Input voltage question

Grim0013 · Post by **Grim0013** » Sun Dec 21, 2008 3:57 am

OK, this just seems....weird to ask. I've been out of the audio game for awhile and was never exactly a pro to begin with, so 'ere we go... I have an Octane limited edition, and I am considering using the front half to run some ID horns, but am worried that it may simply be too damn much power. The relevant stats are:

Source
Output Voltage: 5V (From an Auzen X-Fi Prelude)

Amplifier
Input Voltage: .2 - 6V
Output Power: 100W @ 4 Ohms

Ok, so that may seem all fine, but for the fact that the amp makes about twice as much power as I am looking to send to the horns. They are 8 ohm horns, so we're talking 50W each from the Octane......unfortunately, I only want to send about 20W to each horn, lest their 110db sens overpower the rest of the system. (4x6.5", 90db sens, about 100W each from the other half of the Octane running at 2 ohms. 2x15", 91db sens, about 350W each from a MS-2125 at 2 ohms bridged.) So, what I am worried about is if even with the gain minimized, will I still have too much power on the horns?

I guess I can always wait until install time and find out that way, but then I would need to wait another who-knows-how-long until I was able to get my hands on a MS-275 to swap the horns over to. At which point I may as well pick up another 2125 and swap the mid-bass over to that so I can go with an all MS series look. Hrmmmmm, always some fly in the ointment, eh?

Thanks

joyride · Post by **joyride** » Sun Dec 21, 2008 7:05 am

I wouldnt be concerned about it right now. I had a set of ID horns (CD1 pro's) that were ran off the front of a ZX450 (with a PLD in front of that). PG amps are made to accept up to an 8v input, so you should have more than enough room to cut down the power with the sensitivity knob. Or, at least you should try it first. I truly dont think you will have a problem. what are you going to use for midbass anyway?

Post by **smgreen20** » Sun Dec 21, 2008 7:09 am

Set the gains on everything else first, then set the gain for the ID horns last to blend.

thedeal7235 · Post by **thedeal7235** » Sun Dec 21, 2008 7:27 am

what smgreen said

Grim0013 · Post by **Grim0013** » Sun Dec 21, 2008 9:32 am

smgreen20 wrote:Set the gains on everything else first, then set the gain for the ID horns last to blend.

That's the plan.....just a little worried that I may end up not being able to get them to blend with that much amp behind them.

joyride wrote:I wouldnt be concerned about it right now. I had a set of ID horns (CD1 pro's) that were ran off the front of a ZX450 (with a PLD in front of that). PG amps are made to accept up to an 8v input, so you should have more than enough room to cut down the power with the sensitivity knob. Or, at least you should try it first. I truly dont think you will have a problem. what are you going to use for midbass anyway?

Mid-bass is two pair of ID 6.5". They're OEM for marine applications and are nearly identical to their CX64. Here's the thread over on DIYMA.COM. Dude's got them for $90 per pair shipped. By all accounts one hell of a deal. Everyone who's picked them up so far sounds positively pleased with them, particularly as a dedicated mid-bass with 100-150W each. The subs are Acoustic Elegance IB15s.

My original plan for powering this setup was 2xMS2125 and 1xMS275. I have the Octane, and it is a PG limited edition, so I was kind of trying to make it work. But, it still isn't the Frank I wish I still had. On top of that I suspect I would be better off with another 2125 for the mids and a 275 for the highs, as originally planned though.

The guy I've been talking to at ID suggested 50W to the horns, 500W of mid-bass and 700+W sub-bass. I've got the subs covered with the 2125, but the Octane comes up a little short on the mid-bass and a little long on the horns.

Post by **stipud** » Sun Dec 21, 2008 9:45 am

If you've got a system voltage of 8 volts, with gains minimized you will get 50w
At 4 volts, you will get 25w with gains minimized
At 2 volts, you will get 12w

So as long as you have 4v RMS or less, you will be able to reach the desired power level.

However, the rule of thumb is that every time you double the power, you gain 3 decibels of output. So from 25-50w, you're only adding 3dB. That should be easy to make up elsewhere. For example, running two midbasses will add 3dB as well, on the same power. And 6dB if you double the power. So not as big of a deal as you may think