[drphoto]

When I first got into 'hi-end' audio (meaning discovering the world beyond Pioneer) waayy back in the 80's, I was told that no respectable preamp would have tone controls and no system would have.....gasp.....a graphic equalizer!

Why? Well, the dogma was tone controls induced phase shifting which ruined sound staging, and all that extra circuitry added noise and distortion.

Well, what about digital EQ? Aren't you just messing w/ data? Why should that have the same problems?

As someone who does live sound mixing on the side, I know the value of EQ and tone controls. My band occasionally plays a room w/ a nasty resonance at 100 hz. Once I figured this out, and put in a notch, we could still have that punchy bass people expect from a live rock band.

I digress a bit, but it seems like it would be equally desirable to deal w/ home room issues. I've learned how much the room is a factor over the past few years.

I'm gonna demo a new DAC this week, but tonight I saw a review by JLM on a relatively cheap mod to the already inexpensive Behringer 2496 (sp?) which also does the A to D conversion. (as far as I can tell)

If this works....why isn't everyone doing it?? Why are there not a plethora of digital EQ units on the market? I know there a a few expensive one's like the TACT, but it seems like more would follow.

Must be a catch somewhere.

[srb]

While this thread is finding its proper home, I haven't seen much of anything in the middle, between the inexpensive Behringer and the expensive TACT.
 
Obviously, the HT crowd is doing room correction with the digital EQ in their HT receivers.  The stereo purists are a little reluctant to put an inexpensive digital EQ in the path, particularly if they are feeding it analog and need to do an AD/DA conversion.  I know there are number of people who perform Behringer mods, but usually not inexpensively.  (I missed the JLM post on the inexpensive mods.)
 
For those of us who are starting with a digital source, I agree there should be a market for something in the middle price range.  Maybe one of the smaller progressive companies like NuForce, Peachtree or Virtue Audio might want to take on a project like that?
 
Steve

[JimJ]

I use an analog EQ...so there

[JLM]

Yes, I'm using the Behringer DEQ2496 as both a DAC and DEQ.  The mods Scott Endler did only relates to the DAC function.  The design of my single driver speakers (Bob Brines) included a baffle step/zobel circuit to improve performance, so the biggest purpose of the DEQ was to eliminate that circuit and allow for the most direct possible connection between my monoblocks and the drivers.

Although I'm a purist and already had a nearly ideal setup before (room dimensions/nearfield listening ala Cardas, absorption panels at first reflection points, dedicated circuits/grounding, insulated walls/door, etc.) the DEQ made a huge difference.  Functioning purely in the digital realm I had no qualms about adding the Behringer.  Overall the sound "makes sense" with a much flatter frequency response.  But the frequency extensions (already quite good with the Fostex F200A drivers) is amazing.  The somewhat "soft" highs are now fully on board.  And I now have lots of deep/tight/clean bass (that was incredible before compared to other single driver designs and better now than my Hsu VTF-2 sub in my A/V system). 

EQ users swear that once you've used it, you'll never go back and I now agree.

BTW moving up from using the Oppo (Stereophile Class C) as a CDP to a transport only with the modded Behringer DEQ2496 DAC function was also a very enjoyable step (or two) up.

[drphoto]

Well now I'm more unsure on what to do than ever. The Endler mod is affordable, even if  one had to buy the Behringer unit new. I would agree that it makes no sense to convert digital to analog, only to convert it back to do DEQ.

I'm assuming the EQ is done before the data stream undergoes the digital to analog conversion. Or am I mistaken about this?

It just seems to me that room correction could be of enormous benefit regardless of the speaker modality employed. As long as it doesn't introduce it's own set of problems, of course.

For JimJ. I guess you like your analog EQ and don't find it causes the problems that the dogma dictate? Mind if I ask what you are using?

[Wayner]

Most people find that the room is the problem rather then the electronics, so their strategy is to fix the room rather then fuck up a nice flat frequency response out of the electronics. I've owned 2 very fine graphics, one by JVC and one by Soundcraftsmen. It just makes more of a mess then it fixes, IMHO.

Wayner 

[Brandon85]

Pre-amp tone controls are rightlfully condemned for being both being too coarse to control music frequency properly and being completely uncalibrated.  The latter weakness also applies to analog EQ.  Pink noise competerized calibration and DEQ finally solved this last issue and reached it's height in the early 1990's.  But then MP3's, music compression, and music portability almost completely decimated the audiophile stereo business.  These days it seems no manufacturer even dares to re-enter the high-end EQ market for perceived lack of demand.

That being said, the value of DEQ in normalizing an uneven listening environment is undisputed.  Purists, especially who likely never tried a high-end DEQ like the ADC SS-525X recently posted in the trading circle, simply don't know what they are missing.  An A/B test would of course quickly convince them... but then again I'm also sure some of them prefer the "colored" music their ears have become accustomed to (regardles of its lack of frequency accuracy).  To each his own.  I know I definitely like my music to be unaffected by the various frequency shifts each of our components, speakers, room, and furniture inevitably interject into the playback before the music hits my ears.

[Wayner]

There is nothing wrong with preamp tone controls if they are designed properly and aren't gross about their changes. The graphic equalizer is nothing more then a series of tone controls thru the audio spectrum. The skill or necessary calibration equipment required in addition to the EQ turn into a cost that has diminishing returns. Your better off treating your room or becoming an engineer and make the records sound the way you want.

Wayner aa

[Brandon85]

Most pre-amp tone controls I've seen, even fancy parametric tone controls that allowed you to vary the width of the frequency band being modulated, are unfortunately what most of us would consider to be far too limited to be useful because they can still only impact at most one or two frequency bands.  That's why it's considered good audio advice to buy a pre-amp that has no tone controls or ones that can be bypassed.

Incidentally, Wayner, you don't need either extra calibration equipment or any user skill at all with a DEQ like the ADC SS-525X.  It comes with a calibrated mic, generates its own pink noise signal, and has the computer onboard to analyze the frequency response.

I totally agree that treating your room with material friendly to acoustics is beneficial... however, that alone will never gaurantee frequency accuracy in playback.

[Wayner]

A properly treated room will not require EQ.

W

[Brandon85]

Waynor, are you really implying that your and my stereo would sound exactly alike if both were installed in the same properly treated room?  Too bad we're not in the same area to have a beer and quickly disprove that theory! 

The only point I am trying to make here is that even if you isolate it only to the music playback loop it is clear every component (source, pre-amp, amp, interconnects, cables, and speakers) interjects some degree of coloration on music.  Sure, one could try to correct that with room treatments but how practical or objective would that really be?  Probably "not very" on either count which is the crux of the problem.  Ultimately most of us living in the real world have multi-purpose rooms at home that we can't dedicate soley to the stereo.  A good DEQ would solve this for drphoto.  It would surely work just as well at his home as it does in live sound mixing at a club IMHO.

[srb]

The ADC SS-525X performs EQ in the analog domain.  It is digitally controlled, in that it uses "digital sliders" instead of noisier analog slider potentiometers, and it can store the adjustments in memory.
 
Unlike the Behringer DEQ2496, it does not have a digital input or output, and does not use AD and DA conversion to perform EQ in the digital domain.
 
AFAIK.
 
Steve

[Wayner]

No, I have AVA electronics, a fast array of speakers and several rooms filled with other odds and ends. Unless you have my exact set-up, they will never sound the same.

Wayner 

[Brandon85]

SRB... correct, the SS-525X works in the analog domain and doesn't do an AD/DA conversion but right off the cuff I can't think of a good reason how an EQ would benefit from working in a digital frequency correction mode versus analog.  I guess if someone made a digital processor that was able to control many more bands at much finer resolution than 12 independent bands in +/- 2db steps such an EQ could technically claim greater accuracy.  Whether or not this would make a meaningful difference or not only real world A/B testing would show.

As a general rule though one should avoid digital manipulation completely and remain in analog whenever possible (can you tell I  own vinyl and a turntable?  ).  As for CD's one DA conversion is bad enough for music quality so putting music through an additional AD/DA conversion just for EQ obviously invites all sorts of digital error introduction (quantization, jitter, etc.)

Wayner... you're in luck, I don't have your setup so you're safe, haha. 

[srb]

As a general rule though one should avoid digital manipulation completely and remain in analog whenever possible (can you tell I  own vinyl and a turntable?  ).  As for CD's one DA conversion is bad enough for music quality so putting music through an additional AD/DA conversion just for EQ obviously invites all sorts of digital error introduction (quantization, jitter, etc.)

Analog EQ filters usually induce phase deviations and add noise distortion.  But I would agree with you, if you are feeding an analog signal from a turntable, you would probably not want to subject that sweet analog signal to additional AD/DA conversion.
 
But from a CD player or music server, feeding a digital signal into a unit similar to the Behringer DEQ2496, which would perform EQ and then DA with its internal DAC, would be the better way to go.
 
As I stated before, I would like to see an amazing sounding unit less expensive than the TACT and more expensive than the Behringer, that is ready-to-go without modification and doesn't have the asthetic of cheap DJ equipment.
 
Steve

[JimJ]

For JimJ. I guess you like your analog EQ and don't find it causes the problems that the dogma dictate? Mind if I ask what you are using?

Actually, I'm using a pretty crappy EQ now, just a DBX 15-band/ch graphic, until I can afford the Rane I'm looking at I've heard setups with absolutely no EQ in treated rooms that I like, and on the other side of things, I've heard setups in cars (pretty much the worst acoustic environment) that have dual 1/3-octave EQs that sound great. I'm not opposed to it, as long as there are no noise issues.

[Brandon85]

But from a CD player or music server, feeding a digital signal into a unit similar to the Behringer DEQ2496, which would perform EQ and then DA with its internal DAC, would be the better way to go.

Agreed.  If the Digital EQ has digital inputs like the DEQ2496 then you sidestep an uneeded AD/DA conversion.  However, you might not prefer the DAC of your EQ if you have a better outboard DAC in your system.  Wonder if the DEQ2496 can output digital signal to another DAC?  In any case, based on its rough studio rack design I wouldn't personally consider using it as an EQ in a home stereo.

SRB... so are you really using an HTPC as a music server for digital wav playback?  How's that workin for you?  I'm a PC too but wouldn't use a computer as a music server, it's just too noisy electrically and mechanically for me to ever consider it audiophile grade.  But speaking of product wishlists... I'd certainly like to see Apple or somebody who is iTunes compliant make an audiophile grade music server where the hard drive circuitry is electrically isolated from the onboard high-end audio stage.

[srb]

Wonder if the DEQ2496 can output digital signal to another DAC?  In any case, based on its rough studio rack design I wouldn't personally consider using it as an EQ in a home stereo.

There is an optical S/PDIF output and an AES/EBU output that could be fed to an external DAC.  Of course the jitter added by going in and out of this device is a hot topic in itself!  I agree on the studio rack design, and wonder what the Behringer product would be like if offered as a $600 audiophile edition (ESS Sabre 32 DAC, audiophile caps, BNCs, upgraded PSU!), instead of the $300 industrial box it is now.
 

SRB... so are you really using an HTPC as a music server for digital wav playback?  How's that workin for you?  I'm a PC too but wouldn't use a computer as a music server, it's just too noisy electrically and mechanically for me to ever consider it audiophile grade.

Yes, I am using an HTPC and iTunes.  Currently, I am DAC-less, but I was taking a coaxial S/PDIF out from my motherboard into a Stello DA100 Signature DAC, which to me sounded better than out of my midrange Denon CD player into the same DAC.
 
The PC sits in my rack in a sexy black brushed aluminum OrigenAE HTPC case, with passive processor and video cooling, Corsair PSU w/ 120mm fan and Noctua low-noise, low-speed 80mm case fans.  The OS drive is a quiet single-platter WD, and the data drives are Samsung low-noise F1s.  It is not totally silent, but fairly quiet - I can barely discern its running from my seating position if no sound is output through the speakers and everything else in the room is off.
 
I also use the PC with Vista Media Center and am able to record 4 shows at once (2 - SD and 2 HD) and can simultaneously play music from iTunes without skipping a beat!
 
I'm sure I could improve on the sound, and like most audio nutcases am thinking and plotting a better sounding setup, but for now, it actually sounds pretty good, even in the face of the all the theoretical PC interference.
 
Steve

[JLM]

Except for questionable build quality and XLR connections, the Behringer does everything you guys are asking for: +/- 15 dB in 1 dB steps, pink noise generator, a mike is available from Behringer specifically for the DEQ, 31 bands, RTA, up to 10 different simutaneous parametric settings are possible, and its all done in the digital domain.

Yes, in my application the digital output from my CDP is fed into the Behringer, so there's no extra ADC or DAC.  Drphoto, I believe that if you input/output digital, only the EQ circuits are used (not the DAC which frankly appears to have been just an after thought feature in the stock unit).  Again, in my application the primary EQ function was to replace baffle step/zobel circuits as my listening room/setup should already have been quite good.  I was blown away by how much improvement EQ provided to what theoretically should have been pure/nearly ideal situation.

Add EQ to my short list of audio epiphanies.

[macrojack]

Where does the dbx Drive Rack PA fit in this discussion? I use one in an actively bi-amped system with very good results. It provides graphic EQ, parametric EQ, three way crossover, limiter, feedback suppression and pink noise generator. I bought the matched dbx calibration mic which can be used in conjunction with the built in real time analyzer. This whole thing works very well in matching my large horns with 15 inch woofers in an actively bi-amped arrangement. Perhaps the Drive Rack PA is what you are looking for. The unit with mic cost me about $510 shipped from Amazon.

My only quibble is the faint rushing sound that can be detected when everything is muted. A local sound engineer told me it was due to the extreme high efficiency of my horns.
Most people would not have that problem.