address room nulls, but simply leaving everything as is and boosting, say, a 40 hertz band, won't do anything except add strain.

ekovalsky

question about Para/EQ
« Reply #10 on: 28 Aug 2005, 11:52 pm »
Quote from: suits_me
Oh, EQ can fix a lot of problems, but I thought my post was about attempts to EQ room nulls, a narrowly defined issue.

That cannot be done, although EQ can help tame room peaks. (And reducing the peaks often subjectively helps lessen the effect of any bass nulls.)

My post has nothing to do with factors like acoustic treatment for bass, driver response, frequency content of the recording, number of low frequency transducers in the room or using crossovers frequencies and slopes to adjust the frequency  ...


Correct, EQ boost cannot fix a room null and may in fact make it worse.  In my setup, what I did was incorporate the measured fall off around the major null at about 54hz (actually from the ceiling-floor interaction) into the crossover.  Instead of using DSP to lower output below the high pass frequency, the room does it for me.

I still measure a null at this frequency but it isn't particularly deep.