High efficient subwoofer design

Status
Not open for further replies.
Jump to Latest
#61
Thanks for all the good info again Scott..... The Reckhorn it is... I take it from the paper that you linked, that push-pull is ok? I didn't understand so much as it didn't really seem to compare push-pull to push-push isobaric and push- push is the design were going after?? Dave🙂
 
#62
DaveCan said:
Thanks for all the good info again Scott..... The Reckhorn it is... I take it from the paper that you linked, that push-pull is ok? I didn't understand so much as it didn't really seem to compare push-pull to push-push isobaric and push- push is the design were going after?? Dave🙂
Click to expand...


In fact all are actually push-push (physically speaking that is).

The net result of the clamshell vs. the more normal version is rarely a decrease in even-order harmonics unless the volume between the two drivers is virtually non-existent. Even then though, the distortion levels were not significantly reduced.

Of course a clamshell with only a minimal "ring" divider to separate the two driver's for excursion - is a virtually non-existent volume. So you *could* have the potential for at least some benefit with the clamshell configuration.
 
#63
ScottG said:


You could have grounding issues with that type of hookup. The best solution is to spit-out your pre-amp's output.. sending one grouping of rca's to your amp and the other to your sub amp.
Click to expand...

note that "spit-out" should read SPLIT-out.😀 :clown:

("..so which is it baby, spitz or swallows?" Austin Powers.)
 
#66
DaveCan said:
Wow, that is a good price.. Have you had any troubles ordering direct from HK? I guess I'd worry about if the unit arrives damaged it's a long haul back and forth again... Dave🙂
Click to expand...

VERY good price! 😀

I haven't ordered from HK before.. but,

Brian is good people - if I have a problem I'm sure he will fix it.

Here is their forum.. ask previous customers:

http://www.audioasylum.com/forums/DIYHiFi/bbs.html
 
#68
DaveCan said:
Hmmm very tempting.... Are you doing a new project soon or adding the Reckhorn to what you already have? Dave🙂
Click to expand...

No project or even an addition - just a really good deal for a limited time. (..Sure at some point I'll play with it, and likely the basic design discussed here. - though I do have other drivers to try out with it.)
 
#69
I've sent an e-mail to CSS to see if they have any discounted stock or if the units will go on sale soon. I told them about the good deal and linked the site so hopefully they can'' make a deal''. If not I'll put my order in at diyhifi..... Dave🙂
 
#70
DaveCan said:
I've sent an e-mail to CSS to see if they have any discounted stock or if the units will go on sale soon. I told them about the good deal and linked the site so hopefully they can'' make a deal''. If not I'll put my order in at diyhifi..... Dave🙂
Click to expand...


Sounds like an excellent plan to me.

(Note that Bob Reimer of CSS and Brian Cherry of DIYHIFI are both members here.)
 
#71
ScottG said:



Sounds like an excellent plan to me.

(Note that Bob Reimer of CSS and Brian Cherry of DIYHIFI are both members here.)
Click to expand...


Thanks I didn't know that... CSS is close to where I am, within a 100km I think so the shipping would be much less...

Got an idea for the cab, I figure 17''x17''x 30'' internal = 5.017 cuft.

Then I was thinking of making a second smaller custom cab to fit over the driver in the 5cuft cab, so then I can easily load the 2 drivers push, push isobaric and then also be able to flip the cab over and now I got clamshell push pull😀 Dave🙂
 
#72
DaveCan said:



Thanks I didn't know that... CSS is close to where I am, within a 100km I think so the shipping would be much less...

Got an idea for the cab, I figure 17''x17''x 30'' internal = 5.017 cuft.

Then I was thinking of making a second smaller custom cab to fit over the driver in the 5cuft cab, so then I can easily load the 2 drivers push, push isobaric and then also be able to flip the cab over and now I got clamshell push pull😀 Dave🙂
Click to expand...


Not bad!😉

Remember to get maximum effectiveness from a clamshell requires as little volume between the drivers as possible.

Also, don't forget that you'll need 2-3 inches of space between the cabinet and the floor. And IF you have carpeting then you might want to consider a floor plinth so the driver "fires" down to a smooth surface.

Oh and irregularly placed dowels used as side-wall bracing not only tend to work better than normal cabinet construction bracing, but they also are much less restrictive on air flow and reduction in volume.

(..basically pre-drill holes in the cabinet side walls (and dowel-ends) for the screws where the dowels will be connected - then screw them in place and then Spackle them with Bondo and sand it down.)
 
#73
Great idea about the dowels, I'll do that thanks...

Bob from CSS returned my e-mail and said that the A400 from HK are the earlier versions which don't have the full output at 2ohms (confirmed by one of the German diy audio magazines), and also have the sat x-over freq limited to 150hz.. He has one of the earlier versions left and offered a great deal, so I'm going to go for it also.. He said in the new year there will be a new black model the 401 he thinks... Anyhow looking forward to putting all this together soon... Dave🙂
 
#74
DaveCan said:
Great idea about the dowels, I'll do that thanks...

Bob from CSS returned my e-mail and said that the A400 from HK are the earlier versions which don't have the full output at 2ohms (confirmed by one of the German diy audio magazines), and also have the sat x-over freq limited to 150hz.. He has one of the earlier versions left and offered a great deal, so I'm going to go for it also.. He said in the new year there will be a new black model the 401 he thinks... Anyhow looking forward to putting all this together soon... Dave🙂
Click to expand...

Cool (..hope you got an even better deal than I did)!

Neither limitation should be a problem..

1. The design was for a SUBWOOFER, not a midbass module - so the 150 Hz vs. the 300 Hz for the high pass is pointless. In fact any high pass at all is likely pointless (..well, depending on how "full range" your loudspeakers are).

2. You probably wouldn't want to "sink" more than a nominal 32 watts at 8 ohms - lest you potentially exceed the driver's mechanical limits in this design.
 
#75
Yes he offered a great deal but hasn't gotten back to me yet so I hope it's still on? $225.00 includes shipping😎

I wasn't bothered either about the specs as I'm not planning on using that feature, I'll leave my mains getting the full meal deal, only working with 6wrms anyhow... Dave🙂
 
#76
Scott,
Talked to Bob from CSS on the phone yesterday and he said that the earlier version of the A-400 doesn't make the claimed power into 2ohms but is stable no prob at 2ohms... The 4ohm and 2ohm rated specs are the same he said... That didn't bother me either so I put a check in the mail and ordered it... Dave🙂
 
#77
DaveCan said:
Scott,
Talked to Bob from CSS on the phone yesterday and he said that the earlier version of the A-400 doesn't make the claimed power into 2ohms but is stable no prob at 2ohms... The 4ohm and 2ohm rated specs are the same he said.
Click to expand...


Thats often the case.

What happens here is that IF the output stage can handle the drop in impedance - then its left solely up to the power supply to feed that output.

The very best (solid state) amplifiers usually have MASSIVE power supplies that provide a full doubling of power as the impedance is halved. (i.e. 100 watts 8 ohms = 200 in 4 ohms = 400 2 ohms.)

Its quite rare in home audio to have an output stage that can handle a 2 ohm load (or rarer still a 1 ohm load). And even those few that can usually have a power supply that is insufficient to meet the full linear output of the output stage.

Thats the case here. A good output stage with a slightly deficient power supply.

Fortunately for this application though, that additional power into 2 ohms isn't needed (..even with a 2 ohm load from an additional sub wired in parallel).

BTW, you'll probably receive yours long before mine.. shipping for mine is literally on a slow boat from china (..which suits me fine, as I'll be on vacation over the holidays and don't want something showing up on my doorstep then).
 
#78
I have to thank you for letting me know the deal from HK... I would have probably missed CSS last one of that version as I wasn't in a hurry to order the amp yet...

Last night I had such a wonderful listening session and wondered why I am wanting to add a sub.. The little Fostex fe108ez's in the BIB cabs provide a very nice quality bass, but I know I do miss some low information. Anyhow will be a fun project to do and I'm looking forward to it... Dave 🙂
 
Status
Not open for further replies.
Top Bottom