Older Alpine Deck and EX365 / 368s

naustin

I've got an older Alpine deck rated at 35W x 4 which I'm planning to use to push my brand new 365 and 368s.

I also have a pair of 12" Kicker Comps in a sealed box, pushed by a 4 channel, 400 watt amp.

What I'm wondering is whether I'm going to need another amp to push my new Polks in order to keep up with the subs and not damage them. I am going to use bass blockers on both the 365s and the 368s, so that should help at high volume; but I'm concerned that the low RMS of my older deck will result in distortion at high volume.

What do you think?

sntnsupermen131

may i suggest the rockford fosgate punch 250.2 to run the 365s and 368s
deck power is 35 x 4
thats like 12 x 4 dirty watts in reality
those speakers are rated at 50-70 watts...somewhere around there
so the deck would not push those speakers and when you turn it up theyll distort
that amp probably runs 200 bucks on carstereotime.com
the punch 160 will probably push them decently too
that amp will probably almost push out 200
dodge...what do you think?
-Cody

PoweredByDodge

since you asked....

two choices -- you can either get a 4 channel amp, or you can get a 2 channel amp that is 2 ohm stable (so you'd run two speakers off each channel... like your front and rear on the left side would run off the left channel, front and rear on right side run off the right channel.)

note - all prices from crutchfield.com -- ebay them and you'll find em cheaper.

2 channel amps that'd do the job...

Pioneer gmx572 --- 100 x 2 at 2 ohms (50 to each speaker) --- price = 150 bucks

Fosgate 201S --- 100 x 2 at 2 ohms (50 to each speaker) -- price = 150 bucks.

cheap ones...

US Acoustics USB 2080 - 140 x 2 at 2 ohms (70 to each speaker) --- price = 89 bucks
(note - this is probably the one i'd go with, unless you choose a 4 channel -- you can't beat 90 bucks for 280 watts.)

4 channel amps to look at...

US Acoustics USB 4065 -- 65 x 4 at 4 ohms .. price = 129 bucks.

Pioneer GMX 574 --- 50 x 4 at 4 ohms... price = 230 bucks

that's about the best you can do for 200 bucks or less... unless you want to put in some effort and dig around ebay and internet for sale ads and find a used Optimus 400XL -- its a radioshack amp, but i've had one for like 5 years now and the thing runs like a tank... its "rated" at 65 x 4 at 4 ohms and 14.4 volts, but we metered it at 13.8 volts and it did over 70... the two ohm power is like 107 x 2... retail price was 179 bucks... you can find them used for like 50 - 100 bucks. only problem is they do not have a high pass crossover, so you'll have to use Fmods (bass blockers really do suck unless you make your own at 100 hertz that are 2nd order).

naustin

Thanks guys, especially for the amps you listed. I pretty much new I was going to need another one, and I was hoping someone would post a model that's a good value for this job. :cool:

Dodge, are you saying I should leave the Bass Blockers out entirely, or that I should use some other brand? The ones I've got are the 150hz jobs from Crutchfield.

naustin

PoweredByDodge

regarind bass blockers -- you gotta understand what you're dealing with here...

a crossover or bass blocker does not just hack off the unwanted music like a pair of scissors... it "fades" it out slowly over the entire frequency band.

a true "crossover" is 12 to 18 db's per octave (usually)... this is a pretty "sharp" or "quick" cutting off of the unwanted frequencies... so basically you can get everything you want (like from 80 or 90 hertz and up) and very swiftly cut out everything you dont want.

now this crossover i've just described is often included as a part of many amps.. its a knob that you can switch "high / off / low" -- high being what you'd use for your speakers.... off being that it allowed all frequencies.... low being that it would allow only the stuff below the crossover point (the bass) to your subs or whatever. but some amp's dont come with them... in which case you'd want to buy a set of Fmod plug in x-overs. This could become tricky as they only come in 70 and 100 hertz varieties.. not the 80 - 85 that'd be "perfect" for your highs.

so what is a bass blocker? how does it compare to a crossover? well a bass blocker is a 6 db per octave crossover. this means it "fades" with much less precision.. it takes longer to cut out the bass... basically... if you want to cut out ALL bass below 70 hertz...then you can probabl use like an 85 hertz 12 db / octave crossover. taht would do the job.. but if you use an 85 hertz 6 db/octave bass blocker, it will probably allow bass all the way down to 40 hertz before it cuts out. So in order to "truly" cut out at 70 or so, you have to use 150 hertz bass blockers... this means that at 140, 130, 120, 110, 100, 90, 80, and 70 hertz your sound is going to be steadily decreasing, which gives you a **** sound overall... it kills the punchyness of your speakers. But if you used a crossover you'd actually find that if you set it for 85 or 90, that you'll only see a reduction in sound from 90, 80, 70.... and all your 100 - 150 band of sound is still "fully in tact".

i think the easiest way for you to get around this whole difficulty is to get an amp that has the high pass crossover built in.. that way you just flip the switch, forget about the bass blockers, and sit back and enjoy good sound...

of the amps I suggested in the last post, the following have built in high pass x-overs....
1- fosgate 201S ($149.00 -- 2 channel)
2- US Acoustics USB 2080 ($89.00 -- 2 channel)
3- Pioneer GMX-574 ($250 -- 4 channel)

also -- they are somewhat "inferior" amps.... but you're not trying to drive 400 watt speakers here so they may be perfectly fine for ya -- Clarus / Profile make a couple of 4 channel amps that are like 150 - 175 bucks that have built in high pass crossovers. they do between 50 x 4 and 75 x 4 watts. I'm not really a fan of Profile's amps, but don't let my brand bias hold you back... if one of them is rated 75 x 4, it's probably like 60 x 4 in reality, which is the power that you were looking for so that's good... and its got the high pass crossover (which you'll be a HELLUVA lot happier with than 1st order bass blockers)
--Profile CL440 ($150) 50 x 4
--Profile CL640 ($180) 75 x 4
--Profile CA440 ($130) 60 x 4
--Profile CA640 ($160) 75 x 4

the others do not have a built in xover and would require a 30 dollar pair of RCA plug in Fmod crossovers or you could build your own "2nd order" passive bass blockers. a 2nd order bass blocker has the same "slope" as a crossover (the two words crossover and bass blocker are actually teh same thing but i'm using them separately to show the difference between the conventional store bought 6 db/octave bass blocker and the RCA line crossovers or 2nd order bass blocker crossovers). if you visit http://www.the12volt.com you'll find that they have diagrams and part selectors for constructing your own 2nd order [12db/octave] or even 3rd order [18db/octave] crossovers from inductor coils and mini capacitors that can be bought at radioshack... enough parts to do 4 sets of blockers would run you like 15 - 20 bucks if you didn't break anything first time around and were good with a soldering iron.

goingganzo

i will go with the ppi 2200 power class amp around 500bucks
50x4 at 4 ohms at .003thd and 100x4 at 2 ohms this is a sweet as hell amp.

naustin

Dodge, thanks for the awesome post. You just tripled my knowledge of Amps/Crossovers! :tup:

I'll definatly be leaving the bass blockers out and buying a new amp. Or Maybe two!.

The 400Watt Amp I have right now is a jensen xa 4100..:rolleyes: It puts out 50W RMS X 4 at .08 THD . Bridged into my subs right now, it is doing a solid .1 THD


I'm not sure how bad that is, but I take it from Gonzo's post that .003 is really good, and therefore .1 must be incredibly terrible.

Thanks again Dodge

PoweredByDodge

actually.. 0.1 is not bad... ppi amps are like very high end.... thats why they cost 500 - 750bucks.

MOST 2 or 4 channel highs have ratings that are either the same or double that of your Jensen. that jensen really doesnt sound too bad at all.

my two 1250 watt mtx 81000d's have 1.3 and 1.7% thd respectively (that's a WHOLE Lot more than 0.1%) but with subwoofers you really can't tell that much... i'd like it lower but oh well... for subs, you want something at or below 1% and you're safe... for highs... at or below 0.2% will be ok... but if u can afford at or below 0.1% you're in even better shape.

naustin

Sweet!