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Izotope SRC


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Hi Jud,

 

Over at SRC Comparisons have a look at the "Passband" or "Transition" test results for iZotope Rx Adv 2 (High Steepness) compared to Sonic HD for the same test. In fact, compare iZotope Rx Adv 2 (High Steepness) on those tests to any other SRC listed. The results aren't shoddy for iZotope Rx Adv 2 (High Steepness) on any of the other listed tests either, but those two test results are just visually impressive even to a layperson like me.

 

If I'm not mistaken, the "Sonic HD" on the infinitewave site is the old Sonic SRC, not the latest one.

They offered iZotope's SRC for a while, fulfilling a wish of mine, after Sonic HD and before their latest.

(I have not yet had a chance to compare the latest with iZotope's.)

 

Best regards,

Barry

Soundkeeper Recordings

The Soundkeeper | Audio, Music, Recording, Playback

Barry Diament Audio

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Over at SRC Comparisons have a look at the "Passband" or "Transition" test results for iZotope Rx Adv 2 (High Steepness) compared to Sonic HD for the same test. In fact, compare iZotope Rx Adv 2 (High Steepness) on those tests to any other SRC listed. The results aren't shoddy for iZotope Rx Adv 2 (High Steepness) on any of the other listed tests either, but those two test results are just visually impressive even to a layperson like me.

 

High Steepness for isotope RX Adv 2 is indeed an impressive result in the context of this test, because it practically corresponds to an "ideal" filter.

 

Is that really comparing like with like though? Sonic HD has a "Steep" filter; but not a 'High Steepness" filter. The fact that iZotope has more possibilities, is perhaps, by itself a reason to regard it as the superior re-sampler.

 

Then again how do these options work out in actual listening tests? I for one certainly preferred several of the re-sampled files I prepared with iZotope. Notice that iZotope 64bit steep is also pretty close to an ideal filter and better than Sonic HD's steep filter, so perhaps that is more of a "like with like" comparison.

 

Graphically, at least, iZotope appears to win, judging by this test. Though I'll admit to not being qualified to fully interpret the results.

Owner of: Sound Galleries, High-End Audio Dealer, Monaco

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  • 1 month later...
  • 2 months later...

hey all i am not an "audiophile" per se rather an audio mixing engineer. i do however have a question which references this thread.

 

i just purchased sample manager which has the izotope 64 bit src in it. i am trying to upsample a bunch of 24 bit wav files from 44.1khz to 48khz for the sake of unifying the sample rate of a mix session i am working on where half the files are 48 and the other half are 44.1..

 

however i am not sure what the most ideal upsampling settings are for "filter steepness" "cutoff scaling" and "pre ringing"

 

i do not understand the pure science behind nyquist and all that stuff despite trying to read it so i would appreciate some help

 

thanks

 

aram

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hey all i am not an "audiophile" per se rather an audio mixing engineer. i do however have a question which references this thread.

 

i just purchased sample manager which has the izotope 64 bit src in it. i am trying to upsample a bunch of 24 bit wav files from 44.1khz to 48khz for the sake of unifying the sample rate of a mix session i am working on where half the files are 48 and the other half are 44.1..

 

however i am not sure what the most ideal upsampling settings are for "filter steepness" "cutoff scaling" and "pre ringing"

 

i do not understand the pure science behind nyquist and all that stuff despite trying to read it so i would appreciate some help

 

thanks

 

aram

 

I am not an expert, but I do have familiarity with the Sample Manager software, having owned it for a couple of years, and having upsampled hundreds of redbook CD's. I also use Audirvana Plus, which has custom settings for its built-in Izotope SRC, where you do hear the effect that slight adjustments make.

 

If you are willing to take the advice of an anonymous, self-described non-expert, I would suggest this. The jump from 44.1 to 48kHz is pretty minimal regardless, so I would set the steepness at 10%-20% on the scale, Nyquist cutoff at 1.00, and pre-ringing at .90 to 1.00. This will achieve what you are trying to do, without changing the sound mix appreciably.

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I am not an expert, but I do have familiarity with the Sample Manager software, having owned it for a couple of years, and having upsampled hundreds of redbook CD's. I also use Audirvana Plus, which has custom settings for its built-in Izotope SRC, where you do hear the effect that slight adjustments make.

 

If you are willing to take the advice of an anonymous, self-described non-expert, I would suggest this. The jump from 44.1 to 48kHz is pretty minimal regardless, so I would set the steepness at 10%-20% on the scale, Nyquist cutoff at 1.00, and pre-ringing at .90 to 1.00. This will achieve what you are trying to do, without changing the sound mix appreciably.

 

thanks anyone else care to chime in?

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  • 3 weeks later...

I feel the need to bump this thread for anyone who hasn't seen it.

 

These Izotope settings are fantastic and really invaluable for dialing in ones dac. I've been playing around with the settings for the last couple of weeks, and I've finally settled on a combination that is pushing all the right buttons. My dac is PCM1704UK based and I've disabled the dsp, so running NOS. Very happy! I haven't listened to vinyl in over a week, which is highly unusual for me.

 

My settings for anyone interested are: Steepness 3 / FML 2,000,000 / CF 1 / AA 200 / PR .99

 

Makes me wish I still had some of the older dacs I've long since sold off.

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My settings for anyone interested are: Steepness 3 / FML 2,000,000 / CF 1 / AA 200 / PR .99

 

Makes me wish I still had some of the older dacs I've long since sold off.

 

zxzyx: Thanks for bumping the thread. So glad you are enjoying the fruits of digital filter tuning with the advanced iZotope settings in A+. Indeed, a well tuned DF can take turn a decent DAC (good clocking, good PS and output stage) into a mind-blower. I have done this on several occasions with DACs that had not earthly right to sound as good as they did when we got done.

Are you able to run at least 176.4 into your DAC? I assume that you are staying with "power of 2" upsampling. Can you use Integer Mode? Are you using Mavericks? I too use an NOS PCM1704.

 

You might try pulling the Filter Max Length down to about 1,300,000 and see what you think. It's subtle, but try it with piano.

 

If you feel like it, tell us about your system.

 

Best,

ALEX C.

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Are you able to run at least 176.4 into your DAC? I assume that you are staying with "power of 2" upsampling. Can you use Integer Mode? Are you using Mavericks? I too use an NOS PCM1704.

 

Hi Alex,

I was under the impression 96 was as high as I could go with the PCM1704. I don't get any sound when I go over 96, which is why I upsample to 88.2 only. Honestly, I'm quite happy listening at 44.1...the soundstage shrinks a bit but is slightly more vivid overall.

 

My digital set up as it's currently configured: Pi Audio power conditioning --> 2010 Mac Mini / SSD / 8gb ram / Mavericks --> iFi iUSB / Gemini usb cable / Audiophileo 2 / Audio Gd Reference 7.1 Dac --> Mystere CA21 Preamplifier --> nCore monos --> Ohm Walsh 5000 speakers

 

Later tonight I'll try scaling back on the filter max length. It's worth a try because it's the slider I explored the least.

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Hi Alex,

I was under the impression 96 was as high as I could go with the PCM1704. I don't get any sound when I go over 96, which is why I upsample to 88.2 only. Honestly, I'm quite happy listening at 44.1...the soundstage shrinks a bit but is slightly more vivid overall.

 

My digital set up as it's currently configured: Pi Audio power conditioning --> 2010 Mac Mini / SSD / 8gb ram / Mavericks --> iFi iUSB / Gemini usb cable / Audiophileo 2 / Audio Gd Reference 7.1 Dac --> Mystere CA21 Preamplifier --> nCore monos --> Ohm Walsh 5000 speakers

 

Later tonight I'll try scaling back on the filter max length. It's worth a try because it's the slider I explored the least.

 

Well your Audio Gd DAC spec sheet says it is limited to 24/96 via its S/PDIF input, but the PCM1704 chip itself has no such limit. I run it at 176.4/192KHz and soon will have it going at 352.8/384KHz.

 

The bigger question is triggered by what you just said about listening just at 44.1: What button do you have selected in A+ for upsampling? If you have "None" checked, then guess what, all those adjustments you have been making with the iZotope settings have been doing exactly nothing! They are only for the filters of the sample-rate-conversion engine. Try setting it to 2X or "Powers of 2"--either will take you to 88.1KHz and then your settings will have an effect.

 

Ciao,

AJC

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If you have "None" checked, then guess what, all those adjustments you have been making with the iZotope settings have been doing exactly nothing! They are only for the filters of the sample-rate-conversion engine. Try setting it to 2X or "Powers of 2"--either will take you to 88.1KHz and then your settings will have an effect.

 

Hi Alex, I'm aware of that, It appears I deleted the middle of my first paragraph when posting. I was trying to say I prefer the pcm1704's in NOS mode more than using the dac's dsp.

 

I've been running with "oversampling 2 x only" selected in Audirvana...so 88.2kHz which has taken the playback to another level. I've also tried 96kHz to good effect. I am using the S/PDIF which explains why I can't go above 96kHz.

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Hi Alex, I'm aware of that, It appears I deleted the middle of my first paragraph when posting. I was trying to say I prefer the pcm1704's in NOS mode more than using the dac's dsp.

 

I've been running with "oversampling 2 x only" selected in Audirvana...so 88.2kHz which has taken the playback to another level. I've also tried 96kHz to good effect. I am using the S/PDIF which explains why I can't go above 96kHz.

 

Got it. Sounds good. As I recall, Kingwa lets you turn off the oversampling/digital filter entirely (have to open the top and set switches or jumpers). Is this what you do? Otherwise the DAC is taking the 88.2KHz you give it and doing SRC on that. Might sound good, but I think you will hear more of the 1704 and A+/iZotope if you disable the DSP entirely. While you are in there, you might also disable the dithering level control (assuming you have not already done so) since you use an analog preamp.

 

Have fun,

Alex

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Dithering level control? I've done nothing with that. I'll have to open the beast tonight and have a look.

 

I don't really know. I was just going by the 6moons review of that model which I skimmed to refresh my memory about that particular Audio Gd DAC. He has been so prolific over the years with so many models. All a great value. I wish I could buy R-core transformers for what he must get them for there in China!

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My settings for anyone interested are: Steepness 3 / FML 2,000,000 / CF 1 / AA 200 / PR .99

 

Makes me wish I still had some of the older dacs I've long since sold off.

 

zxzyx: Thanks for bumping the thread. So glad you are enjoying the fruits of digital filter tuning with the advanced iZotope settings in A+. Indeed, a well tuned DF can take turn a decent DAC (good clocking, good PS and output stage) into a mind-blower. I have done this on several occasions with DACs that had not earthly right to sound as good as they did when we got done.

Are you able to run at least 176.4 into your DAC? I assume that you are staying with "power of 2" upsampling. Can you use Integer Mode? Are you using Mavericks? I too use an NOS PCM1704.

 

You might try pulling the Filter Max Length down to about 1,300,000 and see what you think. It's subtle, but try it with piano.

 

If you feel like it, tell us about your system.

 

Best,

ALEX C.

 

The recent activity made me go back and take a look at (or rather a listen to) filter max length, which I hadn't bothered with before. I feel more than a little silly coming out with such a precise number, but after repeated listening to a range of material, a filter max length of 1,265,000 sounds right to me with my setup. For 44.1 material, I also slightly prefer oversampling at max (for me 384kHz) to powers-of-2. Gave me more of the guitar-strumming sound from the 2009 remastered mono "I'm Looking Through You," for example.

 

I know, both of these are kind of crazy talk, probably ludicrous even to think I can hear a difference between 1,265,000, 1,260,000, and 1,270,000, but that was right where the sweet spot seemed to be for me. This isn't nearly night-and-day stuff, and I seriously doubt I'd pass a DBT, though I sure am enjoying the music.

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

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  • 1 month later...
zxzyx: Thanks for bumping the thread. So glad you are enjoying the fruits of digital filter tuning with the advanced iZotope settings in A+. Indeed, a well tuned DF can take turn a decent DAC (good clocking, good PS and output stage) into a mind-blower. I have done this on several occasions with DACs that had not earthly right to sound as good as they did when we got done.

Are you able to run at least 176.4 into your DAC? I assume that you are staying with "power of 2" upsampling. Can you use Integer Mode? Are you using Mavericks? I too use an NOS PCM1704.

 

You might try pulling the Filter Max Length down to about 1,300,000 and see what you think. It's subtle, but try it with piano.

 

If you feel like it, tell us about your system.

 

Best,

ALEX C.

 

Hi Alex,

 

I wonder what your thoughts on upsampling are given the new DACs like Chord Hugo, PS Audio DirectStream, and the upcoming Bottlehead DAC.

 

better to just let the DAC have it?

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Hi Alex,

 

I wonder what your thoughts on upsampling are given the new DACs like Chord Hugo, PS Audio DirectStream, and the upcoming Bottlehead DAC.

 

better to just let the DAC have it?

 

As always, it comes down to whether someone is able to tune iZotope to sound better than the DAC's filter. Each of the new DACs you mention use an FPGA for various purposes--including running their own custom SRC/DF. It would take an enormous FPGA (vastly larger and more expensive than what any current DAC is using) to build filters with as many taps as can easily be had via s/w on CPU, but that in itself does not mean an advantage.

 

DF in software?, in hardware?--I don't think it really matters since it is all code anyway. To me it comes down to how careful the DAC's filters were designed.

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Can someone with LIO-8 dac post me their latest Izoptope SRC setting please ?

TIA

I'm using the ULN-8 with settings I found in a thread here.

 

I can't recall the poster, but it's one of those guys that's spent a lot of time tinkering. I recall one comment he made about thinking these settings were very DAC/system dependent, until he heard them on multiple systems and had positive feedback from others.

 

I had tried other settings people posted, as well as some tweaking of my own, but these have been the best for me.

 

Steepness: 7

Filter max length: 1,300,000

Cutoff freq.: 1.02

Anti-aliasing: 200.0

Pre-ringing: .86

 

I have it set to Maximum sample rate upsampling

 

Using version 1.5.10

 

If you try these, I'd appreciate your feedback.

Hackintosh W7/OSX 3570k/16GB > Audirvana+ > Metric Halo ULN-8 > Rythmik F12 and Butler Audio TDB 2250 > Magnepan 1.7 > 13.5'x26'x7.5' room, HK/Limage setup

 

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Bingo!

 

"DF in software?, in hardware?--I don't think it really matters since it is all code anyway. To me it comes down to how careful the DAC's filters were designed."

 

Very well said Alex. The fact is, that digital filter design is always a compromise (at least for sample rates below 352.8/384). There is no one "correct" digital filter, which will give "perfect sound" no matter how many taps one uses. So it will come down to a question of what digital filter one prefers in their system, to their ears. Since there are an infinite number of possible filter coefficients, at some point, an audiophile is going to have to decide what is "good enough" for them and enjoy listening to music, rather than futzing about with various filter possibilities. Myself, I would rather use filters designed by folks who have been at this professionally for years and years, guys like Charlie Hansen at Ayre whose team worked for more than a year designing their 16x minimum phase slow roll off filters, but of course, I have no problem with those who like to tinker otherwise.

When one gets to the point of one filter sounding good on one track and another filter sounding good on another track, it is safe to say one may have gone to far: does anyone have enough time to design a specific filter for every music track in their library, or even for every music genre? On taps, more taps means more processing power, and more processing power being used means more EMI, more EMI means more degradation of the entire system. There is a point at which adding more taps just degrades things, as the mathematical precision which one gains by using additional taps is well below the threshold of audibility.

In a DAC like the PS Audio DirectStream, where Ted has been refining the design for over seven years, it is safe to say he has developed some filters which he is satisfied with. He has also relaxed the demand on processing power (taps needed) by only oversampling integer values, which greatly reduces rounding errors. You could certainly oversample to 176.4 in Audirvana and see if you can make improvements for yourself...

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Being direct integer multiple or not doesn't have anything to do with rounding errors... (when done correctly)

 

Hmmm, Miska, is this simple enough to educate us on? The math seems much simpler, but I do not write these so I am sure you know what you are talking about...

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Hmmm, Miska, is this simple enough to educate us on? The math seems much simpler, but I do not write these so I am sure you know what you are talking about...

 

When you play with the maths a bit you realize that it's actually all the same as long as either of the rates is not irrational number. So in the end the only difference is in the thinking effort of putting it all together.

 

But what comes to irrational numbers is that you will end up with irrational sample values as part of processing and then you'll need to have a strategy how to deal with those. However, this is unrelated to the conversion ratios...

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  • 2 weeks later...
I'm using the ULN-8 with settings I found in a thread here.

 

I can't recall the poster, but it's one of those guys that's spent a lot of time tinkering. I recall one comment he made about thinking these settings were very DAC/system dependent, until he heard them on multiple systems and had positive feedback from others.

 

I had tried other settings people posted, as well as some tweaking of my own, but these have been the best for me.

 

Steepness: 7

Filter max length: 1,300,000

Cutoff freq.: 1.02

Anti-aliasing: 200.0

Pre-ringing: .86

 

I have it set to Maximum sample rate upsampling

 

Using version 1.5.10

 

If you try these, I'd appreciate your feedback.

 

Hi DreamOperator.. my apologies for the delay and thanks for your setup. I did try them today and they are very close to what I had ( everything is same except the Pre-ringing was set to 0.71 on mine vs .86) and they sound very transparent.. It looks like the small change in pre-ringing is making difference? The max sample rate on my was set to 176.8 (multiples of 2).

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Hi DreamOperator.. my apologies for the delay and thanks for your setup. I did try them today and they are very close to what I had ( everything is same except the Pre-ringing was set to 0.71 on mine vs .86) and they sound very transparent.. It looks like the small change in pre-ringing is making difference? The max sample rate on my was set to 176.8 (multiples of 2).
Hi vinoboy,

 

No worries at all. Glad you tried them and that you like them.

 

I couldn't tell you for sure what's making the difference, but if pre-ringing was the most different setting then likely it is that.

 

Also, I'm still unclear regarding which is considered better, max sample rate or multiple of 2. I simply have mine on max. Anybody care to chime in on that?

Hackintosh W7/OSX 3570k/16GB > Audirvana+ > Metric Halo ULN-8 > Rythmik F12 and Butler Audio TDB 2250 > Magnepan 1.7 > 13.5'x26'x7.5' room, HK/Limage setup

 

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