Good Thinkin'
I like PR and sealed alignments AND baffleless.
Ports are nice but I find them tricky to get "just right."
6°c and cloudy in Minnesota
Lots of folks out walking (their dogs) and keeping their virus distance.
I like PR and sealed alignments AND baffleless.
Ports are nice but I find them tricky to get "just right."
6°c and cloudy in Minnesota
Lots of folks out walking (their dogs) and keeping their virus distance.
Use Basotect, great damping stuff !
After adding 5-10cm on the inner walls it removed the "booming" sound I had sometimes.
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Basotec is the brand name of a damping foam available in Europe. Compared to regular "Pryamidfoam", it has damping capability in lower frequency regions: If you would want to damp a room in bass-frequency-regions with it, you´d still be needing veeery thick plates. In an Bass enclosure, it is more useful to get rid of the mids reflecting inside the cab. Other foams will work for this, as well.
Not only mids, works great at lower freqencies too,
with 5-10cm basotect on the innerwalls it removed the unwanted peaks by 1db at 65-200hz and by 1-2db at 200-1000Hz.
Much less internal resonances.
Twaron is the damping material that also works at very low frequencies,
I had a combination of felt(1.5cm), Basotect(5-10cm) on the walls and some Twaron between (4g/l) but the Basotect with Twaron damped the bass cabinet too much.
Just felt and Basotect on the walls did it for me.
I use the Twaron in the mid cabinet (3g/l).
Here's a thread with measurements of different damping materials.
with 5-10cm basotect on the innerwalls it removed the unwanted peaks by 1db at 65-200hz and by 1-2db at 200-1000Hz.
Much less internal resonances.
Twaron is the damping material that also works at very low frequencies,
I had a combination of felt(1.5cm), Basotect(5-10cm) on the walls and some Twaron between (4g/l) but the Basotect with Twaron damped the bass cabinet too much.
Just felt and Basotect on the walls did it for me.
I use the Twaron in the mid cabinet (3g/l).
Here's a thread with measurements of different damping materials.
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The thicker the foam, the lower the frequencies you can damp out. To get into bass-regions (lets say below 100Hz) you´d need a veery thick layer of foam - even Basotec. If this weren't the case, room acoustic treatmen would be much easier and cheaper... Take a look at this chart from the manufacturer of Basotec:
As you mentioned, in a Bass cabinet, you don´t want to damp too much...
As you mentioned, in a Bass cabinet, you don´t want to damp too much...
Does this foam detract from the enclosure volume or does it make it virtually bigger as regular damping material?
I contacted them start of march , they expected to be testing samples end of march, but noted that c19 was hampering the work. One can only guess now that this driver is a long way behind schedule.
Others might have newer information.
Others might have newer information.
the latter, but I am not sure to what degree, since in the cases We used it, it was never about "enclosure tuning" but more for room treatment. I am not aware of a case where someone tried to use it in a bass-enclosure for reducing low-mids - really doesn't make much sense in my opinion. Thin sheets for dampening out mids at the outer cabinet walls are used sometimes - but in a ported enclosure, it probably would kill too much of the port-energy if filled up entirely with basotec.
For the technically inclined: Bruno just posted on the non-linear effects in cores, which he apparently has found a solution for. Hence the focus on class D (output inductors) and speaker drivers. Very nice presentation with animation:
This Thing We Have About Hysteresis Distortion - PURIFI
Jan
This Thing We Have About Hysteresis Distortion - PURIFI
Jan
Just noticed this in the Purifi website. A new 6.5" ? PTT6.5W08 (vs PTT6.5W04)
Looks like a 8 Ohm version with a higher Fs.
PTT6.5W08 - PURIFI
Looks like a 8 Ohm version with a higher Fs.
PTT6.5W08 - PURIFI
More PURIFI press. Spoiler alert, its another rave.
https://soundstagehifi.com/index.php/opinion/1420-purifi-audios-pint-sized-powerhouses
https://soundstagehifi.com/index.php/opinion/1420-purifi-audios-pint-sized-powerhouses
Anyone thought about adding a Morel TM4055 mid/tweeter to the Purifi 6.5 (Or two) crossing over at around 800hz?
Basotect is the brand name for reticulated (open cell) melamine foam from BASF.
Electron micrograph:
Since the patent expired, it has been made for much less and used as cleaning ("Magic Eraser") abrasive pads. You can get a bag of 100 pads (6cm x 10cm x 2cm ea) for under $10 from eBay/Aliexpress. I have been using this as the main absorptive material directly behind a driver in the rear chamber. It totally stops the boominess or echo like back reflections. Usually a single 2cm layer in line-of-sight of the driver membrane is all that is needed. Melamine is superior to polyurethane foam since the pore size is smaller and void fraction is very low. It is also fire proof and doesn't decompose into a stinky mess in 15 years like all polyurethanes eventually do. This stuff is a critical part of all my speaker builds now.
Basotect for damping BR-cabinet?!
For example:
100PCS Magic Nano Sponge Eraser Cleaning Multi-functional Foam Cleaner Tool set | eBay
Honeymoon continues. Swapping out my Soekris dam1941 DAC for my Cord Mojo revealed the bass is even deeper and stronger than I reported here:
[wiki=https://www.diyaudio.com/forums/multi-way/352063-exploring-purifi-woofer-speaker-builds-13.html#post6209421]%[/wiki]
The PTT6.5 is a midwoofer, not woofer. Yes, the SOTA bass is the first thing one hears but the long term pleasure comes from the PTT6.5's midrange magic. Morel makes excellent drivers but not taking advantage of the state of the art performance the PTT6.5 offers in the 100s to 3kHz range is spending more on a midrange driver and crossover parts to go backwards in sonics. Better to spend that budget on upgraded crossover parts and/or cabinet construction.
This article helps explain why I feel so strongly about this:
Distortion, The Sound That Dare Not Speak Its Name - PURIFI
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