Beyond the Ariel

[Lynn Olson]

Sorry to interrupt the research ....

Just thought Gary and Lynn might like the attached pic of my first Jensen bass unit for the combination . I know it took me a barely finite amount of time to do this, but I'm quite proud of the woodwork !

I got some autoformers for the 288-H's from Dave a while back, and it was nice to find the horns sounded the same with or without the autoformers .

Good effort Dave!

Mark

Wow! Now that's classy! Very impressed with the quality and beauty of the cabinetry. Gary and Mark are doing impressive work. Still meditating on the resistive-vent alignment suggested by Planet10 for an Altec 416/TD15M type of driver - a scaled-up version of the Fonken. Out of curiosity, Mark, what are the cabinet dimensions?

FWIW, Paul W. built a pretty good MTM speaker that had rave reviews during a DIY event in Atlanta.

It uses the 18sound wavguide (XT1464)/1.4 CD (ND1460A). I think its breakup was up past 14KHz.

The measurements are here.

HTGuide Forum - View Single Post - The Raptor ... a 10" MTM

Conveniently enough, I already have a pair of 18Sound XT1464 horns on hand, and the throat flare of the aluminum-diaphragm ND1460A is compatible with the AH425 horn, so a comparison between the three large-format compression drivers (288, 745PB, ND1460A) is quite possible.

 

[g3dahl]

45 deg tangent point before the lip is how far from the horn throat on axis?

Not sure what you mean, sorry!

Gary Dahl

 

[soongsc]

Not sure what you mean, sorry!

Gary Dahl

When the horn flares, there is a point where the tangent line is 45 deg to the center axis. How far is that point from the horn throat entry point as measured along the center axis?

 

[doug20]

Those measurements look great. I remember looking at that driver, but the manufacturer's curve didn't look nearly so good. Is that an unequalized measurement?

If so, and if it is compatible with the AH-425, it would definitely be worth a try!

Gary Dahl

That is a good question. I can not answer it.

 

[g3dahl]

Just read the thread on htguide. Below is just the horn and driver at 2 m, at 0, 10, 20, 30 and 40 degrees off axis. Paul said that the deep notch at 14 kHz didn't happen with his other ND1460A's on his own waveguides.

And here is the woofer response:

It's an interesting thread. Paul did impressive work to integrate the system so nicely. Wish I could take a listen.

Here's the thread: HTGuide Forum - The Raptor ... a 10" MTM

Gary Dahl

 

[mige0]

When the horn flares, there is a point where the tangent line is 45 deg to the center axis. How far is that point from the horn throat entry point as measured along the center axis?

Whats the reason behind ???

 

[soongsc]

Whats the reason behind ???

That's my personal preference for definition of horn termination point.

 

[soongsc]

Just read the thread on htguide. Below is just the horn and driver at 2 m, at 0, 10, 20, 30 and 40 degrees off axis. Paul said that the deep notch at 14 kHz didn't happen with his other ND1460A's on his own waveguides.

And here is the woofer response:

It's an interesting thread. Paul did impressive work to integrate the system so nicely. Wish I could take a listen.

Here's the thread: HTGuide Forum - The Raptor ... a 10" MTM

Gary Dahl

Diffraction is quite obvious. It would be interesting to see a CSD.

 

[sendler]

16"

The wavelet ripples at 0.6 ms intervals correspond to distances of about 8 inches. The depth of the AH-425 on axis, without the driver, is 10 inches. The inside wall of the horn measures about 16" from the bugscreen to the edge of the mouth, so I'm not sure of the exact mechanism that is causing the 0.6 ms ripples.

It must be a harmonic of the 16" path length to the edge.

 

[soongsc]

I thought "harmonic" was a frequency domain thing.

 

[sendler]

Waves

I thought "harmonic" was a frequency domain thing.

Harmonic is a wave thing.
Physics Tutorial: Guitar String Harmonics

 

[soongsc]

So, it should show up in frequency domain which does not seem to be the case.

 

[Paul W]

Diffraction is quite obvious. It would be interesting to see a CSD.

What we both thought was diffraction turned out to be reflection from a projector box hanging from the ceiling...I moved the mic into a position to "see" the reflection...oops! Pretty sure there is a CSD plot in the thread.

 

[sendler]

WTF sensitivity

So, it should show up in frequency domain which does not seem to be the case.

So I guess this is another example of the very sensitive wavelet transform showing us something that is so minor that we won't hear it.

 

[soongsc]

What we both thought was diffraction turned out to be reflection from a projector box hanging from the ceiling...I moved the mic into a position to "see" the reflection...oops! Pretty sure there is a CSD plot in the thread.

Referring to the plots below, if it were a projector box, I would have expected all curve to show the same wriggles. If you were moving the mic to do off-axis measurements, then it would be a different story. I just assumed one would rotate the speaker.

Just read the thread on htguide. Below is just the horn and driver at 2 m, at 0, 10, 20, 30 and 40 degrees off axis. Paul said that the deep notch at 14 kHz didn't happen with his other ND1460A's on his own waveguides.

And here is the woofer response:

It's an interesting thread. Paul did impressive work to integrate the system so nicely. Wish I could take a listen.

Here's the thread: HTGuide Forum - The Raptor ... a 10" MTM

Gary Dahl

Hmm, looked through that thread. The CSD of the horn looked nice, wonder what happened when it got integrated with the system.

 

[IslandPink]

Jensen

Lynn
You asked a few days ago about the Onken/Jensen cabinets I'm making .
The design is basically the standard design as given on the Supravox site :
http://www.supravox.fr/kits/jensen.pdf

I looked for a while at alternative alignments but could see the inevitable trade-offs of low-end extension . I'm not intending to add any further bass complexity due to space considerations . I'm hoping it will be an OK trade-off with the nice Supravox 285GMF which have very light cones .
The current philosophy will be to drive these bass speakers from a Pass F4 driven from a valve linestage or a pick-off from the driver of the SE amp that will be driving the Horns and G3 ribbons . I'm hoping the Class-A and feedbackless nature of the F4 will help integration between bass and mid sections . I should at least get the same sort of spatiality from the F4 as a valve SE amp .

Mark

 

[mige0]

Michael !

Would't it be a good idéa to make a document (which you seem to like to do) with your CMP theories and put that at your place "Audio and Loudspeaker Design Guidelines".
Per

Excellent idea ! - where did I have my thoughts ?


...
Michael

For what it is worth - enjoy !


http://www.kinotechnik.edis.at/page...ine/CMP_Behaviour–Bridging_Points_of_View.pdf


Michael

 

[mige0]

No longer hijacking this thread with "shuddering" topics...

http://www.diyaudio.com/forums/everything-else/173283-cmp-framing-what-you-mean.html#post2297865

 

[slowmotion]

Any more news on Gary's progress?

 

[g3dahl]

I can give a quick update...

The low pass filter for the TD15M is finished and came out beautifully (in terms of the rolloff shape, IR and CSD). The high pass filter for the Radian 745 is in progress. The circuit has been simmed but not yet built. I was waiting for some autoformers and custom inductors from dave slagle (Intact Audio) and other various parts, but everything's here now. I will have a chance to put them together and run some tests this weekend.

With any luck, I'll get to hear some music through them very soon! (getting tired of test signals...)

Gary Dahl