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Ricci's Skram Subwoofer & Files

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On 9/30/2019 at 9:59 PM, menace said:

What do people think about speaker grills for these? It would seem they would alter the tuning some? Any thoughts?

In my SKhorn XLs I put them on the inside, to keep the design . They are absolutely needed in pro use, I found anything from sweaters, bottles, shoes, screws to napkins, purses and all kind of things inside 

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Ah in side the box further down the port/horns. That sounds like quite a good idea as wouldnt need to bother with asthetics and it leaves the mouths to be used as handles.... I'll give that some thought....

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Hey again!

We just found a cheap way to buy the 21ipal and a ipalmod for each skram, so we want to make the skram active.
In addition to that we will plan an active cooling system for the magnet (because we think that temperature will be the a limiting aspect(?)).
Now we are considering to optimize the skram cabinet, because if the temperature and power are not the limiting aspects it will be excursion again, right?
If it's like that, how would you change the cabinet? Maybe smaller, that there is more pressure? Or could be the half skhorn the better option?

Next topic will be the positioning of the pressure sensor of the ipalmod. In the picture there are the possibilities we are thinking of and another picture how 18sound made the positioning (the small hole between the speakers).
It's important that the distance between sensor and diaphragm is as little as possible and it has to measure the pressure difference between the environment in front of the speaker and the back.. 
Has someone experience with the module and the sensor?
Or how would you do it?


 


 

 

skram_pressuresensor_pos.jpg

Bildschirmfoto 2019-10-02 um 12.47.49.png

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Timon.

I am interested in your cheap source for ipal and mod?

Active cooling, does the lag between coil/air/magnet allow this to be practical?

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Ipal on bluearan in uk and the mod from powersoft europe

We don't know if the temperature will be a problem, but if it does we will test some cooling systems (we thought of a water cooling.. )



 


 

 

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15 minutes ago, Timon said:

Ipal on bluearan in uk and the mod from powersoft europe

We don't know if the temperature will be a problem, but if it does we will test some cooling systems (we thought of a water cooling.. )



 


 

 

how much is the mod?

I can't help but think if the water cooling was a thing then they would be offering a solution them selves(powersoft/b&c)?

And how did you go about contacting powersoft directly for this? They have quite a few OEM things that are pretty interesting!

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about 1200€
I just wrote an email to powersoft oem europe and described who we are.. then they answered that they support us with pleasure.
I don't know if its normal or if we are just lucky.

Yeah, I thought about asking for the price for the M-Force haha looks so cool.
 

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Active driver cooling check out "RC1 soundsystem" and "real horns sound system" real horns are using water cooling for the 8 drivers in the bass horn and also realtime excursion measurement while RC1 have an 'active cooling system' which I think is water cooling.  Tom Danley also has a patent on using a air blower through the pole vent.  The main benefit is long term power handling as the magnet can be kept cool and heat removed from the box.

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What are the options for cooling a driver?  I would suspect cooling the outer circumference of the magnet wouldn't be much help as the heat is created in the coil winding.  What about directing air flow into the screen that covers the core of the magnet?

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Improve collateral heat transfer from the coil directly to the environment instead of coil to magnet assembly. With M-FORCE is really easy, but with a moving coil, it is really complicated. I really like a more open assembly, like those made by the car audio sub manufacturers. DD Z series comes to mind. Add a cooler and you're done! 

I own 2 Ipal modules. They are powerful and really good match for a 21Ipal driver. One could get the other into thermal limit of either one of them , depending on situation. The DPC sensor position has to be in the Apex of the horn

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Also...Consider that you will still need to be wary of very high duty cycle signals over the short term. Things like air and water cooling will help with long term heat buildup in the motor and coil, but not so much with rapid heating of the coil over a short time period. Coils can be burned VERY quickly in some cases with a bad scenario. With that said I wouldn't assume that you will be able to increase the short term peak signal handling of the system at all and this is what has the possibility of reaching driver Xmax for the most part. The longer term signals that make most of the heat buildup aren't normally going to be causing excursion issues. In fact greater excursion helps cool the voice coil and motor. With that said I definitely wouldn't go smaller with the cabinet. 

Ipal module will fit on the hatch. The hatch is the same as on the Skhorn and I believe I posted the files for the hatch with a Speakerpower SP series and the Ipalmod cut out in the Skhorn thread. As mentioned you want the sensor close to the cone and apex of the horn. 

 

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I've asked this before, but I'd like to know if the Beyma 21SW1600ND would be a close match to the cheaper drivers. I can get a pair for 450, and my initial modelling (based on the manufacturers disclosed specs) are great. 

 

Anyone who can chime in? 

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Finished a Skram a couple of weeks ago and I love the sound. My wife even commented on how smooth it sounded. Completely outran my tops. I originally put a driver from zxpc in it since the LaVoce was out of stock. Pretty ugly. Anyway got the LaVoce in and this is what I measured quick and dirty. No reference as to SPL - I used the USB OmniMic but I was running a signal flat from computer to mixer to xover. I think I lowpassed it at 200hz; high pass was off. Actually, not sure where I lowpassed it... somewhere above 100 hz. 

Also, I'm between jobs and would love to sell this to someone. Guess I should post it in the for sale section.

Skram.jpg

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So, Im finally going to start building my SKrams.... my new room is finished and getting all the sub stuff buttoned up.

I have all the pieces CNC'd. Is there a good order to put it together? 

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Mines are almost ready as well, just have to put one more varnish coat, put the driver (21DS115-4) in and measure them !

Will post everything there as soon as I'll have the time to setup everything and when the weather will get better here.

71035327_2634358973296326_7042003527840825344_n.jpg

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Thanks for the good advices!
I´ll be back with some testing results of the materials and maybe we try some cooling systems (not sure yet)
 

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On 10/3/2019 at 5:46 PM, Droogne said:

I've asked this before, but I'd like to know if the Beyma 21SW1600ND would be a close match to the cheaper drivers. I can get a pair for 450, and my initial modelling (based on the manufacturers disclosed specs) are great. 

 

Anyone who can chime in? 

It looks ok based on Beyma's specs. A little light on motor force but should be fine. The unknown is what the complex inductance specs look like but based on the published impedance curve it shouldn't change things too much.

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On 10/2/2019 at 9:06 PM, Ricci said:

Also...Consider that you will still need to be wary of very high duty cycle signals over the short term. Things like air and water cooling will help with long term heat buildup in the motor and coil, but not so much with rapid heating of the coil over a short time period. Coils can be burned VERY quickly in some cases with a bad scenario. With that said I wouldn't assume that you will be able to increase the short term peak signal handling of the system at all and this is what has the possibility of reaching driver Xmax for the most part. The longer term signals that make most of the heat buildup aren't normally going to be causing excursion issues. In fact greater excursion helps cool the voice coil and motor. With that said I definitely wouldn't go smaller with the cabinet. 

 

If this method was implemented the short term power handling would also increase:

https://patents.google.com/patent/US4757547A/en

 

 

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8 hours ago, Ricci said:

It looks ok based on Beyma's specs.

OK, as in equalish to the Lavoce and other cheaper drivers? :)

A little light on motor force but should be fine. The unknown is what the complex inductance specs look like but based on the published impedance curve it shouldn't change things too much.

 

 

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20 hours ago, Droogne said:

OK, as in equalish to the Lavoce and other cheaper drivers?

Based on the specs it should be. I've never seen any 3rd party data on it though which trumps MFG specs IMO.

Unless it is significantly cheaper I'm not sure I'd choose it over one of the Lavoce, B&C or 18 Sound models. If you are getting a great deal by all means give it a shot. 

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On 10/7/2019 at 2:46 AM, Alexlel said:

Mines are almost ready as well, just have to put one more varnish coat, put the driver (21DS115-4) in and measure them !

Will post everything there as soon as I'll have the time to setup everything and when the weather will get better here.

71035327_2634358973296326_7042003527840825344_n.jpg

Looks very nice! 

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18 hours ago, klipsch said:

Looks very nice! 

Thanks!

My first build (the big cuts were done by the carpentry, just had to do the speaker, middle brace and handles holes) and the first drivers I ever bought ahah. The DIY way makes me discover a lot of things!

I like the look they have, the varnish tinted them in yellow, that was a great surprise, it gives them a vintage touch!

My last coat was drying yesterday, hope the weather will be fine next week-end!

 

 

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