Equalizers in your system?

[Coytee]

Over on AK, someone was asking about "what happened to equalizer". There were various comments about them and I finally chipped in and said

I've not read all this yet but I'll toss a thought out there.

I've always owned an equalizer. I have had since 1980 or so, an Audio Control C-101 and though I still have it, I also now have a dbx 14/10.

Both are currently removed from my system but I've had them in/out. All that so no one thinks I'm bashing eq's, since I own two.

Ok... My understanding is, you can't REALLY use an eq to "fix" a room. Yes, you can contort the sound.

I've got a 90 hz standing wave issue in my room. I happen to have a slider right at 90hz so I can notch it down a couple db's and I have to admit, much of the muddiness is gone.

I was talking to a guy who has forgotten more about this in the last 10 blinks of his eyes, then I've ever known. He told me that was erroneous thinking on my part. He said when I notch it down several db's at 90 hz, what I'm doing is cutting out original material and the room won't compensate for that.

He didn't argue that it might take some mud out of the room but it's ALSO removing the sound and will not be replaced.

He uses phrases "non-minimum phase" and things like that. Frankly, it's a bit over my head so I put it back to him in my words. This was a question to him, in the form of a statement.

"you can eq the sound as long as you are doing the eq'ing BEFORE the mixing board. Once it goes past the mixing board then you have the final mix and any eq'ing done at this stage alters the intended sound.... furthermore, if you have a need to eq (like I feel I do in my case), you should look into fixing the ROOM before trying to apply a bandaid with an equalizer"

he said that more or less... I finally got it.

So, with all respect, I bring that to you and let you digest it as it may. For me to hear HIM expain it, it's all clear as day....once he leaves.... I coudln't repeat 10% of what he just told me and have it make sense!

Someone else then added: I agree that fixing the room should be first, but if you EQ for a flat response using an RTA & pink noise, isn't that independent of any recording?

To which Fred Sanford responded with:

I think what he was getting at is that time is part of the equation. What you're seeing as flat can be a certain percentage of new signal ('now') from your speakers plus some room reflections ('then') of what played previously. You adjust your EQ so that, with pink noise, the speakers + these reflections = flat. You're likely reducing the 'now' so that 'now' + 'then' = flat.

When he's notching it down at 90Hz, he's reducing the buildup of 90Hz reflections in his room, but he's also changing the ratio of music ('now') he's listening to in relation to reflections ('then'). In dynamic music, the frequency spikes are often transient, and don't build in the same way that constant pink noise does. However, he's pre-emptively reduced certain frequency bands in anticipation, effectively altering the balance of the overall sound just in case.

This is one of the battles you face with live sound reinforcement in a reverberant space (especially when the surroundings change throughout the night with varying population density & temperature & humidity).

I just wanted to say that this explination by Fred was what I was trying to say my comprehension was. He did a much better job describing it than I could have (out of my simple ignorance). I thought I'd copy these snippets here so anyone with an equalizer could contemplate the logic of using said eq, to try to fix room issues as I had done.

[mark1101]

Good post Richard. Makes sense to me. I have always used an EQ too. Now, I use room treatments, plus an RTA system, plus the EQ. It doesn't fix things 100% but the carefully chosen room treatments provide some absorption in selected frequency ranges and the EQ helps balance the sound. As you know our speakers require the use of EQ. So there is really no way around it. But I agree the EQ won't fix the room.

[Groomlakearea51]

Very well put Coytee and Mark. I spent alot of time on the design and lengthy discussions with MAS (where is he by the way...?) when I designed the "man cave". "Flat" (no EQ) sounds very good, no standing waves, etc. Being a "tweaker" and doing some final listening, I inserted a SAE 2800 PE into the "equation" (in between the decks and the amps).... After fiddle-fartin around with it for about 2-3 weeks, the final "arrangement" was ~+1-2 dB at 80 hz, 320 hz, 1.9 khz, and 5 khz, with the bandwith "notch" at 3.5 octaves wide. Very little really, but just made the difference I was looking for. Actually, the most useful tool on the 2800 are the line attenuators that allows me to do really fine tuning on the overall gain before the source signal hits the amps (I can now keep all recordings I'm listening to at the same volumes without fiddling around with the different amps' volume controls). They have uses, to be sure.

[Don Richard]

Modern DSP-based eqs can independently adjust amplitude and phase. Finite Impulse Response is the technique used to accomplish that. Look for FIR filters in the specs if you need minimum phase shift equalization. I just got an email from Crown indicating that their Itech series amps have FIR filters controllable through System Architect 9.0.

[SWL]

I've always favored slight cuts rather than boosts with and eq. Tone controls have also been a long time friend of mine. When a system is run flat.....that's exactly how it sounds to me...FLAT. I like to tweak it a little......just a little.

Now I enjoy room treatments in addition to eq and an active crossover. []

[mikebse2a3]

I've got a 90 hz standing wave issue in my room. I happen to have a slider right at 90hz so I can notch it down a couple db's and I have to admit, much of the muddiness is gone.

Not only was the muddiness gone but the tonal balance and clarity was improved throughout the room IMO and I believe you noticed that also from your comment to me Richard. This is very strong proof that the EQ was a genuine improvement. Of course you can use bass traps and specificaly tuned treatments for this problem if you are open to the room's cosmetics being changed but that probably isn't an option in your situation. So you can trust your ears and use the EQ or continue to listen to the muddiness because some say it can't do what you clearly are able to hear it accomplish. I would also like to add that Richard had also just installed some very expensive extreme slope crossovers and the improvements we both heard and commented on was the EQ offered a very obvious improvement while the crossover change was considered very mild in comparison.

Unfortunately Equalizers and their application have been misapplied and abused and thus have received a very bad reputation. The fact is though when implemented properly they can and do offer real world improvements to a system/room.

I would never argue with the fact that room treatment should be the first option chosen when available, practical and acceptable in any given situation. Of course nulls and also room reflections cannot be corrected with EQs(unless they can compensate for time due to the non minimum phase conditions and then generally will only be somewhat effective at a limited listening area).

There are some good research papers that I have read in the past that do indicate that under some limited conditions that EQ when used properly can address an issue like Richard has. From what I have read and experienced myself the conditions necessary for this EQing to be beneficial involves frequencies wavelengths that are close to or larger than the room's dimensions which also allows the EQ correction to be within an acceptable time window in relation to the orginal signal) We are talking in acoustically small rooms and generally under approximately 160Hz. The problem area needs to be measured/identified and will usually require a PEQ filter with Q adjustment so that only the area of excess gain is altered. If done properly the result will be a restored tonal balance and improvement in clarity due to the former problem frequency band energy dying away much sooner(This can also be observed in a waterfall plot of the EQ'd region) as it would have if the room itself(which is acting as a Equalizer itself) had not introduced excess gain in the problem area.

I would also like to comment on one more area that an EQ can help with a very obvious problem. That is with our recorded material that we want to listen to. I like many have in the past thought that the recording was sacred and no manipulation should be used as far as it was concerned. Well my experience is that yes we have some very well done recordings that no EQ need be applied but many recordings will benefit from a well designed EQ with filters designed and used with restraint for just such a purpose of restoring tonal balance to recordings (one example of a EQ developed for such a purpose was the Cello Palette by a company by Mark Levinson). The reason why many recordings sound bad tonely when reproduced by our systems are many but some like the recording enviroment, monitoring enviroment/loudspeaker being used to decide the tonal balance are variables that IMO a proper EQ device can offer to us a valuable tool for improvement possibilities for such recordings.

Link to were I have adapted a Behringer DEQ2496 PEQ filters to simulate the Cello Palette and links about the Cello Palette for anyone interested. The EQ very importantly is easy to use while listening to a recording for the best sound (somewhat like tone controls) and can be easily bypassed when not needed for the best recordings.

http://forums.klipsch.com/forums/t/112125.aspx

mike tn

[JJkizak]

Since adjusting the room acoustics is forbidden I adjust my equalizer, bass, treble, loudness, expander/compander to what I like to hear, not what is correct. My hearing range is 19hz to 12.5khz and not 1 hz more. But my SPL meter hears much better than I.

JJK

[Hifi jim]

I've never owned an EQ, but I did use tone controls and loudness for low level listening often. I've since owned a Pioneer receiver which featured their room correction system and I thought it worked well correcting room acoustics. I recently replaced the Pioneer with a Yamaha RX-v1800 which uses their YPAO room eq and I think it is even better than the system Pioneer uses. With YPAO engaged, dialogue is far cleaner than I've ever experienced and music is very balanced and cohesive. At first, I had my reservations but after leaving the eq on for two weeks and then switching back I realized how effective YPAO is for me. I've never thought that equalization was an effective tool for audiophiles but after experiencing what room eq can do I am doubtful I will ever be without it, especially for home theater. Two thumbs up here... [Y] [Y] []