NDSP Quad Cortex

[Classic07]

I like the PLX series of amplifiers from QSC for several reasons:

There are a ton of them available on the used market for reasonable prices.

Many of them were used for house sound systems in a church or club and they were installed in one location for their entire service life, so it is easy to find them in like new condition.

They are fairly lightweight (about 20 lbs) designs using switched-mode power supplies coupled to class A/B, class G, or class H amplifiers.

Unlike many of power amplifiers marketed toward guitar players, even the lower wattage models have sufficient power properly drive a stereo pair of 16 Ohm cabinets.

QSC is a well established brand and pro audio service centers can diagnose / repair them if needed.

While I had the house to myself for a few hours yesterday I played an Axe-FX III into a QSC PLX 3402 and a pair of 4x12 cabinets. With the power amp on the lowest gain setting there was enough volume to feel every note in my gut. That was some good clean fun.

The specs appear to only mention 4 and 8 ohms. Will the drive 16 Ohms at proper volumes?

 

[Dez]

The specs appear to only mention 4 and 8 ohms. Will the drive 16 Ohms at proper volumes?

You can drive a 16ohm cab with an 8ohm amp.

 

[paisleywookiee]

You can drive a 16ohm cab with an 8ohm amp.

Yeah, but it puts up a fight. A bit of resistance, you could say.

 

[Dez]

Yeah, but it puts up a fight. A bit of resistance, you could say.

 

[OrganicZed]

You can drive a 16ohm cab with an 8ohm amp.

Yes. Solid state amplifiers are safe to use with higher impedance loads than those specified. It is inadvisable to run a load with lower than the prescribed minimum load (for example, less than 2 Ohms). There is no problem driving a 16 Ohm load but be aware that the total output wattage will be approximately half that of the rated output wattage at 8 Ohms. For example, the PLX 3402 that I use is rated for 700W per channel continuous output with both channels driven at 8 Ohms. It likely puts out about 350W per channel stereo into 16 Ohms. That is more than enough to drive a pair of 16 Ohm 4x12 guitar cabinets.