I’m interested in faithful audio reproduction on my home stereo, not just sheer loudness; and even if I don’t end up choosing to stay there, I’ve always wanted to start with a flat frequency response — that is, every pitch that’s played back coming out of the speakers (more to the point, reaching the listener) at the same volume.
My Sony TA-E9000ES preamp / processor has a white noise generator for calibrating the volume of the surround speakers — it sends “static” to each speaker one at a time going around the room. Because I can hear a distinct difference in the “color” of the static when it goes from my main front speakers to my center channel, I already assumed that my different speakers are not providing the same reproduction of the signal going into them — which means that at least some of them (and probably all of them) are not delivering a flat playback.
While poking around on Behringer’s web site, I came across their discontinued DSP8024 digital equalizer. It offers thirty-one 1/3-octave bands of graphic equalization from 20Hz to 20kHz — but more importantly, it offers real-time analysis of your audio system. Connect a reference microphone and turn on auto-equalization and it plays pink noise through your speakers and adjusts the EQ to give you flat response.
And because it’s discontinued, I figured a used one would be a cheap way to get into real-time analysis and flat frequency response. Within a week or so I had picked one up on eBay with the ECM8000 reference microphone.
After flattening my room response, the sound coming through my DSP8024 is simultaneously absolutely awful and absolutely glorious.
Setting It Up
Immediately upon putting the EQ inline between my preamp and amp, I noticed a significant hiss coming out of my speakers that’s never been there before. When I put the EQ into digital bypass, the hiss is still there; only when I power off the EQ to make it engage its physical bypass relays does the hiss disappear.
Wow.
Oh, and my amplifiers’ pop-suppression relays do suppress power-on / power-off pops perfectly, but the Behringer EQ manual’s statement that
Fail-safe relays have been incorporated into the design of the BEHRINGER ULTRA-CURVE PRO, which automatically and silently [emphasis mine] bypass the unit in the event of power supply disconnection or failure.
is most wildly inaccurate. DO NOT power on or off the EQ with the downstream amplifier on. Holy crap; I only did that once.
So already I wondered whether I had a bad unit, and I hadn’t even started putting music through it yet.
On to the auto-EQ.
I find the DSP8024 operating manual to be one of Behringer’s worst; it took me quite a long time to figure out how to turn on the pink noise generator at the proper signal level and get the auto-EQ function started — which you would think would be pretty simple as it’s one of the core functions of the unit.
The correct order of operations for running auto-equalization — which I’m listing from memory as it would take me literally ten minutes to find all of this scattered randomly throughout the manual even though I’ve read it clear through multiple times — is:
- Reset the entire EQ to (flat) factory defaults, including disabling the advanced functions like feedback suppression.
- Double-check that the EQ is set for flat response.
This is important because the EQ is in the output path of the pink noise generator and the auto-EQ adaptively disables frequency bands in which it doesn’t “hear” anything (if it can’t hear it, it must be outside your system’s ability to reproduce); so a band that you (or a previous owner) set low might get inadvertently suppressed.
- Connect the reference mike and select it as the real-time analysis (RTA) input source.
- Set the AUTO-Q target curve to FLAT.
The auto-EQ can generate EQ settings to make your room sound like any desired equalization curve; but why target anything other than flat? (That’s a rhetorical question, and I can think of answers that pertain to situations other than my own.)
- Put on ear protection and prepare for a physical assault (at least with my system).
- Turn on RTA pink noise generation at -20dB.
Even though the input gain is set for auto, it seemed as though running with pink noise at -48dB resulted in an EQ curve and master volume set much higher than bypass levels. Running the RTA with pink noise at -20dB gave me settings that deliver about the same overall sound volume whether the EQ was bypassed or in the loop. I know this doesn’t make sense and I’m willing to run it again to retest.
- Start the auto-EQ, watch the on-screen spectrum analysis slowly flatten out as it figures out your room, and listen to the “color” of the noise changing.
- Shut off the %^#! pink noise.
- The new equalization curve is automatically transferred to the live EQ settings.
Here’s what it got me:
Yow. Looks like I have some pretty serious room and/or woofer resonance problems in the 80Hz range, and a surprisingly jagged set of needs in the mid and upper frequency ranges.
And the Sound?
I started with Bon Jovi’s Lost Highway because it was close at hand. I had the preamp at a relatively low level, and the bass notes sounded like they were playing out a speaker with a shredded woofer — very buzzy. Wow, wow, wow.
And then I turned up the preamp to louder than normal listening volume. And I just couldn’t stop. Oh. My. Word.
Once I got up to a high enough signal level to swamp the hiss in the background and get past the low-frequency artifacting (more on this in a bit), the sound was unbelievable. I stood there with my jaw dropped switching the EQ in and out of the mix, and I couldn’t believe I’ve been listening to the way the stereo was for all these years with all that music missing. It was unbelievable.
I’ll come back to how it was good and how good it was; but first, I need to address the low-frequency artifacting. The buzzing noise does go away when the equalizer is in digital bypass and it also goes away when the EQ is active but with a flat curve, so it’s something to do with the digital equalization.
The manual warns against too great a difference between the settings of adjacent equalizer bands — that it can cause “overflow” — and obviously I have a pretty extreme difference between neighboring bands in the bass range. I tried smoothing out the lower end; but even after a fair bit of tinkering, I can’t find the point between the curve set by the auto-EQ and a flat response at which the low-end buzzing goes away.
Even if I could locate bass settings that eliminated the buzzing, they would likely be such a compromise that they’d defeat much of the purpose of having the equalizer in the first place. So chalk one up to the inability of the digital signal processing algorithm to handle extreme differences between neighboring bands.
Additionally, this EQ is made to be used with professional equipment running at a +4dBu (1.23V) signal level, not with consumer equipment at -10dBV (.316V). I’m giving it a much lower amplitude input than it’s really made for; and especially as I hear the buzzing only in low-volume portions of the music with the preamp at a low level, I can’t help but think that the DSP algorithm is impacted even more adversely when dealing with low-bit-length samples.
The buzzing does not happen when the same portion of music is played at a higher amplitude, so it’s not just a matter of higher volume in another range aurally masking the artifacting; it’s really about the input amplitude. In fact, I can turn down the digital master EQ output level, turn up the input amplitude, and largely eliminate both the hiss and the buzz at the same output amplitude.
It Sounds Awful, So I Bought Another One
That is to say, I really wanted to know whether the hiss and buzz were a design flaw or a faulty unit. So I bought another one — and when it arrived, it simply would not do auto-EQ. Whuh??? I spent about an hour reading and re-reading the manual to find out why every time I pushed the AUTO-Q button, it just came right back without doing anything.
Well it turns out, the second one was running 1.2B firmware, the first was running 1.1, and the Behringer web site has the 1.3 firmware EPROM image available for free download. Go Behringer! Rather than take the second one back to match the first, I figured I’d go forward and hope against hope that the new firmware might even address some of the DSP issues.
The firmware goes on a 27C256 EPROM, and I didn’t have any on hand (not sure why), but Joel did. He burned me a new EPROM in exchange for a burger and malt, and I was ready to swap.
Obligatory “guts” photo of the DSP8024 main board.
The new EPROM with foil tape protecting the UV erasure window.
I hot-glued the factory PROM into the case, both because I didn’t know what else to do with it and in case someone else ever owns this EQ and is weird about wanting it to be exactly the way it came from the factory (like I am with arcade games). I know the hot glue is at risk of popping off the metal case; in the long term, I may put the PROM in static foam in a baggie and tie it to something.
And the Sound?
Exactly the same as the other. The flaws are design, not damage.
How It Was Good and How Good It Was
I had described the difference in sound to Jeremy, and he and I have similar enough impressions of sound reproduction that he believed me and wanted to hear for himself.
He too was blown away.
It has to be partly the boosts in the mid and treble ranges clarifying the vocalists’ enunciation, bringing detail to the cymbals, and filling out the timbre of mid-range instruments; but it really is as though Jeremy and I had never heard the music before. Of course the correction in the bass range helps with the enjoyment as well.
I let Jeremy run the controls and I handed him CDs to try. Sometimes he’d ask which track I wanted, but most of the time he just picked the same one I had in mind. Sometimes he’d hit the bypass button to take the EQ in and out of the mix; sometimes he’d just wince and couldn’t bring himself to bypass it.
A few remarks from the session:
On “Maxine”: If it makes this sound good, it’s gotta be great! [That's the one song on The Nightfly that Jeremy doesn't love. I love them all. Favorite album ever.]
“Only Over You”: [bypass] Car driving by on the street. [EQ] Now you’re in the car. With the band.
“Foreplay” / “Long Time”: You can hear the organ growl underneath the guitars!
“Jessica”: I just want to listen to the whole album.
“Rosanna”: Wow, it even makes 80s pop music sound good. 
And many, many others.
Finally from Jeremy: I just want to sit and listen to all of my music all over again. Also: They should just label this button, “What we meant.”
Me again: On most albums, the difference is so prominent as to make the bypassed signal sound like “swimming pool speakers.” Only very, very rarely does it not make much difference — interestingly enough, specifically including much of Chicago 16.
What Next?
Because of the extra equipment to power on and the extra effort required to get a good sound out of the overall system at normal listening levels, I’m not using the EQ most of the time, so I might as well take it out of the system.
When I move the amps down to the basement, I intend to use +4dbU balanced transmission to get the signal from the preamp to the basement. It seems plausible to me that the EQ will be a lot happier with a higher input amplitude, and I’ll be happy to take the time to calibrate the output level appropriately. I’ll also build a full power sequencer for all the equipment, so I could power up the EQ and automatically wait 5-10 seconds before powering up the amps (to wait for the horrible EQ power-on pop to get over with).
I should try the auto-EQ with my speakers in a different room and/or different speakers in my family room, to see how much of the bass correction is needed because of the speakers and how much because of the room. I want to build new (triamped) speakers anyway; and if that alleviates the need for such dramatic bass correction which in turn eliminates the buzzy artifacting, I’ll be delighted.
I intended the DSP8024 as an entry-level experiment with RTA and auto-EQ, and for that it has served me well. If I’m still not satisfied with the sound in my finished system, I’m not at all opposed to buying a different EQ.
The RTA has interesting potential even where the DSP8024 is not going to be the EQ in the system. The RTA can generate pink noise, fed through a different EQ into the amps, and display the spectrum analysis of what’s received at the reference mike. It could thus be used strictly as a setup instrument to set an external EQ (graphic or parametric) for as flat a response as can be achieved with as many bands as the external EQ has available, then removed from the system.
Jeremy’s already asking about using this setup to fine-tune his car stereo — although we both have doubts about having enough and narrow enough frequency bands on an car EQ (even Jeremy’s) to get the signal as flat as the DSP8024 itself is capable of.
Don’t you think there is too much difference and lack of continuity in the auto-EQ result? The low range frequencies seem random. There could be hidden peaks between bars. Also, these abrupt differences could be the cause of the buzz. It may be bad DSP but that parameterization seems too radical to me.
Use a new room and post updates!
so what menu command did you in fact select to start generating the RTA pink noise?
my 8024 sounded terrible with a totally random eq curve set from powerup (also bought mine used) which caused the amplifier (an alto mac 2.4) to clip all the time until i realised i had to zero everything before using it
i am using balanced inputs from an old Pioneer DJM500 mixer (with CDJ500MkII cdplayers) i also have a 9024 dynamics processor/limiter/compressor but i have not learned to use either…
Great write-up. The Fail-safe relays are not for speaker protection but are so that the signal path will not be broken if the power to this unit fails. They are usually used in PA/Sound Reinforcement systems where ‘the show must go on’.
Cheers,
Andrew
Andrew, you’re right that the DSP8024′s relays aren’t advertised as being for speaker protection but for power bypass; it’s only my power amp’s relays that are for speaker protection.
I perhaps muddied the issue with my phrasing; but my point was merely that the Behringer manual specifically says that the relays will silently engage and disengage, and they were far from silent; and my amp’s manual doesn’t promise silent switching, but delivers it.
Hey Keith,
Thanks so much for posting this blog! I am really excited to try this out myself! About two months ago, a friend of mine asked me to run sound for a wedding he was playing with his band. I rented a console, and borrowed gear from everyone I knew, and somehow pulled it off. I was using my laptop with a MOTU interface to EQ my monitor sends and main outs – mostly for notching out feedback, but I did my best just using my ears to flatten out the room. I’m interested to put my ear to the test, and compare what I think is flat to what an auto-button thinks. Thanks again! rock on!
ps. Thanks for your kind words about Sparkfun – I’m the quality control and DFM guy at Sparkfun and that is how I stumbled upon your blog.
Pete, great to hear from you!
For what it’s worth, the DSP8024 has a “feedback destroyer” that purports to make a lot of noise, find the feedback frequencies, and notch filter them during your setup process, plus an active monitor that can respond to squelch feedback during a performance. I haven’t had a chance to try it yet, but I’m certainly intrigued. Just carry your best earmuffs for the setup process.
I’m planning to come back through Boulder next summer (Rocky Mountain National Park camping trip). If you haven’t got to try an auto-EQ unit by then, I’ll be happy to drop one off with you for a week.
Keith,
I’m a musician and pro-audio engineer in NH which is how I found your write-up. I just wanted to let you know how much I enoyed your write-up! Having been using this platform and process since my first version of this EQ (DSP8000 – and still in daily service) back in 1999 and can still clearly remember that feeling of audio euphoria that you described upon listening to your results of AUTO-EQ processing.
I have also recently acquired (actually from a barter for mixdown services) a DSP8024 with the 1.2b firmware (no AUTO-EQ). If you could can, can you provide a little detail regarding the 27C256 EPROM chip you had burned – was it a specific version (i.e. -c1, c2, c3, u1, u5, u6, etc)?
Having just picked up a steal-deal on an EPROM burner I’m planning to (try to) burn my own EPROM with the 1.3 firmware image.
Thanks.
Silvio, I think any 27256 will do. You can see the Toshiba chip that Joel had on hand in one of the photos about midway through the post.
Andreas, I don’t remember exactly how I caused the pink noise to generate. I know it took some time reading the manual to figure it out.
I recently picked up one of these and enjoyed your writeup.
Have the same issue with Auto EQ just returning to the RTA screen without doing anything. This is not my main problem with the unit however.
When the EQ is enabled, there is unacceptable noise through the system with or without signal. You mention this above and brush right past. Has anyone found a solution to this? Interconnects? Ground loop interference?
Justin, what I hear is definitely hiss, not ground loop hum. I don’t have a real fix for it.
My best workaround is to crank up the source’s preamp until it’s just below clipping the EQ and crank down the EQ’s master level. At least on my unit, the hiss seems to be at a constant internal amplitude, so you can fade it into the background by swamping it with your real signal at a higher amplitude and compensating with the master volume.
Since I’ve observed it on three of my own units now and you’ve heard it on yours, my guess is it’s a design flaw at a pretty deep level within the EQ.
I wonder if anyone will follow up on 5 year post. your article helped me. thanks. I know why your pinked room sounds bad. it is because you made it flat which puts too much high frequency energy in the room. there is only one eq curve that works and you will find it in the original JBl sound system design manual. They remove this little treasure bit of knowledge when they added to the manual 20 years after the first. and no one is publishing this info even though every one is selling EQ’s very few know what curve to use so things sound good. Dave
Dave, I wonder whether you had a chance to read the post in detail. The pinked room sounded AMAZING; the only things that sounded bad were the digital artifacts.
I remember you said that. I guess I was overwhelmed by length and detail. I do that myself. I remember my self thinking flat was pretty good. As sound guy, I continued to get complaints about clarity and hurting ears and often I had high frequency feedback problems that limited the usable gain I could work with. I have always been sensitive to distortion in amplified sound and today as senior citizen I know first hand the discomfort I was not aware of when I was strong and healthy. It has been said “ignorance is bliss. none the less you should know since 1990 when I discovered this curve I have never had a complaint and people praise me saying I have never heard people, even the whole choir speaking or singing with such clarity. I can hear every individual clearly. JBL uses the word “Intelligible Sound”. Bottom line a flat curve for acoustic output is not how sound works naturally. and when you force it to be flat we end up with too much high frequency energy that casus listener fatigue and pain to the ears and other problems. so down load this manual there are 2 downloads to get it all. http://www.jblpro.com/ProductAttachments/pssdm_2.pdfand turn to page 6-17 My general use interpretation of this graph is – 1 db every 1/3 octave starting at 1.2khz. this is the 1s part of the book. http://www.jblpro.com/ProductAttachments/pssdm_1.pdf I know this roll off does not make since when you first look at it but I guarantee, try it and you will be amassed all over again. best wishes.
Picked up a used DSP9024 recently,I believe both units are similar.As regards hiss and buzz in analogue mode I was able to suppress all noise by setting
gate threshold to around -80 to -85, you have to be careful here with your quite passages,a little bit of trial and error will sort this out.The next two culprits were the Ultramizer and Output gain bring both of these to around the 16db and adjust to taste.These settings were then linked to all bands.I have found that while the hiss is still there it is masked and once the passage of music has stopped the gate will keep your system hiss free.My next task is to tackle all bands individually.I agree with everything Keith has to say I am currently rediscovering all my old music collection including Nightfly.
Also used it on a live pa setup, does what it says on the tin, doubles your headroom and sits everything in the mix.
Dear friends ,
I have a problem with the Behringer ULTRA – CURVE PRO DSP8024 , in fact , two days ago on the display I received a message ” Low Battery !” I immediately changed battery and put the appropriate battery Varta 2032 3V. Time to change the batteries was about 15 seconds .
When I turn the device on , I saw that I deleted the entire memory, but I’m not much worried, but when I turned DBX M Reference Microphone, ULTRA – CURVE PRO DSP8024 would not let me make a measurement ! Please note that everything is set up according to the instructions, and so far I have not had problems with earlier measurements. Do you give me expert advice, what happened and why the device is not going to make a measurement ? What is your advice, what should I do?? Any help is appreciated !
Regards Alexander
The measurement in fact refers to automatic measurement by activating the soft key AUTO-Q !!!
Use the following steps for enabling AUTO-Q:
1. Press RTA button to access RTA mode.
2. Press the setup button.
3. Set the source to “micro” (microphone).
4. Set mic gain to +80db.
5. Set mic correction to “none”.
6. Set the auto-Q curve to “flat”.
7. Set the RTA output to “pink”.
8. Press the RTA button.
9. Press the Tools button.
10. Press the Auto Q button.
11. Press the In/Out button (pink noise will now be present).
12. Press the soft key A for the left speaker/channel reading
13. Hold the microphone about three feet back from the front of the speaker, focusing it between low and high frequency drivers. The unit will measure the frequency response of your system.
14. Press OK.
15. Press soft key A (memory).
16. Press soft key B (store).
17. Select the correct program number using the cursor buttons.
18. Press soft key A (OK.)
19. Press soft key A (Memory).
20. Press soft key C (RTA to EQ) this will send the RTA reading to the EQ.
21. Press soft key A (L) for transfer of left side measurement.
22. Press the EQ button (the corrected EQ curve will appear).
23. Press soft key D (edit).
24. Press soft key A (memory).
25. Press soft key B (store).
26. Select the correct EQ memory location with the cursor buttons.
27. Press soft key A (OK).
28. Name your EQ curve, and you are done.
29. Perform the same procedure for the right side.
30. Save.
Continues automatic measurement does not work !! Would replacing the programmed EPROM 27C256 solve the problem and whether it would DSP 8024 functioning as it should !! ??
Hi Keith.
After reading your write-up on the 8024 Ultracurve I felt inspired to find me a used one and set it up to help even out and flatten the slightly asymmetrical response of my QUAD ESL57 pair. They sit in an acoustically rather unforgiving environment and controlling them is difficult. I’m sure I’ll get somewhere with the Ultracurve, which is a nice concept, methinks. Of course I started by removing the 2032 battery momentarily so as to clear all memory and start building my filtering from scratch. The top is now back on and I’m rather optimistic about the results I will achieve. I like the 8024 even if I have only had mine a few hours yet.
Best wishes,
Roy
Amsterdam, Netherlands
P.S.: You are totally right about the quality of the manual. I usually LOVE browsing equipment reference books but the Ultracurve 8024′s is appallingly written. A bit like Mein Kampf.
Have Behringer Ultra curve pro 31 band equalizer 8024 processor that indicates low battery. How do I save manufacture preset program before replacing bad battery. Removing battery will delete al program settings. This item is now discontinued item and can’t reach the Behringer headquarters. Any info ASP will be appropriate. Thank you!
Hi Ryan ,
most information you require is in first post,
but to simplify
All manufacturers settings are stored on EPROM CHIP cannot be erased when replacing cell battery.
Only personal settings stored in memory will be lost when cell battery is removed, so these need to be saved to PC via midi section.
Hi Ryan,
to connect to PC unit needs to be EPROM version 1.3
Software can be downloaded from Behringer site if you look for DSP 9024 and hit downloads, both 9024 and 8024 use same software for PC
Thanks Raymond! All the previous comments made above only talk about operations parameter functions of the unit and not addressing any problem sues with battery failures. You have somewhat eased my mine knowing the factory setting will be there after changing out the bad battery. I am a home owner only using the Behringer 8024 in a low budget home drum studio. Little bit of drum recording and mostly listening to my favorite music. I don’t really use any personal stored settings. Just use the preset programming parameters to obtain good sound. Your comment about connecting to a PC computer & using EPROM CHIP is behind my knowledge and also do not have or access to a PC COMPUTER. Maybe I don’t have anything to worry for I dont have any personal setting to save to a coomputer but it sounds like I would have to readjust the parameter again to the way I had them set before replacing bad battery. To address to another above comment about hissing noise, in my experience when you first turn the unit on, there will be hissing noise. You can go into the parameters settings and lower the frequency tone down to about 50 Hz. Now when you return back to your 1st program page or when you 1st turn the unit on, There should be a green light above the in/out button. By pressing this button the hissing noise will be gone because you have select the signal in/out output of the unit. This method should take care of the hissing when your listening to music and you don’t have to crank up amplifier or sound levels the hissing will be massed or buried in the musics tone.
Hi Sir,
I have Behringer 8024.I need some setup help.
Ideal Pink noise level settings?
The distance between my speakers and sweet spot is 5,5 m.
Line gain?
Mic gain?
My speakers are tannoy15 golds,amplifier is Jadis ja 30.
Analyzer peak or rms?
I don’t want hurt my system.!
Regards
Hi,
MR.Javanovic’s instructions were very helpful, thank You Sir.🙏
Some friends are saying put the microphone to your listening point and make an other measurement ?should I?
And my levels after the rta analyze were one channel too high one channel too low.may be the Level settings are somehow wrong.Any more instuctions,
Javanovic please help needed..
Otherwise after the RTA measurements the sound became very dynamic and balanced in every manner.
But I put the EQ results in to my Analog 31 band equalizer Clark Teknik dn370..
I am very satisfied with this set up..
Does anyone have the DSP8024 firmware, so i can re program my eprom chip?
Ryan,
I can’t find the software to update the Firmware to 1.3. Do you still have it? If so, can you email it to me with instructions?
Thanks,
Barry
Hi.
Im looking for the ultra curve design software for remote controlling a dsp8024.
Im running winxp.
does anyone have it?
it is not at behringer website anymore.
thank you.
leyenda3@hotmaol.com
Hi, can any one help me with a 8024 question?
If I change something under EQ, I hear the difference. If I want to see what those changes do visually to the output, pressing RTA button, it shows the graph, but also disables the EQ settings. In other words the changes I made under EQ, can not be heard once I switch to RTA. So I can only use the EQ change if I press EQ. I expected also to see the changes in the graphical output of the signal. Am I doing something wrong? Or is this not possible?
I have firmware 1.2.
Thank you in advance,
Martin
Hi all!
The 1.3 firmware and the ultra curve design software for remote controlling can be found Behringers site under the DSP9024. It seems to use same firmwares than 8024.
Kim