wanted to see what you guys thought about this b/c I hit 3 local shops today and each one had advice that was no one near the others! I'm using a Diamond Audio S600s component kit up front. Its a 4Ohm set and Diamond lists them at 170W. They are a pretty efficient set, 91dB on the sensitivity.

I'm most likely going to go with PPI amps all around. At 4ohm I pretty much have two options from their current line. 125x2 or 200x2 @ 4Ohms. Do I go with a lower output and increase the gain until I'm happy? Or do I go with the higher output and decrease the gain until happy?

I've got mixed answers all morning so would like to see what you guys are thinking?

 

i don't know the exact answer....but i would say go with the higher and turn down. if you are ever going to upgrade the speakers...you'll have the extra power. i might be totally off....but that's my opinion.

 

Hard to say. Do you know offhand what voltage the PPI amps are measured at? If it's at 14.4v, then they are overrating them and the 200w would be your best bet because realistically, the amp is probably never going to get 14.4v. If it's low, like in the 12-13v range, then the 125w amp would be a better choice because it's underrated.

There will not be a noticeable difference between the two, especially with a 91dB sensitivity. Remember that the sensitivity rating is tested at 1 watt input power, 1 meter away from the speaker. It is only a measure of how loud they are at low power. Give any speaker the power it needs and it will play loud.

Plus, it's safer, you don't have to worry about overdriving the speakers and blowing them, and you don't have to worry about overheating the voice coil.

I would save the cash and get the 125w one.

 

i would go with the higher wattage . the 170w listing is basic and also the listing on the amp is a basic listing as well . the way i understand it is that wattage changes do to frequency . besides if it starts to destort then you turn it down anyway. i would not be conserned with a 30 watt difference between the amp and speakers.

 

Both amps are from PPI's "PCX" line. They have PWM (Pulse Width Modulated) Adaptive Power Supply. So if its getting 12 or up to 14.4 the output is going to be the same.

 

Your speakers are safer w/ an amp over their rated power than with an amp that's under.
Seems odd, but it's due to clipping of the waveform. This happens when amp is called on to provide more power than it can provide. If you look at a pure tone it is a nice sine wave; when it clips the top and bottom are clipped off the waves. This creates a LARGE high frequency signal that'll pop your tweeters.

I'd go with the 200W amp. If you go with the 125W amp, see if it has a clipping protection circuit.

Here's some links to more in depth info:

http://www.jblpro.com/pub/technote/lowpower.pdf
http://www.abrown.com/power.htm

 

Go with the 125 W amp, that is WAY more than enough power (especially with a good amp) to push a fairly efficent speaker. Hey, more is aways better, you can never really overpower a speaker, the speaker will start to disort first (that is your STOP sign), but 125 watts is a lot of power. You will go deaf if you used all 170 W the speakers are rated at.

Like I stated before I ran a set of speakers off a good 30 watt per channel amp, and could hit 130db (actually 128, or so), and that is LOUD (the speakers were horns and were super efficent, close to 100db). See if the shop has both, listen, and see what you think. And remember the speakers are going to be closer to your ears, and in a much smaller area.

I always tried to use as little power as possible, for less current draw, and to stay in lower power classes (although that does not matter in your case).

I just think the 200 W amp is overkill, I think a 50-75 watt amp is plenty for a good sound.

 

Sorry to post again, but I figured if I was going to run my mouth, I would look into those specific speakers. So, I went to Diamond's website and looked at the specs, and downloaded the .pdf manual. They seem to be just like the Diamond's I used 8 years ago (or very similar). First off, let me say great choice, super flat response, and a silk dome tweeter (which to me makes all the difference it the world). You will not need an EQ, or anything, that is why I loved the Diamond's more than anything in their price range (although I like Dynaudio also).

125 watts will be plenty, the 170 watt rating is the MAX power rating (peak), RMS (constant) is much lower. Chances are the amp puts out more than 125 watts, especially if it is rated at 12V and you can usually get 14+ to it (use a cap.).

Another nice feature is they have a "rear fill" output on the cross-over that attenuates the signal by -10db. You will loose the fader, but if you do run rears (something like a decent coax), this will help, and possibly simplify the setup.

I am by no means a expert, to be honest I have not had a system in my car for 3+ years (that is all I did for 5 years, then i really got into Home Theater, and now performance of cars), and competed in car audio in 5+ years, but I do not think much has changed, I welcome others input on this.

 

Thanks gusy so far! Anyone else have comments this? Speaker is 170W peak....give it 200W and turn down gain? give it 125W and turn up gain?