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Should we (I) get into speaker testing & measurement
- Thread starter amirm
- Start date
watchnerd
Grand Contributor
Like have Amir drive around the country in a camper van to roll up to people's houses with the Klippel?
Nope, the room is irrelevant, the Klippel measurement is going to provide an anechoic style measurement.
It measures the output of the speaker, it doesn't matter how the output is achieved.
OP
- Thread Starter
- #647
Before we worry about a Room Bob, we need to see how the speaker creates the signal that interacts with the room. If that has certain deficiencies, you cannot fix it with any kind of DSP. The analysis of the measurement data will let us determine what can be fixed, and what cannot.
Wide variety of loudspeaker contructions makes it very difficult to determine how a loudspeaker performs in-room. Then add wide variety of rooms and placements... 3D measurement data is available ony for small number of speakers, and eg. Princeton 3D3A lab reports dont give any listening impressions of guess/estimate about how those speakers sound in a room.
I recently read a Finnish hifi magazine test of 11 midprice floorstanders, there was only room response measurements which apply for that room and placement, but graps and listening impressions matched well!
Biggest differencies in in-room audible performance are with bass extension and level, and directivity and level of high frequencies. Then we have people with different preference of how said features should be like! Some like boomy bass and sharp imaging, others low extension without bumps and airy diffuse soundfield.
What kind of sound would you expect to get from these loudspeakers, in a small well damped room vs. a large and highly reflective modern living room?
ps. I was only thinking of typical mid-price hifi speakers. If we expand the view to soundbars, portable speakers, studio monitors,PA mains, installation speakers or high-end extravaganza we get more deeply in trouble.
I recently read a Finnish hifi magazine test of 11 midprice floorstanders, there was only room response measurements which apply for that room and placement, but graps and listening impressions matched well!
Biggest differencies in in-room audible performance are with bass extension and level, and directivity and level of high frequencies. Then we have people with different preference of how said features should be like! Some like boomy bass and sharp imaging, others low extension without bumps and airy diffuse soundfield.
What kind of sound would you expect to get from these loudspeakers, in a small well damped room vs. a large and highly reflective modern living room?
ps. I was only thinking of typical mid-price hifi speakers. If we expand the view to soundbars, portable speakers, studio monitors,PA mains, installation speakers or high-end extravaganza we get more deeply in trouble.
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I absolutely agree and Aaron was dead on in his reply.
An idea I just thought up was reaching out to knowledgable, dedicated local DIYers for a Klippel timeshare. They would be inclined to pay more I'd imagine - a 1-3k DIYer measuring rig is not unheard of (eg. Smith and Larson equipment) and paying the same amount for vastly better automated measurements would allow them to iterate much faster. It would increase the diversity of the measurement database, keeps throughput high, while also reducing your own load.
OP
- Thread Starter
- #651
How do you timeshare this? It is not portable and assembly and disassembly takes days. I think the total package weighs 300 pounds or something.
You didn't get one for Christmas?
OP
- Thread Starter
- #653
No, I got a note that it would have gotten stuck in the chimney....
Dumb question - Some manufacturers (Harman?) have measured their speakers right? If they've published their measurements and we trust them, why not everyone buy their speakers and we can call it a wrap? I will gladly take the $70K check now. Thanks.
OP
- Thread Starter
- #655
Oddly they don't publish their measurements. That aside, speakers can be a personal thing with looks, price points, dealers, support, distribution, etc. If I want a $300 bookshelf speaker there is no option in Revel line.
Several reasons:
- Virtually every reputable speaker maker measures its speakers, very few of them publish their measurements. Harman, for all its research and contributions, only publishes measurements sparingly and they're usually not easy to find.
- On that note, I've seen plenty of speakers that measure great for which no manufacturer-sourced measurements are available. Sometimes I'll measure a speaker myself, find fantastic results, and scratch my head at why a manufacturer doesn't publish measurements themselves.
- When measurements are available, they are usually incomplete, don't include enough angles, are overly smoothed, use weird scaling, etc.
- On the topic of this thread, using one rig to measure multiple speakers helps ensure consistency in comparisons. Often we here are comparing speakers measured by different people/companies. While good measurements should be replicable, and it's rate to see major disagreement among speakers measured by different people, it's not ideal to compare across sources.
- For the rare occasions measurements are available, it's important to be able to replicate them.
- Harman speakers are good, but they're not the only ones making good speakers, obviously. Some companies can outdo Harman at their own game at a given price point.
- Aesthetics matter. Maybe other companies make prettier speakers; whatever floats your boat. I'm not a huge fan of most JBL or Revel designs, for instance.
- There are different ways of having "good" measurements. Some people like wide directivity, others like narrow directivity. Some speakers work better in some rooms than others, etc. Measurements help you figure that out.
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Dave Zan
Active Member
Hi Amir
I put in quite a bit of time and effort in the "Klippel Scanner on the cheap" thread in DIYaudio and now member NTK in this forum looks like he has an excellent idea of the maths and code required.
All the details of the Klippel scanner are not yet worked out but certainly a usable foundation.
As well as the maths I also have an idea for the mechanics that should be far more portable and less massive.
Is there any way we could crowd-source you a Klippel clone?
I have a reasonable machine shop - tool-room lathe and the usual.
I would be ready to put in machine hours as a contribution to ASR and I have some materials to donate (carbon fibre mainly).
We have some members with expertise in CNC for the motion control and plenty of expertise in the electronics.
Main problem* I see is that I am in Australia, makes it inconvenient to ship sub assemblies to/from the US based members.
So maybe the integration assembly needs to be done near you.
It is rather ambitious, does it sound possible?
Other option is a CTA 2034 measurement system in the far-field.
Simpler but takes more space, how much do you have?
Best wishes
David
*Actually the main problem at the moment is that my workshop is about 50 C/ 125 F and the air is unbreathable.
And I work slowly at the best of times.
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OP
- Thread Starter
- #658
Hello David. It is past midnight so let me respond more tomorrow.
For now, another DIY forum member has volunteered to build the mechanics. The issue is the software. My main signal processing contact has conflicts so can't help. Do you feel based on work that NTK has done, that you can get the full system going? As far as I recall, NTK did not tackle the field separation math, only the near field to far field expansion.
For now, another DIY forum member has volunteered to build the mechanics. The issue is the software. My main signal processing contact has conflicts so can't help. Do you feel based on work that NTK has done, that you can get the full system going? As far as I recall, NTK did not tackle the field separation math, only the near field to far field expansion.
Dave Zan
Active Member
Excellent, perhaps I can at least contribute some ideas.
NTK has done the field separation, and very impressively.
He has actually written code while all I did was work on the maths.
I believe his code would do the core job.
He would be better placed than I am to add interfaces and other essential bits but I believe I could do so, especially if he advises.
I understand the author of REW measurement software is a member here too.
I always planned to use REW so it would be nice to have his advice available in case of issues in that area.
The Klippel NFS does one trick that I haven't worked out fully - that is to factor out the reflections off the speaker of the reflections from the room.
I haven't studied this too hard because it's their patented bit so it's protected even if I did work it out in detail*.
I asked NTK (does he have a real name?) his comments on it but I haven't had a response yet, probably Xmas and all.
But I think it will have minimal effect unless you try to measure a bulky speaker in a small room.
That may be an impressive stunt for Klippel to demonstrate but hardly a problem for typical use.
Best wishes
David
*Also because it looked quite difficult!
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I'd be particularly interested in using the measurements to determine the performance of vintage speakers as opposed to modern speakers.
Additionally, I think it would be interesting to compare the performance difference of these £10,000 speakers to £1000 speakers; perhaps create a metric by which to express the overall performance of a speaker. This could then be used to create some sort of price to marketing ratio or price to performance ratio to objectively assess whether the speaker is worth the price being asked for it. Not only this, but it could also be used to evaluate the effects of different design decisions and methods.
Additionally, I think it would be interesting to compare the performance difference of these £10,000 speakers to £1000 speakers; perhaps create a metric by which to express the overall performance of a speaker. This could then be used to create some sort of price to marketing ratio or price to performance ratio to objectively assess whether the speaker is worth the price being asked for it. Not only this, but it could also be used to evaluate the effects of different design decisions and methods.
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