Hello everyone 🙂
i would like to upgrade the oamp from my sony str-k7000. i'm thinking to use the lm4562 or opa2604 over the NJM4565 (have a lot of them in the board) . any Suggestions?
service manual:
Sony STR-K7000, Service Manual, Repair Schematics
i would like to upgrade the oamp from my sony str-k7000. i'm thinking to use the lm4562 or opa2604 over the NJM4565 (have a lot of them in the board) . any Suggestions?
service manual:
Sony STR-K7000, Service Manual, Repair Schematics
Well faster opamps might need extra decoupling caps added to the board for stability, something to watch out for.
Mark, thanks for the info. i need to study the circuit to do it too. i think the opa 2604 will be the best option for me (sound) , i don't know how it will sounds yet because i don't find any mod or upgrade for these apmlifier. i'm thinking to recap the sony str-k7000 too , it is second hand reciver. i will import the material to do it. 😎
Why the stupid OPA2604? The thing isn't particularly good at anything, including load driving. The only potential advantage is being useful at higher than usual supply voltages (which it also needs to perform decently), but then you quickly run into the dual's power dissipation limits. At one point it had a faster than average slew rate (even considering that FET input slew rate generally isn't as "valuable" as BJT input slew rate by a factor of 2 or 3) which made it a common choice in DAC output stages, but that was in the early '90s.
I would never support swapping out opamps willy-nilly. Look at the circuit (supply voltages, associated impedances), look at the layout (power trace routing, decoupling), look at signal levels, see what kind of limits to power budget you might have, make an informed decision from there.
It does seem a bit skimpy to find loads of 4565s in a 2006 vintage receiver... I would have thought that 4580s would have been more common by then.
Let's see what we've got...
IC402, sub pre-out amp, gain of 2 with 10k + 10k... nope, not worth it.
IC691, overload detect amp... not in the signal path.
IC2000, auto cal mic preamp... not likely to be worse than a cheap little electret capsule. I might suggest a little 10 µF capacitor in parallel to R2018, C2018 for a cleaner electret bias voltage.
That pretty much leaves only a handful of ICs at the DAC output. Hmm. Looks like an active lowpass. Reasonably high impedance (at low freqs it's basically a follower presented with a source impedance in excess of 13k). It's probably a good thing that they've got an opamp with low input bias current there. Something better may be out there but with all the stuff preceding it I wouldn't be holding my breath.
Supplies are +/- 7 V. Not a good match for OPA2604 for sure. Regs are a pair of TA7807S / TA79007S... I didn't even know they made 7 V parts. The datasheet indicates fairly low output noise for a 3-terminal job, the negative one appears to be even quieter than the positive one.
Looks like the whole input selector + preamp section is inside this BD3451KS chip, apparently a Rohm OEM deal with no datasheet or anything out there. This also permits switching between an all-analog signal path and one with the DSP section in place (ADC PCM1800 - almost a decade old by then but surprisingly still available brand new now -, DSP CXD9718BQ, DAC PCM1609).
Basically, if you're bypassing the whole DSP stuff, there is absolutely nothing to be gained. If you're not, it's still very dubious (I mean, the PCM1800 has an SNR/DNR spec of 95 dB and THD+N of -88 dB, so not the last word in performance at all).
In a way, it's a typical Sony. They've always liked to rely on integration to minimize complexity, generally making things more reliable in the process. The downside is that if things get as barebones as this unit, there isn't much tweaking potential left.
I would never support swapping out opamps willy-nilly. Look at the circuit (supply voltages, associated impedances), look at the layout (power trace routing, decoupling), look at signal levels, see what kind of limits to power budget you might have, make an informed decision from there.
It does seem a bit skimpy to find loads of 4565s in a 2006 vintage receiver... I would have thought that 4580s would have been more common by then.
Let's see what we've got...
IC402, sub pre-out amp, gain of 2 with 10k + 10k... nope, not worth it.
IC691, overload detect amp... not in the signal path.
IC2000, auto cal mic preamp... not likely to be worse than a cheap little electret capsule. I might suggest a little 10 µF capacitor in parallel to R2018, C2018 for a cleaner electret bias voltage.
That pretty much leaves only a handful of ICs at the DAC output. Hmm. Looks like an active lowpass. Reasonably high impedance (at low freqs it's basically a follower presented with a source impedance in excess of 13k). It's probably a good thing that they've got an opamp with low input bias current there. Something better may be out there but with all the stuff preceding it I wouldn't be holding my breath.
Supplies are +/- 7 V. Not a good match for OPA2604 for sure. Regs are a pair of TA7807S / TA79007S... I didn't even know they made 7 V parts. The datasheet indicates fairly low output noise for a 3-terminal job, the negative one appears to be even quieter than the positive one.
Looks like the whole input selector + preamp section is inside this BD3451KS chip, apparently a Rohm OEM deal with no datasheet or anything out there. This also permits switching between an all-analog signal path and one with the DSP section in place (ADC PCM1800 - almost a decade old by then but surprisingly still available brand new now -, DSP CXD9718BQ, DAC PCM1609).
Basically, if you're bypassing the whole DSP stuff, there is absolutely nothing to be gained. If you're not, it's still very dubious (I mean, the PCM1800 has an SNR/DNR spec of 95 dB and THD+N of -88 dB, so not the last word in performance at all).
In a way, it's a typical Sony. They've always liked to rely on integration to minimize complexity, generally making things more reliable in the process. The downside is that if things get as barebones as this unit, there isn't much tweaking potential left.
Last edited:
sgrossklass, Thank you so much for your answer . reading your message I can understand why there are no documents to upgrade these recivers on the web. thank you very much for all your explanation, it was of great value for me to have access to all this technical information, so I have to prepare myself for a planning to change the equipment for another one with better sound quality. I believe then that it will not even be worth recapping with better quality capacitors because the sound difference at the end should not be relevant to the point of expense and effort. I will do your 10 µF capacitor tip in parallel between R2018 and C2018 for a clean voltage bias. 🙂