7 ch eq

[chambers1517]

I have 2 khorns and 3 lascalas. I also have 2 klipsch subs. I ran a frequency cd and noticed I have a bad spike around 35 hz. My room isnt very smooth overall. I was considering a 7 ch eq. It is an Audiosource Bijou. Anyone ever tried to smooth out a room with an eq?

[IndyKlipschFan]

7 channels is not enough.

I would suggest a very good stereo 31 band eq at a minimum.

With out offending you, think of these as tone controls like bass or treble. You can turn up or down each of the 31 steps from the lowest tones to the highest ones in steps.

If your finding a spike or loss at some part of your system this EQ can smooth it out.

Last, pay good money for a good EQ. Otherwise, your going to add a LOT of noise into your system. Or learn to live without one. DBX has some pro modles that are very very good.

I use this one for a Karaoke system with La Scalas... And I am very happy with it. DBX 2231 You can read about it here.

http://www.musiciansfriend.com/srs7/search/detail/base_pid/183506?src=3WBZ4DS

Hope this helps.

[sfogg]

If you are trying to deal with room effects on your subwoofer forget about graphic EQs all together. Even 1/3 octave units aren't precise enough to deal wtih room probably accurantely. What you need is a parametric EQ. A popular unit for sub only duty is the Behringer Feedback Destroyer (BFD). These go for around $150 and offer 12 filters per channel for two independant channels.

Shawn

[IndyKlipschFan]

sfogg..

He said his room was not very good overall, and also a problem with his sub area. While I agree most graphis EQ's are trash, this one is not.

I stand by my recommendation.

Have you played with, or used the DBX unit I mentioned? I have.

[colterphoto1]

Indy, I think he meant 7 channels as in enough channels for each HT speaker. Your 31 is generally referred to as the bands of EQ. 31 is roughly 1/3 octave per 'slider'. Including the slope of the Eq, each 'band' would probably be audibly affecting 1- 1/2 octaves if it's 6 dB or 12dB per octave slope. Your illustration of bass and treble is quite correct, and they are VERY wide acting controls.

A parametric EQ, such as is contained in many PA units or the Yamaha line of receivers with the calibrated mic (probably other top brands as well), controls not only the LEVEL of boost/cut per band, but allows the user(or computer setup program) to determine exactly which FREQUENCY is the center point of the band, AND adjust the WIDTH of the band to obtain the flattest frequency response. This is very useful in PA when when taming a feedback situation and might be a solution for you. However, running all your signals through an additional processing device would most likely cause some degredation of sound and unless you have test equipment, will allow the user to make judgement errors in the settings.

I would suggest trying to tame the offending frequency by the use of speaker placement and room modification. You might post your room dimensions, equipment and speaker layout on the Architectural Forum here. Artto is our resident acoustician (am I just making up words now?) and is usually willing to give pointers to correct your situation.

Good listening

Michael

[sfogg]

The problem I pointed out wasn't based on implementation, it was based on the precision of a 1/3 octave EQ. I haven't used that DBX unit but I have owned 1/3 octave 31band constant Q Audio Control C131s which are also highly regarded. And like I said it isn't precise enough to handle room problems.

They don't have enough resolution to deal with room resonances... you need on the order of 1 hz resolution to deal with a resonance without screwing anything else up... a 1/3 octave EQ isn't even close to that precise. In the first octave each band covers about 6hz.... in the next band it is closer to 13hz per slider, the octave about that it is 26hz per band. After I bought the parametric EQ I ended up selling the C131s which cost nearly 10x what I bought the BFD for.

Have you ever used parametric EQs and/or measurement tools that offer more precision then 1/3 octave? Things like True Audio Level 4 or ETF for example?

Shawn

[IndyKlipschFan]

Colts Win.. OK, off topic.. Whew..

I took it as a sub eq. Berigner, in general, is very mid to low mid gear. Some call it trash below "Peavey mid gear" and most units of stuff they have made I would tend to agree. I have never seen thier stuff in any high end studio and usually well established bands I have heard live with good PA's do not usually have the Beringer gear in use too.

Contrast that with DBX, names like Lexicon, and what you get.. is what you pay for.

And feedback controlers...again for live sound where can I get rid of that hum. If he is getting real feedback hum in a home situation he really does have some serious problems..LOL (hidden mic left on or ghost singer in the back corner?) You get my point.

[IndyKlipschFan]

Shawn I have in the studio setting yes.. And they are as you described. Also at a cost factor too. I am sure a very high end Parametric is above his cost/ use too.

Were all trying to help him. But adding noisey mid level gear does not help his situation.

I think the DBX has constant Q too.

[sfogg]

"Contrast that with DBX, names like Lexicon, and what you get.. is what you pay for. "

Have you ever used one? Have you ever spent time on any serious subwoofer forums? The BFD is *extremely* popular on those forums.

I have used the BFD with my Lexicon MC-12B for my L/R subs up until Lexicon incorporated their own Room EQ into the unit. For sub duty it is a very good unit and is far more useful then a 1/3 octave.

"And feedback controlers...again for live sound where can I get rid of that hum.  If he is getting real feedback hum in a home situation he really does have some serious problems..LOL (hidden mic left on or ghost singer in the back corner?)"

The way feedback controllers work is by assigning a parametric EQ filter on the frequency that is causing the feedback and cutting it way down. If you had any experience with the BFD you would also know that in addition to automatically doing the above function the user can turn that off and use it as a conventional 12 band per channel stereo parametric EQ.

Shawn

[IndyKlipschFan]

Yes, I/we have used one in live situations.. like this?

The Beringher DSP1124P locates feedback frequencies immediately and sets extremely narrow notch filters to destroy them, leaving the remainder of the signal virtually untouched. With its various modes you can master just about any live sound situation or use it as a creative sound-shaping tool with 24 bands of fully parametric equalization. Now with 24-bit A/D and D/A converters. So yes for low sub feedback harmonic distortion problems..

Look at the http://www.dbxpro.com/2231.htm

Is a great overall sound soulution. Not trying to fight with you Shawn. Trying to figure out what the original post was trying to convey. You read it as a sub only problem, I saw it as a full spectrum not great, and a sub problem too.

Two different approaches, especially for home use.

I, again, thought he was stating his own room overall was not good. This would be a great piece if ONLY the bottom end was a problem. And like I said, a 7 channel eq would not be enough.

[sfogg]

"You read it as a sub only problem, I saw it as a full spectrum not great, and a sub problem too."

But even if you want to do both the DBX box isn't going to work. He is obviously using some type of surround processor so the subwoofer signal is seperate from the L/R signal. So you could use the DBX on the L/Rs or the sub... but not both.

On the subs the DBX will offer about 7 sliders that will do anything... and they most likely won't be on the frequencies needed and they will be to wide.

" And like I said, a 7 channel eq would not be enough."

You are mistaking 7 channel EQ for 7 band EQ. It isn't even remotely the same thing. The DBX is a 2 channel EQ. Do a search on the Audio Control Bijou... it would fit his needs better then the DBX box you are suggesting would and it offers greater precision for the subwoofer channel then that DBX box does.

But to really deal with problems in the bass (and the original poster specifically mentioned problems at 35hz) he is going to need parametric EQs to attack the rooms influence with enough precision.

Shawn

[IndyKlipschFan]

DP

[IndyKlipschFan]

So a seven band eq (per channel), like I said would not be enough. Again if it is just the Bass he is having trouble with your suggestion is a good one.

I did happen to look at this unit. Actually pretty good. (Very cool if you had older speakers needing some spicing up.. Like say older Altecs. Maybe not be "politically audio correct" but they will sound better!) A five channel 7 band EQ. Each channel has separate EQ.

http://www.hificoncepts.com/hificoncepts/audconbij.html

THX® Home Theater Equalizer

7 Channels

Easy to set graphic equalization control

Stereo subwoofer equalization

Constant-Q topology for precise control

Digital 5.1 ready

THX® DB-25 connectors

Made in the USA

But again, not enough of the full range needed, we both agree on.

If your problem is only of sub solutions your suggestion is a good one.

[Griffinator]

Guys, no EQ is going to solve a major standing wave like that. On the contrary, it will create unnecessary distortion in the signal.

What he needs is some good bass traps.

[chambers1517]

Thanks for the help guys. I will explain in a little more detail. The khorns start to roll off at around 100hz. The spike at 35hz is actually more like a hill. It rolls off gradually to below 20hz. Above 35 hz it rolls off to about 100hz then begins to come back up and flatten out. The sub follows this same curve despite placement as well as the khorns. This is why I thought I might need a 7 channel eq. I could raise the mains as well as the sub to get a smooth response

[Griffinator]

I reiterate. Don't use an EQ to fight off a standing wave. It never works.

Get some bass traps into that room. That's the most sure solution to the problem.

[Colin]

In my previous limited experience, I found that an old graphic Audio Control EQ worked best if you apply a lot less medicine than the doctor recommends.

If a 6dB boost was required, for example, then a mere three dB bump actually eased the problem and balanced the rest of the frequency spectrum better than applying the full measure. Sliding each of the frequencies to the full amount, required to balance the overall response, only made other frequencies worse. The sound got slow and muddied; other frequencies went out of whack. Too much 20Hz bass, for example, overpowered the mid-bass and slopped over into the mid-range. The main thing is to flatten the peaks softly and fill-in the valleys gently. Even so, the $30 price I paid for the unit at eBay made my original Klipsch horns sing like Pavarotti. Today, surrounded RealTrap panels, my current big ole horns negate the obvious need for equalization.

Many speakers and amps combinations cannot handle the power needed for a fully equalized flat response down to the extreme bass levels. They simply cant push enough energy into a specific low frequency without messing up the frequencies nearby. EQ doesnt modify serious room anomalies, like major nodes or nulls. It cant make a bad room sound great, but it can make a good stereo sound better much better. That is why EQ is like icing on the cake. It should come after serious acoustic room treatments, like RealTraps.

[J.4knee]

Griff has the best advice. Fix the room first then take another look to see what your repsonse curve looks like. Bass traps for your current problem should be your first move.

[dodger]

With his explanation of what is happening, the problem sounds to be a standing wave (s).

Bass traps and some experimentation in speaker placement should correct that.

[Griffinator]

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On 12/13/2004 12:55:21 PM dodger wrote:

With his explanation of what is happening, the problem sounds to be a standing wave (s).

Bass traps and some experimentation in speaker placement should correct that.

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Which is what I've been saying...