LM4562 opamps are terribly noisy

[kabforks]

Hello.

As some of you might remember, I fried my other pair of LM4562's a few weeks ago. Some new ones arrived today, but they don't work either.

That is, they are extremly noisy and messes with the sound. Worst is the piano, which is almost just noise.

Both opamps in both places (lineout and headphone out) does this. The stock opamp works fine. Is my Beresford TC7520 broken? Opamps, AGAIN? All four of them? Maybe I should try the metal can LM4562?

Another question: What are the effects of opamps anyway? Right now I have none, and although the volume is low, it sounds perfectly fine.

[Maximum]

That's pretty odd. The LM4562 opamps have always behaved quite well for me, sounding quite tidy for the most part. Especially as you mentioned piano as these are often mentioned as quite good for that and more so with the MLC 5/6 mod applied. Stan has also used a pair of HD650 for his testing I believe so compatibility shouldn't be a reason. Well if it is a faulty audio board you should just get a Gator that will beat any opamps you will buy, or just do the passive mod. :eyebrows:

[maniac]

That is, they are extremly noisy and messes with the sound. Worst is the piano, which is almost just noise.



Hi kabforks, do you have a stock unit or unit with Gator module?
I got noise issue with gator only (in Caiman), after I have installed murata regs & Elma caps and then applied caps to muratas to get rid of hiss they produced.
Are you using original PSU or have the ability to regulate the voltage? In second case try to set voltage a bit lower than 13volt. In my case 12.9v avoid noise (or 900Hz hiss if no caps are applied on muratas).

[kabforks]

Thanks for the replies.


That's pretty odd. The LM4562 opamps have always behaved quite well for me, sounding quite tidy for the most part. Especially as you mentioned piano as these are often mentioned as quite good for that and more so with the MLC 5/6 mod applied. Stan has also used a pair of HD650 for his testing I believe so compatibility shouldn't be a reason. Well if it is a faulty audio board you should just get a Gator that will beat any opamps you will buy, or just do the passive mod. :eyebrows:
So thought I. It seems I'm the only one with the problem :|. How will this Gator board beat any opamp? I'd be interested to learn more about that. And what is this passive mod?


Hi kabforks, do you have a stock unit or unit with Gator module?
I got noise issue with gator only (in Caiman), after I have installed murata regs & Elma caps and then applied caps to muratas to get rid of hiss they produced.
Are you using original PSU or have the ability to regulate the voltage? In second case try to set voltage a bit lower than 13volt. In my case 12.9v avoid noise (or 900Hz hiss if no caps are applied on muratas).
I have a stock TC 7520. No Caiman or anything. No mods, except for two cutted resistors (i believe). It was recommended to remove them if used with the LM4562. The powersupply is a standard 12V 1.5A thing, so I cannot regulate the voltage.

[Butuz]

I have a stock TC 7520. No Caiman or anything. No mods, except for two cutted resistors (i believe). It was recommended to remove them if used with the LM4562. The powersupply is a standard 12V 1.5A thing, so I cannot regulate the voltage.

Try this. Unplug and open up your 7520.

Looking at it from the front, remove the left hand op amp.

Plug back in and power up. Has the noise gone? If so I suggest that it is your op amp. If not then it could be a problem else where and maybe Stan needs to take a look at your unit?

If it is your op amps then I would forget fiddling with op amps and either get the Gator upgrade board (if you need headphone output) or do the passive mod (if you don't use headphones, passive mod removed headphone functionality).

Ill be frank - once you go either passive or gator - op amps will be a long and distant memory - these mods blow all op amps out of the water.

I've gone passive mod as i dont use headphones and also a battery powered supply - it's like a different DAC. Big upgrade.

Butuz

[StanleyB]

I have a stock TC 7520. No Caiman or anything. No mods, except for two cutted resistors (i believe). It was recommended to remove them if used with the LM4562.
Which resistors did you cut, and where did you read that mod? It's not one I recognize. I suspect that's the fault.

[kabforks]

Try this. Unplug and open up your 7520.

Looking at it from the front, remove the left hand op amp.

Plug back in and power up. Has the noise gone? If so I suggest that it is your op amp. If not then it could be a problem else where and maybe Stan needs to take a look at your unit?

If it is your op amps then I would forget fiddling with op amps and either get the Gator upgrade board (if you need headphone output) or do the passive mod (if you don't use headphones, passive mod removed headphone functionality).

Ill be frank - once you go either passive or gator - op amps will be a long and distant memory - these mods blow all op amps out of the water.

I've gone passive mod as i dont use headphones and also a battery powered supply - it's like a different DAC. Big upgrade.

Butuz
The noise is gone without the opamp. So yes, and of couse, it could be the opamp. It's just that this is my 4. opamp I'm trying. All with the same result.

I am considering the passive mod and/or gator, since I have a seperate headphone amplifier. Right now I'm very short on £££... lol. Can the gator board and passive mod be compared? Like, is the one better than the other? Does it achieve the samme effect?


Which resistors did you cut, and where did you read that mod? It's not one I recognize. I suspect that's the fault.

It's these: http://www.beresford.me/others/p7hg_img_1/fullsize/2_fs.jpg

From what I can remember, I cut them as a response to the noise... Did not help tough :)

[leo]

I hope you cut the pair of yellow ceramic capacitors (MLC5 + MLC6) , not any resistors?

[kabforks]

I hope you cut the pair of yellow ceramic capacitors (MLC5 + MLC6) , not any resistors?
Yes, that is correct. I cut the MLC5/6. I got the names wrong :P

[leo]

Thats good, just making sure :)
Strange problem, so you tried just one of the LM4562's in the line out socket? (left one)

BTW they are definitely LM4562MA they sent you? this is whats stamped on the actual chip?

[kabforks]

Thats good, just making sure :)
Strange problem, so you tried just one of the LM4562's in the line out socket? (left one)

BTW they are definitely LM4562MA they sent you? this is whats stamped on the actual chip?

Yes. Although the stamp is very, very bad. On one of the chips, I cannot read the name. Somethings tell me these opamps are fake.

This is the relevant eBay-seller:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250638909313&ssPageName=STRK:MEWNX:IT

4 out of 4 chips have this problem. That's not a coincidence :{

[Butuz]

All 4 chips from the same seller???

Butuz

[kabforks]

All 4 chips from the same seller???

Butuz

Yup. I realized I should have made my second buy from another seller :P

[keiths]

I've a spare that was removed when I fitted the Gator to my Caiman. I know that chip is good - pm me your address and I'll post it off to you.

[Butuz]

Yup. I realized I should have made my second buy from another seller :P

Ok I think that answers the question in my mind!! Steer cleer of that seller!!

I also have spare working op amps lying around if for whatever reason keith can't sort you out.

Butuz

[here we go again]

Please NEVER buy electronic components from Hong Kong/China !! - ESPECIALLY supposed 'audiophile' components - it is simply TOO EASY to fake them - and that's not just op-amps - it goes for everything - how many of those 'ELNA' caps do you really think are genuine Silmics?? - there will be whole factories set up to re-brand dirt cheap components into 'expensive' ones!

A genuine LM4562NA from Farnell - costs ..................... £2.83!!!!

[kabforks]

I've a spare that was removed when I fitted the Gator to my Caiman. I know that chip is good - pm me your address and I'll post it off to you.
Thank you! That is very kind of you. Much appreciated!


Ok I think that answers the question in my mind!! Steer cleer of that seller!!

I also have spare working op amps lying around if for whatever reason keith can't sort you out.

Butuz
Also, that's very kind of you too.


Please NEVER buy electronic components from Hong Kong/China !! - ESPECIALLY supposed 'audiophile' components - it is simply TOO EASY to fake them - and that's not just op-amps - it goes for everything - how many of those 'ELNA' caps do you really think are genuine Silmics?? - there will be whole factories set up to re-brand dirt cheap components into 'expensive' ones!

A genuine LM4562NA from Farnell - costs ..................... £2.83!!!!
Lesson learned :|.

[keiths]

Hi Daniel, Have also found another 4562NA op amp and have just tested that in my Caiman. Works fine. I'll post both op amps off to you later this week.

[Maximum]

Mark Grant also stocks these chips too.

http://markgrantcables.co.uk/shop/index.php?main_page=product_info&cPath=48_31&products_id=111

[StanleyB]

I have a couple spare. £2 each plus postage if anyone is interested. Just PM me and let me know how many you need.

[kabforks]

Hi Daniel, Have also found another 4562NA op amp and have just tested that in my Caiman. Works fine. I'll post both op amps off to you later this week.

I received the opamps right before the weekend... they work perfectly. And they are a noticeable improvement. Thank you very much :-).

This also means that the seller on eBay sells fake op-amps. Stay away people.