Hi all 
I'm new here, but have read much that has been written about modifications to the output stage to improve the so-so sound quality, so i must appologise for bringing this subject up once more.
Being short of money at the moment i decided to buy some LM4562's, replacing the two devices feeding the outputs. straight away the difference was quite breath taking, more open,with more front to back depth.
I did notice it was brighter, which i think makes it sound even more open than it really is. As some have found, the sound can seem overly bright on some poorly produced material, but given a well produced disc, well it's hard to believe it's the same machine.
Has anyone managed to ovecome the apparent brightness of this IC? I'm not sure i can live with this sound for good, so if there's no known cure, i guess i'll have to look at the more expensive alternatives.
Which brings me to a question. I live in the UK. Is there a good, reliable, well priced priced supplier here?
I guess i have to consider opa627's on brown Dog's unless there is a more reasonably priced alternative now?
Also, i see so many mentions of the I/V chip, what is he requirments for this chip, and is there a better alternative to it, which shows real improvements in sound? I guess the same goes for the filter IC as well.
I see so many people say the sound is "improved" by removing the muting transistors, but i've not seen one mention of how it is improved. Pease don't say it makes it brighter
🙄
Any help would be greatly appreciated
OD
I'm new here, but have read much that has been written about modifications to the output stage to improve the so-so sound quality, so i must appologise for bringing this subject up once more.
Being short of money at the moment i decided to buy some LM4562's, replacing the two devices feeding the outputs. straight away the difference was quite breath taking, more open,with more front to back depth.
I did notice it was brighter, which i think makes it sound even more open than it really is. As some have found, the sound can seem overly bright on some poorly produced material, but given a well produced disc, well it's hard to believe it's the same machine.
Has anyone managed to ovecome the apparent brightness of this IC? I'm not sure i can live with this sound for good, so if there's no known cure, i guess i'll have to look at the more expensive alternatives.
Which brings me to a question. I live in the UK. Is there a good, reliable, well priced priced supplier here?
I guess i have to consider opa627's on brown Dog's unless there is a more reasonably priced alternative now?
Also, i see so many mentions of the I/V chip, what is he requirments for this chip, and is there a better alternative to it, which shows real improvements in sound? I guess the same goes for the filter IC as well.
I see so many people say the sound is "improved" by removing the muting transistors, but i've not seen one mention of how it is improved. Pease don't say it makes it brighter
🙄Any help would be greatly appreciated
OD
You are used with a more muted sound. Any opamp faster than what you have already it will sound even "brighter" (not very much, 4562 is a good opamp). And the muting trasitors will have the same effect (altough I don't belive it too much, I didn't try it myself).
Did you leave it playing enough time? Eventually your brain will adjust 🙂
Did you leave it playing enough time? Eventually your brain will adjust 🙂
Thanks for the reply. yea, i ran it playing a disc on repeat for about a day, will continue with it for a while. When you tried yours, what did IC's did you use for the I/V and filter?
OD
OD
Had enough so sorted the "sound" issue
I tried my best to try and accept the Sound i was experiencing as right and normal, but i'm afraid i just got tired of it. So this morning i had a play, and i believe the bright, harsh sound the LM4562 is capable of is very curable.
All i did was to solder a 0.1uf ceramic cap directly on to pins 4 & 8 as described elsewhere. I also noticed on the circuit diagram that the supply lines close to the IC's only have 0.1uf smd ceramics on them.So i also added a 10uf cap on each suplly line, soldering one lead directly to the pin underneath with the other leg on the earth point of the smd cap.
I used the same CD's i had used before, and the difference was like night and day. The brightness had totally gone! The only problem now is the ears had gotten so used to his over bright sound it's going to take a while for them to get used to something like normal.
I also noticed the "clinical, cold" feeling to music had been replaced with something with feeling. In fact it sounds like a different chip!
Checking the rest of the circuit i noticed that the other chips in the audio section only have the same 0.1uf smd caps as decoupling so i need to get some more to complete the job.
It's also a shame to see ceramic caps being used in the audio line, mainly C341,342 C371,372 C303,304 so these will be replaced as well. Not sure if they will alter the sound but ceramics don't belong there!
Would appreciate any comments and/or feedback.
As a side note, i replaced the NJM2068 in the RIAA section of my Marantz PM66KI, and the first thing i heard was that steely trebble, so i'l be doing the same to that as well as replcing the caps in the feedback network to something a little better.
Right, back to the listening.... 🙂
OD
I tried my best to try and accept the Sound i was experiencing as right and normal, but i'm afraid i just got tired of it. So this morning i had a play, and i believe the bright, harsh sound the LM4562 is capable of is very curable.
All i did was to solder a 0.1uf ceramic cap directly on to pins 4 & 8 as described elsewhere. I also noticed on the circuit diagram that the supply lines close to the IC's only have 0.1uf smd ceramics on them.So i also added a 10uf cap on each suplly line, soldering one lead directly to the pin underneath with the other leg on the earth point of the smd cap.
I used the same CD's i had used before, and the difference was like night and day. The brightness had totally gone! The only problem now is the ears had gotten so used to his over bright sound it's going to take a while for them to get used to something like normal.
I also noticed the "clinical, cold" feeling to music had been replaced with something with feeling. In fact it sounds like a different chip!
Checking the rest of the circuit i noticed that the other chips in the audio section only have the same 0.1uf smd caps as decoupling so i need to get some more to complete the job.
It's also a shame to see ceramic caps being used in the audio line, mainly C341,342 C371,372 C303,304 so these will be replaced as well. Not sure if they will alter the sound but ceramics don't belong there!
Would appreciate any comments and/or feedback.
As a side note, i replaced the NJM2068 in the RIAA section of my Marantz PM66KI, and the first thing i heard was that steely trebble, so i'l be doing the same to that as well as replcing the caps in the feedback network to something a little better.
Right, back to the listening.... 🙂
OD
That correct, the decoupling caps for the faster OpAmp's need to be revised at every OpAmp replacement - exectly like you did. manufacturer should have done a better job there, but hey...
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