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Digital Signal Processor to tune your room


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"Do these work?"

Yes, and no.

They can make your room measure better, by pulling down peaks, but they can't fill in nulls. Another thing being the correction is for one mic position only.

The no part is that although you can make it measure better, it does't always sound better. Different sounding, yes, but better? Not always.

If your speakers have an amplitude response problem (they're not flat), the DSP units can fix that.

No simple EQ (and that is what the DSP units ultimately are) can fix a problem in the time domain.

If you have lots of time and money, try it and see. I've heard the results, and it doesn't sound like music.

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Do these work? Tact Audio makes one. Does anyone else make them? Asked on Architectural forum, but no response.

You are persistent. Here is the response I gave you on the Architectural forum.

Audyssey has one for $2,500 plus a dealer kit for $325.

See http://forums.klipsch.com/forums/thread/916570.aspx

Do they work.


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Maron's right to a large degree. Once it's "corrected", you can move your head into a "void" area for certain frequencies. There's certain places, however, in rooms wherein it will be immaterial if there is a null/void. Keep in mind where you will generally listen to music/movies, etc. E.g., If no-one ever sits next to the wall window, then removal of the window in the pursuit of perfection is likely wasted time and money.

So from one perspective, it's sorta yes, and sorta no........... Take the Audyssey used with the Denon systems. It takes 6-7 mic measurements in different places, so...... it probably "generalizes" with the best "place" in the room being the "primary" listening point. That system claims to take into account time delay. probably does, but I'm not an engineer, so I'll leave that to someone who (a) knows how that system works and (B) has one.... I have one, I think I understand how it works, but I only use that AVR amp in the living room with a bunch of Heresy's. Wife and kids watch movies, etc., and stay out of the "man cave"..... That room can probably never really be treated due to the design and the consequent speaker locations that I'm stuck with. So, it's a compromise, and seems to work for that application (they sit on the couch and recliners and they love it...)

In the absence of room treatment, which probably many members can't do too much due to space restrictions, room design, furniture, WAF required clutter etc., it can even things out, but it cannot overcome the "nulls" or voids that result from the comb filtering, etc. I'm in the process of building a "good" stereo room. K'horns in the corners, and a pair of Cornwalls as centers. That's it, no "wall of voodoo" with multiple Klipschorns, C'walls, LaScallas and a bazillion Heresy's stacked up like some weird demented attempt to recreate the last Pink Floyd concert I attended, etc. Treatment, you betcha! The sides and back wall will, perforce, have bookshelves/record shelves, and I'll use the books and records in various configurations (using measurement) to compensate for nulls and other sonic "glitches". When I get that far, then I'll break out the DSP/ Audyssey and see what it does. If it sucks, then out with the AVR and back in with the 2 channel amps and I'll use the old style, imprecise method of balancing for where I like to sit.

The best question to ask is: Can it work for me if I cannot really do alot of room treatment? Maybe.... maybe not..... It has limitations, and in the case of the Audyssey, they clearly stated in their ads (and over the phone when I asked...) that it will not overcome room "problems" that require treatment of some sort.

Here's a thought.... Contact Dr. Who and borrow/lease, etc his setup laptop which he's kindly offered to lend to forum members. Do the deed with his equipment. Do as much treatment as you can afford (or the WAF allows), etc. THEN consider DSP to "finish it up". That may be the best or most cost effective method to follow. The old "hot rod" analogy applies here; speed costs money, how fast do you want to go? In this case, how good do you want to have the room. Past a certain point, the cost of treatment gets exponential..... So the DSP may be the ticket after a certain point.

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I think one of the best ways I've heard DSP described is to claim that it is really no different than changing to different source material (ie, a different song). In the end, the room is still going to introduce the same sonic effects (because the room hasn't changed). You might be able to find source material that doesn't excite the room as negatively, but it's not going to be the same as if the room was treated (where you don't have to worry about exciting negative behaviors).

So at best, DSP is a band-aid that can only be applied to a single listening position. If you think the few thousand for the Tact device is worth it, then by all means go for it. If I were to experiment with such a device, the Tact is probably the route I would go.

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I am still fascinated by the inordinate lengths folks will go to to find a magic box to do something that most have no clue as to what must be done.

DSP solutions seem to be pushed by those flatlanders who still persist in living in the frequency domain who feel that if they can only flatten the frequency response at a given location that this fixes room response. Sorry folks, but nothing could be further from the truth. Oh, we may see pictures of an impulse response and even here talk of the time domain, but they are doing nothing in the time domain.

So a box that can ONLY affect the direct signal is going to somehow modify the direct signal and thus change the signal alignment of the MANY reflections resulting from the direct signal - it will change the arrival time of each of the myriad reflections that contribute to the superposition of the resultant signal as a give spot and which changes radically just a few centimeters away in order to do what? To flatter the frequency response? It certainly can't rearrange arrival times of reflections to change localization and intelligibility factors!

Let's see, most of the cues we interpret are in the time domain. And to change superposition, and more specifically, to impact intelligibility, we must have control over the timing - the signal alignment - of both the direct signal and each reflection. But the reflection is a secondary effect of the direct signal. So I guess this will magically align the direct and reflections in time?

No? Then you don't have it. And you lack a way of effectively changing the time and frequency aspects of EACH derivative reflection independent of each other and independent of the direct signal.

And then to suggest that you can average the signal arrival times from multiple locations to obtain an accurate relation of derivative signals in one or more places? HUH???

So what is the goal? A fancy EQ? Flat frequency response? So it assumes that the program source has a flat frequency response to begin with? And now EQ and frequency manipulation can correct for time issues? Sorry, but give me a minute to climb back into my chair as I am busy LMAO.

{BTW, if it could effect the signal/time arrival of individual reflections, why are they using it with a 5 or 7 channel system? If this is possible to the degree they claim, it can effectively replace the additional 5 or 7 speakers in your HT setup! So why are they just flattening the frequency response instead of creating complete and accurate 5.1 or 7.1 systems? And to carry this one step further, if it can do this, it could also replace the L/R front pair of speakers with one speaker and still create the accurate spatial cues both front and back and side to side and up and down that your ears use for localization. In other words, one speaker could effectively replace your 5.1 or 7.1 setup.But they don't...hmmm.}

Is DSP worthless? Of course not! But can it do what they are claiming to the degree to which they claim? No.

It is funny...when I was teaching university physics, as I was also 'working music' most nights and getting home quite late, I used to give students my home phone should they try any problem and get stuck so that they could call for help - well, any night except the one before the weekly assignment was due. In other words, if they got stuck after trying a problem, they could call and essentially receive a private tutorial session - plus they would have the answer (and perhaps understand how it was found! - hey, I can dream!) I used to lamentably joke that if we dug big holes all over the campus and camouflaged them, with the penalty for their falling into one being that we would give them the answers and the necessary help, that we would discover a campus populated by folks crawling around on their hands and knees desperately trying to avoid falling into a pit! As the students who consistently called were the ones who started early and seldom needed help! But the ones needing help were no where to be found!

And so it is with 'audio'. And let me qualify this further by saying 'home audio', as these novelties and debates are less common in 'pro audio' arenas, and they certainly constitute a much smaller portion of the market. Far be it to become familiar with what is actually a rather simple subject area, when it is so fascinating to scour the web trying to find a magic box with a gobbledygook explanation and a high price tag. It seems that 'home audio' is the last to hear the description that is akin to a story passed from person to person to person that morphs via the subsequent generations of repetition. Perhaps this is aggravated by many not having formal education in many of the process areas of the field as well as that many of the claims are not better filtered and scrutinized. All I know is that in 'home audio' discussions are still dominated by debates of how to reduce frequency based crossover anomalies with fancier passive crossovers in speakers and how to EQ room anomalies. Perhaps part of this is because some hear the reference to treating room modes as being focused upon particular 'frequencies' and assume that it is a frequency domain issue instead of realizing that the real issue is the time based persistence that constitutes the resonance which is the problem. But in any event, in other audio arenas over the past 20 years, the nature of these issues has seemed to become more understood or just 'more communicated' with at least a greater tacit acknowledgment of the fundamental time based issues then in the home environment.

May I suggest that many quit crawling around on their hands and knees and get up and simply become familiar with the basic foundation for analyzing and modifying a room. And quit trying to find which site sells magic panels or boxes and discover what it is that we are trying to control, how we control it, and what the result is. Like so many students, if you simply tried to understand and asked for help when you get stuck, you would be much further ahead of those who are simply trying to avoid understanding the subject and who simply want a magic solution.

The subject isn't that difficult at all! Especially if you can forget much of what you think you know just for long enough to learn the current models.


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May I suggest that many quit crawling around on their hands and knees.....

Awww, I like crawling around, especially when it has nothing to do with audio.

That's quite OK Roc...

As long as you are looking for a solution as opposed to trying to avoid it![:D]

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