The Metronome

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#1,343
nuconz said:
just wondered how the metronome might sound without the port, with an open bottom?
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Besides ripple, no bass.

What are you trying to accomplish?

Many years ago I built some cabinets similar to metronomes except with multiple slit ports that could be wedged open. With these I was able to experiment with varying the opening area from open-->large--->small. It was pretty interesting to hear the bass come in as the aperture area was reduced. I found the best spot, and glued them in to fix it there.

I miss the empirical method sometimes.
 
#1,344
Greg B said:
Besides ripple, no bass.

What are you trying to accomplish?

Many years ago I built some cabinets similar to metronomes except with multiple slit ports that could be wedged open. With these I was able to experiment with varying the opening area from open-->large--->small. It was pretty interesting to hear the bass come in as the aperture area was reduced. I found the best spot, and glued them in to fix it there.

I miss the empirical method sometimes.
Click to expand...

i have some old BOFU drivers and want to 'metronome' them. but, i don't want the enclosures to be 'tied down' to the BOFU only. since the open bottom and PR bottom aren't recommended, it seems good to consider a removable bottom panel and hence removable port(s).
 
#1,348
MattGunn said:
Whilst looking for a reasonably simple but interesting first speaker build project a little while ago I came across the Metronome and followed the trail of information to this excellent thread. I've been reading through it and other information sources ever since and am now fully committed to building a pair.

Whilst researching the various designs for different drivers it became apparent that there was a wealth of information available but that it was well distributed - so much so that it was difficult to find what I was looking for. For this reason I collected all the specifications in this thread and the Frual-Horn website together as I went along and the result is the table attached (.PDF and zipped .xls formats ) - 42 different sets of dimensions in all.

Metronome Dims.pdf

Metronome Dims.zip

Even before I'd finished reading the thread I ordered a pair of drivers - Fostex FF165wk - these have been breaking in for about 4 days now. Once my Birch ply arrives and I've finished the design, the build will start. However I inevitably have questions for those with more experience before I proceed:

I've read numerous things about the performance and range of the FF165wk but am still unsure if it will need an additional tweeter? If so any suggestions?

This is my first venture into serous HiFi and so I am currently using a cheep and basic Sony amp - will this be or can it me made to be remotely usable - would additional series resistance help? I have a feeling that now I've stared on this path I'm going to have to build a new amp in the not so distant future...

Matt
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great work here. just wanted to edit one entry (for the Pioneer BOFU).

p43 #427 suggests to increase the vent length to 4". so this should be a 3/4 vent, not a 4/2 vent.
 
#1,352
nuconz said:
great work here. just wanted to edit one entry (for the Pioneer BOFU).

p43 #427 suggests to increase the vent length to 4". so this should be a 3/4 vent, not a 4/2 vent.
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rotaspec said:
Can you point me to where you found the post with the Metronome Dims files?

I would love to bring my ancient tables up to date.

Thanks
Click to expand...

i started a new .xls and am updating it. eventually i'll go through all the references and correct as needed. it isn't uploaded yet.

anyway here is the requested link:

http://www.diyaudio.com/forums/full-range/85410-metronome-131.htm
 
#1,357
More Mets...

I liked the first pair of Mets so much I decided to make some more - this time smaller and using the Fostex FF105WK, show photographed next to their FF165WK bigger brothers.
Dimensions were optimised using MK's Mathcad and are as follows:
Ao = 1.20" x 0.42" = 0.5"^2
Ai = 6.47" x 4.7" = 24"^2
L = 37"
Z = 18"
Dport = 1.5"
Lport = 3"
This time they were made from hardwood - recycled Iroco lab bench tops planed down to 0.75" thick. They've had about 40 hours breaking in now and are sounding great. I suspect there will be more to come, they are somewhat addictive...
 

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#1,360
Hi,

I have had some Fostex FE207E drivers sitting on the shelf for 4 years 😉

What is the current best proven design for this, is it still dimensions on the frugal-horn page below?:

The Metronome
http://p10hifi.net/FH/images/metronome-207m-v1.gif


What is that vertical plate behind the speaker?
What is the best wood to use, and should I only felt the back?

Sorry if this has all been answered somewhere in the 100's of pages in this thread.


Thanks
 
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