Lovely. I have to admit most of this stuff is above my pay grade so I'm paying attention and soaking up the info. See what you guys come to as a conclusion.
I'll be readily available as a guinea pig to test certain things out. I have contacted one of my favorite taobao shops to do some measurements on my original and modified DX3 pro once I think the modified one sounds best. To make a comparison how that relates to measurements. Might be interesting to see what comes out. For now I'll be rolling opamps a bit
I'll be readily available as a guinea pig to test certain things out. I have contacted one of my favorite taobao shops to do some measurements on my original and modified DX3 pro once I think the modified one sounds best. To make a comparison how that relates to measurements. Might be interesting to see what comes out. For now I'll be rolling opamps a bit
Actually, we could describe what would happen if the opamp were operated open loop and preceded by a divide-by-a-million voltage divider, but understanding the relationship between that and the closed loop behavior requires too much math at this point for beginners. There would be slow settling time in time domain corresponding to what we think of as 100Hz in the frequency domain, for the open loop and voltage divider case, but it is not practical to use the opamp that way and we never do. What happens in the closed loop case is that feedback drives the opamp hard enough to turn on the transistors inside enough so that settling time is essentially the same at all frequencies. It is just a matter of driving it hard enough at each different frequency to turn it on enough that internal capacitances charge up essentially as fast a needed to prevent any settling delays corresponding with any audio frequency. Understanding how all that works is complicated, and so is trying to get useful open loop measurements since the open loop input signal would have to be so very small to keep the output from hitting the rails. However, it is easy to show there is no delay anywhere near 2.5ms at audio frequencies in the closed loop case. Maybe .25micro-seconds or something closer to that. Depends on the closed-loop propagation delay, is one way of thinking of it. Besides the feedback math, it is helpful to understand some things in terms of the time domain and some things in the frequency domain, so FFT type math is also needed to have comfort with the relationship between the two domains.
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wouldnt something like this be better suited for modding:
ES9038Q2M DAC I2S SPDIF Decoder Board CSR8675+aptx-hd Bluetooth 5.0 Module | eBay
ES9038Q2M DAC I2S SPDIF Decoder Board CSR8675+aptx-hd Bluetooth 5.0 Module | eBay
Don't know. I think at least one person has used that type. Depends a lot what the bottom of the board looks like since a good, continuous ground plane is one important consideration.
One reason people like the 1.07 boards is because the firmware makes it much easier to get get into the dac I2C registers rather than having to cut traces or lift MCU pins to get control of the bus. There is a way to get the MCU to halt I2C activity with the proper combination of pin jumpers.
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Hi! A little help here; I want to connect a Schiit Loki (tone control board) at the DX3’s internal HF amplifier (OPA2140). Some hints? Resistors? DC decoupling? Impedance adapters? Where to?
From Schiit Loki specs:
Output Impedance: 75 ohms
Input Impedance: 47K ohms
Topology: fully discrete, all-bipolar, symmetrical current-feedback design with no capacitors in the signal path and DC servo
Maximum Output: 10V RMS into 10K ohms
THD: Less than 0.002%, 20Hz-20KHz, at 2V RMS in/out, pots centered, active stage enabled, less than 0.01% at any potentiometer setting
Thanks!
From Schiit Loki specs:
Output Impedance: 75 ohms
Input Impedance: 47K ohms
Topology: fully discrete, all-bipolar, symmetrical current-feedback design with no capacitors in the signal path and DC servo
Maximum Output: 10V RMS into 10K ohms
THD: Less than 0.002%, 20Hz-20KHz, at 2V RMS in/out, pots centered, active stage enabled, less than 0.01% at any potentiometer setting
Thanks!
He posts regularly (used to at least) at audiosciencereview forum.
Thank you eljoantonyn. I'll go over there and take a look.
I suppose in one important sense they're hope-less. That is they all pretty much to a man believe there aren't any unsolved problems in audio, barring speakers. Just design to get perfect numbers, job done. No need for listening. What is the need for hope when all relevant problems have been solved?
Its like buying a car after checking the specs like 0 to 60 time, max speed, torque curves, drag coefficient etc without actually driving and seeing if its characteristics match your driving style.
@chinook9
I'm not sure about this particular model from Topping. Its marred with technical problems. Just visit the thread at audiosciencereview forum.
@chinook9
I'm not sure about this particular model from Topping. Its marred with technical problems. Just visit the thread at audiosciencereview forum.
I go over to ASR quite regularly to see what Amir's latest measurements show, he's getting better at doing them and I agree they're useful. He's also attracted various manufacturers to comment on the tests on their products which often makes interesting reading. But haven't posted there for a very long time.
It was nice to see a simple test weed out a bargain dac when I had looked there once. It had a buzz getting through the ps.
The testing is good for that anyways.
The whole name, look, and feel of that site are amusing to me however. It reminds me of the small emblems that ford used to put on the dashboards of their cars that stated “Radial Tuned Suspension”.
The topping products looked like they would be difficult to modify, very compact layouts.
The testing is good for that anyways.
The whole name, look, and feel of that site are amusing to me however. It reminds me of the small emblems that ford used to put on the dashboards of their cars that stated “Radial Tuned Suspension”.
The topping products looked like they would be difficult to modify, very compact layouts.
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