Best get busy then. When you’re done with your peer reviewed study let us all know and we can review the white paper.
No problem. Yes top is genuine BASF Basotech. Not sure if the generic Chinese melamine foam matches the performance or not. The bottom chart is 6 different samples of 3D printed aerogel. Each using a different grain structure, and manufactured using different methods.
You guys are talking about baffle diffraction mitigation for tweeters, how important is it for the PTT6.5? I have used Scotchbrite pads around my full range midtweeter before. It does clean up some of the ripples.
It can help a lot with lobing. Especially if the tweeter is recessed for time alignment. It also helps when you have a wide baffle.
Preventing lobing is actually the main reason why everyone uses it, i just don't see any reason to use it on the sides of transducer.
@xrk971 You have to measure off-axis to see the real effects - but You probably know about it.
@Amplifier dude As for previous posts - You don't have to take it as offence, we just point that claims should be based on something that can be proven. My take in this case is that felt must be working well as everyone is using it (and I myself never measured anything in the matter so i don't know much).
The wider you make your baffle, the more it helps. What differences are seen when you double a baffle width without any baffle treatment?
I base what I do on what I discover on my own. Not based on what everyone else is doing. If everyone else was doing what I want to do already, there would be no point of me doing it. That market need would already be fulfilled.
Yes some things can work well, but it’s also possible for things to work better than just well. Since this is a DIY forum, some things might require some degree of “doing it yourself” to see the results. Because everyone has different design goals, as well as budget to work with.
I base what I do on what I discover on my own. Not based on what everyone else is doing. If everyone else was doing what I want to do already, there would be no point of me doing it. That market need would already be fulfilled.
Yes some things can work well, but it’s also possible for things to work better than just well. Since this is a DIY forum, some things might require some degree of “doing it yourself” to see the results. Because everyone has different design goals, as well as budget to work with.
Seems most forum based speaker builders worship at the alter of the heads of the Harman marketing department. Sean Olive, and Floyd Toole. If I wanted to target a certain sector of the market I’d hire them as marketing consultants as well.
Super sound scrubbers.
I don’t think it needs to be a sound absorber to work for diffraction control. It just needs to serve as an impedance matching interface. Think of it as an anti reflection coating used on optics but in the acoustic domain.
Look at the sawtooth edge they often put on the felt around the tweeter. That’s to gradually impose the impedance matching.
John Dunlavy’s original baffle diffraction patent. Very informative read.
https://patents.google.com/patent/US4167985A/en
https://patents.google.com/patent/US4167985A/en
You Mean Dr Sean Olive and Dr Floyd Toole? Calling them the 'marketing department' is disingenuous. And can we get back to Purifi woofers at some point?
Different approach. But great sounding. And makes the speaker much more room friendly. Great interview with the man.
https://www.stereophile.com/interviews/163/index.html
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They do a great job at marketing. I’ll give them that. So good, people don’t realize their true role at Harman. Yes please share your build.
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Yeah, back to Purifi woofers.
Troel has a new build. 2x 6.5W for the woofer + 1x 6.5M for midrange + TW29BN for the tweeter duties.
http://www.troelsgravesen.dk/Purifi-6661.htm
That's close to US$3000 on drivers alone!
Troel has a new build. 2x 6.5W for the woofer + 1x 6.5M for midrange + TW29BN for the tweeter duties.
http://www.troelsgravesen.dk/Purifi-6661.htm
That's close to US$3000 on drivers alone!
From that interview, I see that I have also been designing speakers based on what Dunlavy said: ”It may come as a surprise—this is giving away a trade secret—but when I design a loudspeaker, I first design it by looking at the step response. I find that by playing around with the crossover network while observing the step response in real time, any change I make is immediately available. When I get the step response right, everything else goes along. It's implicit. It goes along for the ride.”
I have always considered the step response most important, hence I have worked on transient perfect crossovers using the Harsch XO (normally used in DSP) in a passive manner, such as what I did with my PTT6.5 build. So getting back to the PTT6.5…
https://www.diyaudio.com/community/...using-ptt6-5-and-rs28f-in-a-waveguide.354778/
Here is my step response:
Complete CAD plans, 3D print file for waveguide adapter, and all details to build this TL speaker in the above thread. RS28F can be replaced with RST28F.
Cheers,
X
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Troels tells this in his PPT6661 page http://www.troelsgravesen.dk/Purifi-6661.htm
"Every graph needs interpretation in terms of what it means sonically and how it impacts our choice of mating drivers, cabinet and crossover design. What measurements certainly do not tell is the sonic signature of the speaker, because speaker cones made from polypropylene, aluminum, Kevlar, paper, glass fiber, carbon fiber, magnesium, ceramics or even diamonds all have their way of adding spices to the stew. Nor do measurements tell what impact the quality of the crossover components add to the sound, from state of the art components to the cheapest of coils and caps, they all measure the same if values are correct, yet sound very different."
Then I must be half-deaf...
And why not to use 2ch amp and highpass for the mid?
http://www.troelsgravesen.dk/Purifi-6661/Purifi-6661_xover_v7_no-values.png
"Every graph needs interpretation in terms of what it means sonically and how it impacts our choice of mating drivers, cabinet and crossover design. What measurements certainly do not tell is the sonic signature of the speaker, because speaker cones made from polypropylene, aluminum, Kevlar, paper, glass fiber, carbon fiber, magnesium, ceramics or even diamonds all have their way of adding spices to the stew. Nor do measurements tell what impact the quality of the crossover components add to the sound, from state of the art components to the cheapest of coils and caps, they all measure the same if values are correct, yet sound very different."
Then I must be half-deaf...
And why not to use 2ch amp and highpass for the mid?
http://www.troelsgravesen.dk/Purifi-6661/Purifi-6661_xover_v7_no-values.png
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One thing he’s wrong on is that passive crossover components that sound different, all measure the same. Yes maybe if you’re measuring with a microphone from the drivers. But if you measure directly from the crossover with an audio analyzer, you can clearly measure differences between poor and good quality passive crossover parts.
This is why I prefer a solid piece of OCC copper in place of passive crossover components. Because even the finest performing passive crossover parts are a major compromise When placed between the amplifier and speaker drivers.
Try to get a measurement like this out of a Purifi 1ET400A module with a Revel Salon 2 crossover in the signal path: