Falconsprint's RAAL/Accuton/DEQX project - diyAudio
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Old 27th March 2013, 06:06 AM   #1
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Default Falconsprint's RAAL/Accuton/DEQX project

Some of you might remember my other thread looking for suggestions on drivers to match with the RAAL 140-15D tweeter. I received a lot of good feedback and it has had an influence on the decisions I've made so far. Thanks everyone. This thread is to track progress and get comments and suggestions.

I gave up on trying to build a full-range 3-way and decided to build a 3-way with subwoofers. I was able to pick up a used deqx pdc-2.6p to link to my hdp-4. It controls the subwoofers.

I choose the Accuton C173-6-090 for the midrange. I was originally concerned that the driver would be too large to equal the horizontal dispersion of the RAAL. But the smaller Accuton midranges didn't look like they would be able to produce the SPL that was necessary for a music/HT speaker. I considered a MTM setup, but was advised not to go that route due to the large separation the 7" RAAL tweeter would create.

As you can see from the photos attached I've mounted the RAAL and Accuton in a Dayton Audio MTM enclosure. I've then used the two 8" woofers from my NHT M80s. As I stated in the previous thread, I wanted an interim solution while I take the time to build the full size 3-way enclosure. I've tried a TMWW alignment and MTWW. I prefer the MTWW (final picture) as it creates a taller soundstage in my room. Cross-overs are at 400hz and 2000hz, both at 96db/octave (deqx default). The subwoofers are crossed over at 80hz 24db/octave. The results so far are fantastic. A significant upgrade from the NHT M80s I was using before (which were also very good).

So now I'm ready for the next steps. Choose a woofer and design a 3-way enclosure. I leaning towards only having a single woofer, covering 80hz-400hz. Having a single driver will result in more accurate measurements for the deqx. A single woofer, especially with a MTW alignment keeps the woofer off of the floor, reducing reflections. The other important benefit is it keeps the drivers out of harms way from the dog. My current thought is the 8" Accuton C220-6-222. I'm so happy with the ceramic midrange that I wanted to stay ceramic and also get the efficiency of the neodymium magnet. I could go with the 11" Accuton S280-6-282, but I don't think it is necessary with a HPF at 80hz.

I'm looking for some verification on my choices for enclosure volumes. I sub-divided the Dayton Audio enclosure to get the midrange volume down to about 5.5L. I'm probably going to redo it and make it smaller (4.5L) and with an angled back wall. I'm put some polyfil in the enclosure. But maybe it would be better to take that out and replace it accoustic foam attached to the interior walls. For the woofer enclosure I am looking for recommendations from someone who can simulate the driver with a speaker design software for my target of 80hz. I'm only considering sealed enclosures since measuring a ported enclosure with the deqx is problematic.

Once the enclosure volumes have been decided I will sketch out some box designs. I would like to stay with the MTW alignment unless someone can convince me otherwise.

Also up for discussion is my choice in crossover frequencies.
Attached Images
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Last edited by falconsprint; 27th March 2013 at 06:13 AM.
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Old 27th March 2013, 01:58 PM   #2
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Lookin' good so far!

I'd use some some rigid fiberglass(A/C duct board) or Bonded Logic to line the walls of the top module. There's a reason real acoustic products do not use polyfill.

How's the Raal/accuton soundstage treating you? As good you'd hoped for?

Greg
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Old 27th March 2013, 03:18 PM   #3
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That looks great.
Nice selection of drivers, where did I see those before

With HPF at 80hz I think it's better to go with the the 8" Accuton C220-6-222 than the 11", with the 11" the distortion starts to rise at 700Hz (too close to xo at 400hz), with the 8" it's much higher at 1.5-2k.
The 8" has also a much lower mms of 27g compared to 65g for the 11", matches better with the mid.

For The Raal you could try some higher xo points like 2.5-3k,
The distortion levels of the Raal are much lower at 2.5-3k than 2k

Regards,
Danny
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Last edited by danny_66; 27th March 2013 at 03:38 PM.
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Old 27th March 2013, 05:37 PM   #4
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Quote:
Originally Posted by danny_66 View Post
That looks great.
Nice selection of drivers, where did I see those before
Regards,
Danny
Thanks Danny, yes I did get some inspiration from your project. The beauty of the deqx is that I can try out different cross-over frequencies and slopes. I've read some threads where the distortion of the RAAL at lower frequencies is discussed. I've tried 1800, 2100 and 2400 and to be honest I don't hear a difference. I'll set the deqx up for 2000,2500,3000 so that the difference may be easier to detect. I know that I'll also pick up some SPL if I crossover higher. But I already seem to have enough for my room.

I've pretty much decided on the 8" accuton. It will take 3 months for Madisound to get it. So plenty of time to design and build a cabinet. I'll be building 3 identical speakers for left/center/right and replacing my plasma with a projector.
-Dave
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Old 27th March 2013, 07:07 PM   #5
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Nice to hear, that I can be of some inspiration

When I developed my passive crossover I also used an active simulation setup for the first 30+ versions

Yep, that accuton mid is very nice, even driven loud without crossover it sounds good, no ear splitting sounds due to cone breakups. Nice !
I found that they need about 200-300 hours of play before they sound completely holographic.

Your setup will look great with the 8" Accutons, success !
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Old 27th March 2013, 09:18 PM   #6
tf1216 is offline tf1216  United States
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Congrats! You are moving a fun pace. Have you experimented with shallower slopes? In my days toying with an active crossover I found 6 dB/octave and 12 dB/octave were more pleasing to my ears. Things are only going to get better my friend.

Any drawings for your enclosure yet?
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Old 28th March 2013, 03:49 AM   #7
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All sounds like a good plan moving forward with the speakers.

I'd like to recommend for your smaller size room to consider a 70-80" LCD rather than a proj. Brighter, quieter, no bulb to replace, no wiring to run up and over your head. Only plus with a proj is that you could get an acoustically transparent(haha kinda, but not really) screen and hide the speakers behind it, but it seems that then the screen may be sticking too far out into the room.

I hang a lot of screens and proj for my regular, day job and most people are preferring a larger display rather than proj nowadays if it's under say 100"

Greg
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Old 28th March 2013, 12:18 PM   #8
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Hi, Falconsprint. I advice you not to go with 2 subwoofers and room correction on deqx. Read papers written by Dr Welti and Dr geddes on multisubwooofer arrangement (at least 3 or 4). Get rid of all nasty modes then do global room correction on Deqx. You dont need an expensive second DEQX. My route is to use DEQX for 2-way monitors plus inexpensive Behringer DCX2496 to time allign subwoofers (up to six). I do have two deqx but I think it is a waste of money. You dont need HQ sound from woofers after all.
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Old 28th March 2013, 12:19 PM   #9
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Here you have some info on the topic:
Using multiple subwoofers to improve bass: The Welti / Devantier and Geddesapproaches - Blog - Acoustic Frontiers
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Old 28th March 2013, 12:25 PM   #10
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Here is an interesting discussion about changing a little this approach and use 2 subwoofers as helper ones in transition frequency region beetwen <150 Hz and 1-3 more to take advantage of Welti approach below 80 Hz

AudioRoundTable.com: Pi Speakers => Flanking Subs vs Helper Woofers
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