So is it industrial standard to mount it via the magnet? That's what I'm questioning.Most likely because they isolated the driver from the baffle with damping or mounted it via the magnet.
So is it industrial standard to mount it via the magnet? That's what I'm questioning.Most likely because they isolated the driver from the baffle with damping or mounted it via the magnet.
Is the cabinet brace between the left and right walls an oak dowel? Does it ring with a characteristic frequency around where you are seeing the distortion? I was just wondering, since I have always thought these type of braces ring.
Not usually, but most drivers do not have the motor force, excursion and generally low distortion to make the effect so obvious. I did edit the post above to add another reason but on checking they measured at 2.83V which does produce an SPL of about 86dB.So is it industrial standard to mount it via the magnet? That's what I'm questioning.
Not usually, but most drivers do not have the motor force, excursion and generally low distortion to make the effect so obvious. I did edit the post above to add another reason but on checking they measured at 2.83V which does produce an SPL of about 86dB.
Then it should have been in some kind of app note. Not having it means people don't know to deal with it.
You are welcomeThanks for all the informations!
The KEF reference 104.2 and 105.2 with the 107.2 used a non-ferrous coupling rod with threading on each end that went through the woofers to clamp them via the magnet. It was called, "Coupled cavity."So is it industrial standard to mount it via the magnet? That's what I'm questioning.
The KEF reference 104.2 and 105.2 with the 107.2 used a non-ferrous coupling rod with threading on each end that went through the woofers to clamp them via the magnet. It was called, "Coupled cavity."
Thanks for the good tests and comments.Is the cabinet brace between the left and right walls an oak dowel? Does it ring with a characteristic frequency around where you are seeing the distortion? I was just wondering, since I have always thought these type of braces ring.
I measured some random dowels I had lying around the shop, different lengths and diameters. I suspended each with string, and struck them with a soft mallet to try to get the fundamental excited. These are just the dowel in free air, so no idea how this will change when this element is incorporated into the speaker.
View attachment 215217
Any possibility the brace is a problem? Did the extra stuffing you added and harnessing the wire also damp the brace?
OK, good point. Thanks for reminding me.Thanks for the good tests and comments.
If bracing was the cause of the problem, both speakers should show the same symptoms.
But I couldn't find it.
Thank you for sharing useful information and knowledge.You are welcome
Just to round it out here is a distortion graph from Hificompass at two different SPL's you can see that at the lower one there is a peak of 3rd Harmonic at 380Hz and then at 100dB there is a slight peak of 5th Harmonic at about 420Hz.
https://hificompass.com/en/reviews/purifi-ptt65w08-01b-ptt65x08-nfa-01
View attachment 215218
Do you mean add it to the original post for the thread? If so, sure, you can just hit edit on that post and cut and paste it. Alternatively just put a link in the original article to this new post. If you have trouble let me know.Is there any way for me to add this to the body of the thread?
Thanks for kind support.Do you mean add it to the original post for the thread? If so, sure, you can just hit edit on that post and cut and paste it. Alternatively just put a link in the original article to this new post. If you have trouble let me know.
Thank you for sharing useful information and knowledge.
Here is some material I'd like to add for clarification.
View attachment 215257
1. THD, which does not increase proportionally, is rather modest at about 2.82V.
2.You may remember I tested the Sointuva WG with a hermetic one.
It is CNC machined to the same size as Purifi's Passive Radiator with great precision.
View attachment 215259
And as a result I can find similar resonances as well.
The problem with the Purifi driver you mentioned is related to the peak of the 3rd harmonic at 380hz.
However, I found that both the second harmonic and the higher harmonic had peaks at a constant ratio.
This is similar to the room mode that occurs in the listening space.
Through simple calculations, we can see that the length of the space that generates the first resonance of about 400 Hz is about 43 cm (16.9 inches).
And, coincidentally, the height of the Sointuva WG is 45cm (17.7inch) according to the manufacturer's specifications.
Considering the thickness of the speaker enclosure, I thought that this could be the room mode resonance due to the internal floor height.
And if this is the resonance caused by the room mode, this resonance also cannot increase linearly with respect to the output.
This is because the internal structure of this speaker itself is not a perfectly rigid wall.
I thought this was a sufficiently possible scenario.
And, this is why I added sound absorbing material inside this speaker.
And below is the measurement data of sample B.
Similarly, it can be found that everything from the second harmonic to the higher order harmonic soars in a similar frequency band.
View attachment 215258
If the cause of the THD pointed out in the original article is the 380hz/3rd harmonic inherent to the Purifi driver, it cannot explain this symptom.
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@amirm , I'm sorry for tagging you carelessly.
I leave this question because I haven't gotten used to the way this website works yet.
Starting this thread was a huge process for me, and so was the outcome.
So there are some missing steps. Just like in this post.
Is there any way for me to add this to the body of the thread?
I am afraid that all this will evaporate through my hasty action.
With great interest i've readed the whole thread and one question pops up in my head:
Is Alan manufacturing the speakers himself, or did he outsourced it to another country? you all know what i mean.
Thanks! So QC is his direct responcebility.He coops with woodmakers near him in Australia.
Your test to determine the natural frequencies of the dowels consisted of what is known as a free–free condition. When mounted as a brace in the loudspeaker cabinet, the dowel fitment will likely approximate a somewhat lossy clamped–clamped support condition. Interestingly, it turns out that the natural frequencies of the dowel under those two quite different support conditions are the same. For example, refer to Blevins (1979), "Formulas for natural frequency and mode shape", Table 8-1, Single span beams.I measured some random dowels I had lying around the shop, different lengths and diameters. I suspended each with string, and struck them with a soft mallet to try to get the fundamental excited. These are just the dowel in free air, so no idea how this will change when this element is incorporated into the speaker.
What has a member's number of posts got to do with conflict of interest?If you cared about objectivity at all , you wouldn't plaster a big sign on a member's profile that they are a MAJOR CONTRIBUTOR. That doesn't present any issues with bias and favoritism. Your hypocrisy truly knows no bounds.