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Ricci's Skram Subwoofer & Files


Ricci

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The Sanway "clones" may perform better or worse than the similarly named Lab Gruppen brand amps.  I'm not even sure how closely the Sanway amps resemble the original designs.  The "clone" may just be in the branding.  It actually wouldn't shock me if the Sanway amps actually perform better.  Of course, I doubt anyone will be buying and measuring one of the original ones any time soon.

That said, while 130 ms might be OK for rock kick-drum, dub-step and related genres typically have bass with a lot more compression.  In my example track from above, the "average power is 1/4th of max" applies when I analyze the whole song, which has a few brief breaks from the sustained bass.  If I exclude those brief rest intervals, the average is closer to 1/3rd the max for passages that are a minute or longer!

This suggests that one should provision *a lot of spare headroom* into systems that play this kind of music and pay much more mind to long-term power capabilities in components.  For example, the 21SW152s may have an edge over the DS115s for such systems, and it's definitely important to know how much output an amp can sustain for those minute long sustained bass passages.  :)  I wish there was an easy / straight-forward answer, but a lot really depends on details including the particulars of the content.  One of the nice things about over-provisioning an audio system if one can afford to do so is worrying less about accidentally taking it too far and breaking something.

Regarding wiring, I assumed the 4mm figure indicated by @domme referred to diameter and not cross-sectional area, which would have units of mm^2.  A cylindrical wire with 4 mm^2 of cross-sectional area is about 2.25 mm diameter.

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6 hours ago, SME said:

The Sanway "clones" may perform better or worse than the similarly named Lab Gruppen brand amps.  I'm not even sure how closely the Sanway amps resemble the original designs.  The "clone" may just be in the branding.  It actually wouldn't shock me if the Sanway amps actually perform better.  Of course, I doubt anyone will be buying and measuring one of the original ones any time soon.

That said, while 130 ms might be OK for rock kick-drum, dub-step and related genres typically have bass with a lot more compression.  In my example track from above, the "average power is 1/4th of max" applies when I analyze the whole song, which has a few brief breaks from the sustained bass.  If I exclude those brief rest intervals, the average is closer to 1/3rd the max for passages that are a minute or longer!

This suggests that one should provision *a lot of spare headroom* into systems that play this kind of music and pay much more mind to long-term power capabilities in components.  For example, the 21SW152s may have an edge over the DS115s for such systems, and it's definitely important to know how much output an amp can sustain for those minute long sustained bass passages.  :) I wish there was an easy / straight-forward answer, but a lot really depends on details including the particulars of the content.  One of the nice things about over-provisioning an audio system if one can afford to do so is worrying less about accidentally taking it too far and breaking something.

Regarding wiring, I assumed the 4mm figure indicated by @domme referred to diameter and not cross-sectional area, which would have units of mm^2.  A cylindrical wire with 4 mm^2 of cross-sectional area is about 2.25 mm diameter.

Yea, it all depends on the gig. If you need those long sustained bass notes you'll have to think about getting more drivers, but you can also save on amping by bringing one Speakerpower amp instead of two Powersofts or something. You'll lose 6dB of peak headroom or whatever, but you get the same sustained power with less gear. You might get away with 1KW of amping per driver for such gigs, depending on how hard the source content is compressed.

About the wiring, it seems the "²" might not be displayed on your device properly, Domme and I both used "mm²" units, which is the same as mm^2 or sqmm.
Here is a pic what it should look like: grafik.png.f85cd485cee3b8ef63b120450721273d.png

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On the wire ratings, sorry my mistake!  I reviewed the posts, and my display is working fine.

For my home subs, I used 4-conductor 10 gauge cable (5.25 sq mm), one cable to each cabinet for a total cross-section of 21 sq mm for the 12 kW amp, and the loads are closer to 4 ohm.

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https://www.china-sanway.com/D20KQ-4-Channel-Class-D-Digital-DSP-Amplifier-16000W-for-Subwoofer-pd49629476.html

I suspect the latest Sanway amps are at least a development on the original LG designs as the power levels are beyond the amplifiers that they are meant to be a clone of: https://www.prosoundnetwork.com/gear-and-technology/labgruppen-fp-series-amplifiers

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Thanks everybody for the input and interesting amp discussion. I'm gonna be using an original FP10kQ and I am considering to get another one. I think one on each side would be a good start with huge headroom for a 3-way system and I would still have enough capacity to double up at a later point or migrate to 4-way with another amp.

Anyway, cabinet building is coming closer and I am just studying the plans and converting the measurements to round metric numbers. Does anybody know why there is this 45° cut in the front panel C? I think it will get used as a handle in combination with the back-side hatch handles and now I am afraid that the sharp corner might break at some point and/or lead to injuries. I would prefer to use a rounded edge instead if it doesn't serve a meaningful purpose.

Cheers,
Domme

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On 12/20/2021 at 8:44 PM, Ricci said:

Did you try listening to music that has deep bass <40Hz? You should hear a huge difference. 

Everyone has their preferences for sound but personally I'm not a fan of running a 4 or 5 way rig with the bandwidth split up into tiny segments in the bass range. When I see the picture of the stack with the Skrams you posted...I think that 1 or 2 more Skrams sitting in place of the MBM's and running the whole bandwidth would be better. That's just me though. 

Hi, I agree with you @Ricci that two extra skram would do the job without bph kicks. I connected it to a D&B amplifier and put it to work as 21S SUB the same of them (since there is no setup but the model is chosen) and oh how it works well the whole range up to 105Hz - (-5db) with their settings,
Unfortunately the problem is that we currently have them two and no money for other two and in this situation I sacrifice the SPL to go low, an additional two skram could then do both but as SME and Peniku stated many times the basses are cut and the music is listened to without skram and at one point the magic just appears : D

 

On 12/20/2021 at 8:44 PM, Ricci said:

Interesting comparison...I'm not surprised that the scoops sound totally different. Scoops are really efficient over a narrow bandwidth. The trade off for the efficiency is peaky response, limited bandwidth, limited low frequency output and BIG size. Most of them are huge cabs but really only have LF extension to 40-45Hz. What 's the dimensions for those scoops? Those look BIG. I've never seen any in depth measurements of a good scoop design. 

This is the box made for PD2150-(636,1320,798), it is quite big and not modified for b & c 21 ds115 .. If you are interested I have a slightly different scoop design that I modified for 21ds115 and I am currently waiting for a colleague to make it but as it started I will before: D this is from hornresp .. of course his purpose is to go low and have a spl -  mine is 636x1466x836(w-h-d)
 

scoop.JPG

21LUKICA.png

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21 hours ago, Domme said:

Thanks everybody for the input and interesting amp discussion. I'm gonna be using an original FP10kQ and I am considering to get another one. I think one on each side would be a good start with huge headroom for a 3-way system and I would still have enough capacity to double up at a later point or migrate to 4-way with another amp.

Anyway, cabinet building is coming closer and I am just studying the plans and converting the measurements to round metric numbers. Does anybody know why there is this 45° cut in the front panel C? I think it will get used as a handle in combination with the back-side hatch handles and now I am afraid that the sharp corner might break at some point and/or lead to injuries. I would prefer to use a rounded edge instead if it doesn't serve a meaningful purpose.

Cheers,
Domme

I am also interested to know if 45° cut is necessary for panel C? Is there a risk of aerodynamic noise with 90° cut? I am currently working on OpenSCAD model with goal of exporting CNC data and for now I left the panel with 90° cut as I am not sure how 45° cut could be manufactured by CNC.

SKRAM_OpenSCAD_20220113.png

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4 hours ago, DaMar42 said:

I am also interested to know if 45° cut is necessary for panel C? Is there a risk of aerodynamic noise with 90° cut? I am currently working on OpenSCAD model with goal of exporting CNC data and for now I left the panel with 90° cut as I am not sure how 45° cut could be manufactured by CNC.

 

This will be fine. These are very minor details. Do not worry. 

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18 hours ago, ChikoRomantiko said:

Hi, I agree with you @Ricci that two extra skram would do the job without bph kicks. I connected it to a D&B amplifier and put it to work as 21S SUB the same of them (since there is no setup but the model is chosen) and oh how it works well the whole range up to 105Hz - (-5db) with their settings,
Unfortunately the problem is that we currently have them two and no money for other two and in this situation I sacrifice the SPL to go low, an additional two skram could then do both but as SME and Peniku stated many times the basses are cut and the music is listened to without skram and at one point the magic just appears : D

 

This is the box made for PD2150-(636,1320,798), it is quite big and not modified for b & c 21 ds115 .. If you are interested I have a slightly different scoop design that I modified for 21ds115 and I am currently waiting for a colleague to make it but as it started I will before: D this is from hornresp .. of course his purpose is to go low and have a spl -  mine is 636x1466x836(w-h-d)
 

scoop.JPG

21LUKICA.png

Chiko,

I understand. Not everyone has enough budget to build many smaller cabs.

This is a big cab...About the size of a Skhorn. 30Hz is pretty low for a scoop and requires a lot of size. Im not sure I would like that big 70Hz peak followed by a hole in the response at 100Hz, which is part of the reason I'm not a scoop guy. I always planned to test a popular scoop design but never have. 

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  • 2 weeks later...

Hey everyone,

Ive been delving into the various sound system related groups on Facebook again and a name that keeps coming up is SB Audience, their subs are pretty popular in the Paraflex circles and they look to be a lot easier and cheaper to get a hold of than any of the recommended drivers for the SKRAM here in Australia.

Has anyone tried these in an SKRAM, specifically the Nero 21?

https://www.wagneronline.com.au/sb-audience-nero-21-subwoofer-1100w/sb-audience-range/sb-acoustics/speaker-drivers/audio-speakers-pa/nero-21sw1100d-89890/1002180/pd/

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SW and DS will be better than the SBA in every regard. You'll probably lose like 2dB going with the SBA. If you don't mind saving a buck I guess they're fine, but as soon as it means bringing 4 vs bringing 6 cabs or 6 vs 8 I'd say go with B&C, even if they're twice the price imo. How much is the Eminence in Australia?

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The problem is shipping, last time I looked at B&C drivers it was over $700 to get them from America, and not much less from Europe, I could get a whole extra driver for the price of shipping the SBA

EDIT: Just double checked and getting 4x Neros from wagner is just over $3k Australian shipped, getting 4x SW152s from parts express is nearly $4k but im not sure if thats Aus dollars or USD, if the latter then its nearly $5500 which means i could almost buy 8 Neros for the same price

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AUS pricing for audio gear has always seemed crazy to me. Is there no authorized dealer for B&C / Lavoce / 18 Sound etc in AUS that maintains stock?

EDIT: A quick search didn't bring up much. The B&C website lists one distributer in NZ but their website doesn't inspire much confidence. Mostly looks like a rental outfit for events. 

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The maximum peak SPL spec is essentially meaningless but I can tell you from comparing the SKRAM to FANE 18XB reflex subwoofers in simulation 4 SKRAM with B&C 21DS115-4 will surpass the output 10 40Hz tuned 18XB loaded reflex boxes.  So to surpass the output of your 4 single 18" subs I would expect you to need two SKRAM.

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On 1/27/2022 at 10:16 PM, kipman725 said:

The maximum peak SPL spec is essentially meaningless but I can tell you from comparing the SKRAM to FANE 18XB reflex subwoofers in simulation 4 SKRAM with B&C 15DS115-4 will surpass the output 10 40Hz tuned 18XB loaded reflex boxes.  So to surpass the output of your 4 single 18" subs I would expect you to need two SKRAM.

Thanks for the reply....Sorry I should have been more specific. The subs I'm currently using are 4 Axiom Proel 18" subs.Loaded with 18Sound Neo drivers and 2000w Powersoft  plate amps..Not a DIY. I'm looking to down size in terms of number of subs. Will 2 skram outperform the 4 single 18's. I do mainly live band stuff. Output Below 30Hz not required.  Thanks

 

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My carpenter friend is unhappy with using 12mm plywood for the vent section (parts "I") because he wants to use lamellos for easier assembly and thinks 12mm might be too thin for them. I assume that if we use 18mm plywood instead and just make the whole cabinet 18mm wider to preserve the vents' area it shouldn't be much of an issue in terms of tuning. Is this correct or am I missing something?

Best wishes for the weekend,
Domme

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On 1/28/2022 at 10:25 AM, Domme said:

My carpenter friend is unhappy with using 12mm plywood for the vent section (parts "I") because he wants to use lamellos for easier assembly and thinks 12mm might be too thin for them. I assume that if we use 18mm plywood instead and just make the whole cabinet 18mm wider to preserve the vents' area it shouldn't be much of an issue in terms of tuning. Is this correct or am I missing something?

Best wishes for the weekend,
Domme

I assume he is not making Dado joints with a CNC, if he wants to use lamellos. I'd personally just use 18mm ply for the braces and leave everything else as is. The impact will be so small, it's nothing to be concerned about. If you make the entire cab wider, the tuning will drop too, in theory. Both options may lower the tuning by as little as 0.25Hz or so.

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42 minutes ago, peniku8 said:

I assume he is not making Dado joints with a CNC, if he wants to use lamellos. I'd personally just use 18mm ply for the braces and leave everything else as is. The impact will be so small, it's nothing to be concerned about. If you make the entire cab wider, the tuning will drop too, in theory. Both options may lower the tuning by as little as 0.25Hz or so.

Thanks! He doesn't own a CNC router so we have to use lamellos instead or even do some manual routing of dado joints if unavoidable.

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I'm just getting back to audiofiling after a couple of decades. Not sure how much has changed but I have a quick question and I'm not sure where to ask so I'm trying this location. Years back I stumbled across a electronic circuit schematic that build a sort of in active EQ that would Flatline the response on a subwoofer in a small sealed enclosure. I remember reading that the small sealed enclosure exhibited a specific response and that this electronic circuit that you can build as an active EQ would Flatline that response. But I can't seem to find it anywhere on the internet today. Is there anyone that could help me figure this out or does anyone know of what this is called? Thank you

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George a Linkwitz transform circuit is likely what you are talking about. Other options are servo / active feedback sensing circuits or regular EQ can also be employed. 

Note that the output limitations, efficiency and power handling of the system are not changed by any of these methods. 

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