Kwesi, yes, I generally agree, with the first part. Sometimes it takes time to make the driver sound the way you want to and there is learning curve. It is likely nowadays I would manage to breathe more life in DXT. So, what specifically is the magic DXT needs to make it sounding right? Based on the measurements I provided, the implementation is good. Off axis of the bare tweeter is perfect, crossover, phase tracking, spinorama , that all is fine. I tried a lot of tweaking of the response, but basic character was still the same.
I have worked with tens of the tweeters over the years, but dxt stands out in my tweeter list as the last tweeter I would want to use again.
I even like ring radiators which are often described as dull, boring, lacking sparkle, weak off axis.
I have worked with tens of the tweeters over the years, but dxt stands out in my tweeter list as the last tweeter I would want to use again.
I even like ring radiators which are often described as dull, boring, lacking sparkle, weak off axis.
Can you describe what is not right or missing with the dxt?
is it clarity or dynamics or smearing or difficult to understand the words in a song or ?
I am very interested in this and also looking at the measurements of the dxt and comparing these with my sb26adc in a 4 inch waveguide of @augerpro which sounds fine to my ears. Better than the accuton c30-6-024.
is it clarity or dynamics or smearing or difficult to understand the words in a song or ?
I am very interested in this and also looking at the measurements of the dxt and comparing these with my sb26adc in a 4 inch waveguide of @augerpro which sounds fine to my ears. Better than the accuton c30-6-024.
OK I will try to elaborate on the sound of DXT....
You mentioned SB26ADC in Augerpro WG. I know ADC well, I have worked with it, without WG, and I liked that tweeter, and I can imagine in WG it would be even better, based on my experiences with waveguides. I know also Accuton C20, not my cup of tea though overall good sounding tweeter.
DXT, compared to ADC, 9800, T34A, and basically other tweeters, sounded dull in the sense of clarity, it was somewhat veiled, subjectively lacking top octaves. It was like you put the blanket over the tweeter. Increasing the level did not help.
From this review of SEAS H1499 27TBCD/GB-DXT https://www.audioexcite.com/?page_id=2242
"
Unfortunately however, due to the measurement setup these distortion plots don’t tell the whole truth about this tweeters distortion profile. The cone break-up at 27kHz causes a rise in the distortion profile at 13.5kHz for the second-order, 9kHz for the third-order and 5.4kHz for the fifth-order harmonics and so on.
These distortion spikes will contribute to the tweeters sound character. Some people call it “metallic sound”, other think it adds additional resolution and details to the sound. I say it’s a matter of personal preferences and taste, if it’s good or not
"
"
Unfortunately however, due to the measurement setup these distortion plots don’t tell the whole truth about this tweeters distortion profile. The cone break-up at 27kHz causes a rise in the distortion profile at 13.5kHz for the second-order, 9kHz for the third-order and 5.4kHz for the fifth-order harmonics and so on.
These distortion spikes will contribute to the tweeters sound character. Some people call it “metallic sound”, other think it adds additional resolution and details to the sound. I say it’s a matter of personal preferences and taste, if it’s good or not
"
That's intended with the horn........about the worst thing you can do to that ribbon.
No accounting for taste.....some people like that headphone in the room thing
GRS makes em now......they bought Fountek's intellectual property
Look at that response from 4k out....that's all you Jim!.........that larger ribbon will outplay any dome any day of the week
Take away the horn loading and the horizontal is out to 90.......doesn't get much better
......you just better be sitting down! LOL cause the vertical is extremely narrow
Perhaps by those who do not understand it causes and uses or misuses. Diffraction is an inevitable situation in a speaker with a finite baffle. It can be useful and controlled or harmful and uncontrolled or anywhere in between. It is always predictable and relatively easy to avoid the few obvious negative effects either through simulation or cut and try.
I have designed more waveguides for the T25A than any other tweeter 🙂 The T25A behaves like a bucking bronco in the kind of waveguides that many people want or ask for. It resists all attempts (I have tried every trick I can think of) to narrow it's directivity with an ugly cancellation in the very high KHz region.
But so does the T34A and the solution for that driver is to let it be as wide as it wants and change the profile very gradually. I suspect that the T25A can do the same, but no one ever asks for a very large thin waveguide for a small dome. If you want when I have access to my server I can see what can be done with it in than direction.
Thank you, yes, I would be interested in exploring this option. The radiation pattern from a flat-face small dome like the T25 is rather good in my latest simulation. If the directivity in the 3k - 6k region could be narrowed and smoothed just a bit, I think it would be perfect. The maximum outer diameter for a waveguide would be 120 mm... I run into geometric interference at larger diameters.
j.
This is the latest set of sims. I managed to smooth out the DI curve a bit by adding some ellipticity to the low pass and high pass filters.
First is the SB26CDC which is my proxy for a small metal dome (i.e. T25A)
Next is the Satori TW29TXN-B, which is my proxy for a large dome with a rather narrow HF pattern
And finally, the SBA SB26STWGC which represents a smallish waveguide
j.
First is the SB26CDC which is my proxy for a small metal dome (i.e. T25A)
Next is the Satori TW29TXN-B, which is my proxy for a large dome with a rather narrow HF pattern
And finally, the SBA SB26STWGC which represents a smallish waveguide
j.
Interesting XO. You have a flat DI where hearing is sensitive to group delay.
I found on my XO to a 10" with a dome, a LR4 a little higher than 500hz gave a better DI.
Bliesma T25A dispersion really looks like it has a shallow wg, very much like SEAS DXT! Should be nice!
Magnetostat PA ribbon from Monacor has flat dispersion index. Highish distortion% does not rise with spl! Peak at 15kHz might sound sparky!
https://www.hifitest.de/test/lautsprecherchassis-hochtoener/img-stageline-rbt-1000-6625
Magnetostat PA ribbon from Monacor has flat dispersion index. Highish distortion% does not rise with spl! Peak at 15kHz might sound sparky!
https://www.hifitest.de/test/lautsprecherchassis-hochtoener/img-stageline-rbt-1000-6625
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The T25a was certainly well thought out for what it’s meant for…..a very high crossover point with a small chassis for close C to C placement…….meaning it would work very well with a dome mid……perfect actually.
The only real limiting factor might be power handling I suppose…….
The only real limiting factor might be power handling I suppose…….
I will see what I can do, it will be at least a week before I am back and able to simulate anything. If you have the dimensions of your baffle and cabinet depth I can put those or somethig similar into the simulation.
Thank you again for your offer to help 🙂... I understand that the T25A is a difficult little driver to waveguide, so whatever effort you expend will be appreciated, even if it results in nothing.
It seems like Seas E0110(the new Textreme dome tweeter with a small waveguide) would work well with M74A. Crossover at 4KHZ, their directivity is pretty much alike.
---but see how DI rises above 4kHz!
vs. DXT (below) or Bliesma T25A (imagine 1st order highpass at 6000Hz and you'll have acoustic LR2 around 3000Hz )
vs. DXT (below) or Bliesma T25A (imagine 1st order highpass at 6000Hz and you'll have acoustic LR2 around 3000Hz )
I have been finalizing the design for the stand, which will house a new Hypex FA253 amp. The stand will be about 430 mm (17") tall. This will be a multipurpose stand to serve future projects as well as this one.
I have decided that I will use an IcePower 300AS1 amp to drive each of the SB34NRX75-6 woofers, which now become subwoofers for this project. My intent is to cross to the main 3-way speakers in the 80 - 100 Hz range. I plan on putting the amps in Ghent Audio cases. Whoever made me aware of Ghent audio, thanks !
I will use a MiniDSP Flex to handle the filtering for the subs. This is a 2-in / 4-out DSP processor. The Hypex amps will of course handle the filtering for the main 3-way.
I have also chosen to use the Scan Speak 26W-4867T00 as the woofer, and the Bliesma T25A as the tweeter. The tweeter may have a waveguide, depending on what sort of magic that @fluid can conjure up...
Here is the latest sim using the SB26CDC as a stand-in for the Bliesma T25A, and also including the subwoofers. I have gone about as far as I can go with hypothetical drivers and stand-in drivers. Any further refinement would be silly without measurements of the actual drivers installed in the cabinets. The design looks quite nice to me, so I am confident in proceeding to the next phase: purchasing the other drivers and building stuff...
Happy new year....... j.
I have decided that I will use an IcePower 300AS1 amp to drive each of the SB34NRX75-6 woofers, which now become subwoofers for this project. My intent is to cross to the main 3-way speakers in the 80 - 100 Hz range. I plan on putting the amps in Ghent Audio cases. Whoever made me aware of Ghent audio, thanks !
I will use a MiniDSP Flex to handle the filtering for the subs. This is a 2-in / 4-out DSP processor. The Hypex amps will of course handle the filtering for the main 3-way.
I have also chosen to use the Scan Speak 26W-4867T00 as the woofer, and the Bliesma T25A as the tweeter. The tweeter may have a waveguide, depending on what sort of magic that @fluid can conjure up...
Here is the latest sim using the SB26CDC as a stand-in for the Bliesma T25A, and also including the subwoofers. I have gone about as far as I can go with hypothetical drivers and stand-in drivers. Any further refinement would be silly without measurements of the actual drivers installed in the cabinets. The design looks quite nice to me, so I am confident in proceeding to the next phase: purchasing the other drivers and building stuff...
Happy new year....... j.
Great driver selection just to my taste 😉 and nice Simulation!
I have currently paired a T25A to a Kartesian Mid120_vHE that has comparable Sd to the M74A with very flat, wide dispersing cone and optimization gave 2,7kHz crossover frequency for best overall power response, so applied/optimized xover frequency in your simulation comes out plausible to me in a range as expected.
Some idea for the capability to apply a LR2 highpass to the M74A:
In the speaker with the Mid120, I applied a series resistor with Rs = RDC (+ a passive series notch on the breakup area) to give the driver some local current feedback for bit thermal compression and hysteresis distortion reduction. This also, as side effect, rises the Q of the driver and "linearizes" the lower end FR, if you may call it so:
But your amp needs some voltage swing left, with Rs = around RDC of the driver you would quarter the rail limited power the amp can deliver (I have a FA503, so with the series resistor there is still ~100W available for the driver).
I would be curious on the power response just in the horizontal domain / from the horizontal FR simulations. Do you mind to show a screenshot? Thanks a lot!
Best regards
Peter
I have currently paired a T25A to a Kartesian Mid120_vHE that has comparable Sd to the M74A with very flat, wide dispersing cone and optimization gave 2,7kHz crossover frequency for best overall power response, so applied/optimized xover frequency in your simulation comes out plausible to me in a range as expected.
Some idea for the capability to apply a LR2 highpass to the M74A:
In the speaker with the Mid120, I applied a series resistor with Rs = RDC (+ a passive series notch on the breakup area) to give the driver some local current feedback for bit thermal compression and hysteresis distortion reduction. This also, as side effect, rises the Q of the driver and "linearizes" the lower end FR, if you may call it so:
But your amp needs some voltage swing left, with Rs = around RDC of the driver you would quarter the rail limited power the amp can deliver (I have a FA503, so with the series resistor there is still ~100W available for the driver).
I would be curious on the power response just in the horizontal domain / from the horizontal FR simulations. Do you mind to show a screenshot? Thanks a lot!
Best regards
Peter
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That's also my experience with the DXT. I owned a speaker with it and was not happy. Also as far as I know the older Genelecs use the same tweeter but with custom Waveguide, same sound signature for me (maybe even worse).
A lot of details at high frequencies but they don't sound "real". Like a magnifying glass with 8bit resolution 🤓
A friend of mine (also sound engineer) built a few speakers with the DXT and similar generation Seas and finally switched to T25A after I told him for years ... there is no coming back, he reported me exactly the same as I experienced. He was surprised how clean a metal dome can sound.
When you are used to that "metal sound" it is fine of course. Some even like/need that, it can help for recording/mixing to find flaws quickly. When the tweeter is linearised it doesn't lack hf or sounds dull in my experience but off axis is of course not the same as we can do now with a good waveguide. Don't forget, this design is OLD.
And ring radiator - they have narrow beaming at high frequencies caused by their big surface. I really like the sound of these (resonance free, natural) but you never get it balanced between nearfield and in room response. Linear on axis they sound a bit hf lacking in the room - dull. Good in the room - stay away from on axis.