This might be interesting!

Rip Van Woofer

Rip Van Woofer

Audioholic General
I got this email from the local audio club I recently joined, the Southeast Michigan Woofer and Tweeter Marching Society:

"...The program involves a subjective listening test of loudspeakers which will be done before the meeting at [the host's home]. The test will be blind
and randomized so that discussions about the speakers won't be possible
until the order of each set of tests is revealed. The results and the
speakers being compared will be revealed during the formal SMWTMS meeting.

"Listeners are asked to sign up for a time slot. There will be six listeners
for each hour..."

An earlier email asked for the loan of a "highly regarded" speaker to be used for the test. That's all I know! I've signed up and will report here. The program/meeting is Nov. 13.
 
Yamahaluver

Yamahaluver

Audioholic General
Could be wrong but smells like a ad campaign for some speakers to me.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
Yamahaluver said:
Could be wrong but smells like a ad campaign for some speakers to me.

How so? Why do you think this?
 
Rob Babcock

Rob Babcock

Moderator
Sounds very interesting to me. I can't see how it could really be used to advertise anything, at least not by some big company. C'mon- would B[l]ose really try to use the Southeast Michigan Woofer and Tweeter Marching Society in their ad campaigns? :rolleyes:

Speaker tests like that can be tricky. Obviously the speakers must be physically moved, lest on be in the "sweet spot" and it's tough to compare many models in the same shootout. Still, the results should be interesting- although given the very subjective nature of preferences, I wonder how relevant the results could be.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
Rip Van Woofer said:
I got this email from the local audio club I recently joined, the Southeast Michigan Woofer and Tweeter Marching Society:

"...The program involves a subjective listening test of loudspeakers which will be done before the meeting at [the host's home]. The test will be blind
and randomized so that discussions about the speakers won't be possible
until the order of each set of tests is revealed. The results and the
speakers being compared will be revealed during the formal SMWTMS meeting.

"Listeners are asked to sign up for a time slot. There will be six listeners
for each hour..."

An earlier email asked for the loan of a "highly regarded" speaker to be used for the test. That's all I know! I've signed up and will report here. The program/meeting is Nov. 13.

Sounds like fun :) Maybe it's a test of how well you know your own speaker?
Or, if it is graded, how it will come out; something like Toole has done.
 
Rip Van Woofer

Rip Van Woofer

Audioholic General
Yamahaluver said:
Could be wrong but smells like a ad campaign for some speakers to me.
I'm a cynic too but, nah, the club's been in existence for over 20 years and many are AES members with published papers - they're legit. A quick look at their bare-bones Website should suggest that they don't get any corporate swag! (And their name suggests that they don't take themselves too seriously - a big attraction for me!)

BTW, they were the main experimental subjects of David Clark's famous AES published ABX tests back in the '80s. Clark is evidently a charter member.

Anyway, unless they object for some unforeseen reason I'll tell youse all about it here after the meeting!
 
Swerd

Swerd

Audioholic Warlord
Yes it sounds like fun. At least with speakers, you can be reasonably certain that there will actually be audible differences. :D

A useful idea I got from DC 2004 DIY was that they began the speaker comparisons by listening to a 2-way with a Vifa P17 woofer and a D25 tweeter. It is common enough to be considered a "standard speaker". It allowed everyone's ears to adjust to the room acoustics and any other noticable features of the music selections or the other audio gear that were in use and would be common for the rest of the speakers.

Straining to hear differences between crossover capacitors or speaker cables can be like listening to grass growing or paint drying. I found it interesting that during the capacitor tests at DC 2004 DIY, most people thought they were hearing differences during the test. Only after the results were summed up, was it clear that there was no agreement among listeners or any common pattern that would suggest that there were audible differences in the capacitors. Imaginations were actively at work while listening to all that drying paint :p. See if you notice that phenomenon at work with the speakers. Apparently many people are unwilling to believe that this happens routinely.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
Rob Babcock said:
Still, the results should be interesting- although given the very subjective nature of preferences, I wonder how relevant the results could be.

I think it will show how much bias may enter the selection process :D
These will be behind acoustic curtains :D
Will be interesting who can pick their own speakers :)
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
Swerd said:
Yes it sounds like fun. At least with speakers, you can be reasonably certain that there will actually be audible differences. :D

A useful idea I got from DC 2004 DIY was that they began the speaker comparisons by listening to a 2-way with a Vifa P17 woofer and a D25 tweeter. It is common enough to be considered a "standard speaker". It allowed everyone's ears to adjust to the room acoustics and any other noticable features of the music selections or the other audio gear that were in use and would be common for the rest of the speakers.

Straining to hear differences between crossover capacitors or speaker cables can be like listening to grass growing or paint drying. I found it interesting that during the capacitor tests at DC 2004 DIY, most people thought they were hearing differences during the test. Only after the results were summed up, was it clear that there was no agreement among listeners or any common pattern that would suggest that there were audible differences in the capacitors. Imaginations were actively at work while listening to all that drying paint :p. See if you notice that phenomenon at work with the speakers. Apparently many people are unwilling to believe that this happens routinely.
If the speakers are behind the acoustic curtains, it will be interesting how the imaginations will work too:)

In the cap test, they should have demonstrated how people will pick out differences even when no changes are made :D
 
Swerd

Swerd

Audioholic Warlord
mtrycrafts said:
In the cap test, they should have demonstrated how people will pick out differences even when no changes are made :D
I tried hard to convince Dennis Murphy, the organizer, to do that kind of negative control test for any future cap tests. It was too late for the test that day. He answered that a negative control would only be useful if there was any result that looked like it may be positive. The results that day were 50-50, no different than random guessing. He also pointed out that negative controls would decrease the number of repetitions people could do on the real test. He was correct on both points, and still should have done a negative control. Judging by the lengthy and controversial discussions still raging on the Madisound board, there are more than a few people who cannot accept the conclusion that expensive polypropylene caps make little or no difference. If he had run the negative control, it would have been useful in flame-proofing his conclusions from the numerous critics. I wonder if he feels different about negative controls now?
 
jaxvon

jaxvon

Audioholic Ninja
Sounds cool. Judging from the pics on the site, I think it might be be a little too 'old' for me. Gotta put on a few more years before I think of joining.

Also, this is one massive horn. :eek:
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
Swerd said:
I tried hard to convince Dennis Murphy, the organizer, to do that kind of negative control test for any future cap tests. It was too late for the test that day. He answered that a negative control would only be useful if there was any result that looked like it may be positive. The results that day were 50-50, no different than random guessing. He also pointed out that negative controls would decrease the number of repetitions people could do on the real test. He was correct on both points, and still should have done a negative control. Judging by the lengthy and controversial discussions still raging on the Madisound board, there are more than a few people who cannot accept the conclusion that expensive polypropylene caps make little or no difference. If he had run the negative control, it would have been useful in flame-proofing his conclusions from the numerous critics. I wonder if he feels different about negative controls now?

If nothing else it will point out to people how easy it is for them to claim a difference when nothing changes. It is a built in human nature without an on/off switch :D

Maybe he will consider it as a demo one day ;)
 
Rip Van Woofer

Rip Van Woofer

Audioholic General
Update

Update! Yamahaluver may have been half right. The host of the meeting is an acoustical and audio consultant who -- ta daaa -- is also working on a speaker design. His thing is polar response, and he claims to have developed some sort of waveguide technology to give the most uniform polar response of any speaker extant. So maybe we're beta testing his design? Here's his Website

This is not a bad thing if he's doing an honest test of his prototype (remember, I'm guessing here -- the test may not involve his speaker at all). He is an AES guy and seems to do things the ethical way: peer-reviewed papers, patents, etc. And there's no snake oil as far as the design rationale goes: uniform polar response is generally regarded as a Good Thing. A further speculation: perhaps he wants to see if his design principle actually makes an audible difference in controlled blind listening situations? Again, a good thing assuming an honest test.

Anyway, I'll bet he has a kick-a$$ HT room!

Stay tuned. I have my listening slot time confirmed.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
Rip Van Woofer said:
Anyway, I'll bet he has a kick-a$$ HT room!

Stay tuned. I have my listening slot time confirmed.

Ask him :D

Maybe the club will have a visit there ;)
 
Rip Van Woofer

Rip Van Woofer

Audioholic General
Speaker test report

I attended and took part in the speaker test. Very interesting!

The main points:

1) The host and presenter, Earl Geddes, is a speaker designer and consultant. His interests are waveguide (horn) speakers, acoustics, and HT in general. He was demonstating and, in an informal setting, testing his new speaker design. He has been interested in understanding and solving the typical horn speaker coloration. His work, which he said parallels and builds upon the published work of others, is incorporated into the prototypes he showed us and tested. They're big honkers with 12" or 15" bass reflex woofers and a horn tweet of his own design. Yep, just a two-way for a speaker that size!

2) His horn design uses a specific taper and a specialized porous, open-cell foam plug that fits into the round horn rather like a large trumpet mute. He posits that much of the objectionable coloration results from "high-order modes" within a typical horn. My (imperfect) understanding of these modes is that they are the result of oblique reflections within the horn; analogous to the tangental (as opposed to axial) modes in rooms. (As a layperson I'm probably not the best reporter!)

3) He believes that uniform and tightly controlled polar response is a key to good speaker sound. In particular, he takes the somewhat contrarian view (at least as far as I understand it) that the ideal HT room should be quite "live" (where mid and high frequencies are concerned he seems to favor diffusion over absorption) and that the speakers should have a fairly narrow and well-controlled dispersion pattern (the latter sounds like THX, of course). His design aims for that. He showed us anechoic measurements taken every 7 degrees from on-axis to 90 degrees. Things of beauty. You know how you often see a dip in the off-axis response of most speakers in the crossover area? That was gone. And the high-frequency rolloffs off-axis were smooth and uniformly spaced. Pretty amazing for a two-way system with a large woofer.

4) The test: we listened blind to four speakers hidden behind an acoustically transparent black fabric. There were groups of six listeners for an hour each. For each group the speakers were shuffled so that speaker "A", for instance, would be different for each group (that way we coudn't compare notes around the bar!) Basically, the results were "all over the map" in his words with no unit (including his) the clear winners. I liked both his prototypes best. Tom Nousaine didn't think any of them sounded all that great. The other two speakers were a JBL 2-way studio monitor (big bass reflex woofer and horn tweeter) and a Gradient floorstanding speaker.

I gather that several similar tests under more controlled conditions were done and are presented in his AES paper, presented at the Novermber conference. The paper deals with his waveguide design. He has patented it. He also holds several other patents.

As you see from the picture, the listening conditions were less than ideal. No doubt, to my mind, the Gradient would have had better bass if it were near a wall as is the usual practice (I thought it had little bass and a too-bright top end, FWIW). But as one person told me, at least they were all equally handicapped. And the room was quite reflective.

And yes, he does look a bit like a cross between Capt. Picard and James Carville! The redeye from the flash makes the effect pretty scary, but he's a nice if somewhat serious, terse guy.

As a bribe to get us there, he offered free copies of his self-published book, "Premium Home Theater Design and Construction". It sells for $39. On quick perusal of my copy it's worth it. Good balance of theory and practical advice. The chapter on construction techinques is worth it alone! And he's big on value for your buck and death on BS and snake oil which his wife and biz partner, an experimental psychologist, calls "audio tarot". Here's a quote from the introduction that should endear him to the typical Audioholic:

I will limit my discussion to what I call high "value" designs and components. One can spend almost an unlimited amount of money on a HT, but that is not my interest here. My intent is to describe the most cost effective--the highest value--designs and components for the reader who has a limited budget, and I doubt that anyone reading this text would not.
Finally, about the club. The Southeast Michigan Woofer and Tweeter Marching Society (SMWTMS, affectionately called "Smootums") is heavy with engineers and audio pros. It's kind of a smaller version of the Boston Audio Society. One guy there was a former designer for the original DCM speaker company and worked on their Time Window line; another was a recording engineer who worked with Motown back in the day. But they made me, an average Joe with a liberal arts degree, feel welcome. As a new face I was asked to intro myself. When I told about my long absence from audio they asked if I had any old gear; they thought my old Dynaco gear was cool! Although one guy got a bit huffy with me during the speaker test because I rattled my response form a bit much for his liking!

Here is a link to Earl Geddes' Website where you can read about his work, consulting biz, and buy his book. He also has a book on transducer design. Too techy for me!

Presumably his AES paper is or soon will be available from the AES Website as a preprint or journal article.

Oh, yeah, the meeting/demo was at his house and, yes, he does have a kicka$$ HT setup in his basement. He had the Talking Heads "Stop Making Sense" concert playing on a 7.1 HTPC based front projection system so we could wander in and check it out. Freakin' awesome. And very well isolated from the rest of the house. Even from just outside the doors it was a whisper. Then you opened the doors and, whoa mama!

For sound diffusion and looks, one sidewall of the room was completely done in cultured stone!
 

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mtrycrafts

mtrycrafts

Seriously, I have no life.
Thanks for the report. Very interesting. Too bad that I still don't see the thumbnails :(

I think over time you will enjoy the club.
Don't let an individual get on you nerves. ;)
 
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