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Multi-Way Conventional loudspeakers with crossovers

The "Elsinore Project" Thread
The "Elsinore Project" Thread
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Old 23rd August 2019, 12:39 PM   #2531
Joe Rasmussen is offline Joe Rasmussen  Australia
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Quote:
Originally Posted by mbrennwa View Post
That may be a silly question, but what does this plot really show? I assume it's some kind of SPL, but... anechoic? In-room? At which drive voltage? Where's the microphone (distance, level, on/off-axis)? Why is it "stepped"?
This is what is called an RTA measurement and it is definitely not anechoic. It is an in-room measurement.

The measurement is about 2.5 metre and about 15 degrees off axis. The Elsinores should be listened to off axis. If the room is a bit dead, then toe them in, if the room is a bit bright, do the opposite. For the most time, when sitting down in the optimum position, you should see some of the insides of the boxes.

Most RTA measurements are 1/3rd Octave and hence the steps. This is a 1/6th Octave and gives a lot more resolution. The stimulus is Pink Noise.

Below was posted earlier on and you can see all the room modes:

Click the image to open in full size.

The peaks and the valleys are OK, so this is a pretty good result. The further you go below 1KHz, the more influence room modes will have.

Above 2KHz the result becomes closer to what we would expect in an anechoic chamber.

Definitely voltage drive, but the Elsinores will not deviate even with current drive. It would look the same because the Elsinores draw the same current at all frequencies and that takes the high impedance of current drive out of the FR equation.
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"Elsinore Project" DIY Speaker System
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Last edited by Joe Rasmussen; 23rd August 2019 at 12:43 PM.
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Old 23rd August 2019, 02:30 PM   #2532
mbrennwa is offline mbrennwa  Switzerland
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The "Elsinore Project" Thread
Quote:
Originally Posted by Joe Rasmussen View Post
This is ... an RTA ... in-room measurement.
Ah, ok. I was thinking I might be able to extract some information about the efficiency of these loudspeakers, but I guess these RTA curves are not very meaningful for this. I found it a bit surprising that the Elsinores are > 90 dB down to about 45 Hz (as shown here), but then I realised that this plot does not say what voltage/power was applied, and at which distance the measurement was done. Can you provide some insight?

I have recently read a few things about in-room SPL curves. The gist seems to be that smooth, but sloping curves with lower SPL at higher frequencies are preferred. How does that relate to the Elsinore?
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Old 3rd September 2019, 01:05 PM   #2533
dmcgown is offline dmcgown  United States
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Default Progress!

Over the long weekend, finished cutting my panels and then routed out the baffles, baffle brace and main brace for the cabinets. Instead of using a jigsaw, made an adjustable router template to make the rectangular cuts in the baffle brace and main brace. Worked great, but it did take alot of time. Very close to starting glue-up of the cabinets.

David

Last edited by dmcgown; 3rd September 2019 at 01:15 PM.
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Old 3rd September 2019, 02:51 PM   #2534
dmcgown is offline dmcgown  United States
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Picture of progress.

20190902_154121sm.jpg - Google Drive
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Old 3rd September 2019, 03:34 PM   #2535
dmcgown is offline dmcgown  United States
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More pictures showing progress, as well as my press for laminating two pieces of MDF together.

Still learning on posting images. All I seem to be able to do is post links.

20190818_121015.jpg - Google Drive

20190818_120950.jpg - Google Drive

20190818_120940.jpg - Google Drive
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Old 3rd September 2019, 04:28 PM   #2536
BYRTT is online now BYRTT  Denmark
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The "Elsinore Project" Thread
Quote:
Originally Posted by dmcgown View Post
Quote:
Originally Posted by dmcgown View Post
More pictures showing progress, as well as my press for laminating two pieces of MDF together.

Still learning on posting images. All I seem to be able to do is post links.

20190818_121015.jpg - Google Drive

20190818_120950.jpg - Google Drive

20190818_120940.jpg - Google Drive
Instead of using links its best to upload to diyA server so images will stay forever and never disapear should that link ever change into future, example is below : )

Pick the advanced dialog to make posts because it have will have a clip icon at top middle where one can upload pictures, prepare that images is physical avaiable on one of local computers fixed or removeable harddrives because upload dialog can only point to drive letters, one can upload up to 10 attachments per post in one go, but if image size is bigger than 976.6 KB then don't use one go but instead upload one at a time using the "Upload" button seperate for each new image string, this behavour is because it looks diyA server can downsize if they too huge but works only picking one at a time and fails picking multiples.
Attached Images
File Type: jpg 20190902_154121sm.jpg (419.6 KB, 274 views)
File Type: jpg 20190818_121015.jpg (671.0 KB, 254 views)
File Type: jpg 20190818_120950.jpg (604.5 KB, 249 views)
File Type: jpg 20190818_120940.jpg (546.3 KB, 245 views)
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Old 3rd September 2019, 04:31 PM   #2537
dmcgown is offline dmcgown  United States
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THANKS!!!
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Old 3rd September 2019, 04:35 PM   #2538
zman01 is offline zman01  Bangladesh
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The "Elsinore Project" Thread
dmcgown,

Good to see the build progressing.
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Old 3rd September 2019, 04:45 PM   #2539
bartosz37 is offline bartosz37
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Quote:
Originally Posted by Joe Rasmussen View Post
Yes, I would go along with that comment. As far as distortion is concerned, I have done tests on individual drivers in the past, but I have not compared NRXC and MFC in that regard. But they are clearly very good. Where I have paid most attention in the overall design, that comes to the tweeter. To me that has often been the Achilles Heel. I have done comparative tests on the HDS tweeter versus a top-of-the-line Scan-Speak tweeter (the HDS is also made by Scan-Speak, but that was not well-known then).

Take a look at this link:

LINK: TWEETER COMPARISON

The Waveguide and the use of the null technique, ensures very low distortion of the tweeter, along with the Waveguide. I use the Waveguide to lower distortion, where other use it to extend bandwidth and cross over at a lower frequency. I resisted that temptation, I wanted less distortion, period!

The use of a single inductor on the other drivers, here I am willing to trade imperfection, in order to keep the current straight and also because a single inductor suppresses the internal non-linear inductance of the driver. But clearly, to be able to do that you have to be very driver selective.

It's been near twenty years ago that Lynn Olson (who has agreed that we have some similar approaches) wrote the article, link below. It is quite long and very detailed, but still surprisingly current and applicable to even today.

LINK: The Family of Direct Radiators by Lynn Olson

For those interested, that will keep you occupied for some time.
Hi Joe,
I was wondering. Why higher (around 3 kHz) x-over point has lower distortion than lower (around 2 kHz). I thought that if tweeter has lower distortion than midwoofer, widening tweeter frequency response will lead to overall lower distortion. Is it because tweeters Fs is not that far away from 2 kHz x-over point?
I was also taking into consideration fact that a crossed higher midwoofers breakup would beam more even though it has RLC trap. What are your thoughts about crossing around 2 kHz?
Best regards,
Bartosz
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Old 5th September 2019, 08:45 PM   #2540
Maxim yaroslavl is offline Maxim yaroslavl
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x-over point on 3 kHz?
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