2 way bookshelf with AT-15H Cquenze and Scanspeak D3004 Beryllium dome

[chlorofille]

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.

[David Gatti]

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.

[chlorofille]

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.

[chlorofille]

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 :

[5th element]

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.

[5th element]

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.

[chlorofille]

Yes you are right. It will merely smooth the response slightly from 1-5Khz.

[chlorofille]

Originally Posted by 5th element

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.

[boris81]

The Edge software can simulate BSC for odd shape baffles.
It's free and very easy to use.

[chlorofille]

Thanks Boris.