Dammit, you guys were right!

unrealii

If anyone remembers this long thread a while ago:
http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=18943&perpage=30&pagenumber=1

I originially ran the fronts off the high and the rears off the low. Finally yesterday I decided to just run the fronts and biamp them. You guys were right, it sounds far better.

Guess it could have been since the cut off for the HI signal going to the fronts was 200Hz, so I wasn't getting the full range out of my 6.5"s in my doors.

Only downsides to this was that it took me 3 hours to get to the amp since the entire back seat has to come out to unbolt it. Now I put terminal blocks so that if I want to re-wire it in the future, the amp doesn't have to come out. Also, I ended up messing up part of my interior near the panels I had to pull off because my hands were dirty and I didn't see that because it was dark Oh well, time to detail the car

MacLeod

Another shown the way of truth and light.

I was the same way til I decided to bi-amp my front speakers and dump the rears altogether. It made a huge difference and Ive been a strong advocate of front stage only and bi-amping ever since.

Systems

I'm using a JBL GTO 4000 to power my JBL GTO6506C's up front and a Polk GNX104. I'm planning to opgrade to a pair of MM124's in the near future, using a Rockford Punch amp to power them.

If I bi-amp the amp, it puts out 150w x 2 rms, but the components are rated at 70w rms. Two of my friends offered two solutions. first, good speakers normally handle twice their rms ratings, and so I can do this and keep the gain at 50%.the other one advised me to keep it at 25%.

Are any of these safe?also, wouldn't that much power drown out the sub, because right now, unless the bass boost on my HU is turned on, the bass is a little hard to hear when the car is moving...or will the my planned upgrade compensate for that?

neomagus00

going from a single gnx to a pair of mm's is a big upgrade - you're going from one 10" bottom-line to two 12" top-line subs...

on the gains: there's no set way to do this; you can't say "well, i have a 150 watt amp and my speakers take 150 watts, so i'll put the gain at full"... that'll destroy your speakers. there is a good way to do it that prevents your speakers from dying, even if your amp is way too powerful for them, or even if it's not powerful enough. go here. that's a walkthrough for the procedure. it will get you the most sound possible and will let you keep your speakers for a long time.

unrealii

For the past few weeks I have noticed that my highs are magically becoming higher. Almost to the point where they are too loud, but only at the end of the spectrum.

Now this morning, they were getting really high. I tried to see if I could determine what freq this was at, so I started raising the low pass on my crossover from my hu from 4.5khz to 8khz. All of a sudden I started getting a loud high pitched whine. Turned off radio and went to go take my final exam. Came by afterwards, all I get now is a loud whine. Volume on hu is set at 0. I even unplugged the rca inputs from my amp and I still got the loud whine. I tried it again with the engine off and same result.

Can anyone think of any other tests I can do. Once my finals are up (after tomorrow) I'm goign to check the 3 25A fuses on the amp. But other than that, if the amp is indeed bad, I need to take it out and prove to goodguys that it is busted and let them fix it under my extended warranty.

Thanks in advance for any suggestions, comments, or tips.

MacLeod

Unplugging the RCA's eliminated the h/u as the culprit.

If all youre getting is a whine and no other frequencies then its got to be the amp as 2 mids and 2 tweets dont all usually fail at the same time.

A quick double check would be run some speaker wire from the h/u speaker leads to one of the mids or tweet and see if you get music.

I think its probably a wire shorting out to ground. Double check your power and ground wire from stem to stern. If one of them has stripped somewhere and shorting out on a piece of metal this will stop all music and play a horrible screaming thru your speakers.

A test you could do rather than pulling up all your power wires would be run to Radio Shack and grab a bunch of cheap 10 or 12 guage power wire (usually get 50 feet for like $15 or so) and just run a quick wire from the amp to the battery and then from ground to the chassis. If it starts working then youve determined the cause.

unrealii

Thanks for the suggestions.

hmmm...turned on the radio today and everything works...Dont know what to do...

talked to goodguys and they said that they just ship it out to the mtx repair shop in az. Guess I'll double check everything...the only thing I did today was giggle the ground cable and everything was tight.

unrealii

eurika! I found my bag of spare cross over screws. I had lost one a while ago and I have been wanting to try this configuration for a while.

new configuration:

hu hi out -> polk cross over -> front tweeters, rear mids
hu mid out -> front mids
hu sub out -> sub

I forgot what the cross over freq's and slopes are. I can look them up and post them if anyone is interested. I know the hi out on the hu is pass through.

Will drive the car for a few days and see how differenit it is from a pure bi-amp setup.

For some reason all the rust I cleaned off the cross overs magically has reappeared...or at least on the screws These things are sitting at the top of my trunk...figured they wouldn't rust up again. I hope this isn't hurting any performance.

unrealii

Update on the problem with the amp. It is indeed the amp's cross overs. I disabled them, and have been using the hu cross over for 4 months without any problems.

Now I am using a combination of the hu & polk cross overs for the configuration above.

MacLeod

Ya really need to get another amp. Youre missing out on a lot of SQ.

unrealii

Actually running it biamped with the hu providing the cross over points sounded really good. It surpassed any other sonical clarity I have ever heard. Only downside is that if I am not careful, I can damage the tweeters very easily - which almost happened.

I missed the rear fill because when people are in the car, they like me to blast the music. This new configuration doesn't sound as good as the previous one, but it doesn't sound like I have given up much either. btw, I am still adjusting the setttings on the hu and amp...who knows, it may just be as good. Figured since tweeters dont use a lot of power, might as well use the rest for the rear ...runs and hides:p

I wish I could get a new amp, but I dont have the disposable income (I would buy a 4 channel and a mono amp this time), nor the time to unmount/mount the new amps. I paid only $250 for this mtx 5 channel, so I am definitly getting my money's worth. I still have good guys warranty on this baby...if it breaks, it can be fixed for free. Just not in the mood right now to take out the back seat and wait 2 weeks.

unrealii

SCORE!!

This eclipse radio lets me store 5 profiles each consisting of cross over settings, peq, and time alignment. Now I can turn on and off my rear fill at the touch of 3 buttons

neomagus00

haha... yep, eclipse is pretty cool

MacLeod

Dont feel the need to do without rear speakers. The only real downside to them is the pulling of the stage to the rear and the loss of a little detail. However it does make the sound a little fuller. If I ever had a Suburban or Tahoe or the likes Id run rears.

If you want em, get em!