Chordette Gem - how to setup for 24/96K on Mac??

[happybob]

Hello folks. I've recently acquired a Chordette Gem as an interim DAC that I'm using with my late 2008 MacBook Pro (OSX 10.6). I'm struggling in three areas and would greatly appreciate any help...

 

1. How to setup the DAC via USB to playback 24 bit 96K files via iTunes? The Chordette is supposed to do 96K/24 bit via USB (but not via bluetooth). I go to the Audio Midi setup and for the USB DAC (that is the Chordette Gem) it only allows settings up to 48K 16 bit. No option for 96K 24 bit. But I do have this option for the built in output (internal speakers to the MacBook Pro). I'm doing all of this with iTunes turned off as I know things can't be changed when it's on. I've downloaded some 24 bit 96K WAV files just to verify in case that's a problem, but still nothing works. No options seem available to get the Gem into 96K/24 bit mode via USB even though it's supposed to support it.

 

2. Via bluetooth the Chordette Gem has lots of distortion with loud passages (AIFF, and WAV files). Is this normal? I need to drop the signal hugely (via either the iTunes or System) volume controls to reduce this somewhat. What gives? BTW, this reduction then muddies up the music.

 

3. Is there a way to control the Gem's volume level from the Mac's main volume control (as it does work for bluetooth) or can the level only be adjusted via the iTunes volume setting? Bummer if only the last since I can't then use my Apple remote to adjust volume.

 

Thanks much for your help!

 

-Bob

 

[The Computer Audiophile]

Hi Bob - Something tells me the Gem is not capable of inputting at 24/96 via USB. The specs below say the DAC is capable of 44KHz – 96KHz but that doesn't necessarily mean via any input (unfortunately). It may just mean the DAC chip itself is a 24/96 capable chip. Just a guess based on what you are seeing in Audio Midi Setup.

 

Not sure about the volume control as I use either a preamp volume or a volume control built into a DAC.

 

 

 

 

HARMONIC DISTORTION CHANNEL SEPARATION < -100 dB (1kHz, 24-Bit @ 44.1KHz Sample Frequency) 100dB @ 1KHz

DYNAMIC RANGE 112dB

SWITCHABLE DIGITAL INPUTS 1 x USB ( B type ) 1 x Bluetooth supporting A2DP Stereo Audio

ANALOGUE OUTPUTS 2 X RCA Phono

SAMPLE FREQUENCIES 44KHz – 96KHz

OUTPUT MAX OUTPUT IMPEDANCE 2V rms. unbalanced 75? (short circuit protected)

DIMENSIONS IN MM WEIGHT 160 x 70 x 40mm (Width x Height x Depth) 0.4Kg

 

[happybob]

Thanks for the perspective Chris. The Gem's specs are a bit ambiguous but I fear you're right about the limitations. I will try to get more info direct from Chord.

 

And BTW, a BIG thanks to you for all you've done to help folks launch into the realm of computer audio! I know I wouldn't have started my adventure into this realm if I hadn't found your website! I'm a longtime audiophile and knew I wanted to head in the direction of computer-based audio but didn't know how to progress sensibly.

 

The Gem is my "starter" DAC that I'm using just to play with things as I rip CDs and experiment with high-res downloads on my Mac. I'll be transitioning to something higher-end soon but am waiting for things to settle down just a bit in the marketplace. Along those lines, just the other day I had an exchange with the Sonic Studio (Amarra) folks and their comment was "Don't despair, we are looking into a 2 channel DAC for all you fans of our stuff." when I requested a 2 ch RCA I/O version of their models Three or Four...

 

I'd hoped I could adjust volume directly via the system volume control but I guess I'll have to wait till I upgrade to something like Amarra SW or maybe even something like one of the Wavelength DACs that allows for this control.

 

As an aside, the Gem has a "warm" sound which is what I need to tame my current system that is a bit lean and bright. Tonal balance is good on the Gem (for me), but as folks have indicated elsewhere it's not the last word on dynamics/transients/resolution and I'd agree. Nice little unit though that I'll likely keep just for portable bluetooth use - especially if I can figure out what's causing the distortion on the loud passages.

 

Thanks again,

 

-Bob

 

[fredg_31]

Hi Bob,

 

I'm a GEM user for 6 month now,

 

I ask myself the sames questions and mail it to Chord :

 

- how to setup 24/96 ? Not for the moment, Software is continuing to be developed for the higher bit rate support. We are hoping eventually this will be possible.

 

- how to setup volume in USB mode ? Impossible, volume is bypassed for quality reasons.

 

- how to improve PSU ? The power supply for the Gem is fine. We actually have several secondary power supply stages built into the Gem that improve the performance of the incoming 12V supply. This means that the external supply have virtually no effort on the sonic performance of the product.

 

- how to limit BTH distorsions ? by setting output volume to 50%, after burn in, distorsion desappeared in my case and now i can use 100% output volume.

 

As you sayed, GEM have a "warm" sound, and need a long burn in period (250 hrs min). The sound became better after burn in and after giving it good cables : acoustic zen wow for me.

 

Some persons Think GEM is as better as a REGA Saturn CD player. I think it is a good comparison.

 

regards,

sorry for my english...

Fred de Toulouse (France)

 

 

[happybob]

Thanks Fred for your info on the Gem. It would be nice to have full 24/96K support and also to have USB volume control but I can certainly understand why they don't do the latter - to optimize sound.

 

Your experience on the bluetooth distortion going away after a long break-in is encouraging to me. I'm at ~75 to 100hrs of break-in and I would say the distortion is less than it was when I got it, but it's still there. Here's hoping the distortion goes away entirely soon!

 

Thanks,

 

-Bob

 

[fredg_31]

Hi Bob,

 

Think about that : by setting BTH output volume of my Mac at 50%, distortions are really reduced, at 100% it was really really bad, now it's good after long long burn in : I am at > 1000 Hrs now.

 

Try also to move your GEM : distortions can result of interferences (microwave oven, DECT phone, electrical phase of your PSU, ...) ...

perhaps due to Mac OS : I'm using snow leopard and latest Iphone 3GS OS ...

perhaps due to music quality : I'm listening to Spotify Premium with Higher Bitrate or listening my bitperfect alac CD Collection (ripped with XLD) through ITunes.

 

Hoping they will disappear as for me, even if I do prefer GEM with USB, which produces better sound results (with a small USB Kimber Cable, not the silver : the standard's one).

 

Regards,

 

 

[happybob]

Hi Fred - I've tried various things to eliminate the distortion on bluetooth, but the folks at Chord actually gave me a good pointer that the problem may be in part due to the way Apple handles bluetooth specifically on the Mac (OSX 10.6.2 note this does not apply to iPhones which don't have this problem)

 

http://discussions.apple.com/thread.jspa?threadID=2171888&tstart=0

 

I've played around with some of the bluetooth parameters and indeed the sound is less distorted. Of course, I'm also breaking in the Gem as I do all of this so maybe the distortion is going away on it's own to some extent. I did try reducing the volume setting to ~50% and even lower and it did not noticeably reduce the bluetooth distortion, but it does of course eliminate a couple of bits of the digital signal resolution so the sound did change somewhat.

 

Moving forward, I'm transitioning to an integrated amp with a remote volume control so will likely just leave my Mac set to 100% and then adjust the volume via the integrated amp's remote. Also, I've got a USB extender on order so I'll have some experience soon in using the Gem via USB (currently, my Mac is too far away from the Gem to reach with one USB cable. Normally, I'd assume that this USB extender would trash the sound quality of the USB signal but based on info from Chord on how they batch the signal and then recreate it in the Gem, I'm not sure it'll matter. Will test with short and long cables though.

 

All of my source material is AIFF or WAV. Am just using iTunes for the rip, not using XLD at this point. Not sure how I'll do my full collection ripping yet, am hoping to just use iTunes and not need another program...

 

Here's hoping the bluetooth distortion goes away soon!

 

-Bob

 

[fredg_31]

HI Bob,

 

thanks for the link in your message, I ignored that we can play with A2DP protocol...

I've tried severals parameters and founded that my GEM supports 104 as maximum bitpool value, sound is really correct at 100% (for ALAC).

 

BTH protocol prefers set bitpool to 53 for 44.1 (320 kbs) or 50 for 48.

 

if you want to try :

 

defaults read "com.apple.Bluetoothaudioagent"

note your param values in case of...

 

then set Bitpool to a fix value by giving this value to 3 params.

defaults write com.apple.BluetoothAudioAgent "Apple Initial Bitpool (editable)" 104

defaults write com.apple.BluetoothAudioAgent "Apple Bitpool Max (editable)" 104

defaults write com.apple.BluetoothAudioAgent "Apple Bitpool Min (editable)" 104

 

disconnect and connect your GEM.

take a look at defaults read "com.apple.Bluetoothaudioagent" to confirm that bitpool negotiated is at 104, tell me if sound is better.

 

amitiés musicales,

 

 

[happybob]

Thanks Fred, I'll play some more with the bluetooth parameters and see if I can improve my bluetooth performance. Also, just got the USB extension cable - will see if that helps or not. Since it functions essentially as a 1 port hub, it may decrease the potential of the USB interface. Then again, it may work great! Ah, the fun of computer audio!

 

-Bob

 

[Mr.C]

You can use the system volume control with USB if you have Soundflower installed. It's free.

 

[happybob]

Soundflower sounds pretty cool, thanks for the tim Mr. C

 

I can't however find any info on whether or not Soundflower constrains the audio in any fashion (i.e. does it pass even 24bit, 96K audio and is there added latency or otherwise compromising of the sound?). Is there an easy way to disable/uninstall it if necessary?

 

Thx,

 

-Bob

 

[fredg_31]

Hi Bob,

 

does the burn in period finished ?

 

have you found sound improvements since last post ?

 

Regards,

Fred.

 

[happybob]

Hi Fred,

 

Yep, I think I've pretty much got the Chordette Gem all burned in... I've been using it via USB (not bluetooth) and it seems to sound pretty much the same now after x100 hours of use... Didn't change a huge amount in it's basic character but did get a bit more refined...

 

Great little DAC. I do wish though that it showed up on the Mac as a 24 bit, 96KHz device so that I could use it with software like Amarra...

 

Cheers,

 

-Bob

 

[ASB]

Bob, I have auditioned a Chordette with a 12V DC battery. (NP7 12V-7AH type)

 

It is much better than the power supply delivered by Chord. I would say have a try.

 

[happybob]

That's a good idea to try it with a good battery! Truth be told though, the Chordette Gem for me is an interim DAC that I'm using until I get my next DAC. I'm currently leaning towards something like the Antelope Audio Zodiac Gold, Weiss DAC 202, Metric Halo's possible new 2 channel product, etc.

 

The Gem has way exceeded my expectations of it, but I don't imagine it's up to the level of these other products; plus the Gem doesn't do 24bit and/or 192KHz high-res digital audio and it can't be used with Amarra, which I'm also leaning towards... Chord does have some highend DACs that do these things too...

 

Cheers,

 

-Bob

 

[fredg_31]

Hi Bob,

 

I consider too the GEM as an Interim DAC on my main system, Therefore I will keep it and use it for Headphone listening, having a DT990 vintage and a Naim Headline, its a good match for me for night sessions.

 

For the main system I'm thinking to abandon USB or Wireless DAC and give a try to old school BNC or RCA numeric interconnect.

 

I'm thinking at the moment to Naim DAC, Chord QBD76 or Devialet D-Premier (Amp with DAC integrated).

 

My Mac (with Amarra) will be interconnected to the DAC through a M2Tech Hiface USB Card and a good RCA interconnect.

 

You should try Amarra with the Chordette, It works fine for me (BT + USB) but I think it isn't as impresive as expected on my system...

 

Cheers,

Fred de Toulouse.

 

[happybob]

Hi Fred,

 

Interesting that the Chordette works with Amarra! I was told (by the folks at Amarra/Sonic) that in order to work with Amarra, the DAC had to show up as 24bits/96K on the Mac as an output device... Does yours show up as such, or maybe it doesn't matter?

 

Getting the bits to the DAC is indeed an ongoing saga it seems... I'm personally leaning towards the approach of asynchronous data transfer (USB or firewire) and then having a very good clock in the DAC that's independent from the source data clock. I sense though that SPDIF or AES/EBU approaches can be equally good - but probably are more finicky to get working optimally - due to the source and the DAC being tied together from a clock perspective.

 

I'm also excited to see that Amarra 2.0 was just released. It will be interesting to see what folks have to say about it.

 

Here's to both of our systems taking a big step forward as we transition to new DACs...

 

Cheers,

 

-Bob

 

[almaatakz]

There is also apt-x aspect to the Gem. check this thread for details. http://community.whathifi.com/forums/t/423443.aspx

 

I was very impressed with Gem's soudn via USB.

 

[happybob]

... unfortunately I've got one of the earlier gems that does not have apt-x capability... I could return to Chord to get updated, but with shipping, etc. I probably won't do that... USB works fine for me at this point.

 

-Bob

 

[JonP]

Hi,

 

I am thinking of getting the current model Gem (the ATPX one). I was wondering, however, what was the eventual story with the USB input? I need it to work with 24 bit, 48 khz files without requantisation or resampling. So it will have to drop off my shortlist if the current version cannot do this.

 

[fredg_31]

Hi JonP,

 

I have to say first that I find it is a pity in 2012 to plan to buy an USB dac unit wich is only capable to play 16/48.

 

Several dac cheaper than chordette will give you more : give a try to hegel hd2, musical fidelity v-dac2 or Hrt music streamer 2.

 

I have used a chordette during 3 or 4 years, i found it warm and analogic sounding, like a rega cd player : USB is 16/48 capable, bth is 32/48 capable (my unit wasn't apt-x capable)

 

Now i'm using an hegel hd20 with halide design bridge on coax1, another world for sure. I sold my chordette for 250 euros to a friend with a kimber kable cu.

 

Amitiés musicales,

Fred de Toulouse, France.

 

[JonP]

Hi Fred,

 

Actually your comments about the Gem sounding warm and analaogue sounding like a Rega CD player could not be a higher endorsement of a DAC - at least from my perspective. That is precisely what I want in a DAC.

 

Yes, unfortunately the Gem is 16/48 limited, however on the positive side, any oversampling is only done within the DAC chip and there is no prior resampling / upsampling of any kind as is the trend for the vast majority of USB DACs these days.

 

Infact the list of NUS USB DACs (non-upsampling DACs as opposed to NOS filterless DACs) that are budget priced is getting progressively thinner on the ground.

 

Personally I have never heard one of these upsampling DACs that I really like the sound of for very long, yet I have no trouble listening to even very cheap NUS DACs, such as the extremely cheap one integrated into my Musical Fidelity XCan V8P headphone amplifier for example (the latter to my ears sounds better than any seperate component USB DAC I have had in the house and all of those have performed upsampling before the DAC chip).

 

So for me, I would actually trade 24 bit upsampling asynchonous capability for 16 bit oversampling-only adaptive transfer any time - for me the latter sounds far more natural.

 

I realise what I say is very subjective and I am certain beyond a doubt that were I to move into the higher priced DACs, I would accept that the more advanced technology is capable of delivering better sound.

 

I am still very curious about the Gem and am attracted by the relative simplicity, the fact that it does not upsample, the build quality and the made-in-England factor (which really meant something when I was growing up).

 

There is also the ease with which I would be able to integrate it into a casual-listening bedroom system when I finally get a high quality DAC (for my loungeroom system), since I can use the bluetooth with my laptop computer and enjoy remote capability whilst lying in bed browsing the web and doing whatever else it is we do with laptops these days. A nice, cable-free way to relax without having to listen seriously or demand high sound quality.