2. tech-talk
  3. 1104342274

An unusual problem that merits an unusual solution

Hello all,

I recently aquired a Marantz AV-550 preamp and 5 MA-500 monoblocks, and now I'm running into an odd problem. Any time the preamp gains and loses signal, there's a loud, "POP!" in the right surround channel. This means that any time you do *anything* to the DVD player - pause, cue, review, chapter next, menu - the right surround pops loudly.

Because I'm not sure this is a repairable problem, I'd like to just cut down the volume of said "POP". My idea was this:

The volume of the preamp does not affect the volume of the pop. Therefore, if I could wire an in-line resistor of some sort between the preamp and the amp, it would cut down the volume of the channel, and I could just turn up the volume of that surround channel in the preamp to compensate.

My question: does anyone make an RCA coupler which has a resistor or potentiometer built into it, or will I need to build something?

If I have to build something, what would be an appropriate level of resistance to use, or should I use a pot?

Thanks in advance for lending your expertise,

Scott
hudsonhawk
hudsonhawk OP
137 posts
 
Interesting, makes me wonder if it's something with that (now seemingly ancient) Yamaha AC-3 decoder chip in the AV-550's. Mine may be popping in the LFE channel as well - but I have no sub to hear it with.

Looks like I may have found a solution though - someone emailed me and pointed out the Rothwell in-line RCA attenuators (man I wish I'd known about those when I had my Jolida Tube Amp - it's gain was *way* too high!)

I'm also going to order the Channel Vision 15k Ohm inline resistors as a backup (and for comparison).
sean
6,231 posts
 
I know that this is just a long shot, but have you ever verified that your AC outlets and your gear were properly polarized? Something else to think about is static electricity build up. This time of the year, the dry air and static can cause all kinds of erratic behaviour. We've had reports here of people blowing out digital circuitry just from touching their gear after walking across the carpet i.e. static discharge arcing from the person into the components. Sean
>
hudsonhawk OP
137 posts
 
Just for reference to anyone else who has this problem in the future, I was able to get -6dB attenuators from Parts Express that did the trick nicely.

The "pop" is still there - but it's so much quieter you can barely hear it anymore.

Oddly enough, there's a new sound that's appeared since adding the attenuator - any time the Marantz receives an IR burst - even if the IR is intended for another component - I get a wierd beeping from the same troublesome right surround channel. It sounds sort of like a modem or a fax machine, and is only a second or two long.

Clearly the preamp has issues, but it should get me by until I can afford an Acurus Act-3 or an Outlaw 950. Considering I paid 70 bucks for it on Ebay, I don't really have any right to complain!

Thanks for the suggestion, Sean; no luck however. Our power does seem very dirty and unstable - it's an old house with old wiring in a dense urban neighborhood, and I'm sure that doesn't help. If I could afford a nice power conditioner, I'd get one, but AC stuff is just too expensive. Especially having the quintet of MA-500's - that's 5 outlets right there!

Thanks to everyone for their help in this thread, and over email.
More to discover