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Ricci's Skram Subwoofer & Files

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Brian,

Not yet...This is the first design I ever posted prior to doing a GP workup. It'll get there eventually. I don't even have cabs yet and I think it's approaching 10 people who've already built them. Comparisons to vented have been discussed a lot. I'd suggest reading through the Skhorn thread, the M.A.U.L. thread and this one from the beginning. My reasons for using these style of cabs go a little bit beyond simple sensitivity and output gains. The short version is it buries some of the operational junk from a direct radiator in the cab and gets a few more dB before the sound audibly degrades. 

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If you're looking for a vented cabinet with 30 Hz tune and same driver(s), you can build the cabinet quite a bit smaller and get almost as much performance at the tune.  Above 30 Hz however the Skram will still have at least a few dB edge and the benefit of acoustic low pass filtering.  Larger cabinets don't seem to gain much more, at least with the 21DS115.  The motor is crazy strong.

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On 6/24/2019 at 5:16 PM, Ricci said:

What driver would you be using?

#2. I'm not sure I understand what you are asking? The Skhorn is 54"x32"x24". The front face is 54"x24". It can either be 54" high which would be typical arrangement, or 24" high and 54" wide. The Skram is 36"x32"x24". The front face is 36"x24". Usually it would be 36" high and 24" wide. Either cab can be arranged either way depending on the needs and amount of cabs.

PA situations is really what these are meant for first and foremost.

You mentioned in your first post here, that it would be possible to make the Skram as if it would be really the Skhorn cut in half. The Skram is a little bit bigger than half the Skhorn.

 

Driver would be anything but the IPAL, I can justify the costs off almost all drivers, but not the IPAL. I would however like to model the driver's in hornresp if possible. Do you have the respective specs for the different port configurations? 

And yes, I know it's pa oriented, just like a Danley synergy is, doesn't make it a bad home theatre sub/speaker ;) just build enough and use them with the lowest tuning frequency. Definitely when corner loaded.

 

 

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Looking at options for foam to line the chamber behind the driver.  Is there something specific I should be looking for? Or will any egg carton style foam work? Seeing some options on amazon for reasonable prices, or should I look at something from a more reputable source?

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Second cab almost done, 2 more to go. These go together pretty quick, considerably faster than othorns. Taking me about 4-5 hours per cab to assemble.   

2D678569-9F39-44CF-8A0B-9BE48AB55987.jpeg

95B9714E-42D5-4069-BBDB-788CD860A03B.jpeg

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Cabs look great Jay. 4 Skrams should be enough. 😉

I should have done all 4 in one shot, getting lazy, now the last two are taking a lot longer...

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Thanks. Honestly seeing your set up with the sh50’s inspired me to level up haha.  I’ve got a pair of sh46’s on the way.  Mind you this won’t be in my living room, 4 skrams and the danleys should be a pretty potent combo for our studio 

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9 hours ago, Leimahmood said:

are those skram are good in movies with 21ds115 4ohm driver

I suspect the Skrams are as good for movies with the B&C 21DS115-4 as any other fitting driver 21" driver in this cab, the variable here being the number of ports being blocked and how this affects extension. I'm guessing, but for movie playback (and music playback in general) it seems a good compromise is blocking one of the four ports for a reasonable balance between extension and output/response smoothness in the lower octaves.   

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16 hours ago, Leimahmood said:

are those skram are good in movies with 21ds115 4ohm driver

Depends on what you’re looking for.  I’ve measured my 24s in many rooms and they’re flat to 7 Hz in-room with over reference level output.  The 21s won’t achieve that in a Skram but they’ll run away from my 24s above 25Hz I’m sure.  Some don’t worry about under 20Hz content while I will never go back to subs that can’t provide solid 10 Hz output.  So it really depends on what you want and your circumstances.  If you’re on concrete and can’t put down wood, you won’t get as much tactility so it may not be worth chasing under 20Hz.  But if you’re on a wood floor, the deep bass imparts some really nice tactility through the floor during movie explosions.  Also depends on the size of the room you’re trying to cover and number of Skrams you’re building.  4 Skrams in a small room like some seem to be doing will probably have quite a bit of under 20 Hz output but would have so much headroom above 30 Hz that wouldn’t get used if under 20 Hz is the goal.  So just depends on the goals as there are many, many ways to get there.

 

One other thing to note is I recommend multiple “lesser” subs (18s instead of 24s::)) in a room to get more even bass.  If you have a sub, turn 1 (only 1) on and walk around the room while playing.  You’ll hear some areas, especially the corners, where the bass is stronger and maybe boomy while other areas don’t have as much bass.  This is your room interacting with the bass waves.  To combat this, Harman did extensive testing and found 4 subs placed in the 4 center walls of the room was about the best (diminishing return over 4 subs) followed closely by 4 subs in the corners.  So if you’re only planning 1 uber sub, I’d strongly suggest against that and to go with multiples so you’ll get more even bass.  Note that long rectangular rooms may need a couple of fill subs though room simulation software would need to be used to identify this.

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7 hours ago, dgage said:

Depends on what you’re looking for.  I’ve measured my 24s in many rooms and they’re flat to 7 Hz in-room with over reference level output.  The 21s won’t achieve that in a Skram but they’ll run away from my 24s above 25Hz I’m sure.  Some don’t worry about under 20Hz content while I will never go back to subs that can’t provide solid 10 Hz output.  So it really depends on what you want and your circumstances.  If you’re on concrete and can’t put down wood, you won’t get as much tactility so it may not be worth chasing under 20Hz.  But if you’re on a wood floor, the deep bass imparts some really nice tactility through the floor during movie explosions.  Also depends on the size of the room you’re trying to cover and number of Skrams you’re building.  4 Skrams in a small room like some seem to be doing will probably have quite a bit of under 20 Hz output but would have so much headroom above 30 Hz that wouldn’t get used if under 20 Hz is the goal.  So just depends on the goals as there are many, many ways to get there.

 

One other thing to note is I recommend multiple “lesser” subs (18s instead of 24s::)) in a room to get more even bass.  If you have a sub, turn 1 (only 1) on and walk around the room while playing.  You’ll hear some areas, especially the corners, where the bass is stronger and maybe boomy while other areas don’t have as much bass.  This is your room interacting with the bass waves.  To combat this, Harman did extensive testing and found 4 subs placed in the 4 center walls of the room was about the best (diminishing return over 4 subs) followed closely by 4 subs in the corners.  So if you’re only planning 1 uber sub, I’d strongly suggest against that and to go with multiples so you’ll get more even bass.  Note that long rectangular rooms may need a couple of fill subs though room simulation software would need to be used to identify this.

well i m not ture 20hz lover

i need good punchy bass

recently i make a box its 18cubic feet 16hz tune it good around 15 to 70hz but after that its show lack mid basses like from 80 to 120

so that y my eyes on skram and i have a pair of 21ds115 4ohm

room is 13.5feet wide x15.5 lengthy x8high and fully seal room no window etc

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Why don’t you look into a dedicated midbass instead of using a subwoofer to play that high?

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I posted the possible vent tunings with these a few pages back. With 1 vent open it should be around 14Hz. In a room for HT, with a lot less overall headroom needed than for PA work this might be the ticket. I think 2 vents open was going to be about 19Hz.

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1 hour ago, Ricci said:

I posted the possible vent tunings with these a few pages back. With 1 vent open it should be around 14Hz. In a room for HT, with a lot less overall headroom needed than for PA work this might be the ticket. I think 2 vents open was going to be about 19Hz.

Wow.  That would definitely get down into the single digits with 1 vent open.  Nice.  Any issues with port velocity with only 1 vent open?

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3 hours ago, Ricci said:

I posted the possible vent tunings with these a few pages back. With 1 vent open it should be around 14Hz. In a room for HT, with a lot less overall headroom needed than for PA work this might be the ticket. I think 2 vents open was going to be about 19Hz.

well ricci my main need is 30hz and up to 120hz i need tiet punchy basses for ultra low i use an other subs drivers

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31 minutes ago, Leimahmood said:

well ricci my main need is 30hz and up to 120hz i need tiet punchy basses for ultra low i use an other subs drivers

The Skram would definitely give you some chest pounding bass but I’d still suggest considering dedicated midbasses to give you control over the entirety of midbass from 60-200/300.  Even though my subs play up to 200 Hz, I built some midbass units based on the JBL 2226 drivers and I was very happy I did.  This lets my subs play more in their sweet spot as well as keep their directionality out of it while being able to dial in as much midbass as I want.  You mention you have other sub drivers for deep bass, I assume they should be able to play up to 60 Hz so the Skram almost seems like you wouldn’t need/use its full capabilities anyway.  And the Skram, while smaller than Ricci’s other offerings, isn’t exactly a small enclosure, so you’re putting some big units in to play a fairly narrow band of the frequency range.  The Skram would definitely be fun and maybe you just want to play with it but based on the limited info, I’m not sure you’d get the most out of it with your current configuration but then again, configurations change.  Maybe you build the Skram and decide you don’t need the subs currently playing deeper.  Playing with equipment (options) is sometimes as much fun as playing the equipment. :)

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18 hours ago, Leimahmood said:

well ricci my main need is 30hz and up to 120hz i need tiet punchy basses for ultra low i use an other subs drivers

So, in the case of your initial and specific request aimed at the Skrams it's not really about movie playback capabilities as such (a different inquiry altogether, it would seem), but simply whether they kick a** from 30-120Hz with a suggested (and, it seems, fitting) driver, the B&C 21DS115-4. From what I'm able to assess the Skrams do exactly that; being 25-120Hz monsters at a relatively modest physical size, not least in light of them being fitted with a 21" driver, close to or more than 100dB sensitivity and hitting 25Hz quite comfortably. For your purpose I'd leave all ports open, or close no more than one per cab. Traits on paper that, if it weren't for my MW's, I'd have a pair build to my own setup in a heartbeat. 

EDIT: more fittingly you may consider poster @dgage's advice of either not being in the need of the Skrams, or use them solely with, say, 2 ports open. Personally I'd go with the latter option :) 

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9 hours ago, m_ms said:

So, in the case of your initial and specific request aimed at the Skrams it's not really about movie playback capabilities as such (a different inquiry altogether, it would seem), but simply whether they kick a** from 30-120Hz with a suggested (and, it seems, fitting) driver, the B&C 21DS115-4. From what I'm able to assess the Skrams do exactly that; being 25-120Hz monsters at a relatively modest physical size, not least in light of them being fitted with a 21" driver, close to or more than 100dB sensitivity and hitting 25Hz quite comfortably. For your purpose I'd leave all ports open, or close no more than one per cab. Traits on paper that, if it weren't for my MW's, I'd have a pair build to my own setup in a heartbeat. 

EDIT: more fittingly I may consider poster @dgage's advice of either not being in the need of the Skrams, or use them solely with, say, 2 ports open. Personally I'd go with the latter option 

if i make a mbm type box iss it fine

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Hello !

Does someone expect to measure a Skram soon ? :)
I aim to build 2 Othorns in August but maybe a Skram could be an alternative.

I saw the Ricci's simulations but @m_ms talks about 100dB sensitivity where the sims shows 97dB.

I'm looking for the best output between 25hz and 70hz, should I go for two Othorns or two Skrams ?

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1 hour ago, Alexlel said:

Hello !

Does someone expect to measure a Skram soon ? :)
I aim to build 2 Othorns in August but maybe a Skram could be an alternative.

I saw the Ricci's simulations but @m_ms talks about 100dB sensitivity where the sims shows 97dB.

I'm looking for the best output between 25hz and 70hz, should I go for an Othorn or a Skram ?

My assessment of the Skrams-sensitivity was with a pair of them in mind (like, emulating a single SKhorn), so that would have them hover in the 100dB territory. Sorry I wasn't clear about that. 

Really, I'm a blundering novice on these matters, so @Ricci and others would be much better fitted to answer your questions, but I've also had my thoughts on the Othorn vs. Skrams and what to choose here if one were to venture in that direction (I'm very happy with my pair of MicroWrecker tapped horns of @lilmike, but am intrigued nonetheless).

Initially I got the crazy idea (but still relevant, I believe) that since my main speakers are all-horns it's better to use a horn variety to augment them below 80 or so Hz instead of using direct radiators (hence my choice of the MW's), but with the Skrams I'd be willing to make an exception (i.e.: hidden driver, a very slight horn-loading(?) of the front side of the driver-cone; ported on the backside, a bad-ass 21" driver w/massive power handling, high-ish sensitivity, relatively wide and clean bandwidth). If I'm not incorrect the Othorn is build around the B&C 21SW152, and therefore it's perhaps the best choice (apart from the IPAL) compared to other, cheaper alternatives.

The Skrams however appear to be very well equipped with the cheaper B&C 21DS115 (or other), is a less complex build (from what I've read), perhaps a cleaner upper band performance, a slightly smaller footprint, and optional lower-band extension via port blocking. It would be most illuminating listening to them side-by-side, but Ricci already elaborated on a comparison of the SKhorn vs. Othorn, which should give one an idea in regards to the Skrams vs. Othorn performance. I believe I'd go with the Skrams (a pair), but either choice I'm sure would be awesome. If you only need to go to 70Hz upwards the supposedly cleaner upper band of the Skrams may not be relevant.

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Alright, thanks for the clarification @m_ms !

Actually, I like the Skram for its design, it's an original cab compared to the Othorn which looks more like a "classic" tapped horn.
Another good point for it, is the fact that the driver is hidden, I expect to use those cabs in a sound system, I wouldn't have to be afraid of beers or malicious people.

But the Othorn is quite perfect for 25hz-70hz + it has a higher sensitivity on that band.
I think I prefer +3 dBs than a fully protected driver, otherwise you need more cabs and the cost + the building time + the logistic, make it a clear choice to me.

But who knows, maybe with real life measurements, the Skram will change my mind and won't be so far away !

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On 7/7/2019 at 8:34 AM, dgage said:
On 7/7/2019 at 5:41 PM, Ricci said:

I posted the possible vent tunings with these a few pages back. With 1 vent open it should be around 14Hz. In a room for HT, with a lot less overall headroom needed than for PA work this might be the ticket. I think 2 vents open was going to be about 19Hz.

here in our cuntry only mdf avilable and the size is in pic and can i make skram with this size mdf

 

 

20190708_191106.jpg

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What do you guys think the effect would be to run left right stacks in this configuration? Just considering my options for deployment. Putting my sh46’s on top of 2 subs stacked like this would get it them high enough without having to drag out scaffolding.  With the mouths off the ground would the subs not couple to the ground plane as effectively as if the mounts were on the ground?

53CF0738-FB5C-48DD-A4B7-BD49A72640BF.jpeg

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