Fountek FR88-EX

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chrisb

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Joined 2002
fakeout said:
Are any of those plans for the FR88EX applicable to the FR88 (not EX)?
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From the title page of plan set document:
Designed for the FR88ex since we had a case at hand, they should all work with variations such as the FR89ex, FE85, and FR88, the quarter-wave designs having a greater level of tolerance.

If you try them, do let us know.
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while at approx $13 each the FE85 is approx 1/3 the cost of FR88Ex* and would make a logical candidate for a first time build, don't expect much SPL or bass from the smaller driver without HP and woofer support

* I couldn't find a current listing of availability for the FR88 at either of the primary North American resellers - if still in production and available internationally, the freight, duty & brokerage/documentation fees could well double their cost, thereby negating any advantage it might possibly offer. Also note the Ex has 10Hz lower Fs and 3 times rated excursion over the FR88 - performance factors that can't hurt.

Unfortunately or not, the overwhelming prevalence of non CRT video displays has resulted in a dearth of shielded / low magnetic flux driver, so if that's a critical matter, your choices my be limited.
 
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Esaú Cardoso

Member
Joined 2009
v-bro said:
I use the G115 die-cast aluminium boxes (two attached together and drilled through), which have frontal dimensions of 105x145mm Do have a little baffle step compensation filter in there of 1,5mH and iirc 3,9R... Don't ask me why, but these values were what I had laying around... Still work in progress...

Further the notch consists of 6,8R mox, 8,2uF mylar and 0,5mH low resistance ferrite core inductors.
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Very nice design! With this very narrow baffle, I guess you will only have to control the rising frequency response. I think that 0,33mH//8.2uF//4,7ohm would works fine. I would first work in the tonal balance. I think you will not need the BSC filter. But your ears are the judge :)

One interesting thing that I noticed in the implementation of the notch filters in fullrange designs (small fullranges) is that they are generally centred at around 3kHz. The play better but don't actually corresponds to the more linear response in on axis single measurement. I suspect there is something about this frequency that our brain don’t agree with measurements :)
 
v-bro

v-bro

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Joined 2006
Been playing around with the FR89EX some more and it seems these need a lower notch filter, the 1K frequencies seem to stick out more. These might need a pretty wide filter though, centered at 1.5K. Testing facilities are a bit limited right now since I have the speakers at home now, at work I can first EQ them without the notch filter to determine what it should move towards...

The BSC filter did seem to improve things, but as long as the notch isn't fully tuned right I can't really judge the BSC filter.

Funny thing was yesterday I built two more boxes with FR89EX by replacing the FR88EX I had in these cabinets and at first I heard a little rattling noise at higher outputs. Turned out the cones were hitting the grille, whereas with the FR88EX it was fine! They DO seem to move much much more!
 
v-bro

v-bro

Member
Joined 2006
zman01 said:
Not necessarily a good thing, right?
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Might be true indeed, it might be my lack of experience with these, but so far the 88 seems to have the edge in sound quality. Especially voices with the 89 seem far to close and the same notch as I use on the 88 doesn't seem to tame that with the 89..... It seems to be the lower vocal range sticking out too much, hence my suspicion the notch should have a lower centre frequency.

Funny that the on axis frequency response graph they publish on the two drivers seems much alike....
 
v-bro

v-bro

Member
Joined 2006
Oh yes, very pleasant now. Just finished with a beta version of a notch filter, which may be a bit exaggerated, but pleasant, oh so pleasant!

Just amazing how it appears to clean up the high range, just by suppressing the midrange....:p

FR89EX so far:

Two notches, from amp to speaker first one: 10uF-5R-220uH, second one 10uF-20R-220uH...

Some finetuning to do, didn't have many other values at hand now to play with, but this is definitely worthwhile!
 
v-bro

v-bro

Member
Joined 2006
I'm glad I have a pair of Avalon mixing monitors here as a reference, which helps a lot to tweak the sound, they couldn't be more alike, I guess I am running in to physical limitations now LOL! There appears to actually be air now in the highs, and vocals are just incredibly pleasant, I have some wires here to short the filters with and it just goes from yuck to ahhhhhh!
 
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v-bro

v-bro

Member
Joined 2006
DYNABLASTERTUNERS said:
what now, which one is better 88 or 89? :)
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Now I am running ahead in tweaking the 89, the 88 needs some more work before I can really go for a shootout... The 88 seemed best when untweaked, but the bass capabilities of the 89 have are now revealing more, and perhaps that will eventually outperform the 88 overall....

Too early to tell..

MAN I can play loud now without irritations!!
 
S

sayrum

Member
Joined 2011
from what i read, the veravox3 is somewhat differt to the bb3.al.
someone build this fast
VeraTwo
with the bb3.al instead of the veravox3 and then one bb3 got damaged by his daughter. He found a pair of veravox3 to replace the damaged bb3 and wrote about the speakers now sounding better. (xover was designed for veravox)
 
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