Ricci's Skram Subwoofer & Files

[kipman725]

On 9/20/2022 at 8:55 AM, Mike said:

Hi All, Finally I have all the parts for my for my active versions built. I'm using NSW6021-6 21"  with Loto Dsp amp module from powersoft with either the 3004PFC2 or 4HV amplifier amp modules, I might try both amps options...The DSP has a few limit options available. What's the best value for the NSW6021-6 driver for the following limiters.  

1, TruePower TM

2, RMS Voltage

3, RMS current

4, Peak Limiter

 

Thanks

this document from powersoft has some guidelines (6" coil): https://www.powersoft.com/wp-content/uploads/2019/01/powersoft_TN009_LimiterSetup_en_v1.0.pdf

Limiters are also a function of the box design and to an extent the program material.  They are used to prevent over excursion and thermal damage.  You can check this in Hornresp but I don't think the amplifiers above have enough output voltage with this driver to cause over excursion with an appropriate high pass filter.  Then you are just left with thermal damage for which you want the TruePower limiter.  To set this you start at a low value and measure magnet temperature* over a long period of time while running program material that is heavily compressed by the limiter.  Adjust up the limiter slowly (it may take on the order of an hour for the magnet temp to stabilize) until you reach the maximum magnet temp you want to allow (<100C !).  This procedure takes a long time, makes a lot of noise and may destroy your driver...   

 

[m_ms]

On 9/14/2022 at 11:22 PM, jay michael said:

My pair of Danley sh46 are a pretty good match for 6 skrams, but they still outrun them a bit. I think 8 skrams would be the perfect balance. I've got another pair of skrams in the cutting phase, and another pair of sh46 on the way. Lots of skrams popping up in my area, there will be 12 in my city pretty soon, as well as 8 or 10 on the island. Been some planning discussing how to get them all in the same place sometimes soon

I'm planning an after summer report soon, was hectic busy with lots of great gigs

 

On 9/16/2022 at 4:44 AM, jay michael said:

I'm using the 21sw152. Sh46's can get stupid loud, especially when bi-amped. Two pair of them can cover 1500 to 2000 people for electronic dance music. While the Skram can really boogie,  its still a medium sized cabinet compared to other types of designs. Pretty typically for the Danley guys to recommend 6 th118's per pair of sh46, so I'd say my assessment is pretty accurate. This would be for heavy bass music mind you, for techno you could probably get away with fewer

When you say a pair of DSL SH46 "outrun" 6 Skrams, is that simply in reference to the total output the SH46's are capable of by comparison, or is it more of a "feel" for the energy-balance between the SH46's and Skrams in the sort of venue you're using them? I presume the Skrams are dialed in somewhat hotter vs. the DSL's and therefore also run out of steam earlier/need more headroom to keep up?

As a thought experiment, say you were using a pair of SH46's in a home environment in a moderately sized listening room (I know, overkill, but bear with me). Would 2 Skrams suffice augmenting them here, i.e.: provide a proper mains/subs balance, or would more of them be necessitated in such a listening milieu in conjunction with the DSL's? 

Lastly, is a single DSL TH118 comparable to a single Skram in output, even though the TH118 only uses an 18" vs. a 21" in the Skram? And in case, does the TH118 therefore make more effective use of a given driver diameter in given enclosure volume due a more outright horn-loading of the back wave of its driver, while also making use of the front wave? Both of them are high order bandpass designs, but the Skram is using a somewhat shorter "horn" loading..  

[jay michael]

1 hour ago, m_ms said:

 

When you say a pair of DSL SH46 "outrun" 6 Skrams, is that simply in reference to the total output the SH46's are capable of by comparison, or is it more of a "feel" for the energy-balance between the SH46's and Skrams in the sort of venue you're using them? I presume the Skrams are dialed in somewhat hotter vs. the DSL's and therefore also run out of steam earlier/need more headroom to keep up?

As a thought experiment, say you were using a pair of SH46's in a home environment in a moderately sized listening room (I know, overkill, but bear with me). Would 2 Skrams suffice augmenting them here, i.e.: provide a proper mains/subs balance, or would more of them be necessitated in such a listening milieu in conjunction with the DSL's? 

Lastly, is a single DSL TH118 comparable to a single Skram in output, even though the TH118 only uses an 18" vs. a 21" in the Skram? And in case, does the TH118 therefore make more effective use of a given driver diameter in given enclosure volume due a more outright horn-loading of the back wave of its driver, while also making use of the front wave? Both of them are high order bandpass designs, but the Skram is using a somewhat shorter "horn" loading..  

I think the combination of SH46 and Skram is just simply a great pairing sound and power wise. The horn loaded upper bandwidth of the Skram really compliments the sound character of the SH46, together they sound very clean with well defined impact, some would describe it as having "fast bass".  For an example, If there is a genre of music that I've heard sound shit on a lot of sound systems, its psytrance. Something about those fast upper bass notes just seem to show the warts on many sound systems. The Sh46 Skram combo sounds better on psytrance than anything else I've ever heard, F1, Void, Turbo etc etc. On top of that, one of my biggest rental clients is a long standing local crew that specializes in bass music, dubstep, drum and bass etc.  They like the Skrams so much they are now building their own. For reference, this same crew was previously a heavy renter of PK sound, which some people say is the yard stick for bass music subwoofer's.  So yeah, the Skram is an exceptionally flexible cabinet, it really can do all the things well.

To your original question, I would add that when my 6 Skram's start touching limiting, the Sh46's still have a few db of headroom to go. Personally I'd say the appropriate sub to sh46 ratio would be 6 to 7 skrams per pair of sh46. I've got another pair of SH46 on the way, with a couple more Skrams in the cnc cue, if I have another successful summer next year maybe Ill cut up another 4.

Th118 vs Skram, I think Josh would be a better person to answer that one... they must be fairly close in output overall, but I'm just speculating

[peniku8]

Based on the TH118's spec sheet I'd guess it's giving up some low end (its F4 is at 37Hz) for a bit of added sensitivity at higher frequencies, which might mean that in its passband, the TH118 would be able to keep up with the Skram, but below 40Hz the Skram will outrun it pretty quickly. I didn't look at cab volumes and the best data point would be CEA2010 ratings for both made by the same person, so take this with a grain of salt.

Any horn-kind of design doesn't lend itself well to going deep while being space-efficient, I feel. The Skram is a hybrid, which kinda gives it the best of both worlds.

[Ricci]

I'd agree with Peniku8 on that comparison based on the available info. 

[Aaron Smith]

On 9/28/2022 at 4:55 PM, jay michael said:

I think the combination of SH46 and Skram is just simply a great pairing sound and power wise. The horn loaded upper bandwidth of the Skram really compliments the sound character of the SH46, together they sound very clean with well defined impact, some would describe it as having "fast bass".  For an example, If there is a genre of music that I've heard sound shit on a lot of sound systems, its psytrance. Something about those fast upper bass notes just seem to show the warts on many sound systems. The Sh46 Skram combo sounds better on psytrance than anything else I've ever heard, F1, Void, Turbo etc etc. On top of that, one of my biggest rental clients is a long standing local crew that specializes in bass music, dubstep, drum and bass etc.  They like the Skrams so much they are now building their own. For reference, this same crew was previously a heavy renter of PK sound, which some people say is the yard stick for bass music subwoofer's.  So yeah, the Skram is an exceptionally flexible cabinet, it really can do all the things well.

To your original question, I would add that when my 6 Skram's start touching limiting, the Sh46's still have a few db of headroom to go. Personally I'd say the appropriate sub to sh46 ratio would be 6 to 7 skrams per pair of sh46. I've got another pair of SH46 on the way, with a couple more Skrams in the cnc cue, if I have another successful summer next year maybe Ill cut up another 4.

Th118 vs Skram, I think Josh would be a better person to answer that one... they must be fairly close in output overall, but I'm just speculating

Hey Jay, 

I was wondering if your CNC guy would be interested in cutting another 8 of these cabs? I have Tannoy VQ60 boxes (2 active, 3 passive...138 dB, 144 dB) and am looking for some stands for them, lol! I'm not in the SR biz, but was considering renting some of this gear out locally as I won't be building the big shop that will be getting some of this stuff for awhile.

 I'm a little south of you in Montana...my mom (RIP 4.20.20) was born in Edmonton and most of my family still lives in AB and BC to this day. I get up to within 50 miles of AB every couple months and could detour north for the right reasons. 😁 

[radulescu_paul_mircea]

I have a version of SKHorn that is larger than the original, it's extremely close to a pair of Skrams in dimensions and it's loaded with a pair of 21" Ipal drivers. I tested it with CEA bursts and recorded the max level of a few more subs, including TH118. Usually, the tests were done with a bridged K20, an ISEmcon mic or earthworks M30, at 4 m and every time the system was calibrated with a B&K calibrator. 
2*TH118-8ohm versions on a FP14000 bridged 25, 28, 31.5, 40, 50, 63, 80 Hz values

116, 130.3 , 132.0 , 135.0, 136.3, 139.4, 140.2 dB  at 2 m 

You can compare to SKhorn measurements from data-bass and you'll see it's just about the same level difference as the difference in drivers and enclosure dimensions, meaning about 3 dB overall. You loose that when you go for a more normal 21", but I gained about 2 dB from the larger enclosure in the deep end and larger ports, which I believe will be the case with SKrams. 
That's the thing, they made the TH118XL that can get you about 6 dB more at 30 hz compared to the smaller version, at the expense of the max level at 45 hz where you get into excursion limit. I believe a Skram loaded with 21DS115 or similar will be a bit lower in output at 30 hz and on par everywhere else wtih TH118XL.

another very important aspect is the fact that the sound is so much different! Tapped horns have an extremely clean sound at LF tuning, they have so much more surface than a port so they tend to be cleaner down there , but they don't feel as tight and as punchy as BPHs .

in my experience, for very deep bass music, I tend to like TH a lot more, they can keep up better with heat and they sound so smooth! Very large horns are even better, like BC218 but those are just for installs IMO.

For all-round use, I'd go either with my dual 21BPH or with simple well designed reflex subs. because right now, reflex with L-Ports like L-Acoustics , but loaded with NTLW-5000 series from eighteensound, tuned to 27 hz, is something one should hear to believe! 

[kipman725]

In the UK the psytrance scene is into using Opus  systems which have custom linear amplifiers (that are possibly the most dense objects in the universe), 25mm thick cabs and sometimes exotic drivers like TAD.  Only reflex loading ASFIK.

 

[Rune JS]

On 2/15/2020 at 1:05 AM, N8DOGG said:

Well, I finally got mine built! Lol took a while but life got in the way. I'm also just staring to do my fiber optic ceiling, so multiple things at once!.

I should have the subs up and running next week. Drivers are DS115.

Just getting duratex. Will be my nearfield subs lol.

Nice work!

I do not see any screw holes or dados from a CNC router. Have you only used glue?

[m_ms]

Thanks for your replies, @jay michael and @peniku8. It certainly appears the Skram is a very versatile performer, and that from a fairly limited size all considered and still hitting quite deep in frequency. An impressive combo. And of course, yes - the TH118 trades a few extra dB's in sensitivity with less extension compared to the Skram. I should've looked at little closer at the specs.. 

On 10/2/2022 at 9:20 PM, radulescu_paul_mircea said:

another very important aspect is the fact that the sound is so much different! Tapped horns have an extremely clean sound at LF tuning, they have so much more surface than a port so they tend to be cleaner down there , but they don't feel as tight and as punchy as BPHs .

in my experience, for very deep bass music, I tend to like TH a lot more, they can keep up better with heat and they sound so smooth! Very large horns are even better, like BC218 but those are just for installs IMO.

Interesting findings on the sonic differences here. They would seem to mirror what I've read earlier in this thread in a comparison between the Othorn and Skram. I use a pair of tapped horns myself (15"-loaded with a ~23Hz tune, @20cf. volume per cab), and can relate to your descriptions. They're just effortless or unflappable and indeed very smooth sounding down low, and I find that to be a great trait also when watching movies on Blu-rays/4K UHD's. The sheer LF output from movies on named formats can be quite overwhelming, not least when reproduced so cleanly and forcefully, and I remember settling on the TH principle (instead of the more classic FLH) to more readily accommodate movie soundstracks (in conjunction with music playback) and their potentially prodigious LF output, with TH's having excursion minima at the tune.  

[Rune JS]

On 9/14/2022 at 8:06 PM, Tahoejmfc said:

Welcome to the Rabbit hole of BASS! Correct me if I am wrong with any of this.......

I use the B&C 21SW152's at 4ohm with a QSC PL380 amp. This amp drives 2 SKRAMS, with room to melt the coil if you turn the clip limit switch off.(I know from accidental experience) I have thought about running 4 x 8 ohm drivers with this one amp in series as well, but figure that would be pushing the amp alot and I typically use the amp at Burning Man and it was %*&#^@ hot this year so it prolly would not be the best idea as the amp would be turned all the way up instead of running at 50-60% like I currently am. I pair the 2 SKRAMS with Meyer Sound UPJ's and run the tops at -6db for most outdoor venues and -10db for most indoor venues (unless it gets really crowded, then I go to -4db outdoors for the tops and -6db for indoor.... Otherwise the tops are Too Bright). I have Meyer Sound UPQ's on order and will need to double my SKRAMS to keep up with the UPQ's output so I plan on building 2 more of these unless I just go straight to the Powersoft 30" M-Force subs but they are 12,000$ a pair with amp and you have to wait a year to get the drivers.

If you are going with 6 SKRAMS you will need quite the tops to compete as these Bass Bins output some serious BASS!!! Jay on here has quite the system with I think it was Danley tops, he might be one to DM. 

I would always cut in the grooves to build these boxes, serious forces going on here and you need the cabs to be rock solid, make sure you use the best Baltic Birch you can find, PU Glue and lots of pre-drilled screws. One option if you do not have access to a CNC router is to find a local makers space that has one, I used the TRUCKEE ROUNDHOUSE shop bot to make mine. 

GOOD LUCK AND MAY THE BASS BE WITH YOU!

What were the dimensions of the screws you used for the assembling? 

[benpt]

Where can I access the Skram files? I can see them on the thread but it says they are unavailable, do I need anything specific to access them?

[benpt]

Heres the cutlist for 2440x1220 ply

Skram 12mm cutlist.pdf Skram 2440x1220x18mm cutlist (1).pdf

[N8DOGG]

On 10/7/2022 at 9:30 AM, Rune JS said:

Nice work!

I do not see any screw holes or dados from a CNC router. Have you only used glue?

Yes, glued and clamped with some Brad nails in some parts 

[Leimahmood]

is there any cnc cut list for mdf sheet 4feet x8 feet

[klipsch]

There are dxf files in the beginning of the thread - the CAM work can be done using those CAD files

[h3idrun]

On 11/21/2022 at 12:32 PM, Leimahmood said:

is there any cnc cut list for mdf sheet 4feet x8 feet

It literally 2 comments above yours lol

[Sushi]

Hi everyone! Thanks for this interesting thread, and thanks Josh Ricci for this brilliant design! I've red the thread multiple times last year and i'm reading most recent posts today. Now i'm actually looking forward to build my first pair of Skrams! 🥳

First of all, i would like to make a slight change in the port layout, using 2x18mm braces (instead of 3x12mm) to match the double braced horn mouth. On paper this should make no change in port tuning, as it would not alter the total port area.. it would obviously limit low tuning options (having one vent duct less to block) but it won't be a problem for me honestly.. i'd rather be more worried about having less bracing on the port, but in my experience 2x 18mm panels  should be enough to brace a 600mm surface.. never built a cab for a strong motor 21' driver though, so please feel free to give your opinion about any nasty consequences this mod could cause!

i'd like to use B&C 21DS115 8ohm, but i've also considered the SAN214.50 cause it is way cheaper and i've seen many are using it with good results.. no chance they would match B&C quality, but it seems they are worth their price.. 8ohm impedence would be my choiche anyway, as i plan to build two more subs in the future and run them parallel, 2 drivers on each channel of a 2ch amplifier. Amp will probably be a CVR D3302 which i've seen used succesfully by Jay (props for you mate, and congrats for your system development, you did a great job).

I already have some baltic birch ply and i'm lucky enough to have a friend who works as a full time carpenter and CNC operator. We both have some experience in speakerbuilding. We just have to find the time to draw the box on cad and make some long awaited sawdust.

If there's any advice you guys feel you can give me, i'm all ears! Cheers!

[klipsch]

On 11/27/2022 at 8:53 AM, Sushi said:

Hi everyone! Thanks for this interesting thread, and thanks Josh Ricci for this brilliant design! I've red the thread multiple times last year and i'm reading most recent posts today. Now i'm actually looking forward to build my first pair of Skrams! 🥳

First of all, i would like to make a slight change in the port layout, using 2x18mm braces (instead of 3x12mm) to match the double braced horn mouth. On paper this should make no change in port tuning, as it would not alter the total port area.. it would obviously limit low tuning options (having one vent duct less to block) but it won't be a problem for me honestly.. i'd rather be more worried about having less bracing on the port, but in my experience 2x 18mm panels  should be enough to brace a 600mm surface.. never built a cab for a strong motor 21' driver though, so please feel free to give your opinion about any nasty consequences this mod could cause!

i'd like to use B&C 21DS115 8ohm, but i've also considered the SAN214.50 cause it is way cheaper and i've seen many are using it with good results.. no chance they would match B&C quality, but it seems they are worth their price.. 8ohm impedence would be my choiche anyway, as i plan to build two more subs in the future and run them parallel, 2 drivers on each channel of a 2ch amplifier. Amp will probably be a CVR D3302 which i've seen used succesfully by Jay (props for you mate, and congrats for your system development, you did a great job).

I already have some baltic birch ply and i'm lucky enough to have a friend who works as a full time carpenter and CNC operator. We both have some experience in speakerbuilding. We just have to find the time to draw the box on cad and make some long awaited sawdust.

If there's any advice you guys feel you can give me, i'm all ears! Cheers!

I wish I had added some double sided work on the bottom panels for assembly to make clamping easier for those areas (the panels around the tuning ports). Everything else was fine for assembly. 

Good luck!

I'm a buy once, cry once type of individual - I'd go B&C or Eminence, unless you aren't the type of person that will wonder 'what if' by going with a "lesser" driver. 

[Sushi]

2 hours ago, klipsch said:

I wish I had added some double sided work on the bottom panels for assembly to make clamping easier for those areas (the panels around the tuning ports). Everything else was fine for assembly. 

Good luck!

I'm a buy once, cry once type of individual - I'd go B&C or Eminence, unless you aren't the type of person that will wonder 'what if' by going with a "lesser" driver. 

I think i'm going to put dowels or maybe milled grooves to keep panels in place during the building process, i usually do that along with clamping and shooting nails. This will help a lot, also for the rest of bracing panels for the chamber (which i will probably make out of 15mm birchply, mostly cutouts i've got laying around from other builds)

I'm quite the same kind of person too, once i commit in a project i aim at best results, despite my modest means. I would probably choose B&C because it's one of the best and it's easily available in my country. I am curious though, about those italian designed/chinese manufactured speakers as more and more builders are finding them to be a valid choiche. 

[jay michael]

I second going for the better driver, more of an investment upfront but it will never leave you wondering what you are missing. Good luck with the build! I'm currently piecing together another pair.

[Mike]

Thanks for the link to Limiter guideline. My active version of the Skram's is done. I just need to load the Eminence's and setup the limiters.

On 9/27/2022 at 1:13 AM, kipman725 said:

this document from powersoft has some guidelines (6" coil): https://www.powersoft.com/wp-content/uploads/2019/01/powersoft_TN009_LimiterSetup_en_v1.0.pdf

Limiters are also a function of the box design and to an extent the program material.  They are used to prevent over excursion and thermal damage.  You can check this in Hornresp but I don't think the amplifiers above have enough output voltage with this driver to cause over excursion with an appropriate high pass filter.  Then you are just left with thermal damage for which you want the TruePower limiter.  To set this you start at a low value and measure magnet temperature* over a long period of time while running program material that is heavily compressed by the limiter.  Adjust up the limiter slowly (it may take on the order of an hour for the magnet temp to stabilize) until you reach the maximum magnet temp you want to allow (<100C !).  This procedure takes a long time, makes a lot of noise and may destroy your driver...   

 

 

 

 

 

 

 

 

[Sushi]

👏👏👏 nice looking build! That amp module on the back definitely give it a pa style pro look! I would have just recessed it a bit from the back panel's surface, to avoid hits or scratches during load out or such things.. whatever, it's a really good job anyway!  What kind of paint did you use for the finish? 

Jay: so you will soon have 8 of these badboys, or are you planning to build more? How do you plan to you drive them?  ...also, for my setup, would you say one CVR D3302 with 4 Skrams (2 on each channel in 4ohm load) is a good working combo? 

 

[Ricci]

Good job Mike. Those look excellent. 

[chrapladm]

Ricci would the Beyma 21LEX1600Nd  work in the Skram or Skhorn?

 

I simulated the driver and it looks doable but SW152 looks much better. Problem is the BC is $2500aud each almost. The Beyma is much cheaper. The eminence is also around 3000 each.

 

I was going to get another pair of 21SW152's but the price isnt making it impossible. AND NSW6021 is cheaper now than the SW152 but did Eminence improve their QC issues?