Introducing the Matrix M-Stage HPA-3U and HPA-3B, review to follow!

Discussion in 'Headphone Amps (full-size)' started by keanex, Jun 5, 2015.
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  1. gLer
    Hi, and thanks for your reply. The ZMF Atticus is actually a customer made TPE dynamic driver, not one of the Fostex mods. I’m sure the Matrix will drive it easily, just wondering about the synergy as the Atticus is said to favour tubes with its 300ohm impedance.
  2. raoultrifan
    Hi gLer, sorry for the missinfo!
    I was reading now Tyll's article about the TPE custom drivers, hence...let's wait for a headfier that actually tried these headphones on a solid-state amp.

    P.S.: Don't know if it counts, but my 600-ohms Beyers DT880 are easily driven by this amp.
    Last edited by a moderator: Nov 19, 2017
  3. gLer
    No probs, ZMF's newer headphones probably aren't as well known as I assumed :) Well worth a listen if you get a chance. I'll be able to give my impressions when I get mine, was just wondering if any current 3B owners have tried them out.
  4. loserica
    After the complete burn-in seems to have no connection with the stock unit, except the tone that is somewhere in the same area. It is significantly improved the speed, the timing, decay, resolution and sound-stage becomes so generous in depth!! (excelent layering). The stock unit was so anemic and unmusical comparative to the one I propose. It is something else. Everything makes sense by the fact that the sound is airy, fleshy, reliable with a transparency and those micro-details and texture which reminds me of the electrostatic system Stax&eXStatA (keeping the proportions still: control, focused image and superior texture for electrostatics).:deadhorse:

    Slowly, slowly I have the feeling of disappearance of the headphones on my ears which brings back the emotion that frankly speaking lacking before. If you ask me if it was worth the wait for the complete burn-in (I think over 600/650 hours), my only answer is this one: it sounds incredible for the price I paid!
    Last edited: Dec 17, 2017
  5. CharlesC
    Is the HPA-3U+ listed on the Matrix website the same device as the HPA-3U discussed here? My first guess is that it is a recent upgrade but I can't find any separate information on it or how it is different. Thanks.
  6. trybeingarun
    The dac chip has changed b/w the two editions. Rest of it is exactly the same.
    CharlesC likes this.
  7. CharlesC
    I went ahead and ordered these. At about half the price of the Deckard ( after holiday discount ) I couldn't resist. I've got brand new LCD2-Classic headphones. I've been running them off my Dragonfly Red for a few days. I figure I'll have the option of running the DfR (2.1v line level) into the analog input on these if I want to. Still waiting for shipping confirmation though so don't let me get too excited.
    Liu Junyuan and trybeingarun like this.
  8. winja
    I just want to drop in and say that I like my HPA-3B and the Hd800 a lot. I can hear lots of little details and nuances such as the flicking of guitar strings, vibrations of the violin bows, etc. Instrument separation and soundstage are also very good. Vocal is clean. The HPA-3B is a touch warm, and it pairs well with the hd800 when it comes to the treble peak. I have no listening fatigue even after listening to the combo for hours.
  9. trybeingarun
    Which dac are you using to go along with the rest of the setup?
  10. winja
    I pair the HPA-3B with my Yggdrasil. The Yggdrasil is in another league of its own, but that just to say the HPA-3B is capable of revealing details if it is fed by a good source.
  11. UpTo11
    Did someone listen to the MrSpeakers Aeon Flow (open or closed) with the HPA-3B amp? I would like to know about this match. Thanks!
  12. raoultrifan
    16 ohms headphones, right? HPA-3B has an output impedance of 0.4 ohms in single-ended operation, so the dumping ratio should be very good with Aeon.
    Being a Class-A amplifier means that will drive dynamic and planar as well, with ease, so I see no issue in driving the Aeon headset.
    Also, the low-gain (1st position on the knob switch) would probably be perfect for these headphones.
  13. UpTo11
    13 ohms impedance, 92dB (closed) - 94dB (open) sensitivity. While these numbers are good for the HPA-3B, at least on the balanced output, I'm looking for comments on this match beyond bare numbers. Anyway thanks for the answer.
  14. raoultrifan
  15. raoultrifan
    Not much activity around here lately. :)

    However, after more than 2 years of service I'm still enjoying my HPA-3B headamp, especially that I did some more mods recently to increase it's performance by:
    1. Cutting backside PCB traces from the XLR plugs to the input caps, then further to the ALPS 4-gang potentiometer and getting the audio signal through good quality copper shielded wires. This way hiss and noise decreased a little bit; after all, I'm speaking of more than 20 cm of PCB traces (on expensive amplifiers input potentiometer is positioned nearby the XLR plugs and a metallic extender from the volume knob is used to adjust the volume).
    2. Swapped 2 x BURSON V6 Classic opamps with 2 x OPA1652 installed on DIY SOIC-DIP8 adapters to further decrease background noise (some noise was audible only when using high sensitivity cans combined with highest gain setting of +20 dB). It's not much of a difference the 2 opamps, but there's a slight barely audible improvement (it's easier do check when swapping only 1 opamp only, then left headphone will have a different hiss/noise vs. the right one).
    3. Increased treble roll-off frequency from 20 kHz to about infinite by completely removing the Low-Pass filter. Not quite recommended because some input sources might oscillate and deliver ultrasonic sounds, but in my case I'm safe...I know what DACs I got at home.
    4. Decreased bass roll-off frequency a little bit by replacing the 50 kOhms input XLR resistors with 150 kOhms resistors (there's a high pass filter created by resistors and input caps). Ideally would be not to touch these resistors, instead to swap the input 2.2 uF caps, but I couldn't insert bigger caps inside the HPA-3B case...maybe some other time will do that too.
    5. There was a slight channel imbalance no matter the gain I used, so I had also resolved this from the gain stage from nearby the 2 opamps. Basically, there are 4 x resistors (around 5.4 kOhms each) that are connected between pins 2/6 and GND for each opamp, so decreasing a little bit these resistors will increase amplifier's gain. I did that by adding in parallel 4 more resistors (48 kOhms each) on the back of the PCB.
    Transformer shielding plus the first 2 mods from above decreased hiss and hum to half.
    The 5th mod equalized levels almost perfectly to both channels on balanced and on unbalanced too.

    As for the mods 3 and 4, these only "affects" beginning and ending of the audio spectrum only, so please check below pics:

    Sine_2kHz.png Square_1kHz.png
    The above 2 pics show a perfect sine-wave 2kHz and a perfect square-wave @1kHz. There's nothing to improve here, perfect shape, latency, no phase issue.
    Channel A (blue) is the original signal, channel B (red) is what HPA-3B is throwing on the 6.3 mm headphones plug.

    Sine_20kHz_before_LPF_mod.png Sine_20kHz_after_LPF_mod.png
    The 2 pics above show a 20 kHz sine signal: left - before the low pass filter removal, right after LPF removal. On the left there's a slight latency on the red channel (the HPA-3B amplifier).

    Sine_100kHz_before_LPF_mod.png Sine_100kHz_after_LPF_mod.png
    Above is the representation of a 100 kHz sine-wave: left - the original unmodified HPA-3B, right - after LPF caps have been removed. Almost perfect inline with the blue channel.

    Square_20kHz@Gain_0dB.png Square_20kHz_after_LPF_mod.png
    Representation of a 20 kHz square-wave: left - original HPA-3B, right - after LPF mod. Here difference is quite huge; I know many might say that square waves are nothing to do with audio, but we all know that with square waves manufacturers are actually testing their amplifiers for imperfections.

    Square_20Hz_before_High_Pass_mod.png Square_20Hz@2.2uF+150kOhm.png Square_20Hz_after_cap.png
    Representation of a 20 Hz square signal: left - the unmodified HPA-3B, middle - after the high pass filter mod, right - signal applied after the 2.2 uF input caps. Everyone knows that "best cap is no cap" when dealing with caps into the audio path, so the 3rd image proves that. However, I'll be keeping the 2.2 uF caps in my HPA-3B just in case I'll connect a DAC with high DC-voltage.

    PCB traces cut and replaced with shielded wires. This is the audio signal path coming from the XLR plugs and is having about 20 cm!

    Input high-pass filter created by the caps and resistor; also input impedance is done here.

    Low-pass filter caps: C29, C30, C31, C32.
    Last edited: Mar 12, 2018
    bunkbail and canthearyou like this.
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