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Punch amp setup question


Mitchmoeller

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Just bought a 2008 247 and learning about amps and stereos. I need some help "tuning" my sound system.

I have 3 amps

Punch 400-2

Punch 400-4

Punch 500-2

My setup:

The 400-2 is connector to a subwoofer under drivers feet

The 500-2 is connected to 2 tower speakers

The 400-4 is connected to 8 interior speakers. The "front" side is connected to 2 bow cockpit speakers and 2 speakers in the dash (these are the stock speakers that came in the '08). The "rear" side of this amp is connected to the 4 speakers in the rear lounge. 2 on the sides and 2 in the back. These 4 speakers were upgraded to Rockford fosgate speakers just before I bought it

My problem:

The first time I had it on the water,the system initially sounded great. When my kids started to really crank the volume, at one point I started getting all sorts of distortion. It only happened at high volume and certain songs. Went away when the volume came back down or when the song switched. Last weekend I was trying to diagnose the problem (I thought I had some blown speakers).

What I discovered so far is that the two tower speakers sounded great no matter what volume or music I pushed through them. The sub sounds fine as well. The four "front" speakers which were the stock '08 speakers also sounded great throughout the volume range (no noticeable distortion). The 4 newer Rockford fosgate speakers in the rear sounded great up to a volume level but all distorted like crazy at about the same volume level. I am guessing that means I don't have 4 blown speakers but some other problem. Last night I checked out the settings on the 400-4. The front speakers are set for high pass only which I think means that the amp doesn't try and push lower frequencies through the front speakers. The 4 rear fosgates are set for all-pass which I think means they get the full spectrum of frequencies pushing through them.

The boat was sitting in my driveway so I couldn't really debug the high volume distortion problem without annoying the entire neighborhood. Tonight I will take it somewhere where I can fully run thorough the range.

Sorry for the long post but I wanted to be clear on my setup. My question is where do I start the troubleshooting to eliminate the distortion in my 4 fosgate rear speakers? Can they handle all-pass on frequencies or should I go to high pass? If I leave it on all-pass does that mean the crossover adjustment doesn't really do anything? Should I start with cross over or play around with gain first? Not really sure where to start there. Any suggestions would be appreciated. I am not really a stereo guy but reasonable at troubleshooting.

Thanks

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You've answered your own question for the most part. The "rear" chnls driving the 4 main cabin speakers most definitely needs to be set to hi-pass. The Hz dial then set to about the 100hz range. This will go along way in alleviating the distortion. The gain level for that rear half can also contribute to the distortion if its too high. If its higher then front gain dial, turn it down to mirror the front setting. Next up is the level at which a typical head-unit can be played at. We suggest keeping it below 85% of max. Finally, music quality. This can change dramatically from one song to a next.

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Another question on my system is a couple of times when the volume was set pretty high the entire system dropped out for a few seconds. I am assuming this was an amp overload thing. Am I asking too much of the 400-4 amp to power 8 speakers or is that pretty standard?

Thanks

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If the ENTIRE system dropped out then the issue is definitely not exclusive to the one amplifier.

Verify that this event is not the last amplifier going into protection (and noticed until then) rather than all amplifiers simultaniously.

When the entire system drops out at the same time the cause is common to all amplifiers. It is unlikely that low voltage protection or shut-down would occur on all amplifiers at the identical moment given the varying loads and current draws.

However, if the voltage dropped below the source unit shut-down threshold and the source unit shut-down threshold was at a higher voltage, then when the source unit shut down it would remove the remote turn-on voltage from all amplifiers at the same moment. So when the system shuts down verify whether or not the source unit is part of the event. And the moment that the system powers back up measure the voltage supply while under load.

David

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Thanks David

I will check this out. I think when it dropped out it was the cabin speakers but not the tower or the sub. At the time I was unaware how the amps were separated so I didn't know how to analyze it. I just remember it being muted but not going totally silent. It was hard to isolate because it only happened for a few seconds at a time and I was driving the boat pulling a wakesurfer so had a lot going on

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Thanks David

I will check this out. I think when it dropped out it was the cabin speakers but not the tower or the sub. At the time I was unaware how the amps were separated so I didn't know how to analyze it. I just remember it being muted but not going totally silent. It was hard to isolate because it only happened for a few seconds at a time and I was driving the boat pulling a wakesurfer so had a lot going on

Well, that definitely makes a difference if it was just the one amplifier. And that would lead you to believe it is a thermal related issue.

There's nothing wrong with a 2-ohm load on most amplifiers. But a 2-ohm load on ALL channels of a given amplifier can really tax the amp's power supply which is a limited power resource. Having everything highpassed, thereby natrrowing the bandwidth, definitely will help the load. That change alone may be enough of a difference. Or, if after that change you still have the issue, you can add another 4-channel amplifier to change the distribution and lighten the load.

Keep in mind that low voltage does compound thermal issues. So make sure you have adequate supply cables too.

David

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