heat
Hi,
Very interesting remark about these muting transitors, Sandor. Thanks for the warning. I must say I did not chek that part of c-65. I must do it. Maybe it has a similar muting circuit as the preamp is not transparent enough to be named "natural sound" but I blamed that largely on the ancient op-amps.
Anyway, the way these muting transistors are configured they present very little loading to the output signal and they have to be that powerful as the output signal can be large. Of course they drain some power but not that much. In good Power Amps transformers are big enoug to never get really warm. May get warmish after some time but that is it.
Interesting that yamaha chose such a crazy muting solution and called the preamp (and the whole series) "natural sound". Although from manufacturer's perspective it is not so crazy as this circuit is a reliable method of muting. It's not likely to fail easily.
I do not know about c-80 and c-85 but c-65 transformer is tiny. Most of the space in the can is resin. Kills hum but stores heat like an oven tile from the old times and then this "oven" heats up the whole case and everything in it cooking caps. Properly sized transformer NEVER gets hot or even warm.
For some time I ran my c-65 for quite a while without the case.
The reason was that one day (in earlly days before mods only after polishing pot tracks and replacement of already cooked caps) my daughter called me at work saying that the sysyem worked ok but there was smoke coming out of the preamp. The problem was in the left channel of the phono equalizer. That's why she could play CDs, while that part of the phono section was burning. Of course I told her to swich off everything straight away.
I fixed the problem but a small burn out hole is left in the pcb as a reminder of a potential more dangerous fire. So I had to be sure that nothing else was going to burn again. Hence I operated it without the cover. The only sources of heat were the transformer and middle PS. After one or one and half hour of operation it was turning into a heater. The second source of heat, but much smaller, were power transistors in the phono PS. All the rest was cool or warmish. I kept touching all the components from time to time. That's how it is in c-65.
C-80 and c-85 have a small equalizer section instead of tone controls. Equilizer requires a litlle more power input than simple tone controls but probably not much more.
Anyway, the muting section deserves attention. It can be quite easily replaced by a simple one or bypassed by wire. To avoid thumps the preamp power cord could be plugged into the PA's socket (most PAs have power sockets for ancillary equipment to be plugged in) so when the PA is switched on the preamp is switched on as well but the PA's muting section prevents thumps to happen. Certainly it is the best solution from the signal quality perspective.
cheers,
Hi,
Very interesting remark about these muting transitors, Sandor. Thanks for the warning. I must say I did not chek that part of c-65. I must do it. Maybe it has a similar muting circuit as the preamp is not transparent enough to be named "natural sound" but I blamed that largely on the ancient op-amps.
Anyway, the way these muting transistors are configured they present very little loading to the output signal and they have to be that powerful as the output signal can be large. Of course they drain some power but not that much. In good Power Amps transformers are big enoug to never get really warm. May get warmish after some time but that is it.
Interesting that yamaha chose such a crazy muting solution and called the preamp (and the whole series) "natural sound". Although from manufacturer's perspective it is not so crazy as this circuit is a reliable method of muting. It's not likely to fail easily.
I do not know about c-80 and c-85 but c-65 transformer is tiny. Most of the space in the can is resin. Kills hum but stores heat like an oven tile from the old times and then this "oven" heats up the whole case and everything in it cooking caps. Properly sized transformer NEVER gets hot or even warm.
For some time I ran my c-65 for quite a while without the case.
The reason was that one day (in earlly days before mods only after polishing pot tracks and replacement of already cooked caps) my daughter called me at work saying that the sysyem worked ok but there was smoke coming out of the preamp. The problem was in the left channel of the phono equalizer. That's why she could play CDs, while that part of the phono section was burning. Of course I told her to swich off everything straight away.
I fixed the problem but a small burn out hole is left in the pcb as a reminder of a potential more dangerous fire. So I had to be sure that nothing else was going to burn again. Hence I operated it without the cover. The only sources of heat were the transformer and middle PS. After one or one and half hour of operation it was turning into a heater. The second source of heat, but much smaller, were power transistors in the phono PS. All the rest was cool or warmish. I kept touching all the components from time to time. That's how it is in c-65.
C-80 and c-85 have a small equalizer section instead of tone controls. Equilizer requires a litlle more power input than simple tone controls but probably not much more.
Anyway, the muting section deserves attention. It can be quite easily replaced by a simple one or bypassed by wire. To avoid thumps the preamp power cord could be plugged into the PA's socket (most PAs have power sockets for ancillary equipment to be plugged in) so when the PA is switched on the preamp is switched on as well but the PA's muting section prevents thumps to happen. Certainly it is the best solution from the signal quality perspective.
cheers,
c- series output muting
Hi,
During the weekend I analysed the c-65 circuit in mor detail. Unfortunately c-65 has exactly the same protection circuit on both line and headphones outputs. The headphone oputput does not bother me.
The line output can be either shortened or a small relay based circuit added. I'll post such a circuit this or next week. It needs +12V PS, a darlington and two relays (or one dual) plus a few diodes, resistors and a cap of course. The PS can be built on two 1n4004 diodes, 7812 regulator, a few caps while AC can be taken from the transformer. PS can be located close to the transformer and relay circuit on the output.
These 2.2 and 4.7 resistors between rectifier bridges and main filtering caps are special parts and I suspect these may be inductive to remove spikes. I think I will not touch them. I'll order this week a few more adaptors from Cimaron Technologies (old BD) and replace all op-amps when these arrive. I'll also build one relay circuit to test it and then decide whether to use it in yamaha or simply short circuit the line output.
cheers,
Hi,
During the weekend I analysed the c-65 circuit in mor detail. Unfortunately c-65 has exactly the same protection circuit on both line and headphones outputs. The headphone oputput does not bother me.
The line output can be either shortened or a small relay based circuit added. I'll post such a circuit this or next week. It needs +12V PS, a darlington and two relays (or one dual) plus a few diodes, resistors and a cap of course. The PS can be built on two 1n4004 diodes, 7812 regulator, a few caps while AC can be taken from the transformer. PS can be located close to the transformer and relay circuit on the output.
These 2.2 and 4.7 resistors between rectifier bridges and main filtering caps are special parts and I suspect these may be inductive to remove spikes. I think I will not touch them. I'll order this week a few more adaptors from Cimaron Technologies (old BD) and replace all op-amps when these arrive. I'll also build one relay circuit to test it and then decide whether to use it in yamaha or simply short circuit the line output.
cheers,
yamaha mods
Hi,
Chris, these are not really high level mods. They may have the appearance of such but they are not. I hope to built and test a relay design modified by me and if it works it may be used in yamaha. I redesigned it to use in a new preamp I designed a few years ago.
I bought yamaha to fill in the time gap needed to have my new preamp finished. Yamaha was to replace my previous preamp built from a modified kit, which started to introduce hum when tone control was in. As it was a very simple design and its volume control never really worked properly I decided to replace it rather to spend a hundred or more (as I would have to buy programable remote control) on fixing it. The replacement was expected to work fine for a few years before I had the time to finish my new preamp.
Unfortunately, I bought c-65 with coroded pots and switches and eight expired caps either swallen as if somebody baked them in an oven or as light as a feather as they were completely dry. I had to dismantle the preamp to remove pots and switches.
The guy who sold me that preamp sounded honest and apparently spent $150 on fixing it. So I sent these pots and one switch to his technician who was paid these $150 for doing some spraying. Initially he was willing to find replacements for these pots but of course he didn't.
Luckily polishing the tracks solved pots problem but the main volume and loudness control pots are not fixable or replacable. Once they are gone the preamp is gone - unless one redesigns that section and rebuilds with currently available pots or 24 position switches.
The guy who sold me the preamp refunded me for fixing the basic problems so that is how I got involved in this unexpected project and looks it's going to cost me more than the preamp I designed.
The only things I like about c-65 are its discrete phono section and two tape inputs/outputs. Also tracks are wide so a few repairs and mods are posiible. I was also curious about yamaha's variable loudness but when I saw that it is permanent and the way it has been designed I lost most of the exitement.
Nevertheless, this preamp may be modified to the point it can rival most commercial preamps on the market using op-amps and pots (not discrete switches) at a fraction of their costs - as long as the existing pots keep working well.
Replacement of transformetrs will cost about A$45, all caps cost me somewhat less than A$100 (without those initial four caps I had to remove after a few months as they were two or three mm too long and cost me A$100 but that was my fault).
Replacing of all op-amps with sockets and BD adaptors (U$45 alone including mailing cost) will cost about US$125 - $150 depending on op-amps used. With the commercially bought opa627au it would be much more. Each of these cost almost US$20 from Mouser or DigiKey but I bought ten of these on EBay for US$10 each but I do not think I'll be using these here. Maybe only four of these at most. All the other will be not so expensive opa2132P/PAs and cheap LM4562s and/or op275gps. So the total modification costs should be about A$275, which is about US$235.
The realy section with its PS is pretty cheap but not necessary as a bit of wire or jumper resistor can do the job for almost nothing. One only has to fit a power socket on the main PA (if not already there) and one of these can be removed from the preamp so only two thick enough wires have to be soldered to connect the PA power socket with the new preamp AC feeding socket. And in fact, apart from being the cheapest, it may be the best solution for domestic purposes. Adding a relay circuit on line outputs will keep the preamp as a stand alone bit of equipment.
cheers,
Hi,
Chris, these are not really high level mods. They may have the appearance of such but they are not. I hope to built and test a relay design modified by me and if it works it may be used in yamaha. I redesigned it to use in a new preamp I designed a few years ago.
I bought yamaha to fill in the time gap needed to have my new preamp finished. Yamaha was to replace my previous preamp built from a modified kit, which started to introduce hum when tone control was in. As it was a very simple design and its volume control never really worked properly I decided to replace it rather to spend a hundred or more (as I would have to buy programable remote control) on fixing it. The replacement was expected to work fine for a few years before I had the time to finish my new preamp.
Unfortunately, I bought c-65 with coroded pots and switches and eight expired caps either swallen as if somebody baked them in an oven or as light as a feather as they were completely dry. I had to dismantle the preamp to remove pots and switches.
The guy who sold me that preamp sounded honest and apparently spent $150 on fixing it. So I sent these pots and one switch to his technician who was paid these $150 for doing some spraying. Initially he was willing to find replacements for these pots but of course he didn't.
Luckily polishing the tracks solved pots problem but the main volume and loudness control pots are not fixable or replacable. Once they are gone the preamp is gone - unless one redesigns that section and rebuilds with currently available pots or 24 position switches.
The guy who sold me the preamp refunded me for fixing the basic problems so that is how I got involved in this unexpected project and looks it's going to cost me more than the preamp I designed.
The only things I like about c-65 are its discrete phono section and two tape inputs/outputs. Also tracks are wide so a few repairs and mods are posiible. I was also curious about yamaha's variable loudness but when I saw that it is permanent and the way it has been designed I lost most of the exitement.
Nevertheless, this preamp may be modified to the point it can rival most commercial preamps on the market using op-amps and pots (not discrete switches) at a fraction of their costs - as long as the existing pots keep working well.
Replacement of transformetrs will cost about A$45, all caps cost me somewhat less than A$100 (without those initial four caps I had to remove after a few months as they were two or three mm too long and cost me A$100 but that was my fault).
Replacing of all op-amps with sockets and BD adaptors (U$45 alone including mailing cost) will cost about US$125 - $150 depending on op-amps used. With the commercially bought opa627au it would be much more. Each of these cost almost US$20 from Mouser or DigiKey but I bought ten of these on EBay for US$10 each but I do not think I'll be using these here. Maybe only four of these at most. All the other will be not so expensive opa2132P/PAs and cheap LM4562s and/or op275gps. So the total modification costs should be about A$275, which is about US$235.
The realy section with its PS is pretty cheap but not necessary as a bit of wire or jumper resistor can do the job for almost nothing. One only has to fit a power socket on the main PA (if not already there) and one of these can be removed from the preamp so only two thick enough wires have to be soldered to connect the PA power socket with the new preamp AC feeding socket. And in fact, apart from being the cheapest, it may be the best solution for domestic purposes. Adding a relay circuit on line outputs will keep the preamp as a stand alone bit of equipment.
cheers,
output relay
Hi,
The attached is a simple output relay circuit I mentioned before. I have not yet tested it as Altronics shop here in Perth ran out of 1A dual relays I intended to use. The schematic shows two single relays but with dual relay there will be one coil and one diode (1n4448 preferably) instead of two. The dual relay from Altronics has is 1A silver palladium contact expected to survive 200,000 operations. Once I get the relay I'll build a test circuit and test it.
It was to be used in my preamp I designed a few years ago. Quite a simple one but with tone, gain control and direct swich - only volume and balance pots in the circuit. The volume was to be 25k TKD log pot from Michael percy Audio plus 6 position stereo swich from him as well.
The RIAA phono was to be based on ad797an and opa627bp and the preamp section on two opa626aps operated in class A. The output capacitance was to be formed by two 10uF/100V polypropylenes in parallel show on the sketch.
cheers,
Hi,
The attached is a simple output relay circuit I mentioned before. I have not yet tested it as Altronics shop here in Perth ran out of 1A dual relays I intended to use. The schematic shows two single relays but with dual relay there will be one coil and one diode (1n4448 preferably) instead of two. The dual relay from Altronics has is 1A silver palladium contact expected to survive 200,000 operations. Once I get the relay I'll build a test circuit and test it.
It was to be used in my preamp I designed a few years ago. Quite a simple one but with tone, gain control and direct swich - only volume and balance pots in the circuit. The volume was to be 25k TKD log pot from Michael percy Audio plus 6 position stereo swich from him as well.
The RIAA phono was to be based on ad797an and opa627bp and the preamp section on two opa626aps operated in class A. The output capacitance was to be formed by two 10uF/100V polypropylenes in parallel show on the sketch.
cheers,
Yamaha Beryllium Tweeters
Hi all,
Looking for a little advice regarding sourcing a replacement tweeter for a pair of Yamaha NS2000's I picked up recently. Several memebers and XEAGLEKEEPER in particular have obviously been through this in the past and I wondered if they, or anyone, might volunteer some advice ?
The original Yamaha part number is JA0526A. Obvioulsy long gone and unavailable now, but are the tweeters used in the NS1000 series and the "X", "M" and "MM" models the same, or close enough to use ?
I've had vaarying opinions when I ask, some say yes, as its unlikely Yamaha made a different Beryllium Tweeter for each model. Others point to slightly different impedances and say they must be different.
Physically, the only difference I can pick is that the 2000 model faceplate is bigger. This can easily be swapped over from what I can see.
Being located in Australia doesn't make it any easier, but I'm determined not to let this one beat me - the speakers are too good to give up on !
Thanks in advance
Scott
Hi all,
Looking for a little advice regarding sourcing a replacement tweeter for a pair of Yamaha NS2000's I picked up recently. Several memebers and XEAGLEKEEPER in particular have obviously been through this in the past and I wondered if they, or anyone, might volunteer some advice ?
The original Yamaha part number is JA0526A. Obvioulsy long gone and unavailable now, but are the tweeters used in the NS1000 series and the "X", "M" and "MM" models the same, or close enough to use ?
I've had vaarying opinions when I ask, some say yes, as its unlikely Yamaha made a different Beryllium Tweeter for each model. Others point to slightly different impedances and say they must be different.
Physically, the only difference I can pick is that the 2000 model faceplate is bigger. This can easily be swapped over from what I can see.
Being located in Australia doesn't make it any easier, but I'm determined not to let this one beat me - the speakers are too good to give up on !
Thanks in advance
Scott
yamaha tweeters,
Hi Scott,
This thread is about yamaha c- series preamplifiers. You have to initialize a new theread in speaker section.
The only thing I can say is that you need to get technical data (best Small and Thiele parameters) of the tweeter in question plus data on the remaining drivers and crosovers used.
You do not have to use exactly the same tweeter. The new tweeter must match the remainder of the system. Preferably its nominal impedance should be the same (actual impedances vary around the nominal one) and its sensitivity.
Sensitivity is the most important here - that is sound level generated by the tweeter (measured at 1m or 2 m from the source along the speaker axis) when 2.83V signal (eg. about 3kHz for a tweeter) is applied. This must match the sensitivity of the system or be up to +1dB higher. At lest, it cannot be lower than that of the system midrange. If it is higher you may use resistor divider but it's better to avoid it and find a tweeter of matching sensitivity.
There are many good tweeters on the market and many of these are much better than the one you want to replace. You might even go for a ribbon tweeter if your midrange is linear past 6kHz. But probably you would have to rebuild the crossover in that case.
cheers,
Hi Scott,
This thread is about yamaha c- series preamplifiers. You have to initialize a new theread in speaker section.
The only thing I can say is that you need to get technical data (best Small and Thiele parameters) of the tweeter in question plus data on the remaining drivers and crosovers used.
You do not have to use exactly the same tweeter. The new tweeter must match the remainder of the system. Preferably its nominal impedance should be the same (actual impedances vary around the nominal one) and its sensitivity.
Sensitivity is the most important here - that is sound level generated by the tweeter (measured at 1m or 2 m from the source along the speaker axis) when 2.83V signal (eg. about 3kHz for a tweeter) is applied. This must match the sensitivity of the system or be up to +1dB higher. At lest, it cannot be lower than that of the system midrange. If it is higher you may use resistor divider but it's better to avoid it and find a tweeter of matching sensitivity.
There are many good tweeters on the market and many of these are much better than the one you want to replace. You might even go for a ribbon tweeter if your midrange is linear past 6kHz. But probably you would have to rebuild the crossover in that case.
cheers,
Thanks for the answer, but there no way I'd fit an aftermarket tweeter to speakers of this value, NS1000's yes, but not the NS2000's sorry. They are simply way to valuable to modify.
Also, I note that the original thread contained info on these speakers, but I'll innitiate a new thread as you suggest.
Thanks again
Scott
Also, I note that the original thread contained info on these speakers, but I'll innitiate a new thread as you suggest.
Thanks again
Scott
yamaha tweeter
Hi Scott,
You are wrong. I've just checked data on yamaha ns2000. It's 6ohm nominal 90dB system with upper crossover frequency of 6kHz, which means it could be matched with a good ribbon - but it's not that I'm advocating ribbons. They have their merits and weaknesses. The best ribbons are great but many are really poor. And then durability of membrane may be a problem.
In ns2000 both midrange and tweeters have beryllium domes. If you want super upgrade you may go for accuton diamond tweeter D2 20/6, which has a sensitivity of 89.5dB. Close enough. Diamond tweeters are really great but too expensive for most.
But anyway, initiate a new thread and do not be afraid of non-yamaha upgrades. Berllium tweeters were produced by a few companies in the past. Probably some are still in production. Accuton makes quite good ceramic tweeters at much lowr price but they are not so good as their diamons and a few other tweeters. B&W also makes diamond tweeters for their flag systems.
Anyway, good luck
cheers,
Hi Scott,
You are wrong. I've just checked data on yamaha ns2000. It's 6ohm nominal 90dB system with upper crossover frequency of 6kHz, which means it could be matched with a good ribbon - but it's not that I'm advocating ribbons. They have their merits and weaknesses. The best ribbons are great but many are really poor. And then durability of membrane may be a problem.
In ns2000 both midrange and tweeters have beryllium domes. If you want super upgrade you may go for accuton diamond tweeter D2 20/6, which has a sensitivity of 89.5dB. Close enough. Diamond tweeters are really great but too expensive for most.
But anyway, initiate a new thread and do not be afraid of non-yamaha upgrades. Berllium tweeters were produced by a few companies in the past. Probably some are still in production. Accuton makes quite good ceramic tweeters at much lowr price but they are not so good as their diamons and a few other tweeters. B&W also makes diamond tweeters for their flag systems.
Anyway, good luck
cheers,
tweeters
One more thing I forgot to mention,
Take a look at Madison and Solen sites and a few other driver vendors including Scandinavian and French. Madison sells accuton diamond D2 for $2600 each. A bit too expensive for me but maybe one day I'll became crazy enough to try them.
At the moment I'm looking for some very good midrange to suit my system. It has to be 8 ohm, about 90dB sensitive and must fit the existing cut out and stand at least 120W rms. The cut out may be somewhat enlarged but by no more than 10 to 15mm.
cheers,
One more thing I forgot to mention,
Take a look at Madison and Solen sites and a few other driver vendors including Scandinavian and French. Madison sells accuton diamond D2 for $2600 each. A bit too expensive for me but maybe one day I'll became crazy enough to try them.
At the moment I'm looking for some very good midrange to suit my system. It has to be 8 ohm, about 90dB sensitive and must fit the existing cut out and stand at least 120W rms. The cut out may be somewhat enlarged but by no more than 10 to 15mm.
cheers,
op-amp upgrade in yamaha c-65
Hi,
This weekend I desoldered all audio path op-amps, except for the headphone one, soldered in 9 pin sockets and installed new op-amps from the variety I had at hand. As I haven't got yet LM4562s I installed temporarily LM833s and opa2134s in the equalizer section.
The tone control is based on op275s entirely as I have many of these from times when they were new and have to use them somewhere. All the other op-amps are opa2132Ps.
I still do not know which op-amp to use in the headphone section. I'll replace it in a few weeks and at the same time add a number of poly caps to help a few electros, not yet having such assistance, do their job properly. Most likely I'll also replace the transforer with two 30VA toroids as mentioned before and will wire the preamp's output after removing these two couples of muting transistors. I'll keep those in the headphone section, however.
A few words of warning: the service manual (c-65 one) has a couple of errors in drawings eg some op-amps are shown with wrong pin numbers and on page 13 (!!!) the diagram showing internal pin connections of the following ICs: njm2041s, njm4558s and njm4556s-a has an error as well. Internal op-amp "B" pin 6 should be input plus and pin 7 should be input minus not the other way round.
All these otherwise standard eight pin op-amps were manufactured at yamaha's request as nine pin ones with pin 1 and pin 9 being internally connected - they both act as V plus (PS connection). In a standard 8 pin dual op-amp pin 8 is V plus.
On PCBs it is either pin 1 or pin 9 connected to V plus. If pin 1 is V plus it has to be wired to pin 9 as all replacement 8 pin dual op-amps on BD adaptors have to be inserted with adaptor pin 8 going into pin 9 on the PCB. Otherwise you know what is going to happen.
Yamaha, in some cases uses that additional pin one linkeage to pin nine (as the last pin in 8 pin any standard op-amp is V plus) as a jumper connecting other circuit parts to V plus. Crazy inconvenience when it comes to servicing these preamps.
On Saturday I also got missing parts for the relay so I'll build it and test it this week. If it works fine it can be used in preaps and alike but I do not think I'll use it in c-65.
Now, the sonic result (all electros were replaced almost a year ago). My wife, who is neither a musical genius nor a musical freak, said on hearing it - without being asked for any comments! - that the sonic stage has widen up and is more lively. And that's my impression as well. I'd say it's more accurate but that is memory based imnpression. No A-B testig as I have only one c-65 and no testing against a live performance - which is the only true fidelity test.
cheers,
Hi,
This weekend I desoldered all audio path op-amps, except for the headphone one, soldered in 9 pin sockets and installed new op-amps from the variety I had at hand. As I haven't got yet LM4562s I installed temporarily LM833s and opa2134s in the equalizer section.
The tone control is based on op275s entirely as I have many of these from times when they were new and have to use them somewhere. All the other op-amps are opa2132Ps.
I still do not know which op-amp to use in the headphone section. I'll replace it in a few weeks and at the same time add a number of poly caps to help a few electros, not yet having such assistance, do their job properly. Most likely I'll also replace the transforer with two 30VA toroids as mentioned before and will wire the preamp's output after removing these two couples of muting transistors. I'll keep those in the headphone section, however.
A few words of warning: the service manual (c-65 one) has a couple of errors in drawings eg some op-amps are shown with wrong pin numbers and on page 13 (!!!) the diagram showing internal pin connections of the following ICs: njm2041s, njm4558s and njm4556s-a has an error as well. Internal op-amp "B" pin 6 should be input plus and pin 7 should be input minus not the other way round.
All these otherwise standard eight pin op-amps were manufactured at yamaha's request as nine pin ones with pin 1 and pin 9 being internally connected - they both act as V plus (PS connection). In a standard 8 pin dual op-amp pin 8 is V plus.
On PCBs it is either pin 1 or pin 9 connected to V plus. If pin 1 is V plus it has to be wired to pin 9 as all replacement 8 pin dual op-amps on BD adaptors have to be inserted with adaptor pin 8 going into pin 9 on the PCB. Otherwise you know what is going to happen.
Yamaha, in some cases uses that additional pin one linkeage to pin nine (as the last pin in 8 pin any standard op-amp is V plus) as a jumper connecting other circuit parts to V plus. Crazy inconvenience when it comes to servicing these preamps.
On Saturday I also got missing parts for the relay so I'll build it and test it this week. If it works fine it can be used in preaps and alike but I do not think I'll use it in c-65.
Now, the sonic result (all electros were replaced almost a year ago). My wife, who is neither a musical genius nor a musical freak, said on hearing it - without being asked for any comments! - that the sonic stage has widen up and is more lively. And that's my impression as well. I'd say it's more accurate but that is memory based imnpression. No A-B testig as I have only one c-65 and no testing against a live performance - which is the only true fidelity test.
cheers,
c-65 photo
Hi Chris,
I took a photo with intention to show it here but even zipped it is almost 0.5Mb so it will not fit here and I have no program to make it smaller. If you give me your email I can send it directly to you.
This weekend I'll replace the headphone op-amp (njm4556S-A) with a socket and put in temporarily opa2604 or something else.
If I really wanted to use headphones more often with c-65 then I'd have to make a miniboard with say opa2132P followed by two BUF634 (one per channel) plus a couple of resistors and caps. I have already designed it (and have parts) for use in my reel-to-reeel pioneer rt-909 where it is really needed as it drives both the output and headphones.
On the other hand I have a good headphone amp with two outputs in my active crossover meant for the new system so most likely I'll try to find a dual op-amp good enough to drive headphones. Njm4556S-A is a dedicated headphone driver but of ancient quality.
cheers,
Hi Chris,
I took a photo with intention to show it here but even zipped it is almost 0.5Mb so it will not fit here and I have no program to make it smaller. If you give me your email I can send it directly to you.
This weekend I'll replace the headphone op-amp (njm4556S-A) with a socket and put in temporarily opa2604 or something else.
If I really wanted to use headphones more often with c-65 then I'd have to make a miniboard with say opa2132P followed by two BUF634 (one per channel) plus a couple of resistors and caps. I have already designed it (and have parts) for use in my reel-to-reeel pioneer rt-909 where it is really needed as it drives both the output and headphones.
On the other hand I have a good headphone amp with two outputs in my active crossover meant for the new system so most likely I'll try to find a dual op-amp good enough to drive headphones. Njm4556S-A is a dedicated headphone driver but of ancient quality.
cheers,
interesting!
i just bought a clean Yamaha C-80. box, manual, warranty card, etc.
i haven't received it yet, but i would be interested in the schematic for future repairs and mods.
i don't necessarily want to go as nuts as some of you guys, but what would be a basic rebuild/mod assuming everything works as is?
I'm assuming filter caps but what are the modern equivalents of the existing op-amps? which are the most critical to update if i wanted to go that route?
when i put Burr-Brown OPA134 in my 1984 Quad 405-2, the improvement in sound was amazing!
i'm currently using McIntosh MC-60 tube amps and yamaha NS-1000M speakers for reference.
thanks,
Robby
i just bought a clean Yamaha C-80. box, manual, warranty card, etc.
i haven't received it yet, but i would be interested in the schematic for future repairs and mods.
i don't necessarily want to go as nuts as some of you guys, but what would be a basic rebuild/mod assuming everything works as is?
I'm assuming filter caps but what are the modern equivalents of the existing op-amps? which are the most critical to update if i wanted to go that route?
when i put Burr-Brown OPA134 in my 1984 Quad 405-2, the improvement in sound was amazing!
i'm currently using McIntosh MC-60 tube amps and yamaha NS-1000M speakers for reference.
thanks,
Robby
yamaha c series preamp mods
Hi Robby,
If your yamaha has not relly been used or seldom used you may choose to replace a few crucial celectros in audio path with upgrades. Next parallell all audio path and PS and associated electros with polypropylenes of required values, replace PS diodes with fast soft recovery ones, desolder all the audio path op-amps, solder in sockets, get BD adaptors and choose modern op-amps to your liking.
My choices for the equalizer section are lm4562s as these are low noise and fast enoughfor that purpose and not very expensive. In tone control section I have currently op275s but ultimately I'll use opa2132Ps (or opa2132PA as a minimum).
If you want to go up from opa2132P then the best upgrade would be expensive opa627au. In all other circuits I use opa2132P except for the headphone section. I haven't yet decided which op-amp to use there. The top solution would be opa2132P plus two buf634 buffers or something similar.
If you really love your yamaha c-80 then you can use opa627au everywhere except for the equalizer section, where lm4562s are good enough. Keep in mind that variable loudness op-amp is always in the audio path so it must get the same grade op-amps as gain stages outside the equalizer section.
The only other things to do are reducing heat generted by PS (eg new toroids and a few holes in the top cover in the right places), deoxidising and lubricating your pots plus some upgrade of the output muting section.
You may go for a good relay circuit or just wire across CEs of these two pairs of transistors on the output after these have been gently removed - just in case you liked them back. Wiring the output is the simplest thing to do.
cheers,
Hi Robby,
If your yamaha has not relly been used or seldom used you may choose to replace a few crucial celectros in audio path with upgrades. Next parallell all audio path and PS and associated electros with polypropylenes of required values, replace PS diodes with fast soft recovery ones, desolder all the audio path op-amps, solder in sockets, get BD adaptors and choose modern op-amps to your liking.
My choices for the equalizer section are lm4562s as these are low noise and fast enoughfor that purpose and not very expensive. In tone control section I have currently op275s but ultimately I'll use opa2132Ps (or opa2132PA as a minimum).
If you want to go up from opa2132P then the best upgrade would be expensive opa627au. In all other circuits I use opa2132P except for the headphone section. I haven't yet decided which op-amp to use there. The top solution would be opa2132P plus two buf634 buffers or something similar.
If you really love your yamaha c-80 then you can use opa627au everywhere except for the equalizer section, where lm4562s are good enough. Keep in mind that variable loudness op-amp is always in the audio path so it must get the same grade op-amps as gain stages outside the equalizer section.
The only other things to do are reducing heat generted by PS (eg new toroids and a few holes in the top cover in the right places), deoxidising and lubricating your pots plus some upgrade of the output muting section.
You may go for a good relay circuit or just wire across CEs of these two pairs of transistors on the output after these have been gently removed - just in case you liked them back. Wiring the output is the simplest thing to do.
cheers,
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