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Multi-Way Conventional loudspeakers with crossovers

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Old 12th April 2018, 10:16 PM   #31
planet10 is offline planet10  Canada
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We went thru this when devoping the 1st mFonkens.

This was too narrow:

mFonken-protoTypes.jpg

This turned out OK (3rd try) but still not quite as “open” as the full-size Fonken:

bluegreen-mFonken.jpg

dave
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Old 13th April 2018, 09:38 AM   #32
lbstyling is offline lbstyling  United Kingdom
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Looking at the image, I'm guessing you have about an inch of space either side of the driver??

As the TD10M is now being used in the midrange only, and I would expect it to stay under 1mm xmax in use over 200hz, does this change anything?

I know Troels did some tests years ago on chamfering the driver hole on the back face, and he came to the conclusion that this reduced the 'cupping' sound.

However, this might actually be a desirable effect as its crossing to a horn with a narrower dispersion pattern....

I've asked for a quote for a tube to be made with a 18mm wall thickness at 330mm OD.

Another possible change to the design is to add a space to put interchangeable baffle covers on the mid driver. The aim is to have the option to play with pattern control on the mid a la JBL eon 615. I don't know if this raises distortion though.

YouTube

Last edited by lbstyling; 13th April 2018 at 09:48 AM.
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Old 13th April 2018, 06:01 PM   #33
planet10 is offline planet10  Canada
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Quote:
Originally Posted by lbstyling View Post
Looking at the image, I'm guessing you have about an inch of space either side of the driver??
Can’t findI had to dig deep to find the original drawing (a decade old document):

Prototype

tqwtl predictions-mfonkenproto-edgespace-png

Final:

tqwtl predictions-mfonken-edgespace-png

Quote:
… chamfering the driver hole on the back face, and he came to the conclusion that this reduced the 'cupping' sound.
Something we always do.

dave
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File Type: png mFonkenProto-edgeSpace.png (6.4 KB, 177 views)
File Type: png mFonken-edgeSpace.png (8.6 KB, 179 views)
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Old 16th April 2018, 11:11 AM   #34
lbstyling is offline lbstyling  United Kingdom
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I have found a manufacturer of card tubes that can make me a tube to specification. I have suggested a tube @ 360mm wide OD, with a 18mm wall thickness. This gives me 1.5 inches between the widest part of the frame of the driver (not the cone) and the outer wall of the enclosure. I hope this is enough not to colour the sound!!
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Old 16th April 2018, 11:19 AM   #35
lbstyling is offline lbstyling  United Kingdom
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I am concerned about how the sound will be affected if I go sealed with the mid driver, so plan to build the speaker in 2 stages.

The first is to run the speaker as a test rig with a removable back on the mid tube, so I can try sealed mid and ported mid/bass configurations.

And the second is to add the 2206h to the base cab and run the TD10m as mid sealed.

I should have enough room to make a semi B+W style enclosure tapering shape inside the mid tube when in the sealed format.

This will be interesting to play with, but also should give me some confidence that I'm making better choices.
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Old 8th June 2018, 10:44 PM   #36
lbstyling is offline lbstyling  United Kingdom
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An update:

I currently have the test rig speaker running with a digital active crossover (in JRiver)

I spent the last 2 days fiddling with crossover setting and levels. I wanted to see where I got too without using measuring equipment, just personal preference.

The TD10M is simply in a well damped (10 large towels, haha) 2m long open ended tube. Testing aperiodic, sealed and ported is very easy as I can just move a single MDF disc up or down the tube to change the volume of the box.

At the moment, the tube is open at the back (transmission line effectively) and just 50-60% stuffed. Moving the EQ bars up and down, its clear a hump at about 120/150hz is present, but not too bad.

interestingly crossovers ended up 1st order?! at:
350hz low pass to the AE TD10M
750HZ high pass to the JBL 2452.

I was surprised how much different orders of filter sounded. Perhaps something else is going on. I can hear what I assume is beaming when moving the bass driver crossover up further. Generally I am encouraged by what I hear. I don't have the 'SL' or aluminium diaphrams in the 2452, just the titanium ones, but they really don't sound bad at all! I was concerned it would have some 'horn honk', but the only time I have heard anything that I would imaging was like that it has turned out to be the audio track (confirmed by hooking up other speakers and headphones.
The TD10m delivers plenty of bass, However, my only criticism so far is I don't perceive it to be as dynamic as the JBL 2452 1.5 inch compression driver. Having said that, its still got WAY more of a punch than the 6 inch bass drivers I have been listening too the last few years! If this is improved further by going to a larger diameter bass driver, I can see why so many end up with massive 16 inch altecs, Addictive.

I plan to set up a pair of JBL 2206h drivers I have for running below 200hz and see what this does to the kick.

Tomorrow I will take some measurements to see how bad my ear tuned setup is!

Last edited by lbstyling; 8th June 2018 at 10:51 PM.
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Old 9th June 2018, 10:24 PM   #37
lbstyling is offline lbstyling  United Kingdom
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The following are measurements of my JMLC 350hz horn with 3D printed throat angle adapter for the JBL 2452H.

Image 1 is unsmoothed on axis at 1m measurement.
Image 2 is with 1/48 smoothing.
The third image is (spaced) the 1m measurements at:
0 deg
10 deg
20 deg
30 deg
40 deg

JMLC 2452H 1m on axis.jpg - Google Drive
JMLC 2452H 1m 0 deg 1-48 smoothed.jpg - Google Drive
JMLC 2452H 1m all.jpg - Google Drive

The next 2 are of the AE TD10M. (spaced and unspaced) They are simply in a 2m open ended tube, not a proper tuned box.

TD10M 1m All.jpg - Google Drive
TD10M 1m All unspaced.jpg - Google Drive
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