You just demonstrated a total lack of understanding about industrial production and the market. There is about a factor of 6 to 8 (or much more) between material costs and consumer pricing.
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Topping Pre90 Review (preamplifier)
- Thread starter amirm
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May be old components, but if they are good what's the problem? I would actually say that anyone that claims "OPA1612's [] are Meh" has a problem. These are among the finest integrated components around.
Maybe you never heard of negative feedback, and what it can do. Or maybe you believe that it is always bad?
I find it hard to believe that an op-amp, or rather its reputation, can permanently ruin your listening experience…
If you think about your entire system, the listening room, the curtains or cushions or the floor of the listening room, your ears, your perception and your taste, the electrical system in your home, the recording, how it was obtained, with what instruments, how it was mixed, how it is reproduced, the temperature of the recording and listening environment, the right position of the speakers in the room, the rack or furniture between the speakers, etc. etc.,
If you think about your entire system, the listening room, the curtains or cushions or the floor of the listening room, your ears, your perception and your taste, the electrical system in your home, the recording, how it was obtained, with what instruments, how it was mixed, how it is reproduced, the temperature of the recording and listening environment, the right position of the speakers in the room, the rack or furniture between the speakers, etc. etc.,
It is designed as the equivalent of a composite amplifier with nested feedback loops done entirely in a discrete way. You should read read mocenigo's post again, really..
Do you even have some electronic design credentials? Or just an enthusiastic DIY'er?
Actually, I have to correct myself. There are at least 3 different version of the Topping NFCA circuit and I am not 100% sure which product uses the discrete version. But not the Pre90.
This one should be a composite amplifier with the TPA6120 inside the feedback loop of the OPA1612, with the TPA6120 providing the power and the OPA1612 the precision. This is something well understood, and the results speak for themselves. However, the passive components are there to deal with little quirks of the used ICs and depend a lot on stuff like phase rotations to guarantee stability. Replacing the ICs is most likely a recipe for instability and thus disaster.
Even Stereophile put the Pre90 in their Class "A" preamps, in other words in the same league with products costing 35K-50K USD and more.
I have been in electronics for 40+ years so thats my job (not audio though) - I know electronics production very well and the ratio here of part cost to product cost is obscene. Essentially this is a $35 Aliexpress board with a nice case, a display and some relays/ resistors instead of a Pot.
And while we are on the subject why have two obviously different batches of OPA1612 been used on the boards (2 x OPA1612 batch 1) next to the tpa, and (2 x OPA1612 batch 2) at the input ? The second batch has very faint printing on it not like a standard TI part at all (unlike part 1).
Why would the assembly subcontractors load 2 different batches of the exact same part into the placement machine, and place them in set positions ?
Could that indicate that there is some "issue" with batch 2 ?
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Do you think TI doesn't know the market value of its products?
When OPA627's cost $30 for one single opamp meaning to replace a dual opamp the cost is $60 - so $240 to replace the 4 x OPA1612's on the Pre90.
Yet they wholesale the OPA1612 out at $3.00 and the tpa6120a2 out at $2 - and believe me if buying on a call-off from a tier 1 distributor those costs will be even lower - do you really believe that those parts are so great and so in demand that they would let them go at those bargain bin prices?
Well, casework also has a cost, all the other components, connectors, etc. they have to maintain inventory.
They have to pay the person that designs it, and all the other employees.
But apparently you have been working in electronics for 40+ years for free?
If some of the opamps had issues then this would show in measurements? But, again, this is one of the most transparent preamplifiers ever designed.
You are really scraping the bottom of the barrel…
Exactly. Market value.
The 1612 is optimised for low noise.
Both noise and distortion of the 6x7 family is something like 6Db higher than the 1612, but it has been designed for applications like optoelectronics, precision instrumentation, data acquisition, sonar, etc. This explains the price, because it is designed to go into very expensive stuff. They also have some rugged industrial version, and I guess they are the really expensive ones.
Yes, the 627 can do audio and they mention it. It is definitely good for audio as well.
Price is not a quality measurement.
misterdog
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You prefer to listen to the noise of a Pot., rather than the 0.5dB precision of the Japanese relays ?
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Doing what?
Well despite all the talk of Opamp rolling being impossible due to nested opamps within more nested opamps within yet more opamps blah blah blah......
I can provisionally report that the OPA2828 (dual 828) does appear to drop straight in, because the opamps are no more than the Filter/ I/V Gain stage.
And WoW what a difference it makes!!
The clarity now of the top end is much improved and one of the biggest differences is also in the 450-1100hz range now so clean, punchy and detailed.
But much much more testing is required.
Remember I mentioned that there is not one but TWO Opamp footprints on the circuit board?
I have never seen this done before because by the time a board goes into production these things are usually nailed down, and there are plenty reasons not to do it.
The second smaller TSOP having a thermal pad underneath which incidentally happens to be a requirement of a OPA2828.
I now wonder if they made 2 versions? One for the early test/ review samples using the OPA8282 (or similar), and then the low ball OPA1612 for us, you know the paying plebs. Its not unheard off sending the "White Glove" version to the reviewers.
Might that account for the disparity in reviews/ versus real world experiences?
4 x OPA2828's is after all $50 and in volume that's a big difference!
I can provisionally report that the OPA2828 (dual 828) does appear to drop straight in, because the opamps are no more than the Filter/ I/V Gain stage.
And WoW what a difference it makes!!
The clarity now of the top end is much improved and one of the biggest differences is also in the 450-1100hz range now so clean, punchy and detailed.
But much much more testing is required.
Remember I mentioned that there is not one but TWO Opamp footprints on the circuit board?
I have never seen this done before because by the time a board goes into production these things are usually nailed down, and there are plenty reasons not to do it.
The second smaller TSOP having a thermal pad underneath which incidentally happens to be a requirement of a OPA2828.
I now wonder if they made 2 versions? One for the early test/ review samples using the OPA8282 (or similar), and then the low ball OPA1612 for us, you know the paying plebs. Its not unheard off sending the "White Glove" version to the reviewers.
Might that account for the disparity in reviews/ versus real world experiences?
4 x OPA2828's is after all $50 and in volume that's a big difference!
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Any actual evidence of this insanity?
Keith
Keith
Uh huh.
Yes, some testing with basic controls.
Let me know when you've done that and I'll let you post in this thread again. Until then, this has gotten silly.
It is quite likely that the first opa1612, that is a buffer stage before the actual NFCA, can be replaced without harm, at most colouring a bit if its own feedback loop is left unchanged, but without introducing instability. I would not touch the 1612/6120a2 complex.
Proper controlled double blind test? (Which means you need two pre90s, one unmodified and one modified.
Otherwise, this has no value (not even as a subjective evaluation)).
Cheers
NicS
Member
This is what draws me to ASR.
Evidence based analysis, backed up by empirical observations is my preference. I'm sick of being told that a piece of equipment "sounds better" because is costs $20K and is described in flowery abstract terms that cannot be quantified. I'd prefer to know that the measurements taken demonstrate good design and performance. It does not matter to me if technology is old, as long as it is fit for purpose and does the job. I don't care if the op-amps are not the highest specification, if the overall result is a good one.
I have to say, it makes me chuckle to see the covers get pulled off some of the silly claims made by the audiophile community. Watching audio engineers roll their eyes when talking about some of the claims made by audiophiles about expensive power cables is priceless. And that, as we know, is just the tip of this particular iceberg...
Evidence based analysis, backed up by empirical observations is my preference. I'm sick of being told that a piece of equipment "sounds better" because is costs $20K and is described in flowery abstract terms that cannot be quantified. I'd prefer to know that the measurements taken demonstrate good design and performance. It does not matter to me if technology is old, as long as it is fit for purpose and does the job. I don't care if the op-amps are not the highest specification, if the overall result is a good one.
I have to say, it makes me chuckle to see the covers get pulled off some of the silly claims made by the audiophile community. Watching audio engineers roll their eyes when talking about some of the claims made by audiophiles about expensive power cables is priceless. And that, as we know, is just the tip of this particular iceberg...
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NicS
Member
Can you send your upgraded Pre90 to Amir so he can evaluate it? I'd be curious to have your claims of "WoW' substantiated by measurement. Not questioning your claims, I'd just like the confirmation bias removed from there evaluation through measurements. I hope you too see the value in this.
Also curious to substantiate the assertion of a "white glove" reviewers version of the Pre90. I find that a bit of a reach, considering the difference in price of the changed components you mentioned is hardly great for such a reported improvement in performance. But again, measurements will reveal any sleight of hand on the part of Topping.
drewdawg999
Active Member
Just topped off my Pre90 with the Ext90:
Pretty happy with the results. Pictured is the 2nd RCA input for cassette player, really gotta crank it for that thing, never had to turn the Pre90 that loud before. But cassette player sounds great, kind of a pleasant surprise. So it opens up more analogue magic with my considerable cassette library, for I was a proud member of the Columbia cassette club. Now on my wishlist is a phono preamp with a balanced XLR out (and the Classic Audio MM Pro seems to fit that bill). Also have an old high-end Chinese CD player with XLR out that was renowned for its bass output, gonna have to give that a try. Gonna have to put all its fancy circuitry to good use, as the digital out sounds the same as my Sony ES changer.
Pretty happy with the results. Pictured is the 2nd RCA input for cassette player, really gotta crank it for that thing, never had to turn the Pre90 that loud before. But cassette player sounds great, kind of a pleasant surprise. So it opens up more analogue magic with my considerable cassette library, for I was a proud member of the Columbia cassette club. Now on my wishlist is a phono preamp with a balanced XLR out (and the Classic Audio MM Pro seems to fit that bill). Also have an old high-end Chinese CD player with XLR out that was renowned for its bass output, gonna have to give that a try. Gonna have to put all its fancy circuitry to good use, as the digital out sounds the same as my Sony ES changer.
NicS
Member
Are you using the XLR and RCA outputs concurrently? If not, press the Volume know (but do not hold - this will mute the volume) then select the output plug type you want. I just use the XLR only output. I can see you have your set to R+X. Both RCA and R+X (RCA + XLR) will result in a 6dB increase in gain. This tricked me at first. Couldn't figure out there the extra 6dB was coming from. Consequently I had my output set to -6dB to reach zero gain.
The things you learn....
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