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Quick review here. I got this for my wifes car and it replaces an old Rockford Power 300 which replaced a ppi 2120 and a 2360. Infinity ref 6.5 components and 2 ref 10's. System is not the best but my wife likes it.

Got this from woofers etc. Shipping was quick but thats expected as I live 15 min from them. Everything was packaged well. What surprised me the most was the size of the thing it is pretty small.

Install was pretty easy only complaint are the phillips screws to hold the wire in and the slot to get a screw driver into for the upper connectors is quite tight. I would rather see allen screws.

With everything in place the amp fired up with no problems. I set the gains really quick by ear and off we went to grab some dinner.

Listening to the amp I was impressed by how much more dynamic everything sounded compared to the old rockford amp. Much more headroom! Everything sounded much cleaner and the noise floor was much quieter.

I really like the amp and want to trade out the amp in my truck (MB quart onyx 4.125) for one of these. The amp does its job and for the price I highly recommend it.
 

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the darkside is loud
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Quick review here. I got this for my wifes car and it replaces an old Rockford Power 300 which replaced a ppi 2120 and a 2360. Infinity ref 6.5 components and 2 ref 10's. System is not the best but my wife likes it.

Got this from woofers etc. Shipping was quick but thats expected as I live 15 min from them. Everything was packaged well. What surprised me the most was the size of the thing it is pretty small.

Install was pretty easy only complaint are the phillips screws to hold the wire in and the slot to get a screw driver into for the upper connectors is quite tight. I would rather see allen screws.

With everything in place the amp fired up with no problems. I set the gains really quick by ear and off we went to grab some dinner.

Listening to the amp I was impressed by how much more dynamic everything sounded compared to the old rockford amp. Much more headroom! Everything sounded much cleaner and the noise floor was much quieter.

I really like the amp and want to trade out the amp in my truck (MB quart onyx 4.125) for one of these. The amp does its job and for the price I highly recommend it.
Thank you for the review!
How about some pics so we can see it for reals? :D

Bret
PPI-ART COLLECTOR
 

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I'm glad to hear this about the 900.4. I got mine today, and I can't wait to get it in. Hopefully I can do it this next week.
 

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the darkside is loud
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Now those are some useful pics.
I had no idea it was more of a gloss black.
Thanks for the gut shots.
Check out how they individually screwed down the heatsink clips instead of one long rail.
I guess Chinese labor is cheaper than I thought.

Bret
PPI-ART COLLECTOR
 

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Nice. A pair of these would be perfect for my up and coming install. They'll fit nicely under my passenger seat:D
 

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"Moving the amp to the Cogent test bench verified my impressions from my listening session, the amp makes gobs of power, and does it with relative ease. Efficiency was excellent, especially at fractional power levels where the majority of us listen, and the P900.4 managed to exceed all its published specs. Frequency response measured ruler flat in the audio band, and extended to over 30kHz. Signal to noise proved to be equally as impressive, scoring -82dBA @ 2V. About the only minor gripe I had was the amp didn’t have quite as much gain as I might have liked, requiring about 280mV of input to drive it to clipping with the gains maxed. This is no problem if you have a high volt output radio, but if your head unit’s preamp output voltage is on the anemic side, high quality recordings with wide dynamic range and lots of crest factor may not be able to get the amp to full power. But any good 4 volt or higher sources will be perfect."


From the PASMAG review. does this mean the gain has to be higher clockwise than normal? I thought that is what someone said.

does anyone know what the voltage output of these 900.4 amps are? I would like to get an idea of wether or not we are close or not on the gains in my buddies truck. or bus out the dimm.


we were also thinking of bridging the amp and turning the gains all the way down to get more use of the entire amp.

when he got it he was going to use all 4 channels but since he installed it we have just run 1-2 .

it seems a waste to use just half an amp.
 

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Just bridge it....headroom is golden:D

yes, this amp does in the neighborhood of 400 x 2 bridged give or take some.

with gain as low as possible it would be what ? 200'sh ? but the amp would use all it outputs to get there versus half when not bridged. does that sound correct?

sounds logical to me. I am just wanting to know ballpark where the gain is needed with a 4 volt input. I am sure its not getting but maybe 2-3 ..(its a jvc deck but its a good one) lol.


running a set of Image Dynamic ctx65 btw
 

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Most mids won't take advantage of more than 100watts RMS. The PPI P900.4 provides over 100watts into 4ohm load, which seems plenty. On the other hand, bridging can reduce SQ. For example, I have observed alternator whine go from virtually inaudible to being fairly audible (with music paused at least) once my amplifiers channels were bridged (different amp brand). Also, in bridged mode, the amplifier runs less efficiently, drawing more current and producing more heat (ok, this may be insignificant if you just drive a couple of speakers) Just leave it as is for now IMO.

400watts RMS is more than enough to drive 90% of subwoofers. Most mids can not take more than 100watts in terms of excursion limits, if you decide to drive them hard. The crossover boxes also have limits with regards to how much power you can use.

Regarding setting the gains, my rule of thumb for amplifier gains is that they need to be high enough so that when I listen music at normal sound level, the position of the stereo's volume knob is at 75%. If the amplifier is so weak that you run out of gain with that setting (this can't be a problem with this PPI), then get a better amplifier or bridge channels.
 

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yes, this amp does in the neighborhood of 400 x 2 bridged give or take some.

with gain as low as possible it would be what ? 200'sh ? but the amp would use all it outputs to get there versus half when not bridged. does that sound correct?

sounds logical to me. I am just wanting to know ballpark where the gain is needed with a 4 volt input. I am sure its not getting but maybe 2-3 ..(its a jvc deck but its a good one) lol.


running a set of Image Dynamic ctx65 btw
If your stereo/source has a high voltage output, I don't think you need to worry about the pasmag comment.
 

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Most mids won't take advantage of more than 100watts RMS. The PPI P900.4 provides over 100watts into 4ohm load, which seems plenty. On the other hand, bridging can reduce SQ. For example, I have observed alternator whine go from virtually inaudible to being fairly audible (with music paused at least) once my amplifiers channels were bridged (different amp brand). Also, in bridged mode, the amplifier runs less efficiently, drawing more current and producing more heat (ok, this may be insignificant if you just drive a couple of speakers) Just leave it as is for now IMO.

400watts RMS is more than enough to drive 90% of subwoofers. Most mids can not take more than 100watts in terms of excursion limits, if you decide to drive them hard. The crossover boxes also have limits with regards to how much power you can use.

Regarding setting the gains, my rule of thumb for amplifier gains is that they need to be high enough so that when I listen music at normal sound level, the position of the stereo's volume knob is at 75%. If the amplifier is so weak that you run out of gain with that setting (this can't be a problem with this PPI), then get a better amplifier or bridge channels.

I know how to set gains but all amps are not the same and when it was stated gains had to be set rather high I had to ask.


as for the power output. if the gain is set to minimum- all the way counterclockwise- then we are not going to get near 400 watts rms.

what I would think would happen is all the outputs would be combines to get the watts instead of half.

the gain would limit the amp from producing the full power output.
 

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I am just wanting to know ballpark where the gain is needed with a 4 volt input. I am sure its not getting but maybe 2-3 ..(its a jvc deck but its a good one) lol.
I installed my P900.4 today and did a quick gain setup by ear. The gain pots have no reference marks. If that matters to you you'll have to make your own marks. I had music playing, not test tones, so I'll need to recheck the gains.
 

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I know how to set gains but all amps are not the same and when it was stated gains had to be set rather high I had to ask.
How do you know that gains are "too high"? If the amplifier has 6V max input sensitivity at the minimum gain position, then I can see the middle and even way past the middle gain position being appropriate for a head unit with 4V output. Specially, if you're calibrating so that you never use head unit's volume knob at full tilt. This means the amplifier probably will never see input voltage above 3V.
 

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How do you know that gains are "too high"? If the amplifier has 6V max input sensitivity at the minimum gain position, then I can see the middle and even way past the middle gain position being appropriate for a head unit with 4V output. Specially, if you're calibrating so that you never use head unit's volume knob at full tilt. This means the amplifier probably will never see input voltage above 3V.

most people do not put the gains at 3/4 max or so. most people never have it past 1/2

What is full tilt on volume knob? is that 3/4 volume or is 13/16 full tilt?


does anyone know the voltage output on these so I could set it with a meter?
 

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I installed my P900.4 today and did a quick gain setup by ear. The gain pots have no reference marks. If that matters to you you'll have to make your own marks. I had music playing, not test tones, so I'll need to recheck the gains.

on his amp it has little arrows at one spot. the marker I guess. but mine were in the wrong spot so i ignored them. not a great sign on such an easy detail.
 

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yes, this amp does in the neighborhood of 400 x 2 bridged give or take some. with gain as low as possible it would be what ? 200'sh ?


The gain control does not change how much power an amp makes. It only changes how much input Voltage it needs to make it. With the gain all the way down you need more input VOltage to make full power. As you turn the gain control more and more clockwise you need less and less input VOltage to make full power. The only time you'll ever not make full power is if your HU doesn't have enough output Voltage.
 

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does anyone know the voltage output on these so I could set it with a meter?
That will depend on how much power you're trying to get out of it. The output Voltage will be different at 50 Watts vs. 150 Watts. Then it's basic math. Square the measured Voltage and divide by the Resistance of the driver and you'll have the output in Watts.
 

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I got mine installed yesterday. Writing a separate review given this and pasmag review would be quite redundant. Based on everything we know so far, it performs within manufacturer specifications, runs efficiently, and takes little space. Sonicelectronix has these on sale for $200, but even at 'normal' $230 price, these are a good value. Another thing I like about this amplifier is that you can turn off the filters completely. I prefer to set crossover between my speakers and subwoofer on my stereo, which should result in more precise settings and also in less phase shift issues.


Right now, it's running only a subwoofer with bridged channels. The subwoofer is Infinity Kappa 120.9w. I have set my gains by ear as usual. My head unit has 4V outs. The amplifier gain knob is a little below the middle position. The texture of bass sound _seems_ to become more robust, somewhat more detailed. However, it's not a fair comparison vs my old amplifier, since my previous sub amp was a cheap A/B amplifier that probably wouldn't even provide its rated 250watts. Moreover, I flipped the impedance switch on my subwoofer from 2ohm to 4ohms which should result in all three voice coils now wired in series. This later change could also affect the sound somewhat. Overall I am pretty happy. Right now I am looking for a good way to mount this amplifier on the back of my subwoofer box.

I see only a few minor negative issues so far:

1. 4 AWG wire barely fits.
2. Accessing screws for power, speakers, etc is a little uncomfortable. Those bars on sides get on the way.
3. The manual does not explain how to bridge channels. I had to infer this from the instructions for the 2-channel version and also from the manual of Polk D4000.4 (a closely related amplifier).
 
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