Hi Everyone,
I have a question. I have always felt stepped baffles were cool, but after doing some sims I can't really get the reason.
What I mean is, like several of Troels' designs use stepped baffles, but they are not time-coincident. That is, the step seems to only be alleviating the need for extra poles to assist with the delay, but not really to produce a perfect impulse or (ironically) a step response.
So let's say I have a 2-way already designed, like the LM-1, I'll use it because all the data is already posted and online. It's a simple 2-way with second order symmetrical HP/LP filters.
http://www.diyaudio.com/forums/multi-way/291438-lm-1-diy-speaker-available.html
As built, the woofer is behind the tweeter approximately 1.1"
How and why would you step the baffle for it? How do you calculate the appropriate baffle depth and what benefits would you gain?
Best,
E
I have a question. I have always felt stepped baffles were cool, but after doing some sims I can't really get the reason.
What I mean is, like several of Troels' designs use stepped baffles, but they are not time-coincident. That is, the step seems to only be alleviating the need for extra poles to assist with the delay, but not really to produce a perfect impulse or (ironically) a step response.
So let's say I have a 2-way already designed, like the LM-1, I'll use it because all the data is already posted and online. It's a simple 2-way with second order symmetrical HP/LP filters.
http://www.diyaudio.com/forums/multi-way/291438-lm-1-diy-speaker-available.html
As built, the woofer is behind the tweeter approximately 1.1"
How and why would you step the baffle for it? How do you calculate the appropriate baffle depth and what benefits would you gain?
Best,
E
Have a look at the link below. Who did this LM-1? Its a pretty poor design by many means whose mistakes are camouflaged by a pretty recessed frequency response. I`ve not com accross this LM-1 before.
Linkwitz-Riley Crossovers: A Primer
Linkwitz-Riley Crossovers: A Primer
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Hmmm.
I'm a time alignment guy, 6db or 24db, so stepped helps line up the centers, but you probably know that already.
Otherwise, perhaps stepped baffle helps diffraction, or maybe I've read people liking the step response where the speaker sounds better when the tweeter's tail end response then feeds right into the woofer's leading edge.
"However, the decay of the tweeters' step smoothly blends with the start of the woofers' step, implying good crossover design."
Tekton Design Enzo XL loudspeaker Measurements | Stereophile.com
I've no idea.
I'm a time alignment guy, 6db or 24db, so stepped helps line up the centers, but you probably know that already.
Otherwise, perhaps stepped baffle helps diffraction, or maybe I've read people liking the step response where the speaker sounds better when the tweeter's tail end response then feeds right into the woofer's leading edge.
"However, the decay of the tweeters' step smoothly blends with the start of the woofers' step, implying good crossover design."
Tekton Design Enzo XL loudspeaker Measurements | Stereophile.com
I've no idea.
You don't calculate it - you just make it stepped and hope that you've made smaller difference between acoustic centers of drivers.
Point of Troels stepped baffle use is to make symmetrical crossover slopes - that is his preference. But stepped baffle makes too much diffraction, makes the distance between drivers centers larger and brings much more problems than benefit, in my opinion. Some may claim that it is their preference, but i see no real advantage of it, but lots of disadvantages. I'm tempted to ask him if he did blind AB test to hear if it is his real preference or if he could tell the difference at all - providing that crossover slopes doesn't strain the drivers used in any way and that frequency response is the same. Slanted baffle makes much more logic in that sense than stepped one - but it has it's own set of compromises.
Point of Troels stepped baffle use is to make symmetrical crossover slopes - that is his preference. But stepped baffle makes too much diffraction, makes the distance between drivers centers larger and brings much more problems than benefit, in my opinion. Some may claim that it is their preference, but i see no real advantage of it, but lots of disadvantages. I'm tempted to ask him if he did blind AB test to hear if it is his real preference or if he could tell the difference at all - providing that crossover slopes doesn't strain the drivers used in any way and that frequency response is the same. Slanted baffle makes much more logic in that sense than stepped one - but it has it's own set of compromises.
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Unless you are using 220mm drivers i wouldnt bother with stepped baffle.
But if you are, it will open up the soundstage due to better off axis response.(my theory)
Both horizontal and vertical reaponses gets better probably due to same acoustic center.
But you can get there by using a waveguide aswell.
No diffraction can be seen in 0dg response from the stepped baffle.
I would only use at tilted baffle if i were to build an ortho acoustic speaker in order to get proper ratio between direct and reflected sound.
But if you are, it will open up the soundstage due to better off axis response.(my theory)
Both horizontal and vertical reaponses gets better probably due to same acoustic center.
But you can get there by using a waveguide aswell.
No diffraction can be seen in 0dg response from the stepped baffle.
I would only use at tilted baffle if i were to build an ortho acoustic speaker in order to get proper ratio between direct and reflected sound.
He's usually targeting LR2 acoustic slopes with their reduced phase-rotation relative to higher order filtering; achieving perfect impulse or step responses aren't the main goals. Time coincidence is nice in theory, but given how limiting it is and the questionable audiblity anyway, I can't say I blame anyone for not getting sucked into that game. He's also trying to produce enclosures that are easy to build -they're kits after all.
I can't honestly say I like the potential diffraction etc. myself, but we all pick the compromises that we prefer.
He has, or relatively speaking (since it would be difficult to get things exactly the same). Same speaker with stepped & flat baffles, four different filters (two apiece) with his Discovery W18 project:
18W-8434G00
DiscoveryW18-crossovers
In Troels's case, probably because a lot of people don't want to modify drivers, or buy additional waveguides. He may also simply prefer the direct-radiator approach sans a large waveguide, although he's done a number in the past, e.g. C17mk4
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That's so true. Nothing mentioned so far is superior per se, but depends on implementation and personal preference.
I've read that long time ago. Basically the guy said that "it is his preference" to use LR2 symmetrical filters because "it sounds better to his ears".
While i respect the work he has done, i keep my exclusive right not to agree with every design decision he made. Sometimes LR2 will work better, sometimes not - depending on the concept and the drivers being used.
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As it happens, Troels has tried this - for instance, the Quattro, and several other high-sensitivity designs on his page.
Alex
My wife has better hearing than I do. Whenever I do something different, I ask her to listen. She doesn't get into audiophile descriptions, it's either better / same / worse.
A few years ago she did something silly, she sat on the floor, I think we had been drinking. "Sweetie, you have to come down here and listen". I plopped my butt onto the floor, and wham, everything sounded better. Cohesive is the word I'll use.
My next build had recessed tweeter and midrange. The tweeter ever so slightly behind the midrange. The midrange just over an inch behind the midwoofer.
That is the speaker my wife and I listen to.
Are there diffraction issues with the step, yes. Does the overall cohesiveness of the speaker outweigh the diffraction issue, yes.
Listen to your speakers. Now move your head lower and lower. Is there a point where it sounds better? If it doesn't, then you don't need to time align anything. If it sounds better with your head slightly lower, then either tilt your speakers upwards, therefore moving the tweeter further from your ears, or build a time aligned box.
You experiment with time alignment AFTER the crossover is finished.
If you'd like to argue with my Italian wife, I'll put her on the computer. God help us all.
The only perfect speaker I've ever listened to was the Quad 57.
A few years ago she did something silly, she sat on the floor, I think we had been drinking. "Sweetie, you have to come down here and listen". I plopped my butt onto the floor, and wham, everything sounded better. Cohesive is the word I'll use.
My next build had recessed tweeter and midrange. The tweeter ever so slightly behind the midrange. The midrange just over an inch behind the midwoofer.
That is the speaker my wife and I listen to.
Are there diffraction issues with the step, yes. Does the overall cohesiveness of the speaker outweigh the diffraction issue, yes.
Listen to your speakers. Now move your head lower and lower. Is there a point where it sounds better? If it doesn't, then you don't need to time align anything. If it sounds better with your head slightly lower, then either tilt your speakers upwards, therefore moving the tweeter further from your ears, or build a time aligned box.
You experiment with time alignment AFTER the crossover is finished.
If you'd like to argue with my Italian wife, I'll put her on the computer. God help us all.
The only perfect speaker I've ever listened to was the Quad 57.
I had a similar experience standing up, wideband speakers,so no xover, it appears to be a "listening off axis" effect in my case
The last speaker that I built was a 3way with a sloped baffle. The angle and driver placement was such as to minimize the differences in their acoustic centers at a specific listening distance/height. I was able to get pretty close, but it was optimized for that one reasonable listening location. It turned out to be a vert coherent speaker that sounds a lot like a single driver full range without the shortcomings. Just needed to build a spreadsheet to do the trig. Still my favorite.
Paul
Paul
Hi Cousin Billy!
Yes, I have the same issue, but no wife to tell me I was wrong.
I design 2-ways on the tweeter axis but find sitting in front of the mid-woofer sounds a lot better. I have been blaming it up to a better tonal balance though, not really timing issues. Interesting that you achieve the desired effect by listening on-tweeter axis with a recess though.
Best,
E
Yes, I have the same issue, but no wife to tell me I was wrong.
I design 2-ways on the tweeter axis but find sitting in front of the mid-woofer sounds a lot better.
I have been blaming it up to a better tonal balance though, not really timing issues. Interesting that you achieve the desired effect by listening on-tweeter axis with a recess though. Best,
E
And here is where things get a little weird. Due to the introduction of most crossover filters, even if you attempt to push the tweeter back to 0 acoustic offset, your impulse response is not necessarily going to align. This is why I included a link to an XSim file. Try changing the woofer to 0 distance, and you'll see that the filters will still add enough group delay to keep the step from merging fully.
I mean, yes, fully time aligned speakers are difficult, I know. I'm just pointing out that Troels' designs with a stepped baffle are not time co-incident. This is why learning he's attempting an LR2, and adjusting the baffle to match explains his work.
Best,
E
I mean, yes, fully time aligned speakers are difficult, I know. I'm just pointing out that Troels' designs with a stepped baffle are not time co-incident. This is why learning he's attempting an LR2, and adjusting the baffle to match explains his work.
Best,
E
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