T/F? All analog inputs > ADC?

[Joseph Jones]

or Le120: True or false?  All analog inputs pass through ADC, are digitized.

Independent confirmation is helpful in this case.  I'd prefer my strain gauge phono stay in the analog domain rather than pass through ADC.  Has any pro or amateur review described audible distortion in the ADC?

If true, I suppose I can adapt my thinking to it.      

Comment at THIS review: "...is actually class A and class D run in parallel all the time and at all levels. Class A defines the sound character and provides voltage while the class D stage deliver current and ‘drive’. As far as I’ve understood, the class A amp also outputs a correction signal (created by the powerful DSP) to cancel the switching noise inherent to most class D..."

Peter Walker of Quad invents "Current Dumping" amp:
"...Peter put this principle into practice using two amplifiers per channel instead of one. The first stage ‘error’ amplifier is low powered but very high quality. The second amplifier is high powered, but of lesser audio high quality. (It’s a lot more difficult to achieve very low distortion in high powered amplifier stages). Peter designed a way to compare the high powered output with the original audio input and derive the required error correction signal which is then injected into the audio path, in such a way that the high power audio output achieves a very low distortion figure, even at very high power levels. This innovative product earned Quad the Queen’s Award for Technological Achievement in 1978..."

In the early-mid 00s Linn released their "Chakra" amps, which employ Quad's current dumping circuit modified/shrunk to analog ICs.  I very much enjoyed the performance of my Majik Chakra power amp.

I suspect Devialet further improved Walker's invention, fully converting the current dumping stage to a digital platform (ideal for this purpose), while maintaining a Class A analog stage to correct errors in the current dumping section.  The fact that the error correction circuit acts in the digital domain likely increases its accuracy, contributing much to the apparently stellar performance.

[Pim]

Joseph,

True, all inputs are digitized and go through a DSP in most cases.

Don't read too much into the comparison with the Quad amplifiers. If you were comparing cars, the comparison would be something like, they both have 4 wheels, an engine that runs on petrol and some wind screen wipers.

I don't have a record player but have a browse around this site and you will find the digitized phono input of the Devialet is really good.

The best advice I can give you is stop reading and go to a shop and have a listen (Bring your wallet too. You won't want to go home without one)

Cheers,

Pim

[Joseph Jones]

Pim,
Thanks very much!

...True, all inputs are digitized and go through a DSP in most cases...

Unfortunately, "all" and "in most cases" are mutually exclusive.  All is 100%, and "most" = some ratio <100%.  If you could edit or clarify, I'd be very thankful.   

Don't read too much into the comparison with the Quad amplifiers. If you were comparing cars, the comparison would be something like, they both have 4 wheels, an engine that runs on petrol and some wind screen wipers.

Quad's current dumping architecture is unique.  Prior to Devialet, only two known OEM employed it, Quad and Linn.  Till someone specifically says otherwise, based on my earlier quotes, I suspect Devialet's circuit is similar, with the major difference being a digital current dumping stage replaces the analog stage of Quad and Linn (Linn employed IC's but they are analog, not digital).

If above is correct, it seems appropriate to give credit where it's due, and in this case, that would be Peter Walker of Quad, another feather among many in Peter's cap.

[Pim]

Pim,
Thanks very much!

...True, all inputs are digitized and go through a DSP in most cases...

Unfortunately, "all" and "in most cases" are mutually exclusive.  All is 100%, and "most" = some ratio <100%.  If you could edit or clarify, I'd be very thankful.   

Don't read too much into the comparison with the Quad amplifiers. If you were comparing cars, the comparison would be something like, they both have 4 wheels, an engine that runs on petrol and some wind screen wipers.

Quad's current dumping architecture is unique.  Prior to Devialet, only two known OEM employed it, Quad and Linn.  Till someone specifically says otherwise, based on my earlier quotes, I suspect Devialet's circuit is similar, with the major difference being a digital current dumping stage replaces the analog stage of Quad and Linn (Linn employed IC's but they are analog, not digital).

If above is correct, it seems appropriate to give credit where it's due, and in this case, that would be Peter Walker of Quad, another feather among many in Peter's cap.

All inputs are digitized. 100%.

In some cases, like SAM or if you're using tone controls, DSP will be used. Before your post I had never heard of the DSP correcting for the class D amp's shortcomings but that doesn't mean it's not done. Someone just forgot to tell me

I also don't know anything at all about the difference in Quad's and Devialet's architecture but I do know Devialet's work a treat. 

[ogs]

Oh dear. The Quad 405 sounded horrid. Linns amps may have sounded better. The ADH in the Devialet amps sounds fabulous. I do not think it is necessary to give any credit to Peter Walker in this regard. And yes, the DSP is part of ADH and used for correction purposes.