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

AdamG

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samysound

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When it comes to MDF or solid timber, these threaded insert nuts are the preferred mounts for anything that needs a specified fixing torque that is not affected by changes in board thickness due to gassing-off of manufacturing adhesives/binders and/or absorption of moisture resulting in dimensional changes. MDF is remarkably stable in lateral dimensions, but average to poor when it comes to thickness stability.

These inserts are suitable for 16 to 25mm MDF or timber from 20mm and up.

Insert nuts maintain a specific fixing force over the lifetime of the board, assuming correct installation and suitable torquing. ie, they don't come loose or expand the hole they have been jammed into...
View attachment 216064

The fact that March appears to be using well nuts, means he has little idea about timber or board construction techniques. Furniture construction is vastly different to aerospace.
Understanding Bolted joints, torque retention, and pull out strength of inserts in various panel materials is absolutely and aerospace thing…
 

Robbo99999

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Like in the "spruce orbiter"?
Ha, well it's not being said that wood is the material of choice for space exploration!

I'm kinda surprised they offer this speaker in different types of wood cabinet though, mdf vs "real wood", you'd think it would effect the frequency response or distortion to some extent.
 

IPunchCholla

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When it comes to MDF or solid timber, these threaded insert nuts are the preferred mounts for anything that needs a specified fixing torque that is not affected by changes in board thickness due to gassing-off of manufacturing adhesives/binders and/or absorption of moisture resulting in dimensional changes. MDF is remarkably stable in lateral dimensions, but average to poor when it comes to thickness stability.

These inserts are suitable for 16 to 25mm MDF or timber from 20mm and up.

Insert nuts maintain a specific fixing force over the lifetime of the board, assuming correct installation and suitable torquing. ie, they don't come loose or expand the hole they have been jammed into...
View attachment 216064

The fact that March appears to be using well nuts, means he has little idea about timber or board construction techniques. Furniture construction is vastly different to aerospace.
Unless we’re talking about wooden satellites
 

Holmz

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Alan is gossiping amir and OP in his own forum now LOL.

But Alan is making some good points on resonance.
And quoting Bruno on the basket resonance, and that makes sense being that Bruno designed the speaker.
I would suggest that Bruno understands it.

And there was also Erin’s measurements… which are posted here: https://www.audiosciencereview.com/...ns-review-for-the-march-audio-sointuva.29677/
@abdo123 ’s. First sentence fragment start it with, “ I'm just speechless over how good the results are,”
Which sums up how good they sounded to my ear.


When it comes to MDF or solid timber, these threaded insert nuts are the preferred mounts for anything that needs a specified fixing torque that is not affected by changes in board thickness due to gassing-off of manufacturing adhesives/binders and/or absorption of moisture resulting in dimensional changes. MDF is remarkably stable in lateral dimensions, but average to poor when it comes to thickness stability.

These inserts are suitable for 16 to 25mm MDF or timber from 20mm and up.

Insert nuts maintain a specific fixing force over the lifetime of the board, assuming correct installation and suitable torquing. ie, they don't come loose or expand the hole they have been jammed into...
View attachment 216064

The fact that March appears to be using well nuts, means he has little idea about timber or board construction techniques. Furniture construction is vastly different to aerospace.

With all due respect…

I use those fasteners all the time on wood projects.
- Especially when I do not want stuff, like a chair, to fail... as I want to avoid attracting the wrath of the Haus-Frau.

Maybe Alan has more routers than a digital IT router?
But I know for sure that there are actual high-end woodworking shops (or three) in Albany/Denmark area…
I only found out about the MA speaker after seeing the box in that shop... and that shop that does the boxes does a lot of schmicko work.
It’s basically all they do 8 hours /day, along with selling me scraps of off cuts for my Haus-Frau projects.

And while I was thinking along similar lines wth the fasteners…
We do have Bruno‘s input of using compliance to ameliorate the basket resonance.
So if screwing them down (very solidly) to the cabinet is something that Bruno says to avoid, then that nut with (what appears to be a rubber o-ring) might be more of an engineered solution?

We should remember that It is an actual speaker cabinet, and not one of my woodworking furniture restoration projects.
 

fluid

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The fact that March appears to be using well nuts, means he has little idea about timber or board construction techniques. Furniture construction is vastly different to aerospace.
Insert nuts are great, funnily enough though, of all the types available the version in your image are the worst kind for longevity in MDF. They separate the MDF into layers which can fail, at least that is my experience with them. The expensive EZ-LOK or cheap mass made types with a thread on the outside hold much better.

The well nuts are for driver isolation and there aren't many options when you want that. Torqueing the bolts in a specific way is probably a good solution to deal with the need for a complaint mounting. It doesn't seem bulletproof though when international shipping is almost a foregone conclusion. Being good enough to design a great speaker is one skill that Alan has. Making the speaker perform that well and be tough enough to survive anything in it's life is harder. Even the best manufacturers have unexpected failures, it's how they deal with them that separates the good from the bad.

For $4K is it unreasonable to expect the use of real solid wood cabinet enclosure versus low cost MDF ?
Given the rounding on the corners in the design getting a high quality paint finish is really hard on most other materials. To find anyone in Australia to paint to that standard is expensive especially for small production runs.
 

Massimo

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Driver resonance is evident in every test for speakers that use this Purifi driver including their very own SPK5 design. See ASR review below. The peak at around 380Hz is driver resonance not port resonance.


Purifi has staked their reputation on low distortion in their products and I would probably avoid buying any speakers that use this Purifi driver until they resolve this flaw.

 

restorer-john

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Insert nuts are great, funnily enough though, of all the types available the version in your image are the worst kind for longevity in MDF. They separate the MDF into layers which can fail, at least that is my experience with them. The expensive EZ-LOK or cheap mass made types with a thread on the outside hold much better.

Insert nuts come in a large variety of course. I spent a decade with the largest manufacturer of RTA furniture in the southern hemisphere at the time, where our MDF was arguably some of the best on the planet. All E0 from sustainable pine plantations in NZ. No poor quality Chinese board like everyone uses these days. Insert nuts, combined with superior board, all CNC routed holes and alloy thread connecting rods, meant board delaminating or separation just didn't happen.

Obviously, people with cordless drills and too much torque would cause troble, but mostly, you'd shear off connecting rods before pulling out an insert nut.

Insert nuts (like the flanged one pictured) can also be inserted from the rear of the board and that prevents the issue you mentioned as the board is then pulled together as the torque is increased.

At the end of the day, there has been more suitable mounts for large/heavy loudspeaker basket rims to timber cabinets for the best part of a century. Spiked t-nuts into the rear of the board, with a suitable compliant gasket under the driver rim is better for consistency, resistance to transport degradation and long term secuity of the mount itself.

Funny thing about the Purifi driver, the magnet assembly mass and total driver mass is not quoted in the spec sheet.



iu
 
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fluid

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Insert nuts (like the flanged one pictured) can also be inserted from the rear of the board and that prevents the issue you mentioned as the board is then pulled together as the torque is increased.
I'm not sure why anyone would mount those another way in a speaker but someone probably has. Fail was a bad word as I didn't mean that the insert would pull out.
Over time in drivers with significant excursion those type can work loose more easily due to how they cut into the MDF. Good quality MDF, the right size hole cut with a CNC would all help to make it less likely but as there is almost no price difference (for the non fancy ones) I choose the thread type.
 

dualazmak

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Insert nuts come in a large variety of course. I spent a decade with the largest manufacturer of RTA furniture in the southern hemisphere at the time, where our MDF was arguably some of the best on the planet. All E0 from sustainable pine plantations in NZ. No poor quality Chinese board like everyone uses these days. Insert nuts, combined with superior board, all CNC routed holes and alloy thread connecting rods, meant board delaminating or separation just didn't happen.

Obviously, people with cordless drills and too much torque would cause troble, but mostly, you'd shear off connecting rods before pulling out an insert nut.

Insert nuts (like the flanged one pictured) can also be inserted from the rear of the board and that prevents the issue you mentioned as the board is then pulled together as the torque is increased.

At the end of the day, there has been more suitable mounts for large/heavy loudspeaker basket rims to timber cabinets for the best part of a century. Spiked t-nuts into the rear of the board, with a suitable compliant gasket under the driver rim is better for consistency, resistance to transport degradation and long term secuity of the mount itself.

Funny thing about the Purifi driver, the magnet assembly mass and total driver mass is not quoted in the spec sheet.



iu

And we should not forget using spring washers together with the fixing bolts...
 

restorer-john

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And we should not forget using spring washers together with the fixing bolts...

You would have seen plenty of those under your Yamaha NS-1000/1000M/1000X/2000 etc driver screws. Yamaha had lovely JIS #2 size head machine threads, captive flat washers and spring washers going into rear mounted insert threaded nuts.

I've sheared a few of those soft screws due to the fact some adhesives got into the threads by mistake in the factory and set like stone or the adhesives corroded the threads in situ after several decades! Normally, you can wick some acetone down threadlocked shafts to soften the glue residue. I think they were a type of torque-to-yield screw as they are considerably softer than most Japanese speaker mount machine screws. Plenty of people have changed the screws to hex SS as it looks better.
 

tuga

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@Nuyes
Thanks for all the information and data!

Controversy aside, what is shown is that, even the smallest things (amount of filling, gap in the binding posts, uneven seal between waveguide and tweeter, loose cables, etc.) can -substantially- affect the performance of a speaker, even if its built with the very best parts (Purifi components and beryllium tweeter).

Wait, so some of that GR Research guy's modifications might actually improve performance? :oops:
 

dualazmak

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You would have seen plenty of those under your Yamaha NS-1000/1000M/1000X/2000 etc driver screws. Yamaha had lovely JIS #2 size head machine threads, captive flat washers and spring washers going into rear mounted insert threaded nuts.

I've sheared a few of those soft screws due to the fact some adhesives got into the threads by mistake in the factory and set like stone or the adhesives corroded the threads in situ after several decades! Normally, you can wick some acetone down threadlocked shafts to soften the glue residue. I think they were a type of torque-to-yield screw as they are considerably softer than most Japanese speaker mount machine screws. Plenty of people have changed the screws to hex SS as it looks better.

Yes, indeed. I periodically check and tighten (if needed) all the bolts/screws of my NS-1000 including the back SP terminal panel and my "dummy not in use" attenuators. Fortunately, in my setup, all of them are still healthy, stain-free, and in good shape!

I agree with you Yamaha NS-1000/1000M/1000X/2000/10000 are very well designed, well QC-ed, well durable speakers.
 

Rick Sykora

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Driver resonance is evident in every test for speakers that use this Purifi driver including their very own SPK5 design. See ASR review below. The peak at around 380Hz is driver resonance not port resonance.

While there may be a driver resonance in Purifi driver, there is definitely a port resonance. It shows up in the modeling of the SPK5 in Bassbox Pro. See here...

1656845564664.png


Purifi has staked their reputation on low distortion in their products and I would probably avoid buying any speakers that use this Purifi driver until they resolve this flaw.


This seems a bit strong a call considering that this resonance is in one version of this driver and is not even clearly audible. Purifi's focus has been on IMD rather than HD. Not saying they should not try to improve but would avoid sacrificing the good on the altar of some notion of perfection (that does not exist in this domain).
 

restorer-john

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While there may be a driver resonance in Purifi driver, there is definitely a port resonance. It shows up in the modeling of the SPK5 in Bassbox Pro. See here...

View attachment 216154



This seems a bit strong a call considering that this resonance is in one version of this driver and is not even clearly audible. Purifi's focus has been on IMD rather than HD. Not saying they should not try to improve but would avoid sacrificing the good on the altar of some notion of perfection (that does not exist in this domain).

With the utmost respect @Rick Sykora , if resonances or 'blips' on the impedance curve are picked up, why on earth aren't people zooming in with a linear sweep centralized around the problem frequency/ies? I'm genuinely asking.

Whenever I found a 'resonance' issue, I just switched to a linear sweep with a start/stop and step freq to highlight and locate the problem area. Amir's sweeps are log, log and more log. As the frequency goes up, those aberrations become less and less illuminating.
 

Rick Sykora

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With the utmost respect @Rick Sykora , if resonances or 'blips' on the impedance curve are picked up, why on earth aren't people zooming in with a linear sweep centralized around the problem frequency/ies? I'm genuinely asking.

Whenever I found a 'resonance' issue, I just switched to a linear sweep with a start/stop and step freq to highlight and locate the problem area. Amir's sweeps are log, log and more log. As the frequency goes up, those aberrations become less and less illuminating.

Good point and am going to take your question as genuinely rhetorical ;)...

Cannot speak for Amir, but just likely folks are using defaults and, since our hearing is not linear, sticking to the log scale. With your vast experience, I really appreciate your feedback though and will consider for future investigations. I have emphasized previously to pay careful attention to scaling when doing analysis. For example, Toole's book states our hearing is not as sensitive to high Q resonances. Not sure what this means when I look at a graph and the scaling can make the Q appear more broad or narrow.

Anyway, probably a good topic for another thread!
 
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puppet

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Just to add ... if you look at the first page of this thread you'll see some photos of the "well" nuts installed. The rubber band should be in the hole not out the back side of it. Here the incorrectly used insert is acting more like a "toggle bolt" that isn't completely tightened up. The inserts shaft is free to move/slide in the hole .. and it will. These types of inserts have to be completely inside the hole to work as designed .. so the band grips the hole. As is ... no torque value can be achieved except with the fastener to the insert which is meaningless if the insert can move.

Think about why these are termed "well" nuts as they are used in situations where you can't get at the back side of the fastener.
 
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Prana Ferox

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For $4K is it unreasonable to expect the use of real solid wood cabinet enclosure versus low cost MDF ? These are bookshelves right? Is that not reasonable in today’s market? At $2k per ? Honest question here.

All things considered, real wood is about the worst possible wood product to build your speaker cabinet. It is inconsistent in density, and changes in density and dimension in unpredictable ways over time and with ambient temp/humidity conditions. Furniture-derived methods to address this (i.e. let the parts slide around in relation to each other) tend to be detrimental to the enclosure of the speaker cabinet.

A non-trash ply or quality MDF / HDF engineered product are simply better, better to build with, better over time. You can get fancy with veneers.
 
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