I'm a very happy long time owner of a CA-2000 along with it's partner BA-2000 after aquiring them while stationed in Japan in the late 70s. They've served me well and I hope to use your valuable info here to try and keep them in good shape for the future.
Awesome insights as always. Love the chat and details. It brings to light some things we may miss or just not be aware of. Thank you as always for another great vid. I'm catching up on a few that were put out during a busy spell here, but they are not to be missed !
Hi Tony, Thanks again for the awesome video on capacitors and DATS V3. The V3 bought based on your video arrived on Thursday and it's a great machine. I'm glad you confirmed my point about swapping capacitors with different voltages - I've always said max one value. I'm really looking forward to the comparison video of the amplifiers. Nice day 🙂Tom
Thank you for the thorough explanation of why things work the way they work, with the schematic. I would love to see more of this. This is very helpfull. 👌
Excellent video - I watched both related with capacitors / Sansui and opened my eyes: I'm currently restoring a Denon tape deck (I'm just a reborn electronics hobbyist) - main mechanical problems solved, but there are problems on recording with muffled sound and less volume on one channel. I've been preparing a list of capacitors and was about to replace most of them for polyester ones (except the PS ones and space restricting) - now I'm looking deeply in the schematics to check where does / does not make sense. From your teachings I'll keep / replace the BP electrolytic ones, as well as others EL's that have some film cap in parallel - and great hint about the caps on the headphones amp stage - EL's they'll be. Time to change my draft order :) None of the transistors you mentioned is present in the deck - in the Rec head path after the opamp (BA15218) there are 2 MOSFET 2SK381 followed by 4 all different so called digital transistors - DTC144ES, DTC124XS, DTA143XS, DTC124ES. Not willing to take much of your time, from your experience, might any of these be the reason for the muffled recording (assuming there's no problems at the head which I only briefly cleaned - not deeply cleaned/demagnetized (yet). Tks
This might sound stupid but have you tried swapping left and right head wires to see if problem moves to other channel? It might save you a lot of time troubleshooting.
The change from 2.2 uF to 4.7 uF must have been due to a change in the output impedance, otherwise, it should have stayed the same to keep the low end frequency response the same. About those resistors, the only thing I can think of is that they must have had an issue with the protective case failing, allowing moisture /air to affect the resistive element itself. I've never heard of metal films doing that, but I'm open to learning something new.
2:04 Regarding the voltage difference in capacitors, most ESR tests are done at the "industry standaard 100Khz" test frequency, but is that kind of test (100Khz) not intended when dealing with capacitors for switching powersupplies applications? The audible frequency range for humans is between 20Hz and 20Khz on paper, but in reality, in practice only young people will hear up to + 12Khz, where most majority of the people only can hear up to 12Khz and the older we get, the lower this top value becomes.There is no doubt that there will be a difference in the characteristic of the amplifier when using different value of voltage (and corresponding ESR value) of the capacitor , but if you can't hear the difference, then it is only for power/energy consumption reasons interesting. It would be interesting if you could do a test at multiple lower frequencies more in the audible audio range, maybe a test at 1Khz, 5Khz and 10Khz and a amplifier with one channel the very high voltage versions of a specific capacitor(s), and on the other channel the more suitable voltage level of capacitor(s) and then a scope connected to see the difference in output / distortion and clipping level etc... Grtz
I was gonna say those resistors are fusing ones(Sansui put quite alot of those in their designs) but after checking one of their service manuals i saw they are non-inflamable.I know fusing resistors go really bad out of spec and sometimes go open but i didn't know it's same case with non-inflamable ones. They both need to be replaced with same wattage rating cause their job is to protect circuit.They probably won't, cause transistor is fastest fuse 😆,but they might save something else.
RE: capacitors: ignoring all parameters (size etc) but just focusin on voltage, does it really affect the performance of the device IF using caps with higher voltage (hence higher ESR) if its ers is still withing tolerance or working limit of the capacitor? this probably will matter in digital circuits but will this matter in analog circuits?
Good question! Capacitors don't really know if a signal is digital or analog. They only react to changes in voltage. In an ideal capacitor, that change in voltage will lag the change in current by 90 degrees. ESR, ESL and leakage will all affect this more or less, dependent upon frequency. A well-designed circuit will take these factors into consideration and will choose components and values to compensate for this. When you change the capacitor with one that has different characteristics, it will change how that part of the circuit reacts to changes in frequency. This can be perceived as sounding "better" or "worse", depending on each person's hearing or preference. This is why the debate continues and will continue forever. Sound quality is just as much a matter of opinion as it is science. Thanks for the comment!
I'm no Tony, but first thing that comes to mind is that the PNPs of the day were less noisy than the NPNs, which is crucial for the application. The choice is also dictated by the next stage of amplification, which normally has the other type of transistors than the diff. pair. Biasing is also a consideration.
Thanks for helping out! I would add one more thought. Depending on the polarity of the circuit, you may want to choose one over the other. This will keep the signal from being inverted, or even will invert it on purpose as the circuitry down the line may require. ;)
I'm a very happy long time owner of a CA-2000 along with it's partner BA-2000 after aquiring them while stationed in Japan in the late 70s.
They've served me well and I hope to use your valuable info here to try and keep them in good shape for the future.
Tony it's always a great pleasure to see your videos, congratulations
Awesome insights as always. Love the chat and details. It brings to light some things we may miss or just not be aware of. Thank you as always for another great vid. I'm catching up on a few that were put out during a busy spell here, but they are not to be missed !
Hi Tony. I am envious, A real quality pre amp and a great job restoring / servicing these. Thanks for all the hard work. Mike.
Good one! Thanks for the effort you put in for the viewers.
Hi Tony, Thanks again for the awesome video on capacitors and DATS V3. The V3 bought based on your video arrived on Thursday and it's a great machine.
I'm glad you confirmed my point about swapping capacitors with different voltages - I've always said max one value.
I'm really looking forward to the comparison video of the amplifiers.
Nice day 🙂Tom
thank you for making this video
Thank you for the thorough explanation of why things work the way they work, with the schematic. I would love to see more of this. This is very helpfull. 👌
Excellent video - I watched both related with capacitors / Sansui and opened my eyes: I'm currently restoring a Denon tape deck (I'm just a reborn electronics hobbyist) - main mechanical problems solved, but there are problems on recording with muffled sound and less volume on one channel. I've been preparing a list of capacitors and was about to replace most of them for polyester ones (except the PS ones and space restricting) - now I'm looking deeply in the schematics to check where does / does not make sense. From your teachings I'll keep / replace the BP electrolytic ones, as well as others EL's that have some film cap in parallel - and great hint about the caps on the headphones amp stage - EL's they'll be. Time to change my draft order :)
None of the transistors you mentioned is present in the deck - in the Rec head path after the opamp (BA15218) there are 2 MOSFET 2SK381 followed by 4 all different so called digital transistors - DTC144ES, DTC124XS, DTA143XS, DTC124ES. Not willing to take much of your time, from your experience, might any of these be the reason for the muffled recording (assuming there's no problems at the head which I only briefly cleaned - not deeply cleaned/demagnetized (yet). Tks
This might sound stupid but have you tried swapping left and right head wires to see if problem moves to other channel? It might save you a lot of time troubleshooting.
The change from 2.2 uF to 4.7 uF must have been due to a change in the output impedance, otherwise, it should have stayed the same to keep the low end frequency response the same.
About those resistors, the only thing I can think of is that they must have had an issue with the protective case failing, allowing moisture /air to affect the resistive element itself. I've never heard of metal films doing that, but I'm open to learning something new.
2:04 Regarding the voltage difference in capacitors, most ESR tests are done at the "industry standaard 100Khz" test frequency,
but is that kind of test (100Khz) not intended when dealing with capacitors for switching powersupplies applications?
The audible frequency range for humans is between 20Hz and 20Khz on paper, but in reality, in practice only young people will hear up to + 12Khz, where most majority of the people only can hear up to 12Khz and the older we get, the lower this top value becomes.There is no doubt that there will be a difference in the characteristic of the amplifier when using different value of voltage (and corresponding ESR value) of the capacitor , but if you can't hear the difference, then it is only for power/energy consumption reasons interesting.
It would be interesting if you could do a test at multiple lower frequencies more in the audible audio range, maybe a test at 1Khz, 5Khz and 10Khz and a amplifier with one channel the very high voltage versions of a specific capacitor(s), and on the other channel the more suitable voltage level of capacitor(s) and then a scope connected to see the difference in output / distortion and clipping level etc... Grtz
I was gonna say those resistors are fusing ones(Sansui put quite alot of those in their designs) but after checking one of their service manuals i saw they are non-inflamable.I know fusing resistors go really bad out of spec and sometimes go open but i didn't know it's same case with non-inflamable ones. They both need to be replaced with same wattage rating cause their job is to protect circuit.They probably won't, cause transistor is fastest fuse 😆,but they might save something else.
It never ceases to amaze me at how well a component can protect a fuse from blowing ;)
Pretty sure the "funny " colored resistors are fusible type. At least they are in other sansui amps.
RE: capacitors: ignoring all parameters (size etc) but just focusin on voltage, does it really affect the performance of the device IF using caps with higher voltage (hence higher ESR) if its ers is still withing tolerance or working limit of the capacitor? this probably will matter in digital circuits but will this matter in analog circuits?
Good question! Capacitors don't really know if a signal is digital or analog. They only react to changes in voltage. In an ideal capacitor, that change in voltage will lag the change in current by 90 degrees. ESR, ESL and leakage will all affect this more or less, dependent upon frequency. A well-designed circuit will take these factors into consideration and will choose components and values to compensate for this. When you change the capacitor with one that has different characteristics, it will change how that part of the circuit reacts to changes in frequency. This can be perceived as sounding "better" or "worse", depending on each person's hearing or preference. This is why the debate continues and will continue forever. Sound quality is just as much a matter of opinion as it is science. Thanks for the comment!
Could you explain why diff pair is PNP and not NPN??
I'm no Tony, but first thing that comes to mind is that the PNPs of the day were less noisy than the NPNs, which is crucial for the application. The choice is also dictated by the next stage of amplification, which normally has the other type of transistors than the diff. pair. Biasing is also a consideration.
Thanks for helping out! I would add one more thought. Depending on the polarity of the circuit, you may want to choose one over the other. This will keep the signal from being inverted, or even will invert it on purpose as the circuitry down the line may require. ;)
30:45 - Track down the manufacturer of those Rs! (if that's possible at this point :( )
If you can't take anymore projects why do you advertise!
I didn't realize that i was advertising???
He isn't.....
Hmmm, so much angst in that exclamation point (that should be a ? mark). Boggles the mind. Anyway, thanks for everything Tony.