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That escalated quickly!

Which Danleys are those?

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How big is the risk of skram dancing around in a high powered club situation? They have bigger piston area/sqft of cab volume compared to my keystrones, which move around on all floors I've tried them on if nothing significantly weighty is strapped onto them.

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1 hour ago, Ricci said:

That escalated quickly!

Which Danleys are those?

Looks like the SH50..

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Yes, it's a Danley SH50. Still my go to speaker for accuracy/dynamics after all the years I've owned it.

@m-ms I haven't compared the Skhorn/Skrams yet. I just have all 3 going at the same time and it's quite an upgrade from a single skhorn. Crazy hard-hitting dynamics with all 4-21's going, like a sledgehammer hitting the chest. 

It's a little scary with an FP20K on tap, have to exercise some caution or I'll start cracking/walls and breaking wife's stuff 🤯

 

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On 5/27/2019 at 3:13 AM, m_ms said:

Have you done any comparisons between the two Skrams and the single SKhorn, I mean simply by listening to them? 

I wouldn't expect such comparison to be meaningful because the sound will depend a lot on each sub's location in that (presumably) small room.

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2 hours ago, SME said:

I wouldn't expect such comparison to be meaningful because the sound will depend a lot on each sub's location in that (presumably) small room.

I believe you've made your point (i.e.: referring to your (earlier) multiplied post) ;)

Seriously, you may be right. Maybe what I should wait for are some measurements to see how the Skrams "behave" compared to the SKhorn. 

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Yes it's a small room, I wish it was bigger. Agreed I'm nowhere near maxing it out to do a "meaningful" test. I'm liking the distributed sub approach though and I'm not going to have the skrams powered to have it jumping around. With that said, for home use 2 Skrams will be better than one Skhorn. IMHO

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27 minutes ago, Jesal said:

Yes it's a small room, I wish it was bigger. Agreed I'm nowhere near maxing it out to do a "meaningful" test. I'm liking the distributed sub approach though and I'm not going to have the skrams powered to have it jumping around. With that said, for home use 2 Skrams will be better than one Skhorn. IMHO

I would expect that too. How low would you estimate they go, honestly - 25Hz? What drivers are you using - the B&C 21WS152, 21DS115, or..? Your "avatar" pic would seem to suggest the B&C 21DS115..

Btw, do you have any of the ports blocked (oh well, not according to the picture you supplied)?

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Yes, it's loaded with 21DS115s. I don't think it does 25hz the way I have it setup with all ports open.

But it's for music only right now so I don't miss it, but I have so much headroom that I can plug ports and go under 20Hz when I get my HT going.

Just loving the extra headroom. I have an extra Skram box in my garage planned for nearfield.

But... although the wife is patient with all this, another BigA$$ NF sub is pushing it LOL

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Would there be big gains by doing 1 or 2?

Or are both options pretty much 1/8 space corner loading?

 

 

Skram.thumb.jpg.540bffcb5bc1ed9981bcf87f7779a8cd.jpg

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22 minutes ago, Jesal said:

Would there be big gains by doing 1 or 2?

Or are both options pretty much 1/8 space corner loading?

Facing the corner should be a little bit smoother through the crossover region >80Hz. Other than that experimentation and measurements would give the best answers.

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20 hours ago, m_ms said:

I would expect that too. How low would you estimate they go, honestly - 25Hz?

In a home sized space they should do well to 25Hz with all vents open. Should only be roughly 6dB down outdoors at 25Hz. In room will probably boost it back up a little.

Double Skram should have a little bit extra on a single Skhorn at the limit, assuming both are using the same drivers.

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Ok thanks Josh, wasn't sure if I would gain 3dB over facing out option.

I can move it around and experiment, lucky the Skrams are so much easier to move around than the Skhorn :)

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1 hour ago, Ricci said:

In a home sized space they should do well to 25Hz with all vents open. Should only be roughly 6dB down outdoors at 25Hz. In room will probably boost it back up a little.

Double Skram should have a little bit extra on a single Skhorn at the limit, assuming both are using the same drivers.

That's very decent extension from a box of this (relatively) moderate size, housing a 21" driver, and sporting a sensitivity in the late 90's or around 100dB's? Impressive engineering/design, Mr. Ricci.

If blocking one of the 4 vents, would honest 20Hz or even slightly lower be achievable in-room? Continuing, will port noise with 3 open vents be a non issue below 120-125dB's (or even higher), with a pair of Skrams?

Any preference between drivers such as the B&C 21DS115, Lavoce SAN214.50 and RCF LF21N551? Here in Europe the B&C 21DS115 comes some 50 Euros cheaper compared to the other two alternatives, but overall performance seems comparable. Being even more expensive than either of those drivers, would there be any uptick in using the B&C 21SW152? The IPAL I'm sure will add a few dB's more output. 

(EDIT: effectively you did answer above question earlier in this thread:)
 

Quote

21SW152-4 models great in this cab. It's one of the smoother modeling drivers in it. All of the usual pro 21's should be a good match. 18Sound 21ID, 21NLW9601, B&C 21DS115, 21SW152, 21Ipal, RCF LF21N551 looks decent, Lavoce SAN214.50 and the new Eminence NSW6021-6. 

If one were to compare a single Skram with a single MicroWrecker tapped horn (with a 15" B&C), how would that go about? The Skram I'm sure will have perhaps some 10dB's extra output from, say, 30 or 35Hz to 100Hz, but will it feel more visceral at the same SPL? A 21" driver has roughly twice the radiation area of a 15" unit, but the 15" driver in the MW is fully horn loaded (i.e.: as a tapped horn at least), whereas the 21" in the Skram isn't (it seems there's a slight horn-loading in the Skram?). That is to say: the force multiplier via the horn-loading of the 15" in the MW is bigger than any such of the 21" in the Skram. At least this would make a comparison on a driver-to-driver basis difficult, I'd say. Sorry for this speculative question - I'm just curious..

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20 minutes ago, m_ms said:

That's very decent extension from a box of this (relatively) moderate size, housing a 21" driver, and sporting a sensitivity in the late 90's or around 100dB's? Impressive engineering/design, Mr. Ricci.

If blocking one of the 4 vents, would honest 20Hz or even slightly lower be achievable in-room? Continuing, will port noise with 3 open vents be a non issue below 120-125dB's (or even higher), with a pair of Skrams?

Any preference between drivers such as the B&C 21DS115, Lavoce SAN214.50 and RCF LF21N551? Here in Europe the B&C 21DS115 comes some 50 Euros cheaper compared to the other two alternatives, but overall performance seems comparable. Being even more expensive than either of those drivers, would there be any uptick in using the B&C 21SW152? The IPAL I'm sure will add a few dB's more output. 

If one were to compare a single Skram with a single MicroWrecker tapped horn (with a 15" B&C), how would that go about? The Skram I'm sure will have perhaps some 10dB's extra output from, say, 30 or 35Hz to 100Hz, but will it feel more visceral at the same SPL? A 21" driver has roughly twice the radiation area of a 15" unit, but the 15" driver in the MW is fully horn loaded (i.e.: as a tapped horn at least), whereas the 21" in the Skram isn't (it seems there's a slight horn-loading in the Skram?). That is to say: the force multiplier via the horn-loading of the 15" in the MW is bigger than any such of the 21" in the Skram. At least this would make a comparison on a driver-to-driver basis difficult, I'd say. Sorry for this speculative question - I'm just curious..

Skram has 4 vents. Each is equivalent to a 6" round port. With 1 vent blocked and 3 open you have the equivalent of three 6" vents still operating. Tuning drops to about 24.5Hz. There should still be a lot of headroom down to 20Hz in room. 2 vents open is 20Hz tuning, etc...

21DS115 is a good match if it is the cheapest option.

I can't really answer about the MW comparison. I've never heard one or modeled them so I'd rather not speculate.

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16 hours ago, Ricci said:

Skram has 4 vents. Each is equivalent to a 6" round port. With 1 vent blocked and 3 open you have the equivalent of three 6" vents still operating. Tuning drops to about 24.5Hz. There should still be a lot of headroom down to 20Hz in room. 2 vents open is 20Hz tuning, etc...

21DS115 is a good match if it is the cheapest option.

I can't really answer about the MW comparison. I've never heard one or modeled them so I'd rather not speculate.

So no port noise - I guess that figures given the stated venting area, but just wanted to be sure. Air velocity I take it can be quite violent through the ports with designs as capable as this, and with longer-throw 21" drivers that can shift a lot of air. 

I'd assume your answer re: the speculative question on a comparison between the MW and Skram. My guess is the Skram will be even more visceral-sounding than the MW, and with a single blocked port go almost as deep. I'm extremely happy with my MW's though, and with a 7th order (8th order alternatively) low-pass at 80Hz they're no audible effects of any higher band anomalies. They could possibly be crossed higher if it weren't for the sidewall placement but instead flanking the mains (in a bigger room). The Skram seems to be able to low-pass without issues at 100Hz or even above, with the potential advantages that follows here, so with its other likely traits that certainly makes it a serious contender for a future build. A main concern of mine is integration with the mains. The MW's integrate, for all I'm able to assess, more or less perfectly with my mains, certainly not something I'd want to miss out on.. 

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Is there any requirement or acoustical impact to not having the holes in the upper front port braces?  I assumed it was purely for weight savings, but I wanted to be sure before I put the last side on mine without holes.

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3 hours ago, zolthoff said:

Is there any requirement or acoustical impact to not having the holes in the upper front port braces?  I assumed it was purely for weight savings, but I wanted to be sure before I put the last side on mine without holes.

I've asked this same question a page back

DSL1 commented that it's just for weight savings. I found it a pain to drill holes with hole saws/or circle cutters so I went without it on my Skrams/Skhorns

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53 minutes ago, Jesal said:

I've asked this same question a page back

DSL1 commented that it's just for weight savings. I found it a pain to drill holes with hole saws/or circle cutters so I went without it on my Skrams/Skhorns

Thanks.  I think I had seen that.  I just wanted to be sure that there wasn't anything different for the ones in the mouth of the "horn".  

I hear ya on the pain with the hole saw.  I did a bunch on the inside, but since I wanted the front to look a bit prettier, I didn't want my dull hole saws ugly-ing up the finish of the birch. 

Based on the fact that it looks like you have several of these done now, I think I'll copy you on the no holes method!

It'll stay in place extra nicely with that added weight 😉

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Followup build question - if going for a single port block, is there any benefit to blocking a particular port over another?  As in - only do an edge or a middle one might be fine too?

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There may be a tiny difference between the outer vents and the center ones due to oroximity to the side wall, but I'd have to measure it. Go with whatever works for you. It shouldn't made a difference. 

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Wood for 4 Skrams acquired.  I am looking at dampening materials for the low tune chamber. Seen most people using the egg carton shaped foam panels, is that the best bet? I suppose those foam panels come in various qualities, where are people sourcing it from?  

EE461341-383B-4E5E-A2C2-D40D9810393C.jpeg

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Looking good Zolthoff, how many Skrams are you building?

I might build 2 more, my wife noticed I'm bored and asked me

"Why don't you build something" Ok you don't have to twist my arm lol

I can probably stack two more on top of the SH50 ;)

 

Skram5.jpg

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Well I'm tempted to build another, but I think I need to soundproof my theater more first.  It is a basement room in a 3000+ sq ft house, but I think there's no room you can go to escape just the one.  

How in the world is your house intact with what you've got so far,  Jesal?  

On the plus side, it was pushing 90 degrees in Iowa today so sitting in front of the Skram vents with the Edge of Tomorrow intro was a nice way to keep cool :)

Single port block seems to be working nicely.  I was figuring with the side wall loading, the one I blocked would be a touch lower tuning than blocking an edge one

Probably gonna grab some measurements on Monday. 

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