Printer Friendly Forum Posts - any advice on good 4 ch amp

i used to have a black ice 1800 watt bass amp and it sounded pretty nice and i remember the specs on the 4 channel amps to be pretty clean too but the early black ice amps had a serious durability problem. maybe they have fixed some of the issues with them but if you get the black ice amp id make sure you have some sort of warranty, at least a year. ive never really been a fan of rockford fosgate but in this case if i had to choose one of those id probably go with the rockford.

Cool! Thanks! For the sub I am thinking of going with the kicker cx300.1D is there any better alternative for $100-150 bucks? Btw is 8 gauge power wire good enough for this power rating?

8 gauge should be fine if you run a dedicated 8 gauge power wire for each amp. if you plan on just running a single power wire and then splitting it off to each amp with a distribution block then i would recommend running a single 4 gauge wire from battery to distribution block and then you can use 8 gauge from the D-block to each amp.

if you just run a single 8 gauge to run both amps then you are really pushing the capacity of that wire and could end up burning the wire over time. it is never a bad idea to over size your wire just to make sure you cant overload the wire, and a side benefit of over-sized wire is that if you ever upgrade your system to something more powerful then chances are you wont have to run new wire.

a single 8 gauge wire is good for up to 60 amps of current or approximately 800 watts on a typical car audio system. so if both of your amps are in the 300 - 400 watt range then the wire is almost maxed out, that is why i recommend using 4 gauge just to be safe.

Cool! Thanks for your great tips! I have done a lot of reading & now debating whether I should stick with class A/B or go with class D. What is your opinion?

class D amps are over all more efficient than a class AB. this means they are usually smaller in size and lighter because they require less cooling and use components that arent as heavy duty as a class AB 4 channel amp. class D technology in a high frequency amp is a relatively new thing to the car audio world compared to class AB which has been around forever so the class D amp might cost you a good bit more than a class AB with about the same specs. its really up to you which way you go because there is really no advantage to using a class D amp under 500 watts vs a class AB amp.

I have decided to go with the new Pioneer GM class D amps! What you think? I wanted to try a 4 ch Alpine PDX but too pricey & if level match tthey could sound the same!

i used to have an alpine PDX F4 amp on my front components and i can say with confidence that that amp was the best sounding amp ive ever heard. the pioneer amp seems like a decent amp although it is a stranger design, class FD? not simply class D but a combination of class designs. this amp might not sound that great even though it claims a good distortion rating of .05% but keep in mind that the alpine PDX distortion rating is .005% which is 10x lower by comparison. im not sure which size amp you were looking at but the one i saw was a 600 watt amp and recommended you use 4 gauge copper wire just for that amp so keep that in mind that you will now not be able to run 8 gauge wire.

Now I am considering the pdx-f4 or the jl audio xd500/3? How do you think the jl will compare to alpine?Have you heard the jl xd series?

i have not heard the xd series on regular speakers ive just heard one once on a set of subs, but just comparing the specs the alpine should be a much cleaner sounding amp. the JL amps that compare the most to the PDX amps are the JL HD series which are actually a tad bit cleaner than the alpine but its almost double the price. once again id take the alpine...

Cool! Can I message you to see if I can get amp through your store?

i dont have a store anymore, even if i did i never sold alpine products. what made you think i had a store? im just curious unless you you went back and looked at some of my old posts i cant see how you would have known that

Oh ok! I went on Amazon.com & saw a seller that has Alpine products. The seller was: Sound n Security. So I thought It might be you!

Btw would you get a PDX-F6 or PDX-F4 & MRV-500? The one amp would be an easier install.

haha ok, yea that amazon seller is not me... thanks for clearing that up because i was more than a little confused.

im not understanding the way you listed your options man, both the pdx amps are 4 channel amps so how would either way be an easier install? either way you still need two amps, one for the highs and one for the bass. the difference between the F4 and F6 is just the power output, otherwise they are the same.

soundnsecurity wrote:

haha ok, yea that amazon seller is not me... thanks for clearing that up because i was more than a little confused.

im not understanding the way you listed your options man, both the pdx amps are 4 channel amps so how would either way be an easier install? either way you still need two amps, one for the highs and one for the bass. the difference between the F4 and F6 is just the power output, otherwise they are the same.

I thought pdx f6 can be bridged to 3 ch. anyways whats better a 4 & 2 ch amp or one good 3 ch amp & let deck power drive the rear door speakers. Will use onevsealedc10 inch kicker comprt sub.

oh ok, i was thinking you needed 4 channels plus bass. really both the PDX F4 and F6 can be used as a 3 channel as long as the power output is enough.

to be perfectly honest, if you planned on running your back door speakers off of the deck and run the front off of an amp then you might as well not have back speakers at all because you wont perceive the back speakers over the much louder front speakers. personally i could care less whether i run back speakers at all. the last two cars ive had i disconnected them and just concentrated all of my effort up front and it always sounds awesome if you do it the right way. people put so much emphasis on back speakers but they really are not helpful to anyone listening in the front seat. i tend to not waste money trying to power or upgrade back speakers that only serve to drag down the sound quality of the front speakers.

so i guess the moral of this story is if you arent going to amp all speakers then dont even run the speakers that will not be on an amp. and to answer your question, it would be better to have a 4 channel and a separate bass amp. but if you want to scrap the back speakers after hearing what i just said then a single 3/4 channel amp will do you just fine.

soundnsecurity wrote:

oh ok, i was thinking you needed 4 channels plus bass. really both the PDX F4 and F6 can be used as a 3 channel as long as the power output is enough.

to be perfectly honest, if you planned on running your back door speakers off of the deck and run the front off of an amp then you might as well not have back speakers at all because you wont perceive the back speakers over the much louder front speakers. personally i could care less whether i run back speakers at all. the last two cars ive had i disconnected them and just concentrated all of my effort up front and it always sounds awesome if you do it the right way. people put so much emphasis on back speakers but they really are not helpful to anyone listening in the front seat. i tend to not waste money trying to power or upgrade back speakers that only serve to drag down the sound quality of the front speakers.

so i guess the moral of this story is if you arent going to amp all speakers then dont even run the speakers that will not be on an amp. and to answer your question, it would be better to have a 4 channel and a separate bass amp. but if you want to scrap the back speakers after hearing what i just said then a single 3/4 channel amp will do you just fine.

Yeah I might not run the back then. I was worried it would sound weird with no back fill. But you got a point that the quality of the woofers won't be the same as the front & maybe actually colour the sound with deck power & even amp power. Btw do you know what the amp 3rd channel gets in 2 ohms with the F 4 & F 6?

PDX amps maintain the same power in either a 4 ohm or 2 ohm load so their bridged power for the 3rd channel should be 200 watts for the F4 and 300 watts for the F6. but the typical rules still apply i think that the lowest ohm load you can run safely on any two channels bridged is 4 ohms. so your subs cant be below 4 ohms total to be ran on the bridged 3rd channel.

i dont know if you might be confused on how amps work but ill just go ahead and explain anyway that using a 4 channel amp like it is two separate amps is not like having a single 2 channel amp and a single mono bass amp. mono amps are designed a little different so that they will run safely down to 1 ohm or less and your usual multi channel amp wont run lower that 2 ohms per channel, also referred to as stereo, or 4 ohms bridged(mono).

so if you already have your subs then you need to take that into consideration that the ohm rating of the subs might make you not be able to get the maximum power from the amp. does that make sense to you or should i give you an example?

soundnsecurity wrote:

PDX amps maintain the same power in either a 4 ohm or 2 ohm load so their bridged power for the 3rd channel should be 200 watts for the F4 and 300 watts for the F6. but the typical rules still apply i think that the lowest ohm load you can run safely on any two channels bridged is 4 ohms. so your subs cant be below 4 ohms total to be ran on the bridged 3rd channel.

i dont know if you might be confused on how amps work but ill just go ahead and explain anyway that using a 4 channel amp like it is two separate amps is not like having a single 2 channel amp and a single mono bass amp. mono amps are designed a little different so that they will run safely down to 1 ohm or less and your usual multi channel amp wont run lower that 2 ohms per channel, also referred to as stereo, or 4 ohms bridged(mono).

so if you already have your subs then you need to take that into consideration that the ohm rating of the subs might make you not be able to get the maximum power from the amp. does that make sense to you or should i give you an example?

Ok I hear yah! I might need separate sub amp then as my kicker compRT 10 inch sub is 2 ohms nominal. What do you recommend that is around 300wX1? Maybe MRV-M500!

I just read pdx spec sheet it seems that bridged for sub it could be 300w into 4 or 2 ohms. Or am I wrong?

Also in bridge mode the data sheet always say stable into 4 ohms but they refer to 300x2 not 300x1. What you think?

it says 300x2 because you can bridge each set of channels, but you will only be bridging the last pair of channels (channel 3 and 4)and it will give you 300 watts assuming you are talking about the F6, and then that will leave channel 1 and 2 to power your front speakers.

flm09] wrote:

I just read pdx spec sheet it seems that bridged for sub it could be 300w into 4 or 2 ohms. Or am I wrong?

no, in bridged mode it will only allow as low as 4 ohms. it seems odd at first but the reason for it is that each set of terminals is actually wired to work together internally. so when you wire a set of 2 ohm speakers to each channel( 2 ohm stereo)or a single 4 ohm speaker in bridged mode, the amp does not see a difference because the amp will total the ohm load from each channel when used in stereo mode. so to the amp two 2 ohm speakers gets wired together internally for a total 4 ohm load at inside the amp.

likewise if you use a set of 4 ohm speakers on each channel then the amp would consider that the same as if you had used a single 8 ohm speaker in bridged mode. its harder to understand the difference with this kind of amp because it produces the same amount of power into each ohm load, but if you look at a more conventional amp whose power goes up and down with the ohm load then it becomes a bit easier to understand whats happening.

soundnsecurity wrote:

flm09] wrote:

I just read pdx spec sheet it seems that bridged for sub it could be 300w into 4 or 2 ohms. Or am I wrong?

no, in bridged mode it will only allow as low as 4 ohms. it seems odd at first but the reason for it is that each set of terminals is actually wired to work together internally. so when you wire a set of 2 ohm speakers to each channel( 2 ohm stereo)or a single 4 ohm speaker in bridged mode, the amp does not see a difference because the amp will total the ohm load from each channel when used in stereo mode. so to the amp two 2 ohm speakers gets wired together internally for a total 4 ohm load at inside the amp.

likewise if you use a set of 4 ohm speakers on each channel then the amp would consider that the same as if you had used a single 8 ohm speaker in bridged mode. its harder to understand the difference with this kind of amp because it produces the same amount of power into each ohm load, but if you look at a more conventional amp whose power goes up and down with the ohm load then it becomes a bit easier to understand whats happening.

Ok got it! Now I am looking for a 2 ch amp and a mono amp. Do you think separate amps are better than one single 3 ch amp?

either setup would be just as good as long as the single 3 channel amp was a good match to power both the sub and regular speakers. if the amp you choose has enough power for everything you want powered then id go with it mainly because a single amp will keep your system simple and clean. less chance for something to break and less money you have to spend and less work you have to run.

soundnsecurity wrote:

either setup would be just as good as long as the single 3 channel amp was a good match to power both the sub and regular speakers. if the amp you choose has enough power for everything you want powered then id go with it mainly because a single amp will keep your system simple and clean. less chance for something to break and less money you have to spend and less work you have to run.

True but now I am limited by my 2ohm subwoofer. Btw is there any two ch A/B in same price range as PDX that has better SQ than PDX?