S4EQ 4 Band Pre Amp Car Equalizer with Gold Plated Front Rear and Subwoofer Outputs

...you plan to use the subwoofer output. That is the only real issue with this unit. The sub output level is very low especially compared to the full range output, and the frequency adjustment doesn't really work correctly. If you plan to use the full range outputs only, this does the job very well especially for the price! Output has a small amount of hiss (almost inaudible). It has a solid amount of gain to drive the outputs. Internally it has a +-15 volt power supply to drive its op amps, and power supply ground is isolated from the I/O ground. Sound quality is quite good. You will spend a LOT more to get anything better. And to those that complained about "terrible" sound quality: the phase switch on mine was set to 180 degrees new out of the box, this is NOT the correct way on a properly installed system. Start with 0 degrees, then if you aren't happy TRY the 180 and compare. I bet most systems will sound worse with the 180 setting.

Works fine BUT- I had same problem as others. One of the RCA plugs broke loose inside when I installed my cables, messing up the master volume. I've got the cables zip-tied at the rear which keeps the circuit board from shorting out. The RCA cables I used fit very tightly and were difficult to install. From now on when I install cables (to any unit) I will install them onto another device first, like an old CD player to make sure they are not too tight. You shouldn't have to use so much force that it breaks the unit you are installing them on. I don't think it was the fault of the EQ here. Everything about the unit seems to be of very good quality and the EQs performance is great. Clean and clear sound, and the preamp voltage rise really cranks up my amplifier's output. I really like this EQs variable sub frequency control. It allows you to change the crossover frequency right from the dash instead of resetting the amp. Works awesome-I can optimize hz values for different music on the fly. It makes a huge difference in dialing in the perfect sound, song to song. The rest of of this EQs performance is very good too. Master volume, sub volume and f/r fader-all good. The four band EQ boost/cut +/-18db provides a definitely noticeable difference when you dial the controls. Overall a very good unit. Would purchase again. The variable sub frequency control really gets it done-5 stars. Update Review 2-25-15 Purchased another S4EQ for another vehicle. Pre-installed my cables onto the old head unit before using them on the new EQ. No problems. Using the EQ on a sub only signal from my head unit then to an amp. EQ door speakers with a seven band Clarion. Works great. Love controlling volumes AND sub frequency (S4EQ) using three easy to reach dials. No having to read displays while I'm driving. SSL S4EQ-Spot on. Perfect for a great price. Would definitely use again.

Equipo bien ensamblado, buen acabado y por si fuera poco un excelente sonido y gran desempeño. Pocos como este equipo, precio mas que justo. Si usted es un aficionado al buen sonido este es su complemento exacto para mejorar su equipo de audio.

Nice graphic EQ. Work as planned. LED defaults to Red light, Green is the only other option. Comes with mounting hardware. Decent quality for the price.

Básico pero muy buena calidad de audio entregada. Distorsiona si la ganancia está muy alta Aún con los amplificadores y los subwoofer conectados como se debe. Ya probé varias fallas posibles y nada pero sin funciona bien a una ganancia media alta