Dac for an arcam delta 170.3 transport

Dedicated to the silver disk spinner
Ant
Needs to get out more
Posts: 1650
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#16 Re: Dac for an arcam delta 170.3 transport

Post by Ant »

Hi greg, missed this last night
I bought a topping e30 dac for a shade under 100 quid before i saw your post..
Saw some reviews of it which were relatively good and a few people mentioned topping dacs. I figure if i dont like it it will sell on easily enough.
Sorted
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
Ant
Needs to get out more
Posts: 1650
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#17 Re: Dac for an arcam delta 170.3 transport

Post by Ant »

The topping e30 dac arrived today, ive hooked it up to the squeezebox to test it as the delta is yet to arrive.
Initially abit bass light with the rubbish cables ive used, but after a couple of hours its started to fill out
The squeezebox on its own outputs gives me a dull headache after a while, it seems to have a high frequency hash over the music. All 3 sb classics ive had have done this, no such nasties with the topping dac on the end of it.
I have to say, the thing sounds remarkably grown up for a 100 quid budget bit of kit.

But, the caveat is, that i havent had a 'serious' digital bit of the system in at least 10 years. The last nice bit of digital i had was an inca design katana cd player that i bought myself as a treat out of my redundancy money 11 years ago, and then when i got made redundant again, it got sold. Since then, ive only had old philips cd players and the sb's.
So, it could be crap, but i just cant tell..........
Like it though
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
Ant
Needs to get out more
Posts: 1650
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#18 Re: Dac for an arcam delta 170.3 transport

Post by Ant »

The delta has arrived, waited for a couple hours for it to warm up to room temperature before i powered it up just to be on the safe side as it was pretty cold.

Sounds quite alot better than the squeezebox does when playing the same songs, which were ripped from the same cds that the delta is playing.

Now to me, data is data, and i would have thought that it should be pretty much the same, as the sb is feeding the dac the same data as the delta is.
Unless not all digital output boards are made equal.
or something is being lost or added by the wifi data transfer to the sb.
Or perhaps transports do make a difference

Welcome back old friend
Need some audioquest jade interconnects to go with it :D
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
JamesD
Old Hand
Posts: 894
Joined: Tue Oct 09, 2007 4:26 pm
Location: North Yorkshire

#19 Re: Dac for an arcam delta 170.3 transport

Post by JamesD »

Yes to all the above...

The thing about digital signals is that they aren't.... the audio analogue signal is digitally encoded but the digitally encoded signal is transmitted through the analogue domain - so it is subject to all the usual analogue distortions - that the audio is digitally encoded greatly reduces the effect of the analogue signal transmission but it does leave an imprint on the digital signal that may (in practise does) have a subtle effect on the conversion of the digital signal back into the audio analogue domain...

Digital signal processing people will claim that the digital signal can be reconstituted from the analogue transmitted digitally encoded signal back into an accurate facsimile of the original - and they are right it can but even then the vagaries of the DAC will change the audio analogue signal between different DAC and the reconstituted signal is not the original signal from the ADC - now-a-days it can be a much 'better' digitally encoded audio signal than the original for various values of better...

Now-a-days digital audio has very good sound quality and reasonable prices and amazing 'convenience' factor but perfect sound or even identical sound through different systems isn't possible in the real world...

And thats before the different way people hear the same sound :-)
User avatar
Nick
Site Admin
Posts: 13656
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#20 Re: Dac for an arcam delta 170.3 transport

Post by Nick »

Yes to all that, but if the same (digital world) data stream is leaving the squeezebox and the CD player (we don't know). which it should, and they are both going into the same dac (which I think in ant's case they are), then the scope for all those changes are limited a lot to the extraction of the i2s and clock (or whatever is used internally) in the dac. Which to me points to a difference either in the sb or cd player transmitter AND the dac's receiver. Assuming all other things remain equal and there isn't any ground shenanigans going on.
Little known fact, coherent thought can destructively interfere with itself leaving no thought at all, that’s why I prefer incoherent thought.
JamesD
Old Hand
Posts: 894
Joined: Tue Oct 09, 2007 4:26 pm
Location: North Yorkshire

#21 Re: Dac for an arcam delta 170.3 transport

Post by JamesD »

Sure thing and I would look carefully at the wifi signal and associated spectrum - I wouldn't be surprised if there is another router in the vicinity on the same or adjacent channel...
User avatar
Nick
Site Admin
Posts: 13656
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#22 Re: Dac for an arcam delta 170.3 transport

Post by Nick »

Sure thing and I would look carefully at the wifi signal and associated spectrum - I wouldn't be surprised if there is another router in the vicinity on the same or adjacent channel...
What are you thinking that would do?
Little known fact, coherent thought can destructively interfere with itself leaving no thought at all, that’s why I prefer incoherent thought.
Ant
Needs to get out more
Posts: 1650
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#23 Re: Dac for an arcam delta 170.3 transport

Post by Ant »

The dac as far as i can tell should be seeing the essentially the same data stream up its optical input, the cd transport sending the original data from the cd and the sb sending a copy of that data. I just swapped the optical cable from the sb to the transport so there shouldnt be any appreciable difference in terms of the data stream or the reciever in the dac as its the same reciever.
Obviously there is nothing between the transport and dac other than the cable, wheras the data is travelling from the mac via wifi to the sb, and is then sent via the optical sender on the sb.
So an extra link. perhaps some error correction in the sb to reconstitute the datastream from the wifi aerial and reject any noise on it, and some error correction when the cd was initially ripped via itunes to the mac hd. There is also the lms server software, which may be doing some jiggery pokery when it buffers the data to send the packets.
But still, surely the data the dac interprets should be nigh on identical to whats read off the disc in the first instance, or as near as possible...
Me brain hurts.....
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
User avatar
Nick
Site Admin
Posts: 13656
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#24 Re: Dac for an arcam delta 170.3 transport

Post by Nick »

The dac as far as i can tell should be seeing the essentially the same data stream up its optical input, the cd transport sending the original data from the cd and the sb sending a copy of that data. I just swapped the optical cable from the sb to the transport so there shouldnt be any appreciable difference in terms of the data stream or the reciever in the dac as its the same reciever.
Words like "essentially" are the problem here. As James pointed out, that's an analogue connection and both ends are deciding what a 1 and a 0 looks like and are deciding when one turns into the other. At least being optical, it takes the ground out of the setup.
Obviously there is nothing between the transport and dac other than the cable
Well, there is the real time extraction of data from the CD, the encoder to the data stream and the optical transmitter. Far from nothing. We don;t know if the DAC is doing any upsampleing and or filtering. It was all the rage at the time.
wheras the data is travelling from the mac via wifi to the sb, and is then sent via the optical sender on the sb
Possibly simpiler, as much of that doesn't have to happen in real time, the sb can buffer, and the network stack can error correct and retry as needed.
perhaps some error correction in the sb to reconstitute the datastream from the wifi aerial and reject any noise on it
Its a lot more complex that that, there s the whole IP stack and associated code. Its not just taking a signal from the antenna and pushing it out the optical driver.
There is also the lms server software, which may be doing some jiggery pokery when it buffers the data to send the packets.
May be, but none of it should be altering the actual data. Assuming you are storing lossless and don't have any volume adjustment going on.
But still, surely the data the dac interprets should be nigh on identical to whats read off the disc in the first instance, or as near as possible...
Yep it should be...
Little known fact, coherent thought can destructively interfere with itself leaving no thought at all, that’s why I prefer incoherent thought.
Ant
Needs to get out more
Posts: 1650
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#25 Re: Dac for an arcam delta 170.3 transport

Post by Ant »

The cd rips are all apple lossless, and to be honest i dont know it the topping dac upsamples or reclocks. its their new one and is dsd 512 and 32/768 (i think) capable, and its set at a fixed output level so theres no digital attenuation going on. It can attenuate, but ive set it up so it doesn't

Fwiw, the sb is also set to 100 volume too so its not attenuating either

The dac has user selectable filters, again these havent been changed between the sb and the transport
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
JamesD
Old Hand
Posts: 894
Joined: Tue Oct 09, 2007 4:26 pm
Location: North Yorkshire

#26 Re: Dac for an arcam delta 170.3 transport

Post by JamesD »

Nick asked
What are you thinking that would do?
w.r.t. Wifi transmission of the audio signal...

Simply put - co-channel interference on the rf signal causing modulation errors on de-mod leading to bitstream corruption - I have some experience of this and I am aware that this description is a significant over-simplification given the ability of the wifi signal to negotiate and re-negotiate the bitrate,etc. not to mention the error-correction built into the different layers of the signal... however the existence of all these schemes to maintain the signal points to how much errors are introduced

Really just trying to think through what might cause the sort of bit-stream errors that result in the sound Ant describes...
User avatar
Nick
Site Admin
Posts: 13656
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#27 Re: Dac for an arcam delta 170.3 transport

Post by Nick »

Yep, but on top of the wifi stack will be a TCP/IP (or UDP) endpoint, so you should (will) get error free transmission or no data. The world as we know it would stop if there was errors in what comes out of a socket interface.
Really just trying to think through what might cause the sort of bit-stream errors that result in the sound Ant describes...
Was thinking about that, it should be possible to see if there is actual data difference (as opposed to timing errors) by using a sound card or DAW with optical input to compare the same data direct from CD or via a rip and streamer by capturing it to a WAV (or similar) file and then comparing the numbers. I don't know if Chris or Ed has something that would take a optical input to a WAV file. Something to think about if we ever leave our houses again.

If the numbers were different, it would prove that something was being changed. If they were the same what Ant was hearing must be down to the last link in the chain.

I remember doing something similar to compare the data from a CD via EAC and a simple copy and the result was there was no difference, the data was bit for bit identical when you removed leading and trailing silence.
Little known fact, coherent thought can destructively interfere with itself leaving no thought at all, that’s why I prefer incoherent thought.
Ant
Needs to get out more
Posts: 1650
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#28 Re: Dac for an arcam delta 170.3 transport

Post by Ant »

the thing that intrigues me is the fact that the difference is not subtle.
I was expecting a subtle difference, but not a marked difference i can point at.
A few years ago when i had the first sb and an apple tv, there was a subtle difference between the 2, and a subtle difference between those, and using the mac mini which was better again.
Granted, the mac and apple tv are not purpose built for audio, and the sb was never intended as the best thing since sliced bread, but the delta is 30 years old.....
arcam put their time and effort into the digital output board, thats what the point 3 bit is, and its stuffed full of black gates and that lovely cdm1 mk2 transport mech, and there are 3 separate power supplies in the thing, but as digital has moved on so much in 30 years i simply wasnt expecting what ive got out of it.
The other dead one never sounded as good as this one, i would point straight at the dac as the reason, as the last dac i used it with was a musical fidelity x24k. Which was new 20 years ago. Perhaps thats where the development has been focused as the use of an optical disc reader has nigh on disappeared in favour of hdd ssd storage
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
User avatar
ed
retired
Posts: 4709
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#29 Re: Dac for an arcam delta 170.3 transport

Post by ed »

too many variables!

I may have missed the subtle change in the direction of the discussion here.

and haven't we been over this, and then over it some more....Ant's original post was to do with the fact that this set up doesn't sound like the previous set up....or am I missing the premise here?????

We don't actually listen to the DAC itself, but more the surrounding circuits which are in the analogue area.

Sure the DAC has been changed but so has the circuitry feeding the DAC and the circuitry exiting the DAC...it's all part of the 'DAC' box that was bought.

My old analogue scope had a facility whereby you could measure both the input and output signals, invert one of them and then add them, after normalising them. The error was then plainly visible as a wave. I may have misunderstood this function due to ignorance but I loved the fact that it might have been doing what I thought it was doing. IMO this is the sort of test that could/should be applied to a new DAC unit, cos the bits in are more than likely going to equal the bits out.

So are the digits actually what is being discussed and criticised here?

edit: this may or may not have a parallel in the class d discussions that abounded when the tpa3116 was released: people were arguing about whether this board, with this chip was better tha this board with the same or different amp chip. What was obviously different was the implementation of the filters and surrounding circuitry, but the argument raged about which amp chip was better.
There's nowhere you can be that isn't where you're meant to be
Ant
Needs to get out more
Posts: 1650
Joined: Mon Jul 31, 2017 6:45 pm
Location: Yorkshire

#30 Re: Dac for an arcam delta 170.3 transport

Post by Ant »

The thing that i was commenting on is the fact that the squeezebox into the topping dac sounds fine, but the cd transport into the topping dac sounds different.

I was musing that the data being fed to the dac from the sb and the cd transport should be the same data, as the data that the squeezebox is sending, is a lossless cd rip from the very same cd that the transport is playing
So the sb and the transport should be sending the dac an identical datastream, so why does one sound better than the other?
If the dac is seeing the same data, via the same optical input and the same optical cable, then It 'should' sound identical irrespective of wether its the transport or the sb that is delivering the data to it
If the dac is seeing the same set of 1s and 0s, then it should do the same thing with them, which makes me wonder if theres some mechanism in the different transports (i suppose in this case both the sb and the delta could both be described as a transport) that is causing the difference
Before, i just thought that it was the dac that made the difference to sound quality, and when i had the original delta transport, i just stuck a different dac on it and it sounded better, worse, or different. Same with the sb, when i was using it before, stick a different dac on it and it sounded better, worse, or different.
This time its the other way around, as its the same dac, but different transports. Ive never had 2 different transports to compare and never considered that there would be any difference
Also starring Rex Hamilton as Abraham Lincoln

www.bte-designs.weebly.com
Post Reply