Has anyone ever considered diying a PWT and comparing the results with a driver tested by the manufacturer on a PWT in order to provide some validation? I suppose we would be talking about dedicated PWT for 1 inch, 1.4/1.5 inch and 2 inch drivers.
Build around something like the commonly available and inexpensive UMIK-1 mic and REW? Am I off base here?
A community funded project perhaps?
Build around something like the commonly available and inexpensive UMIK-1 mic and REW? Am I off base here?
A community funded project perhaps?
Basic PWT tubes are fairly cheap and are sufficiently good for measuring as long as you gate the measurement for the tube length. I have a 1inch and 2inch PWTs made this way. I wanted to use the PWT data in simulations for custom horns. PWT 1 inch
The problem is I need the data before I buy the driver. The mystery driver's surprises may be (or often not) on the upside however I'd be happier without the mystery.
Sorry, last TOP half-octave: 15kHz to 20 kHz.
It's very good for a large format driver (1.4" exit or larger), but not spectacular.
Note: a beryllium driver doesn't always result in an improved result (a good example of this is the recent Radian 1" exit driver on Test Bench magazine):
https://audioxpress.com/article/voi...udio-475bepb-8-1-beryllium-compression-driver
I agree that PWT data is valuable. I participated in a thread here in 2012 titled “Poor man’s plane wave tube”. I am not sure how to in-bed a link here. 🙁
I still have it and use it often.
Barry.
I still have it and use it often.
Barry.
Yet, all the reviews in that magazine ends with appreciation of the product on the bench. I don't think I have seen one single bad review from AX....
//
Hello All,
Again for fun.
This is the impedance plot for the FaitalPro HF108R 16R with the STH100 waveguide.
I like to cross these over at or above 2kHz, well above the impedance peak.
Thanks DT
The plot is raw data. No curve fitting or processing
Again for fun.
This is the impedance plot for the FaitalPro HF108R 16R with the STH100 waveguide.
I like to cross these over at or above 2kHz, well above the impedance peak.
Thanks DT
The plot is raw data. No curve fitting or processing
Even if a driver exhibits breakup - like 18Sound ND1460A or RCF ND850, it doesn't necessarily have to sound annoying, as long as the resonances are reasonably dampened by e.g. a soft suspension - which is the case with the 18Sound and RCF.
The STH100 is a shallow horn, hence your comment about the similarities between the STH and an OSWG.
Docali measured the HF108 with one of his Neile horns, which shows the effect of loading on the impedance (blue):
And let's not forget the difference (diaphragm) between the HF108R and the non-R version.
Both 16 Ohm:
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I agree. Also considering the volumes we listen at compared to the intended output levels of drivers such as these such distortions won't be perceptible in any negative way.
This is just a personal perspective right? I don't see how increasing reflections creates more neutrality...Or how adding decay reduces fatigue...
Conveniently I have a pair (Tractrix 350 Hz )that needs a home, though mine are Elliptical. Actually these Elliptical Tractrix horns are the only Tractrix horns I've heard... and even then you have to say "tractrix" without knowing the exact formula used to create the curves. On axis they are lacking large peaks and nulls before eq. Simple EQ rendered very good results. Coming from years of Dynamic Drivers in studio monitors, the horns are neutral in characterto my ear, which is how the people on the board described Tractrix to be in my thread. The criticism has seem to always be the narrow Upper mid to HF polar, limiting the sweet spot size. Never bothered me but to each their own.
The waveguides I've seen are definitely an improvement. and as long as headroom is good, and the Driver can be crossed properly at desired frequency, a waveguide is the choice option it seems. No waveguide allowed me to cross at 200hz. I think a properly designed round or elliptical horn is the next best choice.
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It seems that lots have a liking for Bi-Radials but I am almost certain its just a matter of sweet spot size with a twist of complication of manufacturing an elliptical versus a bi-radial. The height and width will be a factor in clarity. I entertained a large Bi-radial but to reach my ideas of loading the projected width was ridiculous for a ~150-200hz loading biradial. The rate of expansion could have been lessened, creating a longer bi-radial that loaded deep, was long, but not so wide, and with a higher Directivity Index within the range of effective directivity....I'm not the one to lead these discussions though as I am not an expert on horns like those here, still I can accurately describe my experiences and expectations it seems.
Wider dispersion HF will always be triumphed by Higher directivity, in my book... Room treatment consequentially lowers reflective energy. A person will then report back their experience of increased clarity...the same increase in clarity that can be achieved or surpassed by the high DI HF response of a horn or waveguide designed to be so. High DI HF response in combination with Room Treatment, will render more clarity than the Wide Dispersion HF solution in combo with Room Treatment... Its simply a ratio of Direct and Indirect Sound, vs Sweet spot size. People really like a wide sweet spot, though not every is bothered by a small one.
It is my opinion, that I hear a significant increase in clarity in HF from my large Elliptical horn, then I have ever heard in any other system I've demo'd or owned. I am thinking I can pick out more detail from my Horn than my pair of HD600's. Which makes not a lot of sense considering the top end of a 2" exit driver isn't better than a 1", let alone a pair of nice headphones. Headphones have their own issues with perception, but as far as loudspeakers are concerned, increasing directivity is the single most potent increase in clarity when all the other ingredients are proper.
The secret is likely that a wide dispersion Horn/Waveguide in regards to HF always measures Worse at the Listening position, insitu, compared to a well designed Horn/Waveguide with a Higher Directivity HF.... They look great in anechoic though! 😉
Wider dispersion HF will always be triumphed by Higher directivity, in my book... Room treatment consequentially lowers reflective energy. A person will then report back their experience of increased clarity...the same increase in clarity that can be achieved or surpassed by the high DI HF response of a horn or waveguide designed to be so. High DI HF response in combination with Room Treatment, will render more clarity than the Wide Dispersion HF solution in combo with Room Treatment... Its simply a ratio of Direct and Indirect Sound, vs Sweet spot size. People really like a wide sweet spot, though not every is bothered by a small one.
It is my opinion, that I hear a significant increase in clarity in HF from my large Elliptical horn, then I have ever heard in any other system I've demo'd or owned. I am thinking I can pick out more detail from my Horn than my pair of HD600's. Which makes not a lot of sense considering the top end of a 2" exit driver isn't better than a 1", let alone a pair of nice headphones. Headphones have their own issues with perception, but as far as loudspeakers are concerned, increasing directivity is the single most potent increase in clarity when all the other ingredients are proper.
The secret is likely that a wide dispersion Horn/Waveguide in regards to HF always measures Worse at the Listening position, insitu, compared to a well designed Horn/Waveguide with a Higher Directivity HF.... They look great in anechoic though! 😉
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It is about the balance between direct sound for clarity and reflected sound for a sense of space.
Most of my focus here in this thread is the speakers on my bench which I listen to most often, they are in near-field or more correctly direct-field. As I listen the speakers are much closer in time and space than the room reflections. There is nice detail and space.
The speakers toe-in and cross in front of my listening position. As I move from left to right I am nearer to the right speaker however I am off axis on the right and on axis for the left speaker. There is a relative balance between the speakers, the same as when I move right to left.
The speakers are sealed 0.55 cubic foot enclosures with 6 1/2 inch 8Ohm Purifi mid-woofers and this time out FaitalPro HF108R's with STH100 waveguides.
The FaitalPro HF108R's with STH100 waveguides match the 6 1/2 inch 8Ohm Purifi mid-woofers for the lowest distortion. Both drivers and waveguide formfactors look nice on the front baffle of the bench size enclosure.
Thanks DT