[SlimDevices: Audiophiles] New AKM 4490 DAC

[Squeezemenicely]

The Schiit Bifrost now uses the new AKM 4490 chip, current users can
even upgrade their DAC with a new board.

That is what I did - and I love it. To me it sounds even better than the
device was before. CAREFUL - no blind testing, not scientific - just an
impression (please ignore, if you cannot live with this)

Obviously the difference is not night and day - but the soundstage seems
wider and more 3 dimensional. Also like a veil has been lifted, the
highs are very clear and bass is very precise and powerful. The old
Bifrost was more diffuse - but also very good.


I think it is great that these devices are upgradeable. There is even a
more expensive Multibit option, which is supposed to sound great. But I
am staying in the Delta Sigma DAC camp for now. If you are looking for a
DAC to make your Squeeze sound better, try out the Bifrost.



LMS 7.9.0 on Pi2 (Max2play)
Synology DS-414 NAS
Squeezebox Touch, Squeezebox Boom, Squeezebox Radio, HifiBerry
PicorePlayer
Schiit - BIFROST AKM 4490 Dac
Spotify Premium
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[Fizbin]

Anyone else using this DAC with their Squeezebox product, or more
specifically...a Touch? Does it bring it closer to the sound of the
Transporter?


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[MichaelJ]

Post by Fizbin
Anyone else using this DAC with their Squeezebox product, or more
specifically...a Touch? Does it bring it closer to the sound of the
Transporter?

I had been using the über version of that DAC. After setting up a
passive pre amp and A/B comparing it with the analog op of the Touch, I
sold the Bifrost. This was a subjective evaluation only....my ears, my
equipment, my room. YMMV.


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[darrenyeats]

The analogue output of the Touch measures well, I like the harmonic
distortion profile (reducing distortion into higher orders, regarded as
"musical"). The main weakness is a weak output impedence of 800 ohms
meaning it should be used with an active preamp or integrated (not
direct to power amps or actives). Check out Stereophile for JA's
measurements.
Darren



Check it, add to it! http://www.dr.loudness-war.info/

SB Touch
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[cliveb]

Post by darrenyeats
The analogue output of the Touch measures well, I like the harmonic
distortion profile (reducing distortion into higher orders, regarded as
"musical"). The main weakness is a weak output impedence of 800 ohms
meaning it should be used with an active preamp or integrated (not
direct to power amps or actives).

In what way is an 800 Ohm output impedence "weak"?
Line level outputs on sources typically have an impedence of about 1k
Ohm, so the Touch's 800 sounds entirely normal to me.



Transporter -> ATC SCM100A
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[darrenyeats]

Post by cliveb
In what way is an 800 Ohm output impedence "weak"?
Line level outputs on sources typically have an impedence of about 1k
Ohm, so the Touch's 800 sounds entirely normal to me.

Well the Transporter is much more like it (100 or ohms via RCA). My DAC1
is 60 ohms via XLR. When I connected my Touch directly to my SCM50s I
found it a bit "stunted" at the frequency extremes, compared to the
DAC1, though otherwise really rather good. I attributed this to the
output impedance since the Touch is generally blameless otherwise,
including frequency response of course.

FWIW I found out about the output impedance being 800 ohms quite some
time later.
Darren



Check it, add to it! http://www.dr.loudness-war.info/

SB Touch
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[Julf]

When I connected my Touch directly to my SCM50s I found it a bit
"stunted" at the frequency extremes

How did you determine that? Usually a high output impedance causes a
slight drop in high *or* low frequencies depending on the configuration
of the amp it is driving, but not both at the same time.



"To try to judge the real from the false will always be hard. In this
fast-growing art of 'high fidelity' the quackery will bear a solid gilt
edge that will fool many people" - Paul W Klipsch, 1953
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[Mnyb]

It really depends on what it drives , most active amps and preamps have
input impedance of 10kohm or more in some cases much more . So it's not
per Defenition a problem driving a power amp directly . With the wrong
power amp or preamp you can have an issue .

If I remember rigth some old professional standards have 600ohm as
recommended input impedance such a component would be a problem for the
touch to drive , especially if its output impedance varies with
frequency ( or the driven amp,or preamp has similar issues varying input
impedance .

So just take care when pairing the Touch almost every normal component
is ok . But some old pro stuff may not be ok or some of the more
esoteric audiophool equipment , where they left sensible design practice
in the dust can be issues .

I have tried some of my squeezeboxes with a semi passive gamut preamp a
decade ago, and it sounded polite , just as suggested :) but that's not
what I consider good equipment today ..

Their are two ideas here .

Source very low impedance preferably 0 ohm no variation in the audible
range 20-20k amp high impedance 20kohm or more also linear within 20-20k
.

Impedance matching source and sink should have the same impedance ( say
600ohm ) and also the reactive parts should match and be close to 0 so
both source and sink should be close to resistive with the same
impedance , a more old school aproach .

As an off topic side note in industrial electronics ( where I work ) we
have ditch both these ideas in the 60-70's going for current source
transmission of analog signals ( in the rare case of using an analog
signal at all ) 0-20mA or 4-20mA this is much more resilient to long
cable lengths etc than trying to send a voltage the sender is a current
source ( near infinite impedance ) and the recieving end is like 100 or
500 ohm ( preferably 100ohm high impedance inputs are prone to noise
pickup , low impedance inputs basically " shorts " incoming noise ) the
nice thing is that impedance can be whatever within a certain range
current is current in a series circuit , this topology is linear until
the source can't drive the circuit anymore usually due to the power
supply which is usually 24 volts if that can't make 20mA there is a
problem , but all is fine until you hit the limit .

I think Krell used this idea for a while with some proprietary interface
between amp and preamp , naturally touted as a revolutionary idea :) (
besides the fact that any nearby industry had this for decades .... )



--------------------------------------------------------------------
Main hifi: Touch + CIA PS +MeridianG68J MeridianHD621 MeridianG98DH 2 x
MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3
sub.
Bedroom/Office: Boom
Kitchen: Touch + powered Fostex PM0.4
Misc use: Radio (with battery)
iPad1 with iPengHD & SqueezePad
(spares Touch, SB3, reciever ,controller )
server HP proliant micro server N36L with ClearOS Linux

http://people.xiph.org/~xiphmont/demo/neil-young.html
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[Julf]

( besides the fact that any nearby industry had this for decades .... )

The high-end audio is very good at ignoring 100 years of scientific
research, knowledge and progress.. :)



"To try to judge the real from the false will always be hard. In this
fast-growing art of 'high fidelity' the quackery will bear a solid gilt
edge that will fool many people" - Paul W Klipsch, 1953
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[arnyk]

Post by Julf
How did you determine that? Usually a high output impedance causes a
slight drop in high *or* low frequencies depending on the configuration
of the amp it is driving, but not both at the same time.

Please don't ignore the 500 pound gorilla in this room - it was no doubt
a casual sighted evaluation.


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[cliveb]

Well the Transporter is much more like it (100 ohms via RCA). My DAC1 is
60 ohms via XLR. When I connected my Touch directly to my SCM50s I found
it a bit "stunted" at the frequency extremes, compared to the DAC1,
though otherwise really rather good. I attributed this to the output
impedance since the Touch is generally blameless otherwise, including
frequency response of course.

Did you connect the DAC1 to your SCM50s using its XLR output? If you
did, then I would say the reason that the Touch sounded "stunted" in
comparison is far more likely to be because of its unbalanced output
than its output impedence. (And of course if you didn't level-match then
the comparison means nothing).

While it is true that balanced doesn't really offer any noise immunity
advantages over the short runs we use in a domestic setup, I strongly
believe that the galvanic isolation it provides is worthwhile. I've
always found that genuine balanced connection sounds somehow more
"focussed" and "organic". A dyed-in-the-wool audiophile would probably
say that the "blacks are blacker".



Transporter -> ATC SCM100A
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[Julf]

Post by cliveb
While it is true that balanced doesn't really offer any noise immunity
advantages over the short runs we use in a domestic setup, I strongly
believe that the galvanic isolation it provides is worthwhile.

Balanced doesn't necessarily provide any galvanic isolation, unless it
is implemented using transformers. A balanced, differential input does
provide a way to separate the signal from safety earth / power supply
ground, thus avoiding ground loops.



"To try to judge the real from the false will always be hard. In this
fast-growing art of 'high fidelity' the quackery will bear a solid gilt
edge that will fool many people" - Paul W Klipsch, 1953
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[cliveb]

Post by Julf
Balanced doesn't necessarily provide any galvanic isolation, unless it
is implemented using transformers. A balanced, differential input does
provide a way to separate the signal from safety earth / power supply
ground, thus avoiding ground loops.

Perhaps my use of the term "galvanic isolation" was not correct.
I was referring to the fact that a proper balanced connection breaks the
link between the ground planes.
Does true galvanic isolation also require a break in the signal
connections? If so, I have learned something.



Transporter -> ATC SCM100A
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[Julf]

Post by cliveb
Does true galvanic isolation also require a break in the signal
connections? If so, I have learned something.

True galvanic isolation is just that - true isolation, where there is no
direct electric (galvanic) connection between the two devices. Done
using isolation transformers or optoelectrics - either an optocoupler or
a fibre connection.

The best example is ethernet using twisted pair (cat5, cat6 or whatever)
network cabling, where the ethernet interface contains tiny transformers
("magnetics") for the signal pairs.



"To try to judge the real from the false will always be hard. In this
fast-growing art of 'high fidelity' the quackery will bear a solid gilt
edge that will fool many people" - Paul W Klipsch, 1953
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[arnyk]

Post by Julf
How did you determine that? Usually a high output impedance causes a
slight drop in high *or* low frequencies depending on the configuration
of the amp it is driving, but not both at the same time.
True galvanic isolation is just that - true isolation, where there is no
direct electric (galvanic) connection between the two devices. Done
using isolation transformers or optoelectrics - either an optocoupler or
a fibre connection.
The best example is ethernet using twisted pair (cat5, cat6 or whatever)
network cabling, where the ethernet interface contains tiny transformers
("magnetics") for the signal pairs.

Good examples, but some cases where the connection is balanced but there
is galvanic might bear mentioning:

USB 2.0 - two exceptions

(1) USB Power. A galvanically isolated USB device should supply its own
power

(2) Very high speed USB 2.0 (hard drives, etc) where the usual
transformer appears to be dispensed with for the sake of speed.

Also:

HDMI is not galvanically isolated, same basic reason as (2).


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[Julf]

some cases where the connection is balanced but there is a galvanic
connection might bear mentioning

Indeed. Balanced does not automatically imply galvanically isolated.



"To try to judge the real from the false will always be hard. In this
fast-growing art of 'high fidelity' the quackery will bear a solid gilt
edge that will fool many people" - Paul W Klipsch, 1953
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[StephenPG]

Very important to level match, I know from experience owning a Touch and
two Duets, the Duet outputs 1.8v and the Touch 2.0v. Enough to seriously
skew any casual listening test.

Also, darrenyeats, my Touch sounds just fine into a Quad 306!


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[pablolie]

i have a Benchmark DAC2HGC. for convenience and consolidation of
sources. honestly i can't tell the DAC2 from the built-in Touch DAC if i
connect the latter direct. it is a pretty good one. the reason for the
external DAC is merely flexibility and consolidation. i basically think
competently DACs sound pretty darn indistinguishable (except for
built-in $1 stuff), but when you build a system there are other
considerations at work for me.



...pablo
Server: Virtual Machine (on VMware Player) running Ubuntu 12.04 + LMS
7.7.5
System: SB Touch --optical->- Benchmark DAC2HGC --AnalysisPlus Oval
Copper XLR->- NAD M22 Power Amp --AnalysisPlus Black Mesh Oval->- Totem
Element Fire
Other Rooms: 2x SB Boom; 1x SB Radio; 1x SB Classic-> NAD D7050 -> Totem
DreamCatcher
Computer audio: workstation --USB->- audioengine D1 -> Grado
PS500e/Shure 1540
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[darrenyeats]

Post by StephenPG
Very important to level match

Agreed.

Post by StephenPG
Also, darrenyeats, my Touch sounds just fine into a Quad 306!

Several points:
- My comments are based on a 10k ohms input impedance, which for a Touch
is barely 1 to 10 impedance relationship.
- The input impedance of a 306 is 20k ohms, a much better situation.
- The output impedance of an SB3 isn't that hight either (dipping to 550
ohms) ... did you compare A/B level matched to a DAC with low output
impedance ... something like Schiit Bifrost at 75 ohms? If not, then
arnyk's gorilla in the room has got an even bigger brother.

Post by StephenPG
i have a Benchmark DAC2HGC. for convenience and consolidation of
sources. honestly i can't tell the DAC2 from the built-in Touch DAC if i
connect the latter direct. it is a pretty good one. the reason for the
external DAC is merely flexibility and consolidation. i basically think
competently DACs sound pretty darn indistinguishable (except for
built-in $1 stuff), but when you build a system there are other
considerations at work for me.

Well you have compared A/B (and let's assume level matched).

The input impedance via XLR for a NAD M22 is 200k ohms! That's unusually
high for a power amp, so your comparison speaks little to the general
case.
Darren



Check it, add to it! http://www.dr.loudness-war.info/

SB Touch
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[arnyk]

Post by darrenyeats
Well you have compared A/B (and let's assume level matched).
The input impedance via XLR for a NAD M22 is 200k ohms! That's very
unusually high for a power amp, so your comparison speaks little to the
general case.
(BTW, impedance aside, I think you're spoilt a bit by the Touch - it's a
well sorted DAC - not every cheap DAC is!)

Two words: sighted evaluation.


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[arnyk]

Post by cliveb
In what way is an 800 Ohm output impedence "weak"?
Line level outputs on sources typically have an impedence of about 1k
Ohm, so the Touch's 800 sounds entirely normal to me.

Modern line level outputs frequently have source impedances on the order
of 50-75 ohms. 1000 ohms or thereabouts seems to me to be very old
school.


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[Squeezemenicely]

Post by MichaelJ
I had been using the über version of that DAC. After setting up a
passive pre amp and A/B comparing it with the analog op of the Touch, I
sold the Bifrost. This was a subjective evaluation only....my ears, my
equipment, my room. YMMV.

In the other thread you stated your age, this has also something to do
with it. I am just shopping for varifocals - so I am also getting used
to the idea that some things do not get better as age progresses. ;-)
This is not ageism, just a fact.



LMS 7.9.0 on Pi2 (Max2play)
Synology DS-414 NAS
Squeezebox Touch, Squeezebox Boom, Squeezebox Radio, HifiBerry
PicorePlayer
Schiit - BIFROST AKM 4490 Dac
Spotify Premium
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[Greg Erskine]

Post by Squeezemenicely
In the other thread you stated your age, this has also something to do
with it. I am just shopping for varifocals - so I am also getting used
to the idea that some things do not get better as age progresses. ;-)
This is not ageism, just a fact.

Can you state what is the age group of people can respond to your
posts?

Post by Squeezemenicely
12 < 29

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[Squeezemenicely]

Can you state what is the age group of people can respond to your posts?

Oh come on. You probably know exactly what I mean. Obviously our hearing
changes with age and is different with 70.

But also if trying to hear the difference in audio equipment, it is best
if you have not been partying at a Technoclub all weekend and made your
ears bleed.

Just reminds me of when I thought, there is no big difference in SD TV
and HD, until I got glasses and was pretty amazed - I thought my sight
was pretty perfect before.



LMS 7.9.0 on Pi2 (Max2play)
Synology DS-414 NAS
Squeezebox Touch, Squeezebox Boom, Squeezebox Radio, HifiBerry
PicorePlayer
Schiit - BIFROST AKM 4490 Dac
Spotify Premium
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[MichaelJ]

Post by Squeezemenicely
In the other thread you stated your age, this has also something to do
with it. I am just shopping for varifocals - so I am also getting used
to the idea that some things do not get better as age progresses. ;-)
This is not ageism, just a fact.

I totally agree. That's why I said YMMV. While I can still hear up to
13kHz, there is a roll off above 8kHz.
Think of the $$ I'm saving on not needing super tweeters!:)


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