The DAC side of the force

[StanleyB]

You really need a good 48 hours of burn in before some of the previously hidden details start to be apparent. The bass also starts developing its firmness.
I used to have in my room one that had been through the burn in cycle for a while to compare one right out of the box. So visitors could hear the difference burn in makes.
For PC based music storage, the re-clocking and de-jitter circuit in my DAC can make even 128K mp3 samples sound quite respectable.
I always smile when I get emails from customers who comment on the fact that they can again hear details in their sampled music that they thought had been discarded by the ripping process. Many say it is impossible, and on one website I even got a thread dedicated to debunking the likelihood of it even been possible.
Ah, but who else ever used the PCM1716 to its full potential, let alone still uses that chip except for me ?

[leo]

Recently heard another dac using the pcm1716, heard a lot of units using those Not my unit BTW, belongs to somebody I know

[Emmodd]

guess i won't be making a snap decision tomorrow then lol. Will feed back...

[Mr. C]

Lots of upgrade scope on that dac guys.

[leo]

Just a shame that chip uses internal op-amps for the I/V
Have you tried the Wolfson equivalent to the pcm1716 Stan?

[StanleyB]

Just a shame that chip uses internal op-amps for the I/V
Have you tried the Wolfson equivalent to the pcm1716 Stan?

You say that about the I/V stage, but I disagree. I spent some time messing about with the PCM1798, which needs external opamps for the I/V process. Straight away, the output stage becomes highly complex. Even apparent simple things like what kind of feedback to use are critical. Tie that into the anti-aliasing filtering method available, and the analogue output stage ends up being a complicated and expensive part of the circuit. You can't get away with low cost opamps in a precision I/V design, which is what a I/V DAC analogue circuit needs. But have you seen how much 4 pieces of OPA627 can set you back?

Chips like the PCM1716 allows for alternative output designs that are far less complex and that can be dirt cheap to implement. One of them is to have a zero opamp output. But the signal is too low at 0.6V for CD inputs on amps.

The funny thing is hat the PCM1716 was redesigned in 2005 in order to conform to RoHS. I use the new version in the TC-7510, but I used the old version in my previous DAC, the TC-7500. The differences between the two are miles apart. The new chip needs a lower soldering temperature in the soldering bath, but modern lead free solder needs a higher temperature. On the 1st production run of the TC-7510 we ended up writing off more than 300 boards before we got the hang of how to handle the new chip. It was a huge expense that nearly put me out of business. But I stuck with the chip, because I discovered that the RoHS version of the PCM1716 was more musical and had more detail than the older version.

I tried the Wolfsson replacement of the PCM1716, the WM8716. I even have a modded version of my DAC fitted with one. It has a higher output, but sound wise I can't pick up any more detail than I get out of the 1716. It is also twice as expensive at the factory gate. If you run that down the food chain all the way past import duties and the VAT man, it would add £15 to £25 to the DAC retail price. I am in a price sensitive region, so I leave that to the modders.

[leo]

Of course you disagree, I wouldn't expect a manufacturer to use a chip requiring a complex output stage and then selling the thing for less than 200 quid, it wouldn't be worth it, it was just an opinion from somebody who likes to fiddle
Also please don't think I'm picking or anything at your dac, I commented in another thread I've already heard it and said it was good for the price.

The pic of the dac above costs several times the price of the TC-7510, is it worth it? I didn't think so after listening to it.
Soon as I hear something that beats my diy TDA based dac (as long as the price isn't stupid) I'll gladly buy it and even post my opinion on here

Only op-amp I've heard which is good for an I/V stage is AD844 but the reason for that is because it can be implemented as a common base, its one of the few chips that allows you to tap into it, it sounds pretty poor when implemented as the classic op-amp I/V and also needs DC nulling on the input.
Best I/V stage I used is totally discrete, its complex , needed to be matched, obviously costs more and takes more space but to me is the best I've tried so far, these things don't really matter when your into diy.

I personally do not like OPA627AP or the BP grade, they sound fake to my ears used with voltage out dacs or as I/V , adding a CRD to the output to the supply pin with worse PSRR helped but I still didn't like it, infact I don't like many J-fet input based op-amps , some of the AD ones are not too bad especially if the design requires something to be run from a single low supply

I know a lot people where ROHS caused them grief

[leo]

BTW I've not tried the so called Wolfson upgrade to this chip, I just wondered if you'd tried it

The WM8741 isn't a bad chip either, like most newer devices its differential output though, itsalso supposed to use switched caps for the internal I/V

[Peter Stockwell]

For PC based music storage, the re-clocking and de-jitter circuit in my DAC can make even 128K mp3 samples sound quite respectable.
I always smile when I get emails ...

I'm listening to internet radio at 128Kbps, and without turning the tuner to the same station to compare, I can't say that it's worse.

It's damn good in fact. The tuner is definitely moving out!

I'm reserving judgement on the CD player, 'cause, got visiters in and I can't listen at normal levels to make a good comparison.

cheers

[StanleyB]

Also please don't think I'm picking or anything at your dac,

It never even crossed my mind.

BTW I've not tried the so called Wolfson upgrade to this chip, I just wondered if you'd tried it

Yep. Get on the Wolfsson website and register for a sample of the chip. All you need to do is use a sharp Stanley knife and press down on each leg of the chip right next to the body of the chip. Don't try to cut the legs like you would cut a piece of paper!!! Just press down, and each leg will cut off. Whip the chip out, run the hot iron over each cut leg, and they'll lift off.
If you ever get to do this mod, contact me before you switch on the DAC again. There are two pieces of wires that need to be soldered to the circuit.

I have a Stage-1 mod for the output stage that I charge £30 to do. But anyone competent enough can do it just as easily. Email me for the diagram. No parts required, except for 4 pieces of stiff single strand wire of less than 1mm. I use the ends of a resistor...
The Stage-2 needs 2 caps replaced, but is more suited to 12" bass listening. Makes my NS1000M sound like a new set of speakers.