My FM3-based combo amp

Watt McCo

Member
Messages
10,306
Waiting on grill cloth and handle and need to actually finish it, but thought I'd go ahead and start the thread. Will post final pics when its done. Scroll down if you just wanna see the pics.

Executive Summary: its a birch-ply, 22"x20"x10.5" box that holds an FM3, Seymour Duncan Powerstage 170, Line 6 G10 wireless, and 12" Weber Silver Bell Ceramic speaker, all of which is powered by a single IEC cable coming out of the back. It weighs right around 40 pounds. The lid has cutouts in it so you can adjust the volume and tone stack of the 170 and so you can use the tuner on the FM3 and see what preset you are on. The lid also is easily removed with thumb nuts if you need to get in and edit anything on the FM3. it sounds bigger and more focused than the cab I made for use with the HX Stomp because...its bigger, stiffer, and heavier.

The longer story behind it:

As some of you may recall, I made a cab for use with an HX Stomp board last fall: https://www.thegearpage.net/board/index.php?threads/my-28lb-helix-combo-amp.2072803/

I learned a few things from that project. Mainly I learned that pulling a pedalboard out of the back of a guitar cabinet is . . . not wildly convenient. The cab winds up weighted kinda funny because most of the weight is in the bottom. Then you're all squatted over trying to get the thing out of the back and unless you're hyper OCD with cable management, you wind up snagging cables on things -- which precludes keeping the pedal board plugged into the power amp. So setup isn't nearly combo-amp-like -- set down cab. Carefully pull out pedal board while trying not to show off too much crack. Run cable from pedal board to cab. Run cable from guitar to pedalboard. Run power to cab. Check to make sure you didn't dislodge any of your pedalboard cables in the process. And then editing anything on the floor is just...a pain.

So I knew what I really wanted was a rig where the "brains" stay in the cabinet and the only thing I run out of the cab is a small, simple switching system. This makes setup easier and also keeps any volume/tone adjustments or god-forbid actual preset editing up off the floor -- indeed, the way I wound up using the Stomp rig 9 times out of 10 was with the pedalboard sitting on top of the cab.

Like a lot of my projects, this started out with a couple of days of meticulous SketchUp drawing. The final version I came up with there was based on a combination of 1/2" and 3/4" ply that was 10.5" wide. But before I pick up the phone to order some (not cheap) plywood I think "maybe I should check my wood stash before I go spend money on new plywood" and I found a bunch of 5/8" plywood 10.25" wide that was not highest quality, but good enough. And instead of returning to SketchUp I just started building which led to improvisation which led to mistakes, blah, blah, blah. Nobody's gonna mistake this for a Boogie Build, but it ain't bad at all, and it functions great.

As you can see in at least one of these images, there are Fractal-logo cutouts on the sides of the brain compartment to improve ventilation. There's also a hole in the piece that the FM3 sits on directly under the bottom vent. I haven't had any heat build up issues so far at all. Power-on the FM3 is bone simple, the 170 requires a LITTLE bit of a reach into the cab, but not bad. I didn't want to unify them into a single power switch because there will be plenty of times at home where I just hook XLR cables up to output 1 and use the FM3 by itself direct. On the rear view you can see the G10 dual locked to the inside of the cab on the FM3-side -- just reach in and grab the transmitter and plug it into the geetar. I need to get a 2' right-angle guitar cable to go between the G10 and FM3 so that there are no cables sticking out beyond the cab aside from the IEC power cable.

The speaker baffle is glued around its entire perimeter to full-length cleats attached to the four internal sides of the cab -- so its kinda like a Morgan cab or something where the baffle is glued into a dado in the cab only probably even stiffer since the cleats are likely a little bigger than the dado on those cabs is deep. Grill cloth will just be stretched/stapled across the back of the grill cloth frame that then screws onto the face of the cab.





 

texhex

Silver Supporting Member
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837
VERY cool! Much respect, it's definitely a work of art and you sir are a true craftsman.

Hold off on doing a Kemper one, FYI. Could be interesting.

 

Watt McCo

Member
Messages
10,306
VERY cool! Much respect, it's definitely a work of art and you sir are a true craftsman.

Hold off on doing a Kemper one, FYI. Could be interesting.

I've drawn up lots of options for Kemper rack, including some with the rack mounted vertically like on a Tweed amp. I think the best arrangement is to just rack it above the speaker, but pot the handle on the side of the cab rather than the top - adding a 3U rack above a speaker makes for a TALL combo for carrying.
 

texhex

Silver Supporting Member
Messages
837
An all in one powered Kemper/Kab (Kombo?) would be pretty cool but damn, how much will it cost? A pretty penny I'm sure. They have had some very nice developments lately. Hopefully they have another team of people working on a Kemper MkII. Even if it's all the same underlying tech with a modern UI, etc. it would close a bunch of people's mouths.

I'm personally happy with the current rack unit, enjoy how the interface works and the thing sounds spot on with my own profiles and IRs.

That is a cool looking cabinet you've built there, the more I look at it the more I like it.

Why not go with a FX12-X200 speaker? Except I just saw the magnet on one of those, yikes!
 

pcutt

Member
Messages
1,693
Great idea and implementation! Did you consider using a hinged clamshell top with a couple of flush latches? I figure it would be quicker to open her up to get to the gear inside.
 

Watt McCo

Member
Messages
10,306
An all in one powered Kemper/Kab (Kombo?) would be pretty cool but damn, how much will it cost? A pretty penny I'm sure. They have had some very nice developments lately. Hopefully they have another team of people working on a Kemper MkII. Even if it's all the same underlying tech with a modern UI, etc. it would close a bunch of people's mouths.

I'm personally happy with the current rack unit, enjoy how the interface works and the thing sounds spot on with my own profiles and IRs.

That is a cool looking cabinet you've built there, the more I look at it the more I like it.

Why not go with a FX12-X200 speaker? Except I just saw the magnet on one of those, yikes!
Actually, I think the Kemper's UI as is would be the best for this implementation. Until Fractal brings Perform Page to the FM3, it's kinda the worst UI. But this is also a rug that is much more suited to someone that runs simple patches with simple switching since adding anything bigger than a Morningstar MC6 makes the "convenience" pointless. Cost of a powered Kemper rack + Kone + materials to build a cab would likely be a bit less than Kemper + cabinet, but that assumes you don't also have to buy tools, etc.

I like playing through guitar speakers more than FRFR when playing with others, so no on the x200...though I did look up the specs last night I'm case I wind up needing to do acoustic and electric tones with this rig someday, and the cab could likely work okay for it.
 

Watt McCo

Member
Messages
10,306
I wondered about that, too, and I figured some gasketing would take care of it, though.
It doesn't take much effort to get the lid off as is, and my goal is to NOT need to take the lid off much. When I'm at home, I'll just plug USB in the back and edit/create patches on the computer. The EQ in the Duncan powerstage is perfect for general adjustments for the room or guitar or whatever and that's all tweakable without having to remove the lid.
 

Smudge

Member
Messages
78
Two words: thermal management. Worth a little thought, given the criticality of cooling for the FM3. Think natural convection flow and provide openings that will allow that to occur....
 

pcutt

Member
Messages
1,693
It doesn't take much effort to get the lid off as is, and my goal is to NOT need to take the lid off much. When I'm at home, I'll just plug USB in the back and edit/create patches on the computer. The EQ in the Duncan powerstage is perfect for general adjustments for the room or guitar or whatever and that's all tweakable without having to remove the lid.
I see your use case; good point.

I'm considering a related project but mine is a head box to accompany existing 1x12 cabs (I have two - Mesa Thiele and Bogner Cube). Right now I'm in the concept stage for an FM3 or Quad Cortex and am looking at amps. How do you like the PS 170 for this application? Did you consider any alternatives? Any comments on amps for this purpose (good, bad and ugly)? Thanks!
 

Watt McCo

Member
Messages
10,306
Two words: thermal management. Worth a little thought, given the criticality of cooling for the FM3. Think natural convection flow and provide openings that will allow that to occur....
Yeah, I can certainly add some more air flow openings in the lid if needed. And I'm still weighing what to do with the top part of the grill cloth frame (considered some circular cutouts backed with grill cloth material.

So far I've had both amp and processor on and being played through for 2 hours with no noticable heat problems - the fan in the FM3 didn't even kick on.

There are the side cutouts in the cab corresponding to the side vents in the FM3, the vent in the cab below the FM3 corresponding to it's bottom vent, the cutout for the screen, and the back of the FM3 compartment is open with the back of the FM3 being only an inch inset from that back opening. So airflow is actually pretty good as is.
 

Watt McCo

Member
Messages
10,306
I see your use case; good point.

I'm considering a related project but mine is a head box to accompany existing 1x12 cabs (I have two - Mesa Thiele and Bogner Cube). Right now I'm in the concept stage for an FM3 or Quad Cortex and am looking at amps. How do you like the PS 170 for this application? Did you consider any alternatives? Any comments on amps for this purpose (good, bad and ugly)? Thanks!
The 170 is great. I've tried: Mooer Baby Bomb, big Crown PA amp, effects loop return of a class D Peavey bass head, powered Kemper, effects return of a 100 watt 3rd Power Citizen Gain head. The Mooer is a little noisey, is a little annoying because it lacks an on/off switch, and runs out of steam a LITTLE too early...but aside from those caveats actually holds it's own reasonably well against the others. The "good" solid state stuff...all sounds really, really similar. Differences MIGHT start to appear at very loud volumes, but at the volumes I no played them (loud enough to jam with a drummer) they all sounded very similar. Perhaps placebo, but the 3rd Power did seem to add a little j'ne c'est que. But not enough to justify the weight/size/price of tubes, for me.

Tone stack on the Duncan is also super handy - much more convenient than trying to dive into a global EQ to tweak things to a brighter room or compensate for Fletcher Munson, etc.
 

rkbrock

Member
Messages
244
Very nice! Also like the little touches like the "Fractal" logo airflow cutouts. I'm impressed at the weight also, at first I thought it might weight more but 40lbs is decent. I have an original Spidervalve 2x12 combo amp with V30s in it that has almost no resale value. Been thinking of doing something like this with the speakers.
 

Watt McCo

Member
Messages
10,306
Very nice! Also like the little touches like the "Fractal" logo airflow cutouts. I'm impressed at the weight also, at first I thought it might weight more but 40lbs is decent. I have an original Spidervalve 2x12 combo amp with V30s in it that has almost no resale value. Been thinking of doing something like this with the speakers.
With some smarter design/wood choices, could easily lose a few pounds on this while still sounding great and being super sturdy. This one is sufficiently convenient though that I'm not terribly motivated to put in the effort to build a revised design with more patience.
 

vtgearhead

Silver Supporting Member
Messages
1,286
The 170 is great. I've tried: Mooer Baby Bomb, big Crown PA amp, effects loop return of a class D Peavey bass head, powered Kemper, effects return of a 100 watt 3rd Power Citizen Gain head. The Mooer is a little noisey, is a little annoying because it lacks an on/off switch, and runs out of steam a LITTLE too early...but aside from those caveats actually holds it's own reasonably well against the others. The "good" solid state stuff...all sounds really, really similar. Differences MIGHT start to appear at very loud volumes, but at the volumes I no played them (loud enough to jam with a drummer) they all sounded very similar. Perhaps placebo, but the 3rd Power did seem to add a little j'ne c'est que. But not enough to justify the weight/size/price of tubes, for me.

Tone stack on the Duncan is also super handy - much more convenient than trying to dive into a global EQ to tweak things to a brighter room or compensate for Fletcher Munson, etc.
The TC Electronic BAM200 also works fine with tone controls properly set. I normally use a PS170 with my Kemper rack but picked up a BAM locally as a backup / toy. See this for appropriate tone settings:

https://www.thegearpage.net/board/index.php?posts/30994919/
 

Elric

Silver Supporting Member
Messages
4,486
Looks like a fun project. I wish I had the tools/space/skills/time/etc to do some wood working type projects. I am always building rigs and electronic projects (some music but a lot of other stuff too). Love this kind of thing.

In the past I’d pull my Dad in for the “making the box/case/enclosure” part of things as he has always had a home shop... but he is older now and lives farther away as I am the most remote of my family.

Always nice to have something built exactly to your own spec built just for the cost of parts.
 




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