What size amp do I need to power these subs?

**ThePistonDoctor** · 06-07-2008, 02:36 PM

Originally Posted by techy101

The fuses that are under the terminals are how it's a dual voice coil sub. When there are two fuses in it should be running the two 4 ohm VC's in parallel, making it 2 ohms. Even without the fuses, if internally the two VC's were in parallel or series it would still be a dual voice coil sub (assuming of course it had two).

With a mono amp he could set these up in Series and run at 4 ohms. No need for a 1 ohm stable amp.

So how do you choose whether it's in series or parallel? On every DVC sub I have ever seen (and I have installed hundreds...lol) there are two physically separate voice coils, each with their own set of terminals. When you want to wire it in series, you go from one coil's negative to the other coil's positive, then with the pos/neg left over you go to the amp. In parallel, the positives/negatives from each voice coil are soldered or twisted together, or you go from VC1(-) > VC2(-) > amp(-), VC1(+) > VC2(+) > amp(+).

Here you've only got one set of terminals...so how is the series/parallel determination made?

**ThePistonDoctor** · 06-07-2008, 02:40 PM

Originally Posted by techy101

They fail to mention that that jet engine measurement is at about 40'. At 1 foot it would be in the 150dB range. Also, the difference between 108 and 120 is MUCH larger than the difference between 85 and 97 since it's a logarithmic scale. Also, without distance being specified the numbers are worthless, since every time you double the distance from a point source you loose 6dB. It's a lot like trying to compare Horse Power and Torque between cars, but ignoring the drivetrain and weight of the vehicle. A lotus has a "small" engine, but is fast as snot cuz it's so light, vs. a mustang that has a much larger engine, but weighs a ton compared.

As well, because of the frequencies we're talking about higher SPL is required than in the mid range, since we don't hear in a linear fashion. This is represented by the equal loudness curve. At ~3,000hz if something is perceived as being 100dB SPL, then to duplicate that perceived SPL for 50Hz you would need an increase of ~20dB for them to sound the same "loudness"

I understand all that. All I'm saying is that you don't need 125-150db @ 30-100hz to have a little extra bump in your system. your calculated 100-110db should be fine for the average person. The last SPL system I had in my mustang hit 151.2dB @ 37Hz and it was enough to bounce a penny on the roof about 6" in the air. lol

**techy101** · 06-07-2008, 02:40 PM

It's made at the factory. The price you pay for a cheaper sub. In this case you can tell that it's clearly in parallel in one fuse configuration and in series with the other fuse configuration. They just use the fuses instead of multiple terminals.

**techy101** · 06-07-2008, 02:44 PM

Originally Posted by ThePistonDoctor

I understand all that. All I'm saying is that you don't need 125-150db @ 30-100hz to have a little extra bump in your system. your calculated 100-110db should be fine for the average person. The last SPL system I had in my mustang hit 151.2dB @ 37Hz and it was enough to bounce a penny on the roof about 6" in the air. lol

My point was more that since he wasn't getting enough from his current setup, then he shouldn't be looking at the amp for the fault. Also, those numbers are in a perfect setup, which I doubt this is (no offense). I doubt that the OP has gone though and properly setup his/her gain structure and x-overs. And that he would get much much much more bang for his buck by looking into better subs versus a new amp since the gains by increasing power are minimal at best (3dB for every time you double the power).

**ThePistonDoctor** · 06-07-2008, 02:58 PM

Originally Posted by techy101

It's made at the factory. The price you pay for a cheaper sub. In this case you can tell that it's clearly in parallel in one fuse configuration and in series with the other fuse configuration. They just use the fuses instead of multiple terminals.

Ahh yeah that makes sense. If that's the case he's running 2 ohms per sub right now, and I'm assuming the amp channels are internally bridged since it's a single channel amp?

If that's the case, if they are internally bridged in PARALLEL he is running a 1 ohm load which is NOT GOOD. If they're internally bridged in series he is at a 4 ohm load and 150W per sub. Either way, the most the OP is going to get out of that amp w/ these subs is 150W RMS per sub. That is indeed a bit underpowered...

If the amp is internally bridged in parallel that could explain why it sounds weak (the amp is not stable at 1 ohm) so OP, you could try the other fuse configuration which would give you a 4 ohm final load and see if that makes a difference.

Edit: Techy in a way I agree with you. The problem is not really the subs OR the amp...the problem is that the subs and amp are not ideal for each other. The voice coil configuration on the subs is not optimal to get the most power out of the amp, so if he wants to stick with those subs he should just get an amp that is stable at 1 ohm. If he wants to keep that amp, he should get subs that he can wire to a 2 ohm final load and that can handle at least 300W RMS. Personally I'd ditch the amp because I hate Rockford Fosgate.

**techy101** · 06-07-2008, 02:59 PM

Or wire the subs in series. That would also work just fine.

**Kurack** · 06-07-2008, 03:07 PM

Ok so here is what i did as a test...

First off, the fuse configuration only allows me to configure for 2ohm (default - both fuses in) or 8ohm (1 fuse in the middle)...I cant do 4ohm config <?>

I hooked one of my subs up that i replaced ( punch HX2) and it thumps nicely...but the G5 isnt.

So you think if i wire the subs together it can help? so from the + on the amp to the + on one sub, then from that + to the other subs + , same for negative?

I know i am new, i will learn and read everything...i'm just looking to find out why the G5 isnt thumping at the moment...again thanks for whatever info you give me

**Kurack** · 06-07-2008, 03:08 PM

So....if i want to keep these sub, which I do. what amp would you guys recommend I get for them?

**techy101** · 06-07-2008, 03:09 PM

leave them in 2 ohm config. Then wire from pos on the amp to pos on one sub, then a wire from neg of that first sub to pos on the second sub. Then from neg on the second sub to neg on the amp

Ignore the numbers. This is just a pic i found on google image search.

**Kurack** · 06-07-2008, 03:30 PM

Ok techy101.....i think I just ****ed my neighbors off about 4 blocks away wiring it up like that LMAO....

Awesome.....I can leave it like this which is thumping amazing now, or I can upgrade the amp which would be better overall....that being said, what amp do you recommend for these speakers.