[zybar]

Ok, below is the graph from my initial measurements with the 2.2x using their pre-calibrated mic at my listening position.

I am not posting this to start a thread where people trash either the VMPS speakers or the Tact preamp.  I am posting this because many people asked me to and to facilitate an intelligent discussion on how measurements translate into sound.  

As you can see form the graph, I had mostly dips and not peaks.  I can try and address some of these dips by changing the pots on the RM 40's before applying the room correction.

George

[jermmd]

George,

How do I interpret the results?  It looks like a line for the Left and Right speakers.  What is the green with orange dots line? How is the straight baseline (?flat or refernce line) determined.  Finally, I thought it was best to lower peaks without raising dips.  Could this be done by simply lowering the straight line to where -10db is on the graph and lowering all the frequencies above that line?  I realize this is likely not so but I want to have a better understanding of how this all works.  Reviewing this graph, I wonder how important all your room treatments are.

As far as trashing your system/speakers, I think we can all take it for granted that you have a superior sounding system that very few people could match.  Many of us have heard your system and would surely agree.

Joe M.

[zybar]

The green with orange is the correction curve that is applied by the 2.2x preamp.  The other two lines are the L/R speakers.

I believe the room treatements are very important and that the measurements pre-correction would be different without them (especially in the bass region).  Also, keep in mind that many of things that room treatments do aren't going to show up in this type of graph.  There are time and phase graphs as well as other graphs that the Tact produces.

To be honest, I am novice when it comes to this area and I am hoping to gain some better understanding and knowledge.  

George

[ctviggen]

Wow, that final curve is amazing.  It's darn flat out to about 10k.  I wonder why the 10k-20k range drops off like that?  Is this with or without subs?  I don't think that the unmodified version is too bad -- most of the stuff is within 5 dB, which supposedly isn't bad (according to Ethan Winer of realtraps).  The left and right speakers are fairly well matched in your room, except for the less than 200Hz frequencies.

[zybar]

Wow, that final curve is amazing.  It's darn flat out to about 10k.  I wonder why the 10k-20k range drops off like that?  Is this with or without subs?  I don't think that the unmodified version is too bad -- most of the stuff is within 5 dB, which supposedly isn't bad (according to Ethan Winer of realtraps).  The left and right speakers are fairly well matched in your room, except for the less than 200Hz frequencies.

Bob,

No subs, just the RM 40's at this point.  I too wonder why the drop-off above 10k.  I will run some tests by turning up the tweeter L-pad and running a new measurement.

Since I had the first pair of RM 40's I have had a difference between the two speakers when measuring output below 200Hz - must be the room.

I agree that the pre-correction was pretty darn good sounding, but the corrected is sound is a different level (as Joe and a couple other friends have heard first hand).

George

[mac]

I too wonder why the drop-off above 10k.

Take a measurement 1m on-axis with your tweeter.  You should see less taper above 10kHz and the response should look smoother.

[zybar]

I too wonder why the drop-off above 10k.

Take a measurement 1m on-axis with your tweeter.  You should see less taper above 10kHz and the response should look smoother.

Mac,

Silly question...

Since I am creating the correction curves based on measurments I make at my listening spot, what does it benefit me to measure the tweeter 1M away?  

George

[mac]

I too wonder why the drop-off above 10k.

Take a measurement 1m on-axis with your tweeter.  You should see less taper above 10kHz and the response should look smoother.

Mac,

Silly question...

Since I am creating the correction curves based on measurments I make at my listening spot, what does it benefit me to measure the tweeter 1M away?  

George

Doing so might help answer your question about HF roll-off.  

Does the Tact allow you to vary the amount of smoothing it applies to your measurement?  Placing the mic closer to your speaker (1m) is my way of having that question answered.  

[zybar]

Ask an obvious question and get an obvious answer...  

I can create my own correction curves with the Tact and/or use dozens of prebuilt curves.  I really need some time to learn how to do many things with the Tact.  I haven't begun to use the true capabilities of the unit.  

George

[eico1]

Since I am creating the correction curves based on measurments I make at my listening spot, what does it benefit me to measure the tweeter 1M away?

I think a speaker that measures flat in the nearfield will be rolled-off at the listening position due to the impedence of air and that will sound more natural than one that is flat at the listening position.

Does this sytem have some way to avoid eqing based on late reflections?

steve

[denverdoc]

Unless I miss my guess, the target curve is deliberately done that way--based originally on I believe a lot of measurements done at various concert halls which typically add some bass boost and roll off the high frequencies ever so slightly; many prefer such a curve to a rigorously flat one which seems etched and a bit thin.  of course I may be all wet, but just a guess given your newness to the unit and that flat out to bat terriroty is certainly well w/in the big VMPS ability,

Looks like a fine unit: enjoy!!!
John

[mac]

I uploaded some DEQX measurements of my own system.  Note that what you'll be looking at are raw driver measurements and DEQX calibrated measurements.  None of those curves show the room acoustic correction capability of the DEQX.    

http://www.audiocircle.com/circles/modules.php?set_albumName=albur18&op=modload&name=gallery&file=index&include=view_album.php

[denverdoc]

Mac,

That is simply astonishing! What sort of averaging and sampling windows were used? That's flatter than my garage floor. BTW, in ref to my earlier remarks re the possible psychoacoustic undesireability of flat response, what are your thoughts--have you tried different targets other than flat?

J

[mac]

Yeah, it's pretty flat.     After you've performed a calibration you can use their software to EQ the curve to your preference.

This is a good read if you haven't alread seen it: http://www.deqx.com/downloads/What-is-DEQX-Technology-Whitepaper.pdf

I don't want to hijack this thread so I'll refrain from posting off-topic.  Cheers, mac.

[JoshK]

I'm no expert here either but judging from the pictures I have seen of your room you sit relatively far away from the speakers, especially in relation of the speakers to side walls so I think those measurements are quite good actually.   I think if you took the measurements nearer field you'd get even better measurements because you would get less room (particularly if your measurements were gated).  This means nothing though in this case as you don't sit near field so it isn't really all that helpful. OTOH, it may give you an idea of the ratio of direct to reflected sound.  

I am surprised at the deviations of the two speakers below 200hz.  Not that it is so hard to believe but I haven't actually seen it before shown like that.  Wow, rooms really do affect the sound....by the looks of it, a lot!  But the mid/highs track super tight....weird.

[ctviggen]

I sat at my normal position one day, then moved my head forward and backward until I found a better position.  I then moved my seat into that position.  I find near field to be better.  However, have you seen the videos at the realtraps site (www.realtraps.com)?  Ethan moves a microphone mere inches and gets dramatic changes in response at certain frequencies.  Of course, this was done for effect, but if you're near a null/large peak, it can't be good.  I have the same right/left differences, because I have a fireplace right near my right speaker but smooth walls/doors near my left speaker.

[Val]

None of those curves show the room acoustic correction capability of the DEQX

mac, are those speaker or room correction curves?

Val

[mac]

None of those curves show the room acoustic correction capability of the DEQX

mac, are those speaker or room correction curves?

Val

As I tried to point out, those curves show the crossover and calibration capabilities of the unit.  This curve shows a simplification of what it can do for room correction.  PM me if you have additional questions.  Cheers, mac.

[sys1]

George-

As I said in your other thread, the key is reducing the peaks not boosting
dips.  Draw a new target that follows the response of your speakers bringing down the peaks.

After you've created a new target curve and programed the presets,
go into the DD screen and take a look at the correction curve you've created and make sure you not exceeding 0db anywhere along the
curve. If you boost past 0 db you'll clip the correction filters and degrade
the sound quality.  If you exceed 0db anywhere, go back in the correction screen and lower the level of your target curve, reprogram and check it
again.

You really need to go to:

http://groups.yahoo.com/group/TAUGSOA/files/Audio%20TacTility/

and down load this users guide to fully understand how to use your TacT.

[sys1]

George-

As I said in your other thread, the key is reducing the peaks not boosting
dips.  Draw a new target that follows the response of your speakers bringing down the peaks.

After you've created a new target curve and programed the presets,
go into the DD screen and take a look at the correction curve you've created and make sure you not exceeding 0db anywhere along the
curve. If you boost past 0 db you'll clip the correction filters and degrade
the sound quality.  If you exceed 0db anywhere, go back in the correction screen and lower the level of your target curve, reprogram and check it
again.

You really need to go to:

http://groups.yahoo.com/group/TAUGSOA/files/Audio%20TacTility/

and down load this users guide to fully understand how to use your TacT.