Inverted Subs and amp Q.

[vega]

Hello !!!

1 - I just got this 12 subs (1300W Peak Power *380 W RMS*
4-Ohm Voice Coil )


http://i22.ebayimg.com/08/i/000/f4/ag/5a2e_1.JPG

To save space and for aesthetics i want to mount them inverted.

Manufacture instructions state that this subs work best with sealed inclousure and also gives the dimensions for it, however, ive been reading and searching for this and i found this, that kinda makes sence.

""When youre building the box, make sure to compensate for the fact that the sub is no longer taking up any space in the box so the box will need to be made smaller"".

Do i calculate the space of the back part of the sub and deducted from the box ?? or should i build it with the same dimenstions manufacture suggest ??


2 - I need to buy an Amp for this subs, i was thinking of getting this 2 channel : (i know i would only get 50% of the subs with this amp)

http://cgi.ebay.com/SONY-XPLOD-XM-GTR2022-1200-WATT-2-CH-CAR-AUDIO-AMP-NEW_W0QQitemZ360063569995QQihZ023QQcategoryZ39732Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem


but again reading and searching i found this statement.

""one of the major advantages of a mono amplifier is that you can hook it up to 1, 2, 3, or even 4 subs, and get equal power to each sub. Mono amplifiers are designed specifically for bass, so you can be sure you will get more bass power out of it than an ordinary 2 channel amp. ""


So im now thinking of getting this one.

http://cgi.ebay.com/SONY-XM-D9001GTR-Class-D-Monoblock-Mono-Amplifier-Amp_W0QQitemZ290240593474QQihZ019QQcategoryZ64570Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem

What do you recomend ??


I know there are better/cheaper brands but ive always like how sony looks/sounds plus its right on my budget.

Apreciate any help

Any suggestions / comments are welcome.

thanks

Vega

[SeRiousZX2]

You need to find out what the displacement of the subs are. They are usually posted with the subs specs or on the manufactures website. You then subtract that from the boxes internal volume.

The Sony XM-GTR9001 is a little too much amp. Not that it would hurt, but you will need to tune it perfectly to not blow the subs. Running a little bit more powerful amp is fine and actually better. This will keep the amp running cooler and last longer because its not maxed out.

[vega]

The Sony XM-GTR9001 is a little too much amp. Not that it would hurt, but you will need to tune it perfectly to not blow the subs.

Thanks for the inpunt, any suggestions on a Sony 1 channel amp ??

thanks

vega

[dragon2200]

Hate to say this but when you invert subs with a sealed enclosure more often than not you need to make the box the same size and sometimes bigger for it to sound right. Older Audiobahns used to require more space in the enclosure for optimal sound quality.

[dragon2200]

Personally Imo Sony isn't very good quality, you want good crisp clear sound sub wise use Memphis, Re Audio, JL audio, JBL, Mtx and some others just watch for deals, as for Amps as far as I know Sony doesn't do a monoblock or at least they didn't used too, but Memphis and Planet audio are my preferences amp wise, Jbl is good Mtx is moving way up in the world of car audio.

But no matter what Sony is low end Wal-Mart crap, sorry.

[vega]

I know there are better/cheaper brands but ive always like how sony looks/sounds plus its right on my budget.

But thanks for your suggestions.

vega

[vega]

any more info ??

thanks

vega

[soundman1024]

I think your amp choice should work out so long as you're listening for distortion. In the pro audio world we try to have an amp that puts out double what the subs can handle. This allows us to get clean, undistorted waves to the speakers. If you can prevent distortion from getting to the speakers you can usually push them further than what they're rated for. If you know what distortion sounds like and are willing to turn your volume down if you hear it you should have a fairly good match there. If you don't hear distortion too well look for something that puts out around 700w RMS or 1400w peak in mono at 2Ω.

Be sure to wire your subs in parallel. Put all the +s together and all the -s together. By wiring in parallel your amp will get a 2Ω load from the two 4Ω voice coils. This will give you 900w RMS out of it. If you were to wire in series it would be an 8Ω load, giving you 275w RMS.


Lastly, if you're trying to get the most SPL out of these that you can, mounting these speakers with the magnet sticking out isn't going to help. About 60% of the sound a speaker makes comes from the front, and 40% from the rear. If you're pushing 60% of your sound into a box and 40% in your car it isn't as efficient.

[CJW]

1:
If you invert the subs you are placing the subs 180 degrees out of phase. IF you invert the subs you do not need to calculate for the airspace being used by the subs since they are not using the airspace. To cure the phase issue you can either adjust your amp(if it has a phase control) or wire them backwards(negative to positive and positive to negative)

2:
I suggest finding an amp that puts out 760rms. I personally would be looking more around 1000rms for buffer room.
I can't tell what ohm those speakers are so I can't help tell you want kind, brand, or whatever of amp to get.

Most 2 channel amps are now stable to 2ohm per channel. Which is perfect for 2 subs that are single 2ohm or dual 4ohm or dual 1ohm(not likely).

However, most mono blocks are stable to 1ohm. 2 dual 4s can be wired to 1. The mono will have a smaller footprint. And pending the type of amplifier may run cooler for longer periods of time.

Most 2 channels are still running on a/b technology which IMO is superior to class d/t due to the sound quality. BUT they do run hot, they are large, and for a good one they are expensive.

You have a buttload of options. BTW I didnt read any of the replies so this may all be covered already.

[SeRiousZX2]

But no matter what Sony is low end Wal-Mart crap, sorry.

Worst statement of the year.......

Anyways, Sony only sells thier low end to Wal Mart. Ex: Have you ever seen thier XS-GTX1620S at Wally World???? I think not young grasshopper.

An yes, Sony DOES produce a Mono Amp. They have for years...
But then again, you have only been looking at the Wal Mart Sony.

[dragon2200]

Worst statement of the year.......

Anyways, Sony only sells thier low end to Wal Mart. Ex: Have you ever seen thier XS-GTX1620S at Wally World???? I think not young grasshopper.

An yes, Sony DOES produce a Mono Amp. They have for years...
But then again, you have only been looking at the Wal Mart Sony.

Well if they have for years cool I haven't used a Sony amp for 8 years as the sound quality is no where near any of the brand names I listed, the way I look at it is any brand that has to sell out it's reputation to Wal-mart is desperate, I stopped buying Pioneer for the same reason.

Get me specs of Sony's true rms output, not what's branded on the amp but it's true power which I bet is around 60% of what's stated if not less.

As for the grasshopper statement I used to install car audio professionally, Thank you.

[CJW]

Well if they have for years cool I haven't used a Sony amp for 8 years as the sound quality is no where near any of the brand names I listed, the way I look at it is any brand that has to sell out it's reputation to Wal-mart is desperate, I stopped buying Pioneer for the same reason.

Get me specs of Sony's true rms output, not what's branded on the amp but it's true power which I bet is around 60% of what's stated if not less.

As for the grasshopper statement I used to install car audio professionally, Thank you.

While I agree even sony's high end stuff I wouldn't run...being a "professional installer" means nothing. And being you are "in" the industry you should know that. A piece of paper and/or a job doesn't make a person good or knowledgeable. I have personally fixed 7headunit installs by circuit city in the past 4 years. AKA every circuit city headunit install my friends have had. Those pros sure know how to install eh?

RMS ratings on amps are even skewed. Anyone who buys a 1000rms amp and runs it on a stock electrical system and claims 1000rms is a fool.

[SeRiousZX2]

Well if they have for years cool I haven't used a Sony amp for 8 years as the sound quality is no where near any of the brand names I listed, the way I look at it is any brand that has to sell out it's reputation to Wal-mart is desperate, I stopped buying Pioneer for the same reason.

Oh please...

You can find JBL and MTX at every Flea Market and mexican Bazzaro across the nation. That doesn't mean they are a crap brand or thier sound quality is any worse than others.

[SeRiousZX2]

RMS ratings on amps are even skewed. Anyone who buys a 1000rms amp and runs it on a stock electrical system and claims 1000rms is a fool.

US Amps and Cadence FTW!!!!

[03zx2]

What this all comes to is everyones personal choice.

[JonsZX2SR]

Class D amps are fine for purely subwoofer applications. Considering that the low pass freq. to the sub is going to be below 400 Hz and the switching freq of any good Class D amp is going to be 20-100 times this (5 KHz-40 KHz) or greater, the filtered output to the speakers is going to be pure analog anyway.

Greater efficiency, less heat generation, faster transient response, less tendency to generate a DC voltage at the speakers and less required negative feedback for stability are all advantages for Class D (switching) amps. As you approach 1 KW rms the cost differential between analog (Class AB) and switching amps (Class D) decreases.

For full range audio I agree with you. To get clean output extending to 20 KHz you need a switching freq significantly above 40 KHz using filters capable of removing high freq. energy without wasting power. Even though you may not hear 44.1 or 48 kHz energy, this will heat your tweeters, saturate the magnetic fields and also cause intermodulation distortion between high freq. signals.

I'd guess for very clean full range Class D audio, you want the switcher to be running at least at 75 KHz with 100 KHz or greater being preferred.