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Ricci's Skram Subwoofer & Files


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Hi all,
After 2 years of having a SKRAM build on my radar, I'm finally nearing the end of the construction phase of my first (of hopefully 6 someday). This is my first cabinet build with an access hatch, and my plan for attaching the hatch to the rear panel was to use threaded inserts. The engineering part of my brain wants to love threaded inserts, but after many failed attempts with them - including just now on this build - I've learned that without either a CNC, or a drill press and a laser interferometer, they're basically impossible to line up straight enough by hand to be useable. Is it common to just run plain old deck/wood screws to attach an access hatch? I'm not expecting to be inside the cabinet often (hopefully never) but a bit nervous about threads blowing out after a couple times taking hatch on/off. 

IMG_0830.jpeg

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8 hours ago, btwhite92 said:

Hi all,
After 2 years of having a SKRAM build on my radar, I'm finally nearing the end of the construction phase of my first (of hopefully 6 someday). This is my first cabinet build with an access hatch, and my plan for attaching the hatch to the rear panel was to use threaded inserts. The engineering part of my brain wants to love threaded inserts, but after many failed attempts with them - including just now on this build - I've learned that without either a CNC, or a drill press and a laser interferometer, they're basically impossible to line up straight enough by hand to be useable. Is it common to just run plain old deck/wood screws to attach an access hatch? I'm not expecting to be inside the cabinet often (hopefully never) but a bit nervous about threads blowing out after a couple times taking hatch on/off. 

IMG_0830.jpeg

The two most important things here are the type of threaded inserts you use and the accuracy/size of the hole you make. For hatches I use M6 bolts and the hole for the threaded insert is a 7.5mm. The holes are drilled on my cnc with cnc drills, producing an exact 7.5mm bore, which will guide the insert perfectly so it's 'pull' itself straight simply because it doesn't have room to sit at an angle. If you drill holes by hand, a lot of factors have an impact on the actual bore size you end up with, so I'd recommend testing different drill sizes on some scrap material and measuring the actual bore, so you get that right. You might find out you need a 6.5mm drill to make a 7.5mm hole (holes turn out 1mm larger, if the drill tip if offset by 0.5mm for example).

I've tried out just about all types of threaded inserts I could find and these are imo by far the best ones:

set-of-50-threaded-inserts-screw-in-nuts-m4x10-mm.webp.20c2db841ec43be478d5ebd5b8ff11b4.webp

They grip the wood much better than anything else I've tested.

I use this Makita to install the inserts:

DWR180_C2L0.jpg.60ae02e4987cc5f65a89fec3a346ca69.jpg

 

For the through-holes on the other panel I drill holes 1mm oversized.

IMG_8041.thumb.jpg.90217e1387534d8d1ad0fc703d912961.jpg

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14 hours ago, btwhite92 said:

Hi all,
After 2 years of having a SKRAM build on my radar, I'm finally nearing the end of the construction phase of my first (of hopefully 6 someday). This is my first cabinet build with an access hatch, and my plan for attaching the hatch to the rear panel was to use threaded inserts. The engineering part of my brain wants to love threaded inserts, but after many failed attempts with them - including just now on this build - I've learned that without either a CNC, or a drill press and a laser interferometer, they're basically impossible to line up straight enough by hand to be useable. Is it common to just run plain old deck/wood screws to attach an access hatch? I'm not expecting to be inside the cabinet often (hopefully never) but a bit nervous about threads blowing out after a couple times taking hatch on/off. 

 

I'd add speaker gasket with screws or threaded inserts. I used my CNC and still managed to have a few inserts and bolts not lined up perfectly (my fault, not the machine's). 

Wood screws, with the right temperament will work just fine. Like you said, you shouldn't need to get in there much (or hopefully ever again). 

 

Edit: BTW - looking great so far. 

 

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Finally I can post some news about "my" skram N°. 3 and 4. 

Although we love our first 2, we decided to change the design for the new ones, replacing the acryl front with a layered front with 12mm mpx,  12mm Fenix compact plate and 1mm brass inbetween. The pattern in the fenix plate should represent dry, splitting earth, witch turnes out... maybe not close enough to get it, but still looking cool

Also, we stopped making those fancy carbon layered mapple plates, resulting in maybe 10-15% more weight but a hole a** less work haha

We also built a trailer for our sound system, towed by an eletric tuk-tuk, resulting in an approx. 1000kg sound bike

Next week we will take our Tuktuk for a ride on the vienna Pride demonstration 

IMG_0760.jpeg

IMG_0012.jpeg

IMG_0554.jpeg

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The 4 skrams are all loaded with B&C ipals and each one is powered and processed by an ipalmod. We were lucky and bought everything more than a year ago, so prices were more than 30% less than today

 

The tops are 2 beyma 12mc700nd in a closed box paired with a mundorf pro AMT. We are missing a little kickbass, hopefully we find time to build a pir of PM Tops soon.

Tops are driven by a labgruppen fp1000 and processed by a bss soundweb dsp

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Hey all

In a bit of a crisis here so sorry for the sense of urgency. Would really appreciate insight from cabinet designers in particular. 

I’m assembling a couple of skrams and a friend brought up a concern regarding a modification I did to the vent panel (component H) which has basically put the build to a complete stop… Was hoping someone could advise whether the mod is significant enough to be audible and whether I should abandon the idea entirely. 

I reduced the depth of component H by 1-3/4” purely for aesthetic reasons. See attached pictures. The vent panel would end at the correct spot on the hatch side but be short on the front. I did not realize that this would reduce the horn length and the vent length.

The vent dividers (component I) and mouth braces (component R) painted black in the pictures were also modified in the same way, but I figured that’s a non issue as that’s just bracing. 

Would greatly appreciate everyone's advice here so I can keep the build moving. Thank you
 

image_50404353.JPG

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  • 3 weeks later...
On 5/26/2024 at 8:50 AM, peniku8 said:

 

I've tried out just about all types of threaded inserts I could find and these are imo by far the best ones:

set-of-50-threaded-inserts-screw-in-nuts-m4x10-mm.webp.20c2db841ec43be478d5ebd5b8ff11b4.webp

They grip the wood much better than anything else I've tested.

I use this Makita to install the inserts:

 

 

For the through-holes on the other panel I drill holes 1mm oversized.

 

Where do you get those ?

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On 6/21/2024 at 8:54 PM, rolo95 said:

I think its pretty well known that the chinese amps deliver when it comes to power, but you don't buy Powersoft just for the power, you buy it for the great dsp that lets you run your subs way harder while knowing you won't burn the VCs. Running subs without the true power limiter (or something similar from another manufacturer) is just leaving headroom on the table. I run my subs very conservatively right now and I'm sure that they'll gain a few dBs just from being able to replace the (unfit) RMS limiter with a 150ms attack time that's currently holding them back with the true power limiter, aside from the upgrade in output power.

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  • 2 weeks later...
On 5/26/2024 at 8:50 AM, peniku8 said:

The two most important things here are the type of threaded inserts you use and the accuracy/size of the hole you make. For hatches I use M6 bolts and the hole for the threaded insert is a 7.5mm. The holes are drilled on my cnc with cnc drills, producing an exact 7.5mm bore, which will guide the insert perfectly so it's 'pull' itself straight simply because it doesn't have room to sit at an angle. If you drill holes by hand, a lot of factors have an impact on the actual bore size you end up with, so I'd recommend testing different drill sizes on some scrap material and measuring the actual bore, so you get that right. You might find out you need a 6.5mm drill to make a 7.5mm hole (holes turn out 1mm larger, if the drill tip if offset by 0.5mm for example).

I've tried out just about all types of threaded inserts I could find and these are imo by far the best ones:

set-of-50-threaded-inserts-screw-in-nuts-m4x10-mm.webp.20c2db841ec43be478d5ebd5b8ff11b4.webp

They grip the wood much better than anything else I've tested.

 

 

Hey Peniku,

and what you use for the 8 holes to attach the drivers to the baffle

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2 hours ago, rolo95 said:

Hey Peniku,

and what you use for the 8 holes to attach the drivers to the baffle

The same. I use them for drivers, casters, the hatch and over hardware, like an M20 pole plate.

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10 hours ago, rolo95 said:

that's the one that expands right the PL 3x ?

so you use that trough all the cabinet

 

"Pl premium" is the product name. It has a 3x on it for marketing: https://www.loctiteproducts.com/products/central-pdp.html/loctite-pl-premium/SAP_0201CRL029Q4.html

I use Pl premium with clamps and zero nails or screws on all the joints and seams. The wood will fail before the PL premium. 

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9 hours ago, klipsch said:

The wood will fail before the PL premium. 

Just as it will with regular wood glue. PL is great when your cuts are rough and you need the glue to fill gaps to prevent possible air leaks. If you have nice clean cuts and dados, then wood glue >>> PL, since it's easier to work with. PL being very viscous means it doesn't spread nearly as well and you need high and consistently distributed clamping force (clamps directly on the material will not work!). Just make sure you have the water resistant wood glue and you're good. I paid 50 bucks for my 10kg (22lbs) bucket, which is probably enough for several dozen speakers.

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  • 2 weeks later...

After switching to Powersoft from lab clones/china dsp I never wanna go back again... These limiters are to die for..! The subs sound so much better now with some proper limiting structure.. and they go much louder without having to fear of blowing out expensive drivers.

3wGWTVX1.thumb.jpeg.b80dde43a1dd91cdaf77d0f19d26a9ff.jpeg

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10 hours ago, peniku8 said:

After switching to Powersoft from lab clones/china dsp I never wanna go back again... These limiters are to die for..! The subs sound so much better now with some proper limiting structure.. and they go much louder without having to fear of blowing out expensive drivers.

3wGWTVX1.thumb.jpeg.b80dde43a1dd91cdaf77d0f19d26a9ff.jpeg

Which amps did you start with and go to?

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On 7/20/2024 at 10:54 AM, chrapladm said:

Which amps did you start with and go to?

We had a Sanway DP10Q before (which I added balanced post-dsp outputs to, so we could add our FP-13000 while on the same processing for more subs).
The amps are well-built and do output good power, but as we know, they have no protection circuitry and the dsp is just.. "basic". You get 8 points of PEQ, adjustable Xovers and an unpredictable limiter that doesn't work well.
It's just one peak limiter, so you have no way of protecting your speakers against thermal overload.
On top of that, the amp's inputs clipping point is 12dBu, so I had to build 12dB pad XLR cables to avoid overloading the inputs with the mixing console. Then the channels have a maximum gain that's way too low. As soon as you use substractive EQ points, you won't be able to hit maximum output levels anymore, so I had to sacrifice one PEQ point per channel to make it a 20Hz High Shelf as makeshift gain control. Atrocious, really.

Now my company bought a sample of a Powersoft OEM-only amp which I'll be using as development platform for my own speaker designs, so I can bundle system amps with the speakers, like the big manufacturers do. It's coming with us for field-testing and after setting up dsp profiles this week, the first show with it will be next week.
It's basically an X4 with less 2R power. 4x3KW into 4R. 2U, touchscreen. We also bought M-Force and the M-Drive is a great amplifier too, of course.

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