Digital EQ'ing at the PC for a 2-Channel System

falconcry72

I have always been anti-EQ in a hifi system; however, a recent thread in the Going Digital section got me thinking. I posted this thread here instead of the Going Digital section because the main point here is 2-channel sonic bliss; the digital EQ is just a *potential* means to that end.

So the basic idea is this: if you have a good DSP or EQ'ing software, you can apply equalization to music without raising the noise floor, creating distortion etc. This would allow you to make adjustments for room or speaker deficiencies without the normal sacrifices in fidelity that usually accompany a standard analog EQ, or even a stand-alone digital EQ.

Initially I was skeptical, but the more I thought about it the more excited I became at the possibility. I use foobar2000 as my media player, so I dowloaded and installed the Graphic Equalizer plugin, which is a 31 band EQ.

So far my results have been very positive. I am using it now to get better bass response out of my Magnepans. I have left all frequencies above 80hz untouched, and I have significantly boosted low frequencies in the 30hz-60hz range (6-8db's up). The result is that I have MUCH better, more even bass, and everything else sounds the same. I have been VERY critical of the high frequencies, which I do not want to be degraded AT ALL, and it sounds pretty pure to me.

If this is the case, you could theoretically use a mic and software to analyze frequency response from your speakers in your room, and then tailor a digital EQ or DSP to get ruler-flat response. Very cool... very promising.


- Naysayers: How could digital EQ'ing with your media player potentially degrade sound quality?

- Proponents: What are the best programs/tips/tricks to get the most out of digital EQ'ing with a PC?

- Skeptics: Download foobar2000 and install the Graphic Equalizer component and see what you think. They're free.

organ

edit--- Oops, misread your post. Yeah, there are benefits to using EQ's like those you mentioned. It made a huge difference in my HT rig when I let the receiver flatten the in-room response for my 5.1 set up. Haven't tried EQ for my 2ch.

SCompRacer

I tried digital EQ with my two channel system before room treatments. I believe in treat the room first as it gave me the best results, then maybe fine tune with EQ. We don't need no stinkin rules, but think about the limits of the analog gear. For instance, how much can you boost a frequency before your amp taps out and how much can you cut before you lose resolution? ~ 4dB boost was the old hard and fast rule. Not everyone has an amp/amps that has the reserves to meet the possible boost needed.

falconcry72

organ wrote: »

edit--- Oops, misread your post. Yeah, there are benefits to using EQ's like those you mentioned. It made a huge difference in my HT rig when I let the receiver flatten the in-room response for my 5.1 set up. Haven't tried EQ for my 2ch.

Yea, I generally use Audessey or the like in my HT setup, but, philosophically, I have always treated my 2-channel setup VERY differently than my HT setup. There is a certain purity, balance, and delicate nature that an EQ could never fit into... until now... possibly.

falconcry72

SCompRacer wrote: »

I tried digital EQ with my two channel system before room treatments. I believe in treat the room first as it gave me the best results, then maybe fine tune with EQ. We don't need no stinkin rules, but think about the limits of the analog gear. For instance, how much can you boost a frequency before your amp taps out and how much can you cut before you lose resolution? ~ 4dB boost was the old hard and fast rule. Not everyone has an amp/amps that has the reserves to meet the possible boost needed.

Yea, my room is pretty heavily treated with ATS panels. Maggies just interact with any room a huge amount because they're complete bipoles. In listening to test tones, I can tell they are somewhat uneven in the mid range and treble too, but it's not atrocious, so I'm not going to bother messing with it until I get a mic and some good software. What does DK use? He always has nice pretty graphs..

SCompRacer

falconcry72 wrote: »

Yea, my room is pretty heavily treated with ATS panels. Maggies just interact with any room a huge amount because they're complete bipoles. In listening to test tones, I can tell they are somewhat uneven in the mid range and treble too, but it's not atrocious, so I'm not going to bother messing with it until I get a mic and some good software. What does DK use? He always has nice pretty graphs..

Yes, I remember now that you do have acoustic treatments. My panels are dipoles while my bass modules are folded transmission line. I tend to like cutting some of that rear wave as it tends to focus my sweet spot more.

Are you using burst or continuous tones? I found continuous tend to load up and give you skewed readings. I was going to invest in that EQ software/microphone Parts Express has (~$300) but went on to other projects...Mike (Face) suggested that software to me. It does speakers or rooms IIRC.

EndersShadow

Falcon have you considered going with a miniDSP so you can bi-amp, or even tri-amp your Maggies?

It can do some of the same things as the EQ program your using I think, but I believe you can measure in room response with REW and then load and apply custom curves to the device on the fly so you can really correct your room...

Erik Tracy

I might get the digital EQ 'thang' for a system that uses digital source components in a system 'upstream' from the preamp.

But taking analog source components and then doing two conversions A/D <--EQ--> D/A just doesn't make sense...treat the room first and keep the signal chain simple. What would be the point???

And the end result is still dependent on the specific component in question.

I'd take a simple high quality rig that is analog end to end and treat the room over a cludgey digital system just to say I have digital EQ.

Not saying a system can't sound good with digital EQ - it all depends on how it is done and the specific gear being used.

edit:
But yeah - for a PC as a source.....experiment, fiddle around, and tune it, it's all about what you like.

Tbone289

My installation of foobar2000 came with the EQ DSP. I don't use it for output to my DAC and 2.1 tube rig because the components have good synergy, so I just don't need to.

However, even though I dislike tone controls, I activate the EQ DSP through the other DAC to my headphone setup (NAD C-740>Beyerdynamic DT880) to slightly drop the spike in response those cans have at 7-8Khz. It works very well in the digital realm, and I really have no qualms about it.

falconcry72

Tbone289 wrote: »

My installation of foobar2000 came with the EQ DSP. I don't use it for output to my DAC and 2.1 tube rig because the components have good synergy, so I just don't need to.

However, even though I dislike tone controls, I activate the EQ DSP through the other DAC to my headphone setup (NAD C-740>Beyerdynamic DT880) to slightly drop the spike in response those cans have at 7-8Khz. It works very well in the digital realm, and I really have no qualms about it.

The EQ that comes with foobar is not as good as the GEQ that you have to install. Here, give it a whirl:

http://www.foobar2000.org/components/view/foo_dsp_xgeq

Tbone289

The stock one works well for the very mild adjustments I'm making. What is the benefit of the add-on component?

falconcry72

Erik Tracy wrote: »

I might get the digital EQ 'thang' for a system that uses digital source components in a system 'upstream' from the preamp.

Yep, this is really about PC as source.

taking analog source components and then doing two conversions A/D <--EQ--> D/A just doesn't make sense...treat the room first and keep the signal chain simple.

I agree with you there!

I'd take a simple high quality rig that is analog end to end and treat the room over a cludgey digital system just to say I have digital EQ.

lol. Definitely not doing it to say I have digital EQ... quite the opposite... I'm somewhat embarrassed to say I'm using it!!! Hey, and I dare you to come over, have a listen for yourself, and call my system cludgey!:biggrin:

Not saying a system can't sound good with digital EQ

...but can it sound BETTER? That is the question.



With the addition of my new USB>SPDIF converter, a Stello U3, I have found that a PC can absolutely be a BETTER source component than a CD transport. Better than my ARC CD-1. This is the first time I've been able to say that my PC rig is better than a high-end CD transport, so now I'm trying to squeeze every last drop I can out of it.

Is it too good to be true?

falconcry72

Tbone289 wrote: »

The stock one works well for the very mild adjustments I'm making. What is the benefit of the add-on component?

There are more bands, which is very nice, but the main difference is that it's smoother between bands. Read this:

http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=88505

Look at this: