"Piscis" 3-Way Project

[ColoradoTom]

I figured I'd start a new thread because some of the others are starting to get a little "long in the tooth"

Since the mid and high drivers are in flux I'm starting on the bass units and then will add the "head" unit in the future.

I've modeled a vented cabinet for the two Aura 12's in UniBox. The cabinet size is 145 liters (5 cubic feet) with a 10.15 cm (4 inch) port that is 43.7 cm (17.2 inches) long.

Outside dimensions are roughly 44 inches tall, 17 inches wide, and 27 inches deep. These dimensions allow one to get four side panels of the actual cabinet for glue up out of a standard 4 x 8 foot sheet of MDF or plywood. I've been doing layout of the side panels on a 2 x 4 foot sheet of MFD so that I could be sure my calculations were correct. The front baffle will be 6 inches thick and faceted in "Avalon" style. The whole cabinet is slanted back at a 10 degree angle and is internally braced with four shelf braces horizontally as well as vertical braces between each shelf. All braces are one inch thick and all walls are two inches thick. I will try to be more detailed in construction description and pictures as I progress.

I'm sorry I'm not a CAD person - I normally go from a sketch to a full sized detailed diagram when I work because I like to have a full size representation to check my progress. I will post a picture of the cabinet/brace layout (excluding the front baffle) later today or tomorrow.

I've already purchased a stash of Santos Rosewood veneer for this project so these will match my prior "Avalon" effort!!

I should have the cabinets finished and ready for testing in two weeks.......... just kidding!! I'm hoping that I'll have something ready for listening by the end of August. I'll most likely start glue-up this weekend.

Tom

[JamesK]

Fun! I will follow your build closely.

[PoorboyMike]

I have no interest in following this project.


No offense Tom, but I don't like the fact that you're projects make mine look like they were made in 3rd grade shop. ;x(


Obviously I'm joking about the not interested part. Looking forward to the pics. 8)

[chasw98]

The front baffle will be 6 inches thick and faceted in "Avalon" style.

That sounds like Doc Brown in the gigawatts expression, only in wood. 6 inches thick! I guess you are making it that thick so that the facets will work correctly and it sure does make for a very solid front plate to mount woofers on. My question is "Why are you going to make it vented?". I am just curious. I have been following the 'long in the tooth' threads in anticipation of making this speaker since Jon talked about an Avalon clone of some sort. I will probably start building this along with you once you publish some facet tricks and jigs. Did you look at modeling these in a sealed cabinet?

Chuck

[ColoradoTom]

That sounds like Doc Brown in the gigawatts expression, only in wood. 6 inches thick! I guess you are making it that thick so that the facets will work correctly and it sure does make for a very solid front plate to mount woofers on. My question is "Why are you going to make it vented?". I am just curious. I have been following the 'long in the tooth' threads in anticipation of making this speaker since Jon talked about an Avalon clone of some sort. I will probably start building this along with you once you publish some facet tricks and jigs. Did you look at modeling these in a sealed cabinet?

Chuck

I can get about 6dB increase in the lower 20's with a vented design. With the vented design Marty won't blow the speaker cones across the listening room!

Should have some design pictures later this morning/afternoon

Tom

[ColoradoTom]

I have no interest in following this project.


No offense Tom, but I don't like the fact that you're projects make mine look like they were made in 3rd grade shop. ;x(


Obviously I'm joking about the not interested part. Looking forward to the pics. 8)

I'm sure I'll screw-up some things along the way to keep you happy/interested.

Tom

[JonMarsh]

Outside dimensions are roughly 44 inches tall, 17 inches wide, and 27 inches deep. These dimensions allow one to get four side panels of the actual cabinet for glue up out of a standard 4 x 8 foot sheet of MDF or plywood. I've been doing layout of the side panels on a 2 x 4 foot sheet of MFD so that I could be sure my calculations were correct. The front baffle will be 6 inches thick and faceted in "Avalon" style. The whole cabinet is slanted back at a 10 degree angle and is internally braced with four shelf braces horizontally as well as vertical braces between each shelf. All braces are one inch thick and all walls are two inches thick. I will try to be more detailed in construction description and pictures as I progress.

I'm sorry I'm not a CAD person - I normally go from a sketch to a full sized detailed diagram when I work because I like to have a full size representation to check my progress. I will post a picture of the cabinet/brace layout (excluding the front baffle) later today or tomorrow.

I've already purchased a stash of Santos Rosewood veneer for this project so these will match my prior "Avalon" effort!!

I should have the cabinets finished and ready for testing in two weeks.......... just kidding!! I'm hoping that I'll have something ready for listening by the end of August. I'll most likely start glue-up this weekend.

Tom

I'll be interested to see your sketches- being a crossover meister and a wood cutting hack, I've been expending some extra diligence to come up with a nice design with rabbeted joints and some additional woodworking "tricks".

Yikes! 6" front panel and 2" walls - that's going to be one scary heavy set of cabinets! :E :T The M8ta's were a bit scary for me, post back surgery, and though I hope to improve on them a bit, I'm not planning an all out assault like yours....

Mine will be more a mini-system, you know, like those little bookshelf jobbers with CD player, iPod connectors, and nice compact detached speakers... :rofl:

But then, I may be able to pick them up unaided. :W

[ColoradoTom]

I'll be interested to see your sketches- being a crossover meister and a wood cutting hack, I've been expending some extra diligence to come up with a nice design with rabbeted joints and some additional woodworking "tricks".

Yikes! 6" front panel and 2" walls - that's going to be one scary heavy set of cabinets! :E :T The M8ta's were a bit scary for me, post back surgery, and though I hope to improve on them a bit, I'm not planning an all out assault like yours....

Woodworking hack my ass..... you seem to be able to do just fine!

Attached is the layout from a side view on a 2' x 4' sheet of MDF. This represents only the cabinet w/o the front baffle attached. The baffle would extend an additional 6" to the left in the photo. The width shown from the back (on the right side) to the front (on the left side) is 21". Height is 44". You can also see the layout for the bracing and the vent.

The top, back, and bottom will fit into a 1/4" rabbet cut into the side panel and additionally will have loose tenons securing the joints (gotta justify that Festool Domino!). Internal braces will be attached to the sides and to each other with loose tenons. The front baffle wiil be attached with loose tenons as well.

Second photo shows some unfinished pieces of the Santos Rosewood that will be used for the veneering of the finished speakers.

Please let me know if you notice anything I've missed :E .............

Tom

[TacoD]

A length of 45 cm seems a bit long for a port. If you make the port in the underside of the cabinet don't forget the extra loading you get from the floor.

[ColoradoTom]

A length of 45 cm seems a bit long for a port. If you make the port in the underside of the cabinet don't forget the extra loading you get from the floor.

The length was calculated from UniBox.... is there a way to incorporate the floor loading??

Thanks TacoD

Tom

[JonMarsh]

Yeah, the floor is a boundary load, but that's part of why the anechoic response is tuned as described in Unibox. With Fb in the range of -6 to -8 dB, the in room response is tight and deep. Obviously this is tuned below resonance, like most of my other designs.

In my 76 liter single twelve design I wound up with a 49 cm port, for an Fb of 18 Hz. Since construction and testing of the first bass bin is the next task, the answers to how that works should be available soon.

Tom, are those perpendicular light pencil outlines where you plan your internal braces? (vertical and horizontal).

~Jon

[Hank]

Rabbets, tenons, oh my! Next they'll be using wood screws. You won't need spikes, you'll need casters to be able to move those bad boys.

Very nice looking veneer. Rosewood is still my favorite. I look forward to seeing construction pics.

[JonMarsh]

Pisces Vegrandis

OK, figured out the name in Latin. That is, for my version. Although "Pisces Tantillus" would be appropriate, too.

You, Tom, will have to go with "Pisces Maximus", or "Pisces Magnus", or "Pisces Maior".

Take your pick. :W :B

Yeah, Hank, I'm going to have to up my standards now that we have some real woodworkers on the board. :rofl: Won't be able to get away with those but joints anymore, or I'll be the "butt" of a lot of jokes. :B

[ColoradoTom]

Tom, are those perpendicular light pencil outlines where you plan your internal braces? (vertical and horizontal).

~Jon

Yup.... they are in pencil so that I can move them around.... this is basically caveman CAD!!!

I assume that the braces should not be layed out in a symetrical pattern to remove the possibility of any given panel having the same resonance... is this correct and does it make a big difference???

This thing is starting to scare me a bit... it looks like it could weight in the 200-250 lb range. I guess I better start working out on my TotalGym!! :lol:

Tom

[ColoradoTom]

OK, figured out the name in Latin. That is, for my version. Although "Pisces Tantillus" would be appropriate, too.

You, Tom, will have to go with "Pisces Maximus", or "Pisces Magnus", or "Pisces Maior".

Take your pick. :W :B

Yeah, Hank, I'm going to have to up my standards now that we have some real woodworkers on the board. :rofl: Won't be able to get away with those but joints anymore, or I'll be the "butt" of a lot of jokes. :B

What..... no Pisces Giganteus option!!! :rofl:

[ColoradoTom]

You won't need spikes, you'll need casters to be able to move those bad boys.

And a hydrolic lift to get it on and off my bench............. :E

[---k---]

http://www.exfactory.com/equipment.aspx?catId=FL

:B

[JonMarsh]

Yup.... they are in pencil so that I can move them around.... this is basically caveman CAD!!!

I assume that the braces should not be layed out in a symetrical pattern to remove the possibility of any given panel having the same resonance... is this correct and does it make a big difference???

This thing is starting to scare me a bit... it looks like it could weight in the 200-250 lb range. I guess I better start working out on my TotalGym!! :lol:

Tom

The ideal thing would be golden mean ratios for the unsupported area dimensions... golden mean ratios are the solutions to all problems, aren't they? :B

[oxcartdriver]

Grab plenty of pictures. And document the construction. I'm going to wait for the complete design to be completed prior to starting construction, I'm such a sheep.

Hat's off to you for starting early and blazing the trail on the bleeding edge. Let me be the first to say Thank You, in advance.

[ColoradoTom]

The ideal thing would be golden mean ratios for the unsupported area dimensions... golden mean ratios are the solutions to all problems, aren't they? :B

Re-worked the bracing using some modified golden mean numbers (4.5, 7.5, and 12) and have a spacing that creates no two areas on the panel of the same size or area (hope that makes sense). I'll post more detail plans/pictures if someone wants them. I've noticed that there are several designs that incorporate a brace the engages the baskets behind the drivers - I assume that this is something I should do as well.

Later..............

Tom

[ColoradoTom]

Grab plenty of pictures. And document the construction. I'm going to wait for the complete design to be completed prior to starting construction, I'm such a sheep.

Hat's off to you for starting early and blazing the trail on the bleeding edge. Let me be the first to say Thank You, in advance.

Will do................... off to play some bass 8) .

Tom

[TacoD]

Re-worked the bracing using some modified golden mean numbers (4.5, 7.5, and 12) and have a spacing that creates no two areas on the panel of the same size or area (hope that makes sense). I'll post more detail plans/pictures if someone wants them. I've noticed that there are several designs that incorporate a brace the engages the baskets behind the drivers - I assume that this is something I should do as well.

Later..............

Tom

The support of the woofer basket is a very good idea, this helps to reduce the vibrations at the source.

[chasw98]

I'll post more detail plans/pictures if someone wants them.

YES! We want them! Thanks for doing this Tom.

Chuck

[ColoradoTom]

Problems in ColoradoTom land.....

Ok....

So I wanted to do some work on my M8tas recently (increase the size of the facets a bit and complete some finish work) before I got too involved with this project. While I was lifting them from my basement to my garage workshop I felt like I pulled a muscle in my stomach. 8O No big deal - we're all getting older I thought. Then, while serving in a tennis match last week I started to feel a sharp pain and felt a lump near my belly button. :E Well it looks like I have an umbilical hernia. The doctor wanted to take a watchful waiting position until I informed him that I was about to embark on a "gut busting" speaker project. :rofl: Looks like my work on this project will have to wait until I see a specialist or until after the operation to fix it!! One way or the other this will be on hold for the next couple of months. :cry:

This really sucks!!!!!!!!!

Tom

[JonMarsh]

Ok....

So I wanted to do some work on my M8tas recently (increase the size of the facets a bit and complete some finish work) before I got too involved with this project. While I was lifting them from my basement to my garage workshop I felt like I pulled a muscle in my stomach. 8O No big deal - we're all getting older I thought. Then, while serving in a tennis match last week I started to feel a sharp pain and felt a lump near my belly button. :E Well it looks like I have an umbilical hernia. The doctor wanted to take a watchful waiting position until I informed him that I was about to embark on a "gut busting" speaker project. :rofl: Looks like my work on this project will have to wait until I see a specialist or until after the operation to fix it!! One way or the other this will be on hold for the next couple of months. :cry:

This really sucks!!!!!!!!!


Tom

No kidding! Sounds like you're stealing from my playbook- sproinged my back two weeks ago(same region as I had surgery for in 2003), just getting back to 80% of normal the end of last week. At least I'm working on small speakers at the moment, other than gluing up the Test Article 2 for the Isiris dipole speaker project.

Sorry to hear about your difficulty- may give me an opportunity to "pull ahead" on the "Pices Jr" depending on how my 3 week break the last week of August and first two weeks of September go. Isiris development is the big push then, but finishing a drawing plan and first cabinet for Pisces Jr. is number 2. Still expecting to go with the C30N on the first pass, need to do distortion measurements on them and TD120tdc first.

[chasw98]

Tom:
What a shame. Don't you hate it when that happens. Look at the bright side. The weather will be cooler when you get back to the project, maybe real cool where you live!

Chuck

[TacoD]

The length was calculated from UniBox.... is there a way to incorporate the floor loading??

Thanks TacoD

Tom

If your cabinet has a plinth which also act as a "tunnel" like the ones Avalons makes this distance also increases the port length.

In my own design with Eton 11" and std 38mm feet, my calculated port was still to long. I already tuned very low (25 Hz or so) but I ended up with 18 Hz. In my application the bass became to "lean".

Also my experience is that if you calculate a port for a certain length say 25 cm in real life the tuning is lower than calculated. See also the article of Troels http://www.troelsgravesen.dk/vent_tuning.htm

[ColoradoTom]

No kidding! Sounds like you're stealing from my playbook- sproinged my back two weeks ago(same region as I had surgery for in 2003), just getting back to 80% of normal the end of last week. At least I'm working on small speakers at the moment, other than gluing up the Test Article 2 for the Isiris dipole speaker project.

Sorry to hear about your difficulty- may give me an opportunity to "pull ahead" on the "Pices Jr" depending on how my 3 week break the last week of August and first two weeks of September go. Isiris development is the big push then, but finishing a drawing plan and first cabinet for Pisces Jr. is number 2. Still expecting to go with the C30N on the first pass, need to do distortion measurements on them and TD120tdc first.

I don't know.... maybe this will work out just fine. I've been spending the last couple of weeks getting the Sound Lab M-1's back into the system and I might focus on working on some bass traps and other acoustical treatment options as the working materials are significantly lighter than 6 inch thick MDF/BB panels . Depending on the type of operation I may be able to do heavy lifting as early as 6 weeks afterwards but scheduling probably won't happen until October/November.

It may give me a chance to get the Sound Lab M-1's tuned up by the time the Rocky Mountain Audio Fest is going on. I've changed the positioning in my audio room and I'm liking the results so far. Are you still planning on a visit?

[JonMarsh]

Yes, definitely planning to be there- will probably book my air travel right after I get back from Singapore.

We hope to have a finished set of Modula NeoD CC with the new crossover, and a pair of Isiris to demo for anyone that drops by- I think Thomas will setup an open house one afternoon. I may ship out some stuff temporarily for the demos, like my SACD player and integrated amp. Just to annoy folks I'll bring all my good cables. :W

[ThomasW]

Having a hernia is no laughing matter.

That said, Weird Al's video about the subject is funny...

https://web.archive.org/web/20070717042146/http://www.jibjab.com/view/47094

[seeker]

Depending on the type of operation I may be able to do heavy lifting as early as 6 weeks afterwards but scheduling probably won't happen until October/November.

Best wishes for your health. BTW, if you need help moving big, beautiful speakers, just let me know . I'm not far away and have a little brother just outside your town.

[Jed]

Tom, I say go Dipole. Much lighter! And you have the room for one. That might be what I do with my NS10s. Just got my Music/Design software to model it.

Jed