Autocom fidelity

[Fred W]

The big (and I mean REALLY BIG) problem with designing a sound system that is also an intercom, which is designed and intended to be used on a motorcycle is the helmet NOISE.

Think about the noise frequencies that you hear when riding without any audio system. You know, the ones that we all (should) wear earplugs so we can prevent ourselves from going any further into deafness than we already are. These same frequencies will be picked up by the microphones in the intercom and completely saturate the audio amplifiers if they are actually linear. Since the purported primary function of any of these audio controller/mixers is as an intercom, it makes all kinds of sense that they would try and make them as insensitive as possible to all that roiling low frequency helmet rumble. So the frequency response cannot be flat or the amplifiers would be completely useless.

Now... who is still surprised that you do not get top fidelity sound out of their Starcom or Autocom? Because if you are I obviously didn't explain it well enough.

 

[MartyA]

Actually I have no issues with the music part of the Starcom1. The sound, while not headphone perfect, is, I thought, remarkably good through the helmet speaker. My problem was with the GMRS / FRS radio fading out in the afternoon and what I think is "clipping,"again, later in the day, from the intercom part. The music never faded or buzzed or any of that, even when Sally's words became buzzy and the GMRS radio stopped working late in the day.

Got an email from the Starcom folks they got my unit and are looking at it. I'll post anything interesting here if no disagreement from anyone.

 

[stpndeep]

The big (and I mean REALLY BIG) problem with designing a sound system that is also an intercom, which is designed and intended to be used on a motorcycle is the helmet NOISE.
Think about the noise frequencies that you hear when riding without any audio system. You know, the ones that we all (should) wear earplugs so we can prevent ourselves from going any further into deafness than we already are. These same frequencies will be picked up by the microphones in the intercom and completely saturate the audio amplifiers if they are actually linear. Since the purported primary function of any of these audio controller/mixers is as an intercom, it makes all kinds of sense that they would try and make them as insensitive as possible to all that roiling low frequency helmet rumble. So the frequency response cannot be flat or the amplifiers would be completely useless.

Now... who is still surprised that you do not get top fidelity sound out of their Starcom or Autocom? Because if you are I obviously didn't explain it well enough.

You are absolutely correct; the road noise is their main challenge. But I am surprised. We all should be! We should expect them to meet their advertised claims. This is what drove some of us to a purchase!

This is a design error that I wouldn't even expect to see from one of my interns. I guess I should not have written the last response with a sarcastic "or am I just overlooking something" comment. I fully understand the design criteria for such circuits. We have many in full production with very successful results with very demanding customers. When designing audio circuits where inputs create undesired effects you DO NOT compensate the signal in the final stages. To be perfectly clear and simple here, the filtering of unwanted signal happens at the input of that source and that source only. So in the case of the intercom, that filtering happens at the microphones input stage. Microphone inputs are the only inputs that would require this compensation in this device since this is the only path for the "roiling low frequency helmet rumble"[SIZE=10pt] you speak of. Altering the final stages alters all inputs, resulting in the unnecessary destruction of all the other sources response. There is absolutely no logic in compensating at the final stage for this problem.[/SIZE]

This faux pas in design is somewhat common with inexperienced design engineers without an audio engineering background or proper guidance, something this manufacturer should consider. And by all means don't mislead the public with claims of performance that they do not achieve.

[SIZE=10pt]Treat yourself to what's possible by auditioning Lexus with a Mark Levinson audio system at a Lexus dealer. After listening for a bit link your cell phone, make a call (opening a microphone) and appreciate the designers for their care and knowledge in the design of the compensation integrated into that input preserving the amplifier stages for your listening pleasure. [/SIZE][SIZE=10pt]Yes, it's a more sophisticated design but the general concepts remain the same.[/SIZE]

 

[Fred W]

Of course you are quite right. These systems could all be designed to work a lot better and maintain higher fidelity. But they aren't. Any of them.

So when can we expect to see your new offering in the motorcycle intercom and audio processing arena?

 

[kleake]

I couldn't agree more with all of the above. I was really surprised at how well the autocom handles the high frequencies, but really disappointed in the lows, but figured they did it so the speakers could handle it better with the lower wattage. And yea,,, why couldn't they tweak the road noise and such on the input side only instead of the output side.... Either way, I would be curious on what you can come up with because I definitely want my tunes to sound better,,, all else for voice it does a good job already. Maybe, we can be lucky enough that they only designed in a capacitive coupling somewhere that isn't allowing the lows to pass, and we could make a small tweak to their design to gain them back.

 

[jwhite518]

I've noticed the lack of low end on my Autocom, but it's not important to me. This thread is interesting because it points out that the problem is in the Autocom, not my speakers.

The main reason I bought my Autocom is because their helmet mic works on a cell phone call at speed. Presumably it would also work on passenger intercom or bike-to-bike, but that isn't my application. The Autocom also integrates my Zumo audio sources and V1 radar detector. I use custom-mold in-ear speakers, which really highlight the great highs and lack of lows of the music. So I can't hear the bass guitar or kick drum that well. Big whoop.