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Ricci's Skram Subwoofer & Files


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20 hours ago, SME said:

I've always regarded MDF to be heavier than BB plywood, so I decided to try looking it up:

https://www.inchcalculator com/how-much-does-plywood-weigh/

Different products will vary a bit, but the chart there suggests BB is only about 70% as heavy as MDF.  I do agree that BB plywood is stronger and more durable than MDF.  There are other pros and cons.  MDF is more messy and toxic to work with (dust) but also a but more forgiving.  MDF has more adhesives which may improve its damping properties.  Many speaker makers argue that the damping properties of MDF make it superior to BB despite the lower stiffness-to-mass ratio.

My thought is that MDF is OK for things that don't get moved/transported a lot and where weight is not important.  For big subs that get moved around a lot, MDF is not a good idea.

If BB plywood is exceedingly expensive in AU/NZ perhaps look for another high quality hardwood plywood product.  As I noted above, BB tends to have thinner plies than other types.  Another benefit of BB plywood over other stuff is that it tends to be void free.  (Tends to---alas the last stock I bought still has a few small gaps :()

 

I will agree to pretty much everywhere here.

BB is nice for things that get big, even if you don't move it much. When you do need to move it (and you will) you won't regret the BB. 

 

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BB holds screws better as well. In general I avoid MDF or HDF when possible, especially on larger cab sizes. For things like small monitors and car subs it isn't a bad choice to save some money. 

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I've built subs out of cheaper hardwood ply and MDF before.  The cheaper ply works but is more vulnerable to damage than BB ply,  this can to an extent be made up for by rounding (and filling if there are voids) the corners and using a tough coating. MDF is horrible to work with, heavy and vulnerable to damage at any exposed edge.  I would use cheaper ply rather than MDF.  I don't use screws I use a brad nail gun and glue, this way you can build a cab very quickly!

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  • 4 weeks later...
On 3/27/2021 at 6:52 AM, jay michael said:

Blowing out the cobwebs today 

 

Is this total stack under 10ft?

 

Trying to figure out what sort of combo I am going to attempt for myself. Divorce is about finished and I will finally be able to build some speakers finally.

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6 hours ago, chrapladm said:

Is this total stack under 10ft?

 

Trying to figure out what sort of combo I am going to attempt for myself. Divorce is about finished and I will finally be able to build some speakers finally.

Its under 10 feet. I'm 6 foot, so in total the stack is about 9'ish I would say 

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Hello all. After reading a lot I have made the dicision to build 4 skrams. 

Was using 2 keystones (sw115) and hoping te 4 skams wil make me more happy.

So what is unclear for me is the best driver choice,, and maby one of you could point me in the good direction.

My amp is an x8 Powersoft of witch I have 2 channels avedible for running the 4 skrams, note that the other 6 channels are barley loaded (4x pm60 tops) so there wil be quite a lot of powershearing able to go to the 2 sub channels.

I would like to get as mutch as possible out if the 4 Skram and my amp. combination, sinds I am really restricted in space and transport to go bigger on the number of subs.

From B&C what would be my best choice between the 21. DS, SW, or Ipal, and don't mind the difference in price for this comparison. Just would like to hear from someone how is better able the me to make the choice between this 3 drivers in combination wit my avadible 2 ampchannels

And thanx for al the info and knowledge I have been getting form reading here in this forum!

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https://www.powersoft.com/wp-content/uploads/2018/04/Powersoft_X8_DS_EN_WEB.pdf

So you have the choice of running the two channels bridged or as non bridged channels.  Bridged is rated down to 4 ohms so you can't run all 4 drivers off this.  Then looking at single channels maximum rated  power is at 2ohms per channel so you should put two 4 ohm coil drivers on each channel.  This excludes the IPAL leaving the SW or DS, the DS has a more powerful motor and slightly higher XVAR so should be capable of more output.

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Greetings!
After listening to "Skram" for a long time(3mon), I can say that the box works very nicely and controls the speaker very well .. I tried to put it inside B&C 21DS115-8 // B&C21SW152-8 // RCF 21N551-8
I am currently using Rcf and staying with it because it is raw and tight, and the overall performance is better , better spread over octaves than with two b&c SW152 is deeper and stronger but therefore more muddy or undefined, ds115 sounds even more beautiful to me in terms of softness and bass, but it lacks "strength" compared to these two before ..

 

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Thanx guys, for you reply,s 

I would like to sim them, and just to be sure in comparing appels to apples. Dos any of you have driver files to import in HR, witch have the corrected inductions, as I don't understand sure how I can correct this myself.

for B&C 21DS115-4, B&C21SW152-4, RCF 21N551-4, Eminence NSW6021-6

Also I can get 4 Ipal on 1ohm used for a very good price. To Ricci, would you still prefer the Eminence NSW6021-6 to the Ipal 1ohm 2x serial on a x8 channel.

Is this HR data the best one to use to date?

311013417_Skram21SW152-4inputs.jpg.60dff

Its from July 16, 2019.

As I went couple times trough the whole thread,, its starting to dazzle a bit but I am super exited to start the project!!

greetz

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10 hours ago, ChikoRomantiko said:

Greetings!
After listening to "Skram" for a long time(3mon), I can say that the box works very nicely and controls the speaker very well .. I tried to put it inside B&C 21DS115-8 // B&C21SW152-8 // RCF 21N551-8
I am currently using Rcf and staying with it because it is raw and tight, and the overall performance is better , better spread over octaves than with two b&c SW152 is deeper and stronger but therefore more muddy or undefined, ds115 sounds even more beautiful to me in terms of softness and bass, but it lacks "strength" compared to these two before ..

 

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hi Choko, I could not make clear out of your poosts if you use them at home or PA purpose. 

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Jordy,

The 21Ipal is good as well but if you ever want to run a single cab it will be hard to find an amplifier that likes the 1ohm load. If you have a good price on 4 and the impedance will work for you go ahead. 

The semi inductance for some of the drivers that you listed are shown on the driver testing page on the main DB website. 

Yes that HR input is the current "best" match at least until I can get a cab tested. 

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On 4/8/2021 at 6:08 PM, jordy said:

hi Choko, I could not make clear out of your poosts if you use them at home or PA purpose. 

As for the speakers I used b&c 21sw152 is more beastly but to me personally ds115 is much more tonal sounds nicer and softer in lower frequencies .. why I chose rcf because it is sharper, much more aggressive about 60hz than all the others, and if I put 4 the skram will go deep enough to cover that small flaw that it has unlike these two .. if we look at the PA purpose and the sound to me personally of these three rcf is the one that meets my needs.

I use them primarily for my own pleasure: D hehe
for PA purposes, I have my own sound system DIY (DUB / Bass music) and also work for rental company .. I put two Skram with rcf speakers inside connected to the k10 with DSP (but48_30HZ-65HZ_but30) main purpose, because we also have a bass section with which I cover most of it (270hz) :) ...
I also used skram of 30-110 hz with RCF HDL 26A and they work really really nicely !!
with 4 scrams covering 500 people concert for sure!

unfortunately I haven't played with port tuning yet and I also haven't dumped the skram with anything inside, meaning just a speaker and bare wood!

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On 4/14/2021 at 5:24 PM, Ricci said:

Chiko,

I'd suggest putting some damping in there behind the drivers. It should clean up the top end a bit and "tighten" the sound. 

Thank you, know i need since i read about skhorn.. we don't have money at the moment as we want to do everything in one purchase (handles, connectors, paint for those and others  boxes and some other things like protective angles etc ..) also think i will close two ports and see outcoming as the main purpouse of the Skram will be 30 - 65Hz
can’t wait for a little warmer weather to take the whole sound out and test it properly!
We need to make two more Skram and a party in the village : D

Ricci what do you think about Paraflex C-2E 1x21 ? 

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  • 3 weeks later...

Spent a full weekend ripping wood for a pair of cabinets. Plan is to augment or eventually replace a pair of Keystones. I've always been a TH fanboy but I trust that if Ricci thinks bandpass cabs are the business then I'm eager to give it a go. Looking forward to that sweet 30hz.

USER_SCOPED_TEMP_DATA_MSGR_PHOTO_FOR_UPLOAD_1619991865250_6794738360388002482.thumb.jpeg.d9a361c898cab20892696ad360a1bf13.jpeg

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On 2/26/2021 at 9:39 PM, MomoTon said:

I don't know if you saw my skram built on page 26 or so, I built 2 of them, made of popplar plywood with a carbon-epoxy layer around to make it stiffer. Then we made the front out of 25mm transparent acryl glass, just to loose the weight savings due to the 10kg (just a wild gues, I forgott the real numbers) of those fronts haha. We didn't put them on a weighting scale yet, but without the heavy front, they would be ridiculously light! So light that we will make a base filled with sand to make sure they dont move more than the drivers do.

 

I'm interested in this popplar plywood carbon-epoxy layer construction, do you have any details of the products used?

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  • 2 weeks later...

kipman, we bought the epoxy and carbon fibre on a german website, "HP-Textiles". 

Important is to not use the classic fibric mesh for the good look, but the one where the carbon fibres are just laid and needled together.

We tried different epoxy systems, but both, the one especially for laminating, but also the universal did a good job, if you know how to do the job haha

 

Unfortunately, we still didn't finish our subs, so we dont't even know if all the work brought also some improvements except the weight savings, hopefully we know it in some weeks...

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  • 4 weeks later...

195772362_888547628361700_2734423695556742577_n.jpg.bff506c873f5daff2886c84d96de6171.jpgSome carpentry sins have been committed due to time constraints and lack of both quality tools and experience, but nothing I don't expect PL and Bondo to hide. It's an intimidating build to do by hand, mostly due to the bracing, but I wanted to do it "right" and I expect the cabinet is going to be stiff as hell. Got some 21DS115-4s on deck and if all goes well they'll be at full flex at an event last weekend in June.

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