38 replies to this topic

[edy]

Hey guys,

Well I am pretty happy right now, I just picked myself up 3 PPI Art oldskool amps.

A1200.2 and 2 A600.2's.

Basically, what I wanted to know, what sort of loads you can put on these amps for everyday use.

What I am going to do is have the 600.2's bridged, running one to each side.

I was told they are stable to .5 or even .25 in stereo mode. Is this true? And if it is, would I be right in assuming they could bridge at 1 ohm without any trouble?

My plan was to bridge the 1200.2 at 1 ohm running into my newly acquired RE SX 15, then bridge each 600.2 at 2 ohms for each side of the front stage.

Sorry about all the questions, but if someone knowledgeable on oldskool PPI gear could help I would be thankful.

Chris

[jas]

they are suposed to be maxed out at 4ohm bridged

btw great amps love them to death.....try a a1200.2 on a set of dyns...its the most amazing experience or just do what you are going to do and use the a600.2 bridged up front


in 1996 and 1997 these were the biggest amps you could buy and the best by far. I bought my a1200.2 in 1997 its been the best amp ive owned by a long margin...and still the most powerful 2 channel amp used in my car to date.

in 1996 and 1997 there seemed to be not many or no subs designed for low impedences( 4ohms was very very common impedence for subs back then) and the ppi art seemed to be maxmimised to drive the jlaudio 12w6v1 (dual 6ohm) in a triple sub 4ohm combination.

everything that ive read about this amp was that it was designed to put out its most power into 4ohms bridged and roll back the current for half the power into 2ohms bridged (due to some internal circuitry..could be wrong but that is what the manual states)

anyway i know youll love the setup jsut try to maximise the load for 4ohms.

[edy]

yeah thats cool, the sub is dual 2 so I have no worries.

I wonder how accurate the 1200 rms figure is?

do you think it might be better running 1 coil per channel at 2 ohms?

edy

[HISPL]

edy said:

yeah thats cool, the sub is dual 2 so I have no worries.

I wonder how accurate the 1200 rms figure is?

do you think it might be better running 1 coil per channel at 2 ohms?

edy

It makes no difference either way.
The amp will see the same load.
When an amp is bridged each of the bridged channels sees half of the load.
A 4ohm bridged load is exactly the same as 2ohm stereo.
IMO it would be better to run the amp @ 4ohm bridged.

[edy]

Ok cool, that is what I will do then, thanks guys.

edy

[jas]

they will easily do 1200watts rms

about 1400watts rms is about all they will do approx...based on a us car audio magazine review of a ppi a600.2 (i think it was CA&E) amp review (including full specs measured at 1% and 0.1% thd)

just remember these are highly regulated...the difference between input voltage (10 to 14.4volts) is about 10watts rms output ..thats it

[fuddbutter]

these amp's are not 2ohm stable when bridged!

the 1200.2 was designed to put out 1200wrms at 4ohm when bridged. back when they came out the only sub's you could really get were 4 and 8ohm..

beutiful amps

let me know if you ever want to sell them, i want to build up my collection

[edy]

hmmm, well if they are not 2 ohm stable bridged, what should I do for my front stage.

I have BassyK's old Total Recoil 3 ways, currently wired in parallel at 2 ohms, is it possible to get a 4 ohm load out of them?

edy

[jas]

please explain why the split system would be 2ohm load

are you using 2ohm mids or midbass or are you using dual 4ohm midbass drivers???

OR are you using dual 3 way each side of the car???

[edy]

no the speakers dont have passive crossovers, they are indiviually capped, meaning that paralleling them together creates a 2 ohm load.

edy

[Damon]

Nah, if you have a woofer, midrange and tweeter the amp will only see each speaker within the bad it plays. I can't see how you would run a thre way set up without passive crossovers. Or maybe we don't understand what these speakers are. Still, you'll find that if playing above 100Hz there will be far less likelyhood of over current problems than below 100Hz.

[jas]

sorry edy still dont understand

not passively x-over...but they are individually capped???

not sure what you mean unless you only use series caps on each mid and tweeter...which i wouldnt do...oh well youll explain

[edy]

Its hard for me to explain because I dont fully understand how the caps work.

All I know is, BassyK ran them the exact same way I am, with awesome results.

Maybe someone who heard these and knows something about them can chip in, I need all the help I can get, I am really still quite a newbie in this sort of thing.

edy

[fuddbutter]

you can run the at 2 ohm stereo, then you will only need 1 x 600.2 thats 150wrms + each channel!!

(then sell me the other one )

[Bassaholic]

They don't really provide a 2 ohm nominal load - as Damon explained, the amp will only see each speaker within the band that it plays.

If they are not matched up properly (ie if they provide a ~2 ohm load over a significant part of the frequency range) - if there is significant uncrossed over overlap in the frequency response then they will tend to sound rather nasty.

I guess its technically possible (however unlikely it sounds) just to use caps - if the inductance of the drivers is significant to raise the impedance and roll off the high end of each driver significantly enough to blend in properly. (as well as the acoustic roll off of the speakers...)

But surely there are both caps and coils (and maybe some resistors) in the crossover right?