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Any chance to modify HDT right for 10" drivers? (Read 1807 times)
hebrer
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Any chance to modify HDT right for 10" drivers?
08/17/10 at 13:34:00
 
I have been wishing to build HDT speakers for some time and now I have a pair of 10" Audio Nirvana cast frame drivers. I really like the design principles behind HDT and would like to explore if it is possible to modify it for the 10" drivers...

With only one DIY speaker project under my belt (Metronomes with 4.5" Fostex drivers), I would appreciate your opinions if this modification of HDT to 10" drivers can be done and how to go about it... I am decided to use the drivers in full-range configuaration without any additional tweeter or subwoofer.

Any thoughts on this are much appreciated.

Peter

Technical specifications of the drivers: commonsenseaudio.com/an10cfspecs.jpg
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hebrer
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Re: Any chance to modify HDT right for 10" driver
Reply #1 - 08/20/10 at 11:13:54
 
I guess nobody went this direction before...

Would you say that simply increasing all measurements in the plan by 20 percent (except the thickness of the building material) would bring:
(a) uneven and unpredictable results
(b) behavior of the cabinets very similar acoustically to the smaller one
(c) N/A - you recommend not to do this.

Thanks for your opinion.
Peter
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« Last Edit: 08/20/10 at 11:14:32 by hebrer »  
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dank
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Re: Any chance to modify HDT right for 10" drivers?
Reply #2 - 08/20/10 at 14:51:25
 
You're fighting a couple of things here...First is nobody knows what Audio Nirvana's (of any size) sound like in an HDT.  Second, the Audio Nirvana has a fairly large frame (outside dimensions?) so it may require more room to mount than other 10" speakers.  Third is that the HDT, from what I've gathered, is somewhat complex inside and may not be as forgiving as other speaker boxes to small changes in the dimensions.  

Just off hand, I would say that it is not a good idea to simply scale everything up by 20%.  If you had a 10x10x10 box and scaled it up by 20% you get a 12x12x12 box.  But the volume changes from 1000 to 1728 or up 72%.

I'd be much more inclined to do as little change as possible to squeeze the 10" speaker in there, but I'd be even more inclined to try and find out if you like the way Audio Nirvanas sound in an HDT first.

What size speaker is normally in a HDT?  What is its Vas, Fs, and Qes?  For the cast 10" Audio Nirvana, I see Vas = 173L (6.1 cubic feet), Fs = 34.2 hz, and Qes = .275.  If the stock HDT speaker varies considerably from any of these parameters, I'd proceed with caution.

Dan
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hebrer
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Re: Any chance to modify HDT right for 10" driver
Reply #3 - 08/20/10 at 18:38:25
 
Thanks, Dan. Your answer is helpful to an enthusiast newbie like myself.

As for the driver used in the original HDT, I just assume it is this one:
http://www.decware.com/newsite/DFR8.htm

with QES=0.23 and VAS=54 ltrs.

I am trying to get a feel for what to expect in case of bad synergy between the driver and the cabinet - peaks in frequency spectrum? Poor soundstage? Would the potential drawbacks be something that can be fixed with some experimentation (longer or shorter pipes, damping) or would the problems be beyond repair?

I am curious about "audio nirvana" sound instead of "fostex" sound - even though I had built my own Metronomes using Fostex 4.5" eNabled drivers and enjoy the results. I can see why Fostex was chosen as the default driver for HDT. The thing is I wish to try to build 10" fullranger and AN drivers get good reviews from those willing to work to achieve synergy with the cabinet.

Obviously, if there is just too much risk involved that AN in HDT would be unlistenable no matter how much tweaking, then it is better to invest energy in other designs... This is my dilemma and - when I am done with the building - other people might benefit from direct report on this combination.
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« Last Edit: 08/22/10 at 08:58:53 by hebrer »  
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