bridging channels on my amp...

[jwpb00]

I would like some advice about bridging my amp channels...

I currently have a 75W X 4 Alpine amp and it is currently powering my front component speakers on channels 1 & 2. I don't think I'm going to get a sub and I have pretty sensitive rear speakers that provide good fill so I'm wondering if bridging channels 1 & 2/3 & 4 would be beneficial in terms of sound quality when playing my components at higher volumes.

I should mention that I have Alpine spr-57ls components that have a pretty low sensitivity rating (85db) and 60w RMS specs.

I'm also interested in any general advice about bridging and things to be careful of so that I don't damage my system.

Finally, a question about the crossover setting on my amp...the Alpine components have a frequency response of 35-30 hz but my amp crossover is set at 60hz right now. Should I match it with the frequency response of my speakers and drop it down?

Thanks for your input!

 

[tsunami]

60hz sounds a bit low, but without a sub you have no low end fill.... i would suggest getting a small sub and using the other two channels for that... you could surf the forum market place and possibly pick up a small 8' sub or buy one new from crutchfield, with 150 watts to play with its not like you are going to be bumpin down the street or anything it will just fill out the low end, then you can turn the cross over up on the comps to 75-90 hz and be a bit safer depending on how loud you like to play it...

 

[NoRotorNoMotor]

75 watts is plenty for a 60 watt RMS set, bridging could blow them if you play them too loud

I agree bridging the other 2 channels with a decent 8-10" sub would be the best option

 

[tsunami]

just a warning be careful playing those comps to loud with a 60hz x over (just re-read your post) as the lower the freq and the higher the vol = more chance for distortion and distortion is what makes speakers sad...(plus it blows them)

 

[jwpb00]

Thanks tsunami. The speakers actually sound really good at 60hz although a few people have cautioned me about it. Does the crossover setting basically prevent sound under 60hz to come through the speakers? I've always been confused about this. If so, why would it be a danger if the frequency response range starts at 30hz. I'm sure there is something that I don't understand. One thing working in my favor is that the alpine comps are really inefficient at 85db. Looking back on it, I probably would have been better off with component speakers that have a frequency respone of 45 - 22 hz (and a 90db fr) as opposed to the alpines that have a response of 35 - 30 hz.

Also, I did hook up two 8 inch kicker subs in a sealed box that I had from an older car. I wasn't that impressed with the way the system sounded so I took them out b/c it took up so much room in my trunk. I set my comps at 80hz and the subs at 60hz low power on channels 3 & 4. Now, I'm just thinking about getting some decent rear speakers for better fill of the lower frequencies and driving them with the power from my alpine head unit.

One thing I've learned pretty quick is that it's actually a real challenge to create a really good car audio system. On top of it, most car audio places care a lot more about just selling you a bunch of equipment then they do about creating a system that really fits your needs.

 

[tsunami]

you didn't have the subs crossed over right....

you need a hp (high pass) for your comps at 80hz or so with subs, lower with out, and your subs need to be around 80hz with a lp (low pass) filter setting. once you get those in there then start playing with the filters to get the sound you want. you can also play with the db slope setting as well to get a different sound and you want to usually make sure your slopes match... basically i would put the subs back in there, though two subs with only 150watts isn't a whole lot but try it, and see if it sounds better doing what i suggested

 

[chuyler1]

To answer your question about your speakers playing 30Hz-30KHz. Their rating just means the speaker is capable of playing 30Hz. However, if you sent it a 30Hz test tone at 75watts...the speaker would blow in about 30 seconds. Manufacturers like to stretch their statistics for buyers that don't understand how speakers work. A 6.5" speaker cannot play below 60-80Hz at highway listening levels. When you allow it to play these frequencies you are at a greater risk of blowing the speaker. If you cut them out using a high-pass filter at 60-80Hz the music above that frequency will sound much cleaner and chances are you won't miss the low end that much. If you are the type of person that wants to here all the frequencies, I suggest taking another shot at connecting those subs.

What impedence are the subs and how many voice coils do they have? Do you know the model number of them? There is a lot more to car audio than hooking up positive and negative speaker leads. We can help you design the right system but you need to tell us exactly what you have first. You might be able to connect just one of the subs to save space but I need to know the number of voice coils and impedence before I make that decision.

Tsunami is right about the crossovers. If you didn't have them configured properly the subs won't add much to the overall sound. Fronts should be high-pass at 80Hz and subs should be low-pass at 80Hz. If the setting is continuously adjustable its sometimes better to stagger the frequency. High-pass at 85Hz and Lowpass at 75Hz for example. This will provide a smooth transition between the front speakers and the sub mounted in the rear. You can play with the setting and gain on the sub until it blends nicely. It sounds like you didn't spend much time trying to get the subs to work properly.

 

[Solo2Protege]

to maybe make your crossover question a little more clear:

high pass - this is used for satellite speakers (coax or components) if the frequency is set at 80hz, then all freqs from 80hz and up will be fed to the speakers.

low pass - this is used for woofers/subwoofers. If the freq is set to 80hz, then all freqs 80hz and down will be fed to the woofers.

The there's Electronic and Passive. Passive can be as simple as a capacitor or a coil, but generally, these are small boxes with a few components in there and are fixed to match the component set. They may have different setting connections, but each setting is fixed.

Electronic crossovers are user adjustable, have knobs for freq adjustment, require power to work and come in a variety of configurations and features.

There are many different types, and orders of crossovers and many different configurations for passive crossover components...this is just extremely general crossover info.

Tuning a system is not an easy task, but your ears are the only judge, so when you feel it sounds good, then it's set. High end shops can tune it with an RTA (Real Time Analyser) to get it set perfect (or as close to as possible)

 

[NoRotorNoMotor]

my .02, which doesnt fit into the original question, but i still wanted to mention it

keep the levels(bass/treble) flat on your HU so you can actually hear what the artist wanted you to here instead of coloring his/her original intention of what the music should sound like

i always keep mine flat and adjust the sub for the amount of low bass extension i want

 

[WetsuitxNinja]

Norotor your avatar is frightening.

I do the same, flat, but I will sometimes use the EQ to take the harshness off the tweets on certain songs that have an iffy recording that was too treble happy.