RD vs Sundown?

[t1990le 10+ year member]

Technically the two RD Alpha 12's don't out-displace the single Nightshade 15. See this quick comparison below:
Two RD Audio Alpha 12 D1’s (assuming he has two D1's since his final impedance is 1 Ohm):

Per Alpha 12;

Sd: 490 cm^2 (giving it credit because RD doesn’t list Sd)

BL^2/Re: 263 (assuming that RD's Re is correct with 1.3 Ohm with the coils wired in series)

Xmax: 16mm

Displacement for one Alpha 12: 784 cm^3 for one, so 1568 cm^3 for two.

One Sundown Audio Nightshade 15 D1:

Sd: 810 cm^2

BL^2/Re: 173

Xmax: 23 mm

Displacement for one NS15: 1863 cm^3

thanks, the alphas r actually dual4 idk if that makes a difference but you are saying the NS should deff be louder since it will have more cone area and more power right?

 

[Papermaker85 5,000+ posts]

how are the nightshades xmax figures calculated? i know that alpha is simply coil height-TP height/2... ethier way the alphas aren't bad woofers and they do great with 1200-1500RMS per.. i know they can handle more for music as well.. while the night shade is a great woofer the 2 12s with 3K are going to be more efficient...

 

[Papermaker85 5,000+ posts]

interesting that the parameters have some faults... seems like A incorrect RE B incorrect BL or C incorrect SD... im almost positive its A.. this is for the nightshade

 

[Electrodynamic 10+ year member]

interesting that the parameters have some faults... seems like A incorrect RE B incorrect BL or C incorrect SD... im almost positive its A.. this is for the nightshade

The latter specifications were taken directly from the Sundown Audio web site here, Sundown Audio - Nightshade 15". The BL is specified as 22.8, Re is 2.92 for the dual D2, which leads BL^2/Re to be 178. Sd is taken directly from Jacob at Sundown. How are those figures wrong? The parameters are with the coils in series, which is the industry standard. We are talking about a Sundown Nightshade v1 aren't we? I assume so, since the v2's aren't out yet.

 

[Electrodynamic 10+ year member]

thanks, the alphas r actually dual4 idk if that makes a difference but you are saying the NS should deff be louder since it will have more cone area and more power right?

I can't find T/S specifications on the D4 version of the Alpha on RD's web site. Does anyone have a link to, or any information on, the T/S's on those drivers?

 

[Electrodynamic 10+ year member]

how are the nightshades xmax figures calculated?

I was being nice with the estimate of 23mm even though by FEA modeling the NS v1 is capable of 25mm one-way linear. When you re-do the math with the actual Xmax figure on the NS v1 (be sure to convert mm to cm for your math), it will solidify the out-displacement even further.

 

[audioinformer 10+ year member]

The coil in the Nightshade v1 that I re-built had a 55mm winding width coil and a 25mm top plate. That would have 15mm X-max and I understand that it can move up to 27.5mm with 12.5mm of the coil out of the gap but, the X-max is 15mm.

The RD Alpha v.2 that I re-built had a 50mm winding width coil and a 20mm top plate. That would have an X-max of 15mm and I understand that it could move up to 25mm with 10mm of coil out of the gap but, the X-max is 15mm.

How to calculate X-max: Coil Winding Width minus Top Plate divide by 2.

Nightshade v.1 (55 - 25 = 30 / 2 = 15) 15mm X-max

RD Alpha v.2 (50 - 20 = 30 / 2 = 15) 15mm X-max

X-max Definition: X-max is the amount by which the voice coil can move in one direction without it leaving the magnetic gap.

 

[skmfkr 5,000+ posts]

that and i think the nightshade can handle 3000watts better than 2 alphas

lol why do you think one sub and handle more power than two?

 

[t1990le 10+ year member]

lol why do you think one sub and handle more power than two?

idk i guess bc if i blow it Jacob can get me a recone in less than 6 weeks

 

[Electrodynamic 10+ year member]

X-max Definition: X-max is the amount by which the voice coil can move in one direction without it leaving the magnetic gap.

Xmax is the point where 70% BL remains from the rest position (one-way). Klippel and DUMAX both define it that way.

 

[audioinformer 10+ year member]

Technically the two RD Alpha 12's don't out-displace the single Nightshade 15. See this quick comparison below:
Two RD Audio Alpha 12 D1’s (assuming he has two D1's since his final impedance is 1 Ohm):

Per Alpha 12;

Sd: 490 cm^2 (giving it credit because RD doesn’t list Sd)

BL^2/Re: 263 (assuming that RD's Re is correct with 1.3 Ohm with the coils wired in series)

Xmax: 16mm

Displacement for one Alpha 12: 784 cm^3 for one, so 1568 cm^3 for two.

One Sundown Audio Nightshade 15 D1:

Sd: 810 cm^2

BL^2/Re: 173

Xmax: 23 mm

Displacement for one NS15: 1863 cm^3

So, if you are going by the amount of one way linear movement while maintaining 70% of the BL obtained with 1 watt of power as X-max, I guess according to you the RD Alpha is unable to move out of the gap and maintain a minimum of 70% Bl loss? If you add X-max to the Alpha's in your equation, then it might be possible for two 12" Alphas to have as much or maybe even more displacement as one 15" Nightshade? I really don't care for either driver, I just didn't see how your math was accurate in your displacement values. My opinion is go with the company that can and will help you in the future with their product or make sure you can find another company that can fix it before you buy it.

 

[skmfkr 5,000+ posts]

idk i guess bc if i blow it Jacob can get me a recone in less than 6 weeks

so cuz jake can get u a recone in less than 6 weeks means 1 sub can take more power than 2?

 

[basebalz13 10+ year member]

Technically the two RD Alpha 12's don't out-displace the single Nightshade 15. See this quick comparison below:
Two RD Audio Alpha 12 D1’s (assuming he has two D1's since his final impedance is 1 Ohm):

Per Alpha 12;

Sd: 490 cm^2 (giving it credit because RD doesn’t list Sd)

BL^2/Re: 263 (assuming that RD's Re is correct with 1.3 Ohm with the coils wired in series)

Xmax: 16mm

Displacement for one Alpha 12: 784 cm^3 for one, so 1568 cm^3 for two.

One Sundown Audio Nightshade 15 D1:

Sd: 810 cm^2

BL^2/Re: 173

Xmax: 23 mm

Displacement for one NS15: 1863 cm^3

Nick im confused on your statement.

Cone area of 2 12's is 226 sq inches. Cone are for a single 15 is 176 sq inches. Difference of 50.

Xmax is 16mm on the Alpha v2 however there is two 12's. Nightshade you said had 23mm and one 15".

"stock" Alpha will handle 1500rms

"stock "nightshade will handle 1500rms

Just my .02 cents

 

[sundownz Pro Seller]

If you will be running the NS 15 @ 0.5 vs. the Alpha 12s at 1 ohm the NS 15 will likely be louder simply from more power.

Assuming they have equal x-max... just for the sake of argument... you have ~77% of *maximum* displacement of the two Alpha 12s using a single 15" Nightshade (I'm just using the simple divide cone diameter in half for SD calculation to eliminate calculation variances).

But... neither will see full x-max at the loudest frequencies (around box tuning **) anyway so the extra power from dropping to 0.5 will likely push the NS ahead in output by a bit. Hard to find accurate T/S on the Alpha as there are so many versions but quite likely the NS v.1 has a higher motor force factor as well which will help you out in output ported.

Is the difference worth making the trade ? Not so sure... and we are just talking in theory anyway... hard to say what will happen in your car.

** -- We have a low tuned box reaching nearly 150 dB @ 35 Hz with one NS 15 with 2500 clamped watts and it is *still* not at full throw... box is tuned right around the 35 Hz range similar to your plans.

 

[t1990le 10+ year member]

so cuz jake can get u a recone in less than 6 weeks means 1 sub can take more power than 2?

No it doesnt mean that it can take more power it just simply means if i aquire that kind of power in the future and i accidentaly blow the sub/s jacob, from what ive read and expirenced, would be alot better to deal with than steve.

If you will be running the NS 15 @ 0.5 vs. the Alpha 12s at 1 ohm the NS 15 will likely be louder simply from more power.
Assuming they have equal x-max... just for the sake of argument... you have ~77% of *maximum* displacement of the two Alpha 12s using a single 15" Nightshade (I'm just using the simple divide cone diameter in half for SD calculation to eliminate calculation variances).

But... neither will see full x-max at the loudest frequencies (around box tuning **) anyway so the extra power from dropping to 0.5 will likely push the NS ahead in output by a bit. Hard to find accurate T/S on the Alpha as there are so many versions but quite likely the NS v.1 has a higher motor force factor as well which will help you out in output ported.

Is the difference worth making the trade ? Not so sure... and we are just talking in theory anyway... hard to say what will happen in your car.

** -- We have a low tuned box reaching nearly 150 dB @ 35 Hz with one NS 15 with 2500 clamped watts and it is *still* not at full throw... box is tuned right around the 35 Hz range similar to your plans.

Ok, I have a few designs on my comp that i made for a box or two. The ns would be in my reg cab f150 in about 4.5 cu ft and 76sq in of port tuned to 36hz. Sub forward behind driver seat and port up behind passenger.

Whats the mounting depth of the ns btw?