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Minidsp SHD Review Updated (DSP, DAC & Streamer)

nothingman

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Really happy with my SHD purchase so far (October 2020, so I guess I have the latest hardware). I have a few gripes like others but you can't argue with the level of audio performance, inputs, and DSP customization in this unit for $1200.

Tell me if I'm crazy, but the one thing that keeps cropping up for me is the 4V max output. Without Dirac, I don't think it's really a problem, but it becomes one with Dirac enabled which, per the manual, means you shouldn't bring the volume above -10db because you need to give Dirac that much room to guarantee it won't clip while boosting frequencies. -10db is more of a voltage drop than you might think, especially when your source signal is nowhere near approaching full strength.

For many recordings, even -10db louder than I'd normally listen, but for quiet signals, I need more voltage going to the amp. Given the limitations that running Dirac introduces, the SHD should probably be capable of something like 8V so that we don't take as much of a hit by the -10db volume limitation. Basically what would be nice is a unit that could produce ~8V but then have a low-gain/high-gain setting for folks who want the max SNR and then those of us needing some extra juice. Since something like the Benchmark DAC3 outputs 12v(+24dbu) at 0db, I don't think I'm way off base here. Again, tell me if I'm crazy.

I know this partly comes down to amp power and speaker sensitivity, but I'm using mainstream stuff here. Amp sensitivity is rated at 185w/8ohm @ 1.43v input (NAD C298), and JA's sensitivity measurement on the speaker is 84.5db (LS50 Meta).
 

sarumbear

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with Dirac enabled which, per the manual, means you shouldn't bring the volume above -10db because you need to give Dirac that much room to guarantee it won't clip while boosting frequencies. [...] Amp sensitivity is rated at 185w/8ohm @ 1.43v input (NAD C298)

As far as I can see your issue is lack of power reserve. It has nothing to do with the maximum output of SHD.

If you need to boost a range of the audio by 10 dB you then need an equivalent amount of power headroom. Otherwise, as you complain, you have to listen to a lower volume, so that just in case the 10 dB boosted range is in the music material, power amplifier will not clip. In other words your 185 W amplifier becomes a 18.5 W one.

That is not an issue about SHD, nor Dirac. It is about equalisation.
 

Xyrium

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Any measurements?

I used to use the 260 as a PEQ and active Xover for my Zaph ZRTs and subs. It worked well overall, and was made in the USA at the time (10 yrs ago) if that matters to some Westerners. That said, I don't believe that you can use the 360 as a USB DAC, but perhaps some sort of USB to AES converter could work.
 

nothingman

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As far as I can see your issue is lack of power reserve. It has nothing to do with the maximum output of SHD.

If you need to boost a range of the audio by 10 dB you then need an equivalent amount of power headroom. Otherwise, as you complain, you have to listen to a lower volume, so that just in case the 10 dB boosted range is in the music material, power amplifier will not clip. In other words your 185 W amplifier becomes a 18.5 W one.

That is not an issue about SHD, nor Dirac. It is about equalisation.

I think we’re agreeing with each other on the premise that you need to provide the headroom, but you say “so that the power amplifier will not clip” and I think that’s wrong. The issue is up the chain at the SHD: as I understand it, limiting the volume to -10db is for the purpose of not having the SHD clip. Instead of making it about the amp power rating, I would say it’s more accurate to say my 4V max ouput preamp is being limited to something like 1.25V, and therefore it is a matter of the SHD’s max output spec and how that is affected by Dirac. If the SHD wouldn’t clip until much higher, then you could drop -10db and sill be in the sweet spot on voltage output.
 

Jerry Sobel

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Help! This is as good a place to ask my question since we are on the topic of minidsp. I own the DDRC 88A and have had it running without hiccups for the last few years. I finally decided to upgrade to the new Dirac Live as I have been running the legacy version of 1.0. Part of the upgrade was to upgrade the firmware. I read the instructions over and over so as to not screw it up. Well, I screwed it up. I clicked on the wrong firmware update (not sure why there two different ones given) and now my unit is bricked. I cannot get back into it. I have reached out in the MiniDSP forums and even sent a support ticket and I cannot get a response back. I found online a way to reset the firmware but it was on an older unit. Any suggestions or ideas on how to reset the unit so I can load the correct firmware or am I S.O.L!!!
 

dominikz

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I think we’re agreeing with each other on the premise that you need to provide the headroom, but you say “so that the power amplifier will not clip” and I think that’s wrong. The issue is up the chain at the SHD: as I understand it, limiting the volume to -10db is for the purpose of not having the SHD clip. Instead of making it about the amp power rating, I would say it’s more accurate to say my 4V max ouput preamp is being limited to something like 1.25V, and therefore it is a matter of the SHD’s max output spec and how that is affected by Dirac. If the SHD wouldn’t clip until much higher, then you could drop -10db and sill be in the sweet spot on voltage output.

Full disclosure - I don't own the SHD, but have tested Dirac Live PC VST plugin.

I assume the reason why ~10dB headroom is required in SHD is because Dirac can boost some frequencies by ~10dB. I.e. your average signal going to the amp will be ~10dB lower, but there will still be peaks at full-scale output when the signal hits frequencies Dirac boosted. Note that you also don't want the amplifier input stage to clip in those cases.
So IMHO @sarumbear is correct when he says the limiting factor will be amplifier power headroom rather than SHD output voltage. SHD will only lose about 10dB of SNR due to 10dB lower average output level.

Side note - won't Dirac processing in SHD itself reserve the headroom and lower the volume, rather than the user having to reduce SHD master volume?
 
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xykreinov

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I was looking at a thread on another forum where a guy was talking about how a particular combo of mains and speaker cable made a "significant" difference to his system. To these people a box like the SHD would be anathema, because it would "degrade the signal" or something. They prefer an imaginary difference to a real one!!
Wild.
I also always get a kick out of people who think EQ inherently colorizes the sound... As if analog is somehow more "natural" and therefore more neutral.
 

Kachda

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Side note - won't Dirac processing in SHD itself reserve the headroom and lower the volume, rather than the user having to reduce SHD master volume?

This is my understanding as well..the internal processing in the minidsp shd reduces the signal by 10db in order to apply boosts to dips. So you can still go up to 0db on the minidsp SHD, but that does not mean it is outputting a 4V signal over XLR/2V over RCA. I don't know if the minidsp does this, but as someone mentioned, it would have been good if the minidsp compensated for DIRAC by applying some gain.

I have a NC502MP based amp (350W@8ohms, 500@4ohms), and for music I keep the volume around -22db to get ~75db volume at 5 feet from the speakers ! My understanding is that NC502MP does only 26db gain over unbalanced and 20db over balanced though, so part of the problem is the low gain of the amplifier.
 

nothingman

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Full disclosure - I don't own the SHD, but have tested Dirac Live PC VST plugin.

I assume the reason why ~10dB headroom is required in SHD is because Dirac can boost some frequencies by ~10dB. I.e. your average signal going to the amp will be ~10dB lower, but there will still be peaks at full-scale output when the signal hits frequencies Dirac boosted. Note that you also don't want the amplifier input stage to clip in those cases.
So IMHO @sarumbear is correct when he says the limiting factor will be amplifier power headroom rather than SHD output voltage. SHD will only lose about 10dB of SNR due to 10dB lower average output level.

Side note - won't Dirac processing in SHD itself reserve the headroom and lower the volume, rather than the user having to reduce SHD master volume?

Second part first: no, there is no automatic governing by the SHD. The manual states that it’s up to the user to keep the volume at -10db or below while Dirac is enabled.

We all agree on why the -10db volume setting is there. Yes, it’s because Dirac may boost some frequencies up to 0db.

But, when 0db out of the SHD is at most 4V (requires 0db input signal which is almost never the case), and the output volume is limited to -10db, and many recording aren’t providing a strong input signal, that just isn’t enough voltage leaving the SHD. It all starts with the 4V max output from the SHD and goes down from there. If the max ouput from the SHD started at something like 8V we wouldn’t be having this conversation because I could lose some voltage from the SHD and still hit my amp clipping. Right now it’s the other way around. Preventing the SHD from clipping is holding back my amp.

It’s unfair to say “you’ve got an amp problem” when I have an amp running a higher-than-average 28.6db of gain and that puts a healthy 185w/8ohms into a pair of LS50 Metas in a very small room... and it’s often just not loud enough at -10db on the SHD. That amp can blow a hole through the side of an LS50 with the right input voltage.
 

Ron Texas

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This piece of gear is important as it offers a balanced DAC, DSP and subwoofer integration in one box with a very good SINAD. Some members here have reported problems with firmware not initializing the unit reliably. Nobody in the US can fix it which means if something goes wrong, it's going to be a pain to get it fixed. Thank you @amirm .
 
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nothingman

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This is my understanding as well..the internal processing in the minidsp shd reduces the signal by 10db in order to apply boosts to dips. So you can still go up to 0db on the minidsp SHD, but that does not mean it is outputting a 4V signal over XLR/2V over RCA. I don't know if the minidsp does this, but as someone mentioned, it would have been good if the minidsp compensated for DIRAC by applying some gain.

Nope. No internal processing, no gain added. I wish that wasn’t the case.

From the SHD user manual: “Dirac Live can apply up to 10 dB of gain, so the output level should be kept lower than -10 dB to guarantee that there is no distortion with a full- scale input signal.”
 

Kachda

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This piece of gear is important as it offers a balanced DAC, DSP and subwoofer integration in one box with a very good SINAD. Some members here have reported problems with firmware not initializing the unit reliably. It's Chi-Fi which means if something goes wrong, it's going to be a pain to get it fixed. Thank you @amirm .
Deercreekaudio also sells this in the US https://deercreekaudio.com/products/minidsp-shd if you want to buy from a US based dealer.
 

Kachda

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Nope. No internal processing, no gain added. I wish that wasn’t the case.

From the SHD user manual: “Dirac Live can apply up to 10 dB of gain, so the output level should be kept lower than -10 dB to guarantee that there is no distortion with a full- scale input signal.”
Thanks..will keep this in mind. At least this confirms I am not the only one to think that the voltage out of the minidsp shd is too low with DIRAC enabled. I have a small apartment but in a large room I would definitely start hitting the voltage limits.
 

lobo

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If you just want to play with filters (no DIRAC) a raspberry pi + brutefir costs 50$. I'm running this combo to feed the filters made by flipflop (thanks!) to my topping dx7 pro and works great. Much more than 10 filters and taps!
 

Hayabusa

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Really happy with my SHD purchase so far (October 2020, so I guess I have the latest hardware). I have a few gripes like others but you can't argue with the level of audio performance, inputs, and DSP customization in this unit for $1200.

Tell me if I'm crazy, but the one thing that keeps cropping up for me is the 4V max output. Without Dirac, I don't think it's really a problem, but it becomes one with Dirac enabled which, per the manual, means you shouldn't bring the volume above -10db because you need to give Dirac that much room to guarantee it won't clip while boosting frequencies. -10db is more of a voltage drop than you might think, especially when your source signal is nowhere near approaching full strength.

I know this partly comes down to amp power and speaker sensitivity, but I'm using mainstream stuff here. Amp sensitivity is rated at 185w/8ohm @ 1.43v input (NAD C298), and JA's sensitivity measurement on the speaker is 84.5db (LS50 Meta).

So if the SHD would output more than 1.43 volts your amp would clip, so why is there a need to have more than 4 volt out?
 

Ron Texas

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Just wondering, the MiniDSP 2x4 HD is only $205 and offers similar functionality, or for $400 with Dirac. It measures much worse with a SINAD of around 90. Could I hear the difference. Perhaps someone young could.
 

nothingman

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So if the SHD would output more than 1.43 volts your amp would clip, so why is there a need to have more than 4 volt out?

Because 4V max at 0db input signal, minus whatever strength the input signal actually comes in at, minus 10db on the volume = way, way less than 1.43. It’s a precipitous drop.
 

nothingman

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Thanks..will keep this in mind. At least this confirms I am not the only one to think that the voltage out of the minidsp shd is too low with DIRAC enabled. I have a small apartment but in a large room I would definitely start hitting the voltage limits.

Glad (/not glad) to hear I’m not alone on this one. Was starting to think I’m taking crazy pills.
 

Hayabusa

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Because 4V max at 0db input signal, minus whatever strength the input signal actually comes in at, minus 10db on the volume = way, way less than 1.43. It’s a precipitous drop.
The SHD is floating point internal, it will ONLY clip if it outputs more than 4 volt.
 
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