Cool didn't know that. They used 18db networks AMT-1 large Heil, The schematics are readilly availableIf you are proposing to continue with the Heil l suggest you email Nelson Pass at Passlabs on how best to set up the Heil. He previously worked in the R&D department at ESS when they introduced the Heil and build the crossover networks and has a wealth of expertise. He will respond.
http://esslabsusa.com/wp-content/upl...sedfinal-2.pdf
Rob
"I could be arguing in my spare time"
They made the Heil drivers. Hint: There was a fair bit of QC on them to meet production.
Originally Posted by pos
Should've listened to expert's advises then? I knew much less then than now and it is great learning experience. It is one thing to learn from reading, another level to actually do it and "feel" it.
Building your own diy speaker is very challenging. Most likely you will fail or it might take years. I recommend you clone an existing Jbl system and spend more time listening to the music.
Cloning an existing one is different. It is like building from a kit. I don't run into issues and won't learn from all the design issues and decisions made.
As for listening to music, well, that happens at the end of the days when I am tired from measuring and tweaking.
Your taking the comments too literally.
You are progressing but don’t get bogged down on one approach.
Don’t try and pre conceive the design as perfect on paper. It won’t be.
You are right about the first bit.
Everyone wants to build their own loudspeaker.
But be careful what you wish for.
It takes quite a while to perfect a loudspeaker you can live with and enjoy.
If you are prepared to do that keep going and listen to the hints.
My example was four years. Buying expensive components is no guarantee of it sounding any good.
Building from a Jbl design.
It depends on your level of knowledge, skill, resources and the complexity of the design. Building an M2 clone is NOT a kit. There is a lot to learn from a Jbl design.
Building a known design gives certainty that you invested in something that really works (the outcome) and certainly you will finish. People miss sight of that and it all ends up being sold off on EBay if it doesn’t come together.
KISS Keep it simple if you are doing it on your own
Btw have you looked at the Linkwitz web site.
Those are excellent projects.
Or get hold of a pair of HPD 15 Tannoys and put them in Imperial horns. That’s used as a reference by one of the most successful American Hi end audio companies.
I believe this is a major factor.
If the off-axis dispersion drops significantly below the crossover, this could cause a thin sounding midrange. In the first instance we would blame the horn to sound harsh or thin, but it´s the midrange-woofer that doesn´t distribute enough midrange energy off-axis into the room.
Using a wide-dispersion midwoofer (8-10") below the 2397 horn should match the dispersion well.
When using a 15" woofer a horn with narrower dispersion than the 2397 horn should match better...
Ok. I am convinced now that I should investigate further with the pair of 2123H that I have. Will do some dispersion measurement on those and compare with the 2216ND1 and see if that matches the 2397 better at 1kHz.
That combo works from own experience. It’s quite listenable. But l found it a double edge sword as the wider 2123 dispersion bounced off the 2397 lip causing a blurred sound (echo) on some program material. Any structure causes measured diffraction and reflection above 400 -500 hertz.
Nothing is perfect. It’s all about balancing the compromises.
This is a good thread on 2397.
http://www.audioheritage.org/vbullet...BL-2397-Curves
Have fun.
@Ian:
I believe I have asked you before, but do you remember the distance between the top of the 2123 and the bottom of the 2397 horn back then?
I imagine it would need a fair bit of distance to keep the reflections low...
If you take a look at the westlake audio BBSM-15 it has the 2123 very close below the horn. Maybe 3-4"...
The BBSM-15 doesn´t use a 2397 horn, but the horn protrudes just as much.
On the other hand the westlake audio HR-1 has the 2123 mounted with much more distance to the horn. Maybe 8-10"....
It’s not a valid comparison.
The adjacent surface area of the Westlake horn in question is much smaller than the 2397.
I noticed in one of your pics you were sitting the 2397 atop the enclosure.
This is common practice with audio amateurs.
Please be aware that Jbl provides baffle loading guidelines for the 2397.
My suggestion is to look up the 2397 data sheet to understand the guidelines.
Then cut a make shift loading baffle above below the 2397 and mount the baffles to the horn.
You might cut a slot in a sheet of 3/4 mdf to match the horn.
Then with the horn elevated at least 1.5 metres above any surface run an Frequency response and impedance curve and compare to the unloaded horn. Of course do a subjective test with an 800 hertz crossover point and 1200 hertz crossover point. You might find some of the issues you have had relate to the loading of the horn.
The data sheet says:
"Because of the action of the power distributors, the 2397 is notably free of high frequency beaming, and maintains its effective 140deg horizontal coverage to the highest audible ranges, with only minor lobes appearing above 5kHz. Vertical dispersion is largely dependent on the baffling; with the recommended cylindrical baffle extending at least 3 inches above and below the mouth, a nominal 60deg vertical beam width is achieved. These dispersion characteristics make the 2397 especially useful for overhead mounting in rooms with low ceilings."
a cylindrical baffle will be quite a challenge!
Regarding that, a little bit of progress has been made.
I was doing some measurements and while setting up, happened to play some music with just the 2216ND1 on. And while measurements shows little in terms of distortion, the 2216ND1 played up to 1kHz area is ear piercing, not sure if that's due to the beaming, or distortion, or what, but totally killed my ears. No wonder the 4367 crossover is at 700Hz.
construction for the 2123H enclosure is done. ran out of time to fire it up though. will do that this week.
Looking forward to hear your impressions
I would put a 3 sided flat baffle above and below then try
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