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annex666 28th December 2002 01:40 AM

Active Room Equalisation
 
Hi all,

I've been considering radically upgrading my system by introducing an active equaliser between my CD-player and amp.

The equaliser will act as a DAC for the CD-player.

Has anyone had any experience with the Behringer Ultracurve Pro 8024?

I've seen reviews of this digital equaliser and I've seen quotes that it can equalise the frequency responce of a system to +/-0.5dB *AT THE LISTENING POSITION!*

Now this is something you don't see every day and if I were to use the equaliser in the digital domain I would also cut out the added quantisation noise that would be introduced if I were to use it in its analogue role.

Sounds too good to be true - effectively I get a stand-alone DAC (upgrade from current) AND room equalisation to +/-0.5dB for only £138! (~$230).

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Are there any drawbacks?

Thanks all!


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renehuot70 28th December 2002 04:09 AM

ultra-curve
 
Hi
I've just bought a BEHRINGER dsp8024. It sound wonderfull!!!
the auto EQ mode is very good but you must finish by hear :D

in fact, my behringer sound better than my RANE ME60. More soundstage and crisp. Be aware that the behringer have a little distortion when the signal is low. If you use it in a tape loop, you don't ever notice that.

Don't forget to buy the Behringer microphone (ECM 8000)

Summary, It's the best EQ for the price

René

P.S. you can have the digital in/out option for the ultra-curve

check it at www.behringer.com

Brett 28th December 2002 04:46 AM

Re: Active Room Equalisation
 
Quote:

Originally posted by annex666
I've been considering radically upgrading my system by introducing an active equaliser between my CD-player and amp.

The equaliser will act as a DAC for the CD-player.

Has anyone had any experience with the Behringer Ultracurve Pro 8024?

The UC is OK, nothing stupendous, until you factor in the price. In an all digital systen, it might be a worthwhile addition, especially with the digital I/O as you can change to a better DAC later. The Sony SRPF300 is <i>much</i> better sounding, whether analogue of digital input, but a lot more $, and I would assume BSS units are better again.

I'm not convinced of the benefits of the UC in an analogue system. In mine it sounded dire, no matter what I did.

Look for Thorsten's review and mods of it at Enjoy the Music.com (archives) and also do a search on Thorsten (author) and 8024 (text to find) at audioasylum. There'll be tons of info there.

I only use mine as a spectrum analyser now.

NOTE: beware that the input level required for 0dBFS if you use the analogue inputs is at Pro levels, needing several volts (forget exactly, manual not to hand). Using less than full levels makes it sound very gritty.

Cheers

analog_sa 28th December 2002 06:47 AM

I was amazed Thorsten had such a device in his analogue system and liked it. Much to my relief he has finally removed it . It goes against any grain to have a minimalist valve system with such a contraption in the centre.

cheers

peter

sam9 28th December 2002 07:12 AM

I've had a 8024 in my system for a couple of months. The jury is still out. I won't make a final decision until I've installeed the current firmware upgrade. For some reason, getting Behringer to actually send it to me seems to be a problem.

On the plus side, it has successfully smoothed out athe "bump" in my mid base and added some extention. Also there was some lesser unevenness in the mid and high frequencies that are gone.

On the minus side I've noticed some strnge sounds that may indicate I've got to great a adjustment dialed in somewhere. These wewre not noticable at first, but after becoming familiar with the "new sound", I've started to notice these under some circumstances, For now I assume that they can be made to go away if I back off some of settings or I may just zero everthing out and start over more conservatively.

In sum, I would say the unit can be useful but has its limits and needes to be used cautiously.

pinkmouse 28th December 2002 12:21 PM

The UC is a good bit of kit for live sound use, but I would not use one for my home system, simply because the EQ is too peaky. Because it is designed to remove problem frequencies in a pa situation, the bands have quite a high Q, even when set on wide, and as the built in analyser detects the same frequencies, it can give a false picture of how smooth the response curve is.

As brett said, the analogue inputs are also designed for pro, 0dB, levels, so if used in this way you need to have an amp and preamp, or FX loop designed with this in mind, otherwise your gain structure is wrong and you will get more noise than if used properly.

I personally would keep saving for a while, and get a s/h BSS Omnidrive. It is a much more musical bit of kit, has greater control over the response shaping, and can also be used as a fully adjustable active crossover should you wish.

Brett 28th December 2002 01:01 PM

Quote:

Originally posted by pinkmouse
I personally would keep saving for a while, and get a s/h BSS Omnidrive. It is a much more musical bit of kit, has greater control over the response shaping, and can also be used as a fully adjustable active crossover should you wish.
Pink,
Agree with all your post, even the bit I snipped. I would love a BSS in my system, but I nearly has a seizure with what they want for them in the Antipodes. Thay's why I suggested the Sony above. Very good, and 1/3 the price (UK RRP) and 1/5 in Oz. For me though, there's still the problem of digitising my nice analogue signals, even though it brings the delays I really need in my horn system (esp the new subs). Still trying to work out how to do a DSD delay.

ThorstenL 29th December 2002 05:29 PM

Hi,

Quote:

Originally posted by analog_sa
I was amazed Thorsten had such a device in his analogue system and liked it. Much to my relief he has finally removed it .
Ahhmmm. I had the UC removed for about two weeks, I put it back. the system is MUCH better with the UC.

As for the Filters, the claim made about the high Q is not accurate. I have also had my system measured using ETF and it gave (other than suggesting a shelved down lower midrange and on which I believe is caused by the pseudo anechonic measurement methode) pretty smooth results that would not have been possible with excessively peaky filters.

Sayonara

trwh 29th December 2002 06:29 PM

Rane THX22
 
Hi

I’d like to use an equaliser in my system, I think it would represent a very cost-effective upgrade. I originally got the idea from the contributed article on Rod Elliott’s site:

<i>EQ - there you go, I have just sinned according to many a purist. I have fitted many graphic equalisers in homes, cars, and PA systems and every time, yes every time there is an improvement. This also means I know how to use the tool correctly.

I agree with my customers, silver cables do make a difference and so do pointy feet, Teflon, temperature, humidity and many other factors but the holy trinity (recorded material, speakers, room) still account for 90% of it. Sometimes more but never less!

Oh, by the way my audiophile customers who loathed the thought of EQ’ing their system now have them permanently connected, and occasionally use the bypass switch to hear what they had before (YUK). As was said on many an occasion; “Its amazing how well our brain compensates for these atrocious transistor radios”.</i>

Rane make several equalisers specifically aimed at the high end consumer who wants to compensate for room acoustics. While they are aimed primarily at HT use, I don’t see why they couldn’t be used in Hi-Fi. One model in particular, the THX22 looks very suitable - it has two independent channels each with 11 bands of 1/3 octave graphic EQ from 80 Hz to 800 Hz, and 2 bands of parametric EQ, sweepable from 1 kHz to 10 kHz. It has RCA connectors, and is designed for use at consumer signal levels. Here is a photo of it:

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<img src="http://www.rane.com/jpg/thx22.jpg" width=800 height=91>
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Here is its page on the Rane website:

http://www.rane.com/thx22.html

And check out a Rane note concerning room equalisation:

http://www.rane.com/note132.html

How do I go about setting up an equaliser for room correction? I have only ever used graphic EQs in live sound work, the units my company used included an LED in each band’s slider control which lit up when a loud signal was present at that frequency. This made ringing out a system very easy - squeals of feedback made the offending band’s LED glow brightly. For room correction, I had in mind simply recording a CD with sine waves matching the centre frequencies of the EQ bands, and using a simple SPL meter at the listening position to plot a graph of SPL vs. frequency. Then I would set up the EQ to represent the inverse of this graph, before checking the setting again with the SPL meter and test CD. Is this acceptable?

Let me know what you think,
Tim.

haldor 31st December 2002 04:44 AM

I have a few years experiance operating and setting up pro sound systems and have found that eq has only a limited effect on fixing rooms problems. About the only thing you can do with eq to help is to avoid putting energy into the dominant room modes (the resonent frequencies of the room, determined by the room dimensions length, width and height).

The reason why eq can't fix room effects is because room effects (localized nulls and peaks) are caused by reflections from the walls, ceiling and floor. The effect these reflections cause change as you move around within the room. If you flatten a room using an RTA (like the Behringer auto-tune) then the resulting eq settings are only flat for the specific location the measurement mic is located. To prove this try auto-tuning a room, copy down the eq settings then move the mic to a new location and repeat the auto-tune. The new position will have drastically different eq settings than the first. Plus you may notice that the Behringer will often have alternating eq bands at full cut and full boost, which is not a very useful way to setup an eq.

The point of using an eq is to get the smoothest, most pleasing frequency response possible from the system. The theoretical 20Hz to 20KHz flat response is not normally possible. Very few subs will provide much sound volume below 30 Hz and cranking up the eq to try and get it will just drive the amp into clipping and sound bad.

Also you need to eq a system at normal listening volume. Human hearing frequency response is non-linear and changes at different volume levels. We hear lows and highs very poorly at lower volumes. If you setup your eq for good results at 80dB then the system will sound totally different (excessive low end and high end) at 90 dB. That is why it is so important to set sound levels the same when comparing gear.

An eq can be used very effectively to smooth out the response of the speaker system, however doing this with an RTA is only possible if you can eliminate room reflections (in an anechoic chamber or outdoors). For setting up pro rigs, an FFT based system (SMAART or TEF) that provides a time windowing function is used to filter out reflections and lets you adjust the direct sound.

Phil


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