Thanks, X 
It's a pretty weird recipe of multiple molding stages, material selection, vacuum, etc. and hand placement. Hand constructed with the aid of custom tooling, basically. Now that I have an idea of what the correct approach is, I'm confident I can achieve relatively complex and pristine parts. Hoping to see big improvements on the next attempts.
It's a pretty weird recipe of multiple molding stages, material selection, vacuum, etc. and hand placement. Hand constructed with the aid of custom tooling, basically. Now that I have an idea of what the correct approach is, I'm confident I can achieve relatively complex and pristine parts. Hoping to see big improvements on the next attempts.
Super cool. I'd be very interested in seeing progress pics or just more info in general - do you have a different thread or blog/etc?Thanks, X
It's a pretty weird recipe of multiple molding stages, material selection, vacuum, etc. and hand placement. Hand constructed with the aid of custom tooling, basically. Now that I have an idea of what the correct approach is, I'm confident I can achieve relatively complex and pristine parts. Hoping to see big improvements on the next attempts.
@mngnt, thanks-
No blog currently.
Created a thread on the iso panel progress here: https://www.diyaudio.com/forums/multi-way/375101-carbon-composite-panel-system.html#post6734617
No blog currently.
Created a thread on the iso panel progress here: https://www.diyaudio.com/forums/multi-way/375101-carbon-composite-panel-system.html#post6734617
PTT6.5X04-NFA-01 tested by Vance Dickason for AudioXpress Test Bench.
Test Bench: An Extended Home Audio 6.5” Midbass Transducer from Purifi Audio | audioXpress
Quoting the article:
"Figure 11 gives the inductance curve Le(X). Motor inductance will typically increase in the rear direction from the zero rest position as the voice coil covers more of the pole in a conventional motor, which is not exactly what you see in this graph. More important, the inductive “swing” from maximum inductance to minimum inductance from 10mm coil-in to 10mm coil-out gives a maximum inductive change of an almost nonexistent 0.009mH, which is nothing short of amazing and it is the lowest recorded inductive swing since Voice Coil started using the Klippel analyzer. Cheers to Purifi!"
Also a previously unseen image of the motor assembly and thoughtful discussion of its advanced design.
Test Bench: An Extended Home Audio 6.5” Midbass Transducer from Purifi Audio | audioXpress
Quoting the article:
"Figure 11 gives the inductance curve Le(X). Motor inductance will typically increase in the rear direction from the zero rest position as the voice coil covers more of the pole in a conventional motor, which is not exactly what you see in this graph. More important, the inductive “swing” from maximum inductance to minimum inductance from 10mm coil-in to 10mm coil-out gives a maximum inductive change of an almost nonexistent 0.009mH, which is nothing short of amazing and it is the lowest recorded inductive swing since Voice Coil started using the Klippel analyzer. Cheers to Purifi!"
Also a previously unseen image of the motor assembly and thoughtful discussion of its advanced design.
Hi IslandPink,
My measurements of the PTT6.5 and RS28F in a WG300 waveguide with the Harsch passive XO and TL yielded an average group delay of about 1.5milliseconds (I added a visual indicator straight line by eyeball to show the "average" value) at the 50Hz kickdrum frequency. It blows up at the corner tuning frequency circa 30Hz as expected as there is a round "knee" there and room modes dominate so it doesn't matter anyway. There are some wiggles and oscillations in the GD (+/- 2.5ms) due to a ripples in the frequency response. But the average group delay with 6 cycles FDW filtering to remove the effects of room modes. The number I like to look at is the difference between the GD at 100Hz and 1kHz. For this speaker, it is fairly low and indicates an excellent timing-accuracy between treble and bass.
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Simple Passive Harsch XO Using PTT6.5 and RS28F in a Waveguide
Basically as described in the plans: line main rear chamber with eggcrate foam and one side of the remaining TL with one side. No foam on the final path to the exit. Add poly fill stuffing from closed end to the first turn. Increase stuffing density to taste. Measure impedance sweep and look for point at which the double peaks straddling bass tuning frequency start to combine together to look like an single “horned owl’s head with two ears”. Adding reticulated fish aquarium filter foam (large pore size) at the terminus can also be used tune the impedance peaks. Use this sparingly as it is very sensitive here. Maybe 1/2in thick at most.
