Amp Recommend / HO Alt / Check Math

[ekesz13]

Hi all, hoping someone can check my assumptions here and suggest an amp and confirm assumption this application needs a HO alt. Helping a friend, who just bought the following subs:

- Qty 3 of the Sundown Audio E-Series 12" Dual 4 ohm voice coils

These can handle 400W RMS each, so 1200W RMS needed at the speakers. Since the wiring configuration will result in a 2.667 Ohm final load at the Amp, that would mean to find an amp capable of providing 1200W RMS @ 2.667 Ohms, I would need to look for 1600W RMS @ 2 Ohm (using 2.667/2 as the factor). Correct? Any suggestions for a budget (but decent) amp in this range? He is interested in SPL only.

Now, assuming the amp selected (Class D Monoblock) is 70-75% efficient, an alternator @14V would have to put out around 150amps just to run this one amplifier. Correct?

Any help would be greatly appreciated!

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[Da64u 10+ year member]

I've ran 1500 watts on a stock alt with a yellowtop battery no problem. I think upgrading the alt for such a small setup would be a bit much. My friend is currently doing the same also powering an amp for the mids as well. Stock battery and stock alt 80 amp alt.

 

[NASTY08IMPALA 5,000+ posts]

Hi all, hoping someone can check my assumptions here and suggest an amp and confirm assumption this application needs a HO alt. Helping a friend, who just bought the following subs:
- Qty 3 of the Sundown Audio E-Series 12" Dual 4 ohm voice coils

These can handle 400W RMS each, so 1200W RMS needed at the speakers. Since the wiring configuration will result in a 2.667 Ohm final load at the Amp, that would mean to find an amp capable of providing 1200W RMS @ 2.667 Ohms, I would need to look for 1600W RMS @ 2 Ohm (using 2.667/2 as the factor). Correct? Any suggestions for a budget (but decent) amp in this range? He is interested in SPL only.

Now, assuming the amp selected (Class D Monoblock) is 70-75% efficient, an alternator @14V would have to put out around 150amps just to run this one amplifier. Correct?

Any help would be greatly appreciated!

No ho alt is needed for that power ..just a good agm under the hood and big 3 wiring..what size is the stock alt? And has he already bought the subs ..if so id he should trade them for d2 instead of d4 so he can run at 1.34 ohms..cheaper to find good power than at 2.67..if he can get the other d2s id suggest the ppi bk1800.1.should do 1500 or so at 1.34 and cost 200 bucks...a custom box is gona be a big factor for him as well. Dont slap them in a junky prefab box

 

[shauncox26]

I have a old school earthquake sounds phd2 that's 2000@2 with 87% effeincy @2. Small design and puts out loads of power. Could do 200 + sh. Sent it off once only cost $20+- $3.

 

[ekesz13]

You guys are hitting on the concerns I had for him. He got impulsive and bought the subs already, I wish he would have purchased the D2's as well. He also bought a pre-fab box, which I am hoping I can talk him out of (read build him one). The stock alternator is listed at 70 amp.

- Seeing he already has the Subs, any amp recommends?

- So basically you are just using the battery as a reservoir to draw that current out of at peak draw times? Ok. I will suggest he gets the yellowtop and do the big 3.

 

[NASTY08IMPALA 5,000+ posts]

You guys are hitting on the concerns I had for him. He got impulsive and bought the subs already, I wish he would have purchased the D2's as well. He also bought a pre-fab box, which I am hoping I can talk him out of (read build him one). The stock alternator is listed at 70 amp.
- Seeing he already has the Subs, any amp recommends?

- So basically you are just using the battery as a reservoir to draw that current out of at peak draw times? Ok. I will suggest he gets the yellowtop and do the big 3.

Ehh yellowtops arent wat they used to be they got bought out...id suggest a duracell from sams and yea please get him to ditch the box ..thats more important than the amp

 

[NASTY08IMPALA 5,000+ posts]

To get the power u need which is 1200-1600 @2.67 .u are gona need something that does 3k@ 1ohm

 

---------- Post added at 11:06 AM ---------- Previous post was at 11:06 AM ----------

 

Whats his budget on the amp

 

[shauncox26]

Clamped 1465@5.44 ohm rising from 1ohm out the earthquake. Just saying!

 

[ekesz13]

He sent me some links for amps between $150-$200, but they were not making the power he needs. I think $200 is his limit. I will ask him about the Earthquake amp above and see if he is interested. Appreciate all the feedback so far!

 

[NASTY08IMPALA 5,000+ posts]

He sent me some links for amps between $150-$200, but they were not making the power he needs. I think $200 is his limit. I will ask him about the Earthquake amp above and see if he is interested. Appreciate all the feedback so far!

Thats gona be a tough budget

 

[ekesz13]

A bullet he might have to bite then, even if he has to delay and save.

 

[NASTY08IMPALA 5,000+ posts]

A bullet he might have to bite then, even if he has to delay and save.

He could sell 1 and run 2 at 1 ohm .he can meet budget easy then

 

[ekesz13]

That is a suggestion we talked about. Might have to go that route.

 

[NASTY08IMPALA 5,000+ posts]

That is a suggestion we talked about. Might have to go that route.

He could then get a soild new amp with warranty under 200 bucks then withe the money from selling the 3rd he could build a custom box that will probably outperform the 3 12s in that prefab

 

[ekesz13]

For those subs, would you suggest a sealed or ported box? I have only build sealed boxes. Googling now, it looks like there are plenty of offerings at 800W RMS @1 ohm in that price range. Any ones jump out that you would recommend?