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georgehifi

Holo Spring Dac (level2) review.

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1 hour ago, Sir Sanders Zingmore said:

Same goes for Sabre DACs of course?

Same also goes with positive opinions....

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4 hours ago, gonefishing999 said:

What dacs have you tried to make this comment?

Have you tried the Holo?

Peter

Hi Peter, 

I started off over 10 years ago with:

TeraDac 8xTDA1543 NOS

 

Then...

Analogmetric TDA1541 NOS

 

Then

Raindrop Hui 2x TDA1541 NOS

 

Then

Hifi DIY TDA1541 NOS with 6922 valve output stage. 

I lived with this one for about 6 years. I loved it at the time.

 

Also tried Raindrop hui 2x  PCM58 NOS. Also very nice. I still have it! I actually like it more than all the other TDA1541 DACs. 

 

I'm an electronics technician, so they all had various small modifications which I think improved the sound over the stock units.

 

With all of these NOS DACs when I (or anyone) looks at a NOS DAC playing sine waves on an oscilloscope, when the sine wave frequency playing is around 8Khz -10Khz you start to see distortion. When the sine wave is about 14Khz and above, the sine wave looks nothing like a sine wave at all. It's a mess.

 

This is because the output stage requires a high order brick wall filter to remove the 44.1khz sampling frequency to prevent aliasing. But none of these DACs have a brick wall analogue filter. This is why oversampling was introduced, to move the sample rate higher so a lower order filter could be used. 

 

Like I said earlier, I don't notice it too much on rock/pop, but with orchestral music I do notice it.

 

You can use software to upsample the the file to 176.4khz (4x oversampling) to avoid the output stage distortion issues when using a NOS DAC. 

 

So It's not the end of the world.

 

No, I haven't heard the Holo spring, but no literature has said they use a brickwall filter so I expect this DAC has the typical technical issues of all the other NOS DACs.

 

My comment was was not a criticism of the Holo, rather a comment about what I hear when listening to NOS DACs in general.

 

For what it's worth, I really do like what NOS DACs do in the low and mid frequencies.

Edited by eltech
Corrected mathematical error

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@eltech I think it's time you tried a Holo

If you live in Melbourne you can hear mine.

You put it on your oscilloscope and lets see the results .

47 minutes ago, eltech said:

My comment was was not a criticism of the Holo, rather a comment about what I hear when listening to NOS DACs in general.

That's why i asked the question.

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4 minutes ago, gonefishing999 said:

@eltech I think it's time you tried a Holo

If you live in Melbourne you can hear mine.

You put it on your oscilloscope and lets see the results .

That's why i asked the question.

Happy to if you're anywhere near Croydon.

 

This may sound flippant, but I was one of the people singing the praises of NOS DACs on fora over 10 years ago when they were mostly something for hobbyists, not mainstream.

 

I know what they do well, and what they don't. Going by all the reviews and comments, I have every reason to believe this unit is subjectively excellent. (For a NOS DAC)

 

If there is anything to say Holo has solved the distortion issues when playing 44.1khz audio then please direct me to that literature.

 

Otherwise that distortion will be there on the scope.

 

The quality of the components, the excellence of the power supply ripple, the niceness of the output stage transistors etc. won't change anything to do with this. It's a technical problem of the NOS typology.

 

Edited by eltech

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1 hour ago, eltech said:

No, I haven't heard the Holo spring, but no literature has said they use a brickwall filter so I expect this DAC has the typical technical issues of all the other NOS DACs.

It does ....  but is the audibility of them overstated (!?)

 

You'd have to consider correcting for the non-flat frequency response ....  but the ~0.3% "THD" might not be a worry.

 

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16 minutes ago, eltech said:

Especially read the comments by miska half way down.

He's spot on .... the only thing is whether these things are very audible in a purely playback system..... but they do seem undesirable (even for simple playback), and can be avoided, so  +1

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55 minutes ago, davewantsmoore said:

He's spot on .... the only thing is whether these things are very audible in a purely playback system..... but they do seem undesirable (even for simple playback), and can be avoided, so  +1

You could ask that question about DAC

differences in general 

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11 minutes ago, Sir Sanders Zingmore said:

You could ask that question about DAC

differences in general 

The answers to such general questions might be unlikely to be really helpful.

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8 minutes ago, davewantsmoore said:

The answers to such general questions might be unlikely to be really helpful.

Depends on how you define “helpful”. 

For me, realising that DAC differences are far less than we are led to believe was incredibly helpful. 

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3 minutes ago, Sir Sanders Zingmore said:

Depends on how you define “helpful”. 

For me, realising that DAC differences are far less than we are led to believe was incredibly helpful. 

Your Room could have a big effect, what you have in the rest of the system (speakers, etc) could also factor in why you thought they were very similar too.

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3 minutes ago, rocky500 said:

Your Room could have a big effect, what you have in the rest of the system (speakers, etc) could also factor in why you thought they were very similar too.

Sure, but it’s not an isolated experience. Switching between the same DACs at a number of friends’ places (all with very good and very different systems) yields consistent results. 

 

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1 hour ago, davewantsmoore said:

 

It does ....  but is the audibility of them overstated (!?)

 

You'd have to consider correcting for the non-flat frequency response ....  but the ~0.3% "THD" might not be a worry.

 

Hi Dave, my personal experience is that I could hear it, and once I did, I couldn't un-hear it. But, generally I think it's not that audible or important on many types of music, but when doing AB comparisons of OS vs NOS DACs on especially orchestral music I can hear it, and after I was able to learn the characteristic sound of NOS, and hear where sounds became unclear (and murky) at certain frequencies it did become overtly obvious and important to me.  But I know that some people won't notice it, and even if they do, they won't care because there are other virtues to the sound of NOS DACs. It's a personal thing.

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1 minute ago, Sir Sanders Zingmore said:

Sure, but it’s not an isolated experience. Switching between the same DACs at a number of friends’ places (all with very good and very different systems) yields consistent results. 

 

I agree that Dacs lately are all getting very good. I still seem to get that bit more enjoyment and drawn in from certain ones even though they are as you say are very close these days.

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Just now, rocky500 said:

I agree that Dacs lately are all getting very good. I still seem to get that bit more enjoyment and drawn in from certain ones even though they are as you say are very close these days.

I also think modern DACs are getting very good. Still prefer my OS R2R because of its great dynamics and detail. But not passionate about it anymore. If something comes out tomorrow that beats it, then good, I'll buy it irrespective of typology. I want sound quality to improve because thats a good thing.

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16 minutes ago, Sir Sanders Zingmore said:

Sure, but it’s not an isolated experience. Switching between the same DACs at a number of friends’ places (all with very good and very different systems) yields consistent results. 

 

I'm with you. At a certain level, most good DACs are very good. The differences people mention are quite minor, and people are quibbling about very minor differences of which nothing should be a deal breaker.

When comparing a low grade older DAC to a top notch new DAC there are some obvious differences in detal, dynamics and naturalness.

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1 hour ago, Sir Sanders Zingmore said:

Sure, but it’s not an isolated experience. Switching between the same DACs at a number of friends’ places (all with very good and very different systems) yields consistent results. 

 

I actually bought a Topping D50 Dac after your comments of a Topping Dac and Holo shootout you had.

Hoping I might sell the Holo and spend the extra money on something else.

The Topping is a nice Dac but does not draw me in like the Holo Dac. The Holo to me really is a lot more enjoyable and love late night listening with it, while I tend to use to topping now for background listening as I can lower the volume. My system at its lowest volume is quite high already.

Maybe its something with R2R Dacs, but I am hooked and can't seem to get the same enjoyment from the others.

I do use a modded Singxer playing from a PC to connect both dacs. I also have a nice Linear power supply on the Topping.

Edited by rocky500

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2 minutes ago, rocky500 said:

Maybe its something with R2R Dacs, but I am hooked and can't seem to get the same enjoyment from the others.

You've seen the light and heard the benefits, I love it also, because I don't listen to dsd or sacd.

It's "said" by higher powers than anyone here, only an R2R Multibit dac can convert PCM 16/44, 24/96 or DXD bit perfect, any other form of conversion of these is said to be a facsimile, and not bit perfect.

 

Cheers George

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59 minutes ago, georgehifi said:

It's "said" by higher powers than anyone here, only an R2R Multibit dac can convert PCM 16/44, 24/96 or DXD bit perfect, any other form of conversion of these is said to be a facsimile, and not bit perfect.

That's only true for NON oversampling DACs of the R2R variety. But as discussed earlier, unless the data is oversampled or upsampled you will get distortion on the output and that isn't the same as what went into the ADC. You need to look at the analogue output of the DAC to judge it, not merely by its data conversion. One advantage of NOS DACs (including at least one delta sigma DAC which can be put into NOS mode) is that they can reproduce square waves which I think is an advantage for playing certain music using synthesizers. But, it's a limited benefit because not much music at all uses pure square waves. It's just a win on technical grounds.

 

The main and only issue I have with Delta sigma DACs is that they can have a slightly hissy sound behind transient signals which I hear on every delta sigma DAC that I've heard. But ESS has done some work on this area and reduced this noise considerably, however I still hear it sometimes. R2R doesn't have this issue at all.

 

So what I hear on Delta Sigma DACs is that if I'm listening to a snare drum I hear something like a pre echo that goes hiss, (crack of the snare drum) then hiss. This is of an incredibly short duration. But I hear it.

A snare drum played back on an R2R DAC just goes crack! With no pre or post hiss.

 

Even though older r2r dacs used oversampling chips they were designed to simply multiply the sample rate by 4 times and interpolate (smooth out and join the dots) the samples in between the samples to create a more accurate analogue output, as well as using an algorithm to attenuate the spurious signals which are over 22.5Khz.

Mathematically what went into the ADC in the analogue domain, is what comes out of the DAC in the analogue domain. Minus the spurious out of band noise.

Edited by eltech

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Delta Sigma dacs operate a little bit like VW diesel engines in the dieselgate scandal. The Delta Sigma DAC can reproduce a sine wave perfectly under test conditions but in real-world conditions of playing music they have little errors. Edit. Actually I don't think they have errors I think the bits come out at the right time and amplitude it's just that they seem to have a bit of a noise in addition to the signal and I'm not sure if it's part of the Delta Sigma modulator or if it's something to do with the op amp. It could be a bit of both.

Edited by eltech

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