hehe.
A two hour plane ride from Vancouver and we'll be close to the panhandle.
Prince Rupert, British Columbia - Wikipedia, the free encyclopedia
For those of you considering a build of 24 in size or smaller, HD has some very nice cherry veneer 24 in x 48 in x 0.25 in thick plywood panels for $12.99 ea (Purebond brand). I am thinking of using this for my next build which will be a 24 incher, it seems that Bob was happy with his result in this size.
Happy Holidays everyone and hear back from you guys next year.
1/4 in. x 2 ft. x 4 ft. Cherry Plywood-1666 at The Home Depot
Happy Holidays everyone and hear back from you guys next year.
1/4 in. x 2 ft. x 4 ft. Cherry Plywood-1666 at The Home Depot
I know it's Christmas and you have better things to do that read this but I have to tell you something. My brother in law was asking about my latest forays into speakers and I showed him these threads. He was very interested.
They happen to have a Dollarama store here in this town of 12k and guess what?
Right!
He is now the proud owner of 25 sheets of foam core [still $1.25 a sheet], a new glue gun and plenty of sticks.
When I get back I am going to ask more opinions on the 20" unit as that is as big as he can go. He's a handyman so building will be no problem.
Time to get back to the Christmas celebrations so I'll leave it there for now.
Merry Christmas to all and see you on my return.
They happen to have a Dollarama store here in this town of 12k and guess what?
Right!
He is now the proud owner of 25 sheets of foam core [still $1.25 a sheet], a new glue gun and plenty of sticks.
When I get back I am going to ask more opinions on the 20" unit as that is as big as he can go. He's a handyman so building will be no problem.
Time to get back to the Christmas celebrations so I'll leave it there for now.
Merry Christmas to all and see you on my return.
Right on Cal! Your brother in law will get sucked up into this to eh? He he.... The 20 incher only needs 6 sheets of foam core by the way. I guess he can build 4 pairs! We are just about to have our big dinner so I better get back...
Merry X-mas!
He better order some drivers quick. I still recommend Vifa's for 20 inch model.
The 20 incher only needs 6 sheets of foam core by the way. I guess he can build 4 pairs! We are just about to have our big dinner so I better get back... Merry X-mas!
He better order some drivers quick. I still recommend Vifa's for 20 inch model.
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Ok, I added stuff to my AkAbak model: front baffle diffraction, horn mouths exiting at the sides, and a wall behind. Apart from the expected increase in bass due to the wall, the results weren't greatly different in the bass and lower mid range. I still think the best results will be obtained for a given driver by modelling a back-loaded horn in Hornresp or MJK's spreadsheets, then dividing the areas of each segment by 2 or 4 and laying out your own 2 or 4 spirals. There's nothing magic about the expansion profile of a Cornu law horn that makes it better then a classic conical or exponential profile.
One thing I haven't worked out fully is how to fit the designed horn into the "enclosure". The horn will have a resulting throat area, mouth area, length and internal volume. The internal volume will more or less match the volume of the enclosure (length x width x depth). The mouth area will more or less match the area of two of the enclosure sides (length x depth x 2), assuming a square faced enclosure. A deep enclosure will result in narrow "spirals", allowing a longer horn to fit in the volume. It's all a balancing act.
One thing I haven't worked out fully is how to fit the designed horn into the "enclosure". The horn will have a resulting throat area, mouth area, length and internal volume. The internal volume will more or less match the volume of the enclosure (length x width x depth). The mouth area will more or less match the area of two of the enclosure sides (length x depth x 2), assuming a square faced enclosure. A deep enclosure will result in narrow "spirals", allowing a longer horn to fit in the volume. It's all a balancing act.
Right on Cal! Your brother in law will get sucked up into this to eh? He he....
Merry X-mas!
He better order some drivers quick. I still recommend Vifa's for 20 inch model.
Sounds like a 7.1 system to me!!!
Don,
I am playing around with Akabak now. It took me a while to find an older computer that can run it. Can you explain why the driver chamber is modeled as segment 1 of the first horn? I am trying to see if the real Cornu's design makes a difference by having essentially 4 horns, each splitting into 2 more for 8. The horns have a divider so that the max cross sectional area is less than simply scaling the depth to account for more horns. This has to make a difference because smaller cross sections support smaller wavelengths. The real Cornu has a 7 cm deep horn with 2 layers for 14 cm total. However the driver chamber is 14 cm deep.
If you don't mind sharing the script wu Diffraction, wall, and edge emission, please post.
I think your idea to model a horn in HR or MJK first is good. Can't one use Akabak to model a straight horn to optimize then fold or roll up? What I am doing is simplifying the Cornu spiral to 3 segments of linear conical horns assuming they were unrolled.
Thanks,
Xrk971
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(Second attempt at replying, the malware warning popped up when I attempted to post the previous reply. Hopefully it won't duplicate.)
Convenience. I'll split it out as an enclosure for the next revision.
It won't make any difference at bass to mid-bass frequencies, provided you account for the thickness of the dividers.
I'll post an updated script shortly.
AkAbak assumes the horn is straight unless you include elements to model the effects of bends. It's generally unnecessary to model bends for "bass" horns (which the cornu is). The intent of the Cornu design, as with any back loaded horn, is to enhance the bass response and "lose" the high frequencies in the bends. You could go to the trouble of adding bends or otherwise modelling HF losses, but it's simpler to just ignore the HF part of the modelled response.
Convenience. I'll split it out as an enclosure for the next revision.
It won't make any difference at bass to mid-bass frequencies, provided you account for the thickness of the dividers.
I'll post an updated script shortly.
AkAbak assumes the horn is straight unless you include elements to model the effects of bends. It's generally unnecessary to model bends for "bass" horns (which the cornu is). The intent of the Cornu design, as with any back loaded horn, is to enhance the bass response and "lose" the high frequencies in the bends. You could go to the trouble of adding bends or otherwise modelling HF losses, but it's simpler to just ignore the HF part of the modelled response.
Don Hills,
Thanks for clarifying. So bass frequencies don't care if the channels are small? HR and MJK are also 1 dim models and bends are treated as expansion and contractions - I suppose they act as low pass filters but Akabak can do that too. I generally Ignore anything above 1000 Hz. I tried making 4 horns and it did not change the result either.
Thanks
Xrk971
Thanks for clarifying. So bass frequencies don't care if the channels are small? HR and MJK are also 1 dim models and bends are treated as expansion and contractions - I suppose they act as low pass filters but Akabak can do that too. I generally Ignore anything above 1000 Hz. I tried making 4 horns and it did not change the result either.
Thanks
Xrk971
hehe. I think he wants to do a 5.1 truth be told.
I seem to have a couple free minutes here before we start today's festivities so guess what I felt like doing?
Sometime in the new year I am going to get everything he needs gathered up and sent to him complete with a stencil so it will be easy sailing from that point on. He wants the 20" units so if he gets the same underlay \i did, each piece is good for 2 speakers.
We have already done some practice runs and he's comfortable with that.
Anyway, I hear a beer calling my name so I best go answer it.
Take care everyone.
xrk971,
The restrictions are: channel cross sectional area needs to be small enough that the dimensions are small compared with the wavelengths of interest, and large enough that the frictional losses can be ignored. For example, a simple duct will perform differently than the same duct filled with drinking straws.
I've tried including the expansion and contraction of bends in models. They don't significantly affect the bass performance, but as expected they do add resonances at higher frequencies.
The restrictions are: channel cross sectional area needs to be small enough that the dimensions are small compared with the wavelengths of interest, and large enough that the frictional losses can be ignored. For example, a simple duct will perform differently than the same duct filled with drinking straws.
I've tried including the expansion and contraction of bends in models. They don't significantly affect the bass performance, but as expected they do add resonances at higher frequencies.
Practice runs? You guys might as well build it together! It will go so much faster with your prior experience.
Have fun drinking beer by the Pacific.
If we had time, it would be built already. This is my wife's first trip back here in 15 years and these people are making up for lost time. 9 siblings in total so there's hardly a moment to spare. Today for example we went over to one of the brothers. He asked if we were hungry. We all said yes so he said follow me. We all jumped in to the cars and headed off to his restaurant. A popular restaurant that is actually closed at this time of year for the holidays [yes, this is standard practice here]. ANYWAY THIS IS A PLACE THAT SEAT ABOUT 100. hE, HIS WIFE AND A FEW OF THE SISTERS START RUNNING AROUND AND THE NEXT THING YOU KNOW WE HAVE ALL SORTS OF appies, tasters and then a huge bowl of Pho [beef noodle soup, Vietnamese style]. Did I mention my wife is Vietnamese?
THAT'S ONLY ONE OF THE FOOD STORIES, THERE'S MANY MORE BUT ANOTHER TIME..
Sorry about the caps, I'm too lazy to go back and correct it. I LOOK AT THE KEYS AS i TYPE. **** did it again. The caps lock on this PC laptop seem to be in the same spot as the shift key on my Mac. Oh well, as mentioned it's beer time so see ya later.
THAT'S ONLY ONE OF THE FOOD STORIES, THERE'S MANY MORE BUT ANOTHER TIME..
Sorry about the caps, I'm too lazy to go back and correct it. I LOOK AT THE KEYS AS i TYPE. **** did it again. The caps lock on this PC laptop seem to be in the same spot as the shift key on my Mac. Oh well, as mentioned it's beer time so see ya later.
Update-
OK, so I finished my first all foam core pair of 20" with Vifa drivers. Did some more experimenting with the stuffing. Over stuffed, under stuffed, learned the lesson in cheap fast foam. I was so moved by the result that I resuscitated my Tube Lab Simple, needed more power than the SE could deliver. I am listening to them now. Wow!
I had one day off before Christmas and spent a good part of it cutting baffles and routing. I don't really have a shop that I can make sawdust in, have to pull everything out to the driveway with sawhorses. Fortunately the weather was cooperative. I cut a pair of baffles in luan ply, 1/2' birch veneer ply and masonite. I promptly ruined the luan baffles with the router, I'm terrible around power tools... Impatient I guess. Successfully got the birch and masonite routed.
Finished the birch pair on Christmas morning and gave them to a friend in need (blown driver in his 2-ways). Hooked them up to an Elekit TU-879S amp I had built several years ago. Listened to lots of classic jazz, Miles Davis, Coltrane, Brubeck, Grant Green, etc. Just for fun I brought along my cheapo PE 12" sub and listened to the new Zeppelin Celebration Day and old Pixies. Yow! Yeah they can play rock music too.
Next week I plan to rob the drivers from the foam core pair and finish the masonite pair as a final (20"!) for myself. After that I'm not sure... might look at those 4 or 5" drivers.
I'll upload a photo soon.
happy holidays
OK, so I finished my first all foam core pair of 20" with Vifa drivers. Did some more experimenting with the stuffing. Over stuffed, under stuffed, learned the lesson in cheap fast foam. I was so moved by the result that I resuscitated my Tube Lab Simple, needed more power than the SE could deliver. I am listening to them now. Wow!
I had one day off before Christmas and spent a good part of it cutting baffles and routing. I don't really have a shop that I can make sawdust in, have to pull everything out to the driveway with sawhorses. Fortunately the weather was cooperative. I cut a pair of baffles in luan ply, 1/2' birch veneer ply and masonite. I promptly ruined the luan baffles with the router, I'm terrible around power tools... Impatient I guess. Successfully got the birch and masonite routed.
Finished the birch pair on Christmas morning and gave them to a friend in need (blown driver in his 2-ways). Hooked them up to an Elekit TU-879S amp I had built several years ago. Listened to lots of classic jazz, Miles Davis, Coltrane, Brubeck, Grant Green, etc. Just for fun I brought along my cheapo PE 12" sub and listened to the new Zeppelin Celebration Day and old Pixies. Yow! Yeah they can play rock music too.
Next week I plan to rob the drivers from the foam core pair and finish the masonite pair as a final (20"!) for myself. After that I'm not sure... might look at those 4 or 5" drivers.
I'll upload a photo soon.
happy holidays