New subs don't sound right HELP

[Bryanb]

Hello again got another question bout my system. I finally got my new subs but theirs a problem, ok my old setup was a soundstream stl 1.1200d amp with 2 12in mtx thunder 7500 svc 4 ohm subs. The specs for the amp say its 700 rms @ 2 ohms and 1200 @ 1 ohms. My new setup is the same amp with 2 12in fosgate p3d4 subs I've wired them to 1 ohm and set my gain with my dmm just like before but they don't sound as loud as I thought, they are barely louder than the mtx subs shouldnt they be a lot louder then that givin the increase in power. All connections are correct and the deck, amp, wiring, and box are all the same. What's goin on all help is appreciated thanks.

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[garychoffmann 10+ year member]

Box specs?

 

[jrdnhsnbrg 10+ year member]

Please tell me the box isn't prefab... Also, you might need electrical upgrades depending on your car's electrical to get full power from the amp. What size wiring do you have? That could bottleneck it, too.

Post box specs please! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[bbeljefe]

All other things being equal, going from 700 to 1200 watts likely won't produce any audible gain in sound pressure.

And then as has been mentioned, if your electrical isn't up to par, that increase may only be serving to drop the efficiency of your amp.

It's important to understand that if your amp is 65% efficient at 2Ω, efficiency will drop to ~55% at 1Ω. That means you need 11% more power supplied to the amp just to make it produce the same amount of power.

In simple terms, if a 100 watt amp is 75% efficient, it will take 125 watts of DC power to produce those hundred watts. Drop efficiency to 50% and you need 200 watts of DC power to make the same 100 watts.

This is why I always recommend people over build their electrical... because it takes power to make power.

 

[TaylorFade 10+ year member]

All other things being equal, going from 700 to 1200 watts likely won't produce any audible gain in sound pressure.
And then as has been mentioned, if your electrical isn't up to par, that increase may only be serving to drop the efficiency of your amp.

It's important to understand that if your amp is 65% efficient at 2Ω, efficiency will drop to ~55% at 1Ω. That means you need 11% more power supplied to the amp just to make it produce the same amount of power.

In simple terms, if a 100 watt amp is 75% efficient, it will take 125 watts of DC power to produce those hundred watts. Drop efficiency to 50% and you need 200 watts of DC power to make the same 100 watts.

This is why I always recommend people over build their electrical... because it takes power to make power.

Bingo. So that theoretical +500w increase just turned into maybe 300w or so. But neither increase would be a night and day difference anyway.

 

[Bryanb]

Thanks for all the replies. Yes shamefully it's a prefab box but I don't have the tools to build my own so I did the bat I could here are the specs

Made in the USA with premium 3/4" MDF

1.85 Cu. ft Air Space Per Chamber/Tuning - 38 Hz

Easy Hook Up Terminals

35" W x 15.0" H x 15" D

Automotive Grey Carpeting

My wiring is also rather embarrassing I ordered a cap and amp kit when I bought the amp but got sent the wrong one and couldn't get a response from the seller so I got impatient and installed it anyway. So my wire from the batt is only 6 gauge and my cap is done with 4 gauge power to the amp is 4 but ground is 6 I know I know I've got a 0 gauge kit in the mail so that will be fixed next week thanks for the help please don't be to hard on me I'm on a tight budget as I have four kids and did the best I could with what I had thanks.

 

[Beatin' 10+ year member]

ut neither increase would be a night and day difference anyway

I don't understand this. With my setup, going from 300-600wrms is a HUGE difference.

I'd imagine going from a clean 700wrms to a clean 1200wrms would result in a dramatic gain in SPL, assuming minimal power compression.

 

[jrdnhsnbrg 10+ year member]

[quote name='Bryanb']Thanks for all the replies. Yes shamefully it's a prefab box but I don't have the tools to build my own so I did the bat I could here are the specs
Made in the USA with premium 3/4" MDF
1.85 Cu. ft Air Space Per Chamber/Tuning - 38 Hz
Easy Hook Up Terminals
35" W x 15.0" H x 15" D
Automotive Grey Carpeting
My wiring is also rather embarrassing I ordered a cap and amp kit when I bought the amp but got sent the wrong one and couldn't get a response from the seller so I got impatient and installed it anyway. So my wire from the batt is only 6 gauge and my cap is done with 4 gauge power to the amp is 4 but ground is 6 I know I know I've got a 0 gauge kit in the mail so that will be fixed next week thanks for the help please don't be to hard on me I'm on a tight budget as I have four kids and did the best I could with what I had thanks.[/QUOTE]

Do you still plan on running the cap? Because you shouldn't. They're a great waste of money. If I were you I'd sell the cap on craigslist or return it and save up to have a good ported box made by a pro, such as @Buck ;. Use all 0 gauge and do a big 3 kit. Trust me man I understand a tight budget, I'm a college student and my anniversary with my girlfriend is coming up soon and I spoil her so yeah... Just gotta be patient and start saving. I have big plans for my personal system that are gonna take months to save for.

 

[Bryanb]

Yeah I'm gonna keep it it helped with my headlights dimming and my amp will only accept 4 gauge so I'm gonna run 0 to the cap and 4 to the amp. I'm planning the big 3 next and the an aux batt, and with taxes a ho alt so I'm workin on it just wanna be sure the subs aren't bad I'm tryin to be patient but it's hard. How big will the box need to be I have a cavalier so my trunk is pretty small thanks.

 

[jrdnhsnbrg 10+ year member]

Yeah I'm gonna keep it it helped with my headlights dimming and my amp will only accept 4 gauge so I'm gonna run 0 to the cap and 4 to the amp. I'm planning the big 3 next and the an aux batt, and with taxes a ho alt so I'm workin on it just wanna be sure the subs aren't bad I'm tryin to be patient but it's hard. How big will the box need to be I have a cavalier so my trunk is pretty small thanks.

Buck will make it to the exact size you specify, make sure to measure the opening of the trunk and not the trunk itself.

 

[Bryanb]

Ok but I know the box I have now is as big as I can fit through the opening. I've seen ppl online put them in through the pass through with the seat folded down bout how much do you think it'll cost. Does the manufacturer specs matter cause the specs from rf say 1.79 for ported and mine is 1.85 so I should be ok right what are the benefits to a custom box if mine is the right size thanks.

 

[Buck 5,000+ posts]

Box is a little small for my taste, tuned to high, and probably not enough port area.

 

[Bryanb]

So I should ignore the specs that rf gave me with the subs?

 

[Buck 5,000+ posts]

So I should ignore the specs that rf gave me with the subs?

Yes. They ****. Airspace is usually right but tuning/port area aren't really reliable at all.

 

[Bryanb]

Hmm. Confusing I just want to do this right so what do I do now