Parasound Amplifier Hum? (amplifier hum in general? what is it, how do we combat it?)

msg

Like the subject line says, I'm curious about amplifier hum.
What is it?
How do I hear it?
When do I hear it?
How do we combat it?

I'm reading a little outside the site, but also wanted your input as well. Someone mentioned to me to look out for hum on Parasound amplifiers. I don't know what the deal is on this, whether it's even anything I'd notice, etc., but just thought it a good topic for input and discussion.

cfrizz

This is a common problem with big amps. You've probably got a ground loop issue somewhere. The easy and cheap way to fix it is to get a three prong to two prong plug. plug the amp into the plug and put the plug into the wall. Nine times out of ten this will take care of it.

I'm sure the guys will be along any minute to tell you the long drawn out expensive way to deal with it as well.

msg

cfrizz wrote: »

I'm sure the guys will be along any minute to tell you the long drawn out expensive way to deal with it as well.

hahaha

well, I don't have the problem yet (no amp), but just curious about it, and whether it means there's something wrong with the unit, whether it means to pass on the unit, etc.

billbillw

More common with older amps, often a sign of failing power supply caps. My Parasound HCA-2200ii had pretty good hum. I replaced all the mid-sized caps in the power supply and it went away. My Halo A21 never had any sort of hum, not even when I used with with my HT receiver (which was fed from the satellite box). Ground loop hum is also common, especially when you have a cable/satellite feed connected electrically.

cfrizz

I bought a Parasound 1500A brand new and when I plugged it in had a hum so I don't really think it has anything to do with the age of the amp. I came on here frantic asking for help cause I didn't know what was wrong. After tons of advice I tried the cheater plug...problem solved.

steveinaz

Some Parasound amps have a "gound lift" switch---though the HCA-1500a does not. As Cathy stated, get a cheater plug or prepare for a ground loop troubleshooting session. (How did we ever survive before 3-prong outlets?)

This isn't a Parasound exclusive "problem."

tonyb

Better yet, don't worry about something that hasn't even happened. You'll drive yourself nuts with the various things in audio that could go wrong.

msg

It came up in a discussion with a potential seller, so I was wondering what it was about and whether it indicated a problem with the unit, or how much was normal, if any, etc.

steveinaz

msg--ground loop hum can be caused by a number of factors; it's usually caused by cable/satellite boxes with a different ground potential--IF somehow interfaced with your sound system. Sometimes the intermixing of 2 prong plug components (chassis grnd) with 3 prong plug components can manifest a hum as well.

The most effective way to troubleshoot is by connecting 1 component at a time, and listen for which component introduces the hum. Start with amp and speakers only; turn the amp on----if you have no hum, then it's not the amp. Connect the next component, and so on.....Once you find the "offending" component, then you have to figure out why it's creating the hum. Always trade out interconnect cables first---as a broken shield wire can cause hum.

recoveryone

new tag name for MSG.....AKA The Worrier!

Glen B

msg wrote: »

Like the subject line says, I'm curious about amplifier hum.
What is it?
How do I hear it?
When do I hear it?
How do we combat it?

I'm reading a little outside the site, but also wanted your input as well. Someone mentioned to me to look out for hum on Parasound amplifiers. I don't know what the deal is on this, whether it's even anything I'd notice, etc., but just thought it a good topic for input and discussion.

Well, there is hum that you hear through the speakers, the causes of which have been mentioned, then there is mechanical hum or buzzing that comes directly from the amplifier. The latter is most often caused by either a loose power transformer mounting bolt, or DC offset on the AC mains. Electrical devices with brightness, temperature and speed controls that draw power from the mains on only 1/2 of the AC cycle are often the culprits. All it takes is a couple hundred millivolts of DC to cause a toroidal transformer to saturate and hum or buzz audibly.

falconcry72

Glen B wrote: »

...then there is mechanical hum or buzzing that comes directly from the amplifier.

This is probably what the seller was talking about, since it is common on some Parasound models.

msg

steveinaz wrote: »

msg--ground loop hum can be caused by a number of factors; it's usually caused by cable/satellite boxes with a different ground potential--IF somehow interfaced with your sound system. Sometimes the intermixing of 2 prong plug components (chassis grnd) with 3 prong plug components can manifest a hum as well.

The most effective way to troubleshoot is by connecting 1 component at a time, and listen for which component introduces the hum. Start with amp and speakers only; turn the amp on----if you have no hum, then it's not the amp. Connect the next component, and so on.....Once you find the "offending" component, then you have to figure out why it's creating the hum. Always trade out interconnect cables first---as a broken shield wire can cause hum.

thanks! that's a good troubleshooting process

recoveryone wrote: »

new tag name for MSG.....AKA The Worrier!

hahaha! ah c'mom! am I being neurotic? crap. I'm trying to be informed

Glen B wrote: »

Well, there is hum that you hear through the speakers, the causes of which have been mentioned, then there is mechanical hum or buzzing that comes directly from the amplifier. The latter is most often caused by either a loose power transformer mounting bolt, or DC offset on the AC mains. Electrical devices with brightness, temperature and speed controls that draw power from the mains on only 1/2 of the AC cycle are often the culprits. All it takes is a couple hundred millivolts of DC to cause a toroidal transformer to saturate and hum or buzz audibly.

ahhh, good info. he was in fact talking about hum at the speaker though.

falconcry72 wrote: »

This is probably what the seller was talking about, since it is common on some Parasound models.

yeah, at the speaker.

lbcgav

Sorry for resurrecting an old thread, but I just wanted to comment on this topic. I recently purchased a Parasound HCA1200 II and fully recapped it. After a couple months, I noticed a buzzing noise coming from the speakers on both channels. I tried the ground lift on the back and that didn't improve things. I then started unplugging components from the power strip they were plugged into. I have a separate power strip for the power amplifier with nothing else plugged into it. After unplugging my OPPO DVD player, the hum disappeared. I then plugged the OPPO into the same power strip that he Parasound power amp is plugged into and the hum did not reappear. I can't explain why that got rid of the buzz, but it did. Just thought I'd share my experience.

msg

Good contribution.

I think I originally started this thread when I was amp shopping and someone I was talking to said that Parasound amps hum. A touch of neuroses in the beginning, for sure, overwhelmed with gear decisions, and not wanting to mess up. I did end up with a Parasound amp, and I did end up with ground loop hum at the speakers later that year.

Do you have cable tv, by chance? if so, I'd be curious to know whether disconnecting the coax from the wall as a test also stops the buzz in your case.

It turned out to be the coax in my case, though I can't recall how I had everything set up before. Mine was a classic case of a secondary ground for the cable service, since it comes in at the other end of the house as my power does. I ended up rearranging the living space toward then end of the year that this post was made, and made a few different system changes at the same time, and the buzz/hum went away. Didn't investigate enough afterward to figure out the differences, but I suspect it was running the coax through a Panamax power center, though can't recall specifically whether it was already connected that way before. All I knew is that I pretty much just forgot about it, and then realized one day later on that it wasn't buzzing/humming at the speakers anymore.

side note: I've never really understood why people on forums (not so much around here) pounce on others for posting on or "resurrecting" an old thread. If it's relevant to the topic, who cares when the info's contributed. imho, that's the whole point of knowledgebasing.

I see people sometimes say, "this thread is xx years old" and then I see people say, "try using the search function before starting a new thread". it's probably the same whiney fools making both comments.

Jaybeez

I had a horrible hum from a studio subwoofer (Pro Audio) and got rid of it with this: http://www.musiciansfriend.com/accessories/ebtech-hum-x-hum-exterminator

I've downsized the recording portion of my space, and replaced much of the gear with audio, including a Rhythmik sub, which I have plugged into the ebtech unit.

afterburnt

This thread is 27 years old, try using the search function before starting a new thread and making me look at it and ruining my life you heartless bassturd!

voltz

your wrong by 24.5 years but 27 years ago I was out at the lake wishing I had brought more beer

I did use a hum-x to remove a hum from a headphone amp.

skrol

I had a hum issue with a Parasound Pre and Main amp when I had them plugged into different power outlet circuits when I was working on them in my shop. Once plugged into the same circuit, the hum was gone.