Changing Amp Setup, Speaker RMS Question

[GSG2Teg]

I have a Alpine CDE-HD149BT, 2 Alpine MRV-F340 Amplifiers (55w RMS x 4 @ 4 Ohms, 130w x 2 @ 4 ohms(bridged)), 2 6.5" 3-way Pioneers (50w RMS, 300w max) for the fronts, 2 6.5" 2-way Pioneers (40w RMS, 250 max) for the rears, and a set of 1" Alpine Type-R component tweeters in the rear that are left overs from a previous install . I'm rearranging my setup and it so happened to occur to me that I have some extra ports on my amplifier to bridge. I was thinking of having one MRV-F340 for the front two pioneers, and having the other MRV-F340 powering the tweeters and the set of 2-ways in the rear.

If I am short on watts I've always bridged to try and match the speaker RMS. However, I've never actually bridged and had ample space to work with. I was thinking about bridging the two front speakers to have 130w x 2 instead of the 55w, definitely hitting the RMS point(50w), but since I'll be running my rears at the 55w range (which is still hitting the RMS for those (40w)) would this be any significant difference in quality or should I run both sets at 55w to kind of keep both sets of speakers matched? Which in that case I could bridge the tweeters to run 130w RMS. I am not using the 6.5" Type-R components main drivers any more since they blew a while ago, but I am still using the filter/separator device they came with. I just forgot what those are rated at.

Or if you guys have any other suggestions on design, feel free.

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[r0llinlacs 10+ year member]

Highs will always sound better at higher impedances, bridging will make it mono (unless it's a 4 channel with 2 speakers bridged for stereo) and lower the impedance to 2 ohms which doesn't help sound quality.

If you bridge one set and not the other, the bridged set will be louder and will require some tweaking to even them out with the rears, and also will be at 2ohms instead of 4ohms, which will make them sound different than the 4ohm set.

 

[GSG2Teg]

I didn't think about stereo/mono. I would most likely be splitting the rca's to turn the 4 channel amp into a two. There is another switch or option on the amp to strictly get signal from like channel 1/3, or 1/4 or all of them, I'd have to look again to be for sure. But I thought it would all run the same 4 ohm impedance. But if the highs do sound better I might just have to run the tweeters at the higher wattage and not have to do too much adjusting on the others.

 

[r0llinlacs 10+ year member]

I didn't think about stereo/mono. I would most likely be splitting the rca's to turn the 4 channel amp into a two. There is another switch or option on the amp to strictly get signal from like channel 1/3, or 1/4 or all of them, I'd have to look again to be for sure. But I thought it would all run the same 4 ohm impedance. But if the highs do sound better I might just have to run the tweeters at the higher wattage and not have to do too much adjusting on the others.

If you bridge two channels to one speaker, the impedance drops at the amp instead of the speaker, so any two channels bridged will always be the same as bridging two speakers on one channel and the ohm load will drop.

To be honest, with what you have, what I'd do is put the tweeters up front, disconnect the tweeters on the front co-axials (if you can) and run one channel to each woofer and tweeter on the front. 1 channel per tweeter and 1 channel per mid and have it like a component set-up. But even if you keep the tweets in the rear, I'd sill do one channel per speaker and hook the tweets to their own channels. Everything will be 4-ohm and even from front to back and the tweets will have their own channels which gives better tweeter/mid separation. Are you using the crossovers that came with the tweeters?

Also, I definitely wouldn't overpower your door speakers if you have nothing for a sub. Door speakers can't take bass like a sub can and they won't last very long overpowered if you're using them for full range w/ bass.

 

[GSG2Teg]

I think my overall design will be splitting both my front and rear RCA's into 4's having one 4 channel amp being for front and one being for rear. I would possibly have to do another split on top of that if I was going to bridge a single set in the rear making me use one amp for front/rear, and the other for rear. I was just going to install the fronts as is using 2 of the 4 channels but realized I could push more power to them by bridging. I think sound wise yes it would sound fuller and louder, but having that sound difference between the two/three sets would it be that noticeable? I do have time/spatial on the deck to tweak as well.

Not to switch subjects.. As I was going over my manuals I was looking at the gain function. Back in the day I was always informed to turn your gain down, turn your volume up till you hear distortion, turn it down a notch, then adjust your gain up till hear distortion then turn it down a notch, then just remember to never go past that number. However, in the manual it's showing that the "nominal" gain setting is 4v. As for my deck, it puts out 4v as well. I don't know if it's that easy or what but wouldn't that indicate to set the amp gain at "nominal" and just adjust everything else accordingly? I've been looking at ohms law to see about adjusting the gains that way as well but haven't had a chance to really play with anything yet since I'm cutting new panels.

 

[GSG2Teg]

Yes, I am using the crossovers that came with the tweeters. And yes, I was trying not to drop impedance if I could. What I actually had set up was one amp for fronts and rear. The rear channel went into the crossover, then from the crossover it split off into the tweeters and then splitting off into the 6.5" 2-ways as the mids..possibly cutting out some highs that went to that set. I was using the other amp for a set of two 10" Pioneers because you are correct those kind of door speakers can't handle bass, especially comparable to say like a 6x9.

 

[r0llinlacs 10+ year member]

Yes, I am using the crossovers that came with the tweeters. And yes, I was trying not to drop impedance if I could. What I actually had set up was one amp for fronts and rear. The rear channel went into the crossover, then from the crossover it split off into the tweeters and then splitting off into the 6.5" 2-ways as the mids..possibly cutting out some highs that went to that set. I was using the other amp for a set of two 10" Pioneers because you are correct those kind of door speakers can't handle bass, especially comparable to say like a 6x9.

I see. If you set it up one channel per speaker 4-ohm even, you'll have two extra channels and you could always run one or two subs off the two channels you aren't using to give you at least a little bit of decent bass.

As far as the gains, I would just go by ear, even though nominal matches your preouts.

 

[GSG2Teg]

Sort of to clarify.. I read somewhere that every time you split your RCA cables you will only make a difference on your voltage (by a little) and not affect the impedance?

 

[r0llinlacs 10+ year member]

Sort of to clarify.. I read somewhere that every time you split your RCA cables you will only make a difference on your voltage (by a little) and not affect the impedance?

The RCAs will have nothing to do with the final impedance. But splitting the RCA's yes theoretically will split the output voltage in half to each amp but real world it doesn't make quite that big of a difference. Just splitting it two ways you should be fine. How many outputs does your deck have?

 

[GSG2Teg]

3 (front, rear, sub) And I was going to say ya, I was just looking over the amp manual and from the looks of things it's still in 4 ohm's the way I've bridged the subs so far, or any set of speakers that I'm planning on doing that way.

 

[GSG2Teg]

and correction/answer to my gain question.. it says "Set the MRV-F450/MRV-F540/MRV-F340 input gain to the minimum (4V) position." With min., nom., max., and all else in between.. I guess min. would be the 4v position.

 

[r0llinlacs 10+ year member]

and correction/answer to my gain question.. it says "Set the MRV-F450/MRV-F540/MRV-F340 input gain to the minimum (4V) position." With min., nom., max., and all else in between.. I guess min. would be the 4v position.

Just do it by ear how you described. That's how you do it without an oscilloscope.

I just looked up your amp to be sure and the input switch on your amps will split the signal so you won't need to split the RCA's. Switch it to 1/2 and you will have output on the other two channels.

 

[GSG2Teg]

Just do it by ear how you described. That's how you do it without an oscilloscope.
I just looked up your amp to be sure and the input switch on your amps will split the signal so you won't need to split the RCA's. Switch it to 1/2 and you will have output on the other two channels.

Sweet thanks man! I haven't messed with the outputs yet, I remember reading something about that switch way back when the amp first came out but never really needed it. I just recently came across this seconded MRV and the possibilities are running through my head.