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Minidsp Flex Review (Audio DSP)

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RHO

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Hmm, I have the adapters MiniDSP provided for TRS -> RCA and on the TRS side and have red to center and bare (presumably white) to body/shield and the exact same configuration on the RCA side. There is no third connection so presumably the cold on the TRS is floating.
That is how I would do it too. Seems the most safe implementation.
 

RHO

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I have no idea how balanced audio works when connected with only the positive voltage of an unbalanced audio.

Like does it clip in this case at 2V or 4V?
2V. The 4V from a balanced connection is between hot and cold. Hot being +2V en cold being -2V, hence +2V - -2V = 4V.

Edit: Ignore me not reading the question right. It does not clip at 2V as @tonycollinet explains in post #884.
 
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dougi

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I have no idea how balanced audio works when connected with only the positive voltage of an unbalanced audio.

Like does it clip in this case at 2V or 4V?
The balanced input should be differential between the +ve and -ve. So if the balanced saturates and/or clips at 4V RMS, you can only get to 2V RMS single ended so there should be headroom. The best way to see is to set the input levels in the flex to 0dB and see what the meters are doing with a hot input. If no clipping then you are OK. If there is, the input attenuator will help clipping, but not overdriving the ADC.
 

tonycollinet

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I have no idea how balanced audio works when connected with only the positive voltage of an unbalanced audio.

Like does it clip in this case at 2V or 4V?
Probably not (Note -I don't know the input circuit of the flex, the following is based on my expectation of how it will work)

The balanced signal (say (+2V) - (-2V) 4V) will go into a differential amplifier which will turn that into a single signal to go into the ADC.

The ADC will be able to cope with a full scale balanced signal of up to 4V

When you connect an unbalanced signal (say (+2V) - (0V) = 2V), you will only be using half the input range of the ADC. You could in fact (most likely, but depending on the supply voltage for the input stage) go up to 4V unbalanced and not saturate the input.


An alternative arrangement might be (though I very much doubt it would work like this) for the hot and cold signals from the input being separately fed into an ADC with a 2V range, and the summing done digitally afterwards. In this case it would not be possible to increase the unbalanced input beyond 2V.
 

abdo123

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The balanced input should be differential between the +ve and -ve. So if the balanced saturates and/or clips at 4V RMS, you can only get to 2V RMS single ended so there should be headroom. The best way to see is to set the input levels in the flex to 0dB and see what the meters are doing with a hot input. If no clipping then you are OK. If there is, the input attenuator will help clipping, but not overdriving the ADC.

Thank you for sharing, glad to know.

when i said some of my records clip the Flex i meant the ADC gets Saturated. So in this case (someone with a balanced flex) the 6dB headroom is beneficial.
 

glc650

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I have looked at your post that you linked and I still cannot find a proper TRS to RCA adapter or cable. Does that mean I have to make one?
Doesn't minidsp sell them? I think when you order the flex there is even a drop down to buy some?
 

tonycollinet

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I have looked at your post that you linked and I still cannot find a proper TRS to RCA adapter or cable. Does that mean I have to make one?
Yeah - that is a bit of a problem. Most TRS to RCA are intended for stereo applications, not balanced. I've never actually seen one you can buy.

I made my own by cutting a standard RCA and soldering on TRS connectors.
 

BearWant

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Yeah - that is a bit of a problem. Most TRS to RCA are intended for stereo applications, not balanced. I've never actually seen one you can buy.

I made my own by cutting a standard RCA and soldering on TRS connectors.
I have tried to read all the prior conversations about this, but have only managed to confuse myself further. Sorry newbie here. This is my first post. Hi all! Does this only apply to the inputs. Or is there also controversy surrounding the use of the optional adapter cable from MiniDsp going from the Flex balanced output to RCA? If the latter is the case, has there been a cable solution identified from a vendor, or I am stuck trying to make a frankencable. I do not think I have faith in my ability to do this.

Anymore whisperings of that possible "hybrid" solution. I have one professional power amp which is balanced, but would also like to output to a vintage Pioneer unit.
 

tonycollinet

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You can use a TRS to RCA cable as described in miniDSP's guide to connect RCA Amplifiers to the Flex Balanced's TRS outputs: https://support.minidsp.com/support...ectivity-which-trs-to-rca-cable-should-i-use-

Using the same cable on the Flex Balanced's TRS inputs however is not recommended.
It'll work on inputs too. But Minidsp have measured a drop in Sinad when driving balanced inputs with unbalanced sources. It's not a big enough issue for most analogue sources.

But on inputs you can also use a TS to RCA connector which *is* readily available as a typical mono cable.

Simple wiring for both inputs and outputs.

Tip of TRS to pin of RCA
Sleeve of TRS to shield/ground of RCA.

MiniDSP's arrangement using a two core screened cable can provide some noise immunity in some circumstances, but is not necessary for basic functionality (I am using a simple single core screened wire)
 

BearWant

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Thank you both! This puts me at ease. I think I will be ordering the balanced Flex.
 
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Looks like they should be offering another configuration: 2 balanced outs + 2 unbalanced outs. That would solve a lot of problems because I think the major use case is 2 speakers + 1/2 subwoofers (which are often powered).
 

RHO

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?
What is wrong with just using the hot output to create an SE signal from the balanced outputs?
There's no reason to build one with 2 balanced and 2 SE outputs, because there already exists one: the one with the 4 balanced outputs.
 

MarcosCh

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What is wrong with just using the hot output to create an SE signal from the balanced outputs?
There's no reason to build one with 2 balanced and 2 SE outputs, because there already exists one: the one with the 4 balanced outputs.
Agreed, but i also feel the pain of the fellow members. Rca connectors are fool proof but tsr are not, and this thread is a testament of it. At least they could throw a couple of adaptors in the box, or a note "if in doubt, go to asr and ask tonycollinet"
 

tonycollinet

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Agreed, but i also feel the pain of the fellow members. Rca connectors are fool proof but tsr are not, and this thread is a testament of it. At least they could throw a couple of adaptors in the box, or a note "if in doubt, go to asr and ask tonycollinet"
To misquote Tom Hanks in Apollo 13

"It's not a miracle - I just went there"

:p
 

RHO

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Agreed, but i also feel the pain of the fellow members. Rca connectors are fool proof but tsr are not, and this thread is a testament of it. At least they could throw a couple of adaptors in the box, or a note "if in doubt, go to asr and ask tonycollinet"
Maybe some instructions in the owners manual could also help.
 

Dan B

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From the study you linked to:
  • There exists in this study no statistically significant evidence supporting the audibility of phase distortion in the musical samples provided, using the all-pass filter implementations chosen by the researchers.
Are you saying that you can hear a difference with music? If so this is an extraordinary claim that contradicts the study and it would be helpful if you could provide some evidence for this claim such as a level matched blind ABX test.
Check out this Audioholics review of what happened when they changed the crossover of a high end speaker to one using phase coherent FIR filters. Gene Dellasalla, the head of Audioholics, said he was skeptical that phase coherence based on papers he had read, but after listening to the difference as they switched back and forth he called FIR filters a "game changer", achieving "immediacy to the sound", "better imaging", and the "utmost accuracy and lifelike sound".

Ignore my opinion, watch the Audioholics 11:57 minute review here.

Do you think Gene Dellasalla was imagining things?

They used an expensive professional processor by Marani to do the FIR crossover filters, but the miniDSP Flex can do the same thing.
 

staticV3

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as they switched back and forth he called FIR filters a "game changer", achieving "immediacy to the sound", "better imaging", and the "utmost accuracy and lifelike sound".
Those impressions are worthless unless backed up by double-blind testing and his resulting confidence score. Yeah placebo is a real killjoy.
 
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