IMF Transmission Line Stuffing?

[marcmorin]

I do not have confidence on his audio judgement if one considers the AR-XA turntable to be a "top notch" turntable. in 1964, Edgar Villchur designed a low-cost ($78) belt-drive turntable with a cast aluminum 3.3 lb (1.5 kg) turntable platter suspended with a T-bar sub-chassis to reduced acoustic feedback. He used a 24-pole hysteresis-synchronous, permanent magnet Hurst AC motor propelled the platter via a precision ground rubber belt to produce very low wow and flutter. But Edgar cannot afford to put a high quality bearing on the design. As a result, the AR turntable will sound excellent for a few months, but starts deteriorating when its cheap bearing develops play. The problem was easy to detect and very audiable.

The Minneapolis area was an audio hot bed in the 1970's. When I looked for something better than the Dual 1219, I first looked at the AR because of all the noise about it. But I was pointed to the right direction by one of the most respect audio Boutique owner in Minneapolis who taught me how to distinguish the sound of the AR vs. a Thorens TD-160. I never look back since.

Anyone who has question about the importance of the turntable bearing can find the answer in early Linn Sondek LP12 product borchure.

Gary A. Galo wrote a series of AR mod articles for Audio Amateur, but never mention its fundamental bearing problem. He later became editor of the AA. The AR turntable is one, but not the only issue I took.

The AR table came out in 1962. The original subchassis design was delrin cups that would swell after a period of time and sieze the spindle. Re-honing the well only addressed the issue for a short period. However, by 1964 AR had gone to a cast subchassis with babbit sleeve, and delrin thrust plate.
A babbit sleeve is a very quiet design. Moreso than phosphor bronze, or the crappy teflon sleeve(s) linn used early on that would fail due to additives found in most "normal" oils. The linn bearing(brochure) was in reference to the point of thrust. But, that is not where spindle bearing noise is. Once finished properly the spindle/ bearing well assembly on an XA, or XB is extremely quiet. Extremely low friction.
After all, the Ariston....errr.... Linn table is simply an AR XA with a butt load of money thrown at it.

 

[keilau]

The AR table came out in 1962. The original subchassis design was delrin cups that would swell after a period of time and sieze the spindle. Re-honing the well only addressed the issue for a short period. However, by 1964 AR had gone to a cast subchassis with babbit sleeve, and delrin thrust plate.
A babbit sleeve is a very quiet design. Moreso than phosphor bronze, or the crappy teflon sleeve(s) linn used early on that would fail due to additives found in most "normal" oils. The linn bearing(brochure) was in reference to the point of thrust. But, that is not where spindle bearing noise is. Once finished properly the spindle/ bearing well assembly on an XA, or XB is extremely quiet. Extremely low friction.
After all, the Ariston....errr.... Linn table is simply an AR XA with a butt load of money thrown at it.

Marc, thank you for the details. We may have hijacked this thread.

The spindle/bearing well assembly is exactly where the problem of the AR-XA turntable is. It should have very low friction, but no play in a good turntable. When you pull up the plater on a Linn or a Thorens turntable, you can feel the suction of the assembly. On the AR, you cannot feel the suction, and, in some case, you can feel the looseness of the spindle/bearing well assembly.

I agree that if the spindle/bearing well assembly is new (finished properly), the AR is a very quiet turntable. The problem was that it does not stay that way for long. On the other hand, the Linn's, the Thorens' will. You get what you pay for.

 

[marcmorin]

Marc, thank you for the details. We may have hijacked this thread.

The spindle/bearing well assembly is exactly where the problem of the AR-XA turntable is. It should have very low friction, but no play in a good turntable. When you pull up the plater on a Linn or a Thorens turntable, you can feel the suction of the assembly. On the AR, you cannot feel the suction, and, in some case, you can feel the looseness of the spindle/bearing well assembly.

I agree that if the spindle/bearing well assembly is new (finished properly), the AR is a very quiet turntable. The problem was that it does not stay that way for long. On the other hand, the Linn's, the Thorens' will. You get what you pay for.

Funny thing, my particular XA was built in 1964. I refinished the wells and the spindle, there is an additional 3.6 lbs of mass added to the subchassis. I can pick the whole table up by the sub platter. That's with a very light oil in the well, and a free spin time from 33.3 to zero of 5:15

 

[ken kantor]

Wow. It never ceases to amaze me how much of their lives "audiophiles" devote to finding obscure issues and inflating them into "big problems." Sure, I outgrew my AR table, but mainly because its arm was inconvenient and didn't work well with light weight and light tracking force cartridges.

-k

 

[keilau]

Wow. It never ceases to amaze me how much of their lives "audiophiles" devote to finding obscure issues and inflating them into "big problems." Sure, I outgrew my AR table, but mainly because its arm was inconvenient and didn't work well with light weight and light tracking force cartridges.

-k

Smile! It is for the fun of it.

It should be fairly easy to replace the AR arm.

I replace the stock Thorens arm with a Grace 707 when I wanted to use a Dynavector cartridge. Same table and arm combo for almost 30 years now.

 

[canuckaudiog]

Smile! It is for the fun of it.

It should be fairly easy to replace the AR arm.

I replace the stock Thorens arm with a Grace 707 when I wanted to use a Dynavector cartridge. Same table and arm combo for almost 30 years now.

As they say, to each their own..

Now, could we get back to the transmission line discussion that was so very interesting and intriguing?

 

[ken kantor]

Smile! It is for the fun of it.

It should be fairly easy to replace the AR arm.

I replace the stock Thorens arm with a Grace 707 when I wanted to use a Dynavector cartridge. Same table and arm combo for almost 30 years now.

For various reasons, I have never much enjoyed modifying other people's products. Sometimes a small adjustment here or there, but I would never change a factory arm on a turntable or change the tweeter in a speaker. However, I did build my own TT and arm in High School. Taught me a lot, but didn't work all that well. So I gave it to this girl....

[After my AR phase, I went with a Fons/SME combo that had its own issues. Eventually, the Fons was stolen in a break-in, and I went back to AR. Worked just fine, until I gave up my vinyl.]

Keilau, you are right, it >is< fun. However, being a factory-side guy, I do get a little tired of the constant assumption that professional audio engineers somehow don't know as much as the guys at the local audio club, or that all vestiges of quality and innovation are beat out of us by the Accounting Dept.

-k

 

[ken kantor]

As they say, to each their own..

Now, could we get back to the transmission line discussion that was so very interesting and intriguing?

I don't really have anything else to say about TL speakers. Sorry...

-k

 

[Dr Tinear]

Marc, thank you for the details. We may have hijacked this thread.

The spindle/bearing well assembly is exactly where the problem of the AR-XA turntable is. It should have very low friction, but no play in a good turntable. When you pull up the plater on a Linn or a Thorens turntable, you can feel the suction of the assembly. On the AR, you cannot feel the suction, and, in some case, you can feel the looseness of the spindle/bearing well assembly.

I agree that if the spindle/bearing well assembly is new (finished properly), the AR is a very quiet turntable. The problem was that it does not stay that way for long. On the other hand, the Linn's, the Thorens' will. You get what you pay for.

What's your definition of a long time? My 1974 XA-91 still exhibits high suction in both the spindle and arm bearings. There's no perceptible play at 40 years in service and the spindle bearing is quiet and low-friction. The 'table still sounds great, too.

 

[keilau]

Transmission Line Speaker stuffing

Ok, let's drop the TT topic and go back to speakers.

Other than Bailey and Bradbury, are there published data on different stuffing materials using the same cabinet and measurement method?

Result of Long fiber wool vs. fiber glass vs. polyfill vs. open cell foam?

With the physical characteristics of the stuffing materials properly documented. It may be difficult to make line terminus amplitude and phase measurement. But simple summed frequency response of the whole system and impedance curve would be very helpful.

A. R. Bailey published his "A Non-resonant Loudspeaker Enclosure Design" in October, 1965. It is 49 years. (No tuning is possible since the design is Non-resonant.) :nono:

 

[JimPA]

For some reason one of the links I had copied and paste doesn't work .

The article written by Gary A Galo [Transmission Line Theory] that appeared in 1-1982 Speaker Builder is on the internet.
If you do a Google search of Transmission Line Theory Cardoza and Company it will be found.
The file is too large to attach in a post.

 

[MJKing]

Other than Bailey and Bradbury, are there published data on different stuffing materials using the same cabinet and measurement method?

George Augspurger's JAES article from May 2000 is a good source of TL and fiber data :

http://diyaudioprojects.com/Technical/Papers/Loudspeakers-on-Damped-Pipes.pdf

His computer model and my computer model give the same results for the same geometric inputs and fiber stuffing even though they use different calculation methods. Both of us have measurements that correlate with the predictions, his are in the JAES article and a sampling of mine are included earlier in the thread. Neither of us agree with Bailey's and Bradbury's approach that the fibers move impacting acoustic performance.

 

[MJKing]

The article written by Gary A Galo [Transmission Line Theory] that appeared in 1-1982 Speaker Builder is on the internet.

The links don't work for me, maybe the file is corrupted. If I have time this weekend I will dig through my old Speaker Builder magazines and take a look at the article and offer my perspective.

 

[JimPA]

The links don't work for me, maybe the file is corrupted. If I have time this weekend I will dig through my old Speaker Builder magazines and take a look at the article and offer my perspective.

I can email the article to you if you send me an email with your email address so I can attach the file.
I have sent it to Canuckaudiodog in hopes that he can somehow post it on the forum and also to Ken

 

[keilau]

For some reason one of the links I had copied and paste doesn't work .

The article written by Gary A Galo [Transmission Line Theory] that appeared in 1-1982 Speaker Builder is on the internet.
If you do a Google search of Transmission Line Theory Cardoza and Company it will be found.
The file is too large to attach in a post.

Jim, I do not remember Gary Galo making any measurement of any kind in his 2 part articles. So I reached to my bookshelf and pulled out the 1/1982 and 2/1982 copy of the Speaker Builder. No, there was no measurement shown.

To Gary's credit, he basically sticked with the theory and conclusion of Bailey and Bradbury. He said that Dacron-polyester was a poor performer as transmission line stuffing material, but did not show any measurement. Knowing him, I would expect that he did try Dacron-polyester and did not like the sonic results.

 

[keilau]

Wrong stuffing for Transmission Line speaker

George Augspurger's JAES article from May 2000 is a good source of TL and fiber data :

http://diyaudioprojects.com/Technical/Papers/Loudspeakers-on-Damped-Pipes.pdf

His computer model and my computer model give the same results for the same geometric inputs and fiber stuffing even though they use different calculation methods. Both of us have measurements that correlate with the predictions, his are in the JAES article and a sampling of mine are included earlier in the thread. Neither of us agree with Bailey's and Bradbury's approach that the fibers move impacting acoustic performance.

Augspurger never bothered to try long fiber wool or open cell foam. He tested fiber glass, polyester fiber, microfiber and Acousta-Stuf. No one should be surprised that his resonant pipes do not work like the Bailey transmission line.

Augspurger did not bother to document the basic parameters of the fibers, such as density, diameter etc. of the fibers which are critical to the functioning of the transmission line design.

Augspurger tried to model his pipes as a linear resonant box. I guess that the frequency dependent, non-linear acoustic response of a long fiber wool filled transmission line to be too hard to accept by Augspurger.

 

[JimPA]

Jim, I do not remember Gary Galo making any measurement of any kind in his 2 part articles. So I reached to my bookshelf and pulled out the 1/1982 and 2/1982 copy of the Speaker Builder. No, there was no measurement shown.

To Gary's credit, he basically sticked with the theory and conclusion of Bailey and Bradbury. He said that Dacron-polyester was a poor performer as transmission line stuffing material, but did not show any measurement. Knowing him, I would expect that he did try Dacron-polyester and did not like the sonic results.

Gary showed the response graphs of the drivers used in his TL-5 enclosures in the 2-1986 issue.
The title of the article is Seven Transmission Line Midrange Drivers.

I am glad to hear that you have the back issues of Speaker Builder like myself.:yes:

 

[keilau]

Gary showed the response graphs of the drivers used in his TL-5 enclosures in the 2-1986 issue.
The title of the article is Seven Transmission Line Midrange Drivers.

I am glad to hear that you have the back issues of Speaker Builder like myself.:yes:

In the 2/1986 issue, the subject was midrange drivers. As a result, nothing below 100 Hz was reported.

Gary Galo did reported the measurement of 3 ten inches drivers in the TL-10 cabinet in issue 2/1985. It showed that the TL loading works very well in

1. Extending the low frequency response. All units had a -6 dB point around 20 Hz.
2. The very slow decay below 50 Hz showed that the TL loading worked as it should. The bass would be non-ringing and non-boomy.

Unfortunately, Gary did not show any companion impedance curve.

I also wish that he would have measured and showed the same TL-10 stuffed with polyester fiber to verify his claim that polyester was a poor performer for this purpose. :sigh:

So far, we have seen data from AR Bailey and Gary Galo that a "long fiber wool" filled transmission line will work as Bailey described. And from the data from George Augspurger and Martin King, a Dacron-polyester filled long pipe does not act like a transmission line.

Other than Bailey and Bradbury, are there published data on different stuffing materials using the same cabinet and measurement method?

Result of Long fiber wool vs. fiber glass vs. polyfill vs. open cell foam?

 

[JimPA]

Keilau the mailbox section of Speaker Builder had some of the most informative articles about T-line design.
The back and forth debates over so many subjects has taught me a lot.

 

[MJKing]

I can email the article to you if you send me an email with your email address so I can attach the file.
I have sent it to Canuckaudiodog in hopes that he can somehow post it on the forum and also to Ken

Jim,

I read the article you sent. I don't see a whole lot of engineering or understanding coming from the author. It looks like he has a few TL designs that work well that he formulated by trial and error. The rest of the article is just repeating the existing theories circulating at that time. He says a few good things but states just as many incorrect things, in my opinion and experience.

There are a lot of different articles and theories on TLs for people to read, many contradict each other. Until you have designed your own from scratch, built it, and then measured the results both acoustically and electrically with and with out fiber stuffing in my opinion you are talking without really knowing how firm the ground is beneath your feet. A TL speaker is just as predictable as a bass reflex or acoustic suspension speaker design.

I have provided my results, predictions and measurements, and explained the theory and my understanding of how a TL works. It has been dismissed without anything better being offered other than references to articles that people have read. I can continue to repeat what I have already said and provide more data as back up but I really don't see the point. If you have specific questions about what I have done or written I will be happy to answer then, but continuing to debate fantasy and magic is really of no interest to me.

Pick a TL religion and run with it, I wish you the best.

Martin