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Ricci's Skram Subwoofer & Files


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This is the long delayed single driver sub similar in design to the Skhorn. Overall the performance goals and criteria were quite similar. Big surprise there! The Skhorn works so well at what it does

So close.  Loading drivers and doing the wiring today 

Ok... report after 3 full days of Skram use.  Josh, thank you for this amazing design! I am simply blown away that this kind of performance can be had through diy designs, you are doing the music worl

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8 hours ago, h3idrun said:

Hey guys,

I built 2 of these monsters on Boxing Day last year (seemed appropriate) for a New Years party out in the Australian bush, its almost that time of year again and I plan do do 2 more this season so I thought it would be fitting to come back here and thank you for the excellent plans and a year of happy bassing!

I didn't (and still don't) have the money for some nice big PA 18"s nor the amps to run them so I am using 4x cheap 10" car audio drivers per box that i had laying around (Memphis SR10 to be precise) and I am blown away by the smooth low end output compared to any other party speakers ive used and even most big car audio systems ive heard (that was my background before moving into DJing and outdoor sound systems).

Wow.  Nice looking setup!

Just so you know, the frequency response / sound quality of these designs depends quite a lot on the drivers that are installed.  Using drivers with weak motor strength like the cheap car audio drivers you used probably won't sound nearly as good or give you nearly as much output as using driver(s) with a strong motor like the ones recommended.

If building new SKRAMs, I suggest going through the trouble of finding/buying nicer drivers for them, and if there's any possibility of modifying the old cabinets to accept better drivers, definitely consider doing that as well.

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3 hours ago, SME said:

Wow.  Nice looking setup!

Just so you know, the frequency response / sound quality of these designs depends quite a lot on the drivers that are installed. 

Thanks! 

I'm aware these won't even be close to the sound that the proper drivers and power will give, I have built them in such a way that the entire back panel is removable so I can cut a new baffle and add more bracing for the proper drivers when funds allow.

For now I'm blown away at the efficiency and smooth response already and I'm finding low end in songs I didn't know existed on local  club systems I've played on so I can't imagine what they will sound like with the proper drivers and a bucket load more power. 

I think the most power I've put into them so far is about 150w each so there's plenty of room for improvement in the future. I threw one into the back of my car for an audio meet once and pulled 125.7db at 33hz from the rear channels of my head unit (2x 8ohm drivers per channel) 😂

 

Need to do some proper testing with my UMIK and REW one day soon. 

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4 hours ago, chrapladm said:

How does this even simulate?

 

And a single 21" will smash four pro audio 10's VD wise. So I would maximise space first before building 4-8 with lesser drivers. BUT either way great to see others trying other drivers.

No idea, I just put them in because I had them laying around.

Will definitely be upgrading to 21"s at some point but I can build 2 more boxes with the same drivers for basically no money, still use my current amp and have nicer bass than any other amateur outdoor system in my area, and easily outplay any but the biggest nightclub in my city if I decide to do another indoor party.

I'm away interstate at the moment but I need to drag them out for a beach party next week so il do some measuring with REW and UMIK1 and post results then. 

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13 hours ago, chrapladm said:

 Do you have the T/S parameters for your 10's or better yet a DATS?

Unfortunately not, they are quite old now and I've lost the boxes and paperwork that came with them, the website only has the specs from the 2017 model onwards which is the series after these so I'm not sure how much different they are (I'd expect they're close but probably not close enough for an accurate model) 

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On 12/15/2020 at 8:32 AM, Ricci said:

Whatever works...LOL! No judgment here. 

 

Finally got around to doing some measurements, I'm no expert but here's what I've got so far.

1 sub in the back yard, running off 1 channel of an EV Q1212 at 8 ohms (havnt measured gains or anything yet, just sitting on what sounded good at my last party). UMIK-1  sitting 1 meter from the front, both flat on the grass (UMIK on the stand it came with)

The green line is no crossovers, just straight from my PC, through the aux jack into a pioneer DJM2000 mixer, then RCA to Mosconi 6to8 DSP and then RCA>XLR into the EV.

The orange line is what I ran at the last party, 2x 80hz 12db LR filters in the Mosconi 6to8.

1/48th smoothing on REW

Sorry about the dodgy phone pics

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RCA, yikes. Graph's looking good! I'd suggest placing a Butterworth 4th order high pass at ~30-35Hz for driver protection and maybe taming that hump down there as well. From the looks of it, you're probably running an acoustic crossover of 120HZ or higher because of that hump at the top. You can use REW to EQ the graph (PEQ like 98Hz -10db Q4 or so), which will clean that up if you add that point to your dsp.

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Had my next party on Sunday on the beach with my 2x skrams and 2x Martin W3 tops running from an inverter in my Prius from 2pm till nearly 2am, averaged around 1000w into the whole system (including the CDJs and amps and a few LED lights) and used about 5L of fuel in the car.
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Around 150 people at the peak of the dancefloor, everyone seemed to love it!
Definitely need to build 2 more of these things and upgrade to the proper drivers for even better sensitivity to keep up with the tops
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Hey @h3idrun looks like you got decent results.  You could try power compression (see testing methods on this site) testing to see how close your actually getting to a 21" (Sweeps increasing in level until your getting 3dB compression).    The umik-1 tops out around 120dB so if you will probably need to move it back a few meters to reduce the level.  I like the idea of running the Prius as a generator.  I have a 6 channel DSP amp box running off a 16S lithium battery I built for portable stuff.

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Hey Josh. Curious if you would be willing to make a recommendation for high and low pass filters with recommended slopes your Skram design. It’s been a while since I’ve had mine out with the pandemic and all, but I’m planning a day at our studio tomorrow to get everything plugged in and spend some timing tuning and tweaking. Planning to get the measurement mic out and spend some time dialing in the system so I don’t get rusty haha. I’ve been happy with the setting I’ve been running which I don’t remember off hand but I’ve got some different amps on hand so willing to try some new things. Another goal for tomorrow is to try and get some comparison data between the Cvr 3002’s and the powersoft k-10. 

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Does anyone have a hookup for a place in Australia that sells drivers that suit these, or an American company that wont charge separate shipping on each one? I'm almost ready to upgrade to some 21s and they're all outrageously expensive to get to Australia

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4 hours ago, h3idrun said:

Does anyone have a hookup for a place in Australia that sells drivers that suit these, or an American company that wont charge separate shipping on each one? I'm almost ready to upgrade to some 21s and they're all outrageously expensive to get to Australia

Are you wanting BC drivers and where are you located at?

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On 1/3/2021 at 7:01 PM, chrapladm said:

Are you wanting BC drivers and where are you located at?

The 21DS115-4's would be ideal, but any of the other drivers that suit these would also work. I'm in Adelaide and have a friend in Melbourne building some of these also, the cheapest we can find so far is Parts Express ebay site

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I'm in Adelaide. I have a pair of 21SW152's sitting on a shelf still waiting for me to build my Skrams. As long as you dont mind the long wait for shipping times there are better options that PE. But if you want it asap then PE is probably your best option.

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On 12/30/2020 at 7:47 PM, jay michael said:

Hey Josh. Curious if you would be willing to make a recommendation for high and low pass filters with recommended slopes your Skram design. It’s been a while since I’ve had mine out with the pandemic and all, but I’m planning a day at our studio tomorrow to get everything plugged in and spend some timing tuning and tweaking. Planning to get the measurement mic out and spend some time dialing in the system so I don’t get rusty haha. I’ve been happy with the setting I’ve been running which I don’t remember off hand but I’ve got some different amps on hand so willing to try some new things. Another goal for tomorrow is to try and get some comparison data between the Cvr 3002’s and the powersoft k-10. 

I'm pretty sure I posted some rough starting filters somewhere in this thread. I'll have to try and find them. 

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10 minutes ago, Ricci said:

I'm pretty sure I posted some rough starting filters somewhere in this thread. I'll have to try and find them. 

No stress, I can dig through it again. I did play around again a bit over the last week and I think to my ears at least I still like 100 to 110 hz crossover for most music styles. If I drop it down to 80-90 I think it sounds a bit better for stricktly bass music, but for house and techno, rock etc I prefer it a bit higher. Then again its harder hearing it proper indoors. Depending on our pandemic situation when summer rolls around I'm pretty keen on heading out to crown land for a number of days just to work on tuning.

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Ok. I had a look in HR. It had been awhile. 

I'd recommend a 3rd order BW at 24Hz or a 4th order LR HPF at 21Hz. This is for operation with all vents open. 

4th order LPF adjusted to taste for blending with the mains. Somewhere between 50-120Hz. 70-100Hz is probably what would work for most. 

The response looks quite good with just the high and low pass added. 

This is the response with the 21SW152-4. Most of the other recommended drivers are going to be close to this as well. 

SKRAM 21sw152-4 Filters.png

 

If you want to take it a bit further You can add a single band of PEQ at about 195Hz to beat down the first out of band response spike. This would be best if measured and tweaked accordingly but as a start these specs are probably close enough for gov't work. 

SKRAM 21sw152-4 EQ Filter.png

 

This would be the final with the HP, LP and single band of cut EQ up top. 

SKRAM 21sw152-4 LR Filters + EQ.png

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33 minutes ago, Ricci said:

Ok. I had a look in HR. It had been awhile. 

I'd recommend a 3rd order BW at 24Hz or a 4th order LR HPF at 21Hz. This is for operation with all vents open. 

4th order LPF adjusted to taste for blending with the mains. Somewhere between 50-120Hz. 70-100Hz is probably what would work for most. 

The response looks quite good with just the high and low pass added. 

This is the response with the 21SW152-4. Most of the other recommended drivers are going to be close to this as well. 

SKRAM 21sw152-4 Filters.png

 

If you want to take it a bit further You can add a single band of PEQ at about 195Hz to beat down the first out of band response spike. This would be best if measured and tweaked accordingly but as a start these specs are probably close enough for gov't work. 

SKRAM 21sw152-4 EQ Filter.png

 

This would be the final with the HP, LP and single band of cut EQ up top. 

SKRAM 21sw152-4 LR Filters + EQ.png

This is amazing, thanks Josh. Looks like I can open mine up to go a bit lower than what I had been doing previously. Thank you!

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19 hours ago, jay michael said:

No stress, I can dig through it again. I did play around again a bit over the last week and I think to my ears at least I still like 100 to 110 hz crossover for most music styles. If I drop it down to 80-90 I think it sounds a bit better for stricktly bass music, but for house and techno, rock etc I prefer it a bit higher. Then again its harder hearing it proper indoors. Depending on our pandemic situation when summer rolls around I'm pretty keen on heading out to crown land for a number of days just to work on tuning.

This is pretty close to my findings too, I ran 80hz on bass music and 100hz on house/techno, I'll probably try 110hz next time for a little more punch. 12db LR for both, I haven't needed a high pass yet as I've running bugger all power so far.

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