Digital Crossovers Software Hardware technical questions(Speaker Management Systems)

[Trdat]

I just can't get my head around a handful of issues around digital DSP speaker management systems. I have tossed up the option of multi channel DAC and using Audiolense for my digital crossover work and I sure many people here including the likes of DallasJustice will support this idea. But I am moving towards an affordable D/DSP and using Audiolense for the final correction which would correct in the time domain if the D/DSP doesn't work in the time domain that is(which most affordable ones don't). I don't always listen to music via Jriver not being able to have the convolusion on all times plus the ability to tweak sub actively and the fact that many affordable Chinese options with Sharc processors are available is pushing me to this direction.

I am keen to try two option one with the DSP in between the Preamp and the power amps and second one with my computer as the source and the DSP feeding into a few DACS and into their power amps.

If you could clarify, if the D/DSP has a digital input(in this case the computer directly into the DSP) does it bypass the internal conversions? I mean if I have a DAC after DSP how many A to D conversions are happening? And if the analogue leaves the DSP then enters the DAC what happens? I know MiniDSP has a Studio version which allows for this with a digital input but to spend 899 with only two outputs doesn't really give me option in future to have a 4 way system with full digital crossovers.

Secondly, if the computer is the source and the DSP only has a SPDIF or AES/EBU input how do I connect that? Do I need a USB to AES interface? Any advantage or disadvantages?

In general is one method significantly better than the other? If I purchase a top of the range speaker management system then I am inclined to trust its DAC and have my preamp before it which would make life easier. But prefer the idea of choosing my DAC after the DSP.

If anyone has DSP options for my above system please advise, and if they have been tested please chime in about how they work and and there quality and if I need my DAC or not. Anyone's help would be greatly appreciated. I am sure answers to these questions will untangle many issues for us starting in this field.

And if for some reason the Audiolense option is preferable let us know about that too so I can understand differences.

 

[RayDunzl]

Digital in/out DSP recalculates the values of the samples it receives and outputs the new samples. No analog involved.

Digital in/analog out DSP recalculates the values of the samples it receives and outputs the new samples to the internal DAC. No analog involved in the DSP part...

Analog in/analog out DSP digitizes the input, recalculates the values of the samples it created and outputs the new samples to the internal DAC.

---

I have digital in/out DSP devices. I consider them transparent except for the changes in the digit stream they are commanded to make.

Basically, Digital Sources -> DSP -> DAC -> Preamp -> Power Amp

 

[Hipper]

Sounds like the ideal solution would be something like a DEQX which has various digital and analogue inputs, ADC and DAC, DSP, crossover, and volume control.

https://www.deqx.com/products/hdp-5/

I realise it is expensive but you won't have loads of cables and boxes. Used may be available.

I don't know if there is something similar among the various miniDSP/Dirac boxes, Antimode gear or Lyngdorf.

Digital crossovers can be used for managing subs but are also used to replace the passive crossovers of multi way speakers so that you can create a digital crossover with more accuracy and drive the woofer, mid range and tweeter with separate amps.

The first thing you need to decide is what are your sources? What is the output terminal from them. This will decide what inputs you need for the next operation - probably a pre-amp.

DACs will have only digital in and analogue out. A box that includes an ADC (Analogue to Digital Converter) will have an analogue in too. So when choosing a box, you need to check its in and out terminals, both for the presence of an ADC and DAC, but also for the various types - Asynchronous USB (not just any USB as this could be only for downloading updates), balanced XLR, RCA, Toslink/optical. If you look at the picture of the back of the DEQX HDP-5 you'll see a complicated array of these.

This means that if you connect to a digital in of a DSP device and the signal comes out in digital there is no conversion. If you connect to an analogue in and an analogue signal comes out then the analogue signal will have been converted to digital by the ADC for the DSP (Digital Signal Processing) to take place, then the DAC will convert it back to analogue.

There are USB-SPDIF converters. Music Fidelity make one - the V-Link192.

I would think the general principle would be to keep the number of boxes and cables to a minimum.

There is also the logical signal path. Most people use DSP to correct for the room and speaker placement deficiencies so the same measurements would apply to all sources. Same goes for active crossovers. So the logical path is to have all sources as digital before the DSP and crossovers:

Sources>pre-amp with digital and analogue inputs>DSP>active crossover>DAC with multiple outs>amps>speakers

As mentioned, the DEQX HDP-5 covers 'pre-amp with digital and analogue inputs>DSP>active crossover>DAC with multiple outs' meaning all you need are sources, multiple amps (or a multi channel amp) and speakers.

This means the pre-amp has to have all the inputs you will use - USB, other digital, analogue, whatever.

That's my thoughts so far on a complicated subject.

 

[Trdat]

Digital in/out DSP recalculates the values of the samples it receives and outputs the new samples. No analog involved.

So if I find a DSP with a digital/in say a SPDIF or USB and a AES/EBU out to my Preamp/DAC there really isn't much conversion happening? And my preamp receives the digital source which is exactly what I am looking for.

---

I have digital in/out DSP devices. I consider them transparent except for the changes in the digit stream they are commanded to make.

Basically, Digital Sources -> DSP -> DAC -> Preamp -> Power Amp[/QUOTE]

Can you let me know some of your DSP devices with digital ins? Your chain is similar to which direction I am pointing to at the moment. Except that I will have a the Preamp to be a DAC after the DSP.

My source will only be computer into DSP with a USB or whatever it takes.

 

[Trdat]

Sounds like the ideal solution would be something like a DEQX which has various digital and analogue inputs, ADC and DAC, DSP, crossover, and volume control.

https://www.deqx.com/products/hdp-5/

I realise it is expensive but you won't have loads of cables and boxes. Used may be available.

I know a little about DEQX, but as it is expensive I have dissed it for other options because of this reason but I will look at second hand options, thanks for the idea. The rear does lay down the understanding of what inputs I need.

I don't know if there is something similar among the various miniDSP/Dirac boxes, Antimode gear or Lyngdorf.

I will also check out these other brands, miniDSP has but for 899 the two outputs is not enough for full digital crossovers in future.

Digital crossovers can be used for managing subs but are also used to replace the passive crossovers of multi way speakers so that you can create a digital crossover with more accuracy and drive the woofer, mid range and tweeter with separate amps.

This is my ultimate goal and working towards it. Just need to understand some of the concepts, which you have helped clear hopefully I'll get closer to the best option after this thread.

The first thing you need to decide is what are your sources? What is the output terminal from them. This will decide what inputs you need for the next operation - probably a pre-amp.

My source will only be computer and as it stands I only have a USB or HDMI output on my motherboard, and I am presuming HDMI is for Video so technically USB. USB>DSP

DACs will have only digital in and analogue out. A box that includes an ADC (Analogue to Digital Converter) will have an analogue in too. So when choosing a box, you need to check its in and out terminals, both for the presence of an ADC and DAC, but also for the various types - Asynchronous USB (not just any USB as this could be only for downloading updates), balanced XLR, RCA, Toslink/optical. If you look at the picture of the back of the DEQX HDP-5 you'll see a complicated array of these.

This complicated array of inputs and outputs is what I am looking for, unfortunately the market isn't providing anything like this for a reasonable price. I have found one DSP called Marani(one of those black box Chinese companies) which one model has a digital input a SPDIF with another model a AES/EBU. Would this work for what I suggested or for what your suggesting? Source>DSP with digital input(digital crossover)>DAC with digital input>Power amp?

This means that if you connect to a digital in of a DSP device and the signal comes out in digital there is no conversion. If you connect to an analogue in and an analogue signal comes out then the analogue signal will have been converted to digital by the ADC for the DSP (Digital Signal Processing) to take place, then the DAC will convert it back to analogue.

This paragraph just clarified with RayDunzl's answer as well what I needed to understand. So technically with a digital input on the DSP I can technically have my Preamp/DAC after the DSP. So to double check, this will work for digital crossovers and work all before the preamps? Just checking I know it will just double checking i understood everything correctly. Technically if croosed over at 150hz only the specified preamp will receive below 150hz with the other receiving over 150hz as a simplified example?

There are USB-SPDIF converters. Music Fidelity make one - the V-Link192.

This will set me back another $200 or so but I can also look for second hand. It seems this is the affordable option to choose a DSP with a AES/EBu or SPDIF input and use a converter.

I would think the general principle would be to keep the number of boxes and cables to a minimum.

Will try.


There is also the logical signal path. Most people use DSP to correct for the room and speaker placement deficiencies so the same measurements would apply to all sources. Same goes for active crossovers. So the logical path is to have all sources as digital before the DSP and crossovers:

Sources>pre-amp with digital and analogue inputs>DSP>active crossover>DAC with multiple outs>amps>speakers

This slightly differs from RayDunzl's chain, in which you have put the Preamp before the DSP? Any explanation or ads and disads this or that way? Unless this is chain is an example for an active crossover if I am not mistaken if so then yes this will have the preamp before the DSP and active crossover.

As mentioned, the DEQX HDP-5 covers 'pre-amp with digital and analogue inputs>DSP>active crossover>DAC with multiple outs' meaning all you need are sources, multiple amps (or a multi channel amp) and speakers.

This is a great option but i think a affordable PA DSP with a descent processor that has a digital input should do? If I have understood correctly. The DSP will cover digital input with digital crossovers for sub or for each speaker range in future and then into my preamp/DAC into my power amps.

This means the pre-amp has to have all the inputs you will use - USB, other digital, analogue, whatever.

Got this, yes my NADC510 has balanced input which will come from the DSP and has balanced outs which will go into my power amp.

That's my thoughts so far on a complicated subject.

Extremely complicated but you have pretty much narrowed things down for me, I really appreciate it. RayDunzl thanks as well!

 

[RayDunzl]

My source will only be computer into DSP with a USB or whatever it takes.

Do the DSP in the PC then.

Others can comment on how to go about doing that.

 

[Trdat]

Do the DSP in the PC then.

Others can comment on how to go about doing that.

I do have DSP on my comp. I am just tossing up the hardware DSP route. Plus I dont always play through Jriver hence won't have a convolusion on all times.

 

[Neddy]

Quite the rabbit hole, isn't it?
So don't mind the echoey sounds from down there in my reply:

With an analog chain, putting DSP in between - as noted above - adds 'yet another' A-D conversion.

Part of the reason I chose to use the Venu 360 is that it accepts AES inputs (in addition to analog), and now that the OktoDAC evidently provides AES outs for Ch's 1&2, I think it could be a major step up in sound quality for me.

I'm presently using the Venu for speaker crossover, sub integration, and room EQ (actually to implement results from REW, but can also use the Venu's mic/EQ system) , but am considering other (more robust) room EQ solutions (implemented, say, in JRiver) if I end up driving an OktoDAC from a PC.

Bottom line is that careful understanding of the various Gazinta and Gazouta technologies is a must - unless you just give up and go HDMI all the way...

 

[mitchco]

JRiver has a WDM driver, plus it has ASIO and WASAPI digital line inputs. This allows you to route your digital sources through JRiver's convolution engine. See https://wiki.jriver.com/index.php/WDM_Driver And https://yabb.jriver.com/interact/index.php?topic=77800.0
If your DAC has an ADC, then you can route analog sources (like a turntable) through JRiver's convolution engine.

I use JRiver for everything and with the digital line input options to JRiver's convolution engine (I use ASIO line in), I can route anything I want through the engine, all in the digital domain with no extra A/D conversions. I use Audiolense for a 3-way triamped system (2 way plus dual subs) using digital XO, time align the drivers, plus some frequency and excess phase correction. The Lynx Hilo I have has 6 analog outputs to run the stereo active three way, an ADC for analog input sources and Hilo supports coaxial (electrical) SPDIF connections on RCA jacks, or SPDIF Optical signals on TOSLINK connections.

The issue I have found in hardware DSP is the limited number of FIR filter taps. Typically limited to 6,000 taps, whereas on the PC you can run 65,536 or even 131,072 taps. If you want proper room correction below the rooms transition/Schroeder frequency, then one requires a lot of taps.

 

[Trdat]

Yes, very confusing.

So it seems I have a number of options

1. Choose a DSP hardware that accepts digital in. Advantage: Bypasses another A-D conversion Disadvantage: I need a USB to AES interface to connect to computer. Not a bad option overall I suppose it depends on the sonique performance of the DSP I choose and the according processing power.

2. DEQX Hipper is spot on, I can just connect with a synchronised USB and output to each DAC then power amp. I am yet to figure out if the HDP-4 can control up to 4 frequency ranges high, mid, low and sub and if it can be either from the the digital out and analog outs. This is a great option but severely expensive.

3. Software DSP This option I am familiar with I don't mind at all. Advantage: I already have Audiolense. Disadvantage: Need the convolusion on to reep the benefits. Also multi channel DAC are very expensive maybe a descent one is as expensive as the DEQX. I saw the Oktadac option affordable.

4. MiniDSP u-DIO8 This option isnt bad as I already have one descent DAC. Advantage: can implement my DAC and subsequent DACS as I go. Disadvatage: My NAD356 DAC module only accepts a USB so having a second DAC that I already own can't be utilised and need to purchase another DAC.


Question. Will different DAC's cause problems? The last three options work on the merit I have different DACS for each frequency range or does the software DSP correct issues with clock drift and timing?

 

[Trdat]

Hey Mitch,

I have purchased your E-book and have heavily follow your posts in computer audiophile forum and Audiolense forum. If I am not mistaken you are the one that advocates 4 subs with 2 sub taking the range of 100 to around 250hz placed at the back of the room to balance room modes. Anyway, I hope I got the right person lol all these pseudonyms.

So basically your recommending software DSP. My only problem here is the expensive nature of a multichannel DAC that's all really but if your advocating this direction then perhaps instead of wasting around 1k on the other options save and purchase a multichannel DAC.

I asked a question in the other reply, if I use different DACS with a USB to AES interface would that work? Why I ask is that I got a great DAC I want to use for the Sub frequency and possibly buy another DAC to hook up to my NAD356(NAD DACmodule only accepts USB).

Would Audiolense correct clock drift or timing issues with different DACS?

 

[pierre]

Yes, very confusing.

So it seems I have a number of options

1. Choose a DSP hardware that accepts digital in. Advantage: Bypasses another A-D conversion Disadvantage: I need a USB to AES interface to connect to computer. Not a bad option overall I suppose it depends on the sonique performance of the DSP I choose and the according processing power.

2. DEQX Hipper is spot on, I can just connect with a synchronised USB and output to each DAC then power amp. I am yet to figure out if the HDP-4 can control up to 4 frequency ranges high, mid, low and sub and if it can be either from the the digital out and analog outs. This is a great option but severely expensive.

3. Software DSP This option I am familiar with I don't mind at all. Advantage: I already have Audiolense. Disadvantage: Need the convolusion on to reep the benefits. Also multi channel DAC are very expensive maybe a descent one is as expensive as the DEQX. I saw the Oktadac option affordable.

4. MiniDSP u-DIO8 This option isnt bad as I already have one descent DAC. Advantage: can implement my DAC and subsequent DACS as I go. Disadvatage: My NAD356 DAC module only accepts a USB so having a second DAC that I already own can't be utilised and need to purchase another DAC.


Question. Will different DAC's cause problems? The last three options work on the merit I have different DACS for each frequency range or does the software DSP correct issues with clock drift and timing?

Multichannels DAC are not expensive: look at the ones from the pro world. From behringer to RME all the price spectrum is covered. All relative I guess Example 10 out channels for 550$ 108 dB dynamic range ...

 

[mitchco]

Hi @Trdat, thanks for purchasing my ebook. I believe it is @dallasjustice and his system here that you may be thinking of: https://www.audiosciencereview.com/...m2-audiolense-digital-crossovers-w-subs.2369/ I think Michael did use two DAC's but you would have to ask him. You would also have to ask Bernt at Audiolense wrt to clock drift or timing issues. I have not experimented with this scenario so can't say.

One 8 channel DAC with ADC, plus a multi-client ASIO driver is the Steinberg UR824 (under $1000) which seems to get a lot of love on the JRiver forum for folks with multichannel setups using convolution.

 

[Hipper]

Mitchco knows a lot more about using software solutions then I do.

What do you use when not using JRiver? Can it be run through JRiver?

One concern with using JRiver DSP is processing power of your PC. I've not yet used this in my audio PC so I've no idea how much it uses.

Your NAD C 510 pre-amp/DAC does not seem to have an ADC as it has no digital out.

So far then we have your PC with DSP leading to your DAC with analogue out. For crossovers you could get a box. You mentioned a Marina. They seem similar to Behringer products - made for pro-audio but still used by home listeners. Behringer make a DCX2496 digital crossover which has some EQ facilities. I've never used a DCX but my speaker manufacturer used it to design active crossovers for my speaker. He said he found the ADC and DAC of the DCX neutral in that he could hear changes to the earlier DAC in the system (your NAD in this case). The DCX has six outputs to amps, so it could be four amps for your two speakers and two for two subs for example.

A lot of people deride Behringer but I used a DEQ2496 as my equaliser and have had it for fifteen years or so with no problems.

So you would have: PC>NAD>Berhringer DCX>amps>speakers. All you'd need to buy is the Behringer and amps, or one multi channel amp plus cables.

Of course there may be other digital crossovers, perhaps with more outputs.

There remains the issue of your non JRiver source.

 

[Hipper]

This may interest you if you don't know it already:

https://www.audiosciencereview.com/forum/index.php?threads/minidsp-shd-dirac-live-rivals.7785/

 

[Krunok]

Would Audiolense correct clock drift or timing issues with different DACS?

Nothing would. Clock drift is not constant and cannot be corrected. The only solution is to either use a multichannel DAC which has a single clock or have a master clock for different DACs which is not aplicable for consumer grade DACs as they don't accept external clock.

Regarding cheap multichannel DACs you may want to have a look at this one.

 

[Willem]

Sorry if I have overlooked something, but it is still not quite clear to me what you are looking for: some dsp system to do crossovers between main speaker and subwoofers, a digital cross over between the drivers of your main speakers, or dsp room equalization.
If it is just for room eq with only a PC as a source, the easiest solution is to do this in software on the PC, e.g. by creating a correction graph in free REW software and apply this with the Equalizier APO free software. All this needs is a decent calibrated miscrophone like the Umik-1, and some time and software skills.
If you want to do room eq and use more sources than just a PC, you can use an Antimode 8033 to equalize where it matters most, i.e. just the subs. It is cheap, easy to use, and works well. If you want to equalize both your subs, and your main speakers, and optimize the crossover between them, the new Antimode X4 is an easy and excellent solution, but it is expensive (you get a DAC/preamp in the bargain). A minidsp DDRC-2D wil give you digital in digital out processing with Dirac room eq, but has no usb input. You can connect it between various digital sources (but not usb) and have a digital output to your existing DAC. It is quite affordable. The minidsp SHD wil also give you usb input but is more expensive.
Personally I would never ever apply a digital crossover to a speaker with an exisitng analogue crossover - it would make me into a substitute speaker designer and I fear the original designer is likely to be much better than I am.

 

[Trdat]

Ill take a look at the Steinberg thanks for the recommendation, it helps me get started with what I am looking for. I just spoke to Bernt, I won't copy his words as it is a personal email but I can summarise his comments. Basically he says all channels must be clocked at the same speed. And Audiolense cannot correct DAC clock speed.

Also, I appreciate you chiming in cause it looks like your reply will save me a lot of time and investment that would of gone in hardware DSP when know I can potentially just purchase a multi channel DAC and obviously separate power amps and new speakers.. The other responses also were very important in laying the ground work in understanding hardware DSP digital and analogue inputs outputs which is not something you can come across easily. I need to understand that anyway, on the off change I decide to go that route for other systems I might build.

 

[Trdat]

This may interest you if you don't know it already:

https://www.audiosciencereview.com/forum/index.php?threads/minidsp-shd-dirac-live-rivals.7785/

I will look into this.

 

[Trdat]

Nothing would. Clock drift is not constant and cannot be corrected. The only solution is to either use a multichannel DAC which has a single clock or have a master clock for different DACs which is not aplicable for consumer grade DACs as they don't accept external clock.

Regarding cheap multichannel DACs you may want to have a look at this one.

Krunok,

Thanks for your input, yes your correct about the clock speed thanks for that, important to know. Also, I looked into the minidsp not a bad option at all. Currently, my set up is pretty descent, I have an active crossover for sub duties. Marchand XM66 which has no reviews and nothing ever written or tested about so I am curious the effect it has on my overall system and the quality to price as I paid around $800 for the analogue variable crossover.

My point is, I needed to understand and untangle some of the concepts with Hardware DSP and with the thanks to the responses on this thread it seems the best option is software DSP. As, I am into DIY speakers it seems logical to DIY my own personal driver in a box and cross it over with digital crossovers.

Now the question is what works best a combination of passive components and digital crossover work done by Audiolense or is the ultimate goal pure digital crossover? And obviously need to find a descent multichannel DAC. I feel the cheaper ones might be a downgrade from my NAD356 or C510 as preamp.