Things to Come

[kkantor]

Tom,

Two boxes have arrived at Tymphany. I haven't been there to open them, but I hear they are in good shape. I hope I can get to work with them this weekend, otherwise there will be a couple of weeks delay. Thanks!

[tysontom]

>Tom,

>

>Two boxes have arrived at Tymphany. I haven't been there to

>open them, but I hear they are in good shape. I hope I can

>get to work with them this weekend, otherwise there will be a

>couple of weeks delay. Thanks!

>

>

Ken,

I apologize for not noticing your thread; I've been gone quite a bit here lately, and had it not been for someone else mentioning it, I would have missed it altogether. The big box is an AR-3 enclosure without drivers, modified for woofer testing. The second box is a Tonegen flat-side AR replacement woofer for test. Others to follow once I get back home and get my act together.

--Tom Tyson

[kkantor]

Tom,

I have been going back and forth in my mind as to whether I should take the time to repeat the Klippel work. Did you think it added much to the process? Otherwise, I will do SS parameters and in-box response.

[tysontom]

>Tom,

>

>I have been going back and forth in my mind as to whether I

>should take the time to repeat the Klippel work. Did you

>think it added much to the process? Otherwise, I will do SS

>parameters and in-box response.

>

>

If you are talking about repeating the entire process, I would hope not, mainly due to the time and effort required. Perhaps a ramdom test or two to corroborate the two methods. The first Klippel Analysis work you did seemed to be long, detaied and time-consuming, even though automated for the most part; obviously you could not do too much of this sort of thing.

I am sending a couple more woofers of the old variety. I meant to get them out to you last week but could not get it together. You should have the Tonegen woofer now, which is the current service-replacement woofer for the original 200003-0/1210003-0 woofer. There is question as to how it compares to the original.

--Tom Tyson

[Guest Bret]

>There is question as to how it compares to the original.<

Thank you for sending these, Tom. We owe you. And thank you, Ken, for continuing with these measurements despite your schedule.

The central question I was hoping to help answer with the drivers I sent was "how do these compare with the original." Unfortunately I wasn't able to produce a "base-line" against which to judge.

Even though I think we were able to learn that "all repairs are not equal" the data was only useful in a relative sense.

It looks like what you guys are working-on now will get us good, hard information. I look forward to more results from Ken with highly practical application thanks to your providing a standard.

The only "big picture" question this will leave open for interpretation is whether using the "best" woofer in a design other than the one it was originally a part of is "being untrue" to the original cabinet (not to the extent of changing to a Dynaudio midrange driver, but along those lines).

Bret

[tysontom]

>

>Thank you for sending these, Tom. We owe you. And thank you,

>Ken, for continuing with these measurements despite your

>schedule.

>

I was pleased to send the cabinet and the woofer to Ken; other woofers to follow, perhaps this week. The hard part is for Ken, and I would not want him to spin through additional measurements on all of the woofers again. The one thing I did want to do was to provide a known quantity, a test-bed 1.7 cu. ft. AR-3 enclosure in which Ken could test some woofers -- hopefully into 2-Pi steradians (180-degree solid angle), and then compare those curves to the original curves done by Ed Villchur, Roy Allison, et al at AR back in the 60s. Those curves are repeatable, and this would be our best hope for determining if the rebuilt drivers are replicating the originals, more-or-less.

>The central question I was hoping to help answer with the

>drivers I sent was "how do these compare with the original."

>Unfortunately I wasn't able to produce a "base-line" against

>which to judge.

>

This was the idea behind the original drivers and original enclosure.

>It looks like what you guys are working-on now will get us

>good, hard information. I look forward to more results from

>Ken with highly practical application thanks to your providing

>a standard.

>

>The only "big picture" question this will leave open for

>interpretation is whether using the "best" woofer in a design

>other than the one it was originally a part of is "being

>untrue" to the original cabinet (not to the extent of changing

>to a Dynaudio midrange driver, but along those lines).

>

This was the feeling I had about using the NHT 3.3 NHT1259 woofer (Ken's design) in a pair of AR-303As: that outstanding woofer would be excellent in terms of distortion and bass extension, but it would require a crossover change to get everything aligned properly, and the NHT1259 probably is not as well suited to the upper bass as the original woofer. I decided against the idea in the end.

--Tom Tyson

[kkantor]

A tech did all the Klippel-ing, so I am somewhat at the mercy of his spare time for that aspect of the testing. At a minimum, I need him to train me on the proper set-up.

The rest of the testing is not a problem for me, though I don't have a proper 2-pi chamber. I'll think about the best way to mimic the V/A conditions. NHT would probably let me use their chamber to shoot a few curves. I originally brought that chamber out from Canton, and it was in Norwood before that. So, who knows, maybe it has some of the original DNA...

[kkantor]

In my opinion, speakers are very holistic devices, and once you start to try and improve one part, you wind up altering the inter-relationship of almost everything.

Many hobbyists view speaker design as a matter of selecting and matching the best drivers, putting in the best crossover parts, etc. That's like a chef who purees a pound of excellent tomatos with a clove of nice fresh garlic, but never stops to taste the sauce as it cooks together. No matter how good the ingredients, no matter how many years in the kitchen, you will rarely produce a really good meal on autopilot.

What I am trying to say is that it is never the a priori planning that makes a consumate speaker, nor is it the raw quality of the individual components. It is the listening and refinement and ongoing judgement. For this reason, it is tricky to try and improve one part of a successful design, especially on paper.

I'm not saying it can't be done, of course it can be. But it is hard to do without losing the nature of the original design. This is evident in that even the most skillful professionals often fail when trying to improve a SuperSound 1 into a SuperSound 1.1.

[tysontom]

>A tech did all the Klippel-ing, so I am somewhat at the mercy

>of his spare time for that aspect of the testing. At a

>minimum, I need him to train me on the proper set-up.

>

>The rest of the testing is not a problem for me, though I

>don't have a proper 2-pi chamber. I'll think about the best

>way to mimic the V/A conditions. NHT would probably let me

>use their chamber to shoot a few curves. I originally brought

>that chamber out from Canton, and it was in Norwood before

>that. So, who knows, maybe it has some of the original

>DNA...

Do you have a back yard and a shovel? Just kidding, of course, but this was the method originally used to test the AR-1, and later woofers. 2-Pi "field-testing," literally, with the speaker in a hole flush with the top of the ground, facing skyward of course -- RIP.

I saw that old AR chamber, along with the old AR magnetizer, during my visit with Bill Bush at NHT three or so years ago; I have great pictures. That had to be quite a chore to ship that chamber to California, even if in parts. I guess my question would be if the chamber is anechoic at low frequencies, and therefore truly appropriate for low-frequency testing.

--Tom Tyson