Frugel-Horn Mk3

Big Wood Studio
Found it, very nice.
Bob, can you tell what are those L shape pieces of wood for?

Hey Cindra,

Those are squares to help with the assembly. I figured not everyone might have appropriately sized squares on hand so I cut some out of the waste and send them along. At no extra charge of course. I may have mentioned I am making little changes in the kits as I go along to make things easier for the consumer and for me. The squares was one thing, and now I am adding marker holes on the inside of one of the "non-dado" side so that one can easily screw the "second side" on if you want to play around with the stuffing/tuning over time without having to rely on clamping the side on. This will help the WAF during the testing phase of the job. Of course, if you want to just go right to gluing the side w/o the screws for testing, no one will ever know they are there.

And thanks for the kind words!!

Yes, dados would have to be calculated into the cut. On our flat-paks the indife dado meant 5mm wider interior panel and 10mm wider external panel (not a god idea to have a 2nd interior dado on the other side).

No chafer or roundover is worst for diffraction, the bigger the better (limited to what you can fit), up to exotic suprabaffles that have the top of the FH looking like the mid cabinet off a B&W Nautilus or an Eclipse.



Short answers:
a) As long as internal width and other dimensions are maintained, thickness of external materials and depth of dadoes could be adjusted . So, just add the depth of any dadoes to the width of the lateral pieces. While it’s been almost two years since my last build, set of numbers I’ll likely remember for a while yet is 140, 145 and 150mm. Tight fitting dadoes on both side panels would require more attention during assembly that I ever had patience for.
b) Unless net thickness at joints of external panels (sides/top/front baffle) is substantially increased, the radius of practical round over - or bevel/chamfer - would be almost entirely cosmetic. Possibly measurable, but I highly doubt audible.

One of the early experiments by Planet10 was to add short wrap around side panels when implementing a removable baffle - such as seen in one of Bob’s options - and I can’t recall hearing an improvement. Driver selection and placement/ toe-in made far more of a difference.
So is the width of the supra baffle critical? I made a set for a customer and he wanted the sb to be 18mm wider on each side. I didn't see the point of the extra width, especially since it is relatively a small difference, but he was paying me to make them so...

And if it does make a difference, why not extend the top of the baffle as well as the sides? I think that the sound waves emitted by the driver would be circular, and grow in diameter as they leave the front of the driver. If this is the case, wouldn't you want to increase the height of the baffle also? Below the driver we have a very large baffle, so does any of this matter? I get the idea of an infinite baffle having a big effect but on this scale???



New member
2020-10-23 6:41 pm
I’m looking to purchase my first DIY kit and I’m considering the floor standers from KJF, specifically the Pensil 11 or the Frugel Horn Mk3 or XL.

I’ve watched the Youtube construction videos of the Horn by Stefan Whatcott and I’m confident its within my abilities but I see there is no video of the Pencil build?

From reading various forum comments I understand the Pencil may be more complicated to build given the internal bracing. If this is true I’m thinking I should choose the Horn as my first build?

This leads me onto the sonic differences between the two designs, if any? I can’t seem to find any info on how they may differ?

They will be used in my living room either side of my TV about 210cm apart. They can be placed so the front of the speaker is about 70cm away from the back wall giving a listening position 280cm away. Plus I can bring them further out into the room for critical listening giving an equalateral set-up.

My room size is 4x5m and has soft furnishings such as carpet, etc.

I mostly listen to rock, hard rock and some metal. I also listen to a variety of other genres such as EDM, world and reggae. I don’t listen to jazz or classical.

I understand the Pensil 11 and Horn XL use 6.5” drivers and the Horn Mk3 uses a 4” driver.

Any advice on which option to choose?

PS This is my first post so please be gentle. I’d like to make a few posts with pics throughout the build as well.



Paid Member
2011-02-04 11:35 am

If your music mostly consists of rock, metal, EDM and reggae, then a 2 way/multi-way system would suit you better. I speak from experience.:)

If you would like to build a 2 way speaker using a wide-band (aka full-range), then you can explore designs known as FAST or WAW, that are wide-band drivers crossed over to mid-bass/woofers. The wide-band driver does the duty of the mid-range and tweeter, and the mid-bass / woofer takes care of the low frequencies.

There are traditional 2 way/multi-way designs also that will serve you well, but that will be a discussion for the multi-way forum.


Paid Member
2016-12-20 4:53 am
Huntington Beach, CA
Don't go FH3/ Fostex for your music ( don't know for other speakers in FH3 ) , they are very good for vocals / jazz , not for metal

So a slightly different view. I have a pair of Fostex ff105wk in bookshelf size boxes paired with a subwoofer. These are my first DIY or fullrange speakers and my system is very modest. I will say if you are looking to learn about speakers and systems a set of fullrangers can be a lot of fun to start out with. I have experimented with BSC, zobel networks, passive and line level filters, stuffing and driver treatments with these speakers. Powered them with an off the shelf Onkyo amp, DIY Mod86, and now a tube amp. Having no crossover to start with has made it simple. So if part of your goal is to experiment then you might still consider the FH3.

I am sure a quality 2 way design would sound better with rock and EDM but I will also say I do enjoy turning up the volume while listening to punk or EDM on my system when the opportunity presents itself.
I use my pensils (alpair 10p) for all sorts, and very happy with them. I chose pensils over horns due to space limits. As for difficulty, if you buy the flat pack from kjf they will be about the same. The difficulty lies in cutting and fitting the brace to the right size. Afaik kjf cuts their parts using cnc and everything is fitted with dadoes so it will be a breeze either way. Very nice kits those...