DAC, DAC ..goose!

[w00ds153]

Hey guys, my Topping D30 DAC just arrived (kewl), but the JDS Atom amp I got to go with it is still a few days out and so are my headphones, so I hooked the DAC up just to check it out and it got me thinking ..what exactly are the DACs doing in this config - I have my CD player going into the D30 via an optical cable, then using the analog outs of the D30 to go into an integrated stereo amp. So if I'm going into the D30 from the CD player via optical then the D30 is active (it's str8 DACing ..it's 'converting), right? Got it. But once it goes into my integrated stereo amp via converted analog signal, what's my integrated stereo amp do with it? I know it has a DAC, but the signal coming in from the D30 is already analog, so ..? Now the integrated stereo amp has a button on the front called 'Pure Direct' and from what I understand you push the button and it gives you an unaltered straight feed-through of whatever input you're using, so whatever DAC is before it is what you're hearing. Cool. Here's my question - when I turn 'Pure Direct' off does the DAC in the stereo amp become active like it would if it was being fed a digital signal and do anything to the analog signal coming into it from the D30? You know, like if it's already coming into the stereo amp via analog signal, what can the stereo amps DAC do? I'm just curious. I hear no difference when switching 'Pure Direct' on and off. The only difference to me, when it's turned off (putting the amp back in control, I guess), is that I can use all the dials on the top plate of it (bass/treble/balance/loudness) and when Pure Direct is turned on I can't. I guess you'd have to know the specifics of my amp to answer this question maybe, but let's say, generally speaking, what does a DAC do when it receives an analog signal from another DAC ..does it do anything? I guess I could have just asked that one freakin question LOL. Lastly and most importantly, the real question everyone thinks about but never asks ..if you ran (5) DACs in a chain with each other (for ultimate sound clarity, of course) ..would you be able to hear the future? Thanks.

 

[M00ndancer]

It's my understanding that if you use an external DAC to RCA in (analogue in) the the signal goes to the amplifier directly (via tone controls, unless put in "Direct mode") without engaging the internal DAC at all. (I'm a bit sceptic about the "Direct mode" as well, not so sure that it only disables any sound controls nothing else.) The DAC = Digital to Analogue Converter. So to be able to run 5 of them in serial you have two options:
going from a digital signal to an analogue signal -> use an ADC(Analogue to Digital Converter), convert back to analogue signal. repeating un til you passed the signal 5 times. Probably will give you a degraded signal.
Second option is to pass the digital signal -> digital signal and then convert it in the last DAC to an analogue signal. Unless you get a bit perfect transfer you might have artifacts there as well.

Not an expert on what will happen if you daisy chain DACs, but it's nothing I would recommend.

 

[amirm]

Your integrated Amp does not have a DAC. It needs an external DAC either in your CD player or from Topping to play anything digital. The amp only knows how to take a weak analog signal and make it a loud one to drive speakers.

The Pure-direct button most likely bypasses the tone controls, creating a shorter path for audio. If we measured it, it might show lower noise floor but that may not be an audible difference.

 

[w00ds153]

Aww man, I think I'm confused. I'm almost embarrassed to ask this because I feel like there might be something I'm totally missing ..but doesn't my integrated amp have to have a DAC to be able to accept and produce sound from the digital inputs, both optical and coax? I understand the outputs of the D30 are analog so they feed into the integrated amp and nothing needs to happen or does happen that way, but what about when my CD player his hooked up directly to the amp via optical or coax digitally ..doesn't the amp need to convert it to analog to output sound to speakers? Does that make sense? I'm mixed up on something. Thank you!

 

[amirm]

Oh, if it has digital inputs, yes. I tried to find the model and the one I found didn't have any DACs.

And yes, if you connected optical from CD player to the amp, you are using its DAC.

 

[w00ds153]

10-4! So even though the integrated amp has a DAC, when I'm feeding it an analog signal (say from the D30 or even a CD player), it's already converted, it's analog, and there's nothing the integrated amp can or will do (conversion-wise) because there is nothing to do anymore, right? So like you're saying, anything going into my integrated amp via analog is being output through it untouched from whatever DAC is feeding it those analog sigs ..because it's already analog. I think I'm gonna be able to sleep tonight! Feedback greatly appreciated, Amirm.

 

[M00ndancer]

Ok I did dome digging: If it's an A-S301, then you have one optical and one coax digital input. So it has a DAC, no idea how good it is.

 

[amirm]

10-4! So even though the integrated amp has a DAC, when I'm feeding it an analog signal (say from the D30 or even a CD player), it's already converted, it's analog, and there's nothing the integrated amp can or will do (conversion-wise) because there is nothing to do anymore, right? So like you're saying, anything going into my integrated amp via analog is being output through it untouched from whatever DAC is feeding it those analog sigs ..because it's already analog. I think I'm gonna be able to sleep tonight! Feedback greatly appreciated, Amirm.

Correct. Not to confuse you too much but there are some devices that convert analog back to digital, then back to analog! They do this if they have features that only work on digital streams (e.g. room equalization). In your case though it works as you say.

 

[jsrtheta]

Your integrated Amp does not have a DAC. It needs an external DAC either in your CD player or from Topping to play anything digital. The amp only knows how to take a weak analog signal and make it a loud one to drive speakers.

The Pure-direct button most likely bypasses the tone controls, creating a shorter path for audio. If we measured it, it might show lower noise floor but that may not be an audible difference.

I can't decipher the model number on this Yamaha. But Yamaha "Pure Direct", if memory serves, bypasses tone controls, the balance control and the loudness control. To be fair, Yamaha changed stuff up a lot. One other thing wrt Yamahas: If it has a "CD Direct" along with a "Pure Direct", do not use the "CD Direct". The signal gets routed through an unneeded buffer.

 

[Djsedaw]

From the look of the box its sitting on its a Yamaha A-501!

 

[M00ndancer]

From the look of the box its sitting on its a Yamaha A-501!

So true! Blindness first affects the eyes. Either way it's same line of amps. only differ in power output.

 

[sonci]

Just use cd player analog out, those are much beter than the Topping..

 

[JJB70]

Just use cd player analog out, those are much beter than the Topping..

I have to admit, if people are using a traditional CD player then they already tend to have perfectly adequate DACs and I can't really see the point of adding an external DAC between CD player and amplifier. An external DAC makes sense if you want to be able to feed digital sources which don't have a DAC to an analogue amplifier. I am somewhat bemused that DACs receive so much attention and are now so prevalent as of all the parts of a hifi chain I wouldn't identify the DAC as the component most liable to degrade performance or offer good gains if upgraded.

 

[w00ds153]

I have to admit, if people are using a traditional CD player then they already tend to have perfectly adequate DACs and I can't really see the point of adding an external DAC between CD player and amplifier. An external DAC makes sense if you want to be able to feed digital sources which don't have a DAC to an analogue amplifier. I am somewhat bemused that DACs receive so much attention and are now so prevalent as of all the parts of a hifi chain I wouldn't identify the DAC as the component most liable to degrade performance or offer good gains if upgraded.

I understand completely. I bought an external dac, headphone amp, and headphones but am yet to receive the amp or the headphones, so thought I'd do some experimenting with the external dac by hooking it up different ways etc. (you know, I can't just stare at a new toy in the box) ..but learning from everyone's responses on here has been the best part! Thanks for all the feedback!

 

[w00ds153]

I should probably just google this or start a new thread? ..sorry. Is there a device you can put in-between an analog or digital signal that will display the Bit and kHz of the audio coming through? I notice higher-end units will show this on their display or have 24/96/192KHz on the top plate with a small light next to each one that can light up.

 

[w00ds153]

Also, without opening a can of worms ..would it be safe to say (for the average listener) to just use whatever is the most modern DAC in your system? Is the DAC in a $5,000 CD player from 1999 even relevant to modern entry level DACs due to advances in the tech?

 

[jsrtheta]

From the look of the box its sitting on its a Yamaha A-501!

Yeah, I guess that could be a clue. Which I don't seem to have these days...

 

[jasonq997]

Just use cd player analog out, those are much beter than the Topping..

Probably not correct from a purely technical point of view, but I doubt anyone can hear a difference.

 

[jsrtheta]

Anyway, according to the manual, "Pure Direct" functions as I said: "Pure Direct" takes the bass, treble, balance and loudness controls out of the circuit.

Yamaha sure makes good integrateds.

 

[M00ndancer]

Just use cd player analog out, those are much beter than the Topping..

In what way? Do you have measurements to back it up? I'm sure that the CD player is "good enough" but better than the D10? D30?