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

[fluid]

Seems that the Purifi is not so pure,is it?How can that be,specially if is known matter to the company?
And if there is a solution should that be written in the product PDF?
Strange things...

Try and keep some perspective on the magnitude of the issue just from the driver. In the test above the 380Hz peak was at -65dB relative to the fundamental, that is 0.05% distortion.

 

[SDC]

This is a different driver

This is X range Purifi unit with higher Mms than NFA

if X and Mms is problem what makes NAA's motor so different?

Frequency could be different but there is no other frequency that pops out

also unit is not grounded by the magnet.

Just direct contact to aluminum with enough compression.

If gasket Purifi put there is problem I can ask the reviewer to remove it with knife or something.

I allowed reviewer to push the unit to Xmech, because I don't want incomplete unit in my speaker. There are better unit for meh out there. I bought it because it is Purifi. Lars said what, I want more than just a sentence about the unit.

 

[Sokel]

Try and keep some perspective on the magnitude of the issue just from the driver. In the test above the 380Hz peak was at -65dB relative to the fundamental, that is 0.05% distortion.

So why are we presenting this as a problem?
0.05% distortion is insignificant.

 

[SDC]

So why are we presenting this as a problem?
0.05% distortion is insignificant.

Cause somebody thought that 0.05% scientifically exploded to a giant peak.

 

[amirm]

@Nuyes Why are you contradicting the designer of the driver, Lars Risbo? Alan has already posted his conversation with Lars about the resonance. Do you think you know better than Lars?

Your next post better not be through a VPN or we will ban you as another puppet account.

 

[Thomas_A]

Cause somebody thought that 0.05% scientifically exploded to a giant peak.

It excites a structural resonance of the cabinet? Vibration can also be transmitted and excite resonances in structures where the speaker is situated. As below.

https://www.audiosciencereview.com/forum/index.php?attachments/soft-vs-hard-coupling-png.113117/

 

[HHH]

It excites a structural resonance of the cabinet? Vibration can also be transmitted and excite resonances in structures where the speaker is situated. As below.

https://www.audiosciencereview.com/forum/index.php?attachments/soft-vs-hard-coupling-png.113117/

That's right. And it's a speaker problem, not a unit problem.

 

[Nuyes]

It excites a structural resonance of the cabinet? Vibration can also be transmitted and excite resonances in structures where the speaker is situated. As below.

https://www.audiosciencereview.com/forum/index.php?attachments/soft-vs-hard-coupling-png.113117/

I understand what you are talking about.

Suppose the Sointuva WG has an enclosure that is not well designed enough.
And Alan claimed that March audio had the know-how to overcome it (at first he didn't talk about bolt torque. Treating bolt torque related things as a secret source), if the secret is true...

Alan should not have contacted the owner directly for the leaking binding post issue.

He should have given him the 'correct torque value' he claims, even if he asks for repairs himself.

This is a very important point.

In fact, if Alan had been that kind of friendly in initial customer service, I didn't have to escalate the case this much.


+

And I tightened the bolts in most situations while repeating the various tests.
However, there was no additional increase in distortion in the process.

If so, have the bolts of Sample A already shipped from Alan overtightened?

 

[SDC]

Just post a photo of distortion data Lars shared with you. They are going to fix it in their next unit anyway. And I could be happy to leave Purifi without regret.

 

[Thomas_A]

I understand what you are talking about.

Suppose the Sointuva WG has an enclosure that is not well designed enough.
And Alan claimed that March audio had the know-how to overcome it (at first he didn't talk about bolt torque. Treating bolt torque related things as a secret source), if the secret is true...

Alan should not have contacted the owner directly for the leaking binding post issue.

He should have given him the 'correct torque value' he claims, even if he asks for repairs himself.

This is a very important point.

In fact, if Alan had been that kind of friendly in initial customer service, I didn't have to escalate the case this much.

I think as I said in a previous post, issues seems to be a mixed bag.

(IMO: Applying looser bolt torque is not a solution for several reasons, e.g. torque can and will change over time when using wood as speaker enclosure. Also, IMO, enclosures using drivers with high motor power and putative high risk of excitation of audible structural resonances should have lossy and damping sandwich construction and/or braces at correct positions.)

 

[Nuyes]

I think as I said in a previous post, issues seems to be a mixed bag.

(IMO: Applying looser bolt torque is not a solution for several reasons, e.g. torque can and will change over time when using wood as speaker enclosure. Also, IMO, enclosures using drivers with high motor power and putative high risk of excitation of audible structural resonances should have lossy and damping sandwich construction and/or braces at correct positions.)

I really agree with your comments.

Thanks for broadening your knowledge.

 

[BDWoody]

We have some very determined puppets this morning...

I'll start marking them as spam for the databases.

If you are just signing up to whine in this thread, don't.

---

 

[julbo]

The single pair I heard sounded pretty darn good, so i suspect that with improved QC that they should all end up matched.

I was trying to get them with the passive XO outboard/external and using a Neutrik SpeakOn between the XO and box.
Maybe a single 4-pole SpeakOn would mitigate the leaks?
(But silicon would also seal it just fine.)




The OP did post the main correspondence, and people read them as polite or demeaning depending on how they wanted to read them.
(They looked OK to me.)

Funny you mention that, had considerable leakage from the SpeakOn that needed some gluing and stuffing both socket and connector.
I also had leakage from the PR and a bit from the tweeter (Directiva r1), solved with soft cardboard gaskets

 

[boXem]

Before some people start thinking that a "huge" flaw in the Purifi driver was discovered today:
- any mechanical object on earth has a self resonance frequency
- any mechanical assembly on earth has a self resonance frequency
- the amplitude of this resonance can be lowered (or increased) by modifications
- the frequency of this resonance can be changed by modification
- the resonance can not be suppressed, just mitigated
As usual with engineering, a tradeoff needs to be done between the function, the reliability, the manufacturability, the cost, ...

From the experiment done by @Nuyes it seems here that the self resonance from the assembly or from one sub-assembly of from one component is around 380-400 Hz. It seems to be very well mitigated since the noticeable effect is a 0.05% distortion.

 

[YSC]

I think as I said in a previous post, issues seems to be a mixed bag.

(IMO: Applying looser bolt torque is not a solution for several reasons, e.g. torque can and will change over time when using wood as speaker enclosure. Also, IMO, enclosures using drivers with high motor power and putative high risk of excitation of audible structural resonances should have lossy and damping sandwich construction and/or braces at correct positions.)

Just wonders when most speakers out there using wood or MDF for cabinet, would getting prolonged use of sealed cabinet or PR design eventually makes the driver loose beyond re-tightening ?

 

[theREALdotnet]

Just wonders when most speakers out there using wood or MDF for cabinet, would getting prolonged use of sealed cabinet or PR design eventually makes the driver loose beyond re-tightening ?

I suppose in virtually all cases some kind of fastener system other than wood screws would be employed to hold the drivers. My sealed speakers for example are made from ply and the drivers are held in place by bolts and nuts through the baffle, with gaskets to seal the holes.

 

[Jason K]

It is necessary to check whether Purifi's engineers mean that there is a basket resonance around 400Hz that occurs as much as the distortion level in the data measured by the OP.

Purifi's driver was clean as NAA measured by the OP and NFA measured from Sointuva and a lot of third-party measurement data.

It is similar to the level the OP measured.

Below is the measurement of NFA by Erin and NAA by OP.

And this is Sointuva 85dB distortion data by OP

it is necessary to put a little more effort into identifying the cause rather than being defensive against the increased distortion that only when it is mounted in a box

We are talking about data, not measurers.

 

[mdsimon2]

Interesting thread. Certainly brings in to question the resonance at around the same frequency that was present in the Directiva review and attributed to amp / DSP on top of the speaker but not explored further. To me this thread suggests that the resonance was real and not the result of gear on top of the speaker.

Michael

 

[Holmz]

Funny you mention that, had considerable leakage from the SpeakOn that needed some gluing and stuffing both socket and connector.
I also had leakage from the PR and a bit from the tweeter (Directiva r1), solved with soft cardboard gaskets

Thanks.

 

[Holmz]

…
And this is Sointuva 85dB distortion data by OP

View attachment 215540View attachment 215541
...

That looks like a quiet place.