The speaker was still on the bench.
Microphone was moved to about 1 yard to 1 meter away from the mouth of the STH100.
The microphone and analyzer set to auto calibrate to 2.5khz at 110dbB. See the attached plots.
Note increased distortion. Still not too bad.
Thanks DT
I helped dial-in a 950BePB on a K-402 horn using a DSP crossover, a Xilica XP series, a few years ago, remotely without the benefit of listening. IIRC it required about the same correction as my TAD TD-4002s which I've been running on my own K-402 horns since 2009.
The TADs beat the Celestion Axi2050 by a small margin, in terms of "sparkle" on the highest octave. While the Axi2050 will go one octave lower on a K-402 horn (~230 Hz, which can be useful), both the 950BePB and the TD-4002 cross comfortably on a K-402 at 475-550 Hz using first order filters for home hi-fi duty.
I would recommend the Radian 950BePB based on the above experience over other 2" compression drivers.
Chris
The TADs beat the Celestion Axi2050 by a small margin, in terms of "sparkle" on the highest octave. While the Axi2050 will go one octave lower on a K-402 horn (~230 Hz, which can be useful), both the 950BePB and the TD-4002 cross comfortably on a K-402 at 475-550 Hz using first order filters for home hi-fi duty.
I would recommend the Radian 950BePB based on the above experience over other 2" compression drivers.
Chris
Google nice italian site from dibirama...he has tested the 108r thd and amplitude as well.
It is not clear to me the R version is profitable from the non R version with its lower impedance ?!
Yes, if I were going to seek a system-level solution (i.e., loudspeakers, room acoustics, and electronics), I'd recommend bi-amped BMS 4592ND drivers on K-402 horns (or the equivalent sized dual flare straight-sided horns with rounded-over flare). This configuration requires an additional channel of amplification for each loudspeaker, which requires at least an additional stereo amplifier and associated cables, as well as extra output channels on the DSP crossover(s) to accommodate the added "way" in the BMS 4592ND drivers. This assumes a stereo system configuration. Note that I run a dialed-in 5.2 array for listening to high quality acoustic music (and most audible on multichannel SACDs that have been originally recorded since ~2001).
The reason why I'd go that way is 1) potentially lower overall cost, and 2) reducing FM distortion that might be audible when playing the system at high levels (i.e., the bandwidth of the higher frequency driver is broken into two parts to effectively eliminate FM [Doppler] distortion that is only audible at very high output SPL).
Chris
Thanks. So you like 950be better than TAD 4002?
Where can I get K-402 replica?
Btw someone mention that 2" exit driver has flaw by design. The throat is too big so it has resonance low in frequency and low constant directivity behavior?
Is this true? I would love to know everyone opinion.
I said that the 950BePB curved like a TD-4002. I haven't heard the 950BePB. If anyone here has heard it, I'd rely on their experience (hearing is believing).
The 950BePB having a beryllium dome diaphragm helps a lot, but witness the JBL drivers that have been retrofitted with Truextent diaphragms. The expected benefits of Beryllium (about 7x better in this application) just aren't there in that ratio--in my estimation.
You can't "get" a K-402 replica, but you can order a KPT-402-HF assembly from Klipsch. They cost about $1200 USD and have a modified BMS DE75 driver attached, and an adjustable base. That's as cheap as it gets to have a new K-402 horn, I'm afraid (their rules, not mine).
If low cost it that important to your project, I'd recommend using Bill Waslo's Synergy Calc spreadsheet. I've got a version of his spreadsheet with a K-402-like dual flare design already embedded in it. All you have to do is to cut the plywood and assemble, paying particular attention to the throat entrance geometry (i.e., making a square-to-round entrance plate). PM for details.
Chris
The issue with any driver exit diameter is related to dispersing the output above a frequency which corresponds to a half wavelength of sound across the throat exit--the sound above these frequencies "beam". For a 2" driver, that's ~6800 Hz at room temperature. For a 1" driver, it's ~13500 Hz, so both have issues, just at different frequencies.
There is a fix for this: an in-throat acoustic lens that divides the throat diameter into smaller annular distances:
In my subjective experience, this little 3D printed acoustic lens that slips in between the driver and the horn throat seems to solve that issue. I can now walk off axis at extreme angles to the K-402 centerline and the timbre of the sound doesn't change (i.e., above 6.8 kHz up to the limit of my hearing acuity--which probably is below 20 kHz at reasonable SPL).
This also creates a more realistic decay in-room while listening essentially on-axis. The extreme highs that are reflected off the walls, ceiling and floor sound like they should as if the real instruments or voices are playing in-person (subject to the limitations that the recording engineers placed on their recording via microphone choice and their placement, as well as in-line compression that's typically used).
Chris
Hi milezone, others, have you tried BMS 4544? Its less than half the price of 4552ND or 4550 but seems to be closely related, main specs are about the same and graphs look almost identical. Some aftermaket replacement diaphragms list all these drivers like this one https://www.artsound.gr/product/aftermarket-bms-4550-diaphragm-for-yorkville-7402/
Going after rumours, hard to resist cheap
There might be possibility to order pair of drivers and BMS annular diaphragm drivers are tempting as they are clearly different kind of driver than the HF10AK I have, price of 4544 is not too high either. Main difference seems to be distortion performance < 1kHz which doesn't look too big to me as its for home hifi.
