Good pictures, seems quite interesting. How does the whole membrane and it's support and phase plug sound when knocked with a fingernail?
I'm slightly surprised there is no shorting ring, maybe it's the high flux that saturates the motor's steels so deeply (like field coil drivers) so that the inductance is very low without extra shorting. I would have quessed there is either a shorting ring or neodymium slug inside the voice coil (dual magnets which act as a shorting ring) or both.
The phase plug's small slots seem to be (hard to tell from the picture though) adequately distanced from the diapgragm and those "separator air vents" separate the membrane from the top plate somewhat, so the membrane might be capable of some kind of xmax beyond the physical +/- 0,2mm of the underhung motor's vc/top plate thickness difference.
I'm slightly surprised there is no shorting ring, maybe it's the high flux that saturates the motor's steels so deeply (like field coil drivers) so that the inductance is very low without extra shorting. I would have quessed there is either a shorting ring or neodymium slug inside the voice coil (dual magnets which act as a shorting ring) or both.
The phase plug's small slots seem to be (hard to tell from the picture though) adequately distanced from the diapgragm and those "separator air vents" separate the membrane from the top plate somewhat, so the membrane might be capable of some kind of xmax beyond the physical +/- 0,2mm of the underhung motor's vc/top plate thickness difference.
That (to lower Fs) and maybe venting the pressure away from under the ring also lowers H2 and lessens the bending of the ring from pressure.
Ps. I'm quite eager to receive my pair
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Also Mabat, when you measure the impedance of hf1440, please post a graph with a small scale (like 0-30ohm) up until 40khz. In faital's graph there seems to be no evidence of breakup in impedance below 20khz, or it's so small it's not visible after smoothing. Curious to see what happens after 20khz, does the response fall asap or is there a break-up mode up in the uhf and how high does the response go before falling like a rock.
The impedance - as I said, I still don't have the horns for them (will make my own), so this is the best what I can provide at the moment - raw drivers just sitting on the table (tried various damping over the exit but it makes a negligible diffference above 10 kHz).
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On a comparative basis the discounted 306 euros is a good deal for the driver. (..the 450 euros - not a good deal.)
..again, it's begging for a 1st order design a bit below 2 kHz with the right horn IMO. (..where most would likely envision this driver pushed much lower with a steep high-pass.)
..again, it's begging for a 1st order design a bit below 2 kHz with the right horn IMO. (..where most would likely envision this driver pushed much lower with a steep high-pass.)
Does anyone have an opinion regarding the best 1,4" to 2" adapter for the HF1440 driver to be bolted to Yuichi A-290 horn?
For example, I calculated that in 18Sound adapter the flare rate is 11,5deg conical (37mm thick, 1,4" --> 2").
Now the Yuichi A-290 horn is "optimized" for TD-4001's internal flare rate. What I was able to find was that in TD-4001 the internal flare rate of the driver is closer to 5,5-6deg conical (64,5mm long path and from 1,5" to 2").
Should I be looking for a longer adapter because the Yuichi is optimized for Tad? Or would some faster flare rate be better for the Faital's radial phase plug design? What I understand that in Faital there is no "internal flare rate" and the driver is (acoustically) more like a pancake driver. Or is it... Who the hell knows this stuff
18sound adapter looks solid and has nice felt pads etc. quality stuff and looks tempting otherwise. Also there is not that much of an alternatives in the market and many do not state the exact lenght of the adapter. Should I tell my carpenter to make a ~55-60mm long wooden adapter
For example, I calculated that in 18Sound adapter the flare rate is 11,5deg conical (37mm thick, 1,4" --> 2").
Now the Yuichi A-290 horn is "optimized" for TD-4001's internal flare rate. What I was able to find was that in TD-4001 the internal flare rate of the driver is closer to 5,5-6deg conical (64,5mm long path and from 1,5" to 2").
Should I be looking for a longer adapter because the Yuichi is optimized for Tad? Or would some faster flare rate be better for the Faital's radial phase plug design? What I understand that in Faital there is no "internal flare rate" and the driver is (acoustically) more like a pancake driver. Or is it... Who the hell knows this stuff
18sound adapter looks solid and has nice felt pads etc. quality stuff and looks tempting otherwise. Also there is not that much of an alternatives in the market and many do not state the exact lenght of the adapter. Should I tell my carpenter to make a ~55-60mm long wooden adapter
Yuichi is rumored to be better than th-4001 horn. Although very similar, the Yuichi has slightly better throat design and vertical flare on the "lips" (it has straight and curvy parts on the lips), thats why it outperforms the th4001 sounding more natural and even on- and off axis.
High freqs are no problem for this horn. TD-4001 sounds very good in the Usher horn (which is closer to Yuichi than TH4001) and produces almost ruler flat response 400hz-20khz 0deg without xo.
It is to be seen how the hf1440 works in Yuichi horn, I presume the hf has much more downward slope than with td4001. And I'm positively surprised if not as much as I fear. Less than 10db diff. at 20khz and I'm positively surprised, but might be more.
The low end bandwidth and the point where the H3 starts to rise is another question mark, I hope it's good to around 600-800hz. The high ohmic value low impedance peak around 500-600hz scares me a little, telling that the driver is not mechanically very damped. Don't get me wrong, it's basically a good thing, but it turns to a bad thing if this also accentuates the H3 rise near the Fs and there might be a nasty H3 peak if the driver does not get much electrical damping (ie. low loopback impedance from positive to negative binding post of the driver). This only harasses in passive xo systems, in active systems and voltage source amps the electrical damping is always there (if not hindered on purpose by current driving the driver etc) .
For example Truextent beryllium diaphragms had nasty H3 peak near the Fs (passive, low xo point) unless you offered them electrical damping through the crossover, ie put a short circuiting coil as the last xo component, not series cap as the last. Tad TD-4001 does not suffer from high loopback nor high source impedance, H3 is controlled. HF1440 might suffer from it.
Xsim has a function how to check the loopback impedance if needed.
High freqs are no problem for this horn. TD-4001 sounds very good in the Usher horn (which is closer to Yuichi than TH4001) and produces almost ruler flat response 400hz-20khz 0deg without xo.
It is to be seen how the hf1440 works in Yuichi horn, I presume the hf has much more downward slope than with td4001. And I'm positively surprised if not as much as I fear. Less than 10db diff. at 20khz and I'm positively surprised, but might be more.
The low end bandwidth and the point where the H3 starts to rise is another question mark, I hope it's good to around 600-800hz. The high ohmic value low impedance peak around 500-600hz scares me a little, telling that the driver is not mechanically very damped. Don't get me wrong, it's basically a good thing, but it turns to a bad thing if this also accentuates the H3 rise near the Fs and there might be a nasty H3 peak if the driver does not get much electrical damping (ie. low loopback impedance from positive to negative binding post of the driver). This only harasses in passive xo systems, in active systems and voltage source amps the electrical damping is always there (if not hindered on purpose by current driving the driver etc) .
For example Truextent beryllium diaphragms had nasty H3 peak near the Fs (passive, low xo point) unless you offered them electrical damping through the crossover, ie put a short circuiting coil as the last xo component, not series cap as the last. Tad TD-4001 does not suffer from high loopback nor high source impedance, H3 is controlled. HF1440 might suffer from it.
Xsim has a function how to check the loopback impedance if needed.
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Thank you Legis for that inputt,
I follow your adventure guys to see if a 2 ways is doable while keeping some efficienty >= 95 dB after passive or active correction. I am attracted by correction made by the shape of front bafle and horn flare to avoid the much possible DSP or passive filter correction with LCR, LC, LR...(while it doesn't harm too much for passive parts as inputed Mabat)!
Edit :which sucks with DSP plate amp and time correction is the delay is set on the high pass filter so the horn above the bass driver and it means DAC to ADC to DAC towards Horn & compression driver or classic LP to ADC to DAC towards horn/compression driver ! Am I correct and so should such plate amp be avoid for keeping the best of SET or Path type amps ?
I follow your adventure guys to see if a 2 ways is doable while keeping some efficienty >= 95 dB after passive or active correction. I am attracted by correction made by the shape of front bafle and horn flare to avoid the much possible DSP or passive filter correction with LCR, LC, LR...(while it doesn't harm too much for passive parts as inputed Mabat)!
Edit :which sucks with DSP plate amp and time correction is the delay is set on the high pass filter so the horn above the bass driver and it means DAC to ADC to DAC towards Horn & compression driver or classic LP to ADC to DAC towards horn/compression driver ! Am I correct and so should such plate amp be avoid for keeping the best of SET or Path type amps ?
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Now I'm confused - you have in your signature "Life is too short to listen to average hifi" and then you mention Yuichi horns? 
And of course that with passive crossovers the impedance of the driver must be compensated for (or made other use of it), that's just the routine of crossover design.
And of course that with passive crossovers the impedance of the driver must be compensated for (or made other use of it), that's just the routine of crossover design.
I have had some drivers and horns including two 1" throat OS's, but td-4001 and Yuichi-family horn is the best kombo by quite a margin to my preference in current state of experience. Such a clarity, transient snap and life-likeness and timbral correctness compared to others I have owned. Truextent 4" be-diaphragms in Jbl frames don't come close for me, had them before tad.
Good learning exp. for me as I have never heard any other driver in such a horn (Yuichi). If I'm able to get the Faital to bring the goods like Tad in the same horn I'm one happy camper and richer also.
Good learning exp. for me as I have never heard any other driver in such a horn (Yuichi). If I'm able to get the Faital to bring the goods like Tad in the same horn I'm one happy camper and richer also
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