John Curl's Blowtorch preamplifier part II

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I find the hi fi evaluation to be a long careful process. I am now changing my speakers to something 'better' than the Sequerra Met 7's. They should be better since they are more than 30 times more expensive to purchase. However, I am STARTING with the same feed as I normally use for the Sequerras, to note the difference, all else being equal. It is the TV feed, not my reference feed, so it is not as clear or extended, but the speakers do make some difference. One thing that I noticed, as I did with the WATT1's, that are heavy acrylic and lead lined, is the lack of cabinet 'cry'. The Sequerras are pretty good but not as good as the Wilson's.
This is an interesting subject that gets less attention than it deserves, and it is NOT necessarily obvious as to the solution.
IF some of you will just LOOK at the GD Movie, you will see what we tried to do to make a good speaker cabinet and array, and it weighted thousands of kilos. Yet, I would not do it that way today. Why? Cabinet Q. This might be an interesting subject to discuss, there are very good articles, even in the AES, starting from 1975, in my experience.
 
However, I am STARTING with the same feed as I normally use for the Sequerras, to note the difference, all else being equal. It is the TV feed, not my reference feed, so it is not as clear or extended, but the speakers do make some difference.
One should hope so ... :)

What would be interesting, once reference feed is hooked up, and the Wilsons totally grooved in ... is to quickly switch back to the Sequerras on that same feed, changing nothing else ... and estimating, judging what's 'lost' ...
 
didn't pass the test I guess

I own both, Scott. What do you have to compare with?
Everybody, I learned about the importance of cabinet resonance from D.A. Barlow, who I met at the London, AES in 1975. He had the same problems then (in 1975) as I have here today.

guess the 'learnin' from '75 wasn't 'takin' if'n your still havin' the problim today.... 38 years later???

What happened?
 
From what I have read, it is the DAMPING of the loudspeaker cabinet that is the real problem that is not easily addressed.
This what Barlow first put forward.
I have done more than my share of speaker boxes, and I have seen some pretty lousy ones that I have had to live with.
I have found that only living with a 'good' speaker cabinet, then losing it, and then trying to get by with a modest substitute, makes it very important. We are all used to cheap and modestly made speakers that have cabinets that put out all kinds of stuff, so we usually accept it, unless we hear a 'buzz' or rattle or something.
 
instinctivrly, I tend to favour the approach of the cabinet bring rock solid with only the speakers & air vibrating, but others claim that allowing the cabinet to move in a controlled ( damped ) way gives a more natural sound.

It's the same issue as choosing high distortion tube amp to mask fatiguing details to get more enjoyment.

If you want 0.0001% thd, you have to work much harder to get to enjoyable sound.

More precise analogy, actually equivalent issue, is the use of stiff cone. Theoretically correct, but isn't paper flex distortion more enjoyable than stiff cone ones?

Now when we talk about high frequency, I believe that people have underestimated the audible fatiguing effect of HF distortion!

Regarding box resonance, it is not yet possible to arrive at optimum metrics such as what is the frequency, the Q, or the maximum time for the ringing for a specific design.

Just like cones, intuitively it is best to use sandwich Panel (stiffer on the outside). But that's only for cost no object projects.

In less than perfect design, yes, rigid box tends to be less enjoyable, especially if your system or crossover cannot reproduce the low level reverberation. Of course, when everything perfect, rigid one will give bass detail and more correct pitch.

As for THD, I accept 0.02%. But equally so at 20kHz. So not a tube amp. As for cones, I accept stiff cones. As for enclosure I cannot decide but tend to choose rigid one. At low volume I prefer non rigid one but the box tends to "collapse" at high spl.
 
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When I first met D.A. Barlow, it was at the 1975 London AES Convention. He told me then that he was having a lot of trouble presenting his paper and getting it published, because several popular loudspeaker manufacturers did not like what he had to say about cabinet resonance.
I find much the same thing about my 'observations' today. '-)
Jay, I learned from your input. I think you are on the right track.
 
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When I first met D.A. Barlow, it was at the 1975 London AES Convention. He told me then that he was having a lot of trouble presenting his paper and getting it published....

That seems a bit odd since Barlow's paper was given and published by AES in 1975. Iverson's 1973 paper anticipated much of this as well. Briggs (1962) seems to be the grand-daddy of the genre.
 
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Tuning the cabinet panels for "better sound" is hardly new. The 1/4" Masonite rear panel on many '70s and '80s cheap speakers was selected to warm up the balance and save some $$. There have even been patents for boxes with panels designed to move with the sound. However as pleasing as these extra sounds may be they would not ever be a part of the recorded sound.
 
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