Right now I'm pushing to 12" Xplods with a 500X 4 chan amp..
it runs alright..
I'm selling that one and upgrading to one with the 18db boost @ 45Hz, which would be

550X - 4 chan (275x2 - 4ohms bridged)
500S - 2 chan (250x2)
500BD - Mono Channel (500x1)

My question is, which one is the best? Is there a big difference between a mono channel and a 2 or 4 chan amp? I mean, does the bass get deaper or something? I hear good results from the 500X.. WHAT'S THE DIFFERENCE??

and don't say spend the extra $20 fro the BD.. forget that.. I just want to fully understand the difference between pushing the same amount of bass, but just a different class of amp, and different channels..

THX

If I remember correctly, Mono amps are class D. When you run a 2 or 4 ch amp bridged you are generally putting more strain on the amp. If I am wrong about these I am sure someone will let us know

Brian

well the main thing about a digital amp is the fact that they are more efficient than most other amps, and that makes them able to run at lower impedances that would melt most other amps,

i know a guy running a 500bd on 4 he2 12's in the back of an S10, at 1/2 ohm. as far as i know, he hasnt had any problems.

you wouldnt be able to do that with a non digital amp, for the most part.

however, the class D amps, have a clip in the signal, hard to describe, but it is a flat spot in the sound wave.

consequently, that same flat spot in the wave, is why you dont use class d amps for mids/highs, you can hear it in higher frequencies, but not (for the most part) in the bass.


adam

but to the non competition ear, you can't notice a difference in the sound?

in my opinion, you can hear it, but if the bass is REALLY LOUD like it can be with low impedances and multiple subs, i doubt anyone would ever notice.

i personally use a class D amp.

on mids and highs, it is VERY audible.

adam

that sounds pretty stupid to do. im pretty sure that a bd500 is only 2 ohm stable. oh well, not my money.

well, he doesnt have to worry about "warranty" issues.

and it is a common known fact, Rockford BD series amps will handle 1 ohm loads indefinitely without any problems.


adam

common known fact huh? if you say so. what does a 500bd put out at 1 ohm?

fosgate recommends no lower than 2 ohms on their site. but i guess if you have enough ventilation, anything is possible.

disclaimer:
not all things are possible in the above hypothesis; i.e. legacy amps will not last long at anything below 2 ohms or in some cases, above it either.

well most of the bd500's that ive seen have done 540+ rms @ 2 ohms.

based on the efficiency of the amp, id say most likely about 900rms.


adam

yea, I've seen 1000BD push @ 1ohm.. they still work well

another quick question.. well.. 2
my decision is between the 550X which pushes 275x2 and the 500BD which pushes 250x2, will I miss that 25 W if I go with the BD?

the second.. when I have my bass on loud for a while, it cuts out.. I can't seem to figure out why.. is it just because of the heat? all the wiring is perfect.. ground is excellent.. it happens mostly on humid days.. could that be?
and what would I do to fix it?
just raise it an inch off the floor so it vents better?
thx

No you won't miss it. It takes twice as much power to hear a difference (3 dB). If you were deciding between 275 watts/woofer, or 400+ watts, then it would make a difference.

Quote:
the second.. when I have my bass on loud for a while, it cuts out.. I can't seem to figure out why.. is it just because of the heat? all the wiring is perfect.. ground is excellent.. it happens mostly on humid days.. could that be?
and what would I do to fix it?
just raise it an inch off the floor so it vents better?
thx

If this is the way you normally hook stuff up,
then you answered your own question.

i have too. but we werent talking about a 1000bd, we were talking about the 500bd.

if its cutting off, its probably getting too hot. it either doesnt have enough ventilation, or you are running it too low a resistance.

I'm just running my amp bridged right now
so 4-ohm per channel 250W/channel..
so I can't see it running on too low of an impedance..

it's a four channel amp.. 125x4 - 250x2.. makes sense..
does it make a difference if the amp is screwed to the floor or not?
to me, it wouldn't make a difference because there's no moving parts and therefore nothing to skip

the bd500 is a mono block amp.



adam

yes, thank you
but the amp I'm running is a 4 channel it's the 500X

but it doesn't matter anymore, I just blew the amp, well, I think I did

I was just driving and it crapped out, now nothing works..
good thing for warranties :lala:

what ohm load are your subs? 8 ohm subs get a 2 chan and bridge it. 4 ohm get eithr a 2 ohm stable mono block or a 4 chan. BTW I almost always bridge subs but if you do not you will have a little better SQ.

usually the higher the resistance, the better the sound. speakers wired at 8 ohm will usually sound better than speakers wired at 4 ohm. just a little FYI.

basically the speaker with more resistance gives the amp more control over the woofer's movement, so less resistance = less control = more sound @ lower Quality


adam

but if you run your subs @ a higher impedance, it's taking away power to the sub (hense resistance).. therefore, you're subs aren't sounding loud..

if I wanted clearer bass, I would've went with 10s.. but I wanted bigger, badder bass.. so I stuck with 12s

I'm running them @ 4ohms bridged.. exactly how the manual for the amp told me to wire them..
2 channels driving 1 sub.. gives me 250W x 2 subs..
the amp should've been able to handle that kind of power, but I guess it didn't .. which is why it blew

so they are 4 ohm speakers? The speaker(s) sets the ohm load not the wireing.

I disagree..
if you wire in parallel, you are wiring two 4-ohm speakers at 2 ohms.. three 4-ohm subs @ 1.3 ohms.. three 8-ohm speakers @ 2.67 ohms..

THE FORMULA 1/R = 1/R1 + 1/R2 + 1/R3 + etc. ("R" = ohms) EXAMPLES Say you have two 4-ohm enclosures, an 8-ohm enclosure and a 16-ohm enclosure all in parallel. Of course you would never do such a thing because the lower-impedance speakers will get more power and be louder than the others (you figured that one out yourself, right?), but this is just an example. The solution goes as follows: 1/R = 1/4 + 1/4 + 1/8 + 1/16 = 4/16 + 4/16 + 2/16 + 1/16 = 11/16. Therefore R/(1) = 16/11 = 1.4545 ohms. If you're not into finding "lowest common denominators", just get out a calculator and turn everything into decimal equivalents as follows: 1/R = .25 + .25 + .125 + .0625 = .6875 Therefore R/(1) = 1/.6875 = 1.4545. To keep life as simple as possible, most people put enclosures of the same impedance in a parallel circuit. If you do this it's all just a matter of dividing that impedance by the number of speakers. Example; four 16-ohm loads in parallel = 16/4 = 4 ohms. Similarly, two 8-ohm loads in parallel = 8/2 = 4 ohms. The following is a quick reference listing of some commonly used parallel loads: ("R" = ohms) 2 x 16R loads = 8R 2 x 8R loads = 4R 2 x 4R loads = 2R 3 x 16R loads = 5.33R 3 x 8R loads = 2.67 R 3 x 4R loads = 1.3R 4 x 16R loads = 4R 4 x 8R loads = 2R 4 x 4R loads = 1R.

if you wire in series, you are wiring two 4-ohm speakers at 8 ohms..

go here for more details
http://www.rockfordfosgate.com/rftech/wiringwizard/

forgot to finish what I started..

so anyways, it DOES depend on how you wire your speakers, but I do agree that in PART, the speakers do determine the imedance at what the amp is running as ASWELL as the wiring..

do it with 8ohm speakers and you get a 4 ohm load. Wireing affects the ohm load seen by the amp but it is ultimately detremined by the speaker.

I'm not gonna argue..
it's a mixture of both..

i dont see what the discussion is about. you both seem to be saying the same thing but saying the other is inaccurate. either that or there is some confusion. i know im getting confused just listening to this. heres how it is:

wire has one purpose: give electricity a means to travel from point A to point B. wiring in turn really has nothing to do with resistance (strangly enough there is resistance in the wire, but thats another story). the only thing that changes how the amp sees the load is what order you put the resistances (voice coils of the speakers) in. you really cant connect speakers to amps practically without wires, but that doesnt mean that wiring is what changes the load.

see now im confusing my self. lets just pretend this conversation never took place and call it even. this really doesnt matter since we know how to wire things up to get what we want. lets just leave it at that.

And I refuse to have a battle of wits with an unarmed opponent.

how old are you man?
grow up dawg..

I stopped.. but you kept looking for it

do I have to stoop to your level and start with the 'yo mamas'??

leave it be..

ok, everybody is happy. we will stop this here. any other personal conversations should be kept in pm's.