Speaker Building With a CNC Machine

[Poultrygeist]

Percision cutting is perhaps the hardest part of any DIY speaker build. I have a friend who has access to a CNC milling machine like the one below and I hope to have him make the cuts for a pair of Frugel-Horn Mk3 which use the new Fostex FE126En. I don't have the link for these free plans but I'll find it and post it later.

http://www.youtube.com/watch?v=mWnM9U9R27A

[Poultrygeist]

Here are the plans for the Frugal-Horn Mk3 - Ask PoppaC how good these puppies sound

http://homepage.mac.com/tlinespeakers/FH/beta/FH-Mk3-betaDoc-251010.pdf

[Poultrygeist]

Yipes! The CNC routered Frugal Horn flat packs will be cut this weekend. I hope the DIY gods look favorably on this humble undertaking.

[atomicAdam]

can't you just make that box out of wood? why you going the YG route?

[Poultrygeist]

The CNC routered flat packs will be 3/4 inch MDF which IMO sounds better than plywood and is a heck of a lot cheaper. All the plywood I see these days is full of voids.

It's hell to get a finish on MDF but who knows maybe I'll learn to veneer.

[atomicAdam]

I didn't know a CNC could be used on wood - I always saw them being used on aluminium. But I suppose there are all kind of things I've not seen yet.

[Poultrygeist]

I would think many commercial speaker companies use CNC machines since the cuts never deviate from one run to another. My dentist has one that mills a perfect crown ever time :-)

I picked up my Frugal Horn flats today from a guy who does huge contracts for kitchen cabs and who happens to be a vintage Klipsch fanatic. He said he stored all the settings for the FH cuts in case they sound good. He also said he'd veneer mine once I get them together. If you can believe the huge thread at DIY Audio the Mark 3's are gonna be special.

I was surprised at how small and dainty the FH will be but everything seems small compared to my towering OB's and those heavy assed Omens. Adam, watch out moving those OD's around cause hernias ain't no picnic.

[atomicAdam]

I would think many commercial speaker companies use CNC machines since the cuts never deviate from one run to another. My dentist has one that mills a perfect crown ever time :-)

I picked up my Frugal Horn flats today from a guy who does huge contracts for kitchen cabs and who happens to be a vintage Klipsch fanatic. He said he stored all the settings for the FH cuts in case they sound good. He also said he'd veneer mine once I get them together. If you can believe the huge thread at DIY Audio the Mark 3's are gonna be special.

I was surprised at how small and dainty the FH will be but everything seems small compared to my towering OB's and those heavy assed Omens. Adam, watch out moving those OD's around cause hernias ain't no picnic.

This is true - I found a good amount of foot under the box will help. Honestly - so far - if you like the sound of the Omen Defs - my only complaint is the box. I think the finish is easy to damage and it is difficult to find a place to grab them for positioning.

[Poultrygeist]

The Frugal Horn Mk3 build is on hold as Madisound's Fostex drivers are on back order.

[atomicAdam]

http://gallery.audioreview.com/data/audio//500/medium/P2130004.JPG

Well blow me down! That is sweet looking!

I totally curious how it will sound when you are finished. How much is this costing you? And when can I get a demo set to review? :ihih: :ihih:

[Poultrygeist]

http://gallery.audioreview.com/data/audio//500/medium/P2130011.JPG

The flat packs for two speakers including a sheet of 3/4 MDF and CNC routing came to $120. The Fostex FE126En drivers cost $43 each. So I'm looking at around $200 which ain't bad considering commercially made back loaded horns can fetch $800+ with the same Fostex drivers and IMO won't sound any better.

I've got some trim cutting and gluing left to do. Plus stuffing the V with acoustifil and gluing batting/cotton felt around the cut outs and on the rear of the magnets.

The drivers won't get here for another 3 weeks so by then I should have everything ready for them to just drop in.

[Poultrygeist]

http://gallery.audioreview.com/data/audio//500/medium/P2130010.JPG

Here is the rear view of the Frugal Horn Mk3.

[Hyfi]

I didn't know a CNC could be used on wood - I always saw them being used on aluminium. But I suppose there are all kind of things I've not seen yet.

Just think of a Computer controlled Router and you just imagined a CNC machine. I have machined all kinds of materials from metals to plastics to wood in my past life as a Toolmaker. As long as you have the right tool and run the correct RPM and feeds, it will machine wood as if it was metal.

And yes, probably all speaker MFGs use CNC, which just stands for Compterized Numeric Control, for making the cabinets and speaker cutouts in todays world.

Cool speakers being made here for sure.

[atomicAdam]

Just think of a Computer controlled Router and you just imagined a CNC machine. I have machined all kinds of materials from metals to plastics to wood in my past life as a Toolmaker. As long as you have the right tool and run the correct RPM and feeds, it will machine wood as if it was metal.

And yes, probably all speaker MFGs use CNC, which just stands for Compterized Numeric Control, for making the cabinets and speaker cutouts in todays world.

Cool speakers being made here for sure.

I hear you - I've just only seen CNC in use on metals and plastics. Just figured wood was done by hand. But......

[Poultrygeist]

I believe there's a video on the Zu website that shows a CNC machine routing speaker cabinets from MDF.

[atomicAdam]

I believe there's a video on the Zu website that shows a CNC machine routing speaker cabinets from MDF.

Yes I suppose you are correct.

I saw that video at the debut at THE SHOW this year. I don't think any of the Zu guys had seen it either so I got to watch their video and reaction to it. It was pretty fun. Should have had some shots... hummmm....

[Poultrygeist]

Hope to have the Frugal Horn's internals gluded up this week. I'm actually making an extra pair for a friend. The acoustistuff from Parts Express should arrive this week but the Fostex drivers are still on back order.

[Poultrygeist]

Everything is glued up now and the seams are Bondo'ed. Waiting on the drivers. I'll probably start a new thread with before, during and after shots of the build.

[atomicAdam]

Everything is glued up now and the seams are Bondo'ed. Waiting on the drivers. I'll probably start a new thread with before, during and after shots of the build.

I'm getting the build bug too - except I just looked under my car and oil appears to till be leaking out of the spot I paid $300 to fix last week. YAY - spending cash go bye bye.

[Dual-500]

Accurate cuts are one part of the equation - the other is assembly. It takes a skilled hand to "Get it right".

Seems you have a handle in it for sure.

Nice project. :thumbsup:

[Poultrygeist]

Got the drivers today, installed the binding posts, hook up wire, cotton felt, and acoustistuff. Clamped the sides together for a brief listen and they sound better than I ever could have imagined. Stay tuned for a new thread and some pictures.

[swan24]

Very neat speakers... I've done some woodworking / finishing, and the best way short of veneering to finish MDF is to spray [not brush] a shellac sealer on the exterior first... A few coats are in order to really seal the pores... Then you can topcoat with a finish of your choice... I personally like a spattered paint finish, which is also sprayed on... Looks professional in all respects... One thing I'd watch out for is where the butted edges meet and are exposed to the exterior... These should be filled with some kind of non-cracking wood filler, then sanded well before sealing... (m.)

[Poultrygeist]

Using auto body filler ( Bondo ) to fill all seams and sanding flush - when finished the seams shouldn't show. Will be spraying several primer and finish coats ( black ) hopefully this weekend.

[daveuzuk]

The CNC routered flat packs will be 3/4 inch MDF which IMO sounds better than plywood and is a heck of a lot cheaper. All the plywood I see these days is full of voids.

It's hell to get a finish on MDF but who knows maybe I'll learn to veneer.


Prime it - sand it - undercoat it (automotive) - wet and dry it - spray paint it (get the spray shop to do it) two pack.

You can do it any car paint colour you like and have a finish as good as your car (automobile).

[atomicAdam]

Prime it - sand it - undercoat it (automotive) - wet and dry it - spray paint it (get the spray shop to do it) two pack.

You can do it any car paint colour you like and have a finish as good as your car (automobile).


I thought you were gonna bust out a daftpunk version of painting some speakers! Dang..

[Poultrygeist]

The Fugal Mk3 are completed with pictures in my gallery. Would love to post them in a new thread but haven't mastered that yet. I can post pics on other forums till the cows come home but not here.

First impressions: lots of finese and resolution with better bass than I ever expected. The Frugals are the most fun you can have for $200 with your pants on.

[swan24]

The Frugals are the most fun you can have for $200 with your pants on.


A poultry sum, that... (m.)

[atomicAdam]

http://gallery.audioreview.com/data/audio//500/medium/P3210006.JPG

http://gallery.audioreview.com/data/audio//500/medium/P3210009.JPG

http://gallery.audioreview.com/data/audio//500/medium/P3040011.JPG

[atomicAdam]

Freaking awesome! I so want to build a pair of speakers myself now!

[Poultrygeist]

Thanks Adam for posting my pictures.

These horns only require 7 boards per enclosure and Lowes or Home Depot will make all the cuts except the curved sides which can be done with jig saw and a steady hand.

The 1/2 inch cotton felt glued to the driver compartment is carpet backing from an old Ford truck. Pillow stuffing ( poly-fluff ) in the V chamber can work as well as the more expensive acoustistuff that I used from Parts Express. The drivers cost $45 each.

I've had them playing FM non-stop in my garage for 4 days now and they're really opening up. I am just amazed at how good these puppies sound to the point that I'm actually afraid to bring them in the house and do an A/B with the Zu's.

Even though these horns cost me so little they'll end up costing me more as now I feel obligated to spring for an 2a3 SET amp.

[Poultrygeist]

I went ahead and upgraded to a low powered 2a3 SET amp which is proving to be a wonderful match for these horns as well as the Zu Omens.

[atomicAdam]

I went ahead and upgraded to a low powered 2a3 SET amp which is proving to be a wonderful match for these horns as well as the Zu Omens.

Very nice. How would you say a 2a3 amp compares to something w/ EL64 or EL34 or KT88 or 211 or 300b -

I've never heard a 2a3 amp that I can remember.

[Poultrygeist]

The EL34 and KT88 are pentodes most often used in push pull amps while the 2a3 and 300B are direct heated triodes commonly used in SET amps. The push pull amps while having a power advantage have a downside of odd order harmonics. Most push pulls do not have the detail and sweet warmth of an SET. I've heard many push pull amps but none so far has offered the seductive qualities of the SET when driving high efficiency speakers.

The 2a3 is sometimes called "the mother of audio tubes". It's an old design originating from the 1920's. The 2a3 SET is characterized by super sweet detailed mids and highs While some find it lacking in bass, with the WE tubes in my 2a3 I haven't found that to be the case. I love hearing the "wood" in the jazz double bass and I couldn't want for anymore.

The 300B is probably more popular than the 2a3 as it offers more power than the 2a3 and will drive less efficient speakers. It usually offers more bottom end while the 2a3 tends to be more detailed, refined and musical. The 2a3 is more about mids, highs and transparency while the 300B is more about bass and slam. For rock the 300B may be the better choice but for small group jazz, string quartets and vocals the 2a3 has no peer IMO. The 2a3 has an almost a cult like following and you'll often read quotes like "it's impossible to make a bad sounding 2a3 amp" or "I've never heard a 2a3 I didn't like". The one caveat is that in order to appreciate a 2a3 one must have high efficiency speakers. The 2a3 is truly a match made in heaven with efficient full range single drivers such as the horns and the Zu's.

While both big coke bottle 2a3/300B tubes can generate lots of heat, the 300B runs hotter and cost more than the 2a3. The tubes only have 4 pins with 2 larger than the others. Dared sent a pair of white gloves to install those big tubes which was a nice touch.

Someone made the following comparison between the 300B SET and 2a3 SET: "The 2a3 is a beautiful and elegant woman while the 300B is an energetic young man"

[atomicAdam]

awesome feedback - thanks very much - i really want to hear a 2a3 amplifier now. That sound just like what I really loved about the Meloday AN211 amp I've had in.

Once up in Oakland we are going to be apartment dwellers again. I'm going to try to procure a pair of the Zu bookshelf speakers for review and a 2a3 amplifier.

[atomicAdam]

What do you think of this? I'd guess based off your above description this could be said to be a 'tom boy' -

http://cgi.ebay.com/Music-Angel-King-300B-2A3-vacuum-tube-Power-Amplifier-/170488838314?pt=LH_DefaultDomain_2&hash=item27b1ed38aa#ht_3994wt_1158

[Poultrygeist]

The Music Angel looks nice but here's mine:


http://cgi.audiogon.com/cgi-bin/cl_sold.pl?ampstube&1304893777