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Old 31st December 2007, 09:47 PM   #1
jrebman is offline jrebman  United States
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Default Fonken for F120A drivers?

This year (2008 that is) I'll be looking to build an enclosure to put my F120A drivers in, and that will be used in my small office space (10.5' x 16' minus a 3' x 6' closet in one corner). Candidates considered so far have been the Metronome, Harvey, Mileva and a basic Fostex BR box. I'd like to explore the possibility of a Fonken but have no idea how to go about determining if this enclosure will be suited to the F120A.

Any advice/ideas welcome.

Thanks,

Jim
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Old 31st December 2007, 10:15 PM   #2
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It is hard to convey how to design these, as i model as a BR looking for a specific shape curve for the roll-off and then lower the Q using a highly resistive port (ie push the box towards aperiodic). Sometimes i have gotten it on the 1st try (Fonken for FE127, µFonken) sometimes it takes a couple iterations (3 with the mFonken)

dave
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Old 1st January 2008, 12:14 AM   #3
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Dave, so are you doing this by ear or are you looking at impedance?
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Old 1st January 2008, 12:44 AM   #4
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Quote:
Originally posted by gmilitano
Dave, so are you doing this by ear or are you looking at impedance?
Modeling to get me in the ballpark, experience to get me the 1st draft and then by ear for tuning. Finally impedance to make sure i'm in the intended ballpark.

I had a quick look at the F120A realier to day, and it looks like it will fit into the miniOnken/Fonken envelope so i'll just need to detail the ports slots.

dave
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Old 1st January 2008, 01:41 AM   #5
BudP is offline BudP  United States
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Dave,

They will be EnABL'd. Do we want to have them come to you and then the entire package to Jim?

Jim,

Are you planning on making the cabinets from scratch, obtaining a kit or a finished Fonken style box? Or have you decided?

Drivers will be ready to ship on the 10th of Jan, next year.

Bud
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Old 1st January 2008, 02:03 AM   #6
jrebman is offline jrebman  United States
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Bud,

As of right now my plan would be to do a scratch build, but if the flat packs become available before then (read, warmer weather) then I'd definitely consider that as well.

I'm sure Dave and Chris would build a great cabinet, but not sure I can afford that -- at least not for a while.

Any listening reports yet?

-- Jim
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Old 1st January 2008, 04:09 AM   #7
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Quote:
Originally posted by jrebman
I'm sure Dave and Chris would build a great cabinet
I'm not allowed to actually build cabinets anymore.... Chris is much better & much faster. That works to create a very symbiotic division of labour.

dave
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Old 2nd January 2008, 02:57 AM   #8
BudP is offline BudP  United States
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Hi Jim,

I have finally listened to the F120A drivers enough to understand how they work.

The sound character is quite open above 1 kHz or so. Reasonably complete transients above 4 kHz and a top end that begins to roll off at about 12 kHz.

There are no indications of poorly utilized metal in the central aluminum dome. And that is quite unusual. I suspect that there may be some damping material or a soft glue in the joint to cone, as there is a pretty strong, narrow, dip in information content below the realm of the aluminum.

There is reasonable information, though they are really just hinting at the fundamental textures, in the right hand of piano's, the bell of drum heads, chest of female singers etc.

This becomes very noticeable in complex Red Book orchestral pieces.

In all, very good candidate's for EnABL. My real challenge will be to get the paper cone to shed more high frequency energy than it does now. With that accomplished they will be a very wide dispersion speaker, probably more so than the Fe 127 eN. Not certain where they will fall in the sweetness realm, but the aluminum dome is very well done. I have good reason tp hope that they will throw a very large sound field with excellent depth and internal clarity.

Bud
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Old 2nd January 2008, 05:48 AM   #9
kmaier is online now kmaier  United States
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Quote:
Originally posted by planet10
It is hard to convey how to design these, as i model as a BR looking for a specific shape curve for the roll-off and then lower the Q using a highly resistive port (ie push the box towards aperiodic). Sometimes i have gotten it on the 1st try (Fonken for FE127, µFonken) sometimes it takes a couple iterations (3 with the mFonken)

dave

Dave,

Are you making enclosure plans available for the uFonken? I have a new pair of FF85K drivers... sounds like an ideal setup for really small.

Regards, KM
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Old 2nd January 2008, 06:34 AM   #10
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Quote:
Originally posted by kmaier
Are you making enclosure plans available for the uFonken?
Yes. Mail me if you need the not quite finished plans.

dave
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