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Do you hear what I hear?


luvdunhill
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Many times I have wanted to ask someone to listen to a recording and compare a few notes, mostly around system "voicing" and dialing things in.

So, we will see if there is interest to help.

First request is Bill Evans "Waltz for Debbie" APJ 009 (vinyl). If you have a different format or mastering, then that could be interesting as well.

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No vinyl for me, but I was looking for this on Tidal.  Same cover so I think I got the right version. 

Very nice on my Maggie's.  Need to do some more critical listening with my 007's this evening.

So, my question is: is the bass-line way too overbearing to the point of being unnatural? I love the ways the drums are recorded - they are spot on and sound amazing on my setup. Very realistic. But the bass is hard panned left and just is "distracting". Now I have some system things going on around these frequencies and the top end of the bass (the high notes) comes though my top horn and the the bottom though the back-loaded "bottom" horn. I have tried a few other recordings (though no other Bill Evans Trio) and this one stands out as either sounding "unnatural" or just flat out "wrong".

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Sounds like a room node or other resonance, just from your verbal description.


That is possible. I need to setup a measurement microphone for that though. I don't like that I can hear the transition down the horn, but other tracks don't seem to accentuate that. Perhaps another recommendation of a similarly mic'ed / composed group I could compare with?
I have the AP cd.  The bass sounds fine to me.


Would you at least say it's "unbalanced" compared to the other ensemble parts?
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On the CD, the bass is definitely almost entirely on the left (and Evans is mostly on the right).  Just a recording quirk, but it might make the bass seem overbearing, depending on your setup.  I'm listening with headphones, now (RS-1), and the channel difference is fairly irritating, but that's just how the album is.  The bass line, even on headphones, isn't any louder than anything else, particularly.  You can tell that the bass was miked fairly close.  The drums are pretty well centered.

Edited by EdipisReks1
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I've always had a bit of an issue with the placement of LaFaro's bass but I've always put it off as being picky since this is an otherwise, perfect jazz trio recording.

I listened to it on my studio system which has okay room acoustics (with some bass treatments and eq) and the bass doesn't stand out as much as my main speaker system.

On my main system the bass is similar to what you describe. That room does have issues with peaks in the 60 and 120Hz ranges which would account for the booming, forward nature of the bass. It's made worse (I'm guessing) by the fact that the bass is hard panned to the boomy side of the room. 

I suggest you try reversing the channels to see if that makes a difference or try summing the channels to mono in your ULN-2. 

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I may take you up on that. Just ordered an LP so I have a shipping container.

I think I have a channel imbalance. I swapped out my preamp 6SN7 (single gain tube for both channels) to a Ken-Rad black glass and things moved a bit to the right (and got a bit fuzzier). I need to make a few measurements, but too lazy now.



I stuck the offending tube in a cheap B&K 600 and both sections showed about the same amount of "green" on the scale, but not sure if that means anything. The output is a split load inverter to convert to balanced - again a single tube for both channels. Not sure if an imbalance could develop here or not.
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If you want to look at room modes, there are a number of apps for smartphones that should work quite well.

I actually have one of these http://www.xtz.se/product/room-analyzer-ii-pro - well actually the earlier version. But they are dead easy to use; in USD it is about $270 (or a couple of hundred quid in across the pond money, where I lurk), and use a laptop to run the software. And if you put the microphone bang on the line of symmetry of your speakers you can check for matching irregularities by storing the frequency response of (say) the left speaker and then overlaying the right speaker.

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I have not, but have heard they can work well - the microphone in a smartphone seems to be of very high quality with a rather flat frequency response. I'd have to poke around on the web to substantiate that, but recall I've seen this written down.

But I bought my XTZ unit a decade ago before smartphones were the palm sized high grade computers they now are. If I were doing measurements starting right now I would certainly research what the capabilities of my phone were and what were the best apps.

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Looks like a perfect storm. General channel imbalance as well as something happening around 100 Hz.

The orange color is the left channel.

luvdunhill - combined .png

Now, that is with the full-rangers and extension subs, two measurements (one per channel).

If I split it out into four measurements and then a single measurement with everything on in stereo (the black line), I get:

luvdunhill - combined.png

In this case, the left channel colors are "green" and "orange".

So, I guess my question is, can I attribute this to the room, or is there something else going on in the chain....

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I'm guessing the big bump at 40-50hz is an interaction of your subs and room. That's so low that some drums and organ pedals live around there.

The problem you're hearing is the big right channel suck and the left channel bump at 80-100 hz.

Unfortunately, pretty common problem with your typical american room.

I suggest installing some corner bass traps. Not the foam jobies (which are worthless IMHO) but some thick (4-6") 2x4' panels. I have some Real Traps in my studio and they really make a huge difference. 

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I would revisit the subs.  The full-range speaker response overlaps at the 100Hz region, but the difference between the two subs' responses are worse than those on the combined graph.

I would also recommend playing around with the individual phase of the subs.  If you make left sub "fight" the full-range driver in the crossover region, maybe it'll temper it?  Wouldn't know if the damage is worth it without trying it, though.

Finally, can you make a 2.1 system, and ditch left sub entirely?

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I can't really get rid of that 100Hz problem with crossover slopes or frequency. I have somewhat addressed the channel imbalance though?

I applied the mic calibration file, which really ends up showing a lot of high frequency attenuation in the final graph. I'm surprised about that. I also setup the automatic correction.

Here's green is the right channel:

EOD2.png

Splitting it out (again greens are right), with Half-Hanning windowing:

EOD1.png

 

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