• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

The REAL Problem of March Audio's Sointuva WG (Review, Measurements and Reinforcements with Klippel device)

thin bLue

Senior Member
Reviewer
Joined
Jul 29, 2019
Messages
352
Likes
1,155
More Answers from Marchaudio

20220627_221342.jpg

Screenshot_20220627-203949_Gmail.jpg

Screenshot_20220627-204028_Gmail.png

Screenshot_20220627-204109_Gmail.jpg
 
Last edited:

beagleman

Major Contributor
Joined
Sep 24, 2020
Messages
1,159
Likes
1,582
Location
Pittsburgh Pa
Seeing as my Sointuva's are currently in production and I was concerned, I asked March Audio about the problems suggested by this thread. I got this response. I just included the relevant information. (See BOTH quote boxes!)
Nice to read a view from the manufacturer.

Not to diss on the O.P., but this does make one consider how seeing one view can blind one to a different view.

Many of the points addressed, seem to be viable or possible for sure.
Quite interesting to see, that possibly some conclusions were a bit premature.

Some seemed to so easily condemn a product, based on information, that, while well thought out and time consuming, may not always be for sure the final answer.

Not defending EITHER "Side" in this fiasco, but as with all things, there are Two sides and explanations.
 

fluid

Addicted to Fun and Learning
Joined
Apr 19, 2021
Messages
691
Likes
1,196
I haven't read every post to see if this has been asked ... How is that the purifi driver can be hailed as the bestest lowest distortion driver in the universe if it has a fundamental issue like a nasty fundamental resonance that means it actually has a region of very high distortion?
(*it's quite possible my question is borne of ignorance, apologies if it is)
Some information posted by Lars Risbo

"frame-motor resonance: this is a generic thing for all electrodynamic drivers. there is a heavy motor hanging in the frame which is bolted to a box. The frame acts as a (very stiff) spring and the motor is a mass thus forming a mass spring oscillator. All the Newton forces of the driver goes through this mass-spring system. This makes it very critical how the frame is fixed to the box since the high forces can cause rattling (ie high distortion).

It would be a lot better to mount the driver by its motor which is the source of the Newton forces but this is not standard. The best would be to bolt the motor onto a heavy solid chunk of metal serving as inertial reference to absorb the Newton forces.

Anyway, this is as mentioned a generic problem for all drivers but with the X stroke PTT drivers we have high Mms and a very strong motor in order to get low F3 in a compact box and this means the driver produces more Newtons force for the same SPL compared to a lower Mms driver. This makes the mounting method more critical including how much torque and what materials used etc.

When measuring on the driver laying on its magnet the problem is gone since the Newton forces terminate into the 'ground' and the frame is unterminated so we do not have the mass-spring oscillator."


https://www.diyaudio.com/community/...ifi-woofer-speaker-builds.352063/post-7058058
 

digicidal

Major Contributor
Joined
Jul 6, 2019
Messages
1,981
Likes
4,838
Location
Sin City, NV
Not to put words in his mouth, but the reason why should be very clear: as soon as a reviewer makes changes to a DUT, the manufacturer can blame the reviewer for issues.
This. Exactly. :)
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,586
Likes
38,284
Location
Gold Coast, Queensland, Australia

SDC

Senior Member
Joined
Oct 3, 2019
Messages
328
Likes
508
Location
S.Korea
Ok... So no Al test baffles allowed? My head is starting to boil here... Can't consume all the data
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,586
Likes
38,284
Location
Gold Coast, Queensland, Australia
Or someone is going out of their way to ensure exchange of information on a contentious issue when one of the key parties is banned from the forum.

The best predictor of future behaviour, is, wait for it...past behaviour.
 

PeteL

Major Contributor
Joined
Jun 1, 2020
Messages
3,303
Likes
3,838
Again, I've never tampered with the speakers before taking measurements.
Including bolts.


Alan goes on to say.
"I changed the speaker arbitrarily and then proceeded with the measurement," he said.

But I swear I never touched anything.
Even when passing a bunch of data to Alan through a sample A/B test.
Thank you for clarifying, so it's a difficult solution then. I understood that the solution to this was adding damping material, but if the other sample did not have the issue. Doesn't it proves that the qty of Damping was not the source of this problem? I am a bit confused here, what am I missing? Did the sample B had sealed binding post?
 
Last edited:

thin bLue

Senior Member
Reviewer
Joined
Jul 29, 2019
Messages
352
Likes
1,155
This is just like the "Please Explain" thread when Alan created a sockpuppet account (Zaphod Beeblebrox) after being banned.

Groundhog day!
Hey, I did not do any of behaviours to be banned as I know. Of course I don't have any intent to make troubles too. Please chill. If the moderator's instructions are given, I will 100% follow them!




Add an image for more joyful ASR

IMG_0912_1.gif
 
Last edited:
OP
Nuyes

Nuyes

Active Member
Forum Donor
Reviewer
Joined
Jun 8, 2022
Messages
218
Likes
3,569
Location
South Korea
Thank you for clarifying, so it's a difficult solution then. I understood that the solution to this was adding damping material, but if the other sample did not have the issue. Doesn't it proves that the qty of Damping was not the source of this problem? I am a bit confused here, what am I missing?
I'm no speaker setup expert.
We only focused on the problem of sample A, and after repairing it, we modified B to the same state as A with the user's permission.

And I just double-checked that there is no problem with the correction of sample B, and below is the measurement data of sample B.

01.png
02.png
 

DSJR

Major Contributor
Joined
Jan 27, 2020
Messages
3,314
Likes
4,427
Location
Suffolk Coastal, UK

abdo123

Master Contributor
Forum Donor
Joined
Nov 15, 2020
Messages
7,425
Likes
7,941
Location
Brussels, Belgium
Hey, I did not do any of behaviours to be banned as I know. Of course I don't have any intent to make troubles too. Please chill. If the moderator's instructions are given, I will 100% follow them!




Add an image for more joyful ASR

View attachment 215056
I just get mesmerised with the surround flexing like that. It's suppose to maintain consistent Surface area as the driver push forward or backwards. to minimize doppler distortion. Simply magic.
 

digicidal

Major Contributor
Joined
Jul 6, 2019
Messages
1,981
Likes
4,838
Location
Sin City, NV
It would be a lot better to mount the driver by its motor which is the source of the Newton forces but this is not standard. The best would be to bolt the motor onto a heavy solid chunk of metal serving as inertial reference to absorb the Newton forces.

https://www.diyaudio.com/community/...ifi-woofer-speaker-builds.352063/post-7058058
Also why some designs choose to "link" the motor/magnet assemblies in a horizontally-opposed configuration for large-excursion drivers - either that or by providing substantial back bracing which contacts directly. Either of which are difficult designs to produce (and virtually impossible to produce affordably).

Thank you for clarifying, so it's a difficult solution then. I understood that the solution to this was adding damping material, but if the other sample did not have the issue. Doesn't it proves that the qty of Damping was not the source of this problem? I am a bit confused here, what am I missing?
You're not the only one. Unfortunately there is no purely objective way to determine which is entirely true. March Audio has stated that both units left as tested and identical (or at least within normal tolerances). At the same time the binding post issue alone would seem to indicate variance outside of what I would think "normal QC" would allow. On the opposite side, without doing every single step on video (in one take) for scrutiny... there isn't a way to conclusively prove that issues weren't caused, or at least exacerbated, during modification.

At a guess, the damping is not truly inadequate except in cases where the cabinet, bolts, posts, etc. have become (somehow) mechanically disconnected and/or unsealed themselves?
 

beagleman

Major Contributor
Joined
Sep 24, 2020
Messages
1,159
Likes
1,582
Location
Pittsburgh Pa
Thank you for clarifying, so it's a difficult solution then. I understood that the solution to this was adding damping material, but if the other sample did not have the issue. Doesn't it proves that the qty of Damping was not the source of this problem? I am a bit confused here, what am I missing? Did the sample B had sealed binding post?

There are several inter-related things here. Adding the damping "Could appear" to solve the issue Pete, but also the removal OF the driver and reassembly could change vibrations and resonances also.

Just the process of taking things apart, COULD account for changes.

The true test of proof, would be take the problem sample, then remove the damping and remeasure, and make sure screws are torqued properly.

That will remove (or reduce at least) the possibility or it being driver mounting related.
 
OP
Nuyes

Nuyes

Active Member
Forum Donor
Reviewer
Joined
Jun 8, 2022
Messages
218
Likes
3,569
Location
South Korea
Thank you for clarifying, so it's a difficult solution then. I understood that the solution to this was adding damping material, but if the other sample did not have the issue. Doesn't it proves that the qty of Damping was not the source of this problem? I am a bit confused here, what am I missing? Did the sample B had sealed binding post?
Sample B also had the binding post exposed.
Alan claims this was a QC mistake, but if so, did he 'mistake' the QC of two speakers in a row?
 

thin bLue

Senior Member
Reviewer
Joined
Jul 29, 2019
Messages
352
Likes
1,155
I just get mesmerised with the surround flexing like that. It's suppose to maintain consistent Surface area as the driver push forward or backwards. to minimize doppler distortion. Simply magic.
that's what makes Purifi so SEXY xD
 
Top Bottom