QuestionI have two 12" subs in my car and want to get a new amp. I'm looking at a 1500 watt, 750rms mono amp made by Bass Inferno. I havn't heard of this brand before and would like to see what you think. Are they a reliable brand? They want about $120 for the amp. Is this a good price? Thank you.
AnswerHi Eric,
I hadn't heard of Bass Inferno before, so I checked out their web site. One thing I noticed is that they don't provide very much information at all regarding their amplifiers' power specs. The particular amp that I think you're looking at is rated 750 watts at 4 ohms, 1500 watts at 2 ohms--but the term "RMS" does not appear in the power rating (although some of the online vendors that offer this amplifier list it as a 750-watt RMS amp).
I'm extremely skeptical of the 750-watt rating--I think it's a "peak" rating, and a highly inflated one at that. If you want the technical assessment, read on; if you want the summary, skip down to the last paragraph.
I don't have much to go on except the picture, but it appears that the amplifier uses two 15-amp blade fuses. Here's the issue: every bit of power that an amplifier produces must be drawn from the vehicle's charging system. An amplifier doesn't create power from thin air; it draws current from the battery and alternator and converts it to audio output power. Because no amplifier is 100% efficient, much of the power drawn from the vehicle is wasted as heat, instead of being sent to the speakers. The Bass Inferno amplifiers are specifically listed as "Class AB" amps. This is a less efficient design than the other major type of amplifier, Class D. That means that for every 100 watts of power drawn from the vehicle's charging system, only about 60 watts or less is sent to the speakers. So if this amplifier is going to produce 750 watts RMS, it needs to be able to pull about 1250 watts from the charging system.
That's where the fuses come in. Because the amplifier uses two 15-amp fuses, it can't continuously draw more than 30 amperes of current from the battery and alternator. Bass Inferno says that the power rating is based on an input voltage of 14.4 volts. There's a very simple formula for power consumption when you know the voltage and the current: Power = voltage x current. Multiply 30 amperes by 14.4 volts and you get a power consumption of 432 watts. That's the maximum power level that the amplifier can draw from the vehicle; and because it's only about 60% efficient, a maximum of 260 watts could be sent to the speakers. It's simply not physically possible for the amplifier to produce more power than this, given the 30-amp limitation on its power supply. In fact, most manufacturers will design an amplifier with larger fuses than it really needs; so it's very likely that the real power output is actually quite a bit lower.
To sum up, there's simply no way this amplifier could produce 750 watts RMS for any length of time. So we have a low-priced amplifier that's marketed with a clearly inflated power rating, and no published "RMS" rating to be found, even on the manufacturer's web site. My best guess would be that this is about a 150-watt RMS amplifier. If you're looking for an amp that can produce 750 watts RMS, or anything close to it, I'd definitely pass on this one.
Hope this helps!
Brian
