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m4rs 16th March 2009 04:25 PM

Fonken Floorstander

I am planning to build a pair of Floorstander MkII with FE127. My amp is an Atoll IN50, a french solid state amp:

I read I needed to put a resistor between my Amp and the fonken because of the output impedance, but what value, and what type of resistor ?



planet10 16th March 2009 05:21 PM

I've heard good things with the atoll.

As to size of R to knock back the damping factor, that is a matter of experimenting. I would start by just playing with wire size. You can start with a pair of 24 g strands of Cat 5 cable (because it is easy to get and cheap), but you may find skinnier works even better -- 30g or skinnier magnet wire would be well worth trying... it is skinny enuff that it gets hard to work with and is easy to damage. If you end up there, winding the pair of connectors around a central core (such that conductors cross as an angle) or sandwiching it in heat seal plastic or packing tape is a good idea for longevity.


chrisb 16th March 2009 09:38 PM

Dave, you mean wire size - Cyrille probably already knows what size wore works best for him

and frankly, with the FE127 , depending on speaker placement (i.e. symmetric corner loading) you might not need series R, or even BSC

m4rs 16th March 2009 10:15 PM

what I was about to ask is how I would know if R is too small. But it seems that it is in the lack of bass I can hear serie resistor is too small. Or am I wrong?

m4rs 16th March 2009 10:15 PM

And yes for the wore I have an idea of what size works for me ;)

chrisb 16th March 2009 10:58 PM

Well Cyrille, I'd be inclined to wait til you actually get the drivers fully broken in (up to several hundred hours of playing time), before you make any decisions as to the final value of any BSC and/or series R.

FWIW, the amps I've been using for musical playback for at least the past 5 yrs or so (during which the Fonken family was conceived and continues to expand), have been almost exclusively low damping factor tube amps. That, using a single strand of #24 CAT5, and the small size of my listening rooms, significantly reduces the need for correction of the type you're discussing.

Having said that, on the one occasion that I did build an enclosure for experimentation with a variety of drivers that might need some series R, I used one of these for ease of inserting/ bypassing values under test:

they could also no doubt be used as a platform for components for BSC components if desired. (i.e. lots of space to directly attach the passive components, or a PC board or even thin piece of masonite/hardboard.)

m4rs 18th March 2009 12:19 PM

ok i'll do that, I just ordered an Amp6 from 41Hz and if I need a correction it'll be easier to switch between the two amps.

By the way thanks to both of you for the fonken design, and for responding to all question on the forum. I work in software development and I'm using linux and free software and I thought it was kind of the same approach. Have you think about licencing your design with one of the creative common licences ?

Best regards

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