This winter's DIY-project just arrived.

Re: This winter's DIY-project just arrived.

I have read all the info i could find as soon as it was released.
I know that the software can adjust the TS parameters to some extent and with that get the maximum possible out of the driver box combo. The sensor helps in getting the max performance but be safe at the same time. So that is all fine.
I have done tons of simulations and the results were impressive up to the point where you put 8 ohm as a impedance. Then rolls back very close to 21SW152.
So i take it as a 1 ohm 21SW152 with very precise control from the power amp.
But, since i was not impressed with the 21SW152 during my tests i have abandoned the idea to go Ipal route.
All this does not mean that it is not good, it just didnt do what i wanted to do.
 
Re: This winter's DIY-project just arrived.

Just for the sake of comparison I have used the same box size and tunning and plotted max SPL based on Xmax.

With 8500w available with the IPAL module you would probably use a different tuning and box volume.

Note : Win ISD assumes the IPAL is 2 ohms, not 1 ohm, accordingly the power specified may be wrong ... you may only need 8000 watts to do that ...don't know.
 

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Re: This winter's DIY-project just arrived.

I use customized 18NLW9601. Bigger box, like 500lit outside volume.
Now you get my point. With same power applied to a 2x18 and the IPAL21 there would be no advantage at all.
With double the power you have less then 2db advantage. 2x18 is much faster sounding (better impact) and still goes low enough.
For infra use i would definitely use the IPAL21. But for one box bass solution i dont like it. It is possibly a mater of taste, so your mileage might vary.

BTW is 4800W for 2x9601 for both drivers total? I see you use same 4800W in both single and doube box.
 
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Re: This winter's DIY-project just arrived.

Marjan Milosevic said:
I use customized 18NLW9601. Bigger box, like 500lit outside volume.
Now you get my point. With same power applied to a 2x18 and the IPAL21 there would be no advantage at all.
With double the power you have less then 2db advantage. 2x18 is much faster sounding (better impact) and still goes low enough.
For infra use i would definitely use the IPAL21. But for one box bass solution i dont like it. It is possibly a mater of taste, so your mileage might vary.

BTW is 4800W for 2x9601 for both drivers total? I see you use same 4800W in both single and doube box.
Click to expand...

Ooops - 2400 for a single ... have fixed it Thx.

I look at the 21IPAL and matching amplifier including the pressure senor / feedback loop as a complete system. As a system it should produce tight bass, go low loud and low – but I have never heard one.

I don’t compare it in terms of amplifier power … just $$, output & size. With 22mm of Xmax it should be capable of 3 dB more LF than just about anything else.

If you look at the driver in isolation then it doesn’t really add up for me. Your double 18 with the 9601s(var) or mine with the 9000s is an excellent compromise. The 18SW115 also would be excellent choice ... but the LF power per cubic metre offered by the IPAL ....:)~:-)~:smile::)~:-)~:smile:
 
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Re: This winter's DIY-project just arrived.

Helge Dr. Bentsen said:
Finally got a deal settled with a CNC-shop, they are making the pieces for four of Art's Keystone subs modified with a larger driver cutout to fit a 21".
Click to expand...
Hope to hear about some ground shaking going on soon!

Will be interesting to hear how you find they compare to the LABs, have a feeling there will be some for sale in Norway shortly ;^).
 
Re: This winter's DIY-project just arrived.

Marjan Milosevic said:
Size is the biggest advantage. No question about that. Price.... hmm is roughly about 4 18NLW9601 for one IPAL21.
Click to expand...

Hi Marjan,

Perhaps you have different pricing than we do here in the USA, always hard to compare between brands. On Amazon, where both the 21IPAL and 18NLW9601 are available, the 21IPAL costs nearly exactly as much as two of them. On our price sheet it's about the same price as two 18SW115.

The IPAL system is designed to be a "powered woofer", and cannot be considered on its own without a powerful amplifier that can provide equalization. It is a compromise to create a transducer that models and measures well without processing, so we have made one that is intended to be processed. Knowing the tools available means a better final result can be created. Considering the 21IPAL has 4Kg of high-grade Nd in the magnet structure and over 1.4T in the gap, as well as high power handing and excursion, it is unlike any other woofer I am aware of.

I humbly suggest you try one in the real world, outside of simulation. The IPAL is not perfect for every situation, but was designed to meet maximum output for physical space for truck packing efficiency. It cannot be compared to the 21SW152.
 
Re: This winter's DIY-project just arrived.

Some pictures from the CNC shop.

Bennett: I haven't got around to order amp modules yet, but I have a Powersoft K20 DSP. Can it be used for testing without fear of damaging the drivers?
 

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Re: This winter's DIY-project just arrived.

Helge Dr. Bentsen said:
Bennett: I haven't got around to order amp modules yet, but I have a Powersoft K20 DSP. Can it be used for testing without fear of damaging the drivers?
Click to expand...
Hi Helge,

I don't know why it would damage the drivers, any more than any other amp. Probably the amp won't be harmed, and at the frequencies you're likely to use it the impedance will be much higher than 1Ω anyway so I imagine it will drive the woofer just fine. Set the fancy pants power limiter in the amp to 1/2 AES power and if the woofer (or your house!) starts making funny noises turn it down!

P.S. We use a MacroTech 5002VZ to take our Klippel data, and it's nowhere near enough to drive this woofer into really bad behavior. Pretty funny that yesterday's big boy amp is now so "wimpy".
 
Re: This winter's DIY-project just arrived.

Helge Dr. Bentsen said:
Some pictures from the CNC shop.

Bennett: I haven't got around to order amp modules yet, but I have a Powersoft K20 DSP. Can it be used for testing without fear of damaging the drivers?
Click to expand...
Helge,

The .7 ohm minimum impedance of the driver at Fb in the Keystone may put the amp into current limiting, which could "suck".
With 9000 watts available at 2 ohms, you may be better off putting a pair of cabinets in series. 4500 watts peak per unit should be adequate, almost equal to the 21IPal 5000 watt "continuous" rating.
Remember that sine waves have 3dB more average power than the 6 dB crest factor signal used for the 2500 watt rating, which is only 41.83 volts at the minimum impedance of .7 ohms. Sine wave testing at that voltage should be limited to only a few seconds. That said, I put 120 volts 60 Hz sine wave into my 18SW115-4 three times for about a second each time with no problems before I figured out I was turning down the mid, rather than the low output...

Use a 3/8" roundover bit on all internal bends and the Keystone exit both sides.

Assuming Peter's sims were using using Xmax of 22mm, rather than the Xvar of 15mm, I'd expect peak output to be about 2.6 dB less at around 10% distortion.

I wish I were there to hear these!

Art
 
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Re: This winter's DIY-project just arrived.

One more thing: Nails or screws in addition to glue?
I have always used screws on my speaker builds, but I inherited a nailgun from a friend and I'm thinking about using it instead. I use a expanding Polyurethane glue that fills any cracks/joints pretty good.
 
Re: This winter's DIY-project just arrived.

When I built my keystones like 2 months ago I used only 90° cuts, polyurethane glue for the two joints in the horn fold(not the bottom one) and regular glue for the rest. No screws only nails. Seem to work good. I'm not too keen overdoing or overcomplicating things(which is why I chose to try the keystone to begin with) and you can easily knock out one cab in a day if you are effective.

I tried them... loaded with 18sw115 is impressive! Very loud and very clean and the extension works well for edm, I had to cross them at 75-80 or they started to sound a bit barky tho, any suggestions how to make it deliver a bit more neutral sounding kick?
 
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Re: This winter's DIY-project just arrived.

Helge Dr. Bentsen said:
One more thing: Nails or screws in addition to glue?
.
Click to expand...
You need BOTH glue AND mechanical fasteners. In many cases screws AND nails.

While good glue is strong-it is ONLY as strong as the layer it is attached to . Once that layers comes off-the glue is worthless.

Screws are used to pull the cabinet together good.

Staples or air nails are used to provide additional support. The coating on the air fasteners melts due to the friction when going in. It then hardens for additional gripping.

Also the nails/staples should be put in at alternating angles so if the different pieces of wood try to come apart-they have to pull against 2 different angles.

All of these make for a stronger cabinet.

Also using dados and rabbets make for a much stronger cabinet in several ways. They provide a larger glue area and provide physical "stops" (at least in some directions) to keep the pieces from moving around.

It is real easy to build a simple cabinet that is thrown together. Quite another (in time and materials) to build one that will hold up over time and lots of abuse.
 
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