longhornsk57

I am looking an amp that is smallish and can power 4x 135 at 2.5 ohms. Was looking at possibly this one but wanted some other options around the same price.

HushCarAudio

It's a decent amp but discontinued. Take a look into Skar Audio SK-M4004D. It will do what you want, is smaller, cheaper, and readily available. I can ship one out to you quickly too.

nineball

arc audio x2 450.4. it will do 125 x 4 @ 2ohm. it is a class d so it is efficient but it is one of the best sounding line of class d amps on the market. it's tiny too - 8.173"(L) x 6.268 "(W) x 2.086"(H). you will be quite happy with it!

https://www.arcaudio.com/store?p=179595

whatever you decide make sure you check with the manufacturer before making any purchases to ensure the retailer is an authorized dealer for that line. no authorization = huge potential for problems down the line. large sites like sonic electronix and woofers, etc sell lots of things they are not authorized dealers for, same thing with mom and pop shops. doing your due diligence before making a purchase is the best first step to take. for example neither amazon nor any of the amazon vendors for that amp are authorized pioneer dealers, so if you bought the amp and something went wrong you are screwed and at their mercy.

HushCarAudio

I wanted to follow up and say that the unit I suggested is smaller than most I've seen in the market, a class D, roughly 60%+ cheaper than most comparable amps, sounds awesome (I run it in my truck), reliable, blah blah blah. It's a dope amp period and that's coming from my personal experience.

longhornsk57

what does it do at 2.5ohms x 4?

dhmcfadin

1. What speakers are you tuning that are 2.5 ohm
2. At 2.5 ohms, you generally have more power output. As resistance decreases, power increases but with more power comes more heat.

longhornsk57

Infinity kappa 90CSX for the fronts, and some kappa 6.5" for the back. I just want to fully power the speakers, so I am trying for at least 135W x 4 at 2.5 for the fronts, probably need like 90W or whatever 6.5s I am going to get for the back two channels.

dhmcfadin

Thanks for that info.

So remember that amplifier output is linear. Just because an amp says it can put out 125 watts at 4 ohm, does not mean it will put out 125 watts at 1/4 or 1/2 volume. That's just the nature of amplifiers so don't get stuck on the power output. Efficiency and low noise are more important.

Next, power isn't everything. Speaker design and speaker installation/sound treatment are significantly more important than sheer power. By feeding a speaker with a 135 watt rms only 75 watts, you in no way limiting the speaker in output or performance. Generally the rule of thump is that double the power equals about 1 dB in volume increase. 1 dB is nothing unless you are competing in an SPL competition.

Finally, higher frequencies require less power to play at the same volume as lower frequencies. For example, a tweeter at max volume will generally receive a maximum of 5 watts. 5 watts.

The point is, you could feed those speakers 75 watts and they would sound absolutely incredible. They would be louder than one could comfortably listen for an extended period of time. Power is not everything.

longhornsk57

The problem I am running into is that I keep getting different opinions from different people, and there's a million amp choices out there, and I feel like I have to do hours and hours and hours of research just to buy an amp. All I really need is a small amp that is not too expensive and will put out enough power so the speakers sound loud and clean.

nineball

if you stick to the major brand names (alpine, pioneer, jbl, etc) you will be fine. look for anything in the 100-150 RMS @ 2ohm range and you will be golden.

since you like pioneer (based upon your first post) maybe https://www.crutchfield.com/p_130GMD...-GM-DX874.html or maybe this jbl model https://www.crutchfield.com/p_109GTR...L-GTR-104.html . you could also just browse them yourself and find one that suits your needs and budget - https://www.crutchfield.com/g_347050...pe|FF4@Channel It shouldn't be more than 15 mins at best to look them over, and if you have any questions you can always call crutchfield or ask us here. no one can touch their customer service and they are authorized to sell everything they sell!