My Mass Rings Arrived!

[herki the cat]

Yes !!! How do we make our own Aquaplas ???

Verrry Interestink...ya ?

Make your own Aqualuas ???, I am pleased you asked, LE15-Thumper. Early 1970's I tried to buy some Aquaplas to no avail & the Aquaplas vendor or manufacturer had a 50 gallon barrel minimum. Michael Pearce in Cal, wanted $56.00 for a small pail of the stuff. I was able to buy a 5 gallon bucket at some $30.00 from the local "Sound Coat inc.," Acoustics Products vendor; none of which i have yet to use.

But i can tell you this. "The Aquaplas appears to be a mixture of "tung oil," & maybe a little varnish and some kind of a clay body. I think the worse that can happen to the tung oil is that it may oxidize in curring, which i think is required anyway to stabilize. I have used tung oil on my wood floors since 1950 and it is extremely flexible, durable and tough.

You may find it interesting to experiment with the ingredients mentioned. One question I have pondered Aka: I have seen, & so have other people, any number of Altec 500 series horns with a 1/2 inch coat of what i have been told is Aquaplas, which has cured hard as stone. In all fairness to jBL, I have seen no proof this coating on these horns is indeed Aquaplas, & if it is Aquaplas, it may well be that a very thin, cured coat is mechanically resistive to bending & does function perfectly well and stabile as excellent damping on a speaker cone or diaphragm.

Chears herki the cat

[Loren42]

I have seen, & so have other people, any number of Altec 500 series horns with a 1/2 inch coat of what i have been told is Aquaplas, which has cured hard as stone.

My understanding is that it is also available as a paste, so it may very well be what you describe.

[herki the cat]

A little review & a parting thought:

[quote=Loren42;281912]Mr. Widget you beat me to it.

[quote Mr. widget]
The 2234 and 2235 are not good candidates for sealed enclosures in my observation. The alignment with a Qtc of .707 is actually about 1 cubic foot. If you raise the volume the Qtc goes down very low.

MY thoughts would be that there are better drivers for a sealed enclosure than these and the Qes and Vas clearly indicate that the drivers are designed for vented enclosures. [quote/]

[Quote 4313B]
Greg ended up aquaplasing a pair of 2234H/2235H cones instead of using the mass rings. It worked out very well. Greg is a fan of just using the 2234H and then filling in the bottom end with Q. [quote/]

I have 2234s in my L200 3ways (see avatar image), but they originally came in my 4341 4ways. I got a pair of 2235s - tried them for a while in my L200s, but when I swapped the 2 pair so the 2235s were in the 4341s, and the 2234s were in the L200s, both sets sounded MUCH better. But it was a subtle difference.

Loren42, The 2234, and 2235 have a good reputation; Hjames obsevered only a very slight difference in the sound of the two drivers in her L300__ It seems that you can only use these drivers the way they were designed for a JBL speaker system. Monitor design is extremely complicated, employing cone speakers designs of sophysticated topology trade-offs adapted to yield excellent performance in reasonable size enclosures. There is no problem with the The matching superb JBL compression high frequency compression drivers & matching horns. Complexity of time alignment of the horns is accommodated by JBL digital delay active cross overs rather well.

It may be to your advantage to completly duplicate the widely acclaimed L200 Systems while parts are still available.

Herki

[Loren42]

[QUOTE=herki the cat;282086]A little review & a parting thought:

Mr. Widget you beat me to it.

[quote Mr. widget]
The 2234 and 2235 are not good candidates for sealed enclosures in my observation. The alignment with a Qtc of .707 is actually about 1 cubic foot. If you raise the volume the Qtc goes down very low.

MY thoughts would be that there are better drivers for a sealed enclosure than these and the Qes and Vas clearly indicate that the drivers are designed for vented enclosures. [quote/]

[Quote 4313B]
Greg ended up aquaplasing a pair of 2234H/2235H cones instead of using the mass rings. It worked out very well. Greg is a fan of just using the 2234H and then filling in the bottom end with Q. [quote/]



Loren42, The 2234, and 2235 have a good reputation; Hjames obsevered only a very slight difference in the sound of the two drivers in her L300__ It seems that you can only use these drivers the way they were designed for a JBL speaker system. Monitor design is extremely complicated, employing cone speakers designs of sophysticated topology trade-offs adapted to yield excellent performance in reasonable size enclosures. There is no problem with the The matching superb JBL compression high frequency compression drivers & matching horns have no problems. Complexity of time alignment of the horns is accommodated by JBL digital delay cross overs rather well.

It may be to your advantage to completly duplicate the widely acclaimed L200 Systems while parts are still available.

Herki

Yes, I was trying to show that a sealed design is not the way to go.

If you have been following my other threads about this speaker build you can see that it is coming together and I think that I will get a pretty good system out of it in the end. My biggest problem appears to be the room, but that is another topic.

My vented cabinet is a 3-way with almost 6.7 cubic feet. That will go down some when I add more internal bracing and cabinet wall treatments.

My F3 is currently at 33 Hz (according to BassBox Pro with the box tuned to 30 Hz) and I am left with dialing in the crossover networks and then working on improving the cabinet resonances. The JBL is currently crossed at 400Hz.

My intent was to bring my drivers up to JBL spec because that was what my cabinets were designed to.

The idea of utilizing 2234H drivers due to their improved mid bass is tantalizing. I am just not sure which way to go yet.

Here is an old link to my cabinet design:

Pyramids

The web page needs updating. I have replaced the mids with Audax PR170M0 drivers ( see here )and this crossover.

Once all that is done I have some very nice koa veneer waiting to be applied to the boxes.

[Ruediger]

1.) If You don't know if the cones are aftermarket or original, why don't You measure the Thiele Small parameters?

2.) Did You yet take Your amplifier's output impedance into account?

Ruediger

[herki the cat]

[quote=Loren42]
In my other threads, my speaker is coming together as a pretty good system. My problem appears to be the room,= another topic. Utilizing 2234H drivers with improved mid bass is tantalizing. Here is an old link to my cabinet design; I have some very nice koa veneer to apply to the boxes. [/quote]

click: Pyramids to view image of Loren42's Pyramids Speakers...

Loren42, your "Pyramids" Enclosure's are absolutely gorgeous, & do represent a tremendous professional work of art. I had no idea since i chimed in on the last page of the 2234/2235 issue.

You may wish to refine the (speaker vs room) artifacts issue, and investigate the speakers isolated from the room, perhaps out of doors. I have found that even when the speaker system has a very smooth, flat, measured frequency response, that Ringing or Hangover modes may persist after the drive signal ends due to speaker system hang-over ringing undamped artifacts, which represent "duration of sound energy" equivalent to the perceived increased loudness properties of room reverberation.

The explanation is that "perceived, increased loudness" occurs acoustically in two ways. (1)...Increasieing the signal amplitude, or (2)...Adding duration to the signal, which is equivalent to natural room or auditorium reverberation sound, because that sound continues to stimulate the hearing function of the ear after the original direct sound has ceased; This loudness characteristic of reverberation becomes more intense, inversely proportional to frequency, particularly noticeable at the lower frequencies in the mid bass spectrum due to decreasing attenuation of sound energy propogating in air. This is how a nice big auditorium enhances the sound of an orchestra, which would otherwise sound like a" mashed potato sandwich" with the orchestra performing out of doors in a cow pasture.

This test is very easy to perform by using a "tone burst" generator and oscilloscope to view the the speaker output with a microphone. A tone sweep from 20 Hz to 20,000 Hz in slow incremental steps is interrupted after eight cycles of stepped frequency for viewing any hang over in speaker output during g eight cycles of zero signal application to the driving amplifier. Any hang over ringing lasting more than 1/2 cycle is considered to be "not acceptable."

I will be comunicatingwith you via Email.

Herki

[Loren42]

[QUOTE=herki the cat;282123]

In my other threads, my speaker is coming together as a pretty good system. My problem appears to be the room__ another topic. Utilizing 2234H drivers with improved mid bass is tantalizing. Here is an old link to my cabinet design; I have some very nice koa veneer to apply to the boxes. [/quote]

click: Pyramids to view image of Loren42's Pyramids Speakers...

Loren42, your "Pyramids" Enclosure's are absolutely gorgeous, & do represent a tremendous professional work of art. I had no idea since i chimed in on the last page of the 2234/2235 issue.

You may wish to refine the (speaker vs room) artifacts issue, and investigate the speakers isolated from the room, perhaps out of doors. I have found that even when the speaker system has a very smooth, flat, measured frequency response, that Ringing or Hangover modes may persist after the drive signal ends due to speaker system hang-over ringing undamped artifacts, which represent "duration of sound energy" equivalent to the perceived increased loudness properties of room reverberation.

The explanation is that "perceived loudness" occurs acoustically in two ways. (1)...Increasieing the signal amplitude, or (2)...Adding duration to the signal, which is equivalent to the natural room or auditorium reverberation sound, because that sound continues to stimulate the hearing function of the ear after the original direct sound has ceased. This is how a nice big auditorium enhances the sound of an orchestra, which would otherwise sound like eating a "mashed potato sandwich" with the orchestra performing out of doors in a cow pasture.

This test is very easy to perform by using a "tone burst" generator and oscilloscope to view the the speaker output with a microphone. A tone sweep from 20 Hz to 20,000 Hz in slow incremental steps is interrupted after eight cycles of stepped frequency for viewing any hang over in speaker output during g eight cycles of zero signal application to the driving amplifier. Any hang over ringing lasting more than 1/2 cycle is considered to be "not acceptable. "

I will be comunicatingwith you via Email.

Herki

The term 'hang over' is new to me. I probably know it by anther term, but if you could define it for me I would be grateful.

I believe I have some rather incredulous room issues. Look at this far field plot at my current listening position:



I plan to run a plot with one of the speakers outside, but Florida is not cooperating right now. The temperature is nice, but we get a lot of wind and I need a calm day to do this right.

Florida has another issue and that is most homes make spacious use of ceramic tile. We have lots of tile in our house and surprisingly, it makes a very good acoustic mirror.

While you can do gated measurements, the floor makes this problematic. I have tried carpet pieces laid down before the speaker and have had little help.

This is one of the issues with the room, which is currently set up like this:



The living area shares space with the kitchen, so I have a pretty live room with lots of nodes and antinodes (as proven by my room sweep). We have a room renovation on the radar screen some day in the future and that will be the best time to figure out room treatments. Meanwhile I want to get the speakers dialed in.

Near field and ground plane measurements do hint at a reasonably flat response so far. I expect when the cabinets are dragged outside that those measurements will confirm a good response. I also need to take off-axis responses so that I can tweak the crossover design.

Lastly, if hang over is related to cabinet resonances, then that is another issue to work on with these cabinets. I bought an accelerometer and will be doing a baseline on the current cabinets and then work on inner wall treatments to reduce wall ringing. I may first build a test box with a removable panel that I can try different techniques, including constrained layering, to minimize wall resonances.

So, as I said before, my original design path was with the 2235H. Realizing that a 2234H may offer better mid bass is a consideration that I need to work out... Door number one... or door number two???

[Loren42]

1.) If You don't know if the cones are aftermarket or original, why don't You measure the Thiele Small parameters?

2.) Did You yet take Your amplifier's output impedance into account?

Ruediger

1. I did the Fs, but I did not do the rest of the measurements (as described in Vance Dickason's book). When I saw 23 Hz as the measured Fs I sort of got suspicious and ordered rings just in case. They are cheap at $3 each, my domes are crinkled up and need replacement, so I thought, "why not?"

2. I figured the amp's impedance at 1 Ω.

[Ruediger]

1. I did the Fs, but I did not do the rest of the measurements (as described in Vance Dickason's book). When I saw 23 Hz as the measured Fs I sort of got suspicious and ordered rings just in case. They are cheap at $3 each, my domes are crinkled up and need replacement, so I thought, "why not?"

2. I figured the amp's impedance at 1 Ω.

I don't know what kind of equipment You use and what Your measurement error is. But there will be some error. Also the 20 Hz resonant frequency are an average value with some error. The 23 Hz might be the result of a slightly-out-of-spec 2235 and some measurement error.

You should measure the whole set of TS parameters so that You know what kind of animal You have.

1 Ohm amplifier output impedance is a lot. The series coil in the crossover will add some more resistance. You need to calculate the resulting total Q. For this Qt You can then design a box.

Ruediger

[Loren42]

I don't know what kind of equipment You use and what Your measurement error is. But there will be some error. Also the 20 Hz resonant frequency are an average value with some error. The 23 Hz might be the result of a slightly-out-of-spec 2235 and some measurement error.

You should measure the whole set of TS parameters so that You know what kind of animal You have.

1 Ohm amplifier output impedance is a lot. The series coil in the crossover will add some more resistance. You need to calculate the resulting total Q. For this Qt You can then design a box.

Ruediger

I can see that.

One thing I do need to do is replace the paper domes. Once I take that off I will know if it is a 2235H or 2234H by observation.

The sticking point now is not so much whether it does or does not have the mass ring, but if it doesn't have a mass ring, should I install one?

There have been some compelling arguments that a 2234H would be a better driver (assuming that I EQ the mid bass down about 3 dB). I just have not made up my mind yet. That's the conundrum.

[Ruediger]

I can see that.

One thing I do need to do is replace the paper domes. Once I take that off I will know if it is a 2235H or 2234H by observation.

The sticking point now is not so much whether it does or does not have the mass ring, but if it doesn't have a mass ring, should I install one?

There have been some compelling arguments that a 2234H would be a better driver (assuming that I EQ the mid bass down about 3 dB). I just have not made up my mind yet. That's the conundrum.

So the question is "which is better? 2234 or 2235". Simply look up the TS params for the two speakers and check which of them allows for the Thiele alignment which suits You best.

Given the high output impedance of Your amplifier You 1st need to take that into consideration, as well as the DC resistance of the series coil in Your crossover (make an educated guess**). You need to calculate the resulting Qt.

I would not at all care about group delay, slew rate, aquaplasing etc. JBL has designed the two woofers, with excellent results. Both drivers are good up to 1 kHz. What else do You want?

I do have only very bad copies of Thiele's tables. If I would scan them again nobody could read them. DOES ANYBODY HERE IN THE FORUM HAVE GOOD COPIES OF THIELE'S PAPERS?

Let's stay tuned. Ruediger

[Ruediger]

Take the crossover for the 4430, check the inductivity (mH) of the series coil. Look up the prices for different forms of coils with that inductivity (forget the coreless ones), see how much You need to pay for a small DC resistance.

Ruediger

[Ruediger]

I found copies in reasonable quality on the net and published them in the General Audio Discussion group.

Enjoy!
Ruediger

[Loren42]

So the question is "which is better? 2234 or 2235". Simply look up the TS params for the two speakers and check which of them allows for the Thiele alignment which suits You best.

Given the high output impedance of Your amplifier You 1st need to take that into consideration, as well as the DC resistance of the series coil in Your crossover (make an educated guess**). You need to calculate the resulting Qt.

I would not at all care about group delay, slew rate, aquaplasing etc. JBL has designed the two woofers, with excellent results. Both drivers are good up to 1 kHz. What else do You want?

I do have only very bad copies of Thiele's tables. If I would scan them again nobody could read them. DOES ANYBODY HERE IN THE FORUM HAVE GOOD COPIES OF THIELE'S PAPERS?

Let's stay tuned. Ruediger

Actually, what would be more valuable would be the "acoustic data" for the 2235 and 2234 so I could import it into Bass Box Pro and Xover Pro. Even better would be the acoustic data for my woofer!

I have the T/S parameters already in the BassBox Pro library, but there is no acoustic data for those drivers nor my Audax midrange.

I don't understand the procedure to generate my own acoustic data from my drivers nor what tools I would need to do it. Anyone have clues?

I believe this data is then input into the "Response" tab of the library driver data. Having this data will allow me to more accurately model my crossover and box.

[Loren42]

I pulled one of my JBL 2235Hs from the cabinet and checked the inscribing on the back of the cone.

I feel comfortable that they were, in fact, reconed as 2235Hs after all using JBL parts.

The cone back has the JBL cartouche on the cone that reads:

JBL
PRO
21

with a white circle around it. Hand scribed on the other side is 2235H. There are some unintelligible signature and the presumed serial number:

50320

I would assume that the mass rings were installed if the cone is hand marked 2235H, but I need to replace the domes and when I do I will confirm if the rings are present. If they are I do not intend to try to remove them.

I can also assume the recone used genuine JBL parts, which makes me happy, too.