Phoenix Gold Phorum

Hey guys
I have one PG 1200.1 RSD amp. It is pushing one JL 12w7 which is 3 ohm single voice coil. Using the gain setting formula I estimated the output of the amp @ 3 ohm as 990 watts so sqrt (990 x 3) for a voltage reading across the speaker terminals of 54.5. I set up 2 dual 2 ohm RSDc 12's for this amp. Wired in series for 4 ohm/sub and final 2 ohm load into the amp which gives 1200 and sqrt (1200 x 2) for a voltage of 48.9. Both were read off a 60hz 0db test tone and both sub setups are in sealed enclosures (JL's suggested dimentions and the RSDc's 1.15 per sub).

PHEW! after all that my question is, why is the output on the JL setup way and I mean WAY more than the RSDc setup. the sub preout on the JL from the head unit was -11 (goes from -15 to +15) and the RSDc setup had to pump it to +7 just to get some kind of decent response. Am I missing something here? Any suggestions would be greatly appreciated.

Enclosure possibly? Also remember the w7 is a more capable sub output wise.

I think the rsd amp have more of an out put @ 4ohms then @ 2ohms. I thought their power supply is regulated to keep them from burning up. If so I would think ur losing like almost 30% power at 2 ohms than @ 4 ohms. Someone chime in w/ a full explanation on this. I thought PG went to the regulated power supplies around the late Ti or xenon lines.

I always thought the rsd 1200.1 would do around 1200-13xx in 2 ohm. From what I have read 1 - 1.25 cf is the idea for a 12" rsdc.

This is for 2 subs right?

Not sure if these formulas are correct, but at
775 w @ 4ohms = 55.67 volts.
1200w @ 2ohms = 48.98 volts.

Are these brand new subs?
Have you broken them in yet? I have read you need to break the subs in for 8-10 hours.

Maybe Stipud or bfowler or some of the other guys that have ran the rsdc's can chime in also.

Soth

I don't have an answer to your questions but when you describe how you wired up the RSdC subs, you mean that you wired the coils of each sub in series and then the two subs (the two series loads) in parallel to achieve your final two ohm load?

Was your sub preout set at the same place while tuning both sub setups? That is, was it at "0" during both tuning sessions?

knightrider358 wrote:I think the rsd amp have more of an out put @ 4ohms then @ 2ohms. I thought their power supply is regulated to keep them from burning up. If so I would think ur losing like almost 30% power at 2 ohms than @ 4 ohms. Someone chime in w/ a full explanation on this. I thought PG went to the regulated power supplies around the late Ti or xenon lines.

these are Class d amps and put out the most power at 2OHM's not 4OHM's....They are optimized to run at 2 OHM's with no problems at all.
Do not confuse them with Ti or Xenon amps as these are class A/B, they are not related. run them at 2OHM's if you want the most out of them. 4 OHM's is good for 850ish.

The only thing that changed between both setups was dropping the volt output from 54.5 down to 49 due to the formula. Both sessions the sub preouts/bass/treble/balance/fade were all at zero. The difference was in the way I had to change the sub preout level. The W7 output level had to be dropped to -11 where as the 2 RSDc's had to be pumped up to +7 to get even close. The W7 is currently in the sealed dimentions of the Power Wedge box design. The RSDc's are in 1.15 cubes per sub. And yes the subs were wired in series to get 4 ohm per sub then wired into the amp as a 2 ohm final load.

I changed the output voltage across the terminals to 52 and it increased the output of the subs a great deal but still not compared to the W7.
Is it possible that one 12W7 on 980 watts is that much better on output than 2 RSDc 12's running off 1200 watts?

Thanks again for all the input

yes it's possible. I have heard a W7 and it was very stout on very little wattage. i have not heard 2 Rsd's but aren't they supposed to be the end all be all of subs??? I would think they would be loud, they are receiving 650ish watts each so i dunno.

mmm May come down to the box again.. The 2 rsds should be louder. More power, and almost double the cone area should definately have an advantage..

More info on the box. The measurements are 11.5" x 12.25" x 13" which gives .93 cube after sub displacement. There is 1lb of polyfill in each chamber to give it the estimated 20% increase for a total of 1.12 cube each. It did seem that that was ALOT of polyfill for such a small enclosure but it did leave enough room for the sub to sit in the box without having to smash the polyfill down. Thanks for letting me pick your guys brain over this matter

knightrider358 wrote:I think the rsd amp have more of an out put @ 4ohms then @ 2ohms. I thought their power supply is regulated to keep them from burning up. If so I would think ur losing like almost 30% power at 2 ohms than @ 4 ohms. Someone chime in w/ a full explanation on this. I thought PG went to the regulated power supplies around the late Ti or xenon lines.

No, the Ti and RSD monoblock amps are optimized for 2 ohms. Only Xenon monoblocks were geared to run 1-4 ohm loads.

I have a 10W7 and an RSDC12. Sealed for sealed their output is about par. With my HO wedge box for the JL it is much louder, though I am not keen on the boomy sound that box makes.

It sounds like you had your gains set higher for the JL than they should have been. The way the formula works is that regardless of the impedance, you would have the same voltage. We know that when you double impedance, you get half the power, so...

sqrt(1500 watts * 2 ohms) = 54.8v
sqrt(750 watts * 4 ohms) = 54.8v

Check your subs to make sure they aren't wired out of phase with each other (+/- reversed on either sub). Also try flipping the phase on both subs by switching +/- at the amp to see if you get less cancellation with your front stage that way. That made a massive audible difference in my RSDC install.

Thanks for all the help. I reset the output voltage on the amp and the subs really came to life. The 2 12's are really hammering now and sound really tight and clear. I dont think the low notes excel as much as they do with the W7 but ive not broke the RSDc's in either. But at least they are putting out the power that you guys have been talking about
Once again thanks for all the input and hopefully ill have some pics posted on the install forum of the RSDc's pushing their surrounds to the limit

I have two 1200.1s on 1 15t" and it POUNDS. today i droped the ohm load n the rsd"s to 1 ohm to see if they could push at 1 ohm. sadly something happened to my 5 farad cap that i use as my amps distribution block and i didnt get to test em.

Not to high jack this thread but has anyone used any of the rsd line of amps at a 1 ohm load and had any issues other than heat??

KHPower wrote:I have two 1200.1s on 1 15t" and it POUNDS. today i droped the ohm load n the rsd"s to 1 ohm to see if they could push at 1 ohm. sadly something happened to my 5 farad cap that i use as my amps distribution block and i didnt get to test em.

Not to high jack this thread but has anyone used any of the rsd line of amps at a 1 ohm load and had any issues other than heat??

at ran my rsd1200.1 at 1ohm for about 6 months, never noticed any issues. ymmv.......