a quite long article that ends up with a mini-review of these the PMD"Most acoustically advanced audiophile loudspeaker available on earth today"
https://www.tektondesign.com/ulfberht-pmd-monitor.html
Probably not an English or American company and maybe Haberdasher means something different for them?Haberdasher??
Why would anyone name a speaker after clothing / sewing / hat retailer?
MeroVinger released the Haberdasher Mk. II, I don't know how to read directivity graphs, but the frequency response seems nice to me. If anyone could interpret the results I'd be very interested.
Thank you, now I know how to interpret the widening/narrowing @ the 2.5 kHz mark. Do you think this is very noticable, or could this still be a good loudspeaker for the money? I think I am going to try to audition these loudspeakers after I'm fully vaccinated.It has some directivity errors in the horizontal plane (compare @+/- 60° 1.5 kHz vs. 2.5 kHz (almost 6 dB). Also they could have done better in the vertical plane since it's a 3-way design (errors in the crossing area @2,5 kHz). Overall it seems to be a fairly conventional design which has not been optimized for constant directivity. That's a pity because having 3-ways and especially a small midrange driver, that could have been easily achieved...
While gradient doesn't show any measurements themselves, their excellence has been shown in third-party measurements. See for example stereophile's measurements of the original gradient revolution (an amazing feat of engineering more than 20 years ago).What evidence does Gradient provide that their designs are evidence-based?
Also, amir's review of the Kali IN-8 doesn't look like an evidence-based design to me... unless they attempted to be evidence-based, but failed.
Probably not an English or American company and maybe Haberdasher means something different for them?
The impedance of a passive loudspeaker can also be relatively easily equalised using passive components. The well-known Zobel network added to the tweeter serves to linearise a multi-way loudspeaker's high-frequency impedance quite well. Using a conjugate impedance network on the typical impedance hump that occurs around a crossover frequency is certainly not difficult either. Using a program like VituixCAD, one could easily come up with a suitable design, making a passive loudspeaker's impedance quite flat from 100 Hz or so upwards. This would essentially make that portion of the loudspeaker's impedance behave like a purely resistive load, albeit a lower impedance because the peaks and rising impedance responses have been equalised to now be flat.Output impedance profile (part of which can be realized with passive components after the amp, eg. series caps and coils) is a powerful additional degree of freedom available in active designs that should be exploited, alas only few manufacturers currently do this (though some don't advertise these features because the actual circuit designers implement this silenty... like I did in the ADAM F-Series).
Creating a suitable conjugate impedance network and adding it to a typical passive multi-way loudspeaker system would certainly affect the sound produced by the loudspeaker when driven by low-damping factor amplifiers, such as tube amplifiers.
As for creating conjugate impedance networks for the twin low-frequency peaks of a vented system, or the single low-frequency peak of a sealed enclosure, although that's entirely possible, it might not be all that economical, owing to the large component values that would be needed. The results might also be sensitive to driver variations from one enclosure to the next.
This approach appears to be an excellent solution to the age-old problem of metal tweeters, which have pronounced, very high-Q resonances at higher frequencies in their passband. The use of the titanium sandwich membrane appears to be a good example of the application of constrained layer damping technology, which is discussed by Kumar and Behera (2019). An early reference to this technique was the journal paper by Kerwin (1959), Damping of Flexural Waves by a Constrained Viscoelastic Layer, so the method has been around for a long time. It would be interesting to see the raw frequency response of the tweeter used in the KH-series, so that we could better assess the efficacy of the damping system that's been added to the titanium dome.From https://en-de.neumann.com/product_files/1710/download:
"The 1” tweeter will become the new standard for all new monitors in the KH-series by Neumann. ... The final choice was a titanium sandwich cone. Developer Markus Wolff told us that the decision in favour of a metal cone instead of a pure fabric membrane was based on the significantly more pistonic motion of the metal cone. This usually comes with the disadvantage of a pronounced resonance, but this is above 30 kHz and in this case very well damped. Actually a resonance in this frequency range way above the audible spectrum would not be a problem anyhow. But if the resonance is started, it could lead to intermodulation distortion even within the audible frequency range, which makes suppression of the resonance worthwhile. A pure fabric tweeter cone does not have this problem, but would vibrate unevenly way below 20 kHz and therefore would lead to an uncontrollable dispersion behaviour."
How might that be done? Would it require adding considerable losses into the enclosure design?Equalizing the upper impedance peak can even be accomplished at the enclosure design stage...
One would certainly hope not! Undesirable port resonances are the bane of many a vented box loudspeaker, and any designer would try and avoid them at all costs. The ideal port simply produces a peak at its resonance, with the port's output rolling off smoothly and monotonically above and below the resonance frequency.The measured vertical polar you describe above is just the result of non-concentric drivers through the crossover. The port isn't doing anything at 1–2 kHz.
How might that be done? Would it require adding considerable losses into the enclosure design?
Can you elaborate on that a bit more? I thought the shape of box does not change the tuning, but the volume does?The enclosure's internal shape targets the desired frequency region.
Can you elaborate on that a bit more?