Ricci's Skram Subwoofer & Files

[rolo95]

16 hours ago, peniku8 said:

1. the LaVoce is a perfectly adequate driver. If you're in the US, the Eminence driver will output like 2dB more. In Europe the price difference doesn't make any sense

2. a roundover bit

3. I machine circles in the top of the cabinet where the (round) feet sink into

4. uh none; you can line the walls not near the port with foam if you like

5. you answered your own question

6. that's up to how good your woodworking skills are - I built an SKhorn without a cnc

1. the LaVoce is a perfectly adequate driver. If you're in the US, the Eminence driver will output like 2dB more. In Europe the price difference doesn't make any sense

yes i am in the US, you mean the 1,200 USD eminence ? the 21ds115 are around 780 around here but the Lavoce is less than that.

2. a roundover bit

i am new to woodworking, any links to that bit ?

3. I machine circles in the top of the cabinet where the (round) feet sink into

what do you use to made those and how do you align them perfect

4. uh none; you can line the walls not near the port with foam if you like

is there any before and after graphs of response , or somebody who heard the difference if any

5. you answered your own question

lol, what i meant is  a 4 channel amp driving 4 skrams with the 21ds115-4 , one cabinet per channel 

versus 2 channel amp driving 2 cabinets loaded with the 21ds115-8 per channel.

6. that's up to how good your woodworking skills are - I built an SKhorn without a cnc

my skills are non existent, i want to learn and start making sawdust but i guess i need to start with simple boxes with scrap lumber, until i can do exact cuts i can start butching the expensive ply   , what guides or tutorials you recommend to watch so i can start my woodbutcher journey.

[klipsch]

YouTube or your choice video feed will help. Start with understanding how to rip sheets of ply and using a plunge router. 

You'll want to invest in a lot of clamps.  A quality surface area to enable precision and comfort will go a long way as well. 

[rolo95]

Deleted

 

 

[h3idrun]

If you've got no woodworking skills this is a pretty ambitious project to start on, maybe make a book shelf or something first to get your head around using saw and router and clamps. Or even a work bench to then build your speakers on.

[Domme]

It's no easy project at all. I have some woodworking experience, but not too much, and had some help from a friend master carpenter and it was still a PITA to get it all right. Without his help I probably would have messed up the glue step because you need to be quick! Those huge surfaces are not easy to move around once you apply glue and it's almost the last step and you can still mess everything up... you also need strong clamps and MANY of them.

I would probably order all parts CNC'ed next time because even though it was worth for the experience and learning, when you count man hours it wasn't worth spending hundreds of hours just to save a bit of money. Anyway, good luck!

[peniku8]

25 minutes ago, Domme said:

It's no easy project at all. I have some woodworking experience, but not too much, and had some help from a friend master carpenter and it was still a PITA to get it all right. Without his help I probably would have messed up the glue step because you need to be quick! Those huge surfaces are not easy to move around once you apply glue and it's almost the last step and you can still mess everything up... you also need strong clamps and MANY of them.

I would probably order all parts CNC'ed next time because even though it was worth for the experience and learning, when you count man hours it wasn't worth spending hundreds of hours just to save a bit of money. Anyway, good luck!

If you have an air compressor, buying a brad-nail gun is a better investment than buying clamps imo and it makes building the cab way easier.

If your cuts are clean and you don't have to use construction glue, that is the best solution. Danley does it like that. If I didn't buy a large press to put the whole speakers into, I'd do the same.

If you really want to use clamps, I can recommend to buy extruded aluminium to spread the clamping force over the length of the edges like I did in my Bordeaux build:

[zenbass]

Ricci, I would love to send money for plans to the skram!

[Victor]

One more happy builder of this excellent design! Going to make another when time permits.



I bought the drivers from China, for $450 + shipping. The TS parameters:

Ningbo Vejoworks Technology Co., Ltd
MODEL PR21SW150
coil winding height 48mm
top plate 18mm
XMAX ~15-21mm
Fs 28.3
Diameter 460.0000
Re 2.2
Z 4ohm
Rms 18.8 (calculated)
Qms 3.783
Qes 0.165
Qts 0.158
Cms 0.090
Mms 393.137
Mmd 352.897
BL 30.555
Vas 328.388
dBSPL 98.4
SD 1698.23

 

 

[chrapladm]

Were you able to measure the T/S parameters for your driver with a DATS or something? Or at least measure the impedance and response on finished product?

Curious how close their drivers are to their stated T/S. I have a few drivers from China I have bought in the past that are paper weights only. Finished product, cabinets, look great either way.

[Victor]

I'm also not sure how precise are the TS parameter numbers. If I have enough time someday, I may try to measure them. I do have a relatively good measurement microphone so technically it should be doable.
In any case, I'm extremely pleased by the performance and sound quality. In terms of the performance it's in a different league compared to my old 18" sub (on the picture on the left, B&C 18DS115-8)
I do have another such 21" driver and going to build another Skram soon.
I also have a 24 inch driver I bought on Alibaba, and will need to use hornresp to calculate the correct enclosure for it

 

[klipsch]

On 8/3/2023 at 11:41 PM, zenbass said:

Ricci, I would love to send money for plans to the skram!

Plans are in the beginning of this thread. Send Ricci money anyway 

[ste]

THANK YOU for sharing the skram! after making an initial two skrams, i`ve just finished another six. eight skrams in total, loaded with lavoce 214.50 1700W/8ohm
http://www.loudspeakerdatabase.com/LaVoce/SAN214.50

i`m running two channels with four skram cabinets each at two ohms from a single crest pro9200, 8sqmm cables

instead of breaking the woofers in freeair i had them broken in last weekend with a live analogue acid tekkno set and tekkno DJ. there was too much sub, so i rolled off at 40Hz which is typical for tekkno sound systems, and reduced my low shelve boosts i use for bassmusic and personal listening preference to 0dB, and everyone was happy with the bass tone.

anyhow... in september i will have D&B and bass music, techno, schranz and an eighties events. these beasts will move alot of air!

next step is making vent shutters, so i can flexibly tune the skrams, an initial test showed promising infrasonic results. the idea is to use a subharmonic syntheseizer so i can fiddle around a bit during the parties. plenty of headroom to tune to the infrasonic...

also i will venture into outdoor cardioid setups now i have enough cabinets. i`m looking for volunteers to haul cabinets.

if i ever have the chance to do outdoor measurements i will post those here as well.

btw. the grey cabinets will still get a finishing paintjob

 

 

 

[peniku8]

Nice! Now you just need to get appropriate amping and the setup will slay.

Btw, it's called "infrasonic" (sound), not "subsonic" (speed)

[ste]

vent tuning lids added to the skrams. dsp settings are LR 24dB at 10Hz. bass is more exciting even at listening levels. fun times.

[Ricci]

Nice build pics STE.

[dpd]

Hello STE, your synergy-like tops are intriguing.

Are they DIY builds? From what plans/source?

[mafosta]

Hello all. I'm new here, but have been aware of the Skram for some time. I'm wondering what the potential is for a miniaturized version for a 15" driver, such as the Ciare 15.00SW-4.

Ricci, does this sound interesting or feasible? It may be a nice option for people with smaller applications, maybe even for home use. Just a thought. Thanks for all your excellent work! 

[chrapladm]

On 9/5/2023 at 1:41 PM, mafosta said:

Hello all. I'm new here, but have been aware of the Skram for some time. I'm wondering what the potential is for a miniaturized version for a 15" driver, such as the Ciare 15.00SW-4.

Ricci, does this sound interesting or feasible? It may be a nice option for people with smaller applications, maybe even for home use. Just a thought. Thanks for all your excellent work! 

There are a LOT of other designs that use a 15" driver. Also not sure the Ciare is any good in any of the TH, FLH or Hybrid designs that I can think of.

[ste]

On 9/1/2023 at 8:20 PM, dpd said:

Hello STE, your synergy-like tops are intriguing.

Are they DIY builds? From what plans/source?

they are designed by a friend, inspired by the syntrip and of course synergy. the dcx464 driver makes a very low xover to the 12" woofers possible, what makes this specific design possible. its a 60x90 horn.

[ste]

tried out 8 skrams cardioid outside setup, cancelling in the back was incredible. also the beam was very narrow, perfect for the situation. walking in and out of a zone of massive bass adds to the overall experience of the guests as well. i followed the MichaelCurtisAudio instructions for this setup and they worked like a charm. crossover was a bit higher at 100Hz ato go a bit more relaxed on the tops, and the skrams punch in the higher bass as much as the kick in the lower.

also i was wondering how it makes a difference to stack the subs with the openings closer to each other compared to what we did, when the wavelengths are so long. i didn't notice anything weird the way we stacked them. i even considered stacking the top ones upside down, to space the stack. wouldn't that improve the beam pattern even more?

we had no time for measurements.

the skrams produce a super dry bass, ludicrous levels achievable even with a lesser efficient cardioid setup like we did. my guess is you could have a 1000 people audience with 8 skrams. (these are IPAL ready, just imagine the output!)

two skrams fit on a europallet, a skram is possible to stack with two guys, the height of two skrams is perfect to stack a top on... they fit through any standard door, the driver is savely protected and a splash of beer won't do any damage either. a very convenient design.

[peniku8]

Nice endfire setup! I'm in the process of building a 4th sub (not Skram but also 21") and will bring all 4 to a wedding next month. I also got a mail from CVR that they released a new 35KW 1U amp. Would love to test it but can't really justify buying stuff just for fun yet lol!

[DJimbo]

Awesome shares yall.

I spoke with a rep of B&C about powering their drivers. Guy was insanely knowledgable. He said, "you want the absolute most powerful amps that are made to power these drivers properly"

He explained how power hungry these can be and how under-driving them is a bad idea. We discussed powersoft amps and Linea. He basically just shot down my dreams of being able to power these (6 or 8 SKRAMS) properly off of a 120v circuit, or even two circuits. Now I am a lamen when it comes to most of this so I am curious about yall's thoughts about this.

Like 21' drivers are sick obviously but if we are putting them in such a small box for their size we are cutting their balls off a bit. I guess I am stuck wondering if the LF extension of the skram is worth the extra amp expenses, powering issues, etc. when TH118XL's can be found used and are comparable in size and output (above low low freq's) according to previous posters. Id love to be enlightened on the skrams and anything I am missing here and I think our group here will find any reflections useful. Thanks!

[jay michael]

32 minutes ago, DJimbo said:

Awesome shares yall.

I spoke with a rep of B&C about powering their drivers. Guy was insanely knowledgable. He said, "you want the absolute most powerful amps that are made to power these drivers properly"

He explained how power hungry these can be and how under-driving them is a bad idea. We discussed powersoft amps and Linea. He basically just shot down my dreams of being able to power these (6 or 8 SKRAMS) properly off of a 120v circuit, or even two circuits. Now I am a lamen when it comes to most of this so I am curious about yall's thoughts about this.

Like 21' drivers are sick obviously but if we are putting them in such a small box for their size we are cutting their balls off a bit. I guess I am stuck wondering if the LF extension of the skram is worth the extra amp expenses, powering issues, etc. when TH118XL's can be found used and are comparable in size and output (above low low freq's) according to previous posters. Id love to be enlightened on the skrams and anything I am missing here and I think our group here will find any reflections useful. Thanks!

Thankfully we live in the times of cheap and plentiful amplifier power. If you can manage without sophisticated control and monitoring you can find lots of options for  amplifiers that can easily turn these drivers into molten lava. Take a look at companies like Admark, Cvr, Wasi just to name a few. For as little as 8 or 9 hundred usd you can get 15kilowatt 2 channels amps that can push their rated power into long sustained loads and sound great doing it with solid reliability. Pick yourself up a nice dsp from Linea Research,  or one of the other leading brands and get a few of these amps and you will be loving it. Even on a 120 circuit you should be able to properly power 2 or 3 skrams without tripping breakers. These amps conveniently have power factor correction, so they will take what ever voltage you throw at them reliably

 

[chrapladm]

14 hours ago, peniku8 said:

...............I also got a mail from CVR that they released a new 35KW 1U amp.............

Where can I find out more info on this said device?

[peniku8]

20 hours ago, jay michael said:

These amps conveniently have power factor correction, so they will take what ever voltage you throw at them reliably

I was under the impression that the variable input voltage thing was a doing of the SMPS itself, not PFC. Are you sure these amps have PFC?

12 hours ago, chrapladm said:

Where can I find out more info on this said device?

I got an email from them announcing the D-3004 with 4x8600W@2Ohm but in the follow up mail their rep said that the amp isn't really 2Ohm stable lol. But if it really performs up to spec, you could run 3 Skrams per channel for a total of 12 cabs off of a 1U amp, which would be pretty sick. But of course pushing the amp pretty hard.