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guf

upgrade that's not feeling like an upgrade

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So I had my system really dialed in.  La Scalas,  the usual mods and then some -  tweeter, woofer, ES crossover. They were sounding great. It helped that i got a turntable and have been mesmerized by the vinyl sound.  I thought how the next logical thing would be some kind of mid range horn upgrade.  I tracked down a elptitrac 400 and B&C dcm50. Then... wondering how I was going to fit the horn into my La Scala a pair of Belle's came up for sale locally. I got them.  I thought, I'll get these and not have to cut up my La Scala.   They would fit right in.... I took delivery today and I will have to adjust a little to make them fit in the Belles.  So they are sitting on top.  

I have been listening all day and I can't seem to get them to sound right.  The sound is big and clear and detailed but I lost some depth and soundstage. And I have to say these were the strongest points of my system before. Maybe that sound wasn't "right" before and i got used to it?   I have been messing with placement and adjusting the taps on my ALK crossovers but i don't feel like I'm getting the magic back that I had.  Any thoughts or suggestions?  before and after pics.  

IMG_1677.jpg

IMG_1320.jpg

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You may be having some time alignment and related acoustic

Issues. Nice system. 

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ok. I did this to one. Could something like this effect the time alignment?  Even just doing one speaker, gave me some depth and center image. 

IMG_1680.jpg

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Won't change time alignment much, but having the bass and mid horns closer together is better for their crossover region.  Was going to say that a minute ago but opted instead to ask the question, which should still be answered...

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Bells were ok not better than the Modified La Scalas so I transferred stuff over and they sounded better. Then tonight I got the horns. Lots of changes is 24 hours. I thought with my ALK ES crossovers *** helped with the time alignment? 

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3 hours ago, guf said:

...I tracked down a Eliptrac 400 and B&C dcm50. Then...a pair of Belle's came up for sale locally. I got them...I will have to adjust a little to make them fit in the Belles.  So they are sitting on top.  

I have been listening all day and I can't seem to get them to sound right.  The sound is big and clear and detailed but I lost some depth and soundstage. And I have to say these were the strongest points of my system before. Maybe that sound wasn't "right" before and i got used to it?   I have been messing with placement and adjusting the taps on my ALK crossovers but i don't feel like I'm getting the magic back that I had.  Any thoughts or suggestions?...

 

IMG_1677.jpg

 

I thought with my ALK ES crossovers *** helped with the time alignment? 

 

You've almost certainly got time alignment AND phase response issues with the higher-order filters that ALK crossovers use, along with the change in the midrange horn and driver.  This is easy to see if you had a plot of measured phase vs. frequency from a microphone (as well as the commonly seen SPL vs. frequency from the same measurements), both before and after the changes you show. 

 

The problems that you report in your subjective listening are not related to width of the crossover interference bands, unfortunately...but rather more likely the phase shifts that are incurred by using steeper slope filters (i.e., there is no free lunch--especially with passive crossovers) and the different horns/drivers.

 

Perhaps if you invested $110 in a calibrated USB microphone and microphone stand, loaded REW onto your laptop, then ran a measurement, you'd see the problems--instead of guessing what's occurring.  Then you would be able to make informed decisions.

 

Chris

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For every "order" in a crossover there will be 45 degrees phase shift, opposite directions for high- and low-pass sections at the spec'd frequency.  A first-order symmetrical will have 90 degrees separation at the crossing point; second-order (12 DB/octave) will be 180 degrees apart ("complete" out of phase w/ each other), etc.  I'm a little foggy at the moment but am thinking the high-pass will be the "leading" and the low-pass the "lagging", so, for example, the tweeter / squawker "time alignment" will be made worse rather than better for each "order" of the network.  An "extreme slope" implies a higher-order crossover filter, thus even greater separation.  So, no, it will not "help" with "time alignment" unless, perhaps, the frequency, the order, and the differential in driver distance all conspire to bring things into proper phase, albeit not the same cycle of the waveform.  If you grok that, but I'm guessing not, it should answer your question.

 

Apart from physically aligning the drivers, including consideration of the signal phase angles, your best bet is active crossovers / bi-/tri-amping.  I see Chris just now replied as I'm "typing" this, so ignore my expectation bias and listen to him instead.

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Chris, the phase angle vs. frequency plot Danley shows for the SH 50, is that with or without the recommended 4th-order Butterworth 40 Hz high-pass in place?

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:rolleyes:  I don't believe that it's wise to dilute the message in this thread.  Better to address that in the thread that you refer to (EDIT: "without" is your answer).

 

To the OP:  we're basically saying the same thing--you've made a great deal of changes without much hope of miraculously getting it right on the first try--without being able to visualize at least some of what's occurred acoustically from measuring some aspects of the changes incurred.   That's not likely to result in success.

 

Chris

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Also to the OP:  ALK is of the opinion (as far as I can tell) phase angles of the electrical signals (thus of the resultant sound waves) is of lesser importance than other aspects of what's going on.  Chris is (as far as as I can tell) currently leaning hard in the other direction.  While in theory I would tend to side with Chris in this matter, it takes a lot of money for gear, and (a lot of, variably) time to manipulate it.  In my world, which seems to be different than y'alls anyway, time and money are mutually exclusive commodities.  And that, as much as anything, is why I set my standards lower and enjoy what I've got (decidedly mid-fi gear).  I reckon I'm a good 80% of the way "there" compared to most folks, who can't understand the allure, much less hear, much less appreciate the differences.

 

Before you rape those Belles too hard, would you consider selling them, since they're seemingly not really what you want?

 

(Edit:  Chris, I knew that.  Or at least surmised it.  Had to be so...)

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Sell the belles... go back to the la scalas.

Problem solved.

I don't think it really a great idea to chase system customization if you're already very happy with a set up you own... sure you can probably get a custom belle to sound good, but why... unless you're a pure tinkerer enthusiast.

I am not sure how time alignment is going to solve your dimension issue... though it would solve any smearing issues you have.

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1 hour ago, Schu said:

I am not sure how time alignment is going to solve your dimension issue... though it would solve any smearing issues you have.

 

From here (the effects of overall time alignment AND phase flattening):

 

Quote

The difference is a combination related to perceived smoothness of presentation (with significant reduction in harshness), improved soundstage coherence like everything is in focus and spaced out laterally like on a stage, and an overall increase in the sense of realism or immediacy in the room.  It's not subtle, but difficult to pin to one aspect of the presentation--like something as simple as a timbre shift, clarity/opaqueness, or something like that.  The listening effect is extremely pleasant and engaging.

 

This from the Greenfield and Hawksford paper: The Audibility of Loudspeaker Phase Distortion, JAES, 1990

 

Quote

First person: ("A" represents excess phase equalised version)
Within 30 seconds of hearing the second playing the Cantate Domino track he exclaimed that there was no comparison between the two renditions. At the end of the hearing his comments were: "A" was more open, better stereo presentation, solid bass; "B" sounded more like loudspeakers.

 

Chris

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5 hours ago, Chris A said:

 

You've almost certainly got time alignment AND phase response issues with the higher-order filters that ALK crossovers use, along with the change in the midrange horn and driver.  This is easy to see if you had a plot of measured phase vs. frequency from a microphone (as well as the commonly seen SPL vs. frequency from the same measurements), both before and after the changes you show. 

 

The problems that you report in your subjective listening are not related to width of the crossover interference bands, unfortunately...but rather more likely the phase shifts that are incurred by using steeper slope filters (i.e., there is no free lunch--especially with passive crossovers) and the different horns/drivers.

 

Perhaps if you invested $110 in a calibrated USB microphone and microphone stand, loaded REW onto your laptop, then ran a measurement, you'd see the problems--instead of guessing what's occurring.  Then you would be able to make informed decisions.

 

Chris

yeah i got  those mics and stand. years ago... to help with placement and room treatments. gave up and seemed to surivive with out it for the past 5 years

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You're getting a better sound in that room with the ES networks than with what I sold you? Interesting.

 

Group Delay and Time Delay - from Al's paper on the ESNs

 

"The group delay in a filter, which is defined as the rate of change in phase with a change in frequency, comes to a peak just as the skirt attenuation begins. This puts the maximum group delay error contributed by the crossover network, which I will assume to at least be proportional to true time delay, right at the crossover frequency. This would seem to provide a means to partially control the delay at the frequency where both drivers are sounding. The lower the frequency and the sharper the skirts of a filter, the more group delay it has."

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3 minutes ago, guf said:

yeah i got  those mics and stand. years ago... to help with placement and room treatments. gave up and seemed to surivive with out it for the past 5 years

 

Perhaps you should find them and give it another try.  See:

 

Chris

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9 minutes ago, Deang said:

You're getting a better sound in that room with the ES networks than with what I sold you? Interesting.

 

yes. 

but what do i know?

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Maybe the mid horn isn't to your liking. 

Try a k400 on top of the Belle 

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It's an in-between room.

 

Where are you tapped out with attenuation right now?

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2 hours ago, Schu said:

Sell the belles... go back to the la scalas.

Problem solved.

I don't think it really a great idea to chase system customization if you're already very happy with a set up you own... sure you can probably get a custom belle to sound good, but why... unless you're a pure tinkerer enthusiast.

thats an option but i should give it more than 24 hours before i give up.    yeah I am a "tinkerer" cars, trucks, home, food... whatever.   Every time I modded the la scalas i like them better.  

 

 

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