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Hiss from Meridian M2

garyi

garyi

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When I got these speakers there was always a slight background hiss, I guess slightly worse by the fact I am using them incorrectly as nearfield.

However in the left speaker particularly its got noticeably worse just recently. At lower volumes I can hear the hiss as loud as the music.

I paid too much for them as it was so paying the same again for servicing is not palatable. Any thoughts on where I would begin, caps I am guessing?

Allegedly they were serviced in 2018 but the paper work which was blurry on the ebay listing was never included.
 
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This is the daughter board the guy refers to in that link.

There are two do hickeys one on each end that seems to be set up to get hot as they have ceramics coats but the area around them is dark. Anything to worry about?
 
A schematic I see online suggests one NE3352 and 3 LF353N. Does this match your board?

It's important to put the right part in the right place.

Whether changing the opamps will make any difference, IDK, but it's plausible.
 
Mine all say NE5532P

There are four of them.

It must have known I was poking around now its making strange noises, like slight earthing or feedback which comes and goes.

Sigh.
 
@garyi - Right, now re-seat all of them... firmly. (yes, chips can 'walk' out of insertion sockets like that pictured over decades for thermal-cycling reasons, or if simply bumped in transit etc.)

TBH - the NE5532 is the better opamp by far. Stick with what you have.
Out of pure interest, if not too late - can you post a pic of the other side of the pcb above?
 
Hi Martin I'll get it back out tomorrow

Do you mean I should order some more of these amps?
 
I did reseat all of them and once I fixed the stray leg I must say its much quieter. This being said this amps seem to be like 1.60 each which I can afford for a punt.
 
The schematic I saw has LF353 on the input and no coupling caps. The LF353 is a FET input opamp which requires negligible bias current, the NE553x is bipolar input and the bias currents need considering. So while in general the NE553x is about as good an audio opamp as you actually need (as opposed to don't really need but can't bear not to have the best) it may not be optimal as a direct replacement.

I have a sort of memory of the Quad 405 being considered noisy and the LF353 on the input being blamed. Not sure blame was being correctly distributed, but there you go.

I'm sure Martin can be authoritative.
 
… very, very far from..!

(Not knowing a thing about the m2 circuit design, it’d be insructive to me to read-up & find out a lot more first. …)
 
I have to say the board, particularly on the back looked very, um, agricultural. I am not sure if this is just early meridian stuff or if someone 'ad a go'
 
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One of the square dodads bottom right there was loose on one side, I gave that a dab of solder but am not sure if I dislodged it.

I gave it a squirt of contact cleaner. Its silient now!

Even so if anyone can advise the right parts to get they are so cheap I would consider it a no brainer.
 
Talk to me someone I have itchy fingers here, do the letters/numbers code above the part. number mean anything?
 
Could be simply unplugging and reseating the chips has cleaned/scraped oxidation of the legs and chip holder, solving your issue. Oxidation over time can cause connections to increase in impedance causing noise issues.

Annoying as you haven't replaced anything do have done nothing to fix it... but its working.

It's even more annoying in the digital domain as stuff goes from not working at all to being fine again.
 
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