noob building the fonkens

[planet10]

Originally Posted by murphythecat8

If I'm not mistaken, the back panel wide is 190.2, and the bottom is 229.7. How can both arrive flush? is doesnt make sense, is it when the sides are done?!

Outside width on the 15mm drawing is 229.7mm, there is no explicit dimension for the width of a back panel inset between the sides, but (given your material is 15mm) the back needs to be 199.7mm.

dave

PS: I did find some errors in the front view of the 15mm plans. None relevant to the issue at hand.

[murphythecat8]

Originally Posted by planet10

Outside width on the 15mm drawing is 229.7mm, there is no explicit dimension for the width of a back panel inset between the sides, but (given your material is 15mm) the back needs to be 199.7mm.

dave

PS: I did find some errors in the front view of the 15mm plans. None relevant to the issue at hand.

perfect, thanks!

[murphythecat8]

Can someone point me what exactly butt joint I need to do for this project, theres different butt joint, so which one is the simplest and require as less as possible cutting: I'm not good with a table saw.

also, when Chris you say :"glue the damping pads to the inside surface before attaching the tops and bottoms.". Does it mean that I need to put isolation between the spacers (between the inner and outer sides) .
Also chris, I dont understand the whole sentence:"Just be careful to carefully measure extent of chamfer, and locate any such fasteners to not be in the tool path it's cut after assembly. I prefer this method as it's very quick and I have access to large enough tools for the task. Clamp a sacrificial scrap to trailing edge the enclosure to prevent chipping at tail end of cut."

thank you guys

[murphythecat8]

Originally Posted by chrisb

A few words from the Fonken-ator:


I've built dozens of pairs of this design over the past 5 yrs or so, and for various reasons ( experimenting with material thickness, driver models, and refining of port & internal bracing details ), several of them have finished at slightly different dimensions than the stock drawings that I assume you're working from.


I don't have a set of said drawings in front of me, but do have about 4 pairs of the Fostex & Mark Audio versions of this design in my room, as well as a tape measure.

Let's assume for convenience sake that you're using 15mm plywood for panels and 3/8" (9.5mm) MDF for the spacers between inner and outer side walls - which are the materials used for the pair of FE127E Fonkens I have in at my desk, and from which the following measurements are taken. (We'll ignore allowance for .5mm thick veneer on all sides)

The finished outside dimensions are 227mmW x 354mmH x 302mmD (9"x 13 15/16" x 11 7/8") . These are constructed using butt joints, with the top and bottoms overlaying all panels, and assembled with the front panel full width - the chamfers are cut after all except the back panel are assembled.



Top / bottom = 227mmW X 302mmD
Outside wall panels = 324mmH x 287mm W
Inner wall panels = 324mmH x 242mmW
Brace = 324mmH x 272mmW
Front panel = 324mmH 227mmW
Back panel= 324mmH x 197mmW

Width of Port spacers can adjusted for aesthetic variation of location of port slots, but using 9.5mm thick material the 3 slots per side need to be 75mmH. There will be 4 spacers per side - 2 between the slots, and one at each end. Cut these parts to 272mm long to provide additional glue surface area and bracing for the fully inset back panel.

If you're overlaying the back panel, the width of outside panels will need to be reduced to 272mm and the back panel increased to 227mm wide. This might be make assembly a little bit easier, but if all parts are precisely cut, insetting the back is not the most complicated part of the fabrication, and provides a more well braced joint.

Thanks chris, but theres a couple of nothing I didndt understood.


So the ports(spacers) need to be 272mm long and what width?

So the ports need to "touch" the back panel when I'll install the back panel. And when I put the back panel, I will glue each spacers to the back panel. Am I right? 1-so the spacer will reach the back panel?


2-I should start by taking my outer-side, glue the spacers (ports) on it. Then glue the isolation (damping) in between the ports.

3- glue the inner-side to the spacers and then glue isolation on the inner side.

4-then glue the sides to the bottom panel?

5-then the baffle? Also I have a question about the baffles. I Imagine that I install them right at the end of the bottom side, just want to make sure.

6- then put isolation everwhere I can, then install the the baffle, and the obvious suite...

Please anyone tell me if thats about it. Also, really need to know what butt joints,

[murphythecat8]

Chris, the thing is, I dont have a table saw, so it's at the wood place that they will cut my wood. can you confirm that if I follow the dimension you told me, it will be fine?: Top / bottom = 227mmW X 302mmD
Outside wall panels = 324mmH x 287mm W
Inner wall panels = 324mmH x 242mmW
Brace = 324mmH x 272mmW
Front panel = 324mmH 227mmW
Back panel= 324mmH x 197mmW

Width of Port spacers can adjusted for aesthetic variation of location of port slots, but using 9.5mm thick material the 3 slots per side need to be 75mmH. There will be 4 spacers per side - 2 between the slots, and one at each end. Cut these parts to 272mm long to provide additional glue surface area and bracing for the fully inset back panel.

Thanks

[chrisb]

First, let's start over with confirmation of plan-set / dimensions etc. I trust that you haven't cut material yet.

As I mentioned earlier, Dave has made countless revisions to many different enclosure designs over the past 10 yrs, but doesn't actually fabricate them.

I generally redraw in my own CAD software for cut planning layout, allowing for further minor revisions, and easy export of to CADCAM for CNC routing of driver cutouts, etc. Further, it might not make sense, but I also find the act of drawing the enclosure in 2D helps in wrapping my head around fabrication and assembly sequence for some of the more elaborate designs, for which I think the "prime" Fonken style enclosures qualify.

In any case, the result is that I'm often working from my own drawings rather than Dave's, and in the case of something like the FE127 Fonken, mine may well differ in some dimensions. As there are a lot of individual pieces (17, I seem to remember?) per cabinet that need to nest together in a quite specific manner this could certainly confuse things.

I'll review the plans that you're probably working from and confirm / correct dimensions. Then hopefully the confusion can be cleared up.

Also keep in mind that after building many dozens of pairs of this cabinet format for several different drivers during the past 7yrs or so, I have fallen into my own pattern of fabrication steps - mostly in attempts to streamline working time. There are certainly other ways.

[chrisb]

murphy:

Attached is my current "as built" drawing for the enclosure in question - Fonken enclosure for FE127E.

As noted in earlier posts, these will certainly vary from Dave's "official" drawings, which include errors of measurements and artifacts from revisions to material thickness as well as conversion between imperial and metric.

Ignore all previously posted dimensions, as they included errors for the above reasons.

Note the following:

1) Drawn for actual metric material thickness of Baltic Birch plywood at 15 & 18 (front panel) , with dimensions for optional 15mm front panel shown in blue . Built as drawn, the box is quite well braced and fairly rigid, and if the driver is not rebated for flush mounting, 15mm is quite adequate. Unlike round flanges of Mark Audio drivers, the Fostex pin-cushion frame shape is rather tricky to free-hand with router, and a lot of builders surface mount them. I have the advantage of access to a CNC router.

However, whichever thickness of material and mounting is used for the FE127E, the bevel on inside of driver cut-out is important.

2) Dimensions have been "rationalized" or rounded up to nearest mm - direction conversion from imperial to metric can result in .1 or even .01 tolerance on mm - rather hard to cut except on a production CNC beam saw or router.

3) Red hashed areas shows the extent of port divider / panel spacers - note that they extend full length of the cabinet to provide additional bracing when the back panel is fully inset. The result of #2 above is that these strips want to be 26.25mm or 1.033" wide. What I do is cut 3 spacers 75mm wide ( the finished "height" of ports when the cabinet is upright), and adjust the equal 4 panel divider strips to fit flush at each end of the outer wall panel.

That's probably enough for now. For any further questions regarding fabrication, etc., (particularly regarding the driver brace) PM me.

[murphythecat8]

thanks a LOT chris!

[chrisb]

Jason;

check your PMs - this is not a build that you want to rush - it took me a few tries to get the sequence reasonably OK

[murphythecat8]

thank you everyone, especially chris.

My Fonkens are build!

I did huge noob errors, but have been able to cover them up. I used the wrong dimension, so I cut both time my wood, but all in all, they are done, and already sounds pretty good.

I have a bit of experience with vintage speakers, and the fonkens, not yet burned in, sounds pretty wonderful. Already noticing this midrange. The midrange is wonderful.

I'm happy! and proud! Thanks everyone, and happy listening.

Thanks