NSW 21" or SI HST 18"?

ryanosaur

ryanosaur

Audioholic Warlord
I know nothing about your TC Driver.
*shrugs

The NSW is one of the top Pro Drivers that I've seen DIYers talking about, though. It can be pushed low, with penalties, but it's true purpose is mid bass. In a Dev, it will have enormous output due to the horn loaded front chamber.
Again, if you want to learn about it, take the advice I just saw given in the Dev Index thread and start looking at the designs, their models, and see how they all compare. Red Five has been exceedingly generous in detailing the compromises of the different designs and he and Chris (AC707... ???) have posted many comparison graphs between different Dev designs.
I recommend starting at the beginning of the first Dev thread:
and reading through that and the index in their entirety.
 
C

cameron paterson

Senior Audioholic
If you go to this page of different subs... 120db at 20hz is almost unheard of! Can the NSW 21" in the Devastator by GSG actually hit 120db steadily at 20hz with 2000 watts @ 6ohms?
 
JasonGSG

JasonGSG

Junior Audioholic
Would this 21" NSW outperform the SI HST 18" if they were both tuned at 17hz in the proper box for each?


Does this subwoofer actually handle 5000 watts RMS?
The NSW will 1000+1% SMUSH the HT18v3!
 
JasonGSG

JasonGSG

Junior Audioholic
Would this 21" NSW outperform the SI HST 18" if they were both tuned at 17hz in the proper box for each?


Does this subwoofer actually handle 5000 watts RMS?
2500
That's not the question, tho, the HT 18v3 is not the HST-18.....
You're correct I read that too quickly.
 
C

cameron paterson

Senior Audioholic
Hey thanks for joining in Jason! I understand the HST-18 is not a pro driver... but how would the NSW 21" in the Devastator enclosure from you guys at GSG and the HST-18 match up with if the 18" was also tuned at 19hz like the Dev?
 
ryanosaur

ryanosaur

Audioholic Warlord
The HST 18 will play lower… far lower. Output? Can’t say for certain.
 
JasonGSG

JasonGSG

Junior Audioholic
Hey thanks for joining in Jason! I understand the HST-18 is not a pro driver... but how would the NSW 21" in the Devastator enclosure from you guys at GSG and the HST-18 match up with if the 18" was also tuned at 19hz like the Dev?
I'm elbow deep into a response to all the above questions. Will be a bit with modelling etc.
I'd recommend reading up in the FAQ section on the GSG webpage for some great explanations about Impedance 4/6/8 etc
 
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cameron paterson

Senior Audioholic
I know the HST 18" will play lower but I only want to compare the GSG with a NSW 21" which is tuned at 19hz and an HST tuned at 19hz. I dont care to compare which gets lower than 19hz. I dont care which performs better under 19hz.
 
ryanosaur

ryanosaur

Audioholic Warlord
I know the HST 18" will play lower but I only want to compare the GSG with a NSW 21" which is tuned at 19hz and an HST tuned at 19hz. I dont care to compare which gets lower than 19hz. I dont care which performs better under 19hz.
I'm interested to see @JasonGSG 's models...
I guess what I meant to convey about the HST is that it will require less power to play 2Hz lower than its Fs, rather than what will be needed to push the NSW 6Hz below it's Fs.
The hardest part is predicting what the in room response may look like.

How this looks to the user is that the NSW may well be tapping the full 2500w or possibly even more to push it in to infrasonics at high SPL.
 
JasonGSG

JasonGSG

Junior Audioholic
That is too many questions. LoL. Took some time to locate all the data & numbers

The Devastator with the Eminence 21 blow's away an HST 18 or an LMS 18 in a Full Marty on the same power.

The Devastator will have the same output, perhaps even a hair more at 19Hz (approx. 120dB) while above 50Hz it soars over 130dB while the HST will be crushing its own output with inductance and struggling to stay at 120dB in the upper bass. The LMS will do a dB or two better. It is not just more SPL, but the efficiency in the upper bass on the Devastator is what makes it particularly special. Its efficiency in the upper bass goes over 30 percent, while the HST and LMS are something less than 0.5% (yes, one half of one percent), which makes the Devastator something like 60x times more efficient at turning electrical power into acoustic power.

The Eminence driver is called a 6 ohm, but has a DC resistance of 3.6, so it could be called a 4 ohm driver. These are just semantics. The Eminence has much more excursion capability than the B&C. At 2kW, the B&C will be out of excursion while the Eminence will have plenty of room to run.

As for power, the Eminence is spec'd at 5000 watts program. That's not sign waves, but it is continuous output. I know we have plenty of bass crazies and I don't recall hearing of one driver burning up yet.

Hope that helps!
 
JasonGSG

JasonGSG

Junior Audioholic
Sometimes we get questions about our recommendation for the LaVoce 8-ohm driver. The story typically goes that the 4-ohm driver will “pull” twice the power from the amp and since “more power is always better”, the 4-ohm driver is clearly better, right?

As a quick primer on amp power, watts are equal to volts squared divided by resistance:

W = V^2 ÷ R

W = watts
V = volts
R = resistance (or impedance)

An example can illustrate how this works. A Behringer NX6000D will be used for the amp and the drivers will be the B&C 21DS115-4 (nominal 4 ohm) and B&C 21DS115-8 (nominal 8-ohm). The actual resistance of each driver is

B&C 21DS115-4: 2.2 ohms
B&C 21DS115-8: 5.1 ohms

Each channel on the amp is capable of 100 volts unloaded (roughly); and each channel on the amp is capable of sustaining 1200 watts of power continuous (roughly). Any more than that and the amp will “power cycle” (i.e. it will shut down so that it doesn’t destroy itself).

And each channel of the NX6000D amp is limited by either:

Max voltage: 100 volts
Max sustained power: 1,200 watts (roughly based on actual measured results)

The GSG 21” Full Marty Roundover cab will be used for the enclosure.

This is the response of the two drivers at precisely 1 watt each in the cab:

B&C 21DS115-4 = black line
B&C 21DS115-8 = red line



The two drivers have essentially the same efficiency, perhaps the 8-ohm has a hair more, but for all practical purposes, the efficiency across the whole bass region is the same.

So let’s turn up the gain and see how many watts will each driver attempt to “pull” from the amp?

Using the equation from above W = V^2 ÷ R

B&C 21DS115-4: W = 100^2 ÷ 2.2 = 10,000 ÷ 2.2 = 4,545 watts.

B&C 21DS115-8: W = 100^2 ÷ 5.1 = 10,000 ÷ 2.2 = 1,961 watts.

Assuming that the amp could survive under those conditions, this is the response that would result:



In the model, the 4 ohm driver is pulling a little more than twice the power than the 8-ohm driver, so it would be expected to have a little more than 3dB advantage across the board.

However, we need to look further into what is going on.

Recall that subwoofers typically have a large change in resistance (impedance) based on frequency). This is how it looks for these subs (the value on the Y axis is ohms). What can be seen here is that where impedance is lowest (around the tuning frequency 17 Hz or so), the amp will be producing the greatest power and where the impedance is highest (around 44 Hz), it will be producing the least power.

[Side note, guys in the car audio world who “burp” their cabs in SPL competitions will typically do so right on the impedance peak frequency in their cabs because it makes the loudest noise while putting the least demands on the amp.
 
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cameron paterson

Senior Audioholic
Awesome! I will be buying a devastator in the near future with an NSW 21".
 

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