AlmaAtaKZ

Active Speakers Reference Thread

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Super Wammer
1 hour ago, MartinC said:

My apologies. You used the term 'meatgrinder'.

Yep, poor analogy.

If we consider that a DAC takes in discrete digital things and turns them into flowing analogue things, I'm sure we can all agree that "liquidiser" is far more appropriate.:)

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3 minutes ago, TheFlash said:

Yep, poor analogy.

If we consider that a DAC takes in discrete digital things and turns them into flowing analogue things, I'm sure we can all agree that "liquidiser" is far more appropriate.:)

Possibly the ADC stage was being referred to then...

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3 minutes ago, Tin said:

I also wrote it has great value for money and that I would recommend it over passive crossovers. It may be a poor analogy, but in a way it fits, don't you think?

After you original post, which is what I and others responded to. And you also posted an explanation for your 'meatgrinder' characterisation relating to bit resolution, which was also responded to.

The only point being that you objecting to 'missing a memo about miniDSP products being the absolute best' and that implying that no bad word about miniDSP products would be tolerated is ridiculous. All that was actually posted were totally reasonable comments in response to what you wrote.

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3 minutes ago, MartinC said:

After you original post, which is what I and others responded to. And you also posted an explanation for your 'meatgrinder' characterisation relating to bit resolution, which was also responded to.

The only point being that you objecting to 'missing a memo about miniDSP products being the absolute best' and that implying that no bad word about miniDSP products would be tolerated is ridiculous. All that was actually posted were totally reasonable comments in response to what you wrote.

Yes, but even after my original post, you kept on complaining that I said it was crap. The bit rate issues are real though.

See this article

The issue with the MiniDSP is its relatively low 93dB S/N. Even when you don't use it for digital volume control, when applying a XO, it has to lower the volume over a certain range until it can writes 0s. Also, when doing DSP functions you run into increasing noise, when lowering the volume at a certain frequency.

Additionaly you get rounding errors coming out of Fourier space.

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I'm not looking to pointlessly drag out a discussion so I'll just respond to this part:

5 minutes ago, Tin said:

The issue with the MiniDSP is its relatively low 93dB S/N.

It is not 'the' miniDSP, rather miniDSP is a brand with a significant number of products. I'm not sure which one you've found that SNR for but they vary. 

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Super Wammer
12 minutes ago, Tin said:

Yes, but even after my original post, you kept on complaining that I said it was crap. The bit rate issues are real though.

See this article

The issue with the MiniDSP is its relatively low 93dB S/N. Even when you don't use it for digital volume control, when applying a XO, it has to lower the volume over a certain range until it can writes 0s. Also, when doing DSP functions you run into increasing noise, when lowering the volume at a certain frequency.

Additionaly you get rounding errors coming out of Fourier space.

Have you heard one? Compared with what?

Your theory is impeccable but whether folk can hear any difference, and whether they consider any audible difference to be positive or negative is up for discussion.

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4 minutes ago, TheFlash said:

Have you heard one? Compared with what?

Your theory is impeccable but whether folk can hear any difference, and whether they consider any audible difference to be positive or negative is up for discussion.

I have heard one. I like my analogue active crossovers better.

It took Linn at least 4 years before their digital crossovers were improving over the older analogue ones.

With my DSM and its upgrade to the AKM DAC, I -think- that my setup gets pretty close to what Exakt could offer up to 2 years ago, although I haven't heard that comparison with quite similar speakers. So I might be a bit off in that respect.

And as I wrote earlier; before its upgrade my streamer suffered from the same issues with its digital volume control.

The issue -was- audible, even as it actually had analogue attentuators to compensate for the problem up to 24dB.

Edited by Tin

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12 hours ago, Tin said:

Yes, but even after my original post, you kept on complaining that I said it was crap. The bit rate issues are real though.

See this article

The issue with the MiniDSP is its relatively low 93dB S/N. Even when you don't use it for digital volume control, when applying a XO, it has to lower the volume over a certain range until it can writes 0s. Also, when doing DSP functions you run into increasing noise, when lowering the volume at a certain frequency.

Additionaly you get rounding errors coming out of Fourier space.

Hi,

The miniDSP products use 24bit ADC/DAC, and 32bit processors with 40bit ALU, using floating point arithmetic.

The issue you refer to for the reduced S/N does not exist, as the article linked is based on 16bit values, which has the reduced S/N if attenuated in the digital domain. Most recordings do not use the full 16bits which compounds the issue.

The miniDSP if using the A/D function, will require the user to ensure that the maximum output voltage is used, 2.1Volts RMS.

If you use the TOSLINK input, then this will include the relevant codes for subsequent determination for data width, sample rate etc., but should be evident from the optical receiver internal memory. The logic within the miniDSP unit will ensure that the 16bit values are shifted to fill the 24bit word at least, such that the digital volume control provides the maximum S/N whilst attenuating the signal.

The volume control will be applied before the crossover, where the individual driver volume adjustment is after the crossover. The DSP uses floating point, so accuracy and dynamic range are not an issue for the application.

The crossover is implemented using simple 4th or 8th order filters, which are 4 and 8 taps respectively. The system will not convert the data into the frequency domain, for such a simple function, which negates any possible rounding errors.

Regards,

Shadders.

Edited by Shadders
Clarity.

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Super Wammer

I tried an early miniDSP 4 way digital crossover some years ago, using the analogue inputs, and found that it significantly degraded the sound, even when everything was set to flat and pass through. Even at the time people were singing their praises but this simple test proved they weren't very good back then.

That was probably 4 years ago and I'm pretty sure they will have improved enormously since then.  So when someone tried a miniDSP product could have a very significant bearing on their opinion. Same with Exakt, for the first 2 years it just wasn't very good, but now is rather excellent - I've spoken to some speaker designers who heard the early iterations and still dismiss it out of hand without trying it again.

Same issue over and over again. My favourite is "I'll not bother with listening to that because I don't like the Linn sound".  "Which one?" "When I heard it 20 years ago". Hmmm

Edited by sunbeamgls
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Super Wammer
6 minutes ago, Shadders said:

Hi,

The miniDSP products use 24bit ADC/DAC, and 32bit processors with 40bit ALU, using floating point arithmetic.

The issue you refer to for the reduced S/N does not exist, as the article linked is based on 16bit values, which has the reduced S/N if attenuated in the digital domain. Most recordings do not use the full 16bits which compounds the issue.

The miniDSP if using the A/D function, will require the user to ensure that the maximum output voltage is used, 2.1Volts RMS.

If you use the TOSLINK input, then this will include the relevant codes for subsequent determination for data width, sample rate etc., but should be evident from the optical receiver internal memory. The logic within the miniDSP unit will ensure that the 16bit values are shifted to fill the 24bit word at least, such that the digital volume control provides the maximum S/N whilst attenuating the signal.

The volume control will be applied before the crossover, as will any individual volume adjustment. The DSP uses floating point, so accuracy and dynamic range are not an issue for the application.

The crossover is implemented using simple 4th or 8th order filters, which are 4 and 8 taps respectively. The system will not convert the data into the frequency domain, for such a simple function, which negates any possible rounding errors.

Regards,

Shadders.

Is there only one DAC in a miniDSP digital crossover, or perhaps one per channel?  Is there an FPGA or similar doing the work and then passing along to a DAC or is the DAC doing everything?

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3 minutes ago, sunbeamgls said:

Is there only one DAC in a miniDSP digital crossover, or perhaps one per channel?  Is there an FPGA or similar doing the work and then passing along to a DAC or is the DAC doing everything?

Hi,

Depending on the product, multiple DACs are used, and the DSP implements the crossover. A crossover is such a simple calculation, that the DSP memory will suffice, and no external memory will be required.

Regards,

Shadders.

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