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Apogee Duet tweak

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Hello evryone,

New member here. Great site!


Lastly I ended up with an audio setup the quite impresses me. Just switched my Moon i5080 for a Quad 303. I know it’s an old peice of gear but Jean Desrochers (owner of Planabox) upgrades them with up to date and better suited parts, and with a few simple tweaks the old fart REALLY shines with my Proac tablette 2000 (see thread on those if you own them). It shines so much that the rest of the setup began to show it’s flaws.


The Duet is the end of the road for me as I needed a very good mic pre and I’m not willing to spend thousands on equipment anymore. But the Quad allowed the Duet to show a little edgy temper. I’ve been DIYin’ for a couple of years and learned a lot, mostly from the Monica DAC from DIY Paradise and from many other diy sites and forums. So now is my turn to get involved at sharing the knowledge that keeps this hobby exciting, beside spending money end agonising after sleepless nights.


So here´s the tweak, if you got the guts. This is probably voiding the warranty, so be aware.

You’ve got 4 screws at the bottom to get access to components. Gently pull out the top (I didn’t need any tools to seperate top from bottom) You need about 3 sq.in. of ERS paper. This is EMI and RFI isolation laminate made from what seems to be ferrite streaks and polyester whool, available at Parts Connexion. Touch a grounded appliance before touching anything inside the DUET: this baby is static sesitive without it’s shell. Spot every opamp on top and bottom of the circuit board. I don’t remember how much there is but there is at least 15-20 of them. Using tiny pieces of ERS paper custom cut to fit on top of the opamps, stick them in place using toothpicks or better anti-static tools. NO METAL TOOLS.


Avoid covering caps, diodes and complex ICs (the big ones with legs all aroud). everything in there is surface mount so make shure you know how to differciate bits and pieces. Usually 8 prong ICs are the ones in there. They vary in size. Put back daddy in mommy and you’re done (snug fit in there so be careful as suface mounts plugs are fragile when not in position).


The result is a difference in the range of listening to redbook vs. 24/176.4 recordings. Added to that the fact that sibilliance is dead gone. The sound gained weight, the strereophonic image has grown in every dimension and pulled back a little. I now feel the vertigo of true émotions. When critics and reviewers talked about magic, I couldn’t really understand the meaning of it, until I came up with this tweak. I spent three days sitting on a stool, curtains closed for better room treatment, forgetting to eat and procrastinating everything else. The presentation is no more digital. It’s v’been a couple of weeks and it is still freaking me out.


I use Itunes with built-in audio set at 16/44.1 and Duet at 24/88.2

I’ve tried upsampling in Audacity with shaped dither at 24/96 and 24/88.2, but it lacks magic.


As for the Quad, Jean told me it would come to it’s best in about 6 months of use. Futile it is to say that I can’t wait!


Let me know if you try it, anyway, that ERS paper has always served me well on simple DACs and opamps.


Hear you later




Update: Added pictures for the voyeur en vous.

refs for ERS paper:




Please be reassured that this is no publicity. I have no interest in those parties but as a happy customer :o)


Message from Parts Connexion

IMPORTANT NOTE: Stillpoints, the distributor for ERS in the audio market, has just informed pcX that

this may be the very last production lot of ERS available. The recent severe economic downturn has

effected the factory which makes this material....most, if not all, ERS offerings will cease production.

As a result, pricing from Stillpoints is going up (effective immediately - Jan 21st, 2009).....see below.


Digital music addict[br]Mac G5 quad -> Apogee Duet -> Quad 303 (Planabox) -> Proac tablette 2000 -> Sweeeet bliss

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The most tricky part is to first get the firewire plug out. The pictures marked with X are where I had put some ERS but then noticed some faint digital errors. The complex ICs don’t generally like that treatment. Had to take it off… But the Duet has been working flawlessly for the last 3 weeks, and since I’m working from my home office, it only gets some rest when I do.


As Stillpoints is going out of business, I remember reading somewhere on the Altmann BYOB DAC a similar product called the Tubolator, no longer distributed. It was some kind of ferrite goo you had to brush on the IC (scary!).




Digital music addict[br]Mac G5 quad -> Apogee Duet -> Quad 303 (Planabox) -> Proac tablette 2000 -> Sweeeet bliss

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  • 2 weeks later...
  • 1 month later...

Hey there,


(It’s v’been a while since I looked around on the forum)


I brought my satisfaction a little further with some software config.


Instead of using the wheel as volume control, I managed bypass a stage somehow:


In the Maestro Mixer window, select the Out L-R option for the "TO HARDWARE" slider. This slider is going to be your volume adjustment tool. So TURN IT DOWN NOW, otherwise your amplifier will be fed with full preamp output.


Then go to Maestro Control window and slect the "INSTRUMENT AMPLIFIER" option in the output section.


Then back to the mixer and gently slide up that volume gain slider.


Voilà! More dynamics, more musical, greater space, it sound’s more natural and with even more details.

Impressive difference! Can’t explain why. Seems like this bypasses a stage (resistor attenuation? software attenuation?) but it sounds like the sound is less filtered and more attrrrractive!


Another fact I’ve read somewhere and tried: In the audio midi setup, set the properties for "BUILT-IN AUDIO" at 24/44.1 instead of 16/44.1. Darker background and better dynamics!!!


Enjoy and let me know your findings/likings.





Digital music addict[br]Mac G5 quad -> Apogee Duet -> Quad 303 (Planabox) -> Proac tablette 2000 -> Sweeeet bliss

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  • 3 months later...

Thank’s Kal.


One other thing I learned on the forum is that if you set the sampling rate at 88.2Khz in the AudioMidiSetup for the Duet, sound will just get better.


Tried it and it reallly makes the highs and mids smoother ;o)







Digital music addict[br]Mac G5 quad -> Apogee Duet -> Quad 303 (Planabox) -> Proac tablette 2000 -> Sweeeet bliss

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Dear Erik,


It is nice to meet someone using Duet as well.

Thank you for your tips.

I want to made sure that your recommended maestro setting eventually will be output to instrument amp, with Out L-R and max volume setting, am I correct?

For the setting to 88.2, is it only work for 44.1kHz music?

Do you have any good forum address talking Duet.


Mac Mini > iTune/ Amarra 2.2 > Threshold T2/ T400 X 2 > Silverlineaudio Grandeur II

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Yep, that’s it!


Just be careful with the "Out L-R" volume sliders: start at zero before you press play ;o)

Of course, you will loose any remote control action (if any) on the volume though…

I also use 96Khz setting with DVD playback (I’m not there yet concerning HDtv)


As for forums, I stopped looking when I found this one: the Duet community was not really active when I got mine.


Nice setup btw. I kind of miss the sub 35Hz with my Proacs.




Digital music addict[br]Mac G5 quad -> Apogee Duet -> Quad 303 (Planabox) -> Proac tablette 2000 -> Sweeeet bliss

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Dear Erik,


I still do not have time for serious listening to distinguish whether different Duet setting with affecting the sound quality.


But I think the setting may be individual, like in your case you do not have preamp.

Also, will you set all the slider all to maximum, I found that the red light of the indicator will be lighted sometime, ? distortion.

I got a preamp, so may be I should use the line out?

I suddenly realize the duet is a DAC with headphone amp, so in my case I should try to bypass that?


Unfortunately, i don't know how to find the ERS paper in Hong kong and can not try your tweak.


By the way, I have put all my music in a external hard disk and connected to my mac mini with USB cable.

I read from the web that the USB cable using in the connection of external hard disk will not affect the sound quality, is that real?


What firewire cable you are using to connect your Duet? Do you think it is significant?


Mac Mini > iTune/ Amarra 2.2 > Threshold T2/ T400 X 2 > Silverlineaudio Grandeur II

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Dear nghk,


I do not use the settings to max, because that would cause clipping (red light), either at the preamp stage in the duet and/or at my amplifier (and probaly resulting in destroying my ears and drivers!!) Some digital recordings are already inducing clipping as they possibly have been baddly engeneered and compressed to the extend of 0db (with no headroom) intendedly so they would sound LOUDER at playback. I sometimes have to set the "from software" sliders to -3db.


If I get that clear, you are using the headphone output to feed your preamp? This output has been intended to power headphones and the impedance of this output is in a pretty different scale than what your preamp is intended for. Nothing critical here as you won’t damage your pre. The good news though is that if you find 1/4 to RCA adaptors of good quality and plug them at the white squid in the line outputs, you might just be blown away by the difference!


For ERS paper, try http://www.partsconnexion.com/accessories_ers.html

I Think they would ship international.


I did try different firewire cables and heard no difference. The way data travels into firewire is through "packets" and there should be no jitter induced by the travel in the cable, only lenghts over 15 feet and interference in the power section should be a possible concern (I think… but I’m a just graphic artist so don’t take my word for it :o)


As for USB, it is about the same "architecture" of communication as firewire, meaning that it exchanges packets between external hardware (drive in your case) and the bus in the computer, still not supposed to unduce jitter or alter data.


The "transfer" by firewire or usb is different from toslink (Patented by Toshiba) or S/Pdif (Patented by a Sony and Pioneer Partnership) as it is free from jitter pollution: the data should arrive at the DAC chip in a "Bit Perfect" condition.


Having tried different dacs fed with either toslink or s/pdif (DIYed Monicas, Presonus, mAudio…), I felt that the firewire Dacs really rocks in comparaison.


I sincerely hope you will find some time to give it a chance with the line output and the settings we discussed in this post, or at least, time to just listen to music to your liking!


Take care,




P.s.: What are you listening to, on your side of the ball?




Digital music addict[br]Mac G5 quad -> Apogee Duet -> Quad 303 (Planabox) -> Proac tablette 2000 -> Sweeeet bliss

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dear Erik,


I am not using the headphone output.

I am using a handmade breakout wire.

I got the computer output plug from parts store.

I test the corresponding connection, then since I am using the Duet as a pure DAC now, I just self solder the corresponding pins to two RCA output and connecting my preamp.

Since I am "playing " Hifi for a long time, I got a old silverline connecting cable which my friend made for me as a "test" cable. the wire is rich in Silver and thin, so I just solder them to the plug. Although i am not good is this aspect, i believe should be much better than that breakout cable, which I need a lot connection.

So what are you using?


Actually, I am not sure about your setting of the Duet, what is the meaning of To instrument amp instead of line out, but some how since they disable the physical control by the duet, it may be good.

Since you do not have a preamp, so you are using the controller as volume control?


So how do you decide the level using in from software and to L-R?, by ear or calibrate carefully to avoid overloading?





Mac Mini > iTune/ Amarra 2.2 > Threshold T2/ T400 X 2 > Silverlineaudio Grandeur II

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You guys are using the Duet as a Firewire DAC and taking analog out into your amp, correct? Do you know if it's possible to get digital out of the Duet (S/PDIF or AES/EBU) and feed another DAC, thus using the Duet as a Firewire- to-whatever converter?


Mac Mini 5,1 [i5, 2.3 GHz, 8GB, Mavericks] w/ Roon -> Ethernet -> TP Link fiber conversion segment -> microRendu w/ LPS-1 -> Schiit Yggdrasil

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  • 1 month later...



thanks for the tip. i just finished to apply the ers paper as per your instructions.

it was easier getting mama on papa then mama off papa, but the sound improvements are amazing. the duet now sounds clear and open, making the listening more pleasant.


I am feeding an emmeline HR-2 by Ray Samuels Audio that powers my trusty AKG 701.


well done and many thanks again.






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