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rjm rjm is offline

Richard Murdey

diyAudio Member

About Me

  • About rjm
    Canadian citizen, Japanese resident.
    Audio Circuitry
    Research Scientist
    Real Name
    Richard Murdey
  • Signature
    RJM Audio ( / G+)


Total Posts
General Information
  • Last Activity: Today 08:31 AM
  • Join Date: 2nd May 2004


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View rjm's BlogRecent Entries
Latest Blog Entry

Posted 30th October 2015 at 01:49 PM by rjm Comments 7
Original version is here.

I've been meaning to get around to updating this by folding in the improvements to the diamond buffer stage made during development of the Sapphire 3 headphone amplifier. Here is the first look of the bboard v2 under LTSpice.

I've gone back to simple emitter resistors on the input, running under much lower current to keep the input impedance high. The output is simplified to a basic Sziklai compound transistor pair with the bulk of the bias current running in the second transistor.

In terms of distortion, for line level output level, CCS loaded input has no advantage. I'll have to double-check PSRR and a few other things before signing off on this version though.

FYI only, not a production circuit.

Posted 9th October 2015 at 11:46 PM by rjm Comments 0

I admit I did not give ASUS the benefit of the doubt and seriously consider their Essence STX soundcard as a replacement for my Onkyo SE200-PCI. ASUS make nice motherboards, but unlike Onkyo have no previous expertise in high end audio.

I am happy to report - a bit late in the game, the card came out in 2009 - that they've done a really good job with it and the drivers for Windows 10, technically still in beta, work just fine.


Asus updated the design recently to the STX II. The PCB has been redone, but the only visible change is the PCM1792A DAC has been moved towards the top of the card closer to the IV conversion op amps. An second LDO regulator IC, U34, empty on the STX, is now populated. A "TXCO" clock source is added next to the ASUS audio controller IC. The four film caps next to the output IC are replaced with WIMA brand. It's basically identical, so it...

Posted 8th October 2015 at 08:35 AM by rjm Comments 3
Apologies for the Google-friendly title, I'm hoping people experiencing the same problem will find their way here.

Onkyo download page:

Current version is 5.60C, last update was 2012 to be compatible with Windows 8. Driver package 5.60C installs without issues on Windows 10 64 bit. The AudioDeck utility installs as well.

However, all is not well:

On installation, Immezio 3D effects are enabled. This locks the sample rate at 48 kHz. 44, 96, and 192 kHz cannot be selected. Deselecting the Immezio 3D effects prompts a reboot, but the Immezio 3D effects remain enabled after rebooting. The card is stuck at 48 kHz. 3D effects (which enables the DSP processing such as Qsounds, EAX, A3D) cannot be shut off.

I see three possible workarounds:

1. Find a command line switch, or edit the installation batch file to disable Immezio 3D on installation...

Posted 2nd October 2015 at 06:07 AM by rjm Comments 0
This is a headphone amplifier with digital inputs, not a DAC with a headphone jack. Though technically given equal board space, the headphone amp, with hot-running single-ended class-A output stage, is surely the centerpiece of the design. (The Asahi Kasei DAC, with MUSES01 for the I-V, is no slouch mind you.)

First impressions. It is large, solid, and very nicely made, but - after seeing the inside - rather simple, spartan even. From the DAC output to the headphone jack is just two op amps and two transistors, the op amps being shared between channels. A third op amp most likely just buffers the analog line output. Apart from the headliner MUSES01 op amp none of the parts are especially expensive, though many were clearly carefully chosen for sound quality - the 2SC5196 for example. The TE7022 USB receiver is a disappointment, as is, to be honest, the single set of power rails and the use of dual op amps shared between channels.

On a positive note, the front...

Posted 26th September 2015 at 12:49 PM by rjm Comments 5
My Onkyo soundcard drivers stopped working when I upgraded to Windows 10. Onkyo says they have no plans to release a patch, so I'm left with no high quality audio solution for my computer. Since I already have a good headphone amplifier, what I'm mainly looking for is a high quality line level analog output.

One options is another soundcard, the ASUS Xonar STX being the obvious choice. I dunno, it doesn't grab me.
I was thinking with going with an external box this time, connected via USB. As this opens up about a zillion options, I'm going to limit things to,
  1. Respected audio brands with a solid reputation for digital audio.
  2. Small enough to be placed on top of my computer case.
  3. $500-ish, used or new.
My short list includes the following: Denon DA-300usb, TEAC UD-301, and Onkyo DA-1000. Teac also makes the 301's big brother, the UD-501. This is a much nicer unit, very substantial. A bit large. Rounding out the field is the LUXMAN DA-100 . These can be found deeply...
Recent Comments
Ah - that's a good point,...
Posted 10th November 2015 at 01:47 PM by abraxalito abraxalito is offline
Increasing the impedance...
Posted 10th November 2015 at 12:38 AM by rjm rjm is offline
Here's a crazy notion...
Posted 6th November 2015 at 02:17 AM by abraxalito abraxalito is offline
I've had a chance to...
Posted 5th November 2015 at 01:32 AM by rjm rjm is offline
Yep, I meant C1,2. They...
Posted 4th November 2015 at 01:15 PM by abraxalito abraxalito is offline
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