[NewBuyer]

Hi Jim, Happy New Year!

I recently read the review of the HagUSB vs SB3 in the current issue of Positive Feedback Online where the HagUSB was compared to a modded SB3 (w/ modded linear PS). Each was feeding a Benchmark DAC1 by coax.

The reviewer noted several distinctions and differences regarding the final sound output, depending on whether the SB3 or HagUSB was used to feed the DAC1. The reviewer did appreciate the HagUSB but noted a clearly better sound result from the SB3-combo, in several major areas including dynamics, detail, attack/bite, bass, midrange, and treble (!)

As each was being used as a digital source only, and as the HagUSB uses a high-quality S/PDIF output transformer, I was surprised by this outcome (I had guessed at least equal performances in the comparison). 

Might the outcome have something to do with the quality of the clock in the reviewer's Mac-Mini used in the review? [I read your measurements about this in your November 29 2006 web-log, but I think this only relates to a lock/no-lock result?] A result of superior jitter-reduction from the modded-SB3 and linear PS (modded Elpac)? Or something else entirely?

Anyway, again this outcome surprised me, but I am certainly not the expert here - and would thus be very interested in your comments if you are please willing to share them. What are your thoughts please?

[hagtech]

Hey cool.  I didn't know about this review. 

As far as sonic differences, it's always amazing to me how bits are not bits.  So many things in the playback chain that can impact the sound.  Hard for me to guess why he liked the squeezebox better, I know very little about them.  A quick browse of their website and it appears that one uses a "slimserver" software package.  Does that work with iTunes or replace it?  I dunno.  I would think he used iTunes directly to the HAGUSB, no slimserver.  Does the software change things?  Maybe it resamples?  Were they both feeding 16/44.1k into the Benchmark? 

Is the squeezebox taking Ethernet input and not USB?  That would imply local buffering and reclocking of audio data.  The HAGUSB simply converts the USB packet on the fly.  There is no storage other than one previous sample  (being output while the new one is being received).  Timing is dependent upon the PC.  Is this apples and oranges?  Could just be we're looking at two very different methods of getting the bits off of a hard drive and into S/PDIF.  A more apt comparison would be a HAGUSB and an Offramp?

If I'm right about the Ethernet thing, then I would not be suprised it sounded better. 

jh

[Jon L]

It's not a fair fight really since the review compares a $600 modded package to $125 HagUSB. 

However, the biggest disadvantage of the HagUSB is the reliance on the USB bus power.  If Jim ever decides to sell the HagUSB with power jack to use a separate PS and/or battery, I think the world will be in for a BIG surprise 

[totoro]

Hey cool.  I didn't know about this review. 

As far as sonic differences, it's always amazing to me how bits are not bits.  So many things in the playback chain that can impact the sound.  Hard for me to guess why he liked the squeezebox better, I know very little about them.  A quick browse of their website and it appears that one uses a "slimserver" software package.  Does that work with iTunes or replace it?  I dunno.  I would think he used iTunes directly to the HAGUSB, no slimserver.  Does the software change things?  Maybe it resamples?  Were they both feeding 16/44.1k into the Benchmark? 

Is the squeezebox taking Ethernet input and not USB?  That would imply local buffering and reclocking of audio data.  The HAGUSB simply converts the USB packet on the fly.  There is no storage other than one previous sample  (being output while the new one is being received).  Timing is dependent upon the PC.  Is this apples and oranges?  Could just be we're looking at two very different methods of getting the bits off of a hard drive and into S/PDIF.  A more apt comparison would be a HAGUSB and an Offramp?

If I'm right about the Ethernet thing, then I would not be suprised it sounded better. 

jh

The sb3 does in fact get its feed via the network (not absolutely sure whether it's sent via tcp/ip or udp, but, I _think_ it is tcp/ip). So, yes, it does buffer the input before playing it (you get something like 1 minute worth of music playing if the sb3 loses its network connection for some reason).

The server just sends what is fed to it, with certain caveats (the sb3 only natively understands a few formats, so those it doesn't are converted-- for instance, apple lossless->flac). But, in any event, the server doesn't upsample.

[boead]

The reviewer said; “…I compared the stock and modified Squeezeboxes to two other methods of feeding my DAC to ensure I hadn't just fallen for the first gadget to catch my eye. First I ran the mini optical output from my Mac Mini to the Toslink input on the Benchmark. This setup was very lackluster at first and I was ready to give up after less than three songs, then I found you could output a 24/96kHz signal from the Mac by changing system settings. Moving from 16/44kHz to 24/96kHz was an enormous leap, and the 24/96kHz sound was very dynamic with good frequency extension and a decent soundstage….”

Is he saying that the Mac Mini upsamples 16/44 to 24/96 via its TOSLINK from his Apple Lossless files or even WAVs???


LOL, I love this quote; "... I don't know what a lot of this stuff does but it sure sounds good, and the new WBT connectors are fascinating to look at..." 

[boead]

more 
“…I first tried using the analog outputs of the Squeezebox directly into my preamp, and while acceptable for background music, it did not have much life. Dynamics were poor, frequency extremes were missing, and there was a veil over the music. I moved on to feeding the Squeezebox's digital output to the Benchmark and this setup showed serious promise….”

So the modified SB3 quickly became a what? Wireless transport from a computer? I though tthese things were decent DA converters? The reviewer dismiss it as a P.O.S. and goes onto the rest of the review using it with his Benchmark.
So really the article is comparing the SB3 (modified), the HagUSB and a Bel Canto PL-2 CD Transport.

So an unmodified SB3 ($300) sounds as good as his Bel Canto PL-2 ($5000) http://www.audionut.com/pk4/store.pl?view_product=281 and I have to assume he likes the Benchmark DAC1 (http://www.benchmarkmedia.com/dac1/) better then the Bel Canto PL-2 as a DA converter. Hummm. I know the Benchmark is said to be good but better then the Bel Canto?

:… Next up was the Hagerman Technology HagUSB, a simple USB converter that outputs an SPDI/F signal….”
And what the hell is the SB3? A complex machine?
“…HagUSB is simply a conduit to get the 0's & 1s out to your DAC. ….”
 

[NewBuyer]

...If I'm right about the Ethernet thing, then I would not be suprised it sounded better...

Hey Jim just curious: Given the details you've already stated about these processing differences, could you please elaborate on why you would expect Ethernet to be superior sounding?

...the biggest disadvantage of the HagUSB is the reliance on the USB bus power.  If Jim ever decides to sell the HagUSB with power jack to use a separate PS and/or battery, I think the world will be in for a BIG surprise 

Hi Jon L, is the USB bus power really that bad? (Genuine question there, I personally don't know). What would you expect from a separate PS or battery approach please, in the way of differences from the USB-powered approach?

[hagtech]

why you would expect Ethernet to be superior sounding?

Because the timing is separate from the data transmission.  With Ethernet, many samples are transmitted and stored into a fifo.  Maybe even thousands of them.  Data is then reclocked using a local oscillator, which has the potential for low jitter.

With USB, you don't buffer the data.  You get it and spit it out as S/PDIF right away.  Local oscillator is a PLL that locks to the timing of the transmissions.  Data and timing are still connected.  [ok, just to make sure I don't oversimplify: the packets come in at 1kHz, so there is indeed storage of either 44 or 45 'samples']

My original application of the PCM2704 circuit was in the CHIME, which has reclocking.  Together they form a system that eliminated the timing issues.  The HAGUSB was a low-cost spinoff from the CHIME and lacks the enhanced performance (but hey, it's as good as all the other 2704 or 2706 devices out there).

jh

[poseidonsvoice]

Jim,

Interesting discussion. I understand that because of the reclocking (PLL) designed into the Chime that the timing issues of SPDIF are taken care of, i.e. jitter is dropped way low. I was wondering if the HagDac can accept I2S input directly and if you had considered a version of your HagUSB that outputed I2S directly? At the same time one may consider this unnecessary given that the HagDac has a reclocker on board.

See Doede Douma's interpretation here: http://www.dddac.de/pics/dddac1543mk2/usb-circuit-k.gif

[hagtech]

HagDac can accept I2S

No, it doesn't.  This is one of those design decisions you make, which you then live with.  It was a fork in the road.  I decided that nobody had a DAC with I2S inputs.  Ok, maybe a few Diyers.  Compare that to the universal standard.  It was all about compatibility.

The other reason was one of isolation.  I was adamant about zero galvanic connection between the PC and the audio system.  No ground garbage.  That's why I put in such a good S/PDIF tranny.  It couples a beautiful signal and isolates at the same time.  Not as easy with I2S.  Plus, the original USB circuit was dedicated within the CHIME, and so I wanted switching between sources.  Without adding too much complexity, the simple and straightforward solution was to switch S/PDIF inputs.  It also gave me the extra green light from the receiver.

So, if you wanted a HAGUSB with I2S outputs, what should they look like electrically?  Should they be RS-485?  LVDS?  PECL?  CML?  75-ohm levels similar to S/PDIF?  LVTTL?  What cable impedance?  I don't believe much of a standard has developed.  Sure, I could bite the bullet and build one with LVDS, but just how many DACs would it plug into? 

jh

[poseidonsvoice]

Jim,

Excellent points. I've asked a few other manufacturers and they echo your comments. There are about a half a dozen dacs out there with I2S input capability. Many of them are very highly priced (Zanden, Northstar, Audiologic, Perpetual Tech, etc...). A few have been modified to accept an I2S input like Steve Nugent's (Empirical Audio) take on the Benchmark DAC.

Very interesting the choices one has to make to sustain a business.

Anand.

[WGH]

My original application of the PCM2704 circuit was in the CHIME, which has reclocking.  Together they form a system that eliminated the timing issues.  The HAGUSB was a low-cost spinoff from the CHIME and lacks the enhanced performance

I have been a very happy owner of a HagUSB until I read the Positive Feedback article. OK, I'm still a happy owner but was wondering if the jury is still out on the benefits of adding the HagClock as explained on pg 11. In theory it seems like one small (and affordable) step towards the enhanced performance of the Chime.
http://www.audiocircle.com/index.php?topic=25147.0

[hagtech]

adding the HagClock

Making a better 12MHz clock for the HAGUSB will not fix anything (or at least not be very effective).  The ugly little secret nobody wants to talk about is that the output audio clock is derived from the clock in the PC, not the one in the HAGUSB.  You need to put the HAGCLOCK inside the PC, where the USB audio timing is referenced. 

jh

[NewBuyer]

adding the HagClock

Making a better 12MHz clock for the HAGUSB will not fix anything (or at least not be very effective).  The ugly little secret nobody wants to talk about is that the output audio clock is derived from the clock in the PC, not the one in the HAGUSB.  You need to put the HAGCLOCK inside the PC, where the USB audio timing is referenced. 

jh

This is extremely interesting information. I'm guessing that different PC motherboards will have different quality clocks then, which will affect the audible result with any USB DAC or an S/PDIF converter like the HagUSB.

Jim, here's a naive question for you please: Would this situation be improved with a product that simply converted S/PDIF from Ethernet instead of USB, say, a "HagNET" type product?

Several people have expressed interest in a network (ethernet) converter of this type that would contain no DAC (including inquiries to SlimDevices regarding if they might ever produce a digital-only Squeezebox).

However, perhaps this clock timing issue would exist with the ethernet medium too, just like with USB. What do you think please?

[hagtech]

different PC motherboards

Indeed.  Had a customer who could not lock to his Altmann via HAGUSB.  Turned out to be the PC clock was out of spec for redbook.  This probably happens occasionally, as the USB clock spec is 500ppm yet redbook is 100ppm.  So a PC oscillator slightly out of tune generates a HAGUSB output that is either too fast or too slow for some DACs.  That would be HAGDAC included.

I did some tests, looking to see how a HAGUSB maintained output frequency, thinking maybe it adjusted itself slightly up/down to keep it's FIFO full.  Thought I might see something on a 7-digit meter.  But it was solid.  Ok, thermal drift as things warmed up, but that's it.  Anyway, the output frequency was different for ever PC or mac I hooked it up to.  This jives with the PCM2704 spec and that 6moons story from a few years back by one of the Japanese TI development team.  Its really hard to figure out exactly what is going inside that chip.  Just not enough of it published.  There is potentially some tie-in for the audio recovery PLL based on the local clock too.  So the end result is possibly dependent on both clocks.  Multiple feedback loops going on.  Local clock does USB reception, so maybe there is some synchronization between the two prior to PLL.  Personally, I think that would be a very bad thing to do. 

product that simply converted S/PDIF from Ethernet

Yes, I think this would be a better situation.  More cost and complexity, but output timing would be solely dependent on local clock, which you could make real good.

jh

[AliG]

I have been a very happy owner of a HagUSB until I read the Positive Feedback article

Alas! There is something you need to learn, if you want to be happy in this hobby - NEVER let people's opinion influence your happiness. Many people, when they bought a piece of gears, they quickly come to the forum to tell people about it, hoping that people will tell him that he has made the right choice. Wrong mentality! You should always let your own ears deciding how happy you are.  There're always some people out there who do not care for the sound of your gears, so what?! They don't have the same ears as yours. Audio is like making coffee, some people like 1 teaspoon of suger, some like 2 teaspoon, some prefers no sugar at all.

So, forget about all these reviews, if you're happy with what you have - screw them!

[WGH]

Alas! There is something you need to learn, if you want to be happy in this hobby - NEVER let people's opinion influence your happiness.

I have been a very happy owner of a HagUSB until I read the Positive Feedback article.

Actually that comment was very tongue in cheek. I started in this hobby building Heathkits and Dynaco gear and even though that equipment is long gone I don't upgrade very often. I know the value in classic equipment, my shop speakers, which are heavily modded JBL L88's with the original speakers, have tighter cleaner bass than the Von Schweikert VR2's, even if they don't go down as low. I did finally put a new Goldring G1042 on the Harmon Kardon T55C turntable I bought in 1985, a very nice sounding deck. I am going to miss the auto arm lift when it dies.

I have read so many reviews about the "lifting of veils" and "removal of scrims" since the 80's that I would think the performers should be sitting in your lap by now, but sadly it isn't so. I am hardly swayed by the overly flowery writings of enthusiastic reviewers.

I have two USB to S/PDIF converters. The second one is a M-Audio Transit. Comparing the Transit to the HagUSB is like the difference between a toy piano and a baby grand, with the HagUSB by far the best sounding. I now use the Transit to pass through AC3 to a surround processor.

Thanks Jim for clearly explaining the timing problems with USB. If you ever decide to try an ethernet solution I will be first in line.

[Braden]

I don't mean to change the topic at all, but does anyone know of a product that would convert to 44.1k s/pdif maybe via usb? I'm basically just trying to fully use the hagdac when hooked up to my computer as I regularely use it to watch movies that don't have 44.1k audio.

[WGH]

use it to watch movies that don't have 44.1k audio.

What movies don't have 44.1k audio?
I can use the HagUSB just fine with either Media Player Classic or ZoomPlayer and ffdshow Audio Decoder. If you are using ASIO4All make sure you are not resampling to 48KHz. Set the output in either player to DirectSound: USB Audio DAC. I removed ReClock in order for Media Player Classic sound to work with the HagUSB.

[Lord Chaos]

My experiences with the Squeezebox... I started copying music to my computer a year and a half ago, mainly so I could play the music over Teamspeak for friends. Then I discovered how handy playlists are, and how convenient it was to have the music in one place, so I copied just about my whole CD collection to WMA lossless.

Eventually I wanted the same versatility in my bedroom, so I bought an Archos AV500 portable, assuming that with the big hard drive their "WMA" spec included "WMA Lossless." Nope. For a time I started ripping CDs twice--WMA lossless and WAV--but that got tedious. Then I learned about network media players.

The Squeezebox arrived and was quite simple to set up. At about the same time the earpads on my old headphones fell apart so I had to replace them. I ended up with Shure E500s, which are very good. The Archos player has a good headphone amp. As soon as I plugged these 'phones into the Squeezebox, though, I found the limits of their headphone amp. It's very noisy, and lacks guts. Bass is pretty thin, and I'm not the kind who wants his head turned inside out. I want the bass to be there, along with everything else.

So, the Squeezebox with Slimserver does a good job of getting the music where I want it physically. I just bought a Benchmark DAC-1 to solve the headphone problem. I haven't hooked this up yet. The Shure headphones are remarkable. All of the music is there, but not strident. I can easily get lost in the music.

Now, of course, I want to use the same headphones with the computer that does daily duty for writing and other activities. It also has a noisy headphone circuit, so I'm looking for a USB-to-SPDIF converter to use with the DAC-1... which is how I ended up here. This forum is quite a resource.

If I had it to do over again ... I think I'd have just stayed with a bedside CD player.