I can probably look into this. I believe the Powersoft DSP can send clock information over ethernet or AES/EBU and sync the clocks of multiple DSPs together. We're definitely not the first ones to realize the problems of clock drift.
I am open to share ideas, it is always a good thing to have some brainstorming with someone with similar interests. I was actually interested in the Danville DSP modules and their standalone processor, but they are not responding to my e-mails at all, i have sent them around 4 and given up, perhaps mails from Czech republic go into spam.. .
I was warking with Pascal amps few years ago, using the AllDSP plate amps, and it was not bad at all, but personally i would use them now only for the sub-bass section of active speakers, Hypex Ncore modules sounded somehow better to me, and i think that they also have much better parameters. Could you perhaps tell me what are the OEM prices for their Snowbird, Greywolf DSPs and DSP Nexus processor? If you have contacted somebody there, would you please share the contact? Thanks!
Yes by using an AES67 compliant interface it’s possible. But who makes one with video sync and a THD+N like this?
Man we have been down all the same roads. None of those solutions met my requirements. Which is why I developed the system that I did. Shoot me a PM if you want to talk offline about things. I don’t want to dominate this thread with DSP talk.
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Adam thanks.
Nice marriage btw: the Purify and the DXT.
Am I correct in spotting a reinforcement/stabilizing ring, just like the paper coned version has, at outside of the cone? @Lars: is my observation right?
Never would have assumed that technique would work with aluminium cones as well.
Nice marriage btw: the Purify and the DXT.
Am I correct in spotting a reinforcement/stabilizing ring, just like the paper coned version has, at outside of the cone? @Lars: is my observation right?
Never would have assumed that technique would work with aluminium cones as well.
VituixCAD let’s you know the SPL at the maximum excursion level, at any given power level. And allows you to implement the DSP curve as well. So you don’t need to go with general theory based on the average woofer.
With the Purifi 6.5, about 3 more dB is possible from the woofers in 4l vs 7l. Yes it takes more power to get there, but I have 450W at my disposal. So the optimum volume for me is the volume that gets me the maximum SPL at the target F3, without exceeding the thermal limits of the voice coil, or bottoming out the woofer.
Another bonus is the smaller the cabinet is, the more rigid it is with the same material thickness. Also making a smaller speaker is attractive for the 99.9% of the population who is far more into music than audio gear.
So I redid my modeling. And I was off on my previously quoted SPL figures. It must have been for the max excursion. Not 12mm. It was like a year ago so forgot. Anyways I did it again for an F3 of 30hz, at 12mm excursion, in a cabinet volume of 4L, 7L and 12L. Results for each below. Which volume allows us to get the most from that powerful motor system?
4L:
7L:
12L:
4L:
7L:
12L:
You do not get anymore maximum SPL from a larger sealed cabinet as long as the power limit isn't exceeded. In a sealed cabinet, the SPL is purely determined by the displacement of the driver. What you do get is greater bass efficiency from a larger cabinet. Using a smaller cabinet will get you a higher F3, but it can be compensated by DSP. In a 4L cabinet the Purifi woofer can hit its Xmax without exceeding its power limit. Therefore, the maximum SPL in a 4L cabinet is exactly the same as a 7L cabinet. It just takes more power and more DSP boost for the same SPL and F3.
Also, on an earlier post you mentioned you get free 6dB boost from an in wall install. This is incorrect as well. Most modelling software default to half space for simulations rather than full space. Therefore this is exactly the same results as an in wall. Compared to a stand mount speaker, which is radiating in full space, you still do not get 6dB boost in the low end from an in wall install. For low frequencies simply being near a wall is good enough to get close to the full 6dB coupling gain per boundary because it is within 1/4 wavelength distance of the boundary. The real efficiency gain from an in wall vs a stand mount is in the lower midrange, where a stand mount is not within 1/4 wavelength distance of the boundary walls and do not couple efficiently.
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Standard speaker frequency response ratings are anechoic full space measurements. Since an in-wall speaker is always built into the wall, you can assure a half space response in all use cases.
If you try to place a rear ported, or rear passive radiator speaker right against the wall to achieve close to a half space response, the results won’t be very good.
If you try to place a rear ported, or rear passive radiator speaker right against the wall to achieve close to a half space response, the results won’t be very good.
There are some basic rules of physics (acoustics) and that you are, lacking careful attention to.
As @bcodemz said; at bass frequencies what determines the maximum SPL is the displaced volume of air (emissive surface area multiplied by excursion). at midrange frequencies what determines max SPL is voltage drive.
In Vituixcad Adude, if you edit the parameters of your driver eg. Increase Sd or more x-max; you will see that the max SPL in the bass frequencies goes up. If you increase the voltage drive whilst maiming the Sd and x-max you will see the SPL go up in the midrange frequencies.
I didn’t edit the parameters of the driver when I changed the cabinet volumes. Because the driver parameters don’t change if you put them into cabinets of different volume.
Either way you want to put it, 4L is the best volume for sealed for the below very important reasons:
1: The smaller the cabinet volume, the more rigid the cabinet is. For example a 4L cabinet with 1” thick MDF walls, is equivalent in cabinet inertness to a 12l cabinet with 3” walls. But very few 12l+ cabinets I see have 3” thick walls.
2: You can actually sell a speaker to the 99.9% of the consumer population. Because the size is small enough to not clutter up a room too much.
Either way you want to put it, 4L is the best volume for sealed for the below very important reasons:
1: The smaller the cabinet volume, the more rigid the cabinet is. For example a 4L cabinet with 1” thick MDF walls, is equivalent in cabinet inertness to a 12l cabinet with 3” walls. But very few 12l+ cabinets I see have 3” thick walls.
2: You can actually sell a speaker to the 99.9% of the consumer population. Because the size is small enough to not clutter up a room too much.
The driver parameter may not have changed, but the box changed, and therefore the lumped parameters of the box + driver has changed. This is why the excursion is different, and why the response shape is different depending on the box volume. If you normalize for excursion, you'll see the SPL is exactly the same for a given amount of excursion and frequency no matter the box size.
This is definitely not true. You can easily see this through your own example. Take a 100L subwoofer box built with 1" MDF, which is very common. By your logic this is the same as a 4L cabinet with 1/25" walls, or 1mm thick walls. Clearly that's not the case.
Stiffness is the product of the material modulus of elasticity and the section moment of inertia. For a rectangular cross section, the moment of inertia is (wh^3)/12, where w is width and h is depth. The important part to note is that the relationship between stiffness and thickness is cubic, meaning if you double the thickness, the stiffness increases by a factor of 8. If you triple the thickness, the stiffness increases by a factor of 64.
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That’s about 11.8mm and the 4l is 12mm. Would have made about a 0.2dB difference in spl if I added the tiny bit more power to hit 12mm.