DIY Rythmik G22 Cabinet vs. Turn-key Sigberg 10D (Seeking Advice)

[Timcognito]

Buying parts to wait indefinitely for a rare, discontinued cabinet to pop up used isn't a viable strategy for me either.

I meant a whole used G22 and the parts are for both should something fail. You were so set on that model hope you don't regret not taking the chance. No hard feelings on my part. You should go with your gut and avoid the risk.

My neighbor had a '69 Dino on blocks in his garage, all original 26k mile. I begged him to sell it to me for years. 20 years ago he acquiesced, $50k (a good rate for a barn find) and I got my wife to say yes but our house was in middle of remodel waiting for a garage, I chickened out. He passed two years ago and his window sold it for $250K

 

[marked sound]

I get you think the G22 is a magic subwoofer, it's not, everything I said is true. Sealed subs are EQd for extension, and that's what the Rythmik amp does. The amp has a servo sensor and so does the driver, that's it just an additional cost that does provide a small benefit. There is a reason that there isn't very many servo subs or speakers available and it's not because it's not complex as servo circuits have been around a long time.

I'm not trying to be disparaging, just honest and I'm trying to be helpful for *you*.

Edit: I don't agree with Paul McGowan on very much, but I do here.

I read your post and watched your video. However, I have agonizing this for the last couple of days and read a lot.

I appreciate that you are trying to be helpful, but you are confusing pre-programmed DSP/EQ with a real-time electromechanical feedback loop. They are completely different engineering principles.

A standard sealed sub uses DSP to force extension by altering the input signal based on a static, predicted model. The amplifier sends the power, crosses its fingers, and hopes the driver behaves.

Rythmik’s Direct Servo is a closed-loop system. The sensing wire on the voice coil generates a real-time back-EMF voltage that tells the amplifier's comparator circuit exactly where the cone is relative to the input signal, instantly correcting for voice coil thermal compression, driver non-linearities, and—crucially—changes in the internal air-spring compliance of the cabinet.

This brings us right back to the cabinet fabrication problem. If a DIY box has slight structural flex or micro-leaks under high pneumatic load, the internal pressure dynamics change dynamically. In an open-loop sub, the DSP doesn't care; it just keeps firing blindly. In a servo sub, those structural variances directly alter the feedback voltage on the sensing wire, forcing the amplifier to actively try to correct for a flexing box.

There is a reason major high-end manufacturers like Velodyne, Genesis, and Rythmik engineered these systems: it significantly reduces distortion and group delay. But it only works if the enclosure's physical air volume matches the exact pneumatic parameters the amplifier circuit was component-matched to simulate. It’s not 'magic'—it’s strict, unyielding physics. That is why the physical build tolerances matter so much more here than they do on a generic MDF box.

 

[Shiva]

another sub company that makes interesting designs is GSG..both flat packs and finished subs. this is obviously a bit overkill, but here, a short vid of a dual opposed 24" driver subwoofer... I would like to hear that myself....

 

[marked sound]

I meant a whole used G22 and the parts are for both should something fail. You were so set on that model hope you don't regret not taking the chance. No hard feelings on my part. You should go with your gut and avoid the risk.

My neighbor had a '69 Dino on blocks in his garage, all original 26k mile. I begged him to sell it to me for years. 20 years ago he acquiesced, $50k (a good rate for a barn find) and I got my wife to say yes but our house was in middle of remodel waiting for a garage, I chickened out. He passed two years ago and his window sold it for $250K

So are you suggesting i buy the parts in case a broken g22 shows up on the market?

 

[Timcognito]

So are you suggesting i buy the parts in case a broken g22 shows up on the market?

or your NOS breaks. Option to buy NOS use and wait for second used G22. Parts are nice to have for a discontinued model. I have a whole Nakamichi System One with second and thirds of its four components some working some not of those.

 

[Everett T]

I read your post and watched your video. However, I have agonizing this for the last couple of days and read a lot.

I appreciate that you are trying to be helpful, but you are confusing pre-programmed DSP/EQ with a real-time electromechanical feedback loop. They are completely different engineering principles.

A standard sealed sub uses DSP to force extension by altering the input signal based on a static, predicted model. The amplifier sends the power, crosses its fingers, and hopes the driver behaves.

Rythmik’s Direct Servo is a closed-loop system. The sensing wire on the voice coil generates a real-time back-EMF voltage that tells the amplifier's comparator circuit exactly where the cone is relative to the input signal, instantly correcting for voice coil thermal compression, driver non-linearities, and—crucially—changes in the internal air-spring compliance of the cabinet.

This brings us right back to the cabinet fabrication problem. If a DIY box has slight structural flex or micro-leaks under high pneumatic load, the internal pressure dynamics change dynamically. In an open-loop sub, the DSP doesn't care; it just keeps firing blindly. In a servo sub, those structural variances directly alter the feedback voltage on the sensing wire, forcing the amplifier to actively try to correct for a flexing box.

There is a reason major high-end manufacturers like Velodyne, Genesis, and Rythmik engineered these systems: it significantly reduces distortion and group delay. But it only works if the enclosure's physical air volume matches the exact pneumatic parameters the amplifier circuit was component-matched to simulate. It’s not 'magic'—it’s strict, unyielding physics. That is why the physical build tolerances matter so much more here than they do on a generic MDF box.

I give up, lol. Good luck

 

[kemmler3D]

If you can get one G22, just take the drivers out, measure the internal bracing carefully, use that to make plans, then take it to a local cabinetmaker and explain that it needs to be cut to very tight tolerances and glued airtight. You might be able to leave the existing G22 cabinet with them as a reference.

I don't think it should be very hard to find a shop with a CNC table, and I don't think you need a special one to cut MDF within a fraction of a millimeter. You probably won't need any 3D shapes cut, so I don't think your job will daunt most cabinetry shops.

Gluing for airtightness isn't trivial but it's not rocket science either. It doesn't need to be airtight like a submarine, just enough that any leaks are negligible compared to the pressure difference the drivers create inside the cabinet.

It does sound like you're trying to talk yourself out of this project, and if you don't trust yourself to disassemble a sub and put it back together again, just go with the Sigberg units.

But I think it's doable, maybe worth the effort, especially if you feel that the subs in question are an excellent value.

 

[Norcal]

I give up, lol. Good luck

There’s a trend. Ask for advice, then argue with the advice-givers. Ignore.

 

[OldHvyMec]

OP, the box that Rythmic is using is not too difficult to build. 3/4" doubled to 1.5 on both ends where the drivers are. The amp is sealed in a side pocket and adds a little bracing or ribs about every 6-8 inches. 1" X 3/4 ribs will be fine. You could add those ribs to the amp separator plate if you really want to go out of your way. I assure you, there is nothing fancy about any sub box other than the fancy bracing cut by CnCs. Rounded corner joints require a good router, table shaper, or jointer.

BTW the interior size just needs to be close; there is absolutely no reason to be spot on with interior volume, or they wouldn't be using batting/stuffing or even shag carpet glued to the interior walls for damping.

You can also paint or treat the interior with @sound Coat, FlexSeal, or peel-and-stick dampening material. For any and all resonant issues that there WON'T be if you just brace, BUT it is a nice feature to do the knuckel rap, and it sounds like you're tapping on green concrete or curb and gutter.

Before CNCs, people used simple band and jigsaws with table saws and a dado blade or routered slots to fit the bracing. If they did that.

Some of the best cabinets I've ever seen were cut with skill saws and clamped guides. They all used simple routers to do the roundovers or whatever you want to add to a cabinet.

If you really want to build a killer cabinet, use 11-14 ply Baltic birch and either MDF or HFD, and laminate the two with silicone. Just coat the two pieces with silicone adhesive and do it in lines so most of the air will escape, jack up a car or SUV, and lower it onto the two pieces, for a day or two. Make sure the laminates are oversized and trim to make the box.

You can route, shaper, or jointer to cut in 3/4 or 1" square stock for extra-hard corners if you want. I have built a few boxes that I added oak or apitong to the corners.
They were so strong that you could jack up a 14,000-pound conventional cab tractor and set a single or dual on the cabinets. I have some pics of a dual 3/4 Baltic Birch cabinet for the sub/bass/mid. 42X12X16. You would wear yourself out trying to break those cabinets apart with a 20lb long-handle sledge. After I glued them, I added #8 SS 2.5" torex fastners that are slightly raised with the pan head on 6" centers all the way around the front and rear baffles

Those cabinets had matching satellite cabinet to make up a 7.X cabinet set. I still have them. I never finished them because I had a dog that had been with me for 16 years (Toy Fox) and he would sleep in the sub-section of one of the cabinets. He passed, and I never had the heart to close that opening where he spent countless nights with me, hand-fitting those cabinets.

That same type of cabinet is in my washroom, and a mahogany/pine set is still in my kitchen 45 years later.

The point is, there is nothing a skill saw, tape measure, glue, and a few sketches can't accomplish, especially when it comes to sub/bass cabinets.

Now, the mirror finish, whether it's an automotive paint or clear coats over hardwood veneers, is a whole different process, but I've done my fair share of those, too.

For the cost of that double 10 you're looking at, you can make 2, maybe 3 cabinets with divers and 800watt servo amps. Once again, the finish is where people get picky.

Fruit for though, ay?

Best regards

 

[marked sound]

There’s a trend. Ask for advice, then argue with the advice-givers. Ignore.

nothing i said wasn't well rationed

 

[marked sound]

If you can get one G22, just take the drivers out, measure the internal bracing carefully, use that to make plans, then take it to a local cabinetmaker and explain that it needs to be cut to very tight tolerances and glued airtight. You might be able to leave the existing G22 cabinet with them as a reference.

I don't think it should be very hard to find a shop with a CNC table, and I don't think you need a special one to cut MDF within a fraction of a millimeter. You probably won't need any 3D shapes cut, so I don't think your job will daunt most cabinetry shops.

Gluing for airtightness isn't trivial but it's not rocket science either. It doesn't need to be airtight like a submarine, just enough that any leaks are negligible compared to the pressure difference the drivers create inside the cabinet.

It does sound like you're trying to talk yourself out of this project, and if you don't trust yourself to disassemble a sub and put it back together again, just go with the Sigberg units.

But I think it's doable, maybe worth the effort, especially if you feel that the subs in question are an excellent value.

Thanks. This was a very balanced and thoughtful reply by someone who sounds like he knows what he is talking about.

Truthfully I don't trust myself to disassemble and put a sub back together and not screw something up, or not have things tight enough, or get the measurements wrong etc. Which is might seem strange because I have taken apart and put back together many computers / laptops.

In my opinion the G22 was one of the best subs for music ever made. Direct servo, dual opposing, not too big, dug down to 14 Hz. I just don't feel comfortable building one. If two were for sale id jump on it. If i knew used ones came up for sale often i'd also go the G22 route. I could be waiting years for a used one, and if one did came for sale, would the person be willing to ship?

The Sigberg 10D is also dual opposing and also draws little power which I need for my old wiring, and contains audiophile amps and drivers. It's just it's an expensive small niche sub. I will figure what I will do soon.

 

[marked sound]

OP, the box that Rythmic is using is not too difficult to build. 3/4" doubled to 1.5 on both ends where the drivers are. The amp is sealed in a side pocket and adds a little bracing or ribs about every 6-8 inches. 1" X 3/4 ribs will be fine. You could add those ribs to the amp separator plate if you really want to go out of your way. I assure you, there is nothing fancy about any sub box other than the fancy bracing cut by CnCs. Rounded corner joints require a good router, table shaper, or jointer.

BTW the interior size just needs to be close; there is absolutely no reason to be spot on with interior volume, or they wouldn't be using batting/stuffing or even shag carpet glued to the interior walls for damping.

You can also paint or treat the interior with @sound Coat, FlexSeal, or peel-and-stick dampening material. For any and all resonant issues that there WON'T be if you just brace, BUT it is a nice feature to do the knuckel rap, and it sounds like you're tapping on green concrete or curb and gutter.

Before CNCs, people used simple band and jigsaws with table saws and a dado blade or routered slots to fit the bracing. If they did that.

Some of the best cabinets I've ever seen were cut with skill saws and clamped guides. They all used simple routers to do the roundovers or whatever you want to add to a cabinet.

If you really want to build a killer cabinet, use 11-14 ply Baltic birch and either MDF or HFD, and laminate the two with silicone. Just coat the two pieces with silicone adhesive and do it in lines so most of the air will escape, jack up a car or SUV, and lower it onto the two pieces, for a day or two. Make sure the laminates are oversized and trim to make the box.

You can route, shaper, or jointer to cut in 3/4 or 1" square stock for extra-hard corners if you want. I have built a few boxes that I added oak or apitong to the corners.
They were so strong that you could jack up a 14,000-pound conventional cab tractor and set a single or dual on the cabinets. I have some pics of a dual 3/4 Baltic Birch cabinet for the sub/bass/mid. 42X12X16. You would wear yourself out trying to break those cabinets apart with a 20lb long-handle sledge. After I glued them, I added #8 SS 2.5" torex fastners that are slightly raised with the pan head on 6" centers all the way around the front and rear baffles

Those cabinets had matching satellite cabinet to make up a 7.X cabinet set. I still have them. I never finished them because I had a dog that had been with me for 16 years (Toy Fox) and he would sleep in the sub-section of one of the cabinets. He passed, and I never had the heart to close that opening where he spent countless nights with me, hand-fitting those cabinets.

That same type of cabinet is in my washroom, and a mahogany/pine set is still in my kitchen 45 years later.

The point is, there is nothing a skill saw, tape measure, glue, and a few sketches can't accomplish, especially when it comes to sub/bass cabinets.

Now, the mirror finish, whether it's an automotive paint or clear coats over hardwood veneers, is a whole different process, but I've done my fair share of those, too.

For the cost of that double 10 you're looking at, you can make 2, maybe 3 cabinets with divers and 800watt servo amps. Once again, the finish is where people get picky.

Fruit for though, ay?

Best regards

You make it sound so easy. I sure wish you were my neighbour!

 

[levimax]

You make it sound so easy. I sure wish you were my neighbour!

I have recently built 2 subs from flat packs from GSG which were CNC machined and they went together nicely and the joints and bracing are so tight that with a little glue it is not hard to get a good seal. All the round overs are cut and every precision details (like doubling or tripling up the front baffle) have precision cut holes and dowels to keep everything lined up while glueing and clamping. Everything is thought out and detailed in the instructions. While I have worked with and have owned saws and routers throughout my life I could not begin to make anything like what I built from the kit even though I know it is technically possible. I agree with what @OldHvyMec says except he needs to qualify it with "if you are a skilled and experienced craftsman" which I am sure he is. For me putting the kit together without incident was still a decent enough challenge and I just went for the "textured black" finish which was still hard for me but nothing like a "real" veneer finish. If you decide to go the with G22 I would definitely have the MDF or Plywood machined and possibly even assembled and finished by one of the companies listed up thread. Enjoy which ever way you decide to go.

 

[kemmler3D]

Thanks. This was a very balanced and thoughtful reply by someone who sounds like he knows what he is talking about.

Truthfully I don't trust myself to disassemble and put a sub back together and not screw something up, or not have things tight enough, or get the measurements wrong etc. Which is might seem strange because I have taken apart and put back together many computers / laptops.

In my opinion the G22 was one of the best subs for music ever made. Direct servo, dual opposing, not too big, dug down to 14 Hz. I just don't feel comfortable building one. If two were for sale id jump on it. If i knew used ones came up for sale often i'd also go the G22 route. I could be waiting years for a used one, and if one did came for sale, would the person be willing to ship?

The Sigberg 10D is also dual opposing and also draws little power which I need for my old wiring, and contains audiophile amps and drivers. It's just it's an expensive small niche sub. I will figure what I will do soon.

I would say if you have any woodworking experience beyond putting together IKEA furniture you shouldn't be intimidated, just ready to work very deliberately so the measurements all come out right. There are probably hundreds of threads between here and DIYAudio showing how people put speakers (including subs) together, so if you need inspiration or guidance, there is no shortage.

Also, if you find a cabinet shop that's willing to take this on, there's a reasonable chance they'll actually glue everything up for you too... (for a price) in which case you just have to screw the drivers and amps into place. While I understand it feels like high stakes, if you can seat a CPU without bending pins, you're more than ready to drop a sub driver into a pre-cut hole.