[roscoeiii]

I am just going through possible setups with the Dual Core and was wondering what others were doing about the drop in low end response following calibration? 
I'm experiencing a 6-8dB lowering of the bass range (below around 200Hz) following the typical calibration.  When using my main speaker only, it sounds like when you have one speaker out of phase from the other.  The is very little low end.  I have been try to use the House Curve to increase the low end to make things listenable.  I'm creating more questions then I have answers for.  I'm not feeling the love so many of you are expressing.  Any ideas would be welcomed.

Well now you know that you don't prefer a flat frequency response. Easy enough to boost the bass by the 6-8 dB you like. But running the DSP and then boosting will give you the bass levels you like and the benefits of DSP.

[sparky62]

Roscoe, I do like the flat bass response sound over the unprocessed bass sound.  It is the level, as compared to the mid-range, that is the issue.  After the typical calibration the 25Hz to 200Hz range is dropped 6-8dB below the mid-range in my system.  That is the issue that I was asking about.  I'm thinking there must be someone who has worked on this drop in level and could share their settings for the house curve that sounds best in their system.

I'm find it a difficult to A/B, due to the house curve having to be reset to flat as an additional step each time I compare the calibrated to the non-calibrated.  Also, the change in volume that is automatically done by the DC whenever the house curve is applied is yet another complication to the comparison.

[Guidof]

I am just going through possible setups with the Dual Core and was wondering what others were doing about the drop in low end response following calibration? 
I'm experiencing a 6-8dB lowering of the bass range (below around 200Hz) following the typical calibration.  When using my main speaker only, it sounds like when you have one speaker out of phase from the other.  The is very little low end.  I have been try to use the House Curve to increase the low end to make things listenable.  I'm creating more questions then I have answers for.  I'm not feeling the love so many of you are expressing.  Any ideas would be welcomed.

Is the 6-8dB drop referred to your "before calibration" room response or is it referred to an ideal flat response?

Also, what is the shape of the curve below 200Hz "after calibration"? And the full range response?

To better assess what's actually happening, it might be helpful if you could post the graphs of your measurements.

It might also help to know something about your speakers and room.

Regards,

Guido F.

[sparky62]

Guidof, The 6-8dB is in relation to the after-calibration response graph, using the mid-range as "0dB".  The after calibration graph below 200Hz bass range is quite flat, just 6-8dB below the mid-range.  I'll post some pictures of the screen soon.  I am currently only trying the AMDC as a processor (digital only).  I plan to move on to use it as a DAC, and then a preamp. 

My system is: Squeezebox Touch (digital) -> AMDC (digital) -> Emotiva XDA-1(analog) -> Spectral DMC-6 -> Parasound Halo A-21 -> Magnepan 3.6R + Boston Acoustics PV-1000 sub.  The AMDC would replace the XDA-1 & the DMC-6, if I keep it

My room is 37' X 15' X 8.5'.  I listen near-field (~9'), 3.6R out ~6' from the short front wall, sub center between the Maggies.  I preferred no sub for music, before the AMDC, now I like the sub on for music, if I could only get the level of the bass range to be in line with the mids.

[rodge827]

My room is 37' X 15' X 8.5'.  I listen near-field (~9'), 3.6R out ~6' from the short front wall, sub center between the Maggies. 

Sparky, You have a large room.

Try moving the sub to the nearest corner and turning up the gain on the sub amp. 

Then do a calibration and see if it helps your bass response.

I had my two subs next to my monitors and by moving them to the corners and turning up the sub amp worked well for my room.

Chris

[Guidof]

Guidof, The 6-8dB is in relation to the after-calibration response graph, using the mid-range as "0dB".  The after calibration graph below 200Hz bass range is quite flat, just 6-8dB below the mid-range.  I'll post some pictures of the screen soon.  I am currently only trying the AMDC as a processor (digital only).  I plan to move on to use it as a DAC, and then a preamp. 

My system is: Squeezebox Touch (digital) -> AMDC (digital) -> Emotiva XDA-1(analog) -> Spectral DMC-6 -> Parasound Halo A-21 -> Magnepan 3.6R + Boston Acoustics PV-1000 sub.  The AMDC would replace the XDA-1 & the DMC-6, if I keep it

My room is 37' X 15' X 8.5'.  I listen near-field (~9'), 3.6R out ~6' from the short front wall, sub center between the Maggies.  I preferred no sub for music, before the AMDC, now I like the sub on for music, if I could only get the level of the bass range to be in line with the mids.

This seems definitely odd. It would be interesting to see your room response curves (full frequency range 20Hz to 20kHz). If the situation is as I think you describe it, the only cause that may fit the picture might be a house curve accidentally set for a 6dB cut. This seems very unlikely, though worth double checking perhaps (I know, I'm grasping at straws here). Right after calibration, however, house and tilt curves, as all EQ bands, are set to "disabled" so the cut would not be apparent until the house curve is manually enabled.

Have you tried perhaps redoing the calibration to see if you get the same odd cut? Any chance there is some low frequency background noise (heating or air conditioning fans) interfering with the calibration process?

Do post your graphs, if possible. Better if downloaded into your PC and displayed in REW or similar. The Dual Core screen is really too small to be able to make much sense when displaying the whole frequency range.

Regards,

Guido F.

[sparky62]

Hello again.  I have not had a chance to try any of the suggestions, but I do have some pictures of the DC screen.  Sorry for the blurry pictures.

First is the before and after(w/sub).  The suck out on the right side of the picture is the dipolar cancellation that corresponds with the Maggies distance to the front wall.


The dip in the 28Hz-42Hz range is just sub-woofer crossover/level matching.  I am NOT addressing that in this discussion.

In the following pictures I have set the cursor to positions that illustrate levels I am addressing.  You will note ~8dB drop in the corrected bass range, below 200Hz.
Next is the after cal curve with the cursor at 101Hz, note -8.4dB level.


Now the same curve, cursor at 196Hz, note -0.1dB, cursor is at the extreme right edge of screen



Thanks for your input.  I will be listening/adjusting ASAP.

[roscoeiii]

I would try to expand the range corrected by the DSP. The dip in dB overall, may be due to the big node dip around the where the DSP ends in its stock settings. You can consult the manual to see how to expand the DSP range out to up to 500Hz (or so, forget the exact limit).

[neekomax]

Sparky, other bros,

This is my post from when I first brought mine home a week and a half ago, and ran the basic calibration. Look familiar?

[rodge827]

Chris, I know you have a BPS that works well...do you know of anyone willing to put something like it together for others who may be interested?

Here is the email of the guy who made my 12v battery power supply:   bcengines@comcast.net
His name is Brian and said that contacting him directly would be best to figure out each persons need.

Chris

 

[Guidof]

Hi sparky62:

Thanks for posting the before/after graphs. If I understand it correctly, these show a drop of about 8dB relative to a one point measurement (to the extreme right of the screen). This does not necessarily mean the bass relative to the midrange is also down by the same amount. A graph of the full frequency range would better identify if and were there is a drop. It would perhaps clear things up if you could dump your full frequency measurement into your PC and import it into REW, so that it can be saved as a .jpg file and then inserted in a post. That would give us a really good idea of what the overall response is. As mentioned earlier, the small size of the DC screen makes it really hard to figure things out, especially when dealing with the full frequency range.

Regards,

Guido F.

[neekomax]

I have a question: If I have a calibration set in Profile A, do I simply need to select Profile B, back out, and do a new calibration in order to have a second correction to compare to the first afterwards?

[rodge827]

I have a question: If I have a calibration set in Profile A, do I simply need to select Profile B, back out, and do a new calibration in order to have a second correction to compare to the first afterwards?

Yes, you can do it that way.
When I got mine mostly dialed in on Profile A, I went to the other Profiles and picked slightly different levels to calibrate and compare.

[Guidof]

I have a question: If I have a calibration set in Profile A, do I simply need to select Profile B, back out, and do a new calibration in order to have a second correction to compare to the first afterwards?

It depends on what you intend to compare. If you want to compare two calibrations (e.g., by calibrating for different positions of the mike), that would be the way to do it. But if you merely wish to add an additional calibration spot, you don't need a profile, just do a multi-point calibration.

If, on the other hand, you wish to compare different settings of house and tilt curves or of the parametric EQ, then you only need to calibrate once. Each newly created profile will automatically contain the original calibration set in profile A but will have whatever new EQ settings you give it.

Regards,

Guido F.

[sparky62]

Guidof, Your suggestion about increasing the frequency of correction above 200Hz helped.  I ran a calibration up to 500Hz and the transition is less sever. 

In this picture, the response curve shows a bit flatter line on either side of the null at ~170Hz.



Here is a full 20-20k curve.  Boy is that ugly!


I don't consider this situation to be solved, but a long with House Curve & Bass level it is a step in the right direction.  Regarding loading the DC screens into a PC, I no longer have a laptop (iPad), so I will have to unhook the DC from my listening room and tote it up two flights to my desktop.  I will try that soon.

On a separate (non-bass) note.  I had noticed a loss of sound stage width and air when using the DC, compared to the pre-DC system sound.  I also read a couple of comments at the end of the Absolute Sound review that jived with what I was hearing.  I then rigged up an experiment on my Maggies as follows.  I placed one of my 2'X4' on-wall sound panels behind each Maggie on milk crates and leaned them against the back of each speaker.  I then ran a calibration for this setup.  Following cal I returned the set up to normal.  In essence I was trying to "trick" the DC into hearing (mostly) the front radiation of the Maggies.  I now had two profiles to compare and I prefer the "tricked" profile.  The sound stage has returned to almost the width it had.  The DC must process the full spectrum and work to control the room decay that, in the case of panel speakers, is necessary for the stereo presentation.

[neekomax]

I guess no one noticed my (re) post of my original before/after graph. The reason I did so is that it looks a lot like sparky's in the way that the bass seems to have been pushed down at least 6 dbs overall in relation to the mids, which you can start to see on the right of the graph. My solution, since my speakers have active bass, is that that I did another calibration with gain on the subs down from about 12:00 (where I normally have them) to about 10:00. Then, after calibration, I have turned them back up to about 1:30. This has pretty much fixed the lack of bass post-correction, although I'm still not quite happy with the sound yet.

Perhaps the reason the DC does this is that, since it doesn't want to/can't boost the nulls, it cuts the peaks down to where the average response is down from the rest of the spectrum, but flat (isn).

Another question: When using advanced calibration, the 'compensation' setting sets the amount that the DC boosts the bass overall post correction (I suppose as a measure to address the aforementioned effect), correct?

Sparky, other bros,

This is my post from when I first brought mine home a week and a half ago, and ran the basic calibration. Look familiar?

[Guidof]

@sparky62: Your full frequency graph looks a lot worse than it is. I know it's a PITA to drag the DC to where your PC is, but I think that you'll see a much nicer curve on the big screen. Still, you do seem to have a bit of a dip in the bass, which maybe the result of the DC cutting down the peaks in the low frequency region and also a function of how your Maggies interact with your room.

If your setup allows, you may want to try alternative locations for your Maggies to compensate for the effect. For example, I found that by bringing my Martin-Logan SL3 dipoles 10" closer to each other, i achieved a much cleaner and more balanced bass rendition, to the point that I had to disable my house curve, previously set for a 2dB boost.

Best wishes for further fine-tuning!

Guido F.

[Guidof]

@ neekomax: As you also found, because the DC smoothes down the room modes and does not apply boosts it tends to cut the low frequencies, especially when a system would tend to roll off the bass a bit were it not for the presence of room modes. It seems to me that this effect is more pronounced with 2.0 setups than with 2.1 or 2.2, as one or two subs will fill up the range where the main speakers may (anechoically) roll off.

Personally, I found that repositioning my main speakers had a salutary effect in this regard (see my reply to sparky62). And my REL T1 sub is now set at only 4/40 of its gain and a 30Hz crossover.

Alas, now that I have reached a satisfying tonal balance, it turns out that in a couple of months we will move to a smaller house at the opposite end of the country, with a much smaller music room, so I'll have to start all over again! It's going to be quite a test for the dual Core!

Best,

Guido F.

[Guidof]

As promised, here are my impressions from substituting the AntiMode Dual Core's 9V AC wall wart with a 12V DC CIAudio power supply.

The overall impression is of the same order of magnitude and in the same direction as when I substituted a run of Audioquest Cinnamon (ahem) Ethernet* cable for the garden variety cable I was previously using, that is, somewhat greater clarity and refinement, with more detail, more airy and sweeter highs, better defined bass, and in general a presentation one step closer to the elusive goal of faithfully reproducing a live unamplified event. Also, timbres seem more accurate, which contributes to the overall sense of effortless presentation. And the signal to noise ratio seems better (blacker blacks).

Yes, the difference with using the wall wart is subtle, which perhaps suggest the standard PS is pretty good. But they are worthwhile. And of course, at $350, the CIAudio supply is about one third the cost of the Dual Core, so one would have to consider this before opting for the CIA. Personally, I'm satisfied that the improvement, in my system, justifies the cost.

*And of course, we all know that Ethernet cables cannot possibly affect sound quality.

Guido F.

[sparky62]

Guidof, Thanks for your impressions of the differences in power supply.  I've been wondering about that since I first hooked up the AMDC.

I have been out of town helping my 93 year old father get ready to sell his house and move.  Wait, that makes me really old.   

I have re-run my calibrations and I am happier with the upper limit set to 250Hz (from 500Hz).  The biggest sound improvement I have found was using the Compensation to fill in the mid-bass to bass range.  I learned to use the Compensation from a news letter in the AMDC box.  I don't know if it is available on the Web.

Good luck with your move.
Jim