Rotel 855 PICS, dac & opamp question for newbie...
Im new at the audio DIY game guys, so thanks for any advice. I just landed this off ebay for under $100 and it sounds pretty decent and build quality is great. I am ready to tinker.
It appears the dac (tda1541a) & opamps (mc34082p) are on sockets. What are some suggested replacements & where can they be ordered?
Also, any other easy mods for this unit?
Can anyone show how to turn the laser up a bit? It is skipping some on lightly scratched cds.
Im new at the audio DIY game guys, so thanks for any advice. I just landed this off ebay for under $100 and it sounds pretty decent and build quality is great. I am ready to tinker.
It appears the dac (tda1541a) & opamps (mc34082p) are on sockets. What are some suggested replacements & where can they be ordered?
Also, any other easy mods for this unit?
Can anyone show how to turn the laser up a bit? It is skipping some on lightly scratched cds.
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Hello Psonic,
I just modified my Rotel RCD855 few weeks ago and sounds very good now. the rotel need to be dissambled to remove PBC board and the whole mecs, from there you can:
replace all elecs capacitors (panasonic FC recommeded), change all diodes with stokky (11DQ10),
replace opamps (my one are 2 NE5532s I changed them for OPA2604s), change 14 decoupling cap around TDA1541 for something like Revox Rifa MMY serie and finally put a low jitter clock and PSU for it.
Hope this will help.
I just modified my Rotel RCD855 few weeks ago and sounds very good now. the rotel need to be dissambled to remove PBC board and the whole mecs, from there you can:
replace all elecs capacitors (panasonic FC recommeded), change all diodes with stokky (11DQ10),
replace opamps (my one are 2 NE5532s I changed them for OPA2604s), change 14 decoupling cap around TDA1541 for something like Revox Rifa MMY serie and finally put a low jitter clock and PSU for it.
Hope this will help.
Hi,
Some time ago I modded this player for my friend.
BB2134 works better than BB2604 in it. With 2604 the sound is very sharp,not that smooth and silk.A little fatique to listen to (I don't know why).The MMY Rifa is quite weak for decoupling.I got much better performance with pink Philips polypropylene caps.1uF/63V.They are 3 times the price of Rifa at my local store (about 0,25$) ,but are much better.
Bartek
Some time ago I modded this player for my friend.
BB2134 works better than BB2604 in it. With 2604 the sound is very sharp,not that smooth and silk.A little fatique to listen to (I don't know why).The MMY Rifa is quite weak for decoupling.I got much better performance with pink Philips polypropylene caps.1uF/63V.They are 3 times the price of Rifa at my local store (about 0,25$) ,but are much better.
Bartek
Hi
A few years backs I done several mods to the Rotel RCD965 apart from op-amps and the Trichord clock,there was a FREE mod that had good sonic effect.
Removing the muting transistors these were located close to the output phono sockets.I did not notice any clicks when stopping or starting playback,but you could hear noise on a scan.
A few years backs I done several mods to the Rotel RCD965 apart from op-amps and the Trichord clock,there was a FREE mod that had good sonic effect.
Removing the muting transistors these were located close to the output phono sockets.I did not notice any clicks when stopping or starting playback,but you could hear noise on a scan.
They are there to prevent clicks and pops in speakers when powering the player off and on while the power amp is on (volume control up).
I remove them in every player I have.
B.
Greetings,
Can the muting transistors be seen in this photo, if so can you point them out? Excuse my electronics ignorance, but will I need to bridge where they were or just pull it and done?
BTW, I ordered opa2134 & opa2604 samples (free, yay!) along with a few from analog devices to try out...
Can the muting transistors be seen in this photo, if so can you point them out? Excuse my electronics ignorance, but will I need to bridge where they were or just pull it and done?
BTW, I ordered opa2134 & opa2604 samples (free, yay!) along with a few from analog devices to try out...
I have the ROTEL 965 BX it is very similar to the 855 can I remove my muting transistor too?
Have you the schematics of this player?
Thanks
Have you the schematics of this player?
Thanks
You can remove them, they are the small black half moon transistors (3 prong) closest to the output rca's. there should be 4 of them just like shown here. They can be desoldered or clipped off. I do not have the map of the 965 though.
Regards,
Stephan
Regards,
Stephan
Thank you psonic I have just desoldered it,I'm realy surprisely,great improvement to quality sound,this is the better tweaking I never done.More details and clean,and much real sound it's difficult to say in word.
This tweaking is on the same level as XO2 clock by Lcaudio,wich I have installed 1 year ago.
This tweaking is on the same level as XO2 clock by Lcaudio,wich I have installed 1 year ago.
Hi psonic, do you mean that you do not need to short the connections after removing the muting transistors?
Hi Psonic,
Interesting! I never knew that, I learn something new everyday. Out of curosity, why should this make such a difference?
Interesting! I never knew that, I learn something new everyday. Out of curosity, why should this make such a difference?
The muting transistors were perhaps bipolar and only serves as a short if the muting is on. The thing i heard was that they presented an unlinear capacitive load when muting was off.
I have also experienced a great improvement when removing my muting transistors.
I have also experienced a great improvement when removing my muting transistors.
Wow, where have I been. There's a wealth of info here on the Rotel RCD-855 - my first real CDP back in 1989/90. LOL
Ok I think it's time for me to get cracking. I managed to get a new lens unit - the Philips CDM 4-19 sometime back. But after installing the unit the CDP still skips on occation. I think it might be the quartz oscillator - 11.2896 MHz.
Before I start modding this unit (with a new audiofile clock) I would like to know where I can get the quartz oscillater? Once I have ensured that the unit is working well (ie no skipping problems). I intend to do a clock mod. I intend to use the Net Audio clocks see: http://www.net-audio.co.uk/cdupgradesindx.html
Anyone has any comments about these clocks?
Also, anyone with a schematic please email it to me - thanking you in advance.
Ok I think it's time for me to get cracking. I managed to get a new lens unit - the Philips CDM 4-19 sometime back. But after installing the unit the CDP still skips on occation. I think it might be the quartz oscillator - 11.2896 MHz.
Before I start modding this unit (with a new audiofile clock) I would like to know where I can get the quartz oscillater? Once I have ensured that the unit is working well (ie no skipping problems). I intend to do a clock mod. I intend to use the Net Audio clocks see: http://www.net-audio.co.uk/cdupgradesindx.html
Anyone has any comments about these clocks?
Also, anyone with a schematic please email it to me - thanking you in advance.
Hi Rameish,
where did you get your laser replacement parts in SG? I have a 12 yr old RCD 955 AX (with TDA1541 modified into NOS and semi discrete I/V), I think it's a very similar unit. Haven't checked the mechanism number yet. I am about to revamp it now and I am looking for recommendations, and also for sources for parts.
Interesting that the skipping didn't diappear completely. Did you change the whole mechanism or just the laser? I heard on this forum that a drop of gear box oil on the ball bearings of the mechanism should help. Unless it's new then it can't be due to that one I guess.
As for other actions to revamp:
- replacement of electrolytics is a given
- decoupling of the TDA1541: I have seen Sanyo Oscons recommended for that - any experiences/recommendations?
- clock upgrade: worth it if used in NOS mode and on such an old player? if so, which one?
- someone mentioned grounding the crystal's can to improve jitter performance - to which ground?
- separate PSU/X-F for clock / for output stage: worth it? if so, where to connect the grounds?
Recommendations and other tips appreciated to save it from oblivion. It's basically OK but has troubles reading some CD's and especially, RW's. I am now using a cheapo Philips DVD/CD and even with my MSB Link DAC it doesn't cut it in soundstage and air... so I'd like to reconsider the Rotel.
where did you get your laser replacement parts in SG? I have a 12 yr old RCD 955 AX (with TDA1541 modified into NOS and semi discrete I/V), I think it's a very similar unit. Haven't checked the mechanism number yet. I am about to revamp it now and I am looking for recommendations, and also for sources for parts.
Interesting that the skipping didn't diappear completely. Did you change the whole mechanism or just the laser? I heard on this forum that a drop of gear box oil on the ball bearings of the mechanism should help. Unless it's new then it can't be due to that one I guess.
As for other actions to revamp:
- replacement of electrolytics is a given
- decoupling of the TDA1541: I have seen Sanyo Oscons recommended for that - any experiences/recommendations?
- clock upgrade: worth it if used in NOS mode and on such an old player? if so, which one?
- someone mentioned grounding the crystal's can to improve jitter performance - to which ground?
- separate PSU/X-F for clock / for output stage: worth it? if so, where to connect the grounds?
Recommendations and other tips appreciated to save it from oblivion. It's basically OK but has troubles reading some CD's and especially, RW's. I am now using a cheapo Philips DVD/CD and even with my MSB Link DAC it doesn't cut it in soundstage and air... so I'd like to reconsider the Rotel.
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