Build Thread - HiVi F8 / Seas 27TDFC

[robert]

I have been fooling with this for a long time in simulation, and started box construction last week. See Links for pics.

Cabinet is 3/4" MDF with 1"x1" hardwood corner blocks and 1.25" dowels to brace the sides and connect the front baffle to rear. I like dowels better than shelf braces because they are easy, and you can really crank them tight with Gorilla Glue and 3" deck screws. Also, the panels are large and a bit floppy, so they need it. The tweeter is rebated, while the F8, having a huge beauty ring with 12 screws!!! doesn't require it.

Volume with bracing is app. 2 cubic feet, cabinet will be tuned to app. 32Hz, for an F3 of app. 31Hz. Bit of a shelved alignment. Outside dimensions are 11.75" x 25" x 17.5" and were chosen to max out use on 2' x 4' sheets of MDF. 3" Flared precision port in front, due to relatively low power handling at FB before Xmax is reached.

Measured T/S Spec's for F8 (average of two and they were quite close:

FS: 37.5Hz SD: 220cm2
VAS: 41.3L BL: 10.1
QES: 0.43 RE: 6.35 Ohms
QMS: 6.95
QTS: 0.4
LE: 0.77mH
XMAX: 5mm
SPL: 87.8dB


The deep bass response is one of the reasons I chose the HiVi (besides the sale a while back ). It is also relatively smooth out to 3Khz. There are a few 8's out there capable of running in a 2-way without extreme crossover implementation, notably the Seas that Brian used, the Usher 8137A, and (probably the best), the two Eton 8" models, though 225.00 is steep.

The Seas 27TDFC's went in because of their success in low XO point designs and their availability (had a pair in the closet). Easy to use doesn't even begin to describe them! The HiVi's took a little longer, but once I figured out that I only needed 2 components, they snapped in.

Crossover is an LR4 at app. 1600Hz; in the model I got there with 5 components. With real-world in-box measurements, this will likely change a bit, so I'll post it when it is done. I am hoping to stay with the simple LR2 electrical for an LR4 acoustic, though!

Stuffing will be 1.25" Sonic Barrier, with Acousta-Stuf in top and bottom and a bit on back for a little node suppression.

The cabs are large and will require stands, and may also be tipped back a bit to bring things into better alignment (the F8 is a fairly deep driver). I was taking my time and enjoying things a bit but have been notified of more excessive travel so I'll have to haul a** for Iowa.

http://i123.photobucket.com/albums/o...leComplete.jpg

http://i123.photobucket.com/albums/o...eBlockedin.jpg

Cheers / Robert

[millers]

Re: Build Thread - HiVi F8 / Seas 27TDFC

how do you post a new thread?

[Steve Henry]

Re: Build Thread - HiVi F8 / Seas 27TDFC

Click the blue "New Thread" box on the first page of Tech Talk.

[brianpowers27]

Re: Build Thread - HiVi F8 / Seas 27TDFC

Can't wait to hear them Robert. I have to say that my similar 8" 2 way is very satisfying , when run full range. Of course it isn't loud enough to rovk out a large venue but it is very nice in a normal size room. The system also crosses well to a sub at 40hz.

[Mark65]

Re: Build Thread - HiVi F8 / Seas 27TDFC

Good looking so far, Robert, keep it coming!

Mark

[Ludo]

Re: Build Thread - HiVi F8 / Seas 27TDFC

Looking good.

The F8 is the yellow kevlar one?
I really like the sound of its baby cousin the D5G.

I'd like to see how you do the bracing with the dowels if you get time to snap another photo at some point.

Thanks,
Louis

[robert]

Re: Build Thread - HiVi F8 / Seas 27TDFC

Continued the build today - beautiful weather in the low 70's

Attached are pics of the first cabinet going together (4 sides, left top and bottom off). I usually attach sides and back to bottom, add top and then baffle, but this was strangely easy with the mambo corner blocks.

First photo: the mighty 3" deck screw. After the panels and blocks are gorilla'd, I fasten the panels. Then - SCREEK!!! in goes the deck screw into the corner blocks - visually noticeable tightening of the joints.

http://i123.photobucket.com/albums/o...rnerblocks.jpg

Next: side-side dowel installation and fitting. Note: :eek: do NOT tighten them without the front baffle in place! I cut these a little short and had to shim them a bit - no worries.

http://i123.photobucket.com/albums/o...Sidedowels.jpg

Dowel installation on front panel (make it a 1/16" to 1/32" short). I use 3" deck screws on all of the dowel braces.

http://i123.photobucket.com/albums/o...hdeckscrew.jpg

Dowels installed in cabinet (no top-bottom as they are the smallest panels, things were getting crowded, and they'll be loaded with 1.25 sonic barrier):

http://i123.photobucket.com/albums/o...13DowelsIn.jpg

And finally, 'cause I couldn't help myself, I had to see what the shape of the cabinet did with the drivers and port installed. It came out pretty good form-wise and I don't think it looks huge, even at 2cf. They will be 1.5" taller with top and bottom pieces on and beautiful, I think in walnut. I'll also paint the port flat black like I did on the ZRT's - it looks more professional and matches the driver frames.

http://i123.photobucket.com/albums/o...208/17Form.jpg

The F Series has way different motor and structure than the D's. They are more standard-style, while the D has the Dynaudio - style. I would have LOVED to use the D8-G due to stunning sealed bass but the driver is definitely designed to be the bottom of a 3-way.

The D'll beat the F on bass, but the F8 has the HF extension, reasonable capability ported, and cheapness for this design. I didn't want to exceed the tweeter price and these are squarely aimed at budget in Iowa.

Next cab tomorrow...note my glue sloppiness compared to LunchMoney :p

I also may flatter LunchMoney for his stand design!!!

Cheers / Robert

[Operandi]

Re: Build Thread - HiVi F8 / Seas 27TDFC

Looks great. I've been thinking about a 8" two-way tower for a while now, mainly brianpower's Northseas but this looks like a great option too.

[BasTek]

Re: Build Thread - HiVi F8 / Seas 27TDFC

It looks great. I was thinking about building the Seas Trym 8" 2way, but this could be an economical alternative.

[robert]

Re: Build Thread - HiVi F8 / Seas 27TDFC

All: remember that this is:

a.) One of my first totally unassisted designs :p
b.) built in sim only so I'll have to get cabs together and measure/load into SE to validate the XO.
c.) Get them built, listen lots in-rooms, and tweak a bit.
c.) It's gonna be a while - work is screaming again and this weekend is the first I've had in a long time to concentrate on speax. At least weather is cooperating

I'd also say that if possible you should listen to a design prior to build to ensure that you like it, especially one that is going over 100 bucks. I am going to try to get one cab together so I can take near/far field measurements and load into SE to validate the XO but may not get there today. I am up early though, and it is a good sign!


Cheers / Robert

[kevinr]

Re: Build Thread - HiVi F8 / Seas 27TDFC

Thanks for sharing , I'm planning on building a box myself after buying a router and it's very helpful to see people who post pictures of the builds in progress .
Let us know how things turn out .

[Operandi]

Re: Build Thread - HiVi F8 / Seas 27TDFC

All: remember that this is:

a.) One of my first totally unassisted designs :p
b.) built in sim only so I'll have to get cabs together and measure/load into SE to validate the XO.
c.) Get them built, listen lots in-rooms, and tweak a bit.
c.) It's gonna be a while - work is screaming again and this weekend is the first I've had in a long time to concentrate on speax. At least weather is cooperating

Makes sense. I'll be following the progress though ;).

Do you plan to take these to any events?

[turn2]

Re: Build Thread - HiVi F8 / Seas 27TDFC

Excellent Robert! Your boxes look remarkably similar to some in progress in my basement. The difference would be I have a pair of boxes off to the side that say "Usher" instead of "Seas". I'm inspired to find some sanding time.

[robert]

Re: Build Thread - HiVi F8 / Seas 27TDFC

I really want to get them finished by Iowa, but one of our field reps quit and I am in VA cleaning up several projects and getting them back on track. We normally start paperwork at T-180 days and I had 48 hours and shipyards to tromp, OMG! Another hotel room, sigh.

What you saw is about as far as I got before work called, am hoping to get more done on some of my upcoming home breaks from here. The time/work situation isn't looking too good at this point, but things could change. I may not even make Iowa, but hopefully the time will appear to finish.

Cheers / Robert

[robert]

Re: Build Thread - HiVi F8 / Seas 27TDFC

One Down, Four To Go; Another Town, Another Mess Fixed! :p

http://i123.photobucket.com/albums/o...oxtogether.jpg

See attached photo - got one cab put together and am using 1.5 Sonic Barrier for interior damping. Will also round corners and acousta-stuf prior to measurement. I am jamming to get this one together and set up to get some "in-box" measurements to import into SE. Then the real work starts, as the initial model was made using MFR graphs. For the Seas, no worries, for the HI-VI, I am hoping for "remarkable similarity"

I got a few days home but have to go back out Sept. 8. Gonna be close and I would love to stay home and finish, but serious ducats to make in VA.

Cheers / Robert