To Troels or not to Troels?

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#162
motokok said:
Hi @EmuMannen I browsed your blog -- some interesting comments. What is this Vituixcad "psychoacoustic curve" that you mentioned when tuning your crossover?
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I don't think I mentioned a psychoacoustic curve in VituixCAD but I often refer to psychoacoustic smoothing applied in REW. You can apply the following types of smoothing in REW:
  • 1/1 Octave Smoothing
  • 1/2 Octave Smoothing
  • 1/3 Octave Smoothing
  • 1/6 Octave Smoothing
  • 1/12 Octave Smoothing
  • 1/24 Octave Smoothing
  • 1/48 Octave Smoothing
  • Variable Smoothing
  • Psychoacoustic Smoothing
  • ERB Smoothing
Variable smoothing applies 1/48 octave below 100 Hz, 1/3 octave above 10 kHz and varies between 1/48 and 1/3 octave from 100 Hz to 10 kHz, reaching 1/6 octave at 1 kHz. Variable smoothing is recommended for responses that are to be equalised.

Psychoacoustic smoothing uses 1/3 octave below 100Hz, 1/6 octave above 1 kHz and varies from 1/3 octave to 1/6 octave between 100 Hz and 1 kHz. It also applies more weighting to peaks by using a cubic mean (cube root of the average of the cubed values) to produce a plot that more closely corresponds to the perceived frequency response.

ERB smoothing uses a variable smoothing bandwidth that corresponds to the ear's Equivalent Rectangular Bandwidth, which is (107.77f + 24.673) Hz, where f is in kHz. At low frequencies this gives heavy smoothing, about 1 octave at 50Hz, 1/2 octave at 100 Hz, 1/3 octave at 200 Hz then levelling out to approximately 1/6 octave above 1 kHz.
 
#164
Rodeodave said:
I made the switch from 2-way active speakers with active line level crossovers to 3-way speakers with passive crossovers recently.

I'm not a fan of complex crossovers at speaker level (ruling out most of Troels' other designs), which is why I chose the CNO Grande with its 1st order crossover. The favorable reviews of the W18NX003 supported the decision. See https://hificompass.com/en/reviews/seas-excel-6-w18nx003-e0096-08-midwoofer-review for example.

The same source has a favorable review of the Purifi driver (both 8R and 4R version): https://hificompass.com/en/reviews/purifi-ptt65w08-01b-ptt65x08-nfa-01

Either way, this being a DIY site, I can't quite relate to all the recommendations for going the commercial route. Then again, since I lack the tools, space and frankly also the skills to make an enclosure that would've satisfied my building standards, I got the cabinets made by a carpenter. It's kinda like getting the drilled and tapped amp enclosures from the diyaudiostore methinks, so I'm still calling them DIY speakers 😉
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I’m currently looking for some active speakers and found your post interesting. Curious why you switched?
What actives were you using?
I’ve considered diy but I too may not have the skills. I did look at Purifi and D class amplification. Just want to experience actives and hear how they compare to passive.
Dynaudio Xeo currently has my attention. Considered Kef but trying to stay away from metal cone’s.
Suggestions?

Thanks
 
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#165
Aside from the 'improvement' in sound. Taking my two-ways active made it 'easier' for me to implement a 'house curve' in my room.
The house curve made a huge difference because I had too little bass and was way too bright for my room.

Regards,
Dan
 
#166
intojazz said:
I’m currently looking for some active speakers and found your post interesting. Curious why you switched?
What actives were you using?
I’ve considered diy but I too may not have the skills. I did look at Purifi and D class amplification. Just want to experience actives and hear how they compare to passive.
Dynaudio Xeo currently has my attention. Considered Kef but trying to stay away from metal cone’s.
Suggestions?

Thanks
Click to expand...
I was using a SEAS U18RNX/P with a Morel ST728 in a tapered quarter wave transmission line enclosure. 3rd order active line level crossover with BSC. Amplification varied between Class A amps like the diy Sony Vfet and a mini Aleph J, and a pair of LM4780/3886 chipamps.

I switched to a three way speaker with passive XO (1st order however) because I wanted something new and possibly better, and something that I can power from a single low wattage amp.

Some days I miss the old setup, most days I don't 🙂
 
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#169
hello,

Troels' latest project, the Fusion 22 makes me really want it. I love this speaker format. I don't see the cutoff frequencies anywhere...
What do you think ? the Hp choose are top of the range.
do you think this kind of achievement? expensive can compete with speakers like Harbeth M40, yamaha ns 1000 ......
 
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#172
Check out the Travelers. Those are supposed to compete with the Bordeaux in the mid range.
You'll have to look them up on I believe HT guide or parts express forum.

Curt wrote a few posts regarding the mid-range tunnel design and his goals with using that technique. It's a very interesting read. I'll try to post it later today.
 
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#173
intojazz said:
With passive speakers I’ve always struggled with matching them to an amplifier. Supposedly that part of the equation is eliminated with active speakers.?
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If you have concerns about the load presented to the amplifier, know that speaker drivers have a varying impedance even without a crossover. Ironically you would have to add passive components to make it appear as a resistive load to the amp.
 
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#175
Sebas75003 said:
What do you think ?
Click to expand...
What is the benefit of having the MT upside down?

time-alignment.png
 
#176
Curt C: My whole purpose of the ‘tunnel mid’ design is to eliminate or attenuate the resonance that plagues most all sealed box designs. Standing wave propagation as well as simple reflections of the back wave can cause aberrations and smearing of the sound. A cylindrical ‘enclosure’ of a slightly larger diameter than the driver eliminates any standing wave propagation with the exception of the reflection along its length, which is due to the abrupt change in acoustic impedance at its terminus whether open or closed. Lining the tunnel with 1” foam and adding a foam plug somewhere near the rear of the tunnel provides sufficient length of material to attenuate most audible resonance due to standing waves. While the cylindrical enclosure can be utilized with the terminus closed, any practical length is still plagued with some acoustic energy reflected back through the cone. My experience suggests this excess energy is less intrusive if allowed to leak out the rear of the enclosure where it blends with the reverberant sound field and generally not perceived as first arrival sound.\
Click to expand...

Spot on, the same reason i use aperiodic midTLs, they tend to suck up the entire back wave.

His suggestion of how to design it, seems to be overkill.

I use a 10-1 tapered TL as deep as the enclosure… given an XO of typically >200-250 Hz XO the effective length (remember a tapered line [smaller at the terminus) has an efective length lof the line is onger than a cyclinder of the same length.

If it is still not long enuff fold it back on itself.

This is the midTL out of our A12pw MTM.

midTL-snippet.png


dave
 
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