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Chord Huei Phono Preamp Review

wwenze

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#41
That interface...

At least I can tell the 2.2uF means extra yellow glow, but the rest of the colors may not be straightforward to most people.

Take for example that purple color of 320ohm. Purple light (or rather magenta) is red light + blue light. 1000ohm parallel 470ohm is 320ohm. So this is just a 4-LED colored led assembly where the corresponding color LED is turned on based on whether that resistor is connected or not.

If I were a poor student with insufficient money or technical knowledge I would use some ghetto solution like this. But this is not a product with low production budget or technical knowledge. Or at least I hope.
 

JohnYang1997

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#42
I would be conservative and rigorous to check if the A weighted noise floor is 0.18uV as speced. I don't think it's as low. Saying using a weighting to get rid of low frequency noise is not good enough. It also weights down the lower high frequency noise which is normally the much larger contribution in the integrated noise.
 

JohnYang1997

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#43
I think it was designed by a new engineer or by a high schooler using opa1612 and ran with it. Not at all considering the resistor noise and gain structure. Let alone actually measuring it. This is the type of performance DIYer would do for their first phono amp design.
 
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#47
Thoughts on the sophisticated wall adapter?
Looking at the above picture, the relays are in fact a major feature.....
 

solderdude

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#49
Thoughts on the sophisticated wall adapter?
Looking at the above picture, the relays are in fact a major feature.....
The wall wart is of no real concern I reckon.
The input voltage is filtered common mode (Schaffner) and then feeds the DCDC converter (on the left in the pic) that will create the internal voltage(s).
The incoming and filtered 12Vdc also drives the relays directly (I assume).
 

boXem | audio

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#50
inside:
View attachment 92190

Mostly power supply, and control or can there be parts on the bottom of the PCB as well ?
Well, I guess some opamp would be needed for amplification. Seems they are not aware that whatever 50 cents microcontroller has the oscillator embedded these days.
 

solderdude

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#51
Or the amp part is just a few transistors :eek:.. but it looks like most of the transistors are there to drive the relays so most likely there may be parts hidden underneath. Can't find pictures of this alas. Only the one from Chord itself. One would expect that if the bottom side also contains parts or a 2nd board is hidden underneath (unlikely given the size) containing the audio parts Chord would show this as well.
 

digicidal

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#52
Well, I guess some opamp would be needed for amplification. Seems they are not aware that whatever 50 cents microcontroller has the oscillator embedded these days.
Well, based on their DACs (which at least measure decently) they seem to be driven mostly by the "be different at all costs" motto. Even if it's much more obtuse in operation, we must make every aspect of the device (especially UI) completely different... because we can.

It's similar to the R2R adherents... if you can achieve a given level of performance with three components... achieving the same thing with 300 components has to be 1000% better right? :rolleyes:
 

wwenze

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#53
But hey, it has Rubycon capacitors! Not Samwha like the Hypex module.
 

digicidal

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#54
But hey, it has Rubycon capacitors! Not Samwha like the Hypex module.
Which is kind of ironic, since based on the measured performance, it would be a relief if this failed within a year or so. Less so regarding the cost however.
 

boXem | audio

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#56
Or the amp part is just a few transistors :eek:.. but it looks like most of the transistors are there to drive the relays so most likely there may be parts hidden underneath. Can't find pictures of this alas. Only the one from Chord itself. One would expect that if the bottom side also contains parts or a 2nd board is hidden underneath (unlikely given the size) containing the audio parts Chord would show this as well.
If the transistors we see are part of the audio path, then performance is impressive!
Opamps are boring, relays look cool, especially when LOTS of them. I can understand the choice of showing these knowing that 99% of people looking at these pictures have no idea of what they see.
Well, based on their DACs (which at least measure decently) they seem to be driven mostly by the "be different at all costs" motto. Even if it's much more obtuse in operation, we must make every aspect of the device (especially UI) completely different... because we can.

It's similar to the R2R adherents... if you can achieve a given level of performance with three components... achieving the same thing with 300 components has to be 1000% better right? :rolleyes:
In this particular case, I suspect more the reuse of 20 years old building blocks ;)
 

DuncanTodd

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#57
This sort of gear makes me wonder what I'm missing out not being a self appointed audiophile. My early 90s midrange(?) integrated stereo amp has a built in MC/MM phono pre-amp. I never felt it was lacking. If I get a well made high priced external phono pre-amp, am I'm in for some revelation?
Maybe I need to first invest $30K in upgrading the entire system to appreciate it.
 
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solderdude

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#59
If I get a well made high priced external phono pre-amp, am I'm in for some revelation?
Phono pre-amps are interacting devices. There is always an interaction between arm and cartridge. Not all of them are a good match. Then there is a substantial interaction between cartridge and pre-amp input and even the cable used is important.
Then there is the actual performance of pre-amp itself.
The latter is what Amir tests. Noise, noise spectrum, gain, distortion, dynamic range, headroom, frequency response, deviation from the RIAA standard.
These are all important by itself as there are many different cartridges that have varying 'needs' to perform optimally.

Here is the thing. When Amir measures Phono pre-amps it is driven by a 'standard' and anti-RIAA source that is not inductive.
This makes measurements comparable but may very well deviate from reality.
Not so much in distortion and noise but it can vary a LOT in FR because there is an interaction between cartridge (inductance, resistance) and capacitance (cable, arm-wiring) and for low frequencies even the arm combined with cantilever suspension.

This means that 2 phono pre-amps may measure equally flat under test conditions (neutral after RIAA) but may well be quite different from the same actual cartridge. There can be peaking or roll-off in the audible range which is not seen in tests.

For MM cartridges the input resistance is usually 47k but sometimes a higher resistance or combination with a capacitance can be more optimal for some cartridges. You could also very well have a 'tuned circuit' at a certain radio frequency (inductor, arm wiring as antenna, capacitance) will create a tuned circuit and semiconductors in the amp can become an 'AM-detector'.

To make the answer short: You could be in for a revelation when you happen to have a cartridge that is optimally loaded or loaded in a specific way that you may prefer but does not have to be correct.
Selecting the right cartridge, setting it up as perfect as possible, loading it correctly and have low noise, low distortion, plenty of headroom and outputting enough voltage for today's 'standard' 2V inputs may well give more revelation than simply changing the pre-amp or its settings.

So aside from the tonal balance (FR) of the cartridge given at a specified load the actual FR may be different on different preamps, arms, cabling and this is very measurable (using a record as source).

In the old days most MM inputs (and MC inputs) all were quite similar and it was universally understood that cartridges (needle, cantilever, magnet, coil) determined the sound. And it does.
Higher end pre-amps can be configured to have better 'synergy' with various cartridges but as there is a difference between cartridges that isn't there under 'lab test conditions' the FR (tonal balance) may differ from what is measured.

In the end we all know vinyl is not more accurate and vastly inferior when it concerns capturing and reproducing audio signals (music) but the 'shortcomings' of this system and 'tuning' as well as perceived SQ of vinyl may well attract a lot of people. They care less about 'accuracy' but more about 'presentation' and their personal preferences concerning sound.
 

Blumlein 88

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#60
It is an overpriced underperforming device. That's it. Better is available for less. You know all you need to know about this.
 
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