[kitten]

I like Srajan's reviews - always very honest. I guess there wasn't enough time for the final piece or is there (even) more to come?

"And if I can get my two reference digital pieces fixed in time...I also want to create some additional context for the USB DAC performance versus expensive ($10,000 and $35,000 respectively) CDPs run thru their analog outputs."

[dspringham]

Interesting to note Srajan's comment on the Sig 30.2 Integrated with stepped attenuator vrs. 30.2 without.

"Had I endlessly labored and sweated, perhaps I might have talked myself into a tiny difference. But my sense of self isn't wrapped up in any wishful abilities to hear things that aren't there. Unless your hearing is simply a lot more astute than mine, I think you'll not hear a difference either. Which means that if you presently own the integrated and wish to add the Isabella (or any other) preamp, you're not compromising things one wit."

Is anyone here running the Isabella with the 30.2 Integrated and if so please comment (outside of the fact that the remote sensor on the integrated needs to be disabled). Since there doesn't seem to be any sonic compromises does anyone see any other downsides, upsides?

It seems that most Isabella users end up with the power amp version.

I'm planning a purchase of the Isabella w/Dac and already have a 30.2 integrated that is nicely broken-in with fresh, new batteries that I just installed. It's just that I kind of hate to give it up in exchange for the straight amp version. Anyone see any downsides to sticking with the integrated?

I'm sure Vinnie will weigh-in on this one with his own valued opinion.

Thanks in advance for comments.

Dave

[Vinnie R.]

Hi Dave,

Good post!

I'm sure Vinnie will weigh-in on this one with his own valued opinion.

Here is my take on the situation:

When customers who already own the 30.2 integrated order the Isabella, I offer to convert their 30.2 integrated to the power amp free of charge.  This way, there are not two remote volume controls to deal with (the Isabella uses the same remote control code as the 30.2, so it is a problem if you do not block the IR sensor of the 30.2 integrated, as they both want to go up and down when using the remote). 

I have carefully evaluated the integrated vs. power amp versions and found there is a sonic improvement going with the 30.2 power amp when using the Isabella.  While I will not say it is a substantial ("night and day") improvement, I found it to be better (maybe an extra 5%) with the power amp.  The sound was a little more dynamic and more open. 

Technically, these are the 2 differences:
 
1) The input impedance of the 30.2 power amp is higher, at 100k.  This is a better match with the Isabella (although the Isabella has no trouble driving the 30.2 integrated and still sounds great doing it , as Srajan pointed out)
 
2) Shorter signal path: The signal path from the RCA input jacks of the 30.2 power amp goes directly to the amplifier board (via the PIO caps), vs. with the 30.2 integrated, the signal goes to the front of the unit, volume control, and back to the rear of the unit where the PIO input caps and amplifier board are. 

In terms of appearance, I prefer the look of the 30.2 power amp with the Isabella better than the 30.2 integrated with the Isabella, but that's just me 

It seems that most Isabella users end up with the power amp version.

Our customers who buy a 30.2 and Isabella together go with the 30.2 power amp, which makes sense (less expensive; no need for two volume controls).  Almost all of our 30.2 integrated customers who purchase the Isabella send in their 30.2 to be converted to a power amp.

Hope this helps,

Vinnie

[Eadron]

Yes, my Omegas do sound better with the Isabella and 30.2 stereo amp than with the integrated. As Vinnie pointed out, not night and day, but better still  .

Jouni

[Thrasher]

From the sixmoons review:

About higher-rez files: "You can feed the Isabellina DAC a digital signal that was sampled higher than 44.1kHz. For example, even if the music was sampled at 96k or 192k, it will lock onto it and use that sampling frequency. It does not oversample, however, so if you send in 44.1k, you get 44.1k out (not some integer multiple of this sampling frequency). With regards to word lengths, if the files were 18, 20 or 24 bits, it will truncate to 16 bits. So it always plays back in 16 bits but the sampling frequency depends on the music file." In other words, upsampling transports like the Ensemble can interface with the Isabellina converter. My Zanden Model 5000s NOS converter would not, presumably because of its choice of receiver chip. "The receiver chip locks the incoming S/PDIF signal which, in today's case, converts it to I-squared-S and then feeds the digital-to-analog converter chip. The USB stream undergoes no S/PDIF conversion at all."

So, if I'm reading this correctly, if you download a 24/96 or 24/192 file, and feed it to the Isabella, it will "tuncate" to 16 bit but retain the 96 or 192 sampling rate, thereby outputting 16/96 or 19/192.  Is this correct?  What does that do to the sound?  Is roughly 1/3 of the information lost?

While ripping 16/44 CDs and playing back 16/44 makes intuitive sense, downloading 24 bit files and playing back 16 bit does not.  Please educate!

[Vinnie R.]

Hi Thrasher,

Welcome to audiocircle and the RWA forum!

What does that do to the sound?  Is roughly 1/3 of the information lost?

The music is not lost and only the least-significant bits are truncated, but the dynamic range of 16-bit depth is limited to 96dB (vs. ~ 120dB - 130dB for 24-bit).  So in theory, the dynamic range is lowered, but music recordings do not have anywhere near 96dB of dynamic range to begin with! 

And the bit depth does not limit frequency range - that is limited by the sampling rate. 

Even with the better specs on paper of 24-bit and upsampling/oversampling, I much perfer the sound of the 16-bit, NOS dac approach.
It's all a personal preference...

Best regards,

Vinnie

[Thrasher]

Just getting into this stuff.  I want to take advantage of the benefits of hi-rez content (24/96 or 24/192), as well as maximum audio quality from my CD collection.

Am I correct in understanding that the last 8 bits in a 24 bit word are largely unused?  The bits themselves reflect dynamic range only?  So in truncating (cutting off the last 8 bits of each word) no music is lost, just possibly, and very occasionally, the edges of an extreme dynamic passage?

Also, despite the truncating to 16 bit, the Isabella DAC maintains the sampling rate of the input (44, 96, 192)?  This would contribute to the analog sound as well, I would think.

I found this interesting insight on another forum:

The primary reason we use 24-bit in production is due to the fact that 24-bit words allow for greater resolution of low-amplitude audio. In production, it's not rare to track or otherwise record a source at very conservative levels where the majority of the audio may only be effectively represented with 12 to 16 bits per sample so as to prevent full-scale clipping of rogue transients. If we were to record at 16 bits per sample, such audio would be only effectively represented with 6 to 8 bits per sample. This is especially true with certain types of recording, such as recording Foley, where often times there may be only one or at least very few opportunities to record a given sound, thus recording at conservative levels is critically important.

When audio is compressed, limited or normalized, we must necessarily bring up the noise floor to obtain an increase in volume (a decrease in dynamic range), so longer word lengths are extremely advantageous in this regard. Since most types of audio, music especially, end up passing through several layers of compression and limiting, working at or above 24-bit is almost mandatory (in my opinion) to achieve the highest quality result.

As an engineer, I never expect any audible difference between 16-bit and 24-bit for a compressed master. For a final delivery, where no additional processing is expected to be applied, 16-bit should almost always suffice.

Thanks for your help--the Isabella seems perfect for me!

Thrasher

[Vinnie R.]

Hi Trasher,

So in truncating (cutting off the last 8 bits of each word) no music is lost, just possibly, and very occasionally, the edges of an extreme dynamic passage?

This is debatable, because the music doesn't have anywhere near the 96dB dynamic range to begin with, so what is really being lost?

Also, despite the truncating to 16 bit, the Isabella DAC maintains the sampling rate of the input (44, 96, 192)?  This would contribute to the analog sound as well, I would think.

I believe in maintaining the orginal sample rate - the less processing, the better (to my ears).

All this stuff has been debated many times on many various forums, but in the end, what really matters is what sounds good to you and how your equipment helps you connect to the music.  This cannot be measured and you cannot apply theory to it.  You have to listen and hear for yourself.

As I mention on the Isabellina web site, I believe that (when well-implemented), the 16-bit, NOS dac approach comes the closest to matching the finest sonic qualities of analog sources such as the richness of tone, extraordinary timing/pacing, and an effortless presentation of the music.  The Isabellina offers a natural and emotionally involving musical presentation that pulls the listener into the music and does not let go!

I've heard many dacs that on paper measure better (e.g. 24-bit, larger dynanic range, better SNR, etc.) but to me they fail in that they sound analytical, cold and sterile ("digital").  The Isabellina does not...

Best regards,

Vinnie

[Alwayswantmore]

I sold turntables in the day when direct drive was big. Direct drives had better specs than belt, so the majority of people assumed they must sound better than Thorens or Linn Sondec, etc. But look at most audiophile turntables today using belt.

I also put my Wadia 830 with factory P upgrade directly against the Isabella when making my decision to purchase. Isabella won (for all the sonic reasons Vinnie's states above). Sold the Wadia and bought a Macbook. My system has never sounded so real.

So specs may be hard to justify. But only your ears will tell you what's right.

[Frihed90]

Is that an AD1685 Dac chip?  Great choice, if so.  What about the clock?

[Vinnie R.]

Is that an AD1685 Dac chip?  Great choice, if so.  What about the clock?

Hi Frihed90,

We do not disclose information about the dac chip and clock that we are using.

All the information that is available can be found here:
http://www.redwineaudio.com/Isabellina.html

Best regards,

Vinnie

[TONEPUB]

Hi Dave,

Good post!

I'm sure Vinnie will weigh-in on this one with his own valued opinion.

Here is my take on the situation:

When customers who already own the 30.2 integrated order the Isabella, I offer to convert their 30.2 integrated to the power amp free of charge.  This way, there are not two remote volume controls to deal with (the Isabella uses the same remote control code as the 30.2, so it is a problem if you do not block the IR sensor of the 30.2 integrated, as they both want to go up and down when using the remote). 

I have carefully evaluated the integrated vs. power amp versions and found there is a sonic improvement going with the 30.2 power amp when using the Isabella.  While I will not say it is a substantial ("night and day") improvement, I found it to be better (maybe an extra 5%) with the power amp.  The sound was a little more dynamic and more open. 

Technically, these are the 2 differences:
 
1) The input impedance of the 30.2 power amp is higher, at 100k.  This is a better match with the Isabella (although the Isabella has no trouble driving the 30.2 integrated and still sounds great doing it , as Srajan pointed out)
 
2) Shorter signal path: The signal path from the RCA input jacks of the 30.2 power amp goes directly to the amplifier board (via the PIO caps), vs. with the 30.2 integrated, the signal goes to the front of the unit, volume control, and back to the rear of the unit where the PIO input caps and amplifier board are. 

In terms of appearance, I prefer the look of the 30.2 power amp with the Isabella better than the 30.2 integrated with the Isabella, but that's just me 

It seems that most Isabella users end up with the power amp version.

Our customers who buy a 30.2 and Isabella together go with the 30.2 power amp, which makes sense (less expensive; no need for two volume controls).  Almost all of our 30.2 integrated customers who purchase the Isabella send in their 30.2 to be converted to a power amp.

Hope this helps,

Vinnie

I agree with Vinnie.  I experienced the same thing when he converted mine to power amp only...

If he's doing it for free, you can't beat that for customer service!!!