Humming/Buzzing Speaker

[admin_exported]

Hi

My setup is as follows:

Rega P1 turntable (brand new, it got delivered today)

Rotel RA-820AX intergrated amplifier

Mordaunt Short MS10 speakers

Basically, whatever speaker is plugged into the
left channel output on my amp (both direct speaker and remote speaker),
I get a humming/buzzing out of that speaker. I have tested both
speakers and I get the same thing with both so it can't be a problem
with the speakers. Whenever I unplug either the + or - connection, the
buzzing will stop, so if there is only one input plugged into the
speaker the buzzing/humming doesn't happen (even if I plug the inputs
in the opposite way round, the - into the + and + into the -), it's
basically when both are plugged in that I get the noise. As I say, I
have tried both the direct and remote speaker outputs on my amp and
it's happening with whatever speaker is plugged into the left channel.

Does anyone have any idea what the problem could be? If so, how do I fix it?

Thanks for your help.

 

[fatboyslimfast]

Firstly, does this happen only on "phono" setting, or does it happen when say "CD" is selected?

Just to rule out anything further up the chain really.

By disconnecting one cable to the speakers, you are effectively disconnecting both (that's how they work), so by doing so you aren't really proving much.

If it's on vinyl, swap the left and right phono leads over - does the humming change sides? If so, it's the Rega that's causing the issue.

If not, and the noise is also there on CD (or any other input) then I'm afraid the Rotel may have expired...

 

[Anonymous]

Has it started when you got the turntable? is the Turntable near the amp? Could be the motor in that case. Do you have a pre-amp for your turntable?, if thats near a power supply or the motor it might cause a hum. If your amps damaged Richer sounds do a service where they charge about 20-40 quid for a basic service and if it's in need of big work they work the extra price out on top. So if it's had it you're only out 20-40 quid instead of £60/hr or whatever they charge at CarlosFandango hifi.

 

[Anonymous]

Hi

Thanks for the responses both fatboyslimfast and cookiemonster.

It only happens on the 'Phono' output of the amplifier as I have switched to CD, Tuner and Aux and there is no humming/buzzing on any of those, just Phono.

The buzzing sound was happening with my old turntable aswell, a Dual CS 505-1, so I'm assuming it's not the turntable itself.

I have swopped the wires over on the back of the amplifier and basically the buzzing is happening with just the + (red) connector on both the direct speaker output and remote speaker output so I'm assuming there is a problem with the amp itself. I bought it second hand (at least I think it is second hand) and it is ridiculously dusty inside the amp itself, as I can see all of the dust through the air vents on the top. I keep meaning to clean it but forget about it. Could this have any link to the problem or does it seem like a much bigger issue?

Thanks for your help.

 

[fatboyslimfast]

I think your amp has had it's day Sir...the chances are that one of the transistors has gone unstable, probably due to the heat generated under that cosy dust blanket...

Well, I think you have two options - get a separate phono amp and plug it into the CD or Tape inputs (they start from £20 at RS but you would be losing sound quality as the rotels have very good phono stages), or get a new Rotel 820/840 - they normally go for around £40 on ebay.

I would probably junk the one you have (or find a use for it somewhere else where you don't have a turntable... bedroom/spare room etc?), and go for another better-loved example. They come up all the time.

 

[Anonymous]

Hi

Thanks for the response fatboyslimfast.

I took the top off the amp to have a look inside to see if there is anything visibly causing a problem, I couldn't see anything. Although there is a big group of transistors (or what look to be transistors) bunched to the right of the amplifier main board and when I move my hand over the top of them the buzzing/humming increases and the further I move my hand towards them the louder it gets. If I put my hands on the metal casing of the amp the buzzing stops, or if I pick it up off the ground, it stops.

Also, there is no to very little sound coming out of the speaker plugged into the left channel now (so it is unusable), the right channel seems fine though. When I set the turntable spinning, the buzzing seems to increase/get louder and when I move the tonearm/cartridge over to the record to play, it increases/gets louder again.

If, like you say, I need a new amp or a new phono stage, what price would I have to pay to get one equal to the quality of the Rotel that I currently have? Are the NAD PP1 or PP2 any good? Or how about the Project Phono Box?

Thanks again for your help.

 

[fatboyslimfast]

Well, that's the rub. A comparable phono stage is going to be at least £60, and you can get a well-looked after RA-820/840/A/BX for less than that including shipping.

I would say that equivalent stages would be the project or the PP2. Cambridge 540P slightly below, 640P slightly above.

My RA-820 (first of the black models, 1982 I think!) is still going strong, and doesn't exhibit any of the issues you mention, so I think you might be throwing good money after bad by buying a new phono stage to go with it - I would expect the rest of the amp to follow the internal phono stage soon...

 

[Anonymous]

Hi

Thanks again for the fast response.

Are there any other comparable amplifiers out there equal to the Rotel RA-820AX? Is there anything available that is either comparable or slightly worse that I could get for a bit cheaper, say £30 or less?

Thanks.

 

[fatboyslimfast]

You might be able to get the 820 for £30, if it's local to you and can pick it up (i.e. avoid the shipping cost).

I got mine in an auction for a Dual 505, 820 Amp, Mission speakers and about 100 LPs for £65, so it can be done.

Trying to keep under £40 rules out most of the main contenders such as NAD 3020/3120, Creek 4040, Mission Cyrus 1, (early) Arcam Alpha etc as people are aware of the amp's heritage and they therefore go for above that figure.

You will get an amp under that price (I was challenged by my brother to get him an amp for less than £20, and managed to pick up a Sherwood something-or-other for £20 delivered!), but for these sort of amps, forum knowledge tends to be limited so it's a case of chuck it and chance it sound quality wise.

Technics, Pioneer and Sony are always solid bargain-basement buys though...

Finally, there is a useful tool that is an "auction sniper" (hint!) which (for a small fee - normally 1% of a winning bid I think) auto-bids for you in the last 10 seconds of an auction, without you having to be by a computer. I've won a lot of auctions using it, and it's saved me quite a bit!

 

[Anonymous]

Are Behringer a good brand? As they sell a cheap'ish phono preamp, and I was just wondering if it is any good. Here is the link:

http://www.behringer.com/EN/Products/PP400.aspx

Thanks for your help.

 

[fatboyslimfast]

It's ok, not up to the stage in the 820, but ok.

Similar thing (Vivanco) available from Richer Sounds for £19.99.

My advice would still be to get a new amp - if the phono stage has died due to the dust, it's only a matter of time before the rest of it will go, and your £20 phono stage will then be money wasted.

 

[Anonymous]

Ok, there has been a bit of a change in the
situation now. I was reading another forum and found a post with
someone else experiencing similar problems to me. Someone replied in
that topic suggesting that they should disconnect the phono cables (the
ones from the turntable) from the amplifier and keep the amp switched
onto the phono output and check if the humming/buzzing was still there.
If it was, it was a problem with the amp, if it wasn't, it was a
problem with grounding and the connection between the amp and the
turntable.

I have just tested this out and when the
turntable isn't plugged into the amp and the amp is still set to the
phono output, there is no humming/buzzing at all. So I am now guessing
there is a problem with the connection between the turntable and the
amp, or grounding issues. I have checked the cartridge/headshell
connections on the turntable and the cartridge is connected correctly
(red wire to red plug, white wire to white plug etc). So now I'm not
really sure what to do, or what the problem actually comes down to.

Has anyone got any suggestions?

Thanks for your help.

 

[gwynne61]

Have you got any mains wires close to the phono cables or crossing them? May be picking up some interference. You could try moving the cables and/or switching off other components like CD player, etc or even temporarily disconnecting them. May rule out interference problems by process of elimination.

 

[deanms]

Hi I've been reading through your thread and have experienced a similar issue with the phono connection and speaker noise on my system.

I've tried virtually everything without success and wondered if you have now found a solution to the problem you were having.

Thank you.

Dean

 

[Anonymous]

The problem might be the smoothing caps in the power supply circuit. We have had to replace these in amps over 12 years old-they dry out internally and go open circuit, this causes the humming noise at 100Hz.

 

[Andrew Everard]

You could try an earth wire from the base of the arm – under the turntable – to the turntable ground terminal on the rear of the Rotel. Although the Rega is designed so the internal wiring of the phono cables earths the arm, it could be that the connections inside the Rotel create a hum unless there's a wire to the amp's terminal from the deck.

It's worth a try – just a thin piece of single core wire would be fine: connect it to the amp's terminal and try touching it on the metal of the arm under the pinth.