The Metronome

[planet10]

Originally Posted by GrahamAshton

Your comments on the idea for a folded MET are confusing me. The Met is a dual taper design, front to back as well as side to side. If i'm not mistaken the mileva and demetri designs both have parallel front and back panels. The ideas I presented in my last post both tried to retain the dual taper concept.

This is true, but in most cases the deviation from a straight sided Voigt are small enuff to be ignored. One can take almost any set of Met numbers and build a straight Voigt. Mileva, came literally from the idea of folding a Met.

Does Martin Kings TL design tool cater for diverging and converging cross sectional area designs?

One of the sheets allows multiple straight line sections. One can get as close to a curve as one wishes by adding sections.

dave

[GrahamAshton]

Thanks for that Dave

[jwmbro]

Hi, I was wondering, how critical is the placement of the driver in the metronomes? is the total length of the chamber the important factor, or is the ratio at which the driver divides it equally important? I notice for most metronome designs, the driver seems to be placed at around 700-800mm off the ground.
Would it be possible to mount a driver around 1100mm off the ground? For example with the Fostex 168eS design - it would be tall enough to encompass a driver mounted so high, but would that ruin the design?

[Scottmoose]

I'm afraid the tap location (as in driver position from the throat) is important in supressing harmonic resonances etc.; if you're willing to compromise on that (& have some nulls in the response), then you can move it, but I wouldn't guarantee how successful it'd be.

[planet10]

Originally Posted by klankymen

I notice for most metronome designs, the driver seems to be placed at around 700-800mm off the ground.

If you look more closely it is usually 1/2. On a few it is closer to 1/3 (exact placement detailed by modeling in MJK)

dave

[spopepro]

Dave, Thanks for the drawings and data, helps a ton! I was intrigued by your EL-70 bipole drawing that provides a provision for side mounting in case of not having wall space. From the past 800 posts or so, I think I have figured out that 1) the fostex drivers will play better with my 15w PP EL84 amp 2) my loft with 15ft ceilings and a single room would benefit from a bipole design and 3) since the room is 12ft wide the speakers will need to sit too close to the wall for the rear facing speaker. Are my assumptions correct? Can I then take a driver like the FE126 and put the second speaker on the side (like in the EL70 drawing)? Would you then orient that speaker away or towards the primary listening position?

[mjneubrander]

I got the urge to build to use my old saws lately and decided after remodeling the bathroom cabinets I should take on making some speaker cabinets. At first I was thinking of using the fe166en and building angular spiral cabs they are small and seem that they would sound good. http://www3.ocn.ne.jp/~hanbei/eng-angular.html Helix-AG200BS. I could not find much info about anyone who have tried building these. Regardless I set out to make them. Then the miss of my life decided something tall and cool looking would be better. So I went looking for plans for a fe166en met and found they would probably fit in the cab for the 166e nicely. I accidentally clicked on the FE207e plans and had transferred all the measurements to the wood before I noticed. I had not ordered my drivers yet so I decided it was easier to just change that then erase. So here I go 2x fe207e are on their way and I will start cutting wood this weekend. Wish me luck Im excited about my first DIY sound project. Included for your viewing pleasure... very low quality cell phone pics. Showing my use of plywood as a straight edge and my lovely 2 pieces of birch 5 ply 4x8s. Flicker shots for full quality. Advice and comments welcome.

[planet10]

Fe207 is probably a better fit with a Met, but you may find that a bit of help on the top is needed.

dave

[mjneubrander]

Would a pair of small mets that fit on top of the 207e maybe a 1in driver be possible, design wise, to fill out the high end. Think of it as a double decker met. That way I could still match the style. Or would that distort too badly or any other holes you can poke in the crazy idea.

[planet10]

It would be elegant, but you want the helper tweeter as close as possible to the 207. The usual candidates are the Fostex FT17, FT96 or a set of the Foster horns out of the Radio Shack add on pods if you can find some (i have a stash)

With some aforethot (in particular placement of any holey driver braces), these can be retrofitted if need is determined.
dave