Frugel-Horn Mk3

Joined 2001
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Simplier, smoother, more versatile, a bit taller... discontinuation of FE126e had us starting over, hence FH Mk3.

After a couple iterations and a failed alpha build, we trialled a design at the recent VI diyFEST we are happy with. The alphas were built with removable drivers and we tried it with FE126En, CHR-70, EL70, and Alpair7,

Now we are ready for some beta builds.




Frugel-Horn Mk3 Builds & Build Questions (current plans posted here, see post 1 for where the most current are)
FH3 Picture Gallery

Short cut to the plans:
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Looks more like a rear firing folded voigt with a horn thingie attached to it. Wasn't the original frugel a true horn. That would account for the unique sounds these two cabs make. Still, a very graceful appearing speaker cab- regardless of what you want to call it.
They look somewhat like a folded voigt pipe or straight pipe. I wonder the effect of the curved rear opening? I'm sure it alters the sound but curious if there is a reasoning behind it. This design looks like it can be unfolded so we can all start building things like we used to for the RS 1354 and 1197. I love the simplicity of the folds. Btw, are those BIBs in the background? Also, i wonder if a 'simple' build can be done with 90 degree angles and just an opening at the rear without the curves. Perhaps a less ambitious design but satisfying... then we can all buy drivers and start building again! I'm excited about the new design! Thanks for sharing!

Would that make it a hybrid as it appears that the throat of the horn starts at what would be seen as the exit port on this particular example below: :: View topic - Show me your DIY Speakers !

That would make the rest of the cab a 'tuned' compression chamber where the higher freqs are filtered out by the length and folds of the transmission line prior to reaching the throat of the actual horn.

Would raising the height of the 'throat' to the width of the line proceeding the throat and extending the length of the line to tune the frequency be more in line with the definition of a true horn? Or at least qualifying as a tapped horn?

Still, I love the looks of this new cab. Looks like a fun build. Maybe some variation to accomodate the b20's could be in the works? Now would be the time and palce for that now that they are available on the cheap for expirementation.
V. little time as I've three lectures to write today, but FWIW, some general notes:

-Simplicity was a primary object of this box; it also needed to be compact (while taking feedback from the 1st FH into consideration), and forgiving of different drivers (within reason), largely to help encourage people new to the hobby.
-If a pipe has positive expansion, viz. expands toward the terminus, then by definition it's a horn. FH3 is as much a horn as FH1; albeit a very different variation thereof this time around.
-No, it can't be unfolded. Sorry Jeff, but glad you like the look of it. :) The dimensions of the cabinet are functional parts of the design (to answer your other question, those boxes in the background are a prototype pair of my Maeshowe cabinets that Dave & Chris are playing with).
-Back-horns don't actually possess compression chambers per se (save in the case of reactance-annulled designs). FH3 began as a single-tapped hypex horn with the expansion briefly choked at one point to provide a degree of low-pass filter effect (per Olson & a little pre T/S BR design). Fo however is actually little affected.
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Looks very nice.

will there be one of those large baffle thingies to go on the front as an upgrade ?

what a supra idea!

There was not quite enough time to execute that for this particular demonstration, (the 4 pairs for the driver swapping on Maeshowe took priority), and we also wanted to test a range of (4 different) drivers in this pair to confirm versatility. The (latest version) FE126E was quite impressive indeed.

Interested builders might like to know that due to the curved side panels of this latest version, when using BB plywood a little creativity is required to yield all the parts from a single 5x5 sheet and retain vertical grain direction on the most visibly exposed parts ( sides/front/ top), but then grain pattern/matching is a particular hobby horse of mine.

In the case of our first build, accumulated offcuts from other projects were used, so the following cut plan was after the fact. For the side panels I made an MDF template, rough cut with jig saw, then finished with router and pattern bit.

a 4x8 sheet would have lots of room to spare


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How did you like the Mark Audio Drivers in this box?

There was too little listening time at the tail end of the 3 days of craziness that is the "festivus",* so our initial impressions need to be tempered, but I personally preferred the FE126En in this enclosure

In other designs, such as Maeshowe, or the appropriately dimensioned "Ken", the Alpair7 is certainly an eye-opener

*only a brief overview of the organized chaos of such events:
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Joined 2001
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FH3 as we got to is a big vent mass loaded tapped horn (hypex executed with 2 conical sections)

Plans are ready to be released to a few brave beta testers (actually anyone that wants). Damping for different drivers, alternate construction methods wrt the "point", suprabaffles, deflectors all need exploration. Measures in room. Documents -- a single sheet so far -- need fleshing out.

The Mark Audio drivers sounded good. The A7 was my favorite in them. Some may find that the bass may need a bit of reduction (more damping, pulled more out into the room).

I was curious as to whether the 'choke' in the hypex horn could be raised to the point that it would be removed. I understand the choke acts essentially as a low pass filter but would increasing the line length (thus the height of the cabinet) do the same thing?

I'm terrible at modeling these things and I'm sort of a noob when it comes to the design process so normally I'd just go build the thing (modified) and report back my findings if they were particularly favorable. Too many irons in the fire at the moment.

You'll have to forgive all my queries and speculation- I'm not trying to take away from what I see as a physically marvelous looking speaker. It has, however, sparked my imagination enough to build a variant of it, a little taller perhaps, but similar in other respects. I figured that you, as its initial designer , could verify whether my vision, variant, spawn or whatever is worth pursuing: a folded tapped hypex horn, very similar in design but less of (or none) a choke.

I would be interested in trying to build what you've got there, as is though, maybe to be used as a reference for further design.

No response to my querie regarding something similar but for the BOFU's?
FH3 as we got to is a big vent mass loaded tapped horn.

Plans are ready to be released to a few brave beta testers (actually anyone that wants). Damping for different drivers, alternate construction methods wrt the "point", suprabaffles, deflectors all need exploration. Measures in room. Documents -- a single sheet so far -- need fleshing out.


How would they be without the curved back? How do I get the plans?:)