Complaint thread about speaker measurements

[Frank Dernie]

I would say no, it's Chinese... but that would be catty at best and in very poor taste at worst.
https://www.soundstagehifi.com/index.php/equipment-reviews/557-kef-ls50-loudspeakers

Yes, the company is Chinese owned and the speakers (maybe all) are made in China but they are still designed in the UK by a team led by Jack Oclee-Brown.

 

[thewas]

Yes, the company is Chinese owned and the speakers (maybe all) are made in China but they are still designed in the UK by a team led by Jack Oclee-Brown.

Not entirely correct, KEF is owned since almost 30 years now by GP Acoustics, a member of the Hong Kong-based Gold Peak Group (known from the batteries) and some high end models like the Blades are still assembled in the famous Maidstone plant where also the design and engineering team is located.

 

[mhardy6647]

As posted above, they are indeed manufactured in China and KEF is Chinese-owned -- but -- I absolutely don't doubt that the LS50s were designed in the UK.
I just thought the earlier (implied) point on the internal bracing's non BBC-monitorly-ness was amusing, well-taken, and potentially explainable.

'twas naught but a tasteless attempt on my part at humor in the global era

 

[Biblob]

It depends what you are trying to achieve. If you just think stiffer is better, as most engineers not used to considering dynamics do, and you don't mind a lot of small area panels with relatively high resonant frequencies this is spot on.
If you want to make the radiation less and at frequencies one's ear is less sensitive to then maybe not, though it could be, analysis would show whether it is or not.
The only way to know is to do an FE analysis and calculate the radiation from the cabinet. Which the engineering type speaker designers have been doing for decades, though many companies take what in motor racing we used to call the "hairy-arsed" engineering approach which is a bit hit and miss.

Is ie possible for a amateur hobbyist to do these simulations? Or would it only be possible with expensive software etc.? I'm interested in this design philosophy because all I have ever read is about to make box as stiff as possible by using a lot of bracing and using constrained layer damping.

 

[pma]

I think it might be interesting to share methods of measurements of cabinet resonances, plus some examples. We may speak about design approaches, but I am sure that results count.

 

[Deleted member 4987]

After I bought my Harbeth P3esrs ( in rosewood) the dealer informed me that this was a good choice as they sounded better than the other finishes. I hadn't thought about it today, wonder if there was a thin veneer of truth in this story.

 

[Rick Sykora]

I think it might be interesting to share methods of measurements of cabinet resonances, plus some examples. We may speak about design approaches, but I am sure that results count.

This is a great point as I noticed the discussion moving away from the intent of this thread. There is an existing thread to talk about speaker measurement and I just created one to discuss cabinet design topics.

 

[stevenswall]

Although to tell the truth, anyone can hear their inherent hiss and no one denies it, or do some? Its one of the prices to pay for paying much less compared to a Genelec, Neumann etc.


That has less to do with being 2 way speaker but being vertically a non coincident sound source, so it usually happens also on 3 or more way non-coaxial speakers. The advantage on the KH80 and the Revel C52 that it doesn't appear much is that they use small mid drivers (which can be crossed also higher), so a non-coaxial speaker with larger mid(-woofers) will always have it more dominant.

By the way the Genelec 8260 is discontinued now and officially replaced by the 8361.

Some deny the hiss, even though it's recorded on video, and others say they can't hear it in person: "I listened to the second review with my Etymotic ER4SR's at high volume - could not hear any speaker noise" https://www.audiosciencereview.com/...weeter-monitors-first-impressions.9874/page-2 Post #25

$100 Harman Kardon Soundsticks don't hiss as much, so to me it's not about price and just comes off as lazy.

Thanks for the clarification on the Neumann KH80... Unfortunate that it's just because they use a small woofer and can't go as low. I figured maybe there was such thing as an actually good two way that wasn't coaxial. Haven't seen the Reven C52 measurements.

The 8260 is indeed discontinued, and by their own frequency response figures, the 8361 is both less accurate and less extended in the bass... That's part of why I bought the 8260: It was an engineering marvel, and is the best in my eyes, rather than the newest, which gives up on a ridgeless/minimul diffraction coaxial, flat frequency response, and bass extension. Perhaps they will have an upgrade in a few years when they redesign the excellent 8000 series and do something with dual opposing woofers like Devialet does, and get the extension down into the teens, free field.

On a positive note, the 8361 on some W371 stands would probably be my favorite sound system in the world, albeit approaching and eye watering (for me) $30,000 before room treatment. (I'd literally feed it from the optical output from a Chromecast fed to a MiniDSP AES/EBU model.)

 

[Frank Dernie]

Is ie possible for a amateur hobbyist to do these simulations? Or would it only be possible with expensive software etc.? I'm interested in this design philosophy because all I have ever read is about to make box as stiff as possible by using a lot of bracing and using constrained layer damping.

I would say it is beyond the capability of the DIYer unless you are a Finite Element specialist and have access to the programmes.
I gave up DIY speakers since I do not have the resource to design and make a better cabinet.
Some sort of constrained layer damping will probably be better than stiffening the cabinet on a "Knife-and-Fork it" basis.

 

[Frank Dernie]

As posted above, they are indeed manufactured in China and KEF is Chinese-owned -- but -- I absolutely don't doubt that the LS50s were designed in the UK.
I just thought the earlier (implied) point on the internal bracing's non BBC-monitorly-ness was amusing, well-taken, and potentially explainable.

'twas naught but a tasteless attempt on my part at humor in the global era

Did you real the paper I linked?
It may well have been a humorous post but the paper explains how they went about making a lossy cabinet originally and how, 50 years later, they did it using computer modelling instead.
I found it an interesting read IMO, it is a very modern BBC philosophy type speaker.

 

[Juhazi]

Yes I agree with Frank about the aim for lossy walls in LS50. Putty between panels and frame must work. But the overall construction of LS50 is so far from the BBC/Harbeth school that explanation sounds more marketing to me.

Thick MDF walls with bracing anyway vibrate so minimally, that mode frequency is irrelevant. Plywood, solid wood, MDF, particle board, aluminium, steel, plastics, composites etc all have different characteristics, but thickness is very important too. Panel dimensions, curving, sandwich, bitumen pads etc. as well .

Laser interferometer scanning is the way to test cabinet vibrations and that is actually really used by some manufacturers. like KEF.
http://www.aes.org/e-lib/browse.cfm?elib=5805
https://www.finkteam.com/borg-cabinet/

 

[Blumlein 88]

This is a Magico cabinet, but I've done the same thing as DIY with a friend. Layers glued together. We used inexpensive wood or even thicker layers of MDF. You can with care and time do this with a jig saw. When doing with MDF we also angle each cut and could curve the enclosure top to bottom as well as the two dimensions shown here. We also built some layered like this putting threaded rod through top to bottom. You let the bottom be feet, and clamped it all together with lots of force using a metal top and bottom plate to spread the load over wood. Cover the top of the rod with a decorative wood piece.

This was heavy, and mostly impractical as a commercial design. It made for one heck of a stiff and damped cabinet. We were crazy to do something this labor intensive, but that is one advantage a DIY has. Now with less expensive CNC setups you could program it and knock it out in layers pretty quickly.

For lighter designs we'd use 2x3 and 2x4 to build a lattice frame, cover with thin wood. We'd attach the wood with permatex and screws. Based upon the idea the soft adhesive and many screw joints would damp and dissipate energy. We'd didn't have any way to really design it for best results, but results were pretty good. I guess closer to Harbeth (and BBC) ideas.

 

[Doodski]

This is a Magico cabinet, but I've done the same thing as DIY with a friend. Layers glued together. We used inexpensive wood or even thicker layers of MDF. You can with care and time do this with a jig saw. When doing with MDF we also angle each cut and could curve the enclosure top to bottom as well as the two dimensions shown here. We also built some layered like this putting threaded rod through top to bottom. You let the bottom be feet, and clamped it all together with lots of force using a metal top and bottom plate to spread the load over wood. Cover the top of the rod with a decorative wood piece.

This was heavy, and mostly impractical as a commercial design. It made for one heck of a stiff and damped cabinet. We were crazy to do something this labor intensive, but that is one advantage a DIY has. Now with less expensive CNC setups you could program it and knock it out in layers pretty quickly.

For lighter designs we'd use 2x3 and 2x4 to build a lattice frame, cover with thin wood. We'd attach the wood with permatex and screws. Based upon the idea the soft adhesive and many screw joints would damp and dissipate energy. We'd didn't have any way to really design it for best results, but results were pretty good. I guess closer to Harbeth (and BBC) ideas.

View attachment 48653

View attachment 48654

Very KewL >@^_*@<

 

[thewas]

The 8260 is indeed discontinued, and by their own frequency response figures, the 8361 is both less accurate and less extended in the bass... That's part of why I bought the 8260: It was an engineering marvel, and is the best in my eyes, rather than the newest, which gives up on a ridgeless/minimul diffraction coaxial, flat frequency response, and bass extension.

The 8361 has a smoother vertical directivity and sound power as well has a higher max SPL than the 8260 it replaced, everything is a compromise.

 

[stevenswall]

The 8361 has a smoother vertical directivity and sound power as well has a higher max SPL than the 8260 it replaced, everything is a compromise.

Yep. It's louder and has better vertical directivity. The only tradeoff I see is cost: I'm sure they could get it to +/-1dB instead of 1.5dB, and add rear woofers or seal it and have a massive rear driver used like Dutch & Dutch 8C. To me it seems they are prioritizing volume and are okay with the tradeoffs. Volume isn't much of a concern for me, and I've never heard any review of studio monitors say "they don't go loud enough."

Just need $10k burning a hole in my pocket to have them both tested and see what the acceptance score would be. Hopefully the calculation doesn't take into account "this goes ultra stupid mind numbing loud so it's better" compared to "this only goes to painful levels."

 

[thewas]

$100 Harman Kardon Soundsticks don't hiss as much, so to me it's not about price and just comes off as lazy.

Here in Germany they cost more than a pair of JBL 305 (!) and they cannot be compared directly as they have only 10W amp (which could be implemented even in Class AB) and a direct volume control on them, while active loudspeakers are always "turned to max" and you regulate the volume from the source. Trust me, the engineers of JBL, Kali and similar low price but good acoustic quality monitors are neither dumb or lazy, but using some "hiss free" electronics would raise their price significantly which could mean significant sale loss in such a hard market segment.

 

[stevenswall]

The 305 has volume controls on the back... And yes, it could also be explained by them not prioritizing things I care about like not hissing and bass extension rather than just being lazy or not testing the product. (Apple has done the latter though with the iPhone 4 antennae debacle.)

Note: The Soundsticks are a total of 40 watts, 10 to each satellite, and 20 for the woofer. Also better cabinet geometry and aesthetics. Kind of want to hear the GLA55 ones to see how good the bass is, especially after hearing a Phantom and how low something small like that can go.

 

[thewas]

The 305 has volume controls on the back...

Its not the same thing, on active monitors you use that level control only once for different level sources like RCA vs. XLR, not to regulate the volume level which you do through your sound interface, some even only have a switch with only 2 settings.

Note: The Soundsticks are a total of 40 watts, 10 to each satellite, and 20 for the woofer.

Yes and the 10 W of the satellite have to be compared with the 40W of the tweeter of a Kali or JBL.

 

[Frank Dernie]

Yes I agree with Frank about the aim for lossy walls in LS50. Putty between panels and frame must work. But the overall construction of LS50 is so far from the BBC/Harbeth school that explanation sounds more marketing to me.

I am surprised.
As an old engineer who worked from the early 70s and retired in 2009 I know it is entirely consistent with the way engineering design and construction methods have advanced.
Back in the 70s almost everything was tested using prototypes (because computer modelling was not yet available) but conceived (the good ones anyway) based on an understanding of the first principles of the physics.
The BBC found that a lossy cabinet gave the least coloured sound in their listening tests and proceeded to build prototypes to achieve it.
Fast forward to modern times and making a lossy cabinet using FE techniques allows far more possibilities to be investigated than making prototypes and using the methods of today to achieve the goals set in the 1970s to achieve a lossy cabinet seems 100% logical and sensible to me, certainly what I have done in my career as methods and materials have advanced. KEF are by no means the only manufacturer using lossy cabinets to produce superb sounding speakers today.

I designed my first Formula 1 car when I was 26 using the best techniques I could find then. The idea of doing the same car today is quite laughable, despite the goals being exactly the same.
The KEF paper makes perfect sense to me, though I realise it is the KEF USA marketing site where it is most easily found

 

[pma]

Back in the 70s almost everything was tested using prototypes (because computer modelling was not yet available) but conceived (the good ones anyway) based on an understanding of the first principles of the physics.
The BBC found that a lossy cabinet gave the least coloured sound in their listening tests and proceeded to build prototypes to achieve it.

So the subjective listening tests made by BBC sometimes in the 70's are considered as a proof of that design approach even now in 2020. This is a bit surprising, to me.