PDX M12 for 2 MM1240s?

VR028

as the title states im thinking of getting a pdx m12 to power 2 mm1240's.
will it be too much power or should i just get the mrx m100 to be a little safer?
if i do so would i lose sq between the pdx and mrx?

pentoncm

I wouldn't worry about a SQ quality difference between MRX and PDX. You won't be able to hear any difference because it is just bass. Also you should be crossing at 60Hz or below so there is no way you could tell a difference.

The alpine amps are underrated. I have the MRX50 and the birth certificate said that mine produces 592W RMS. So if you got an MRX1000 it would likely produce 1100W to 1200WRMS (alpine says their amps are 10-20% underrated).

Go to cartoys.com and check the price, they are sometimes the cheapest by a good amount.

I wouldn't go with PDX simply because you don't need the extra power.

Don't worry about overpowering because its not like you will be using 1200W continuously. That would only be if you turn the amp all the way up to max. If you back it down by 3db you drop the power output by half to 600W.

VR028

ok so even if the sq is the same id still be inclined to go with the pdx simply for the smaller footprint and symmetrical look of 2 matching amps as i have a pdx f4. i know it seems a little pedantic but i really want my new install to look good as well as sound good.

so i guess your saying the polks will be ok on about 500-600w rms each? i dont really ever crank the volume unless im showing off to a friend and even then thats only for a few seconds. should i just go for something like an alpine type 12 sub which can safely handle the power or should i stick with the polks and be careful?

pentoncm

As long as you are using a sealed box you should be fine.

I've read multiple places that type R's sound better in ported boxes, they are not as SQ oriented.

If you don't want to be able to max out the system just keep the gain down so that you never reach max power. Do you know how to set the gains using an O scope? That would tell you where your amp clips/reaches max power and from there you could just take it down a notch or two to be safe.

VR028

well no its a ported box. a few months ago when i emailed polk they sent me a ported box design that i changed around slightly to fit my car. its a 3.5 cu ft box with a slot port tuned to 33hz.

im beginning to think type r is the go

pentoncm

MM subs aren't specifically made to be ported so a Type R would probably be better in that box. Nice that its tuned to 33Hz that should give you nice efficiency and a decently flat response. Make sure to use the subsonic filter however.

VR028

pentoncm wrote: »

MM subs aren't specifically made to be ported so a Type R would probably be better in that box. Nice that its tuned to 33Hz that should give you nice efficiency and a decently flat response. Make sure to use the subsonic filter however.

thats what i always though however this box design was recommended by polk when i emailed them. their exact words were "Ported definitely…. Much higher output levels"

i modelled it on bass box 6 and changed the shape slightly and tuned it lower to my liking. heres the box they sent me

pentoncm

i'm surprised that they told you ported. However those specs are specific for the mm subs. Double check if everything will be ok for the Type R subs. The volume of the box might be different for the type R.

Sealed almost always sounds better. Its easier to integrate with the mids upfront and has a more even frequency response. However as you lower the tuning frequency the ported box approaches the SQ of a sealed box.

VR028

yep the type r's show almost an almost identical curve just slightly louder due to the higher power, they also play slightly lower too. this box is within spec for most 12" woofers. i think ill go with the r's for peace of mind. after a second listen of both subs the sq isnt far off the polks imo so ill get the type r's. thanks for your advice

pentoncm

What kind of HU do you have, what xover slopes can you use? The slope and point makes a huge difference.

VR028

Jvc kd-r926bt

pentoncm

Sweet HU, you are lucky you live in Australia. SQ is coming back slowly in the USA, there has been a drought here for good mid level tuing HUs like you have.

You have an awesome crossover there, you are lucky. Set up your mids at 24db/octave at 60Hz. Set up your sub at the same setting 60Hz at 24db/octave. We can help you out here if you want advice on using the EQ. Make sure to get your sub time aligned, that really helps getting it up front.

VR028

ive got it set at 80hz at the moment. the clarions i have at the moment dont really like going that low so ill change it to 60hz when i get my new speakers. i just want to sort out the whole system first before i commit to buying anything. i might just get the mrx-m100 and polks seeing as how im going for a budget sq system.

pentoncm

VR028 wrote: »

ive got it set at 80hz at the moment. the clarions i have at the moment dont really like going that low so ill change it to 60hz when i get my new speakers. i just want to sort out the whole system first before i commit to buying anything. i might just get the mrx-m100 and polks seeing as how im going for a budget sq system.

I have the 6501MM components and they are awesome. They have amazing midbass. They currently go for $199 at onlinecarstereo.com which is a steal for them since they retail for $380. I am convinced they are the best bang for the buck at $200. Amazing midbass, nice midrange, and the tweeters are smooth.

I have my MM's set at 60Hz 24db/octave at the moment but that is for pure SQ purposes and because I have a sub. I have just played with the crossover and they do fine all the way down to 30Hz. If you dynamat the door and make sure that the holes in the door panel next to the speaker are covered, they will sound like little subs in your doors.

If you really want nice sound I would recommend getting the 6501's and a polk 4 channel amp and run them active off of the amp. It sounds much better when you ditch the passive crossover. Oh and disconnect the rears (This is a huge point of argument over all of the forums so its fine if you don't want to). Everyone is just used to rear speakers. When you go to a movie theater, dialogue doesn't come from behind you, only rare special effects. It messes up your imaging really bad by having vocals coming from 4 locations in the car.

VR028

yeah for me its a straight toss up between the mm6501's and morel maximo 6's. the rears aren't really a problem for me i cant hear them at all from the front because they're in the bottom of the rear doors.

VR028

another quick question have you heard of the JVC KS-AR800D?
heres a good review i found http://www.mobileelectronics.com.au/products/reviews/jvc_ks-ar8004_4_channel_amplifier/

how do you think it would compare quality wise to a pdx f4

is the f4 worth the extra money? online the jvc is $316 and the pdx is $484

pentoncm

JVC doesn't put out amps here in the states but that review looks good and I know its a solid brand for other types of electronics.

Keep in mind that SQ is not necessarily going to come from the amp. Most amps sound the same, it is the speakers and tuning that really make a stereo come to life.

VR028

thanks pentoncm your always very helpful. besides sq i also meant build quality although it does look like a solid amp judging from the internal pics.
ill go with the jvc then as there's no point spending money unnecessarily. thanks again

pentoncm

Play around the the placement of the subs in your trunk, the location makes a huge difference. Normally firing to the rear or to the side gives much better results than forward or up firing.

KaosTsoc

pentoncm wrote: »

JVC doesn't put out amps here in the states.......

Sorry pentoncm, but JVC does put out amps here in the states.

http://mobile.jvc.com/product.jsp?pathId=64

They also have their Arsenal site too, and that has amps there as well.

http://mobile.jvc.com/product.jsp?pathId=144

I think they been making amps here in the states for sometime now.

Thanks.

VR028

ive always had my subs firing toward the rear while pushed right back against the seats.
heres a pic of my old enclosure


and heres the new enclosure but with the old subs in untill i sort out a new amp, its not pushed back all the way though

pentoncm

KaosTsoc wrote: »

Sorry pentoncm, but JVC does put out amps here in the states.

http://mobile.jvc.com/product.jsp?pathId=64

They also have their Arsenal site too, and that has amps there as well.

http://mobile.jvc.com/product.jsp?pathId=144

I think they been making amps here in the states for sometime now.

Thanks.

Whoops, my bad. I didn't realize it cause I haven't heard of people talking about them.

KaosTsoc

No worries. I dont think anyone talks about them on here cause JVC has not always been a top notch brand. Kind of in the lines of Dual or something. However, they might have gotten alot better, and actually worth something now.


Thanks.

VR028

i changed the crossover frequency on my current clarions from 80hz to 60hz like you suggested and they sound fantastic. in my old car i always had them set at 80hz because anything lower made them rattle like crazy so when i transferred it all over to the new car i never bothered changing it. there is a small rattle on really bassy songs at high volumes but other than that its not bad for un treated doors.

its made a world of difference im tempted to actually keep them now

VR028

i just found polk db 1240's for sale in australia so i modelled them in my enclosure. interestingly they showed a nicer response curve.
should i trust the software and get db's or follow my ears and get mm's.
keeping in mind that on the sound board theyre both sealed and im using ported

pentoncm

The db subs are designed for ported, sealed, and bandpass boxes. The MM and SR both do better in sealed boxes. So I'm not surprised that the db looked better in a ported box. All in all I would go sealed with the MM, they are significantly better.

VR028

i had a listen to some more subs today. seems the polk mm will not suit my needs as i have a ported enclosure. i had a listen to orion xtr pro's, hertz hx 300 and phoenix gold ti2's. i was impressed by all but the phoenix really stood out in the low end. would you recommend any of those subwoofers?

pentoncm

I have heard the Hertz Hi Energy subs in a car and they sounded good. I don't know too much about orion but Phoenix Gold makes some great stuff.

Are you listening to these subs on a board or in a car? In a car they will sound completely different because of cabin gain.

VR028

all on the board unfortunately. its better than nothing i suppose. i didnt think much of the orion but they were being underpowered. the hertz was being run off a audison sr1dk and the phoenix of a ti 1500w amp. the pg sub really sounded powerful and had a lot of authority in the low end but the hertz sub was more musical and blended with the mids better

VR028

ok so ive decided on the hertz hx 300 so im going to team it with a jvc ks-ar9501d 1500w rms @ 1ohm.
little different to the original plan but this works out to be alot cheaper so thats a bonus