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Topping A90 Discrete, what is this new version not available in the topping website ?
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wacomme
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I'm a noob. What's advantages, or disadvantages, of digital volume control over analog other than the ability to use a remote? I ask because I'm considering buying an A90 (or A90 Discrete) + D10b. I'm planning to connect my MacBook Air (M1) to HP and powered speakers. I would like to be able to control the volume of either HP or speakers via the amp volume dial (+ remote for the A90 Discrete). I would also like the volume setting for both HP and speakers to be remembered and set to the last respective setting when I toggle switch between HP and speakers. Is this possible with both the A90 and the A90 Discrete? Is it also possible to control either (or both) HP and speaker volume via the computer keyboard with computer - dac - amp - HP or speakers (via amp inputs, be they balanced or unbalanced)?
cheapmessiah
Active Member
You can have an analog volume control with a remote too, you would only need to motorize the potentiometer. The real advantage is channel matching, and pin point accuracy when targeting a volume level, specially if you do it repeatedly.
I'm definitely going to wait for measurements and some reviews by other people on Amazon, Reddit etc..
Topping always had problems with channel matching and quality control in General.
Sure enough they sell lots of devices compared to some other brands but Ive seen so many reports about the A90 &D90SE with channel miss match or the USB input dropping signal and causing noise after a couple of months that I always actually avoid purchasing something from them.
But if the A90D is really going for the same price as the A90 it might be worth the risk..
cheapmessiah
Active Member
Im interested on a high power amp, the A90D might be it, I just bought a monolith 887 on sale that I can unload on the used market losing very little money so I can wait for the A90D to be tested and any flaws that early adopters might find to be fixed.
I too am worried about this "quick to market" companies using the early adopters as beta testers of their products.
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I have the a90 and I'm happy, I have also a Nuprime AMG https://nuprimeaudio.com/product/amg-hpa/?v=cd32106bcb6d which has digital volume control, both ahve a good channel match...but the AMG HPA is very confortable to use with te rempte control...
DVDdoug
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That can be a "complicated question"...
The main issue with regular potentiometers is that left & right don't track exactly. Well... Nothing is "exact" in analog but often it's good enough (better than human hearing). Left and right will always match at zero and maximum but they can be mis-matched in-between.
...I have an old mixer that I built, and there some "play" between the two ganged pots. One pot moves before the other and you have to move it back-and-forth to get left & right balanced! ... I don't remember and I don't use it anymore so I might have actually fixed the play but I remember that left & right still don't track.. (You shouldn't get that bad of a problem in a well-made commercial product but it still can sometimes be imperfect.)
"Digital" volume control can be done two different ways - Sometimes it's just digital control of an analog circuit, and usually that's preferred.
Usually it's done in the digital domain and some people try to avoid that because when you reduce the level digitally you aren't using all of the "bits" and you're loosing resolution. But that's not as bad as it seems and you won't hear any loss of quality/resolution unless you re-amplify after a LOT of attenuation. It's usually OK for "everyday" volume control because you still get full-resolution when you turn it up to full volume where the resolution is most important.
Plus... You also loose resolution with analog attenuation because by reducing the signal you are reducing the signal-to-noise ratio.(for any noise that's introduced after the volume control). And again, the loss of resolution isn't a problem unless you re-amplify, boosting the noise and signal together, making the noise more noticeable.
wacomme
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Thanks. Apparently with analog, if you have HP and speakers attached to the amp via balanced inputs (e.g., A90) and you switch back and forth between HP and speakers, the volume setting is not remembered, respectively. However, with digital (e.g. A90 Discrete), the previous volume setting is remembered, respectively, between HP and speakers. Is this correct?
Vini darko
Major Contributor
Looks good. Why not just use the volume circuit from the pre90 that would circumvent the need for gain controls. The remote sensor doesn't look very usable behind that facia. I wonder if topping is going with discrete output stage in this amp.
wacomme
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I don't understand what you're saying. Pre90?
But with a digital volume control there will always be the risk that some setting resets and your loudspeakers or headphones get full volume when U left it previously at a normal volume.
I've read a couple of reviews today about the other topping devices where that happened.
U don't have that problem with a analoge volume control.
Nothing is perfect.
A R2R volume control like fluxlabs uses would be nice
Vini darko
Major Contributor
The topping pre90. Its a pre amp
I'd also like to mention that a stepped-attenuator based design will inherently have lower distortion than a potentiometer of equivalent impedance, because there is only a single passive element in the former (as opposed to nonlinearities in the latter's wiper contact, among other nuances). It doesn't really make an audible difference in any competently designed product, but a stepped attenuator using an input buffer with low-impedance resistors will always achieve greater SNR and SINAD than a volume pot. The pros are:
+channel matching
+consistency of volume ratio
+potentially lower noise floor
Apart from complexity/cost, the only real disadvantage is the loss of continuous volume control, but even this is not a problem when the resistors are chosen to attenuate in 0.5 dB increments. Some really high-end equipment can even do it based on 0.1 dB steps (or lower!). Of course, having the volume control in the digital domain is still going to be the best way to do it, and with current DACs delivering 21+ bits of SNR, there is really nothing to gain from having analog attenuation instead.
TOPPING A90 vs TOPPING A90 Discrete Comparison Chart
The upgrading of a classic is an exciting but potentially confusing event. Everyone loves quality of life improvements, but no one likes having to hack through a jungle of specs. We’ve created this comparison chart to help you quickly and easily judge the differences between the classic A90 and...
cheapmessiah
Active Member
I thought the A90D was coming at the same price as the original A90 and it would supersede it.
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