is this right?

i hooked up my subs and amp differently today, now that i have a bit of knowledge on impedence.  i have a 4 ohm stable amp and 2 - 4 ohm SVC 10" subs.  i hooked them up to get 8 ohm's ( + and - of opposite subs put together and the + on one sub and the - of the other sub go to the amp)  then to get the 4 ohm's required, i hooked up the subs to the MONO speaker connections.  This is they way i understood the way to wire subs someone please let me know if i did it wrong.  Aside from that i installed an active crossover set at 80Hz and 18db (it also has a phase option 0 or 180...not sure what that is?) i also installed an RCA cable from the crossover to the amp which  was modified by 'cutting off the ends of the RCA cables, combining the signal grounds (the outer shield), and then using a 1 kOhm (1/4 watt, 5% tolerance) resistor to each of the center conductors.  I Soldered and insulated the resistors so that I didn't short them prematurely, and then connected the two resistors together. Then i connected the summed signal ground to the shield of the new RCA plug, and the summed center conductor to the center pin of the RCA plug.'  The info for modifying the RCA cable was off the following site. 

 https://www.mobileaudio.com/rac-faq

does the setup sound like its done properly?  or is there something i should change.  I'm really excited about the way it sounds now ...I cant wait to finish the rest of the system.  I have to thank the members on the forum that are helping out and have posted great knowledge on the forum..its AWESOME

Phoenix Gold's FAQ wrote:

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If an amp is rated to handle 4 ohm bridged, then it can handle 2 ohm stereo. It's the same total power. The minimum stereo load is always 1/2 of the bridged capabilities. Each amp channel must deal with 1/2 of the total load (1/2 + 1/2 = 1). So whether it's running 2 ohm stereo or 4 ohm bridged, the amp responds to the load the same. That's why you see power specs like 200 watts x 1 at 4 ohms bridged OR 100 watts x 2 at 2 ohm stereo. It's still 200 watts.

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I was just reading up the specs again for the amp and i got a little confused and am now wondering the better way of wiring the subs now.

RMS power measured at 12.5V DC:

125W x 1 into a 4 ohm load with less than 1% Thd+N

250W x1 into a 2 ohm load with less than 1% Thd+N

Dynamic Power measured at 14.4V DC:

200W x 1 into a 4 ohm load

350W x 1 into a 2 ohm load

does this mean that the amp is able to operate efficiently at both 2 and 4 ohms?  am I only putting out 125W then?

this is my setup now

Is this What i should be doing then to get the 2 ohm load and 250W?

MTX  - THUNDER 4250D

From what I have found you have a mono sub amp that is designed and engineered to operate at 2 ohms. This is the correct wiring method for you.

The RCA cables were modded awhile ago for a cheap pioneer amp that didnt have the capability of being bridged, so i made this cable so i could get a mono signal to the subs, at least that was and is my understanding of how it works untill i get told otherwise...but it was the perfect length from the crossover to the amp so i used it.  It seems to make a cleaner sound as apposed to straight RCA but i'm not sure if the resistors cut back just the right amount of power (which i should have adjusted with gain) or if the quality of the one RCA cable is that much better (doubt it) or if it just creates a cleaner mono signal having been converted before entering the amp...any thoughts or is it probly just in my head?

I just finished wiring up the subs as per the diagram above (2 ohms) and it sounds pretty amazing, packs quite the punch.  I have 2 of the old skool JBL subs (black with the white raised letters) and i was wondering if i would get a louder and better quality bass if i used a newer, better sub... I'm kinda looking towards Premier subs (i will need 4, with 2 being inverted).  at 110.00 is there a better brand or would ther pretty much stay the same across that price range? this sub is 350W RMS and 800W peak...should i be looking for something with a closer rating to what the amp puts out (would this be underpowering the sub?)

placid warrior wrote:

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should i be looking for something with a closer rating to what the amp puts out (would this be underpowering the sub?)

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Here are some good answers in this forum search for "underpower".

Sorry, i should have known to do a search, but thank u.  I'll try to find something else than, probly with a 100W RMS and 400W peak like i am running now(should be a bit cheaper too than and allow me to get a better quality sub).

I didnt see anything stating if underpowering a sub with no clipping sounds the same as a sub with approx the same RMS as the amp set at the same gain.  But i did learn something very important....not to let the smoke out of my subs or they wont work anymore I think i'll try to make something that can put the smoke back in the electronics and then sell it on ebay...

I know that amplifier ratings vary on the quality of the amp...but is that the same with subs?  will a cheapo pioneer actually have the proper RMS rating on it and still handle the power the same as say a rockford, even though the sound quality it a billion times better with the rockford? ( i have a feeling that the answer is no though and the cheaper sub will most likely fry quicker)  can anyone suggest an inbetweener sub that sounds quite good for the price and can do me over for quite awhile without feeling the need to upgrade? (MTX is supposed to be good)

placid warrior wrote:

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( i have a feeling that the answer is no though and the cheaper sub will most likely fry quicker)

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Unless the speaker has some dramatic flaw, you can run a cheap speaker as long as you can run a high-end speaker...if you always keep the power well below the RMS of the sub.  It's when you push the limits of the operating range that bad things can happen, and that's where the better speakers will often tolerate abuses a little better because of their build quality.  Here's a rating you see often with replacement-type coaxial speakers:  "power handling 2 - 60 watts RMS" ;  this example is to show that a speaker of any size will operate at a very wide power range UP TO the RMS.

placid warrior wrote:

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I didnt see anything stating if underpowering a sub with no clipping sounds the same as a sub with approx the same RMS as the amp set at the same gain.

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Let's just say that both amps in question have gains correctly set...if you can subtract out the difference in actual 'sound' from one subwoofer to another, then yes, one will be equal to the other in that scenario. 

placid warrior wrote:

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I'm kinda looking towards Premier subs (i will need 4, with 2 being inverted).  at 110.00 is there a better brand or would ther pretty much stay the same across that price range? this sub is 350W RMS and 800W peak...should i be looking for something with a closer rating to what the amp puts out (would this be underpowering the sub?)

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You started out this thread with two subs and the MTX 4250D amp, but now you are saying you are looking for 4 subs.  Are you still referring to the same one amp?

thanks for the replies stevdart.  which of the 3 brands or the most show looking alpine7995?

The reason i say 4 subs is cause i will be getting another amp (exact same) and will be running the 2 other subs off of it.  The box i have now (holds 2 subs with a divider...and i did seal the divider totally now) is a sealed box, but i was thinking of making the other 2 boxes ported for more of a boomy bass.  the 2 boxes are smaller because of the location and i am positive that the airspace will be way to small with the sub in and not much better with it inverted (i suppose using a pile of sound damping material would work to make the box seem bigger to the sub?) which is also why i was thinking of porting. The boxes for these subs are in progress...all i have to do is caulk the joints and place the rings, then if i port or not i will fleece over it, at the moment i cant afford to glass these boxes so i have a bit of time to figgure things out before i feece.

I know there is a problem when running 2 different size subs...is there going to be the same problem if i have the 2 different enclosure types?

thanks again for your replies guys.