I just received my Wolfson 4.0 BIY DAC :)

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#61
marchel said:
Hi Erin, Thanks,

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BTW, I found some time to take photo of the dac again, While it is open, I guess I really like taking photos, LOL.

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Cool housing, where did you get that?
albert
 
#64
I just received mine 🙂

I think there has been a few slight differences compared to marchel's. For one, it came with opa604 instead of the opa134 reported by others.

First impressions are real nice so far, but it's still breaking in. The fit and finish is beautiful and it was well packed, although there is one stripped screw hole, which made removing one of the screws a PITA.
The case exceeded all my expectations. It's thick, robust, and has a beautiful brushed finish. (I expected the black part to be regular painted black steel seen in the usual cheaply made enclosures.)

Thus far, I (ever so slightly) prefer USB over coax (from my creative x-fi soundcard.) Any one tried coax or optical with a good usb to spdif transport yet?

By the way, can anyone tell me how much of a difference upgrading to the opa627 will make?
 
#65
I've never heard it with the stock OPA134 or OPA604, but the OPA627 goes really well with it. It gives my ESOUND cd player a run for its money, but to be honest it lacks just a bit of detail (hence ppl might say it sounds "tubey" ha!).

Anyway, another option may be the LME49710....cheaper and probably more neutral.
 
#67
lordearl said:
I've never heard it with the stock OPA134 or OPA604, but the OPA627 goes really well with it. It gives my ESOUND cd player a run for its money, but to be honest it lacks just a bit of detail (hence ppl might say it sounds "tubey" ha!).

Anyway, another option may be the LME49710....cheaper and probably more neutral.
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Hi Lordearl,


You can try the ad797 to replace the four IC's near the WM8740 chips, It seems to me that the ad797 is very good at extracting details from the source, But not very good or not as good as the opa627 or the stock opa134 at driving linestage.

I just recently found this out when I replaced the two output stage ad797 with the stock opa134, The combination is more dynamically effortless than using the ad797 alone.

So now I just bought a pair of opa627 to be placed in the output stage, I've yet to receive them. With the four ad797 in the filter stage, This combination should be interesting, I'll report back when i take a good listen at it. 🙂
 
#70
I'd have to agree that it does "lack" a bit of detail compared to my old DAC. Well, at the very least, I find that some of the details are harder to "pick out" and can get "muffled" by the rest of the music. However, I also feel (read: subjective) the Wolfson is more accurate and more enjoyable for most albums.

Please do keep us updated regarding the AD797 + OPA627 combo! I'm very interested.
 
#71
MX2 - glad you agree with my thoughts!! Also shows that the upgrade to 6x OPA627 may not be worth the $$$.

I have just followed Marchel's lead and ordered some different opamps for the output stage. I'm trying 2x BUF634 - should be very interesting given that they are unity gain stable.
 
#74
mx2 said:
I'd have to agree that it does "lack" a bit of detail compared to my old DAC. Well, at the very least, I find that some of the details are harder to "pick out" and can get "muffled" by the rest of the music. However, I also feel (read: subjective) the Wolfson is more accurate and more enjoyable for most albums.

Please do keep us updated regarding the AD797 + OPA627 combo! I'm very interested.
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Hi Mx,

Have you tried to bypass the resistor in the output, Cause it's gonna open up the sound a bit.

In my unit , I don't feel it's lacking in details, Due to the ad797 I use, The detail retrieval difference between this opamp and the stock opa134 is big and very noticeable. Though ,Using ad797 exclusively, I feel that the sound is too analytical in the long run , This why I bought the opa627 for the output stage, cause I feel that it's gonna balance the sound.


781W0041-2.jpg
 
#75
hi

Since this device is prepared for balanced output. You may get an improvement in sound quality, by omitting the output stage completely.
I mean the holes are allready in the board. Just connect the positive and the gnd to the output RCA's and forget the negative. That way you get a much shorter signal path.

I don't have this dac, but this exact "trick" does work on the Cambridge DacMagic. It does sound better on the balanced output, because it doesn't have to go through that extra output buffer opamp.

It's just an idea 😛

I would try it if it was mine😀
 
#76
but without both poles you arent getting balanced output, there is no possible way that could improve on just taking it from anywhere. thats a rather confusing suggestion, the 'output buffer' is also combining the 2 poles, so is summing the output, meaning you get most of the dynamic range of the balanced output. doing it your way you only take half the balanced out, so would actually suffer from LESSER quality output, the dynamic range and THD would be significantly impacted
 
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#77
I don't know exactly how this dac is build, but very often the balanced output has double the output of the single ended. So taking the pos. and gnd gives you enough output. But that can be different here, i don't know.
But I doubt that adding extra opamps will improve quality. It might give a higher output voltage, but that is not a quality in it self. Many modern systems have way too much gain, so unless you use your dac without a preamp, you don't need that extra voltage.

But again, as I said earlier. It's just an idea, and it works on my DacMagic.

No hard feelings. ;-)
 
#78
Or use a line to line transformer (1:1 600 ohm typically) to convert balanced to unbalanced. I do this and find it more transparent than the LM4562 active circuit it replaced in my BB PCM1794A based dac. I recommend 25 to 75 ohm resistors in series with the buffer outputs prior to the transformer primary.

Suitable transformers include UTC A-20 and A-21 amongst others and I am pretty sure that Lundahl makes something that will work as well or better. Lots of transformers to try..

Try it, you'll probably be as surprised as I was...
 
#79
kevinkr said:
Or use a line to line transformer (1:1 600 ohm typically) to convert balanced to unbalanced. I do this and find it more transparent than the LM4562 active circuit it replaced in my BB PCM1794A based dac. I recommend 25 to 75 ohm resistors in series with the buffer outputs prior to the transformer primary.

Suitable transformers include UTC A-20 and A-21 amongst others and I am pretty sure that Lundahl makes something that will work as well or better. Lots of transformers to try..

Try it, you'll probably be as surprised as I was...
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Thanks for this suggestion, This is a very good suggestion, I was thinking about this, But then The transformers might not fit , And I don't want to change the outside appearance or the portability of this DAC, By adding outboard transformers., I'm also afraid that it might mellow the sound a bit, But how would I know that if I don't try it 🙂 , I'm also thinking about discrete op amps, But to be honest though, The dac already sounds very good in it's current state.
 
#80
Noise said:
I don't know exactly how this dac is build, but very often the balanced output has double the output of the single ended. So taking the pos. and gnd gives you enough output. But that can be different here, i don't know.
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enough yes, but no difference at all to using the + from before the last opamps, again, its not balanced....unless its balanced......

half a balanced output is simply a whole single ended output. but in this case the last opamps combine the +/- outputs as a summing stage as well as a line driver/buffer. so by skipping this step you miss a LARGE amount of the performance

But I doubt that adding extra opamps will improve quality. It might give a higher output voltage, but that is not a quality in it self. Many modern systems have way too much gain, so unless you use your dac without a preamp, you don't need that extra voltage.
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I dont think you know what is going on here, in fact the last stage includes the output setting resistors, so the output will be hotter without it, but we arent talking about loudness, without the summing stage, there is the above mentioned DNR and THD performance missing, but also you miss out on ALL the CMMR which cancels a large amount of the noise (more loss in dynamic range and more self noise


But again, as I said earlier. It's just an idea, and it works on my DacMagic.
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but is there any similarity at all between the 2 circuits? I doubt it, this circuit is actually quite novel, but regardless if you simply take half the balanced output as your SE output in your dac magic, you are doing the same thing and skipping on the performance of a differential IV conversion stage, which is realized when the 2 poles are summed in the last opamp.

I repeat; half a balanced output has nothing at al in common with a balanced signal

No hard feelings. ;-)
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sure absolutely, I dont even own one of these dacs 😉, no problem man, i'm glad you like the sound of your system and the subjective gains in sound quality from this mod. It sounds to me like you need to do some reading, as i'm not sure you quite understand the concepts you are playing with; no offense intended, but you will get more out of purposeful mods specific to the circuit you are modding, you cannot apply a blanket mod and expect to gain improvement (other than 'subjective' improvement) in a completely different circuit.

I know its rather fashionable here in some circles to think that no opamp is a good opamp and I actually prefer discrete circuits in general too, but you cant just take away an important part of the circuit like that without replacing it with something that achieves the same goal and get the same or better results. that and there are some things that are just far easier to achieve with an opamp; low output impedance being one of them.

peace

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I suggested transformer coupling much earlier in the first few pages I think, the fairly high voltage output is perfect for it, but you will have to keep that in mind or you will saturate the transformer with an input that is too hot.

the O-Netics trannies are nice, with good performance and small size. there are trade-offs, but its really a pretty elegant way to go, simple circuit, with low parts count, galvanic isolation and take your pick of balanced or SE output with no extra parts. usually higher distortion and lower bandwidth tho
 
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