Ricci's Skram Subwoofer & Files

[Ricci]

Nice setup Fink! Welcome to the forum. What drivers are you using in the Skrams? 

Also that Linea amp is supposed to be really good and beastly from what I hear. 

[nerdoldnerdith]

How does the efficiency of the SKRAM compare to the Devastator (25%)? I'm very new to the world of horns, but am looking at them to achieve visceral, impactful bass that I can't get with sealed designs. I think the pant-flapping, chest-destroying insanity I am trying to achieve has something to do with efficiency.

[Fink_Newton]

I have them loaded with B&C 21ds115-4's.   The soundsystem will be primarily used for small to medium sized outdoor parties where we might not always have adequate generator power so i figured the extra sensitivity of the 21ds115's might come in handy in certain cases.  Although from what I understand the 21sw152 will go aprox 2-3db louder before power compression sets in? We also considered the new Eminence drivers however they seemed like they would be even harder to power properly in order to get the most out of them.   The 44m20 amp has been absolutely incredible to use. I reckon it could power 8 Skrams in a pinch. We were using a Morin k30 before and although it had plenty of power it was extremely hard on our generators.  The Linea seems to be much more efficient and also there was a noticeable improvement in the tightness of the bass produced. The linea amp also limits it current draw to match the power source which has been super handy as well as integrating seamlessly with our Linea ASC48 in System Engineer.  Also wanted to say thanks for all your hard work and time you put in to sharing your knowledge and designs with us!  This whole project has been extremely fun and rewarding and wouldn't be possible without resources such as these.

[peniku8]

38 minutes ago, Fink_Newton said:

I have them loaded with B&C 21ds115-4's.   The soundsystem will be primarily used for small to medium sized outdoor parties where we might not always have adequate generator power so i figured the extra sensitivity of the 21ds115's might come in handy in certain cases.  Although from what I understand the 21sw152 will go aprox 2-3db louder before power compression sets in? We also considered the new Eminence drivers however they seemed like they would be even harder to power properly in order to get the most out of them.   The 44m20 amp has been absolutely incredible to use. I reckon it could power 8 Skrams in a pinch. We were using a Morin k30 before and although it had plenty of power it was extremely hard on our generators.  The Linea seems to be much more efficient and also there was a noticeable improvement in the tightness of the bass produced. The linea amp also limits it current draw to match the power source which has been super handy as well as integrating seamlessly with our Linea ASC48 in System Engineer.  Also wanted to say thanks for all your hard work and time you put in to sharing your knowledge and designs with us!  This whole project has been extremely fun and rewarding and wouldn't be possible without resources such as these.

The ds and sw are very similar in maximum output at their respective program powers. Bennett from B&C said you should only really use the sw if you need the higher power handling, otherwise it doesn't really matter which you pick so you should go for the cheaper one. Here is a hornresp of different drivers I've compared in the SKhorn

[chrapladm]

Ricci how does the SW152 or IPAL look at 15hz and 20hz in simulation?

[m_ms]

On 11/23/2021 at 7:07 AM, Fink_Newton said:

Had a pretty good outing this past weekend with our 4 Skrams and 2 Keystone subs for a 400 person event!  Skrams are running off a Linea research 44m20.  Tops are a pair of PM90 mid-highs which we just completed and powered by custom Hypex amps with a Linea Research ASC48 for sound processing .  Was extremely limited on speaker placement because of the low tents and would have liked to run the Skrams on their sides or separated them slightly to spread out the coverage.  Once we retire the keystones I think we may need to build another 2-4 Skrams to keep up with the Midhighs for bass heavy music but really impressed with the output overall!  Got a lot of good feedback regarding the sound and people really appreciate the change from the usual PK cx800 double 18 subs that have over-saturated the market on the BC west coast.

What's entailed in "people really appreciating the change" from double 18's to the Skram's? What's their feedback in more detail about any change in presentation here - is it simply about (more?) capacity, or does it come down to a perceived difference in presentation between the two box and driver types? 

@Ricci and others: Earlier this evening I was at local cinema watching 'Ghostbusters: Afterlife' (an amusing and largely successful follow-up to the '84 original), and was quite impressed by the bass impact and overall quality in the some 400 seat auditorium (with Atmos sound). Turns out their speakers are from QSC, and the subs they use are these:

https://www.qsc.com/solutions-products/loudspeakers/cinema/subwoofers/sb-series/sb-15121/

I take it the 21" driver used here is the B&C 21SW152, and I believe I've read only two of them subs are used in this auditorium, though I find it hard to believe given how much the bass shook the whole locale. 

My question here is: how would the QSC sub compare to a Skram, say, with the same driver? Does the Skram make more outright use of both its front and back wave of the cone by comparison, or are they comparable to one another in overall SPL and presentation?

[klipsch]

On 11/24/2021 at 1:51 PM, nerdoldnerdith said:

How does the efficiency of the SKRAM compare to the Devastator (25%)? I'm very new to the world of horns, but am looking at them to achieve visceral, impactful bass that I can't get with sealed designs. I think the pant-flapping, chest-destroying insanity I am trying to achieve has something to do with efficiency.

I'll take my Mother's advice since I don't have much nice to say about one of the sub designs - if you are OK with building VS buying - I'd recommend the skram which has a smaller physical size. 

[peniku8]

1 hour ago, m_ms said:

What's entailed in "people really appreciating the change" from double 18's to the Skram's? What's their feedback in more detail about any change in presentation here - is it simply about (more?) capacity, or does it come down to a perceived difference in presentation between the two box and driver types? 

@Ricci and others: Earlier this evening I was at local cinema watching 'Ghostbusters: Afterlife' (an amusing and largely successful follow-up to the '84 original), and was quite impressed by the bass impact and overall quality in the some 400 seat auditorium (with Atmos sound). Turns out their speakers are from QSC, and the subs they use are these:

https://www.qsc.com/solutions-products/loudspeakers/cinema/subwoofers/sb-series/sb-15121/

I take it the 21" driver used here is the B&C 21SW152, and I believe I've read only two of them subs are used in this auditorium, though I find it hard to believe given how much the bass shook the whole locale. 

My question here is: how would the QSC sub compare to a Skram, say, with the same driver? Does the Skram make more outright use of both its front and back wave of the cone by comparison, or are they comparable to one another in overall SPL and presentation?

The QSC sub is larger and probably has more vent area compared to the Skram (when you block Skram ports to reach the same ~25Hz(?) tuning), meaning the QSC will be louder in the sub bass. Skram is front loaded, which means it's more efficient (louder) in the mid/upper-bass region. Skram is basically a band pass, which means it also masks some distortion.
That would be the 3 main differences I guess. Skram has a rising native voltage sensitivity, while the QSC is probably pretty flat, going by my gut feeling here.

[Fink_Newton]

@m_msThe CX800 is a sub developed by PK sound  geared primarily towards electronic bass music.  They are quite popular around here in the electronic music scene as having PK on your flyer generates a decent amount of hype for these types of shows.  Now this is my own opinion based on experiences attending and throwing events on the BC West Coast but i have found they suffer from pretty bad port compression especially when pushed even reasonably hard.  The bass essentially turns into a very boomy/chuffy/distorted one note kinda deal that's meant to be more felt than heard. When run properly arrayed and at a reasonable level they can sound pretty good for dubstep and drum&bass but i have found that the Skrams sound way tighter and punchier overall especially when it comes to house/techno/trance.  Kick drums sound like actual kick drums where as on the cx800 the kick often loses its definition.  At the end of the day i think the Skrams just do a better job overall at reproducing the original program material compared to the cx800 which impart more of their PK signature sound which sacrifices musicality for a more visceral feeling.  There are many examples of ported double 18's out there that don't suffer from this type of problem, it just so happens that in our scene PK sound is used almost exclusively now a days so that's why people at the show noticed the difference in the Skrams.

[chrapladm]

Looked at making a template out of some scrap I have. I was hoping to recess the interior panels but wanted to know the depth others are recessing the panels? 1/4"/ 6mm? More?

[peniku8]

3 hours ago, chrapladm said:

Looked at making a template out of some scrap I have. I was hoping to recess the interior panels but wanted to know the depth others are recessing the panels? 1/4"/ 6mm? More?

If you're talking about the dado joints, I always make them 3mm. That way I can cut them with max feed rates on my machine without worrying about inaccuracies too much. I never felt the need to make them bigger, they're mostly for easier positioning anyways, so 3mm is just fine for that. imo it doesn't matter stability wise, unless you expect to throw the cabs off a balcony often.

[chrapladm]

On 12/31/2016 at 12:12 PM, dsl1 said:

It's done Glue is drying. Will pop in drivers tomorrow. Excited to hear it! 

 

 

 

 

http://i.imgur.com/75hiZqD.jpg?1

 

 

http://i.imgur.com/VNJ4Dhf.jpg?2

 

 

 

 

 

http://i.imgur.com/MWFzmqY.jpg?1http://i.imgur.com/NeH63Wk.jpg?1

 

 

http://i.imgur.com/vtsPO5y.jpg

 

 

 

 

 

http://i.imgur.com/4PKQ43Z.jpg

 

 

http://i.imgur.com/s7ZcQas.jpg

 

 

http://i.imgur.com/jD229yQ.jpg

 

 

17 hours ago, peniku8 said:

If you're talking about the dado joints, I always make them 3mm. That way I can cut them with max feed rates on my machine without worrying about inaccuracies too much. I never felt the need to make them bigger, they're mostly for easier positioning anyways, so 3mm is just fine for that. imo it doesn't matter stability wise, unless you expect to throw the cabs off a balcony often.

3mm?. Ok

 

I was thinking most did more than that. Here is dsI1's dado if thats what they are called. I liked how it aids in assembly. I plan to make four so I figured I could make a jig for the "dado's," to help speed things up since I dont have a CNC.

[peniku8]

On 11/30/2021 at 8:37 AM, chrapladm said:

 

3mm?. Ok

 

I was thinking most did more than that. Here is dsI1's dado if thats what they are called. I liked how it aids in assembly. I plan to make four so I figured I could make a jig for the "dado's," to help speed things up since I dont have a CNC.

I've build 20 speakers with this dado size now and I see no reason why I'd need them to be deeper.

And tbh, I don't think it's worth the hassle to make them when you don't have a CNC. You'll waste all the time you save on assembly with making the joints, possibly more.

[chrapladm]

16 hours ago, peniku8 said:

I've build 20 speakers with this dado size now and I see no reason why I'd need them to be deeper.

And tbh, I don't think it's worth the hassle to make them when you don't have a CNC. You'll waste all the time you save on assembly with making the joints, possibly more.

I will try and do the bracing with the dados in 3mm. Wont do all the panels this way. And as I said since I dont have all the plywood yet I will just make some jigs to do the dados. Will be making one for the hatch anyways. Gives me something to do for now.

[peniku8]

7 hours ago, chrapladm said:

I will try and do the bracing with the dados in 3mm. Wont do all the panels this way. And as I said since I dont have all the plywood yet I will just make some jigs to do the dados. Will be making one for the hatch anyways. Gives me something to do for now.

What bit will you be using for this? Something like here?
https://www.aliexpress.com/item/32947219454.html

[chrapladm]

Yes.

 

Although I may try and get one like above with the pair of guide bearings. 

[Ricci]

On 11/24/2021 at 1:51 PM, nerdoldnerdith said:

How does the efficiency of the SKRAM compare to the Devastator (25%)? I'm very new to the world of horns, but am looking at them to achieve visceral, impactful bass that I can't get with sealed designs. I think the pant-flapping, chest-destroying insanity I am trying to achieve has something to do with efficiency.

 

With bass size is king. 

Comparing the Skram or any other cab to another random bass cab is really not that useful...Unless the data is good for both and other factors are taken into consideration. Size, weight, cost, complexity, intended frequency bandwidth, etc...

All I know about the Dev style cabs is that they seem to have been inspired by my designs like the MAUL, Skhorn, etc...That's fine. No big deal. I was in no way the first to do this style of cabinet either. There is plenty of prior art in professional designs for sure. It is really difficult to have a genuinely new development in speakers unless it's in the digital domain. Anyway. They seem to be popular and there's a crap ton of flavors of the same basic thing. Most of them are MUCH bigger than the Skram. I have no idea how refined these are, or which one you are comparing to. Are there good quality GP measurements available? 

PK CX800 is really popular. It's just a vented sub that uses good drivers (18Sound 18NLW9601 units). Nothing ground breaking there, just solid components and design. Regular old vented still ticks a whole lot of boxes when done right. Especially if you start looking at output vs size. Vented will give maximum output at the LF corner in most scenario's, but will give up output in the rest of the frequency bandwidth against other types of designs of the same size. Output vs output I'd hesitate to speculate on too much, but if I had to guess I'd say they will be fairly close. The CX800 might win near the vent tuning depending on the port geometry and the Skram may win in the kick drum region but without measuring both at war volume it's hard to be definitive. CX800 should have more thermal handling just due to 2 drivers vs 1. This cab is bigger, heavier and more expensive than a Skram though. The biggest difference may be in the character of the sound rather than just output. Direct radiating sounds a bit more dirty generally speaking and a lot of people like that. 

People love to bench race subs but there's a whole lot more to it than output on a simulation. Hell this is part of the reason DB exists, was to show just how flawed a lot of these simulations and assumptions were. 

[m_ms]

On 12/3/2021 at 8:58 PM, Ricci said:

 

With bass size is king. 

Comparing the Skram or any other cab to another random bass cab is really not that useful...Unless the data is good for both and other factors are taken into consideration. Size, weight, cost, complexity, intended frequency bandwidth, etc...

All I know about the Dev style cabs is that they seem to have been inspired by my designs like the MAUL, Skhorn, etc...That's fine. No big deal. I was in no way the first to do this style of cabinet either. There is plenty of prior art in professional designs for sure. It is really difficult to have a genuinely new development in speakers unless it's in the digital domain. Anyway. They seem to be popular and there's a crap ton of flavors of the same basic thing. Most of them are MUCH bigger than the Skram. I have no idea how refined these are, or which one you are comparing to. Are there good quality GP measurements available? 

PK CX800 is really popular. It's just a vented sub that uses good drivers (18Sound 18NLW9601 units). Nothing ground breaking there, just solid components and design. Regular old vented still ticks a whole lot of boxes when done right. Especially if you start looking at output vs size. Vented will give maximum output at the LF corner in most scenario's, but will give up output in the rest of the frequency bandwidth against other types of designs of the same size. Output vs output I'd hesitate to speculate on too much, but if I had to guess I'd say they will be fairly close. The CX800 might win near the vent tuning depending on the port geometry and the Skram may win in the kick drum region but without measuring both at war volume it's hard to be definitive. CX800 should have more thermal handling just due to 2 drivers vs 1. This cab is bigger, heavier and more expensive than a Skram though. The biggest difference may be in the character of the sound rather than just output. Direct radiating sounds a bit more dirty generally speaking and a lot of people like that. 

People love to bench race subs but there's a whole lot more to it than output on a simulation. Hell this is part of the reason DB exists, was to show just how flawed a lot of these simulations and assumptions were. 

Thanks for this rundown, @Ricci. It occurred to me earlier that you preferred the Skram to the Othorn - why or how is that? I suppose the Skram is easier to build and mates well with a broader and cheaper range of drivers, is port tune-able, and may extend higher and more cleanly compared to the Othorn. Output-wise it would seem they're comparable, at least.  

Have you listened to the Skram in action by any chance, and if so what are your impressions subjectively speaking comparing it with your recollection of the Othorn? The latter is semi-direct radiating, and that may account for some its reported "character."

Oh well, only so much can be done speculating about these matters. I guess it's the nature of not being able to listen to them side-by-side, and so trying to get a bearing otherwise is attempted. Every indication so far is for the Skram's being "tight, punchy/impactful and very clean sounding" - and different at that compared to the more classical ported, direct radiating designs. Their native tune ~@29Hz with all ports open may feel slightly deeper perhaps with the ports situated so close to the floor, which may act as a slight extension even - as has also been suggested earlier. I gather blocking one port would be sufficient for both music and movie duties - save perhaps those cinephiles who crave infrasonics.

(Tidbit) Initially, prior to having my MicroWrecker's built, I actually favored the Othorn's, but the rather expensive 21SW152 was a deal breaker. So far though I've been very happy with the MW's. 

 

[Ricci]

On 12/4/2021 at 7:12 PM, m_ms said:

Thanks for this rundown, @Ricci.

 Every indication so far is for the Skram's being "tight, punchy/impactful and very clean sounding" 

(Tidbit) Initially, prior to having my MicroWrecker's built, I actually favored the Othorn's, but the rather expensive 21SW152 was a deal breaker. So far though I've been very happy with the MW's. 

 

I've not actually tested or listened to the Skram yet. I do have a pair of Skhorns which should sound very similar in character. I sold my Othorn's awhile back. I do prefer the Skhorn / Skram sound. To me it is slightly more clean, more flexible, easier to build, smaller and can avoid some of the resonances that show up in TH's. I spent a lot of time trying to clean these up in the Othorn design. TH's can sound very good and the Othorn was the best I've heard or seen measured. 

Every sub I design has priority #1 of low distortion, high headroom, high damping. Those aren't always complimentary goals. They aren't always easy to accomplish with high order designs either. 

As far as drivers go the best ones are expensive. Most of what I design requires them due to the priorities and attributes chosen. Any old driver will make noise in any cab but there's a reason I only recommend ones I'm confident will perform like the sub is intended to. 

[m_ms]

On 12/6/2021 at 11:26 PM, Ricci said:

I've not actually tested or listened to the Skram yet. I do have a pair of Skhorns which should sound very similar in character. I sold my Othorn's awhile back. I do prefer the Skhorn / Skram sound. To me it is slightly more clean, more flexible, easier to build, smaller and can avoid some of the resonances that show up in TH's. I spent a lot of time trying to clean these up in the Othorn design. TH's can sound very good and the Othorn was the best I've heard or seen measured. 

I'm sure a pair of Othorn's would be a delightful addition in my setup, but if the Skram's are their equal (with an edge in some respects) while being an easier build, slightly smaller etc., that's the way to go for sure. Many if not most things being equal I prefer cleanliness of reproduction with a more extended upper range via the Skram's, where it seems the prowess of the Othorn's is in the lower near tune performance. I take it the differences here are subtle, though. 

On 12/6/2021 at 11:26 PM, Ricci said:

Every sub I design has priority #1 of low distortion, high headroom, high damping. Those aren't always complimentary goals. They aren't always easy to accomplish with high order designs either. 

As far as drivers go the best ones are expensive. Most of what I design requires them due to the priorities and attributes chosen. Any old driver will make noise in any cab but there's a reason I only recommend ones I'm confident will perform like the sub is intended to. 

Impressive design goals and getting them to meet. Never cared for the Devastator variant(s) as it seems they're going rather blindly after extension, but at what cost in other areas of overall bass reproduction? They also take up more space. 

I assume top your list of the best drivers for the Skram design includes the Lavoce SAN214.50 and B&C 21DS115-4, or are you referring mostly to the Eminence, IPAL or 21SW152?

[peniku8]

23 hours ago, m_ms said:

Never cared for the Devastator variant(s) as it seems they're going rather blindly after extension, but at what cost in other areas of overall bass reproduction? They also take up more space.

I'd not say the devs are cabs that are blindly going after extension. I'd rather attribute that to simple vented designs like the Marty line for example. The devs are band pass designs, which increase sensitivity and should decrease distortion in the mid-upper bass region, depending on the slot length (there are like half a dozen dev designs that I am aware of). Additionally they bury the driver, which protects the membrane, which is something I like.

Never personally built/heard or dug into the measurements of these, so I can't comment on the design itself, but it theory it can be pretty good. Lately I've been very intrigued and impressed by designs with shaped/heavily flared ports, but these are extremely hard to build sadly, if you want to make everything out of wood (and sturdy).

[m_ms]

6 hours ago, peniku8 said:

I'd not say the devs are cabs that are blindly going after distortion. I'd rather attribute that to simple vented designs like the Marty line for example. The devs are band pass designs, which increase sensitivity and should decrease distortion in the mid-upper bass region, depending on the slot length (there are like half a dozen dev designs that I am aware of). Additionally they bury the driver, which protects the membrane, which is something I like.

Never personally built/heard or dug into the measurements of these, so I can't comment on the design itself, but it theory it can be pretty good. Lately I've been very intrigued and impressed by designs with shaped/heavily flared ports, but these are extremely hard to build sadly, if you want to make everything out of wood (and sturdy).

I did mean and actually wrote extension and not distortion  I too can only speculate on the Devastator's and their design and performance specifics, so pardon for assuming what I know not, but added extension (and size) seems to be general thing with these, and so I'm wondering how that impacts upper band extension and overall behavior here compared to the Skram's and their design parameter goals.

My intention implementing a pair of Skram's at a future point in my setup is to have a cleaner upper range (for a cleaner upper bass/lower mids - a vital area in sound reproduction - and also to be given more free reigns wrt. XO frequency to the mains), slightly more midbass energy/overall visceral impact and reduced size (from 20 cf. to 16 cf.), whilst also having the opportunity to tweak the tune. A pair of Dev's in some variation would likely defeat the purpose of mine, certainly with regard to size, so regardless of their qualities they're not an option in my case. 

[peniku8]

5 hours ago, m_ms said:

I did mean and actually wrote extension and not distortion

I did mean but not actually wrote extension lol, sorry for the confusion. Fixed now

For upper/mid bass a long horn will be better than a single bandpass, since it increases efficiency, and thus decreases relative distortion levels. A simple slot 'loaded' bandpass will do the same, but a bit less overall, emphasize upper bass less and maybe yield better results in mid bass if the resulting front 'chamber' volume is larger. Been some time since I designed my last cab in hornresp and played around with this stuff, but design approaches will be pretty good for music.

Group delay might become an issue if the front slot is very long, I'm not sure. But that's probably talking extreme lengths you'd typically not reach, which would also kill upper bass.

[h3idrun]

Lots more killer setups in here since my last visit!

Ive now build my 4th, which is the wonkiest so far and somehow the port sizes on the 2nd pair ended up different to the first pair but its not bad enough to notice too much of an audible difference at a party.

Also got access to a new warehouse to store them so I can finally play around with positioning and tuning and whatnot, this along with my new amps for the tops has taught me that I need at least 2 more haha.

Next party will be at the beach in a couple of weeks, before a big one for new years which im very excited about.

[m_ms]

(Off-topic, I know, but had to get below off my shoulders)

Please consider the following info from Magico's homepage on their Q subs:

Quote

Built around the renowned Q platform, the Q-Subs set new standards in low frequency sound reproduction. Capable of delivering 136 dB sound pressure level with less than 1% total harmonic distortion at 20Hz[i], the message is simple: if you think you have heard low frequencies before, think again.

https://www.magicoaudio.com/q-sub

136dB's at 20Hz with less than 1% distortion? They sport two sub models, one featuring 2 x 15" woofers and the other 2 x 18" woofers. Sensitivity is a rated 90dB's for both models with 2000W and 4000W amps respectively. The sealed(?) enclosures are made of aluminum and are extremely inert and heavy. 

Did I miss anything here, or did Magico reinvent the wheel with these specs? Going by sensitivity and amp power rating I can only muster up a max SPL of some (including loosely estimated power compression at full click) ~120dB and upwards of ~125dB's respectively, not bad by any means, but still way off the claimed 136dB's. And 1% distortion at 20Hz at 136dB's - if I'm reading the above correct?!