Mod your Beresford 7520

[HighFidelityGuy]

Ah I was wondering why I couldn't find any info on the LME4970HA, it's actually the LM4562HA, how odd.

They're £20.30 from Farnell, so that ebay source is nearly 50% cheaper. Nice find!

[kalozois100]

if you already have a LM4562 in your 7510 6/4 Mod 21 part 2 is it worth changing it for a THS4032?

This is definately a question i would like answered too as i also have the above mods you mention in the 7510..........yeah is it worth it or not? The LM4562MA already seems a very good performer.

[StanleyB]

This is definately a question i would like answered too as i also have the above mods you mention in the 7510..........yeah is it worth it or not? The LM4562MA already seems a very good performer.

The THS4032 is far more of a performer in the TC-7520. I wouldn't advise carrying out any more surgery on the PCB through a repeat removal of the TC-7510 opamp. Disaster possibilities such as track damage are higher than 66.6%. On a fresh PCB you stand a better chance of success.

[HighFidelityGuy]

I've just ordered a pair of LME4970HA's and some of the adapter boards needed for the THS4032. I'll be ordering the THS4032 form Farnell at a later date along with some other bits I need for other projects I'm working on. I'll let you all know what I think to them.

[sponge]

Oh no - I seem to have a problem.

Last night the TC-7520 headphone amp with THS4032's was playing fine, so I replaced the cover and left the unit playing with a looped CD into my K701's.

This morning when I had a listen, I hear a VERY faint "crackle" on quiet passages - Only when music is playing and not noticeable on louder passages. It's not the source as the same thing happens when playing the same track via CD (optical) or Squeezebox (coax).

I suspect a bit of instability with the THS4032's - But which one?

Perhaps Stan can help here - I am aware the 4032 is not unity gain stable so maybe this cannot be fixed if one of the opamps is acting as a buffer. Pity really as I love the THS4032 sound signature.

Have any of you guys trying the THS4032 noticed anything similar?

Ken

[kalozois100]

The THS4032 is far more of a performer in the TC-7520. I wouldn't advise carrying out any more surgery on the PCB through a repeat removal of the TC-7510 opamp. Disaster possibilities such as track damage are higher than 66.6%. On a fresh PCB you stand a better chance of success.

Statistics always get my attention Stan!! - and i hadn't realised the risk for repeated opamp changes although i am kicking myself I didn't install an adapter for opamp rolling for the 7510 at the time of changing the opamp . Still it sounds very good as it is so i am thankfull the mods went well with no side effects. one suggestion for 7520 owners is how much i like the audio signature of the black gate caps in the mods for the 7510 that the LM4562MA drive. Is this feasible for the 7520 aswell??

[HighFidelityGuy]

Oh no - I seem to have a problem.

Last night the TC-7520 headphone amp with THS4032's was playing fine, so I replaced the cover and left the unit playing with a looped CD into my K701's.

This morning when I had a listen, I hear a VERY faint "crackle" on quiet passages - Only when music is playing and not noticeable on louder passages. It's not the source as the same thing happens when playing the same track via CD (optical) or Squeezebox (coax).

I suspect a bit of instability with the THS4032's - But which one?

Perhaps Stan can help here - I am aware the 4032 is not unity gain stable so maybe this cannot be fixed if one of the opamps is acting as a buffer. Pity really as I love the THS4032 sound signature.

Have any of you guys trying the THS4032 noticed anything similar?

Ken

Hmm, that's a bit worrying. Perhaps they are over heating? Would it be possible for you to check how hot they are and report back?

[sponge]

Hmm, that's a bit worrying. Perhaps they are over heating? Would it be possible for you to check how hot they are and report back?

Well, I have the cover off the TC-7520 at the moment and the chips are well within their temp range - Only warm to the touch and the unit has been powered up for quite a while.

This is so annoying as the sound (to my ears) is superb - It drives the K701's effortlessly.

Ken

[Covenant]

Could you swap back the old op-amps just to make sure its not something else?

[HighFidelityGuy]

Thanks for the update.

I've just been comparing the THS4032 with the original NE5532 and I noticed that the NE5532 needs up to +/- 22V while the THS4032 only needs up to +/- 16V. I don't know if this has anything to do with it. I guess it depends on what voltage the 7520 is giving the chip. I guess Stan is the best person to answer this. Any idea what's causing this Stan?