Very nice! I’m doing similar in walls, but 100% active. Baffle from 1 design with Bliesma tweeter. 6l sealed on the midwoofer running 120hz up, and each lower woofer is in it’s own 4l sealed sub-enclosure. 6dB free boost in the low end with in wall. And I can run the bag off the woofers without adding any distortion to the mid. All Purifi amplification driving each driver direct.
Also very nice!
I have my eye on the Bliesma tweeters, planing to test them soon. My setup is actually also fully active, but i have built custom amps with Hypex MP modules and Hypex DSP modules. Have a look:
Awesome. We do similar things. I make DSP amp units with Ravenna AES67 inputs and Purifi amps. They build into the walls under the speakers. And I use fibre optic Ethernet from the new Ravenna options in the Trinnov or Storm Audio processors to the speakers. Rather than speaker wires. Here’s the full system 1w/1khz THD+N into 4R load. With a test tone sent from Roon. From there direct to the drivers over a couple ft of speaker cables. Can clock sync up to 128 amps on a 1g Ethernet network.
Course you do the QTC changes F3 changes whenever you change the sealed cabinet volume. You can compensate for it with EQ and drive it with more volts
And drive up the distortion.
Whether it’s appreciable or acceptable or not is a trade-off you decide on as a designer
And drive up the distortion.
Whether it’s appreciable or acceptable or not is a trade-off you decide on as a designer
But this driver is designed for this. You can’t achieve the performance that this driver was designed to achieve in a volume bigger than 4L. Based on my modelling anyways. You end up bottoming out long before the voice coil starts to warm up.
I know it’s just a simulator.
Some are more accurate that others.
measure and validate and see for yourself they’ll be changes that may be measurable but not audible or audible but not yet measureable.
Some are more accurate that others.
measure and validate and see for yourself they’ll be changes that may be measurable but not audible or audible but not yet measureable.
Wow, that looks very good! perhaps we are doing the same thing! Could you also share some pics of the install? Are you using the same midwoofers as me? I had some info that they will work best in sealed enclosure of 12 liters, have you also tried or simulated bigger volumes? If 4 liters is enough, that is a great news. What is the F3 of the PTT6.5 in 4 liters? We can join forces sometimes! 🙂 I am also looking for DSP alternatives with ethernet signal distribution and ethernet online controls.. Can i ask which DSP modules you are using? The Hypex DSP is cheap, and their amps are great value for money, but the HFD software is terrible to work with, and it stays terrible for all the 10 years that i am working with Hypex, no real progress or innovation in all those years. So far i have bought also some DSP samples with ethernet from Four Audio, those were the most expensive, but did not have time to test them. Also i am testing now some Powersoft DSP Lite modules with their power amp modules, and those are very promising, the Harmonia software is like from the future compared to Hypex Filter Design..
I’m starting that process this week. Comparing my friends 7l volume speakers with my 4l volume speakers.
My DSP/DAC system is an in house design. Can’t find this for sale. Several years in the works. I have no install pictures. I’ve just perfected the electronics, and just messing around with speakers.
According to simulations with the 6.5’s the F3 is 30hz with an SPL of 95dB per driver, or 100dB with an F3 of 40hz, to reach 12mm excursion. In a 4L sealed volume with the proper DSP boost. Then you can add the extra 6dB of free boost you get building in wall.
Ok, the inhouse DSP-DAC system sounds interesting! I was obviously asking about F3 without boost..
Yes it sure is. Started on it in 2015. Finally ready. Well boost is the only way to go when you have DSP and a sealed cabinet. Unless of course you don’t have woofers with a beefy 4 layer voice coil designed for boost in small sealed cabinets.
Comments from @lrisbo on his recommendations with this 6.5” woofer. Perhaps he can chime in with a refresher 🙂
"It all depends on performance and cost objectives of course. For highest quality (but not the loudest) I would go for sealed and DSP EQ and excursion limitation. Preferably adding a third woofer e.g. on the back - could be rolled off with and LP filter at say 100Hz to serve as a sub assist. Could also do some directivity control.
A PR system has a fifth order highpass transfer function including a deep null at the PR free field resonance (17Hz for the 80g version). This null is very hard to EQ (borderline non minimum phase and the woofer and PR are completely out of phase here) so it’s difficult to get very deep bass extension. A sealed box is a simpler 2nd order high pass that can be EQed down to any frequency (with a proper excursion limited). Personally, I prefer an EQ to a 2nd order high pass at 20Hz with Q=0.5 ie critical damping aka aperiodic. The EQ filter necessary is a 2nd order shelving filter often called a Linkwitz (named after Siegfried Linkwitz co inventor of the LR crosover filters)
The advantage of a PR (or port ) is that the excursion to SPL efficiency of the woofer is increased (acts like extra cone area) but only just around the tuning frequency and below excursion explodes."
"It all depends on performance and cost objectives of course. For highest quality (but not the loudest) I would go for sealed and DSP EQ and excursion limitation. Preferably adding a third woofer e.g. on the back - could be rolled off with and LP filter at say 100Hz to serve as a sub assist. Could also do some directivity control.
A PR system has a fifth order highpass transfer function including a deep null at the PR free field resonance (17Hz for the 80g version). This null is very hard to EQ (borderline non minimum phase and the woofer and PR are completely out of phase here) so it’s difficult to get very deep bass extension. A sealed box is a simpler 2nd order high pass that can be EQed down to any frequency (with a proper excursion limited). Personally, I prefer an EQ to a 2nd order high pass at 20Hz with Q=0.5 ie critical damping aka aperiodic. The EQ filter necessary is a 2nd order shelving filter often called a Linkwitz (named after Siegfried Linkwitz co inventor of the LR crosover filters)
The advantage of a PR (or port ) is that the excursion to SPL efficiency of the woofer is increased (acts like extra cone area) but only just around the tuning frequency and below excursion explodes."
And that cabinet is only that big because of the electronics sub-enclosure. I built these to mount on flatscreen TV stands for testing.
View from the front. The 1” stacked layers of MDF glue together with this viscoelastic damping adhesive:
http://www.swedac-acoustic.com/products/stomljudsdampande/damplim-dg-a2/
http://www.swedac-acoustic.com/products/stomljudsdampande/damplim-dg-a2/
That's a very interesting DSP system you're working on there. I'm working on something very similar. I will be developing a very high power plate amp with either Powersoft or Danville DSP and Pascal L-Pro amplifiers for my build with 4x Purifi woofers. It could be interesting to join forces or at least bounce off ideas with you, as well as anyone else also interested.
Have you figured out a solution for clock sync between speakers, or perfect sync with video with no latency?
Clock sync is not high on my priority list given the enormous number of areas to work on the speaker and DSP algorithm side (look ahead limiters, smart equal loudness, ambiance processing, etc), but it's on the list. There are pro audio solutions for clock sync using AVB or some other networking protocol to achieve this, but I won't have it in my own plate amp
Perfect sync with video shouldn't be too hard. Generally the display is lagging behind the speaker because of video processing latency, so all that needs to be done is to measure the delay on the TV/projector side, and then add the appropriate delay on the DSP. Measuring the video delay is a bit tricky though, but definitely doable.
Clock sync between speakers is absolutely essential for high end audio. And absolutely essential for video sync. Even if you set a delay for timing, if the same master clock isn’t timing both the audio and video, it drifts over time. And you end up with a disaster within a few minutes.
These are some of the things I discovered 7 years ago when I was at your stage
These are some of the things I discovered 7 years ago when I was at your stage
Someone needs to chime in on how you can maintain clock sync between multiple endpoints when a SRC4392 is used on the inputs of all the SPDIF, or AES/EBU inputs of all modern audio gear.
https://www.ti.com/lit/ds/symlink/src4392.pdf
https://www.ti.com/lit/ds/symlink/src4392.pdf