Minidsp Flex Review (Audio DSP)

[Absolute]

i do not understand what is the difference between in and out. Excuse my ingnorance i have only made a manual room correction on one room and that was for roon which has an easy interface in this matter.

Flex is a 2 channel input and 4/8 channel output device. That means you have left channel input and right channel input.

You can use left (or right) input signal and send it to any number of output channels, for example Left input to left sub, left midbass and left tweeter, which would use 3 channels of output to the left active speaker.
Or in a more usual case - to left and right normal passive speakers with 2 or 4 channels left for subwoofers.

So that means any EQ done on the Left Input channel will work for the left speaker(s) only. We call EQ on the input channel for Global EQ because it gives the same EQ for all drivers/speakers assigned to that input channel.

Hope this makes sense.

 

[ehabheikal]

Flex is a 2 channel input and 4/8 channel output device. That means you have left channel input and right channel input.

You can use left (or right) input signal and send it to any number of output channels, for example Left input to left sub, left midbass and left tweeter, which would use 3 channels of output to the left active speaker.
Or in a more usual case - to left and right normal passive speakers with 2 or 4 channels left for subwoofers.

So that means any EQ done on the Left Input channel will work for the left speaker(s) only. We call EQ on the input channel for Global EQ because it gives the same EQ for all drivers/speakers assigned to that input channel.

Hope this makes sense.

This is a newbie question but what is the reason why doing crossover ( for my sub) be better than what the sub's crossover does?

 

[antcollinet]

This is a newbie question but what is the reason why doing crossover ( for my sub) be better than what the sub's crossover does?

Is your sub doing crossover, or just low pass filter

(IE is your sub highpassing the filter to send to your mains, or only doing low pass filter for output to the sub?)

 

[ehabheikal]

Is your sub doing crossover, or just low pass filter

(IE is your sub highpassing the filter to send to your mains, or only doing low pass filter for output to the sub?)

my sub is yamaha hs8s which is a studio sub it has high cut and low cut both 80 to 120hz

i set it for only high cut but i would not be able to justify why, i want the sub to take the sub base from my main speaker since my ls 50 meta is not very good at bass.

 

[ehabheikal]

my sub is yamaha hs8s which is a studio sub it has high cut and low cut both 80 to 120hz

i set it for only high cut but i would not be able to justify why, i want the sub to take the sub base from my main speaker since my ls 50 meta is not very good at bass.

my sub is yamaha hs8s which is a studio sub it has high cut and low cut both 80 to 120hz

i set it for only high cut but i would not be able to justify why, i want the sub to take the sub base from my main speaker since my ls 50 meta is not very good at bass.

This is the plate on my sub. Does this setting stop the bass from reaching my main speakers?

 

[antcollinet]

This is the plate on my sub. Does this setting stop the bass from reaching my main speakers?

Not unless the signal goes from source to sub then to amp and then to speakers. Which I think is not what is happening.

In this case, the speakers will still get the full range signal, and the sub will get the bass frequencies also - which is not ideal.

The mini dsp can implement a crossover, removing bass from the signal sent to your main speakers, and sending only the bass to your sub.

 

[ehabheikal]

Not unless the signal goes from source to sub then to amp and then to speakers. Which I think is not what is happening.

In this case, the speakers will still get the full range signal, and the sub will get the bass frequencies also - which is not ideal.

The mini dsp can implement a crossover, removing bass from the signal sent to your main speakers, and sending only the bass to your sub.

I am connected as you said, source to sub then to amp and speakers. So the image of my plate means the speakers still get the frequencies they should not?

 

[antcollinet]

I am connected as you said, source to sub then to amp and speakers. So the image of my plate means the speakers still get the frequencies they should not?

I can't tell from that picture.

Which sub? What source, what inputs from source to sub, what output from sub to amp?

 

[ehabheikal]

source soncoz sgd1 dac going via xlr to yamaha hs8s sub out to purify amp on xlr too.

i disabled low cut and set the high cut at the max of 120hz

 

[antcollinet]

source soncoz sgd1 dac going via xlr to yamaha hs8s sub out to purify amp on xlr too.

i disabled low cut and set the high cut at the max of 120hz

OK - you're correct, with that connect you can set both high pass (for the mains) and low pass (for the sub)

You need to enable both high cut and low cut.

High cut sets the top frequency for the sub. Low cut sets the minimum frequency for your mains. They should both be set to the same value. A starting point based on the Yamaha mid range would be 100Hz.

 

[ehabheikal]

OK - you're correct, with that connect you can set both high pass (for the mains) and low pass (for the sub)

You need to enable both high cut and low cut.

High cut sets the top frequency for the sub. Low cut sets the minimum frequency for your mains. They should both be set to the same value. A starting point based on the Yamaha mid range would be 100Hz.

View attachment 266860

You have been more than helpful thank you

 

[antcollinet]

You have been more than helpful thank you

Welcome.

 

[Sokel]

Yes,and severe one,specially noise.Multitones was also not good,at all.
All of that in the low's section,high's got a hit too but not as much.
The most odd one was TDH+N (SINAD) vs level.It was all over the place.

Fascinating, thanks for sharing.

I posted some digital measurements of a 2X4HD earlier in this thread -> https://www.audiosciencereview.com/...idsp-flex-review-audio-dsp.30804/post-1088121 and saw slight degradation in noise with a 80 Hz LR4 HPF but it wasn't that bad. Probably more interesting to try more complicated processing though.

When I get back to my audio stuff later this month I'll measure while applying the LXmini EQ and see what it looks like across a few different DSP platforms. It would be nice if we had some standard EQ profiles that we could apply as a consistent test across DSP platforms to compare degradation.

Michael

To whom it may concern @mdsimon2 stayed true to his word and kindly performed a true multi-test regarding the performance of devices like this and the difference when loaded with EQ profiles,DSP filters,etc.
The results for Sharc DSP based devises like this one is similar with the ones I measured and observed (as a newbie) and it was a relief I did not mislead anyone about it (I always afraid of this when I post my newbie measurements).

Audibility issues are unlikely to be,it remains to be tested with more complex filters but it's good to know that there are measurable issues at lows and not small ones.

EDIT:The test link:

DSP Measurements and Rising Noise Floor

In several threads related to DSP platforms I've seen requests for measurements with filters engaged. I thought it unlikely that implementing filters in a DSP would have measurable effect on noise / distortion other than the obvious change in the fundamental, however @Sokel recently mentioned...

www.audiosciencereview.com

 

[andymarks]

So about Dirac on the minidsp flex. The minidsp site says Dirac utilizes / opens up mixed phase filtering compared to REW using EQ and FIR. https://www.minidsp.com/applications/digital-room-correction/dirac-live-vs-rew#:~:text=The%20key%20differences%5BTop%5D,but%20more%20expensive%20to%20implement.
Can these mixed phase filters be manually adjusted after the Dirac measurement process?
Can these mixed phase filters be implemented manually without a Dirac license?
Or are the mixed phase filters just a combination of EQ and FIR filtering named differently by Dirac?

I also wonder is phase alignment useful in a tiny room?

I am currently using manual EQ in the box with REW. I have Kali IN-8's and 3 subs on concrete floor in a 3 meter by 2 meter well treated studio room. I doubt it is wise to mess with the phase between the Kali's and phase aligning subs seems to be something for the bigger rooms with more distance between subs. My subs are 1 meter away under the front and the sides desk. Maybe aligning the whole bunch with the speakers could improve the bass timing a bit.

In the near future I might put the two subs right under the Kali's with some decoupling in between so then phase is even more insignificant.

Anyway, if someone could shine some light on mixed phase filters vs regular EQ and FIR that would be nice.

 

[jesburger]

Are the TRS outputs on this mono or stereo?

 

[andymarks]

Balanced TRS is always mono, I assume you can link them as stereo pair in the configuration or decouple them as single mono outputs for subs. So you can output to two speakers and two subs or two series of subs if you daisy chain the signal.

I already found the answer to some of my questions. After the Dirac measurement process you can manually modify the settings of Dirac. This doesn't answer the question if these special Dirac filters are worth it compared to normal EQ and FIR but okay. I quess I'll download the manual again and see if I can find out more. I also found out that it would probably smooth out the crossover on my subs aswell as I currently use the low pass filters on them, but those aren't very steep filters, they leave a lot of mids through even when set at 50hz.

 

[antcollinet]

Are the TRS outputs on this mono or stereo?

They are mono - but still use 3 connections for the hot/cold/earth balanced signals. Do NOT plug a mono (TS) connector into the outputs.

 

[andymarks]

There's now also a 4th new flex with 8 unbalanced rca connections. I don't understand minidsp's focus on unbalanced connections seems to me they cater to an audiophile and music production world. So you gained a bit of flatter response, but now you have a bit of extra noise.

 

[andymarks]

There's now also an online manual for flex devices. Looking at the bit about FIR filtering it seems Dirac is just a user friendly automated route. The other route is to use REW EQ settings and import them into Rephase to calculate the FIR filters. Since the advanced crossover only supports biquad data I guess you would have to make the crossover yourself with FIR filters in order to get lineair phase similar to Dirac. Minidsp also have an article about Rephase here
Looks like you have to choose between pre-ringing and time delays or shifting phase by using regular filters and crossovers. In the end I might not be able to hear any difference

 

[anotherhobby]

They are mono - but still use 3 connections for the hot/cold/earth balanced signals. Do NOT plug a mono (TS) connector into the outputs.

Why do you say this, as miniDSP specifically documents the exact opposite?