Hi,
Just bought a Marantz PM-54 II. Sound is very pleasant and I cleaned up the inside and the pots.
There seems to be a IC in the Phono stage. Would the advanced members of the forum take a look to let me know if this is a dual opamp as I have in reserve several discrete opamps I could install, hopefully further improving the phono stage quality.
Here is the manual: http://www.vintageshifi.com/reperto...=Marantz-PM-54-II-PM-64-II-Service-Manual.pdf
Many thanks for any advice.
Best regards.
Just bought a Marantz PM-54 II. Sound is very pleasant and I cleaned up the inside and the pots.
There seems to be a IC in the Phono stage. Would the advanced members of the forum take a look to let me know if this is a dual opamp as I have in reserve several discrete opamps I could install, hopefully further improving the phono stage quality.
Here is the manual: http://www.vintageshifi.com/reperto...=Marantz-PM-54-II-PM-64-II-Service-Manual.pdf
Many thanks for any advice.
Best regards.
Hi lecentaur,
Can you actually read the number off the IC? Some of those JRC op amps were not bad. As for it being of the 4558 era, almost every op amp out there until recently were of that family, save the parts from Linear Technology and some Analog Devices parts, followed by National Semiconductor's current lineup.
Anyway, don't get too excited about it. The J-Fet diff pair in front take the stress off of the dual op amp. Replacing that op amp might make an audible improvement, but then again, maybe not. That isn't a horrible phono amp section.
If you aren't really good at de-soldering and soldering, leave it alone. It's plenty easy to cause damage, especially if you aren't using a proper controlled temperature soldering station.
-Chris
Can you actually read the number off the IC? Some of those JRC op amps were not bad. As for it being of the 4558 era, almost every op amp out there until recently were of that family, save the parts from Linear Technology and some Analog Devices parts, followed by National Semiconductor's current lineup.
Anyway, don't get too excited about it. The J-Fet diff pair in front take the stress off of the dual op amp. Replacing that op amp might make an audible improvement, but then again, maybe not. That isn't a horrible phono amp section.
If you aren't really good at de-soldering and soldering, leave it alone. It's plenty easy to cause damage, especially if you aren't using a proper controlled temperature soldering station.
-Chris
Thank you Jon for the confirmation, I will search it out from here.
Thank you Chris, I do have a desoldering iron with vaccum pump, the if it is a standard size dip 8 socket I should do it without harming board or component then be able to try out with different opamps.
Until now, there has been clear improvement using these Burson Audio opamps, the only time I did not have success was on a chinese DAC where I did not know how to adapt the voltage of the socket...
Now that I know it is a dual opamp, I will check the size and read the number off it.
Thanks
Thank you Chris, I do have a desoldering iron with vaccum pump, the if it is a standard size dip 8 socket I should do it without harming board or component then be able to try out with different opamps.
Until now, there has been clear improvement using these Burson Audio opamps, the only time I did not have success was on a chinese DAC where I did not know how to adapt the voltage of the socket...
Now that I know it is a dual opamp, I will check the size and read the number off it.
Thanks
Last edited:
Difference maybe, less sure about the improvement part. The one Burson opamp that Samuel Groner tested proved to be an Audio-gd OPA-Earth with rather pedestrian performance, especially at normal voltages (+/- 15 V).
The stock opamp is given as NJM2041DD. A hot-rod 4558 apparently, with lower noise, faster slew rate and higher bandwidth. There'd be a no-brainer upgrade in the NJM2043D, which at same current consumption is twice as fast and a bit leess noisy (well, almost a no-brainer anyway, as rail decoupling may need to be improved here - it's a part with 1st-order compensation and 14 MHz BW after all, and 470µ caps aren't exactly RF kings). Its higher input bias current would be of no consequence here. I'm not sure how well a 2nd-order compensated part like the NJM2068 works when coupled with an external input stage, and likewise, how well-behaved a 5532 would be. OPA2227 may be worth a shot, too.
Sockets are good for experimenting, they're definitely worsening layout parasitics though. Keeping a scope handy seems a good idea in any case.
Many thanks for this detailed info.
I am now a bit worried that I might degrade it as the chip does not seem to be a "discount" one. But I do have many dual opamps to swap, I guess it should be worthwhile.
One question, what Scope available to order online would fit these kind of needs and descent functionalities ?
Thanks
I am now a bit worried that I might degrade it as the chip does not seem to be a "discount" one. But I do have many dual opamps to swap, I guess it should be worthwhile.
One question, what Scope available to order online would fit these kind of needs and descent functionalities ?
Thanks
OK, I jumped and did it.
Luckily the unsoldering of the existing IC was not a big issue as I could nearly reach all pins from behind with the un-soldering pump.
Once the dip socket was installed I almost blew it 😀 by installing the IC the wrong way around but turned the amp off as soon as I saw some smoke on R429 (on the right of the picture).
Anyway, hoping I have not created an issue further on, I first put back correctly the original opamp and it worked (I think left channel took 10 seconds to go back on).
Then started rolling opamps. Tried the OPA627 (two singles mounted on adapter) and it was definitely less tiny than the original one. Then tried the Burson opamp and indeed as Dennis from Burson Audio support had indeed indicated it did not run because of power requirement.
Finally I had one ClassD Danish discrete opamp in my draw and it was a revelation. Sound was warm and full. We will be able to make more tests this weekend with the speakers (Mission M35i) as my daughter will finish her exams and get her combined birthday/exams gift 😉
Probably the opamp selection will also depend on the catridge used (Grado in this case), I think it is good to have the choice to easily try different combinations of cartridge/opamp.
Thank you all for your support. This forum is absolutely fantastic and I look forward to sharing more project and learning from the experts.
Best wishes.
Here is a picture of the board after the upgrade:
Luckily the unsoldering of the existing IC was not a big issue as I could nearly reach all pins from behind with the un-soldering pump.
Once the dip socket was installed I almost blew it 😀 by installing the IC the wrong way around but turned the amp off as soon as I saw some smoke on R429 (on the right of the picture).
Anyway, hoping I have not created an issue further on, I first put back correctly the original opamp and it worked (I think left channel took 10 seconds to go back on).
Then started rolling opamps. Tried the OPA627 (two singles mounted on adapter) and it was definitely less tiny than the original one. Then tried the Burson opamp and indeed as Dennis from Burson Audio support had indeed indicated it did not run because of power requirement.
Finally I had one ClassD Danish discrete opamp in my draw and it was a revelation. Sound was warm and full. We will be able to make more tests this weekend with the speakers (Mission M35i) as my daughter will finish her exams and get her combined birthday/exams gift 😉
Probably the opamp selection will also depend on the catridge used (Grado in this case), I think it is good to have the choice to easily try different combinations of cartridge/opamp.
Thank you all for your support. This forum is absolutely fantastic and I look forward to sharing more project and learning from the experts.
Best wishes.
Here is a picture of the board after the upgrade:
Last edited:
Hi lecentaur,
With the J-Fet diff pair in front of your "op-amp", it will not matter what cartridge you use. The J-Fets shield the rest of the circuit.
-Chris
With the J-Fet diff pair in front of your "op-amp", it will not matter what cartridge you use. The J-Fets shield the rest of the circuit.
-Chris
Hello Chris,
Thank you for your follow-up. I tried again this time with high grade headphones and can confirm that the NewClassD discrete opamp does have a fuller sound than any other of the ICs I have handy.
The IC nearest to it is the OPA627.
Now I do realise that without blind testing it can be subjective, just sharing my perception at present time.
Best and thank you for your support.
Thank you for your follow-up. I tried again this time with high grade headphones and can confirm that the NewClassD discrete opamp does have a fuller sound than any other of the ICs I have handy.
The IC nearest to it is the OPA627.
Now I do realise that without blind testing it can be subjective, just sharing my perception at present time.
Best and thank you for your support.
Just wanted to share the result of this project.
We installed the Lenco L75 on a marble platter which is fixed on bier cans ! Yes, had to find four fun legs, cushioned by silicon and very tough carpets as in the picture.
The result with the Missions M35i is absolutely incredible. The Marantz is a very honorable Amp and indeed the phono stage is very decent.
Actually and now we can laugh about it, the result must have been earth shaking as the entire foldable double bed collapsed, luckily nobody got hurt but what made us laugh is that despite this heavy furniture crashing on the floor, the isolation was so good that Eric Clapton's "let it go" did not jump 😀
Here is the picture, before the bed collapsed, but it will be fixed by tomorrow 😉 and I promise I wont be drinking those beer cans
Thanks again for the support.
We installed the Lenco L75 on a marble platter which is fixed on bier cans ! Yes, had to find four fun legs, cushioned by silicon and very tough carpets as in the picture.
The result with the Missions M35i is absolutely incredible. The Marantz is a very honorable Amp and indeed the phono stage is very decent.
Actually and now we can laugh about it, the result must have been earth shaking as the entire foldable double bed collapsed, luckily nobody got hurt but what made us laugh is that despite this heavy furniture crashing on the floor, the isolation was so good that Eric Clapton's "let it go" did not jump 😀
Here is the picture, before the bed collapsed, but it will be fixed by tomorrow 😉 and I promise I wont be drinking those beer cans
Thanks again for the support.
Last edited:
Hi lecentaur,
Excellent news!
Now, go in and solder your op amp of choice directly in. Sockets are not something I would use in my own equipment without a good reason. Sockets increase capacitance between pins and some will have contact problems after a number of years. Time passes quickly for audio equipment.
-Chris
Excellent news!
Now, go in and solder your op amp of choice directly in. Sockets are not something I would use in my own equipment without a good reason. Sockets increase capacitance between pins and some will have contact problems after a number of years. Time passes quickly for audio equipment.
-Chris
- Status
- Not open for further replies.