Disappointed in 2500d


Bronze Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 36
Registered: Jan-05
I replace four RF301m amplifiers (one for each sub) with the 2500d.
Its loud but lacks the something in the bass.
The RF301m seemed to have more impact with the 10s hit...
i am thinking about removing the 2500d and reinstalling my 301m's

i have tweaked the 2500d settings for over a month and cannot get the same quality of bass the 301m's provide with the same subs/box/deck


1997 Jeep Grand Cherokee w/5.2liter
120 amp alternator (already upgraded from stock 90amp)
Alpine 9833 control unit w/3 4 volt pair of outs
Biggest battery i found at Schucks (not optima)

4X MTX81044a DVC wire to 1.3ohm
1X Orion 2500d
1X RF301x (front door 600cs and dash 1001t infinity)
1X JVC AX4750 (rear door 6000cs Infinity)
4X 6000CS Infinity (each door)
2X 1001T Infinity
4X .5 farad caps (one for each 301m)

4 way Distribution/fuse block (aka door block)
2 way Distribution/fuse block (aka sub block)
0g running from battery to Sub Block (17 feet)

4g running from Sub Block to Door Block (1.5 inches)
4g running from Sub Block to Farad 1 pos
4g running from Sub Block to Farad 3 pos
8g running from Door Block to JVC amp
8g running from Door Block to MTX amp

4g running from farad 1 pos to farad 2 pos =Cap Bank 1
4g running from farad 3 pos to farad 4 pos =Cap Bank 2

4g running from Cap Bank 1 to 2500d power input 1
4g running from Cap Bank 2 to 2500d power input 2

12g runs for all speaker wire


Gold Member
Username: Carguy

Post Number: 2205
Registered: Nov-04
Just curious, what were your settings on the amp? Were you using 4 .5F capacitors with 2500D? What speaker ohm load were you using with the amp? 4ohms? 2ohms? 1ohm?
The capacitor size at 1ohm load on 2500d should be at least 3F (1F per 1000w peak).
Depending on your volume level, class D will sound as good as AB.
The only time when you will notice any difference is at high level. I've done numerous tests with my system too, class D 1800w rms vs 1500w rms class AB (Orion 275G4).
At normal listening volume, they sound pretty much the same, but as you increase it, the bass is a bit smoother and tigher on AB.
Have you looked at Orion's HCCA 275G4 amp? It is 1200w rms @ 12v, but you get more than 1500w in the car. That amp will and should perform better than 2500D amp. You can even compare with 301Ms cause they are both same class.
If you really don't like 2500D amp, I am sure someone with 275G4 amp might trade.

Bronze Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 37
Registered: Jan-05
I should have taken your advice to begin with Isaac...

you suggested HCCA, Zapco or US Amps.
While looking into Zapco i came across the 2500d for 600$ brand new (you get what you pay for!)

I will check the settings on the 2500d this morning and post them (after stopping in every parking lot in seattle to turn each nob just a bit i no longer recall thier exact setting)...

I have the four .5 Farads wired in two pair (farad 1&2 = 1 farad, farad 3&4 = 1 farad) because the 2500d has seperate power inputs. I have the first pair feeding input 1 and the second pair feeding input 2.

The subs are in two dual chamber sealed boxes and wired to 1.3 ohm (T81044a 4ohm DVCs. each sub is wired in parallel then each pair in series)

i am often hitting 30 on the volume dial of the 9833 deck and it is above about 22 that i begin detecting the lack of punch in the bass.

can a single 275G4 power four 10" 4ohm DVC 400/800 watt subs?
will it be a problem if i add two more 10s (once i figure out how to fit them the jeep)

Gold Member
Username: Carguy

Post Number: 2211
Registered: Nov-04
Orion 275G4 is 1ohm stable bridged and .5ohms in stereo. So you shouldn't have any problem as long as you stay within those limits.
Unlike most 1000w amps, G4 actually delivers and much more. I should know cause I have 2 of them, and 3 250G4s. I know I went a bit overboard, but at least I won't be needing amps in the future. :-)
BTW, most of the 275G4s sold for $400 or less.

Bronze Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 39
Registered: Jan-05
i am looking at a pair of 275G4s and see a couple other HCCA amps.
Would a HCCA 425 or HCCA 2100 be better than a HCCA 275g4?

How does the rated 300w of the 275g4 rate compared to the 1200w of the 2500d?

Bronze Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 41
Registered: Jan-05
my settings on the 2500d are as follows:
Gain at 1/3 turn
Low pass crossover is 4th order (24db per octave) slope and 90hz
High pass crossover is 2nd order (12db per octave) slope and 35hz
IntelliQ (boost) is 2db

i have the front and back door amps set to All Pass and rely on the Infinities passive crossover.

Gold Member
Username: Carguy

Post Number: 2231
Registered: Nov-04
If your system comes with active crossover, then HCCA 2100 will work great. If not, then stick to 275G4. It is not 300w rms. It is over 1500w rms @ 1ohm. If you could afford couple of 275G4, then you are set for life. Those 2 babies will either make your ears bleed or blow something up in your car.
Your current alternator will not be enough. Unlike 2500D, G4 is class AB and it will eat up lot of current. For that, you get very powerful sound.

Bronze Member
Username: Invictuz

Seattle, Wa Usa

Post Number: 42
Registered: Jan-05
good info thanks!
i recently discoverd that the standard casing for the alternator in the Grand Cherokee can only hold up to a 205amp producing alternator.

So i am looking at modifying the brackets and installing a GM Delco CS144 (260 amps running / 150 amps idle)

thanks again
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