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Multi-Way Conventional loudspeakers with crossovers

3-way open baffle plus subs
3-way open baffle plus subs
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Old 7th September 2020, 11:07 AM   #41
LewinskiH01 is offline LewinskiH01  Argentina
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Quote:
Originally Posted by Juhazi View Post
Why is mic so high in Edge sim? There is cancellation because of vertical source distance showing. This is real, but I wouldn't design anything based on that. Always take on-axis sim first to see "ideal" response. Off-axis sims are useful to find out where and when directivity gets messed up.

Attached is my sim with mic on mid-driver height and above it like in Lewinski's sim.
I was simulating closer what real conditions would be, but I see your point. Thanks for taking the time to provide a thorough answer.

Quote:
I wouldn't lowpass above 800Hz, too much variations above 1kHz!
You mean low passing the 10", correct? I was thinking lower, like 300Hz, but your comment is making me think it would maybe be too demanding on the midrange. 600Hz would reduce by 8x the excursion demanded at 300Hz so no small difference. Eventually I will check how music sounds in that region played by the 8" vs. the twin 10".

What's your view on the value of making these measurements indoors? With speakers standing on the floor? How should the be made to make them as valuable as possible?
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Old 7th September 2020, 12:06 PM   #42
Juhazi is offline Juhazi  Finland
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Yes concidering where to cross and what order is complicated, especially with dipoles. With dsp it is very easy to try different settings and minidsp can save four on presets. Then listening tests and distortion wiht high spl!

Measuring indoors below say 800Hz is conmplcated always. Speaker diagonally at least 2m from sidewalls and on a stand measured at 1m gives lowest reflections and is ok for mid up and setting crossovers and timing. But even then below 400Hz or so is a mess.

Ground plane with long gating 60-100ms will help with bass, combined with nearfield longer gate. Nearfield misses baffle effect and most importantly dipole summation, so that must be kept in mind. Guide to ground plane outdoors but indoor at 1-2m is better than nothing too.

Listening position measurement of both speakers individually with 500ms gating is needed to find gain for each driver/way. Many people eq the lowest room mode too, but not me.
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Old 7th September 2020, 01:01 PM   #43
LewinskiH01 is offline LewinskiH01  Argentina
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Thanks for the links. Will look into them tonight.

Trying different crossovers will be rather easy in my set up: I use Acourate to derive digital xo and room correction, so can test different xo points/types/slopes and try them until my heart's contempt . Acourate will also take care of matching gains for each driver, and those measurements are taken at listening position indeed.

With boxed speakers one would usually linearize driver response with Acourate by taking very nearfiled measurements, but with OB it doesn't make sense to do that, as you pointed. Then one would run the final measurement from the listening position at ear-height. Acourate reduces the response down to a target curve defined by me. I wonder how applying 15dB reduction (or more) will sound. I guess the way to know is to try it.

All of the above will happen when I have the system reconfigured. For now I'm testing drivers individually to understand if this has any chance of succeeding. Seems like 2x10" up to about 600Hz and 8" baffleless up to 1500Hz could work. Correct?

I need to look into incorporating the TPL-150H. StigErik concluded TPL-150 were too large for proper dipole operation and moved to a smaller Mundorf and eventually RD75. I'm sticking to TPL for now. I'm leaning to keeping the waveguide on. With factory back chamber, enlarged closed chamber, open back? Opinions very welcomed!
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Old 11th September 2020, 05:07 PM   #44
Draki is offline Draki  Macedonia
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Quote:
Originally Posted by CharlieLaub View Post
.

Here is what you do:
  • Take a nearfield measurement of the response from the front
  • Take a nearfield measurement of the response from the rear
  • Find the front-to-back pathlength
A practical question: if the front NF is measured close to the apex of the dustcap (assuming no phase plugs etc), then at which position do you measure the rear NF? What if it is a U-frame with full-depth stuffing/damping?
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Old 28th September 2020, 10:54 PM   #45
LewinskiH01 is offline LewinskiH01  Argentina
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Made some progress. I had an issue with my soundcard which took a fair amount of time to figure out it was a hardware issue only affecting two channels, so I was able to circumvent the issue and measure using other channels.

Anyway, here's where I stand: built one speaker, playing mono.
Two 12" sealed subs play up to 70Hz
Two 10" OB from 70 to 500Hz powered by the Hypex UcD amp (the low gain in these amps forced me to re-route soundcard channels as not all of them have the same gain)
Swinging 8" bafleless from 500 to 1500Hz powered by one channel in MC275
TPL-150H with back cover as sold by Beyma from 1500Hz up, powered by MC275.
XO: NT 2nd-order. Digital XO and filters generated in Acourate.

20200928_193004.jpg

Sounding good. Many things to try out, though. I turned the speaker around 90 degrees and opened the dividing panels so the room is now 10m long and speakers are 3m away from the [now] front wall and 7m from the back wall.

Fun!
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Old 29th September 2020, 01:26 PM   #46
Juhazi is offline Juhazi  Finland
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The Beyma TPL has no backside radiation at all and high directivity. This is a huge difference to having dipole pattern 70 1500Hz in a room!

In a room we hear also reflected sound as part of total sound pressure/room response. An additional backside tweeter will help a lot to get sound balance right and to give similar "3D presentation" of stereophonic imaging.

Here my horn tweeter version of AINOgradients with and without backside tweeter - at listening spot/on-axis. Crossed around 3500Hz and it was very easy to hear the difference! On-axis response was not equal in these measurements, but I had numerous settings tested and the backside tweeter stayed until I purchased B&G Neo3 planar dipole tweeters.
Attached Images
File Type: png ainogneob v2 vs neo v11 0¤ decay csd.png (761.5 KB, 102 views)
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Last edited by Juhazi; 29th September 2020 at 01:29 PM.
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Old 29th September 2020, 06:32 PM   #47
manninen is offline manninen  Finland
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When i had tpl´s with open back midrange i had back cover off, but i didn´t take the felt off.

yeah, it was better balance without cover
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Old 29th September 2020, 06:40 PM   #48
scottjoplin is offline scottjoplin  Wales
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Without the rear radiation there will be no null and early reflections from the side walls will be spectrally out of balance.
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Old 29th September 2020, 09:20 PM   #49
AllenB is offline AllenB  Australia
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3-way open baffle plus subs
It might not be so bad. The TPL has plenty of directivity with the back on.

I'm not convinced that the cross to the B&C won't work because with the size of the magnet what is going to be happening at 1k5? Theoretically the DI would be out by 6dB but in reality I'd want to see measurements. What about felt behind the mid to gradually blend it toward forward radiation only at its top end?
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Old 29th September 2020, 10:49 PM   #50
LewinskiH01 is offline LewinskiH01  Argentina
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Quote:
Originally Posted by Juhazi View Post
The Beyma TPL has no backside radiation at all and high directivity. This is a huge difference to having dipole pattern 70 1500Hz in a room!

In a room we hear also reflected sound as part of total sound pressure/room response. An additional backside tweeter will help a lot to get sound balance right and to give similar "3D presentation" of stereophonic imaging.
One of my next steps is to take the back cover off in the TPL and use it as dipole. Long time ago StigErik was using the TPL in this fashion, although without the horn, and spoke highly about it. Eventually he concluded the TPL was too large and moved on to B&G Neo 3 dipoles too.

I'm not sure what to take away from the plots you attached. The top graph is with back tweeter and longer decay?
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