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MiniDSP HA-DSP Discussion and Impressions

Discussion in 'Portable Headphone Amps' started by Velozity, Sep 14, 2017.
  1. Velozity
    I'm surprised that this piece hasn't been discussed on here yet. I'm a proud new owner and I wanted to share a little bit about it. I'm really impressed with it so far. As a car / home audio fanatic I am very familiar with DSPs in general. When I found out a portable headamp existed with DSP built-in I jumped on it. As I get to use it more I will post more impressions. For now here are a few pictures and features. I'll post some screenshots of the software a bit later.

    The highlights we care about:
    • Portable DAC / Amp utilizing ESS Sabre ES9018K2M 32-bit DAC
    • Amplification via TI TPA6120A2 chip- max 100 mW / ch at 32 ohms
    • 3300 mAh battery, fast charge capable
    • Asynchronous USB 2.0 controller
    • 400 MHz floating-point SHARC processor (the real magic of this piece)
    • 3.5 mm combo analog / mini-toslink digital input
    • DSD capable
    • 4 DSP presets
    • Aluminum housing


    abm0, Alexdre119 and headdict like this.
  2. macro
    I get the impression a lot of people in the headphone community (and Head-Fi in particular) tend to shy away from signal processing either because they're purists or they just don't know how to implement it properly.

    I'm with you, though. I'm also passionate about home theater and car audio where signal processing is pretty much a necessity, so I'm definitely not afraid of EQing my headphones. I've been wishing for a system wide EQ solution for my iPhone for years.

    From what I've seen, miniDSP has a solid reputation. This one looks promising albeit a little bulky. I could see myself potentially using one on long flights, but it's definitely too big for my everyday carry. Looking forward to some more in-depth impressions! Also wondering if you can tweak your equalizer settings on the go with an iPhone app.
    Last edited: Sep 23, 2017
    Velozity likes this.
  3. Velozity
    You're right in your impression, but I also think a major reason more people don't gravitate to DSP solutions is because quite frankly there just aren't that many. I'm hoping with MiniDSP's release that other manufacturers follow suit. It would be absolutely amazing for a portable dacamp with the quality of a Chord Mojo to incorporate DSP. Maybe incorporate it into the new Poly streaming module and have it controlled by the smartphone app...(hint, hint Chord).

    Many people also have to get over the thought that using EQ is somehow a bad thing. We all know every speaker is different and all our hearing is different. In the car audio world EQ is a necessity to overcome the sound quality robbing effects of the listening environment. EQ can be equally beneficial to head-fi users to overcome deficiencies in frequency response for any number of reasons. I use the Kaiser Tone hi-res app as the media player for my iDevices. The EQ capabilities are second to none in my opinion.

    The thing I'm most interested to try on this HA-DSP (and sadly haven't had time yet) is the implementation of crossfeed algorithms. The ability to make listening to headphones sound more like listening to a pair of home speakers is extremely exciting.
    Last edited: Sep 25, 2017
    headdict likes this.
  4. tmuka
  5. macro
    Some more info I obtained via email for those who might be interested:
    The high output impedance obviously isn't ideal for a lot of low impedance portable headphones and especially multi-driver earphones with large impedance swings, although I imagine the equalization functionality of the MiniDSP could at least correct any frequency response imbalances the high Zout might cause.
    Last edited: Nov 1, 2017
    tmuka likes this.
  6. HiFiChris Contributor
    I'm somewhat surprised that it didn't really get any notable attention on Head-Fi as well. I guess it might come down to two things - 1) as mentioned, some people think that everything related to EQ and DSP is a "bad thing", and 2) people don't really know how to properly use EQs and DSPs.

    May I ask what the little switch on the back is for?
    And how do you load presets onto the HA-DSP (what software is required, what can be done, how many filters can be set, is the EQ fully parametric)? Could you probably even provide a screenshot of the interface?

    Anyway, I am glad and excited to see that their EverAMP idea that was announced a couple years ago is finally in production in form of the HA-DSP. And their just-announced EARS headphone and in-ear measurement station looks very exciting as well.
    kukkurovaca and tmuka like this.
  7. tmuka
    I think you're right about knowledge of how to configure DSP being a deterrent to some users for this type of device. The pc config software UI looks similar to my C-DSP. You can see a few pictures of it in the manual PDF on page 23, 30. https://www.minidsp.com/images/documents/HA-DSP User Manual.pdf

    From the manual, it looks like the rear switch changes the USB max charging speed, or possibly usb device mode for use with a usb hub, probably to reduce excessive power draw on mobile devices. It's not stated very explicitly, only mostly to leave it on position 1 trickle charging, or position 2 for faster charging.

    They probably also released the EARS measurement station along side this since that opens up the possibility of letting software do the math to configure the DSP corrections. At least in my car's miniDSP C-DSP, there are both input and output corrections available, so you can configure the output eq to set the speakers as flat as possible (better speakers enable more corrections) then you can setup the input eq with your preferred "house curve" for your listening preferences, eg, V shaped, sloped down toward treble or bass, etc... I use their calibrated mic and Room EQ wizard to generate the ideal pEQ settings. It looks like the HA-DSP has some even more advanced features for using FIR (impulse responses) which goes a step further than eq into being able to also alter the timing per frequency at a very low level, at various amplitudes, eg to make your bass tighter (if your phones can do it) or looser, etc.

    I don't have any connection with miniDSP except as a very satisfied customer of their C-DSP. I think there is a big technical divide between some of the amazing analog amp/dac designers (whom i greatly respect!), and those who additionally understand how to write code to take advantage of modern advances. I think the future will be rich with DSP.
    hqssui, HiFiChris and kukkurovaca like this.
  8. HiFiChris Contributor
    Thanks for your detailed reply, mate!
  9. Velozity
    I'll try to find some time this weekend to post some screenshots of the UI to show exactly what it does. As far as the switch on the back, miniDSP has said to always leave it in position 2. I'm not sure exactly what it does. I think it's there for future updates. I don't see where it says position 1 is trickle charging... Regarding the EQ, yes is fully parametric with 10 bands per left and right channel. On top of that there's bass and treble input controls for each channel. The center frequencies are adjustable from 200Hz-750Hz (bass) and 750Hz-3000Hz (treble).
    tmuka and HiFiChris like this.
  10. tmuka
    yeah, sorry, it looks like I got the wrong idea about the switch from the manual where it was talking about USB hubs possibly being slower to charge. interesting and weird they don't actually define the purpose of the switch!
  11. m8o
    To anyone that has this, what is the analog output stage like? With the programmable dsp supplementing the dac, form factor, it seems the 'cost' only allows for a fiio e17k alpen level amp.

    Not disparaging the FiiO ... I bought two. But I've also moved on to much better things. Will this portable dsp + dac + amp 'impress'?
    Last edited: Feb 13, 2018
  12. PantsUK
    Hi Guys,

    By all means let me know I'm being an idiot but could I be correct in thinking the following is potentially possible to a degree at least. (Not necessarily with this unit perhaps one of mini dsps others like the mini dsp 2x4 HD) You could record a sound using the EARS tool utilising your own setup so minidsp to own amp to own headphones and then DSP correct it to a flat response (assuming the headphone drivers were high enough quality to do this of course) and then alter the output to become another headphone/amp setup all together different? So for example I have the HE400i planars and the Philips X2s, assuming the drivers would be capable could I record the sound from the X2s and then make the HE400i sound similar to this. Equally could it be possible that a friend of mine has a totally different amp/headphone setup, again we record the sound from his and then it would be possible to have a similar sound but on different kit? Tube sound on Solid State kit for example? My terminology I'm sure is incorrect but essentially could a headphone reviewer for example record the audio signature from a range of headphones and then you as the consumer be able to try that sound out on your own kit? Clearly the quality of the existing equipment would need to be of a standard I'm not suggesting a pair of apple earbuds is ever going to sound like a Senn' HE-1 :wink: I'll put my flameproof trousers on :D
  13. kukkurovaca
    Well, you can certainly use this (or parametric eq in software) to modify the frequency response of one headphone to sound another. And if your tube gear is emphasizing certain frequencies, you can duplicate that aspect, too.

    Lots of other stuff goes into the sound of a headphone or amplifier, however. Speed, dynamic range, distortion, detail reproduction, soundstage, etc.

    Also, from what I read of initial impressions of the EARS on a different forum, it sounds like heavy calibration and/or modification might be needed to get consistent and accurate measurements.
  14. abm0
    First of all, you can't reproduce all of the audible qualities of a headphone using another headphone because most of them are based on the physical properties of the target headphone and you can't do the same thing with a very different physical system, like you can't have someone reproduce olympic performance with a completely un-trained and unsuitable body.

    You can get pretty good results in terms of frequency response if you equalize a headphone with very low distortion (i.e. a planar, either magnetic or electrostatic, or some equivalent ToTL dynamic) to imitate a lower-quality headphone, but not the other way around. You try to boost a frequency range where your headphone has hard limitations and lots of distortion, you will start to hear that distortion and it will ruin the sound instead of imitating the target.

    And then there's the issue of how much the frequency response varies just based on how you seat a pair of headphones on your head (or on the measuring "head") or how good of a seal you can get, or how worn the pads are etc. That's bound to make the process quite random and to make the results vary by a lot.
  15. PantsUK
    It would seem the quality of the driver itself is the biggest factor and I guess that's where I was coming from. Take the T50rp for example which has been modded to death, clearly the driver is capable of much more than it produces as standard how much of that is due to the tuning of the driver sound signature and how much is due to the housing/pads etc? I appreciate this point "You try to boost a frequency range where your headphone has hard limitations and lots of distortion, you will start to hear that distortion and it will ruin the sound instead of imitating the target." I've done that plenty of times :D but I wonder if you could produce close to the house sound of say Beyer on a 400i. I appreciate the variables would never be exact, the same as listening to headphone sound demos on a different set of headphones but perhaps it could be a more accurate way of listening to the "core" sound signature than the headphone to headphone inception?

    I would imagine if you had a consistent test setup (ie the recording head represents you the wearer closely) so you can flatline the sound of your original headphones then any future adjustments assuming they were within the range of the driver capabilities would be a reasonable reflection of the sound signature of a different headphone..... in my head it makes sense at least :wink:

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