MB quart REF1.800 clamped

[AStovall 10+ year member]

I got this amp off ebay for $112 shipped

the amp is rated at 300 @ 4 ohms with 14v 650 @ 2 ohms @14v and 800 @ 1 ohm a 14v.

This was done in a 06 cobalt with no electrical upgrades ,note the battery's factory location is in the trunk. voltage was noted at 14.3v with the car idling. voltage dropped to 13.7-13.4 during burps. The gain on the amp was set to max. volume was adjusted at the deck until clipping was observed at the amplifiers output.

voltage at idle. Ignore the amp meter.

voltage at speaker terms at the amp 34.6v the load was 2 MTX 4500's wired to 2 ohm.

At 40Hz .

34.6 x 13.1 =453.7 watts RMS @ 2.641 ohms

(If you take 34.6v and put it into an even 2ohm load the math comes out to 598 watts. )

I tried this at 1 Ohm using resistors. I also did this with the car off and at 48hz the amp started to make an audible hiss from the chassis as the signal began to clip so i stopped i may try again at a lower freq with the car running i didn't have time play with the setup today(lunch break ended)

22.8v x 25.1A = 572 watts rms @.908 ohms... i think this may be due to the voltage drop with the car not running, that or the amp just cant do rated power at 1 ohm.

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[AStovall 10+ year member]

Id also like to note im using a line level converter , my next task is to see if that noise is due to my setup of produced by the amp.

 

[skylineTT 10+ year member]

I feel like that amp should do more power than that.

 

[MANTI5 10+ year member]

Yeah, most tests I've seen with MBs have done more than rated.

 

[AStovall 10+ year member]

Yeah... I'll take a look at the input sig Tomorrow. Keep inmind that this amp is imbetween entry level and the onyx. Im curious as to why noise is only present onthe top half of the sinewave

 

[AStovall 10+ year member]

Ok so i went back out checked my source, and its surprisingly clean. so i checked the ground for the amp. cleaned the contact patch and re torqued the ground and the noise seems to have gone away.

I was able to get 643w @ 2.66 ohms(42Hz) (corrected to 861wrms @ 2 ohms,which would be mean the amp is under rated. but as you can i had to drive the amp into clipping to achieve this. so that corrected number is a little misleading .

492 watts @ 2.77 ohms(43 Hz) (corrected to 684wrms @ 2 ohms)

553wrms @ 2.46 ohms (43Hz) (corrected to 680 wrms @ 2ohms) not sure what caused the impedance shift ,maybe heat?)

 

[CAT MAN 5,000+ posts]

not bad for a ref series amp

 

[zako 10+ year member]

The discontinued REF series full range amps were also very nice. A Russian magazine tested REF4.80 for 4x110watts RMS at 4ohms and 4x180watts at 2ohms with 14.4V battery at 1%THD (the rating is 4x80watts RMS at 4ohms). I picked one up for $120 shipped. It's a very nice and compact Class A/B amplifier. It could rival class D amps in size and power.

They also tested that the newer FX series MB Quart amps. In short, it seems like they're crap. The 2-channel full range model provides maybe 60% of the rated power.

 

[PPI_GUY 10+ year member]

The discontinued REF series full range amps were also very nice. A Russian magazine tested REF4.80 for 4x110watts RMS at 4ohms and 4x180watts at 2ohms with 14.4V battery at 1%THD (the rating is 4x80watts RMS at 4ohms). I picked one up for $120 shipped. It's a very nice and compact Class A/B amplifier. It could rival class D amps in size and power.
They also tested that the newer FX series MB Quart amps. In short, it seems like they're crap. The 2-channel full range model provides maybe 60% of the rated power.

If you don't mind me asking, where did you pickup the REF4.80? Been looking for one and $120 is a fair enough price.

On the FX series; they claim to be CEA compliant so, I guess that really does mean nothing!

 

[zako 10+ year member]

If you don't mind me asking, where did you pickup the REF4.80? Been looking for one and $120 is a fair enough price.

Unfortunately, they got discontinued so it's pretty hard to find them now. If you google for it, sometimes an odd vendor has them, but not always this cheap. I got mine from dpcauto.com. It looks like they don't have the REF4.80 any more. However, they still have the weaker REF4.50 for $72.50 plus shipping. I assume, by translation, that REF4.50 is also somewhat underrated, maybe by 20-30%. Given the size and its specs, it's still a good value. If that's not enough power, you could buy something like MB Quart ONX4.125. However, the REF4 was about half of its size.

In my view, a lot of the newer MB Quart amps are not what they used to be. My preference for the "budget" amplifiers is now PPI. Their Phantom, Power Class, Sedona, and Black Ice are all excellent amplifiers for their respective class. I know that based on tests the first three do their rated power with the Power Class being the cleanest, highest end amp in the line. Black Ice is relatively new, so there is no test data or user feedback on it yet. It is about to hit vendors in a few weeks. It's supposedly based on a decent existing Soundstream board/design, so it's expected to be a good amp line too.