Hello all
My Marantz and most of my CD players have the LM4562 which I find is great. I have a Technics MASH cd player with the SMDs type of opamps needed. I love details clarity, soundstage - listen to rock classical and vocals. I got free shipping with Element14 till 29th of this month ! 😀
I was thinking of going out of my comfort safe zone - LM series to try a OPA
OPA1602?
OPA1642 ?
OPA 1612 ?expensive
any of these would be a better over say a LME49720 /LM4562
Thank you
Kind Regards
Sam
My Marantz and most of my CD players have the LM4562 which I find is great. I have a Technics MASH cd player with the SMDs type of opamps needed. I love details clarity, soundstage - listen to rock classical and vocals. I got free shipping with Element14 till 29th of this month ! 😀
I was thinking of going out of my comfort safe zone - LM series to try a OPA
OPA1602?
OPA1642 ?
OPA 1612 ?expensive
any of these would be a better over say a LME49720 /LM4562
Thank you
Kind Regards
Sam
Thinking exactly the same, hear something different from the OPA2132 I'm used to, I decided to buy some units of the OP1612.
I tested for a few hours and is quite similar with the NE5532.
*Maybe with a SNR slightly better.
Then I got the suspicion that might be fakes. 😕
If anyone can help .. the following image:
I tested for a few hours and is quite similar with the NE5532.
*Maybe with a SNR slightly better.
Then I got the suspicion that might be fakes. 😕
If anyone can help .. the following image:
I have heard good things about the 1612, is used in some Fiio products as well.
My favorite OPA would be the 627, available for more reasonable prices on that popular auction site, from the right seller.
My favorite OPA would be the 627, available for more reasonable prices on that popular auction site, from the right seller.
Hi Felipe, so you liked the 1612. I dont know if they are fake but i buy my parts from Element14, Mouser and places like that. I would take detail photos and send to TI industries, so they can see if its fake.
Hi Phase, Thanks. The 1612 is rather expensive at element14 $15 dollars, but I only need one I think with this Technics MASH player. Did you mean ebay , i am scared to buy from there eletronic ICS. The OPA727 is single
Hi Abraxalito, I have the schmatic, and i am guessing is the last opamp before the output which is the important one to change. I would upgrade power supply with good caps , change bps to wima or use muse ES. Below is the schmatic
An externally hosted image should be here but it was not working when we last tested it.
The schematic is very helpful thanks. Looking at it its clear that your DAC chip has internal opamps (its voltage-out), these are most likely to be the weakest link in the chain such that they'll limit the improvement you get from upgrading downstream chips.
In my experience the way to get the best performance (subjectively) from any opamp is to give it the lightest possible load to drive. Hence buffering the DAC itself would most likely pay the highest dividends here.
In my experience the way to get the best performance (subjectively) from any opamp is to give it the lightest possible load to drive. Hence buffering the DAC itself would most likely pay the highest dividends here.
Thanks Abraxalito,
I was thinking it was the IC891 I would change. Its a MASH Technics player. IC802 is the LM88 directly after the DAC. What is the best to do with buffering the DAC?
I have already removed muting transistors on the output and blutack the clock. Just have to get SilmicII around DAC, some in the power supply with Nichicons, bipolars on the IC891 use ES muse or Wima depends on the Wimas cost
I was thinking it was the IC891 I would change. Its a MASH Technics player. IC802 is the LM88 directly after the DAC. What is the best to do with buffering the DAC?
I have already removed muting transistors on the output and blutack the clock. Just have to get SilmicII around DAC, some in the power supply with Nichicons, bipolars on the IC891 use ES muse or Wima depends on the Wimas cost
For buffering a digital IC where the outputs are going to be fairly contaminated with out-of-band noise, I prefer to use discrete transistors. An emitter follower discrete transistor with its emitter loaded by a two-transistor current source works well. The current source magnitude is chosen to exceed the peak required output current by at least 30%. Since the DAC's outputs are symmetrical the primary source of harmonic distortion of an EF will cancel out as its 2nd-order.
Feel free to largely ignore Abrax's "advice" and handwringing on PSU wrt opamps. That said, make sure there's some sort of >100 nF x7r sitting on each supply pin to ground (and closely terminated to the opamp pin).
As far as opamps -- 1602 and 4562 are going to behave awfully similar. 1642 is nice in that it's a jfet input with very very good linearity which might mask less-than-ideal circuit design.
As far as opamps -- 1602 and 4562 are going to behave awfully similar. 1642 is nice in that it's a jfet input with very very good linearity which might mask less-than-ideal circuit design.
MASH covers a few different number of bits in the output - the DAC output could just be switches
if 802 is LM833, its bjt input isn't suited to the circuit filter/feedback impedances - really should be a jfet type
OPA1642 looks good on paper, better when you read the chatter from TI engineer on the project
I would worry that there simply isn't enough low pass filtering on the board for the MASH output - even if it were a few bits multibit D-S as the latter MASH
if 802 is LM833, its bjt input isn't suited to the circuit filter/feedback impedances - really should be a jfet type
OPA1642 looks good on paper, better when you read the chatter from TI engineer on the project
I would worry that there simply isn't enough low pass filtering on the board for the MASH output - even if it were a few bits multibit D-S as the latter MASH
@MaccAu - you might be interested to note Derf's behavioural patterns on DIYA, he does display a particular tendency to follow me around threads and attempt to negate what I'm sharing, making it into a personality thing rather than a matter of engineering.
'Bad engineering' is entirely of your own creation old chap.
Again the alleged 'magic' is entirely provided by your own mind. Ditto 'guru'-like. Unless you have any evidence in support of either?
Thanks Abraxalito, i am fairly confused which opamp to change. There are some transistors on the board, though I removed the muting transistors. The MASH player may not be as well constructed as say my Marantz CD50. You mean instead of a cap, you would use transistors? on the output
Thanks Derfnofred, so you are steering towards the 1642, and you find the 1602 and 4562 about the same in terms of sound? Caps on the dac supply pins
Hi Jcx, thanks. Yes the LM833 is IC802 and the IC891 which is a 4560, which I was thinking of replacing, but maybe its the LM that needs changing or both?
Oh, i see like a fan who follows an actor about. I am still confused which opamps to change
IC802 sees more hf hash from clock feedthru if the DAC does have internal sw C filter/op amp output
IC802 sees tons more hf if the DAC is a single bit direct output as implied to me by the DAC output waveform graphic
and as I said the R values around IC802 are too high for bjt input on current noise grounds
so a good jfet input op amp for 801 would be my priority since they in are general are more linear with hf imposed on the input than bjt input op amps
the ba4560 isn't very special, may have highish output I ability from its datasheet graphs - but not speced
if you don't need the possibly higher Iout then the opa1642 would improve on distortion performance there too
IC802 sees tons more hf if the DAC is a single bit direct output as implied to me by the DAC output waveform graphic
and as I said the R values around IC802 are too high for bjt input on current noise grounds
so a good jfet input op amp for 801 would be my priority since they in are general are more linear with hf imposed on the input than bjt input op amps
the ba4560 isn't very special, may have highish output I ability from its datasheet graphs - but not speced
if you don't need the possibly higher Iout then the opa1642 would improve on distortion performance there too
Your schematic shows the 0db test signal playing from the CD to be 6.2v p-p. With the power supply rails at 8.5v (near as I can tell), that only leaves about 7-8db of headroom, which is at best HALF of what is needed. I would suggest improving the power supply FOR THOSE ICs ONLY (I don't know what the rest of the circuit is doing) to a CLEAN, 10,000uF filtered +/-17 volts. Then your opamp replacements can be the best that they can be. As someone else suggested, those first ones should be FET types due to the high source impedance provided by the filtering. The OPA2134 is the best FET for the buck at around $3-4 each. The second one could be a bipolar type with good drive capability such as the LM4562--about the same price as the 2134.
Hi Jcx,
Thanks for explaining, so IC801, would be first to replace and also ba4560 with the same opamp opa1642, as the ba4560 is probably worse than a NE5532 etc.
Hi Dotneck, thanks for explaining. So for a low cost the LM4562 or OPA2134. There is only 2 large capacitors in the power supply 1 x 1000uf 16, and 1 x 2200uf 16v, and 4 x 100uf capacitors of various values and about 4 x 47uf 6.3 v caps,
Service manaul
Mega File Upload - hfe_technics_sl-pg440a_service.pdf
What I was meaning was installing EFs (emitter followers) as buffers between the MASH DAC and the subsequent analog opamp stages. This would allow the internals of the DAC to operate at their best. After that, attention would turn to improving the subsequent opamp stages. I'd raise the working impedances (change to JFET based opamps as jcx is recommending) and bias the outputs into classA with external CCSs.
A non solution to a non problem.
Electronic products are good or bad because of design, not because they useºexpensive parts.
If it were so, it would br EASY to design good stuff, just buy most expensive available, forget studying Engineering,reading all datasheets, having a well equipped Lab, eperimenting a lot, etc. , just replace a $1 part with a functionally same $15 one and presto, our amp sounds 15 times better !!!
Clearly it does not work that way.
Even IF the new Op Amp were 15 times better than the old one, ... the circuit is not made to take advantage of that, sound/performance will improve only IF the old part was used beyond maximum performance (say, a 741 asked to deliver clean 20kHz at a significant level) and were the only limiting factor.
Doubt a competent designer would do that.
Electronic products are good or bad because of design, not because they useºexpensive parts.
If it were so, it would br EASY to design good stuff, just buy most expensive available, forget studying Engineering,reading all datasheets, having a well equipped Lab, eperimenting a lot, etc. , just replace a $1 part with a functionally same $15 one and presto, our amp sounds 15 times better !!!
Clearly it does not work that way.
Even IF the new Op Amp were 15 times better than the old one, ... the circuit is not made to take advantage of that, sound/performance will improve only IF the old part was used beyond maximum performance (say, a 741 asked to deliver clean 20kHz at a significant level) and were the only limiting factor.
Doubt a competent designer would do that.
It makes sense, in parts ...
Clearly not everything is more expensive, is necessarily higher.
But the cheapest will never be the best. Why raw material not costs little, it is natural that good parts cost more expensive.
Unless particular company do not bother with the fact that the sale price is lower than the cost value. But I do not know any. 😛
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