DSP Crossovers

[Aadams]

Anybody here done anything with multiway DSP crossovers?  BTW before you say "no",  experience is not required in this thread just thinking about it is creditable.

Adams

[Guido57]

I've been considering it.  Somewhere, I believe on AK, one builder was planning on using one to get some new speakers ready for a meeting then building a more traditional crossover later.  His concern with using a DSP was possible effects from the analog to digital back to analog conversions while the traditional crossover keeps everything analog.  As the DSP is programmable it may be a viable prototyping option but many prefer to limit analog<>digital conversions.

[Aadams]

50 minutes ago, Guido57 said:

I've been considering it

I was beginning to hear crickets. 

It had not occurred to me that someone would use an analog source with a DSP.  I was thinking entirely digital until just before the amps.

[Guido57]

https://audiokarma.org/forums/index.php?threads/new-build-for-shootout-in-las-cruces.852428/reply&amp;quote=12350123

On point of interest in a DSP with an analog source is having a programmable crossover for prototyping, another is that doesn't involve physically building one.  The miniDSP  https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4     actually looks like this is one of it's features. They're also available at a cheaper price than analog active crossovers.  The top link is to a builder on AK.

[RTally]

On 3/12/2019 at 8:16 AM, Aadams said:

I was beginning to hear crickets. 

It had not occurred to me that someone would use an analog source with a DSP.  I was thinking entirely digital until just before the amps.

An external DSP used as a crossover is going to be inserted between the preamp and the amps. It has to be done this way because there is a single input and at least two outputs from the DSP crossover. Putting the DSP crossover before the preamp means there will be multiple preamps that will have to be level matched every time the volume is adjusted. Unless your preamp has a digital output, the DSP will have to have an analog input. The only way I can imagine a digital input without needing multiple preamps is if you were using a PC as a preamp. But I cannot imagine using a PC as a preamp in a system that is biamped.

[Aadams]

 Yes “ before the amps” means before the Amps that power the hi mid low sub speaker units. I had not thought that someone would start with vinyl and do AD then DA. Seems to go against the unwritten code of the vinylphiles.  I see the appeal of prototyping.

[Aadams]

19 hours ago, RTally said:

The only way I can imagine a digital input without needing multiple preamps is if you were using a PC as a preamp. But I cannot imagine using a PC as a preamp in a system that is biamped.

I was thinking digital until the speaker amps.  For example, the 2x8 miniDSP product can allow for SPDIF, Toslink, USB, balanced and unbalanced stereo analog in to the DSP.  Apparently any AD conversion and all channel equalization , crossover filtering and final DA conversion is done inside the DSP before output to the power amps.  You use a computer software application to set the run profile of the DSP.  It allows the user to describe the DAC, preamp, crossover and equalization that is desired for 2 channels in and up to 8 channels out to power speakers.   Once your "preamp" is profiled you don't touch the software in normal use. 

You could then turn on your pc or digital music player of choice and go completely digital until just before the power amps,  with nothing except wiring between the power amps and speaker drivers.

[RTally]

On 3/14/2019 at 9:56 AM, Aadams said:

I was thinking digital until the speaker amps.  For example, the 2x8 miniDSP product can allow for SPDIF, Toslink, USB, balanced and unbalanced stereo analog in to the DSP.  Apparently any AD conversion and all channel equalization , crossover filtering and final DA conversion is done inside the DSP before output to the power amps.  You use a computer software application to set the run profile of the DSP.  It allows the user to describe the DAC, preamp, crossover and equalization that is desired for 2 channels in and up to 8 channels out to power speakers.   Once your "preamp" is profiled you don't touch the software in normal use. 

You could then turn on your pc or digital music player of choice and go completely digital until just before the power amps,  with nothing except wiring between the power amps and speaker drivers.

From what info is available on the miniDSP page, the miniDSP has an option to include the preamp control functions in the digital domain. Without the optional volume control, you will need a preamp to adjust listening volume.

It seems that the miniDSP is a device that is tailored to what you want. 

As for nothing except wiring being between the source and the amp, don't forget that the miniDSP has an analog circuit connected to the output of the DAC chip. The design and build quality of that analog circuit has a BIG impact on the ultimate SQ from the system. That is one reason there is such disparity in sound quality between different DAC units.

[Aadams]

On 3/15/2019 at 1:33 PM, RTally said:

It seems that the miniDSP is a device that is tailored to what you want. 

One thing that I have noticed about all these DSP products is zero provision for convenient L/R balance control in stereo applications.  IMO this means you must have preamp.  It is not problem, just another box that cannot be absent if you are playing 2 channels out.