Audio Upgrade - Does anyone know what specific load the amp is looking for?

[mikevoth]

I didn’t see a thread on this already, so here goes. Forgive me if I missed it/them. I’m engineering a large audio upgrade on my '24 RTL. I have everything planned and mapped out, but one question remains. I’m assuming the factory amp is looking for a signal/load when powered on. I know Harley’s have to install 47-ohm inline load resistors on each channel to trick the factory amp into thinking all is good. Also, I'm assuming I will need to do the same for all 6 channels of my Spyder. Does anyone know what specific load the amp is looking for? If I had some kind of variable load tester, I’d experiment, but I do not. There’s not a whole lot of information on the web about this, and the service manual is very lacking in this department for diagnostics. TIA

 

[Albec]

I know very little about the audio system on the Spyder, so please forgive this question.

Are the speakers connected directly to the amp(s)? If so, you can measure the resistance of each speaker to determine the load. Yes, I know that measuring the resistance of a speaker with a DMM isn't exacting, but it's close enough for this I believe.

To test the impedance of a speaker, this is the actual variable needed, normally an impedance bridge is required.

 

[mikevoth]

I know very little about the audio system on the Spyder, so please forgive this question.

Are the speakers connected directly to the amp(s)? If so, you can measure the resistance of each speaker to determine the load. Yes, I know that measuring the resistance of a speaker with a DMM isn't exacting, but it's close enough for this I believe.

To test the impedance of a speaker, this is the actual variable needed, normally an impedance bridge is required.

Yes, all six channels come directly from the amp. I can measure when I remove the speakers, I just wanted to have what I needed before tearing this thing apart. If no one knows, I’ll continue with testing.

 

[Albec]

Yes, all six channels come directly from the amp. I can measure when I remove the speakers, I just wanted to have what I needed before tearing this thing apart. If no one knows, I’ll continue with testing.

Are there any markings on the speakers themselves that would indicate the impedance?

 

[mikevoth]

Are there any markings on the speakers themselves that would indicate the impedance?

Yes, the speaker are all 4-ohm. Doesn’t do any good for what I’m trying to figure out though. But… I’ve talked to installers today and all have said the only issue is feedback if a low-end system is installed and subpar wiring. I’m good to go.

 

[Albec]

Yes, the speaker are all 4-ohm. Doesn’t do any good for what I’m trying to figure out though. But… I’ve talked to installers today and all have said the only issue is feedback if a low-end system is installed and subpar wiring. I’m good to go.

If you already know what the speaker's impedance is, 4 ohms, that's the load on the amp, per channel, right?

Feedback? What? Can you elaborate on that?

 

[mikevoth]

If you already know what the speaker's impedance is, 4 ohms, that's the load on the amp, per channel, right?

Feedback? What? Can you elaborate on that?

I’m not sure how the Harley Street and Road Glides work, but I know that they require a 47-ohm load resistor in-line to trick the amp into thinking that the factory speakers are connected, when in fact they aren’t, as a new speaker wire is run from the amp(s). 47-ohm is much higher than the 4- or 2-ohm impedance that can be measured across the speaker terminals. So that is quite puzzling to me. I called a half a dozen installers this past week and let me tell you, NO ONE wants to give up an ounce of info. I was asking technical questions, so they all accused me of being an installer and probing for information. I was told, however, that there is no load requirement for the factory amp to work. It is simply a matter of installing quality components to avoid feedback. I guess that’s the only problem really. I was glad to at least find that out. Verified by 2 installers who would actually talk to me about that, but nothing else. But anyway, I’m getting ready to use my oscilloscope and digital amp meter to measure the clipping voltage and volume of the factory amp, and whether it’s programmed to maintain or cut voltage above a certain level. Also checking to see if the signal is processed or not. This will make a huge difference when trying to calibrate my system with the DSP when I cannot flatten the EQ curve of the factory system prior. I already did a test tone sweep that indicated a full signal being sent to the factory speakers, which is good. Tone played from 20hz - 1kHz (test stopped there). So I'm confident the DSP will at least get the source signal it needs.

 

[Will W]

I don't know exactly what you're trying to figure out and this may be a dumb question, but can I change out the existing speakers with better quality ones like a kicker to improve the volume and sound quality? I wear a beanie lid helmet in the summer and have to crank up the volume pretty much all the way at highway speeds to listen to bluetooth audio. I have a full face modular helmet that I ride my KLR with, and I'll probably want to do the same on the Spyder in wintertime. My wife had hers on during one of our first rides, and she said that the sound volume sucked compared to our Harley.

 

[mikevoth]

I don't know exactly what you're trying to figure out and this may be a dumb question, but can I change out the existing speakers with better quality ones like a kicker to improve the volume and sound quality? I wear a beanie lid helmet in the summer and have to crank up the volume pretty much all the way at highway speeds to listen to bluetooth audio. I have a full face modular helmet that I ride my KLR with, and I'll probably want to do the same on the Spyder in wintertime. My wife had hers on during one of our first rides, and she said that the sound volume sucked compared to our Harley.

I put front and rear Kicker KM44s in shortly after I purchased mine. I took the front ones back out though. You get a little more midbass, but clarity is what you achieve by doing this. A little louder, yes, but with coax speakers in the front and back, the sound was WAY too bright. Still, not nearly good enough for my ears. You’ll need a blade pin adapter for the harness, or cut off the connectors and replace them with a larger size, which is what I did. Not sure exactly when I’m going to have time to tackle this project. Not home much, but I’ll have 2300 watts hitting 7 Cicada drivers eventually. Tuned down pretty far so as not to overpower the 90-amp charging system, and a LiFePo4 battery to handle momentary big drops.

 

[Albec]

I’m not sure how the Harley Street and Road Glides work, but I know that they require a 47-ohm load resistor in-line to trick the amp into thinking that the factory speakers are connected, when in fact they aren’t, as a new speaker wire is run from the amp(s). 47-ohm is much higher than the 4- or 2-ohm impedance that can be measured across the speaker terminals. So that is quite puzzling to me. I called a half a dozen installers this past week and let me tell you, NO ONE wants to give up an ounce of info. I was asking technical questions, so they all accused me of being an installer and probing for information. I was told, however, that there is no load requirement for the factory amp to work. It is simply a matter of installing quality components to avoid feedback. I guess that’s the only problem really. I was glad to at least find that out. Verified by 2 installers who would actually talk to me about that, but nothing else. But anyway, I’m getting ready to use my oscilloscope and digital amp meter to measure the clipping voltage and volume of the factory amp, and whether it’s programmed to maintain or cut voltage above a certain level. Also checking to see if the signal is processed or not. This will make a huge difference when trying to calibrate my system with the DSP when I cannot flatten the EQ curve of the factory system prior. I already did a test tone sweep that indicated a full signal being sent to the factory speakers, which is good. Tone played from 20hz - 1kHz (test stopped there). So I'm confident the DSP will at least get the source signal it needs.

Sounds like the installers didn't like you picking their brains without getting compensation, one cannot blame them for this at all.

If you know how to use a 'scope then it sounds like you're quite knowledgeable.

I'm confused about this feedback you mentioned and that a 47-ohm resistor is required to eliminate it. This seems very strange to me, what feedback and where is it coming from?

 

[mikevoth]

Sounds like the installers didn't like you picking their brains without getting compensation, one cannot blame them for this at all.

If you know how to use a 'scope then it sounds like you're quite knowledgeable.

I'm confused about this feedback you mentioned and that a 47-ohm resistor is required to eliminate it. This seems very strange to me, what feedback and where is it coming from?

No doubt! I was thinking I wouldn’t get any info and showed my appreciation. Time is money. But yes, I’ve watched several videos, particularly from Volunteer Audio. No clue why the use of a 47-ohm resistor is required for the Harley’s. That raised quite the red flag for me. Our Spyder electrical system is quite advanced and many processes going on behind the scenes that I really want to understand and do my best to avoid. The communication between the factory amp and the dash raised the red flag for me. Fortunately, it’s not the same as the Harley’s so adding a pro level audio won’t be as difficult as I worried it might be. Also learned about the use of the XS Titan 8 LTO battery for high demand audio. Gamechanger. Our charging system produces ~1200 watts and 90 amps. The Harley’s alternator tops at 54 amps (according to Volunteer Audio). Only thing, I don’t think their group 20 battery will quite fit in our stock location. We have the height, but the LTO battery is about a half-inch deeper. Next hurdle to overcome. Check out that battery technology. Nothing like it.

 

[Albec]

I went the other way for my Spyder audio. It's all in my helmet.


Cardo System bike intercom that uses high-quality JBL drivers in the helmet. These sounds GREAT! It's like having a quality pair of headphones on, it's that good to my tired old ears anyway.