System Design Help
#1
02-17-2012, 09:25 AM
Join Date: Dec 2009
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
System Design Help
OK - please spare me the "shoulda bought a bike with a radio already installed" speeches. There's no fun in that.
Here's the system I want to design on my 2010 Heritage:
Harley's Boom Cruiser Mount Windshield system. Already includes a 50w amp, two 3.5" speakers and most importantly, volume control on handlebars.
+
J&M 7.25" lower fairing speakers in ... wait for it... lower fairings.
I know the following:
1) Gonna need a second amp for the lower speakers.
2) I want each of the two speaker sets to be independently removable and still have the other function. The HD speakers already have the wiring designed as such.
3) I want the volume control on the handlebars to operate the entire system. I'm OK with a separate gain control for either the HD windshield speakers or the fairing lower speakers to provide balance.
4) I want the whole system as clean as possible in terms of visuals. That means running the amp for the lowers either in the lower itself or back to under the seat.
My thoughts so far:
The wiring for the HD speakers has to be:
Input: Amp + Volume : Speaker out.
Which means that I basically have to tap into the audio signal at the Speaker out, run that 50w amplified signal into a second amp (I suppose with a trim control), which then goes into the fairing lower speakers.
All of that is simple enough, but this is where not having an electrical engineering degree is holding me up.
What size amplifier do I need for the lower speakers? The normal J&M speaker is 2ohm, but there also is limited stock of 8ohm speakers, which would of course, mean I could run more power to the speakers and not worry about blowing them out with an overamplified signal. We're talking some serious dough here and I don't want to blow up $400 in 0.5 seconds.
The lower speakers are rated at 140w - 170w max power.
Thanks for the help.
Here's the system I want to design on my 2010 Heritage:
Harley's Boom Cruiser Mount Windshield system. Already includes a 50w amp, two 3.5" speakers and most importantly, volume control on handlebars.
+
J&M 7.25" lower fairing speakers in ... wait for it... lower fairings.
I know the following:
1) Gonna need a second amp for the lower speakers.
2) I want each of the two speaker sets to be independently removable and still have the other function. The HD speakers already have the wiring designed as such.
3) I want the volume control on the handlebars to operate the entire system. I'm OK with a separate gain control for either the HD windshield speakers or the fairing lower speakers to provide balance.
4) I want the whole system as clean as possible in terms of visuals. That means running the amp for the lowers either in the lower itself or back to under the seat.
My thoughts so far:
The wiring for the HD speakers has to be:
Input: Amp + Volume : Speaker out.
Which means that I basically have to tap into the audio signal at the Speaker out, run that 50w amplified signal into a second amp (I suppose with a trim control), which then goes into the fairing lower speakers.
All of that is simple enough, but this is where not having an electrical engineering degree is holding me up.
What size amplifier do I need for the lower speakers? The normal J&M speaker is 2ohm, but there also is limited stock of 8ohm speakers, which would of course, mean I could run more power to the speakers and not worry about blowing them out with an overamplified signal. We're talking some serious dough here and I don't want to blow up $400 in 0.5 seconds.
The lower speakers are rated at 140w - 170w max power.
Thanks for the help.
#2
02-17-2012, 09:07 PM
Intermediate
Join Date: Dec 2011
Location: SE Indiana
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
Sounds like you have a good handle already on what you want to accomplish so I'll just comment on "holes" I see:
1. Dunno why your are set on the J&M 2-ohm speakers. I also don't know why you are looking at 8-ohm speakers at all. Why not just get a great quality 4-ohm set (Hertz, Hybrid Audio, JL Audio, Focal, etc)
2. The nominal impedance of a speaker has nothing to do with it's ability to handle "power". It becomes a funtion of Ohm's Law with regard to an amplifier's output given a specific load (2-ohm, 4-ohm, etc). You cannot "drive" an 8-ohm speaker with more power than a 2-ohm speaker. The specs of a speaker are given at it's rated impedance. In other words, an 8-ohm speaker is rated at XXXwatts RMS power handling, the same as a 2-ohm speaker. If each speaker is rated at say, 80 watts RMS, then both will handle 80 watts RMS - regardless of the amp.
3. The biggest issue I see here (for sound quality) is amplifying an already amplified signal. It is the "cardinal sin" of sound quality. Take the most pristine source, then amplify it at the last stage (after processing) is always the goal. If you can find a clean amp that will accept speaker-level inputs then you may not have an issue (but it is not ideal).
4. Lastly - and probably most important - you'll be hard-pressed to find an amp that will meet your goals in the physical form factor you need. I've heard Kicker is coming out with some VERY small amps but I have no info on them. I commend you on your endeavor and I wish you the best of luck with your project!!
1. Dunno why your are set on the J&M 2-ohm speakers. I also don't know why you are looking at 8-ohm speakers at all. Why not just get a great quality 4-ohm set (Hertz, Hybrid Audio, JL Audio, Focal, etc)
2. The nominal impedance of a speaker has nothing to do with it's ability to handle "power". It becomes a funtion of Ohm's Law with regard to an amplifier's output given a specific load (2-ohm, 4-ohm, etc). You cannot "drive" an 8-ohm speaker with more power than a 2-ohm speaker. The specs of a speaker are given at it's rated impedance. In other words, an 8-ohm speaker is rated at XXXwatts RMS power handling, the same as a 2-ohm speaker. If each speaker is rated at say, 80 watts RMS, then both will handle 80 watts RMS - regardless of the amp.
3. The biggest issue I see here (for sound quality) is amplifying an already amplified signal. It is the "cardinal sin" of sound quality. Take the most pristine source, then amplify it at the last stage (after processing) is always the goal. If you can find a clean amp that will accept speaker-level inputs then you may not have an issue (but it is not ideal).
4. Lastly - and probably most important - you'll be hard-pressed to find an amp that will meet your goals in the physical form factor you need. I've heard Kicker is coming out with some VERY small amps but I have no info on them. I commend you on your endeavor and I wish you the best of luck with your project!!
Last edited by TIF2; 02-17-2012 at 09:16 PM.
#3
02-21-2012, 12:07 PM
Join Date: Dec 2009
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
Yes, I might be hosed on having to amplify an already amplified signal, but until I get everything installed and figure out how the HD unit is raising the volume, it might be the only way I can accomplish my pre-requisite that the HD Boom handlebar volume has to control the whole shebang.
As far as smaller form factor amps:
http://www.biketronics.com/products/...D-Channel.html
Is there a problem with these? This would easily be hidden either inside the lower fairing or under the seat.
But back to Ohm's law. It seems to me that if I forgo the second amplifier and wire the four speakers in parallel, it will drop the resistance of each channel and I should end up with more output from the speakers. Or am I misinterpreting something basic?
As far as smaller form factor amps:
http://www.biketronics.com/products/...D-Channel.html
Is there a problem with these? This would easily be hidden either inside the lower fairing or under the seat.
But back to Ohm's law. It seems to me that if I forgo the second amplifier and wire the four speakers in parallel, it will drop the resistance of each channel and I should end up with more output from the speakers. Or am I misinterpreting something basic?
Sounds like you have a good handle already on what you want to accomplish so I'll just comment on "holes" I see:
1. Dunno why your are set on the J&M 2-ohm speakers. I also don't know why you are looking at 8-ohm speakers at all. Why not just get a great quality 4-ohm set (Hertz, Hybrid Audio, JL Audio, Focal, etc)
2. The nominal impedance of a speaker has nothing to do with it's ability to handle "power". It becomes a funtion of Ohm's Law with regard to an amplifier's output given a specific load (2-ohm, 4-ohm, etc). You cannot "drive" an 8-ohm speaker with more power than a 2-ohm speaker. The specs of a speaker are given at it's rated impedance. In other words, an 8-ohm speaker is rated at XXXwatts RMS power handling, the same as a 2-ohm speaker. If each speaker is rated at say, 80 watts RMS, then both will handle 80 watts RMS - regardless of the amp.
3. The biggest issue I see here (for sound quality) is amplifying an already amplified signal. It is the "cardinal sin" of sound quality. Take the most pristine source, then amplify it at the last stage (after processing) is always the goal. If you can find a clean amp that will accept speaker-level inputs then you may not have an issue (but it is not ideal).
4. Lastly - and probably most important - you'll be hard-pressed to find an amp that will meet your goals in the physical form factor you need. I've heard Kicker is coming out with some VERY small amps but I have no info on them. I commend you on your endeavor and I wish you the best of luck with your project!!
1. Dunno why your are set on the J&M 2-ohm speakers. I also don't know why you are looking at 8-ohm speakers at all. Why not just get a great quality 4-ohm set (Hertz, Hybrid Audio, JL Audio, Focal, etc)
2. The nominal impedance of a speaker has nothing to do with it's ability to handle "power". It becomes a funtion of Ohm's Law with regard to an amplifier's output given a specific load (2-ohm, 4-ohm, etc). You cannot "drive" an 8-ohm speaker with more power than a 2-ohm speaker. The specs of a speaker are given at it's rated impedance. In other words, an 8-ohm speaker is rated at XXXwatts RMS power handling, the same as a 2-ohm speaker. If each speaker is rated at say, 80 watts RMS, then both will handle 80 watts RMS - regardless of the amp.
3. The biggest issue I see here (for sound quality) is amplifying an already amplified signal. It is the "cardinal sin" of sound quality. Take the most pristine source, then amplify it at the last stage (after processing) is always the goal. If you can find a clean amp that will accept speaker-level inputs then you may not have an issue (but it is not ideal).
4. Lastly - and probably most important - you'll be hard-pressed to find an amp that will meet your goals in the physical form factor you need. I've heard Kicker is coming out with some VERY small amps but I have no info on them. I commend you on your endeavor and I wish you the best of luck with your project!!
Thread
Thread Starter
Forum
Replies
Last Post
blackflhx
Touring Models
16
11-13-2012 09:31 PM
