Help with port size on Metronome 167E

[jmillerdoc]

Hello,
I have recently decided (for the moment) against the Fonken enclosure for the 167E mainly because the complexity of the build. I think I am going to go with the Metronome. I found this example enclosure: http://homepage.mac.com/tlinespeaker...67-1v0-map.pdf but it doesn't show a port. The table shows a 3" diameter by 2" long port but the entire dimensions seem to be a little different on the table when compared to the example plans above.

I guess I have two questions.....first is this example above appropriate for the 167E and second what is the port size for these particular plans?

Thanks,
Jeff

[planet10]

Jeff,

Syncronystically, Scott & i were talking about the FE167 Met last night.

There is a slightly smaller Met buried somewhere in my emails, it is better suited than the FE207 Met re-ported for the FE167. A smaller monolith for the FE167 will follow from that.

The sketch you are seeing probably has both FE207 & FE167 ports in it.

dave

[jmillerdoc]

Great! I would love to get the dimensions if you can dig them up. I really appreciate the Fonken plans you gave me too. I am going to save those for a later day though. I want to get a pair up and running for a 2A3 amp I just built and the Fonkens will take too much time, more than I am interested in investing at the moment.

I am in the process of finishing a mini-Fonken type of enclosure for those 10F3's I was talking about on the other thread. Here it is: Humble Homemade Hifi
I don't know what to expect from these but they were fairly easy to construct and I had just enough Birch 3/4" plywood to make a pair. Should have them together by noon tomorrow.

Next is the Metronomes. I would like to get started on them tomorrow since I have the day off. Please let me know if you find that email, I would really appreciate it!

Does the Metronome with the 167E require any sort of inline filter? I saw the Zoble and BSC circuits at Furgal-horn. I was planning on using them unless somebody convinces me to do something else.

Anyways, thanks for your help.
Jeff

[jmillerdoc]

I was hunting around and found this: http://www.quarter-wave.com/General/...BIB_Design.pdf

It seems even easier to build than the metronome. Which of these (BIB or Metronome) would you personally recommend?

It appears the BIB just requires a simple rectangular box with the opening on the top. I am wondering on what type of material should be used for the BIB, seems the length is a big factor here, 136" is pretty long. I am not aware of plywood that comes in those lengths. I guess one could splice it in the middle somehow. What do most people here do when materials called for are longer than the standard lengths sold?

Or better yet, can this thing be folded? Placing the driver 100+ inches off the floor seems a bit crazy to me.

Jeff

[planet10]

The dimensions are up on the FH site. The Metronome

Doesn't go quite as low as the larger one, but excursion is more controlled and the bass should be tighter.

Leave yourself room for the filters. Their use is very much room and amp/cable dependent.

dave

[planet10]

Originally Posted by jmillerdoc

Which of these (BIB or Metronome) would you personally recommend?

BIBs are almost always folded. Go here to see. Bigger Is Better 'BIB' Cabinet Dimensions - ZillaSpeak

A BIB is about brute force. Maximum bass out of a driver at the expense of ripple. Needs a corner and needs to be an appropriate distance from the ceiling to get the best out of them.

A met won't go as low, but will have more finese.

BIB is very simple to build, but you end up with some pretty big unbraced panels (with the cabinet colouration inherent in that). Add braces to minimize that and it isn't so simple to build any more. (check out the iBIBk for ideas)

The Metronome with its long slim trapezodal panels has inherently low panel resonance. The optional holey driver brace is recommended. It alos wins hands down in terms of aesthetics and WAF.

dave

[jmillerdoc]

I am assuming you are speaking of the preferred:
60/1524
10/6,528
70/45,212
30/762
3 x 2 (76x51)

The driver offset is measured from the top, correct?

What about damping/filling material? I would assume there might need to at least be some felt/wool padding immediately behind the driver. Any other recommended filling?

Yeah, the BIB is BIG, I think WAF will have to be given some consideration.

Thanks,
Jeff

[planet10]

Yes that's the one. Yes you will need some damping. I'd start by lining the walls around the driver with 1/2" wool or Cotton felt, and add some polyfluff above the driver -- you can get a bit denser as you approach the top. Then 1st order fine tuning can be accomplished with polyfluff behind and below the driver.

Depending on room, amp, taste the damping can vary significantly from one application to the next

dave