miniDSP 2x4 HD Sweetspot-audio Mod Review

[TheBatsEar]

He would like to know/verify

I wouldn't play "stille Post", it never ends well for the messenger, instead offer a registration link.

 

[Randolf]

The highlighted is a (rare but usual) horror story which a lot of people do not admit by the fear of not be able to sell their down the road gear and I think the few brave ones who report issues like that are a great help for the rest.

I'll say it once again for the rest,make sure that a protection scheme is down the road when using stuff that can default to 0db,it's not only about gear,gear come and goes,it's about damaged hearing by exposing the full force of a system in all it's glory.

(yep,once mote,let me be the paranoid one,even if I benefit a single person I'll be happy about it)

To be more precise, my DDRC-24 started losing its Master Volume and input selection (but not the Dirac Presets) after each power cycle coming up at 0db and RCA input. Which in my case was only annoying and not a disaster since I only use it at -10db and Toslink. I could temporarily fix it for some weeks by updating to the latest firmware before the problem reoccurred and finally the minidsp console doesn’t even recognized the device anymore. It was repaired (2 years warranty) without any not even shipping costs (Germany->Dealer in Netherlands->Hong Kong), but that took about 3 month. The minidsp and dealer support itself was excellent.

 

[caught gesture]

Wouldn’t it be better if Sweetspot were to send us his measurements. All this questioning of Amir’s measurement process, but no measurements from the person responsible for the “improvements” provided as a rebuttal.

 

[baron-bob]

Wouldn’t it be better if Sweetspot were to send us his measurements. All this questioning of Amir’s measurement process, but no measurements from the person responsible for the “improvements” provided as a rebuttal.

Sure, I agree. I would estimate that he would share the measurements from Gecom but I don't know. For now I will wait until further info from Amir and/or Sweetspot.

 

[baron-bob]

I wouldn't play "stille Post", it never ends well for the messenger, instead offer a registration link.

agreed of curse

He was thinking about registration, he wrote, but was not sure if it would make a difference or if he would find open ears because of the harsh climate towards him in thread.

 

[TheBatsEar]

You should record from the hw device.

Will do!

This is also the interface I use for rooPlay in my rooExtend suite.

Nice product. I'm not in the Roon ecosphere, but yours seems to be a nice addon

Recording in 32 bit is no issue.

Right. Got the samplerate under control too:

arecord --format S32_LE --rate=96000 --channels=4 --duration=5 --device=hw:CARD=Flex,DEV=0 hw.wav

 

[olieb]

agreed of curse

He was thinking about registration, he wrote, but was not sure if it would make a difference or if he would find open ears because of the harsh climate towards him in thread.

Well, if you don't try you will never know.
But defending a mod that nearly doubles the price and essentially only increases the noise of the device is obviously an uphill battle, I give him that. But delivering little bang for the buck is probably not that untypical for the modding business.

 

[ah-ra]

I contacted Sweetspot yesterday and already got a reply. I have to agree with Ah-ra that it would have been better to get a statement from him bevor publishing the review. It can indeed have a negativ impact on his business and therefore deserves a fair chance. He also wrote that he values all the hart and work Amir put's in to this site even dough he is no member.
.....

I fully agree. I think that's the best way to approach this. Let's see what Gecom Technologies will have to say to the original and the modded version.

I read that someone requested measurements from Sweetspot Audio but I have to agree that these would probably not be trusted on this forum after all the posts above. That's also a reason why I can understand not taking part in the discussion here. It's just not for everyone.

Therefore it is the best to have it tested by a third party.

I'm looking forward to the results.

PS: The questions he asked regarding the testing done by Amir are valid and he should also be able to re-test the unit himself.

 

[fordiebianco]

I had a look at Sweetspot's website, and there is a fair amount of audio woo. In their blurb for their modification of a Rotel RSP-1576 they suggest that replacing the rubber feet pads and the metal base sheet of the unit results in a 'purer sound (reiner Klang)'. Language like that usually is an automatic turn off for me.

 

[ah-ra]

I had a look at Sweetspot's website, and there is a fair amount of audio woo. In their blurb for their modification of a Rotel RSP-1576 they suggest that replacing the rubber feet pads and the metal base sheet of the unit results in a 'purer sound (reiner Klang)'. Language like that usually is an automatic turn off for me.

Agreed, but language like that can also be found on almost every Hi-Fi manufacturer's homepage...

 

[Deleted member 48726]

Thanks a lot Amirm for this review (an so many others). I am using a DDRC-24 since 20 month to bring DiracLive, which I found to be a very big improvement for my setup, into my Stereo system. It is a second generation device with the TI PCM3168A instead of AKM AK4626AVQ which was used in earlier devices. Perhaps Amirm compaired an unmodified AKM AK4626AVQ and a modified TI PCM3168A device or it is as it seems to be that the modification worsened the performance. Personally I would have not expected much of difference at all.

I know for sure that residual noise floor of a DDRC-24 is significantly to high to run it directly into a high gain power amp with high sensitivity speakers attached, this result in clearly audible hiss. But running it at -10db master volume (to safely avoid Dirac clipping) into an amplifier works pretty good. My device also had a critical fault after 14 month which caused it to startup at 0db master volume after each powercycle. Also taken into account that you cannot see the master volume from outside and there is no physical volume control I would never ever use it to control the volume.

For me (and I guees others as well) the open question is if I can find another DiracLive device (other minidsp, AV Receiver, Stereo Receiver) which really brings me an audible improvement in my setup.

Today I figured out that one can grap the DSP output of the minidsp via USB and after I figured out how to measure it's (purely digital) performance with REW accurately I am pretty confident one can pass it via USB/PC to whatever SPDIF or DAC device you want (see https://www.minidsp.com/forum/hardware-support/22596-2x4hd-ddrc-24-flex-recording-input ). Perhaps this helps some of the DDRC-24 or 2x4HD owners to do some nice direct A/B blind comparison (minidisp digital out+high end dac vs. minidsp RCA out, both with identical DiracLive filter settings). Perhaps someone can even measure it end to end with an expensive Audioanalyser.

Best regards
Randolf

I'm interested in knowing more about this digital sound extraction. Obviously you can't just connect the miniUSB to a DAC? -Is it doable without a PC in-between?

 

[mdsimon2]

I'm interested in knowing more about this digital sound extraction. Obviously you can't just connect the miniUSB to a DAC? -Is it doable without a PC in-between?

You need some sort of computer to redirect the processed signal to another output device. The link in my signature gives some example configurations of how to do this with CamillaDSP and a 2x4HD.

Michael

 

[Randolf]

I'm interested in knowing more about this digital sound extraction. Obviously you can't just connect the miniUSB to a DAC? -Is it doable without a PC in-between?

As mdsimon2 suggetsed, I guess you always need some kind of computer Mac, Windows, Linux, maybe as small as a RPi. I guess something like "arecord .... | aplay ...." can be used to grab the minidsp output and forward it to an SPDIF interface or DAC attached to the RPi, but I have zero RPi experience.

Yesterday I spent some time doing that via Windows "Listen" functionality. This way I was able to forward the minidsp digital output to a (rather inexpensive) Hifime DAC with USB isolator. The setup was:

Deezer Streaming(FLAC, 44khz, 16 Bit)-->WiiM PRO--(SPDIF)-->minidsp DDRC-24 (Dirac off, Master volume 0db)--(RCA)-->Yamaha AX-590-->Grado GS-1000i

vs.

Deezer Streaming(FLAC, 44khz, 16 Bit)-->WiiM PRO--(SPDIF)-->minidsp DDRC-24 (Dirac off, Master volume 0db)--(USB)-->Windows--(USB)-->Hifime Sabre 9018 DAC--(RCA)-->Yamaha AX-590-->Grado GS-1000i

I used the old AX-590 because it allows me to switch between both sources without any interruption for A/B testing, otherwise I would have used a R-N803D (very similar power amplifier), but that would cause ~0,5 sec interruption while switching.

I could not hear any audible difference, except a tiny little bit less hiss when using the Hifime Sabre 9018 (only audible when cranking up the Yamaha AX-590 volume to 0db, which is far far above useable with the Grado headphone).
There might be many reasons why I could hear any difference:

a) My hearing at the age of 58 may not be good enough and is not really trained to hear DAC differences (but quite experienced in comparing loudspeakers).
b) Source is just CD quality, so already limited to 96db. So maybe both DACs are just good enough for that.
c) DDRC-24 and Hifime DAC may be at a similar performance level, so not much of a difference to be expected.
d) DDRC-24 is probably resampling everything to 48khz (at least in Dirac mode).
e) Windows sound engine is involved.
f) Driving low impedance Grado GS-1000i via integrated amplifier is not ideal (high output impedance, due to resistor in headphone output, fortunately GS-1000i has an almost flat impedance curve)

 

[Deleted member 48726]

As mdsimon2 suggetsed, I guess you always need some kind of computer Mac, Windows, Linux, maybe as small as a RPi. I guess something like "arecord .... | aplay ...." can be used to grab the minidsp output and forward it to an SPDIF interface or DAC attached to the RPi, but I have zero RPi experience.

Yesterday I spent some time doing that via Windows "Listen" functionality. This way I was able to forward the minidsp digital output to a (rather inexpensive) Hifime DAC with USB isolator. The setup was:

Deezer Streaming(FLAC, 44khz, 16 Bit)-->WiiM PRO--(SPDIF)-->minidsp DDRC-24 (Dirac off, Master volume 0db)--(RCA)-->Yamaha AX-590-->Grado GS-1000i

vs.

Deezer Streaming(FLAC, 44khz, 16 Bit)-->WiiM PRO--(SPDIF)-->minidsp DDRC-24 (Dirac off, Master volume 0db)--(USB)-->Windows--(USB)-->Hifime Sabre 9018 DAC--(RCA)-->Yamaha AX-590-->Grado GS-1000i

I used the old AX-590 because it allows me to switch between both sources without any interruption for A/B testing, otherwise I would have used a R-N803D (very similar power amplifier), but that would cause ~0,5 sec interruption while switching.

I could not hear any audible difference, except a tiny little bit less hiss when using the Hifime Sabre 9018 (only audible when cranking up the Yamaha AX-590 volume to 0db, which is far far above useable with the Grado headphone).
There might be many reasons why I could hear any difference:

a) My hearing at the age of 58 may not be good enough and is not really trained to hear DAC differences (but quite experienced in comparing loudspeakers).
b) Source is just CD quality, so already limited to 96db. So maybe both DACs are just good enough for that.
c) DDRC-24 and Hifime DAC may be at a similar performance level, so not much of a difference to be expected.
d) DDRC-24 is probably resampling everything to 48khz (at least in Dirac mode).
e) Windows sound engine is involved.
f) Driving low impedance Grado GS-1000i via integrated amplifier is not ideal (high output impedance, due to resistor in headphone output, fortunately GS-1000i has an almost flat impedance curve)

Thanks.

I'm certain I wouldn't hear any difference what so ever between the miniDSP and a -130 dB topping DAC. It's more of an interest in what's possible than anything else.

 

[TheBatsEar]

language like that can also be found on almost every Hi-Fi manufacturer's homepage...

There are plenty of respectable companies out there that do an excellent job at not pulling BS out of thin air. They usually are led by rational, measurement driven people that avoid claims that aren't evidence based.

In my opinion "they all do it anyway so it's ok" is a bad excuse and i for one don't accept it.
It devalues the work of the companies that do good work (and keep their marketing people in line ).

 

[Toni Mas]

Honnestly i dont find that the mods degrade performance. It is true that the noise is marginally imcreased (totally harmless), but this comes with a significant reduction of harmonic above H2. Once again i find noise an overated parameter.

 

[MAB]

Honnestly i dont find that the mods degrade performance. It is true that the noise is marginally imcreased (totally harmless), but this comes with a significant reduction of harmonic above H2. Once again i find noise an overated parameter.

While I generally agree, so many active speakers hiss. I think HD is overrated since so many of us fail to be able to hear distortion until it is large.
I sure can hear noise, although we can argue if it interferes with anything but quiet passages. I showed noise-audibility on the PA5II thread, although the DAC was SOTA. Would have been interesting to see how much worse a 2x4 and a Sweetspot audio version would have degraded!

 

[Toni Mas]

While I generally agree, so many active speakers hiss. I think HD is overrated since so many of us fail to be able to hear distortion until it is large.
I sure can hear noise, although we can argue if it interferes with anything but quiet passages. I showed noise-audibility on the PA5II thread, although the DAC was SOTA. Would have been interesting to see how much worse a 2x4 and a Sweetspot audio version would have degraded!

Maybe i dont understand, but a passive resistive attenuator between the amp and this too efficient driver would do the trick, as usually do all passive xovers...

Paying a Purify simply for this seems a bit overkill for me...

 

[MAB]

Maybe i dont understand, but a passive resistive attenuator between the amp and this too efficient driver would do the trick, as usually do all passive xovers...

Paying a Purify simply for this seems a bit overkill for me...

You are right. I demonstrate that in the post as well (a filter capacitor is effective).
I agree with your point about audibility of HD, just wanted to point out that noise matters as well, especially in the application this device is used. I risk missing the big point, the modifications to this cost more than getting a DSP crossover with more DSP capability, which is absurd. You and I are talking about second order effects here... This modified device is practically inaudibly worse than the original, it's the added cost that is offensive.

 

[Toni Mas]

You are right. I demonstrate that in the post as well (a filter capacitor is effective).
I agree with your point about audibility of HD, just wanted to point out that noise matters as well, especially in the application this device is used. I risk missing the big point, the modifications to this cost more than getting a DSP crossover with more DSP capability, which is absurd. You and I are talking about second order effects here... This modified device is practically inaudibly worse than the original, it's the added cost that is offensive.

Of course i agree It makes little sense to pay for this small upgrade.