2 way bookshelf with AT-15H Cquenze and Scanspeak D3004 Beryllium dome - diyAudio
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Old 27th May 2011, 03:26 PM   #1
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Default 2 way bookshelf with AT-15H Cquenze and Scanspeak D3004 Beryllium dome

Hi guys,

For my current 2 way bass reflex bookshelf speaker, I will be using :

1. Audio Technology 15H Cquenze 5.5'' midwoofer
2. Scanspeak Beryllium dome tweeter D3004

The enclosure will be made of stacked Finnish WISA Baltic birch plywood panels to form an internal volume of 9-15L. One speaker will consist of 10-15(depending on internal volume chosen) panels of Part B, one front panel (Part A) and one back panel (Part D). Part C will not be used. As part of assembly, the panels will be clamped together temporarily so that testing of different volumes can be achieved.

Per Skaaning has suggested to crossover as high as possible using a first order for the woofer. With the help of Xover pro, the rough crossover slopes and values will be obtained, and then I will purchase some components to test. Tweaking (at this stage) will be done by ear as I don't have the CLIO measuring program yet.

The speaker will be driven by Rod Elliot's P3A amp and Pavel Macura's PRE3 preamp.

The features of the enclosure :

1. Variable wall thickness
2. Non parallel walls
3. Minimal damping

Tony (Musik007) is doing the CNC machining for the panels and will update once the panels arrive.
Attached Images
File Type: jpg Speaker enclosure made of stacked MDF panels.jpg (32.4 KB, 845 views)
File Type: jpg speaker enclosure.jpg (13.2 KB, 814 views)
File Type: jpg AT-15H C quenze3.JPG (119.5 KB, 810 views)
File Type: jpg AT-15H C quenze2.JPG (124.7 KB, 791 views)
File Type: jpg AT-15H C quenze.JPG (178.9 KB, 785 views)
File Type: jpg D3004 Top.JPG (131.8 KB, 108 views)
File Type: jpg D3004 rear.JPG (174.3 KB, 165 views)
File Type: jpg Be recycling guide.JPG (126.9 KB, 177 views)
File Type: jpg DSC_6750.JPG (200.5 KB, 280 views)
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Old 2nd June 2011, 05:17 AM   #2
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Very tasty.

I've used the Cquenze 15h myself at was extremely impressed with its neutrality.
I would try to cross it in the 3-4kHz range or you'll lose a little presence. I found that a gentle notch filter was necessary around 5.5kHz.

What crossover slope are you using on the tweeter?

Will be interested in your listening impressions. Please dont blow up that tweeter.
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Old 2nd June 2011, 11:23 AM   #3
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Hi David, thanks for your suggestion. I plan to use a 6dB/oct crossover @ 3Khz with a notch filter centred around the resonance peak (500Hz) of the tweeter. That would cause the rolloff to be slightly greater than 6db/oct. What tweeter did you pair your C-Quenze with? Am still waiting for the panels to be sent so will take some time before I can actually build them up.
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Old 2nd June 2011, 02:26 PM   #4
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Here is a "stock" L-R 2nd order crossover @ 2Khz which will be used as a starting point, which works quite well for most Scanspeak drivers I have used in the past. The 15H C-Quenze is quite sensitive in the 250Hz - 1Khz region (90dB) and starts to climb smoothly by 8db to it's breakup point @ 5.5Khz. Doubt an L-Pad will be required for the tweeter (88dB/1m/W).

With the crossover, the 5.5Khz peak will be 15dB down, but in reality could be around 10db down.

Using a 12L bass reflex tuned to 48Hz, with a 50mm port 180mm long, the results(bass box pro) are a follows :
Attached Images
File Type: jpg L-R 2nd order crosover.jpg (89.6 KB, 282 views)
File Type: jpg simulated crossover slopes.jpg (33.5 KB, 139 views)
File Type: jpg AT response.jpg (47.9 KB, 113 views)
File Type: jpg AT 15H Cquenze in 12L bass reflex tuned to 48Hz.jpg (103.7 KB, 105 views)
File Type: jpg AT 15H Cquenze in 12L bass reflex tuned to 48Hz Part 2.jpg (102.4 KB, 71 views)
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Old 2nd June 2011, 02:32 PM   #5
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Do please bare in mind that a first order electrical filter @ 3khz, won't result in a first order acoustic slope on the C-Quenze unit.
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Old 2nd June 2011, 02:34 PM   #6
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It would appear that you haven't factored in any baffle step compensation to that simulation either. This will knock ~4dB off of the mid/basses sensitivity.
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Old 2nd June 2011, 02:35 PM   #7
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Yes you are right. It will merely smooth the response slightly from 1-5Khz.
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Old 2nd June 2011, 02:47 PM   #8
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Quote:
Originally Posted by 5th element View Post
It would appear that you haven't factored in any baffle step compensation to that simulation either. This will knock ~4dB off of the mid/basses sensitivity.
Hi, what baffle width(mm) do I use for BSC calculations? As it is a pyramid shaped baffle, it varies from 300mm to 100mm.
Attached Images
File Type: jpg front baffle.jpg (69.2 KB, 100 views)
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Old 2nd June 2011, 04:49 PM   #9
boris81 is offline boris81  United States
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The Edge software can simulate BSC for odd shape baffles.
It's free and very easy to use.
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Old 3rd June 2011, 01:55 AM   #10
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Thanks Boris.
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