Any audio guys out there? Wireless Microphone Recommendation? - Page 2 - PeachParts Mercedes-Benz Forum

mgburg · #1 07-23-2010, 02:22 PM

Quote:

Originally Posted by JamesDean

Most definitely. I took it apart but didn't see anything out of the ordinary wrong. No burnt or broken looking pieces.

If you have access to an accurate frequency counter, hold the mic close to the I/P of the counter (or connect the appropriate antenna) and see if you're even on channel. If the mic is on, then the possibility of the "error" might be in the receiver itself. Usually, the Local Oscillator section of either unit might have drifted off and the internal AGC/PLL circuits can't pull it back on channel anymore. And unless you have the know-how to tweak these boxes, it's just better to have the factory smack 'em around to be sure everything is on channel and within bandwidth.

JamesDean · #2 08-07-2010, 06:42 PM

Quote:

Originally Posted by mgburg

If you have access to an accurate frequency counter, hold the mic close to the I/P of the counter (or connect the appropriate antenna) and see if you're even on channel. If the mic is on, then the possibility of the "error" might be in the receiver itself. Usually, the Local Oscillator section of either unit might have drifted off and the internal AGC/PLL circuits can't pull it back on channel anymore. And unless you have the know-how to tweak these boxes, it's just better to have the factory smack 'em around to be sure everything is on channel and within bandwidth.

A thought: If the AGC/PLL's can't get the unit back on channel wouldn't it not work period? At any range?

..more thinking....

Or is it the case that the signal is so strong (at close range) that it saturates nearby frequencies to the point where its within the range of the ACG/PLL's ability?

mgburg · #3 08-08-2010, 04:31 AM

Quote:

Originally Posted by JamesDean

A thought: If the AGC/PLL's can't get the unit back on channel wouldn't it not work period? At any range?

Without getting into a ton of details, I've seen satellite dish LNBs float in and out of PLL. Their AGC circuitry would heat up/cool down and the LO would just follow along. Locked, unlocked, somewhat locked, REALLY UNLOCKED, etc., etc., etc... This occured on high-end LNBs too...the $2K and more style. Sucked when it happened. So, imagine a less expensive piece of gear having a "flakey" or marginally designed AGC/PLL. Now, paddle THAT boat out into the middle of the lake!

Quote:

Originally Posted by JamesDean

Or is it the case that the signal is so strong (at close range) that it saturates nearby frequencies to the point where its within the range of the ACG/PLL's ability?

Actually, the "front end" can get so saturated that the LO in the Rcv'r can start generating harmonics and then...you're screwed. That's why good gear is so damn expensive...the manufacturer has TESTED for that very situation and they've probably designed/re-designed their gear to eliminate such problems. But others, not so. So in this case, youse gets whats youse pays for.

And lately, I've seen two situations where the PLL has been so badly screwed up, you have to shut the system down, re-boot and TRY NOT to duplicate the situation again that caused the lockup.

It really comes down to cheap vs. well-designed (meaning...more expensive).

AND ONE OTHER, FINAL THOUGHT/EXPERIENCE...

A lot of times, you can turn on the gear and the transmitter and receiver will "play nice" with one another. But, due to age, all it takes is one or both items to finally get "up to temperature" and then, all bets are off. The transmitter will "float" high and the receiver will float "low" or vise-a-versa. Or, one shuts down and the others wanders all over the place...

Proper/regular maintenance is the only sure way to be sure you have a chance that everything will work nicely.

Remember: For each piece of gear in the chain, your chances for failure increase an additional 50% for each and every item.

It's amazing to think about it...our cars start practically every time we turn the key.

JamesDean · #4 08-07-2010, 06:38 PM

I'll have to look into that. Sounds interesting.

I am actually at a wedding now with the new Sennheiser. Weirdest thing happened. I started it up, ran the frequency scan, synced up the units, and all was well. We started testing it around the room, excellent reception.

Now the weird: I had the RX mute on and the microphone was just sitting on the table here and all of a sudden the AF meter peaks likes someones yelling into it...I'd have thought wit the RX mute on it wouldn't be listening and wouldn't have that problem.

I rescanned the frequencies and changed mine to slightly higher, seems ok so far.

cmbdiesel · #5 08-07-2010, 06:44 PM

Quote:

Originally Posted by JamesDean

I'll have to look into that. Sounds interesting.

I am actually at a wedding now with the new Sennheiser. Weirdest thing happened. I started it up, ran the frequency scan, synced up the units, and all was well. We started testing it around the room, excellent reception.

Now the weird: I had the RX mute on and the microphone was just sitting on the table here and all of a sudden the AF meter peaks likes someones yelling into it...I'd have thought wit the RX mute on it wouldn't be listening and wouldn't have that problem.

I rescanned the frequencies and changed mine to slightly higher, seems ok so far.

Congratulations. You just got stepped on. Someone else is on the same frequency. The receiver is always on, turning off the mic does not stop it from looking. That is why you always try and set up your wireless units where you can see them, and look at them fairly often.