Philips 10100-8 10" woofer replacement in Transmission Line cabinets

[keilau]

A long time ago, I built 2 TL speakers using the Philips 10100-8 10" woofer in the original Bailey line (Wireless World 1965). It was used with a pair of Janzsen electrostatic tweeters. Wonderful sound but somewhat restrained due to the power handling of the Janzsens. I moved to other speakers and the TL went into storage.

The cabinet is filled with long fiber wools to make it into a half wavelength phase inverter and a non-resonant tube. It gave very tight bass extended down to 30 Hz as Bailey intended. Bailey used the KEF B139 woofer which was too expensive. This design worked very well with the Philips and the Bailey theory was proved by his experiment. Modern designs that claims to be transmission line typically use unfilled quarter wavelength air column. The low frequency sound is loose and not very extended.

I got the TL out of storage recently and found the rubber surrounds have losen its compliance. I intended to use the pair as subwoofer under 120 Hz. I am looking for a drop-in replacement of the Philips 10100-8. Peerless used to make some units at very reasonable price (850146, 831727, 830634) which were no longer available. Among the current Parts Express stock, I am looking at Peerless 830668 and Dayton Audio DC250-8. Any first hand experience using them in a true long fiber wool filled transmission line? or suggestion for alternative at affordable price (<$75 per piece).

Any comment about the pros and cons of trying to re-rubber the Philips 10100?

[billfitzmaurice]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

You should be able to find T/S specs for the B139 and find another ten that comes close.

[keilau]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

You should be able to find T/S specs for the B139 and find another ten that comes close.

The Thiele-Small parameters are important only in bass reflex box design. Matching the B139 T/S parameters will be very expensive and not necessary for transmission line design which is inherently a non-resonant approach. The Dayton Audio DC250-8 is inexpensive and has most the parameters right. However, the Xmax is a smallish 4.5 mm. Will it sound compressed in a loud passage? Yes, I can go with the Peerless 830668 at twice the price. But the resonant frequency is a high 32 Hz.

I noticed that in recently years, a lot of speaker builders were misled into building resonant 1/4 wavelength air colume instead of the long fiber wool filled transmission line. I just wonder if there is any real TL speaker builder left.

[Chris Roemer]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

T/S parms are used for all box designs, even closed and PR, and even for mid subenclosures. YOUR design may not have used them back whenever, but that doesn't mean that measuring and nearly duplicating those of the driver you originally used won't get you very close to a near match in performance. And Fs IS a T/S parm.

[Pete Schumacher]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

keilau, don't come asking for advice and then discount what the knowledgeable people here offer in response to your question.

TL design has come a long way since that line you have was first created through trial and error. TS parameters are every bit as important to design a predictable line as they are for vented box applications. If you don't utilize those parameters that define the low frequency behavior of a woofer, then anything you put in there is a total crap shoot.

Let's start by having you give us the dimensions of this line. How many cubic feet are contained within the line? Where is the woofer in relation to the closed end of the line and how long is the line. How large an area defines the closed end of the line and what is the area of the open terminus? Knowing the size and makeup of the line will allow those of us who know how to design TLs help you pick a woofer with suitable performance to work well with the line you have, maybe without modification to the line.

And if you still think you want to figure this out on your own, here's a great site that will cover the various types of open box designs of which TLs make one small subset.

http://www.quarter-wave.com/

[keilau]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

T/S parms are used for all box designs, even closed and PR, and even for mid subenclosures. YOUR design may not have used them back whenever, but that doesn't mean that measuring and nearly duplicating those of the driver you originally used won't get you very close to a near match in performance. And Fs IS a T/S parm.

Chris,

Thiele/Small parameters are named after A. Neville Thiele of the Australian Broadcasting Commission, and Richard H. Small of the University of Sydney. They published a series of papers in the Journal of Audio Engineering Society in the early 1970's. Those papers were specifically for vented and closed box design derived from filter theory. I have a collection of these and related papers. Did you read them carefully yet?

It is true that the transmission line speaker developed by Dr A.R. Bailey and A.H. Radford was published in 1965. It was based on the theory of a terminated transmission line with no reflection from the end. They did a very careful study based on calculus and laboratary measurements. There was no easy closed form mathematical equations like the T/S papers. Mostly becasue the effect of the long fiber wool on sound wave is highly non-linear. Its calculation requires more than simple algebra that most people can handle. As a result, there are many recent misleading publications using quarter wave empty air column resonance equation and claiming to be transmission line. They do not work because they do not account for the effect of the long fiber wool. The Bailey/Radford paper is fascinating reading if you can follow the nonlinear calculation on how the slowing down and phase change of the acoustic wave in the TL cabinet is dependent on the frequency. BTW, the calculation was difficult in 1965. But it can be easily programmed into PC this days. What is your impression of the Bailey/Radford paper?

If you have a chance to listen to a long fiber wool filled transmission line speaker design, you will be amazed by how balanced but yet well damped the base is. There is just no comparison in quality that it is so much better than vented or closed box design using similar woofer.

[Pete Schumacher]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

Chris,

Thiele/Small parameters are named after A. Neville Thiele of the Australian Broadcasting Commission, and Richard H. Small of the University of Sydney. They published a series of papers in the Journal of Audio Engineering Society in the early 1970's. Those papers were specifically for vented and closed box design derived from filter theory. I have a collection of these and related papers. Did you read them carefully yet?

It is true that the transmission line speaker developed by Dr A.R. Bailey and A.H. Radford was published in 1965. It was based on the theory of a terminated transmission line with no reflection from the end. They did a very careful study based on calculus and laboratary measurements. There was no easy closed form mathematical equations like the T/S papers. Mostly becasue the effect of the long fiber wool on sound wave is highly non-linear. Its calculation requires more than simple algebra that most people can handle. As a result, there are many recent misleading publications using quarter wave empty air column resonance equation and claiming to be transmission line. They do not work because they do not account for the effect of the long fiber wool. The Bailey/Radford paper is fascinating reading if you can follow the nonlinear calculation on how the slowing down and phase change of the acoustic wave in the TL cabinet is dependent on the frequency. BTW, the calculation was difficult in 1965. But it can be easily programmed into PC this days. What is your impression of the Bailey/Radford paper?

If you have a chance to listen to a long fiber wool filled transmission line speaker design, you will be amazed by how balanced but yet well damped the base is. There is just no comparison in quality that it is so much better than vented or closed box design using similar woofer.

How about something a little more current, that accounts for fiber damping, and which also includes TS parameters?

http://www.quarter-wave.com/TLs/TL_Theory.html

This approach uses computer modeling and is based on experimental verification.

http://www.quarter-wave.com/TLs/Damping_Coefficient.pdf

[keilau]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

keilau, don't come asking for advice and then discount what the knowledgeable people here offer in response to your question.

TL design has come a long way since that line you have was first created through trial and error. TS parameters are every bit as important to design a predictable line as they are for vented box applications. If you don't utilize those parameters that define the low frequency behavior of a woofer, then anything you put in there is a total crap shoot.

Let's start by having you give us the dimensions of this line. How many cubic feet are contained within the line? Where is the woofer in relation to the closed end of the line and how long is the line. How large an area defines the closed end of the line and what is the area of the open terminus? Knowing the size and makeup of the line will allow those of us who know how to design TLs help you pick a woofer with suitable performance to work well with the line you have, maybe without modification to the line.

And if you still think you want to figure this out on your own, here's a great site that will cover the various types of open box designs of which TLs make one small subset.

http://www.quarter-wave.com/

Pete Schumacher,

I did not do any re-design of the Bailey/Radford line. The construction was well documented in the 1965 and 1972 papers in the Wireless World. I did not change anything from the papers. I hope that you are familiar with those papers too.

The Philips woofer was selected based on J. Theodore Jastak's article in the 1973, Issue #1 of The Audio Amateur. It cannot be emphasized enough the importance of using the long fiber wool to fill the TL. I was in Minnesota in the 70's and was able to find a wool mill that provide wool batter to Janzsen Speakers (in Minneapolis then). They had the exact specification of wool fiber that Bailey specified. Most synthetic fiber have the wrong diameter and weight and do not work in transmission line speakers. You have to listen to tell the difference. You can do phase measurement like Baily did too to verify the theory.

You need to read the original Bailey/Radford paper to understand how the TL speaker works. The quarter-wave.com site you quoted is very misleading. See my reply to Chris Roemer for more details of my points. Martin J. King tried to change the Bailey theory. But he did not understand how the long fiber wool works in the original design. The "quarter wave" name is a dead give away. You have to have a half wavelength to get an effective phase inverter. Your comments convinced me that you have not read the Bailey/Radford papers either.

I have no intension to deviate from the original Bailey design and am not seeking advise on how to re-design TL speaker. I am asking which woofer available TODAY best meet the requirement of the original long fiber wool filled TL in Bailey's design. I am sorry if I did not make it clear at the beginning.

[Pete Schumacher]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

Pete Schumacher,

I did not do any re-design of the Bailey/Radford line. The construction was well documented in the 1965 and 1972 papers in the Wireless World. I did not change anything from the papers. I hope that you are familiar with those papers too.

The Philips woofer was selected based on J. Theodore Jastak's article in the 1973, Issue #1 of The Audio Amateur. It cannot be emphasized enough the importance of using the long fiber wool to fill the TL. I was in Minnesota in the 70's and was able to find a wool mill that provide wool batter to Janzsen Speakers (in Minneapolis then). They had the exact specification of wool fiber that Bailey specified. Most synthetic fiber have the wrong diameter and weight and do not work in transmission line speakers. You have to listen to tell the difference. You can do phase measurement like Baily did too to verify the theory.

You need to read the original Bailey/Radford paper to understand how the TL speaker works. The quarter-wave.com site you quoted is very misleading. See my reply to Chris Roemer for more details of my points. Martin J. King tried to change the Bailey theory. But he did not understand how the long fiber wool works in the original design. The "quarter wave" name is a dead give away. You have to have a half wavelength to get an effective phase inverter. Your comments convinced me that you have not read the Bailey/Radford papers either.

I have no intension to deviate from the original Bailey design and am not seeking advise on how to re-design TL speaker. I am asking which woofer available TODAY best meet the requirement of the original long fiber wool filled TL in Bailey's design. I am sorry if I did not make it clear at the beginning.

I'm not asking you to change a thing about your line. Just reveal the specifics of the line dimensions, driver placement in the line, and from that a suitable driver can be determined.

Martin's work includes long fiber wool, along with experimental work to verify his calculations which most assuredly are the equal, if not the better of the original article you cite. Or did you even bother to read through the theory and calculations?

TLs are quarter wave devices, and always have been. The "phase inversion" you mentioned above is exactly the result of a line that is a quarter wave, inverting the rear wave of a cone driver, returning it to an in-phase wave with that from the front of the cone.

Before you go on disparaging Martin's work, spend some time with it and get back to us. You might just find yourself getting an education.

[keilau]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

I'm not asking you to change a thing about your line. Just reveal the specifics of the line dimensions, driver placement in the line, and from that a suitable driver can be determined.

Martin's work includes long fiber wool, along with experimental work to verify his calculations which most assuredly are the equal, if not the better of the original article you cite. Or did you even bother to read through the theory and calculations?

TLs are quarter wave devices, and always have been. The "phase inversion" you mentioned above is exactly the result of a line that is a quarter wave, inverting the rear wave of a cone driver, returning it to an in-phase wave with that from the front of the cone.

Before you go on disparaging Martin's work, spend some time with it and get back to us. You might just find yourself getting an education.

Pete,

Why don't you read the Bailey/Radford articles and the Martin King web articles and make your own comparison. I did. I am an engineer in trade and made my own judgement based on the physics in both.

My cabinet dimension and driver selection were well documented in the ariticles I cited. They are classics in the field of transmission line speakers. I don't see the need to restate the obvious.

Martin King claimed that he measured "long fiber wool" without disclosing what he used, and the dimensions of his "long fiber wool". But when he said that "wool might provide a little less viscous damping for the same packing density" and "there is no magic associated with a wool stuffed transmission line", it directly contradicted the more scientifically accurate theory and measurement of Dr. Bailey did in 1965. Martin King's damping factor calculation assumed adiabatic mixing of very fine Dracon fibers in air by combining their density. Good for box enclosure analysis as detailed by Richard Small, but not applicable to transmission line with long fiber wool.

By the way, the backside acoustic wave is 180 degrees out of phase with the front side. Therefore, a phase inverter is half wavelength. A quarter wave is 90 degree out of phase and the result applies to a acoutistically shorter Dracon filled line. It will not sound right. Martin King's analysis was based mostly on Richard Small's vented box article. He did not make any reference to the Bailey Transmission line articles or the early Audio Amateur article at all. I wonder why?

[Paul K.]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

First of all, there is nothing magical about long fiber wool, although its absolute effects will be somewhat different from other materials. The reason it was used "back then" is primarily because it was about the only practical thing available. Second, in a column with one end closed and the other open, its primary resonance will be the 1/4-wavelength. You have no choice in this, it's simply physics/acoustics. You can use stuffing (whatever the material) to alter/shape the low-end response, and if you use enough (by density but most assuredly by length) you can make the column act in a non-resonant mode because you have literally stuffed the life out of it. By doing that, you have completely eliminated all contribution to the system from the terminus. You might as well just build a really big sealed box and be done with (BTW a sealed column will have its primary resonance at 1/2-wavelength). And, like Pete said, if you don't optimize the line's configuration for the driver's T/S values, it will for sure be a C R A P shoot. In case you didn't know, both Pete and I are also engineers; I have a BSEE and I think Pete does, too.
Paul

Pete,

Why don't you read the Bailey/Radford articles and the Martin King web articles and make your own comparison. I did. I am an engineer in trade and made my own judgement based on the physics in both.

My cabinet dimension and driver selection were well documented in the ariticles I cited. They are classics in the field of transmission line speakers. I don't see the need to restate the obvious.

Martin King claimed that he measured "long fiber wool" without disclosing what he used, and the dimensions of his "long fiber wool". But when he said that "wool might provide a little less viscous damping for the same packing density" and "there is no magic associated with a wool stuffed transmission line", it directly contradicted the more scientifically accurate theory and measurement of Dr. Bailey did in 1965. Martin King's damping factor calculation assumed adiabatic mixing of very fine Dracon fibers in air by combining their density. Good for box enclosure analysis as detailed by Richard Small, but not applicable to transmission line with long fiber wool.

By the way, the backside acoustic wave is 180 degrees out of phase with the front side. Therefore, a phase inverter is half wavelength. A quarter wave is 90 degree out of phase and the result applies to a acoutistically shorter Dracon filled line. It will not sound right. Martin King's analysis was based mostly on Richard Small's vented box article. He did not make any reference to the Bailey Transmission line articles or the early Audio Amateur article at all. I wonder why?

[fdieck]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

I actually built the Bailey TL in 1976 with the KEF B139 and long fiber wool. It sounded pretty good but not as good new TL designs. It had a lot of subsonic cone motion (turntable days) and lacked the weight and impact of newer TL designs. I can't image this should be surprising since it was designed over 40 years ago...... I seem to recall some article questioning some Bailey's analysis. I don't even know of anyone selling wool for TLs anymore but you could by in the late 70s. I love TLs but thinking the pinnacle of the art was over 40 years ago is nostalgia run amuck. I also have a BSEE but claim no skills in thermodynamics.

[billfitzmaurice]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

Pete,

Why don't you read the Bailey/Radford articles and the Martin King web articles and make your own comparison.

Better yet, you read the AES articles by George L. Augspurger. His work was to TLs as Theile/Small were to vented boxes. It addresses all of your concerns, showing where Voigt, Bradbury and Bailey were correct, and where they were off the mark. Perhaps those three would have been closer to being correct had they the ability to incorporate T/S into their calculations, but as they pre-dated T/S they obviously could not do so.
If you are not an AES member and don't wish to purchase the Augspurger preprints this thesis is the next best thing, which expands even further beyond Augspurger's initial work:

http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf

[Pete Schumacher]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

Pete,

Why don't you read the Bailey/Radford articles and the Martin King web articles and make your own comparison. I did. I am an engineer in trade and made my own judgement based on the physics in both.

My cabinet dimension and driver selection were well documented in the ariticles I cited. They are classics in the field of transmission line speakers. I don't see the need to restate the obvious.

Martin King claimed that he measured "long fiber wool" without disclosing what he used, and the dimensions of his "long fiber wool". But when he said that "wool might provide a little less viscous damping for the same packing density" and "there is no magic associated with a wool stuffed transmission line", it directly contradicted the more scientifically accurate theory and measurement of Dr. Bailey did in 1965. Martin King's damping factor calculation assumed adiabatic mixing of very fine Dracon fibers in air by combining their density. Good for box enclosure analysis as detailed by Richard Small, but not applicable to transmission line with long fiber wool.

By the way, the backside acoustic wave is 180 degrees out of phase with the front side. Therefore, a phase inverter is half wavelength. A quarter wave is 90 degree out of phase and the result applies to a acoutistically shorter Dracon filled line. It will not sound right. Martin King's analysis was based mostly on Richard Small's vented box article. He did not make any reference to the Bailey Transmission line articles or the early Audio Amateur article at all. I wonder why?

What's becoming obvious to me, and apparently others, is that experimentally verified theory on the approach to building a predictable T-line doesn't sit well with you. You're stuck in a paradigm that was arrived at by pure trial and error with an explanation that does not include woofer parameters. If parameters don't matter, then just throw a woofer in there and you're good to go.

[fdieck]

Re: Philips 10100-8 10&quot; woofer replacement in Transmission Line cabinets

What's becoming obvious to me, and apparently others, is that experimentally verified theory on the approach to building a predictable T-line doesn't sit well with you. You're stuck in a paradigm that was arrived at by pure trial and error with an explanation that does not include woofer parameters. If parameters don't matter, then just throw a woofer in there and you're good to go.

I think you just cut that Gordian knot with the sword of reason.