Dac - Dsp - Crossover

[Al68]

Hi, I'm new to this forum and hope you forgive my mistakes.
I'm a old audiophile who wants to upgrade his (now) simple system (Oppo BD95 + Pass Labs amp + Magnepan MG 3.3) to multi amping. As everybody says Magnepans should sound better in multiamping (maybe all of the loudspeakers do) and I decided to try it.
After looking for a decent analogue crossover (Bryston 10B had "slight reduction in depth and a bit of an increase in electronic edginess " according to Stereophile, Marchands all have OpAmps, Pass XVR-1 is out of my budget, diy projects don't seem to work properly...) I moved my attention to digital crossovers.
My intention was to split the signal in 3 or 4 bands without extra ADC/DAC conversions, and I read your enthusiastic comments about OktoDac Pro.
Now the question is : since the OktoDac Pro is just a 8channels converter, what kind of digital crossover should I use to feed it? A standalone unit with 4 digital exits and 1 coax entry? Or should I look for a multichannel audio board for my computer which exits with 4 AES/EBU connectors? Or...what?
As you see I haven't got so much experience as "digital" audiophile...

 

[Pluto]

Marchands all have OpAmps…

So?

 

[Neddy]

Welcome !
More info on your source setup/options/preferences would help, but you have quite a few choices.

A) With the Oppo as a source, you could do the DSP/Xover thing downstream via something like the Venu360 https://dbxpro.com/en/products/driverack-venu360 which also accepts AES inputs (bypassing the ADC). (There are other similar devices, as well.)

Multi-channel AES output devices are problematic, but to do stereo AES (via toslink adaptor) from your Oppo would work. Also not technically 'state of the art' (see Venu360 test results elsewhere on ASR), but whether the difference from the Okto is audible? Less sure, but I've learned to crave the huge dynamic range it has.

B) Doing DSP/xover up stream of the Okto would also work well, though involves quite a bit more software/hardware. For an 'over the top, but supremely well documented example', see:
https://www.audiosciencereview.com/...oftware-crossover-and-multichannel-dac.12489/

I'm using a mix of both for my 7.1 channel setup - PC/JRiver -> OktoDAC8 -> Venu360 (AES) (bi-amped mains and subs), so am not doing any crossovers on the PC.

 

[Al68]

So?

Well... call me a purist.. but i don't esteem too much the sound coming out an OpAmp. Maybe I'm wrong but this is my humble opinion

 

[Kal Rubinson]

Well... call me a purist.. but i don't esteem too much the sound coming out an OpAmp. Maybe I'm wrong but this is my humble opinion

And I would have agreed.................................................25 years ago. As long as you maintain standards, it may now be better to be discerning rather than "purist."

 

[Al68]

Dbx Venu360... also accepts AES inputs (bypassing the ADC). (There are other similar devices, as well.)

So you mean that XLR inputs can be configured as analogue or digital by software? And XLR outputs? And is it the same for all of the digital crossovers, whatever brand?

 

[Kal Rubinson]

So you mean that XLR inputs can be configured as analogue or digital by software?

On this device, 2 of them: "(3) female XLRs (2 selectable between analog/AES digital audio formats)"

And XLR outputs?

Analog only.

And is it the same for all of the digital crossovers, whatever brand?

No.

 

[RayDunzl]

So you mean that XLR inputs can be configured as analogue or digital by software? And XLR outputs? And is it the same for all of the digital crossovers, whatever brand?

AES (S/PDIF for professional applications) uses XLR for its physical connectivity.

 

[andreasmaaan]

Well... call me a purist.. but i don't esteem too much the sound coming out an OpAmp. Maybe I'm wrong but this is my humble opinion

In general, good opamps offer better performance/lower distortion than discrete output stages. I don't know much about the architecture of the Oktodac Pro but, given its performance, I would guess that it uses opamps in its output stage, although I'm not sure.

But anyway, that's neither here nor there. If you're looking for a 6- or 8-channel DSP to use as a crossover feeding the Oktodac, you might consider the MiniDSP DDRC-88D. There's an application note that explains how it can be used for active loudspeaker crossovers. Since it comes with DIRAC, you could also use it for room correction/bass management if that's also possibly on the agenda.

You would need to feed it an AES/EBU input however. If your source is a computer, this would do the job, but there are alternatives out there.

 

[Pluto]

i don't esteem too much the sound coming out an OpAmp

I really don't see how you can make a broad generalization such as this. The finest studio equipment uses op-amps in abundance. Any analogue recording made in the last 20 years has been through dozens of op-amps before it gets to you, so forget about the ranting of self-appointed influencers and make your own judgement.

 

[RayDunzl]

Well... call me a purist.. but i don't esteem too much the sound coming out an OpAmp.

I have to ask...

Is it the configuration of circuit elements, the functionality, or that the typical opamp resides on an integrated circuit that causes your dismay?

 

[Pluto]

is it the configuration of circuit elements, the functionality, or that the typical opamp resides on an integrated circuit that causes your dismay?

Probably all of those things… everything except the actual sound

 

[Al68]

Probably all of those things… everything except the actual sound

Probably because not all the OpAmp were created equal... and often some very old models are used, or probably because I don't have so many opportunity to test dozens of dacs & amps like you have. You're lucky

 

[Al68]

Anyway I wanted to summarize some possible configurations about Xovers & multiamping. I realized this scheme to clarify pros & cons of some solutions.

 

[gene_stl]

I have a four way analog system using the Pioneer D23 which can usually be had for about $1000.
Two nights ago I had it on a test bench and the Distortion and noise from all eight outputs was 0.00x. I was amazed. Built in the mid seventies.

There is a similar crossover from Sony called the Esprit. Buy the Bryston you will love it. I heard it at Axpona 2019 and I thought it sounded great in a "mere three way" system. The kind of description from the stereophile article is utterly meaningless. With the control afforded by by an electronic crossover active system you can make a system sound however your mood suits you at any moment. (Edit: The Bryston 10B mentioned is a three way crossover from the mid nineties. What I heard at Axpona was a 2019 current system probably one of their T Rex systems.)

Go take a look at Tom Christiansen's Neurochrome website to get the straight dope on op amps and chips. You are laboring under many audiophille misconceptions. The late great Sigfried Linkwitz said of Neurochrome gear "I don't know how to measure such low distortion" or words to that effect.

I have heard some systems using the dbx drive rack (using Martin Logan electrostats and a sub) and the similar system from Behringer (using some monster cinema speakers) and they all sound great.

Because of local conditions I have picked up four Crown pro amps which have DSP on their inputs which can be used to implement crossover functions too. I think they are CDi 600 and one 1200 for the wooofers , but I haven't hooked them up yet. The have analog inputs but control of them is ethernet based. There are versions of the DSP that can take the music analog or digital. They are very high performance.

Unfortunately most audiophiles have to forget almost everything they think they know. You may have come to the right place if you are willing to learn.

Unfortunately for a multiway multiamp system, it is unlikely that anyone will bother to implement a method of switching between two systems let alone doing same in a blinded fashion. Instead of just level matching you would have to level match a three or four way system , in order to compare crossovers. My friend here in St. Louis who has the Behringer also has a couple of Marchands XM44. They look pretty good to me but you have to select your crossover frequency by module you can't change it quickly which you can do with DSP or with the Pioneer and Sony.

You also need to get over your aversion to op amps. They outperform discrete circuits everywhere. And this has been true (in audio) for at least thirty years. Since the the 741 and LM301 went obsolete, which was in the seventies.

nice diagram!

 

[Al68]

I have a four way analog system using the Pioneer D23 which can usually be had for about $1000.
Two nights ago I had it on a test bench and the Distortion and noise from all eight outputs was 0.00x. I was amazed. Built in the mid seventies.

There is a similar crossover from Sony called the Esprit. Buy the Bryston you will love it. I heard it at Axpona 2019 and I thought it sounded great in a "mere three way" system. The kind of description from the stereophile article is utterly meaningless. With the control afforded by by an electronic crossover active system you can make a system sound however your mood suits you at any moment.

Go take a look at Tom Christiansen's Neurochrome website to get the straight dope on op amps and chips. You are laboring under many audiophille misconceptions. The late great Sigfried Linkwitz said of Neurochrome gear "I don't know how to measure such low distortion" or words to that effect.

I have heard some systems using the dbx drive rack (using Martin Logan electrostats and a sub) and the similar system from Behringer (using some monster cinema speakers) and they all sound great.

Because of local conditions I have picked up four Crown pro amps which have DSP on their inputs which can be used to implement crossover functions too. I think they are CDi 600 and one 1200 for the wooofers , but I haven't hooked them up yet. The have analog inputs but control of them is ethernet based. There are versions of the DSP that can take the music analog or digital. They are very high performance.

Unfortunately most audiophiles have to forget almost everything they think they know. You may have come to the right place if you are willing to learn.

Unfortunately for a multiway multiamp system, it is unlikely that anyone will bother to implement a method of switching between two systems let alone doing same in a blinded fashion. Instead of just level matching you would have to level match a three or four way system , in order to compare crossovers. My friend here in St. Louis who has the Behringer also has a couple of Marchands XM44. They look pretty good to me but you have to select your crossover frequency by module you can't change it quickly which you can do with DSP or with the Pioneer and Sony.

You also need to get over your aversion to op amps. They outperform discrete circuits everywhere. And this has been true (in audio) for at least thirty years. Since the the 741 and LM301 went obsolete.

nice diagram!

Many Many thanks. You've been very informative. Honestly I'm approaching a completely new(for me) field in audio and i'm sure i'll learn a lot... more after realizing my first multiamp system. All of you have the experience i miss. I'm probably afraid of making my first mistake in this new field.

 

[gene_stl]

https://www.audiosciencereview.com/...oftware-crossover-and-multichannel-dac.12489/
There is a lot of great content in this thread and others by forum member "dualazmak" where you can improve your game.

https://www.audiosciencereview.com/forum/index.php?threads/humbly-presenting-my-diy.16590/
New member who went down the path you are considering and appears to have gotten it right.

 

[Al68]

https://www.audiosciencereview.com/...oftware-crossover-and-multichannel-dac.12489/
There is a lot of great content in this thread and others by forum member "dualazmak" where you can improve your game.

https://www.audiosciencereview.com/forum/index.php?threads/humbly-presenting-my-diy.16590/
New member who went down the path you are considering and appears to have gotten it right.

I'm learning so much from ASR and from the quoted discussions. But the first one focuses on software crossover and unfortunately i would need some more info on hardware active crossover. Any suggestion?

 

[gene_stl]

When I built my four way multi amp system I had a little claim that used repeat itself in my devious little mind. That was that with each amplifier only doing about two and a half octaves of the musical spectrum each, if I wanted to I could by four cheapo receivers that used SanKen hybrids (hybrid large chip power amps mounted on the heat sinks which were exemplary of lower priced receivers and integrated amps. I never saw a separate power amp that used them although Radio Shack or Lloyds might have been a place to look) and use them for power amps and if kept below clipping would STILL sound better than things with very expensive amps and cables. With multiple amps you also have multiple speaker cables which increases the gauge to the drivers.

What you need to do is get a crossover and some amps and go to work. You have not mentioned the speakers you have in mind. Are you building DIY or activating something you already have? How many ways are we talking about? Do you already have power amps? One of the sort of headachey things is that if you want to buy new stuff, there isn't much in low power available. (except (boo hiss) tube amps)

Parts Express has a very inexpensive DSP that can do a stereo four way system (DSP 408 iirc)
https://www.parts-express.com/Search.aspx?keyword=dsp 408&sitesearch=true
The next step up is probably a mini DSP system.
The dbx drive rack and Behringer would likely be similar (those are usually six channels so three way) You have to consider whether your amps can eat balanced or unbalanced and what the crossover has for in and out also. The pro gear is usually balanced , consumer gear unbalanced.

For just "trying things out" there are even four way car audio crossovers which probably have the same chipsets in them. You would need a 12-14 volt quiet power supply (you could use a storage battery as a capacitator) The low price of some of these things indicates how much margin there is in electronic gear. "Regular audio" probably owes car audio a debt of gratitude for causing the engineering of low voltage and high current circuitry since getting higher voltage in the mobile is a pia.

All these audio things are converging in quality and you probably could not distinguish between them in a decent blinded test. Regardless of what the golden eared reviewers claim. None of the companies that make the gear , also make the chips. Some of the biggest companies may have special ones made for themselves. (Crown DriveCore)

There is also china inc.
https://www.ebay.com/itm/NEW-Linkwi...729443?hash=item3b20490f63:g:J~kAAOSw6~VbzXzX

or one of these. nobody ever got fired for buying anything accuphase:
https://www.ebay.com/itm/ACCUPHASE-...352910?hash=item23d770db0e:g:66MAAOSwdxRewzjZ

The easiest way to orient yourself is just go to fleabay and find yourself a Pioneer D23 from Japan or somewhere else , even if you need to put a power transformer on its AC plug. Then you can play with crossover points , slopes and shelving (channel levels) . Very conveniently with knobs.
Then when you know what you like you can move to a DSP if you think that is worthwhile.

 

[Pluto]

I don't have so many opportunity to test dozens of dacs & amps like you have

Just to reassure you, I haven’t had the opportunity of testing dozens of different op-amps, but what I do know is that most of the widely-used modern(ish) devices offer a level of audio performance entirely satisfactory for anything you want to do in the field of crossovers, buffers, even possibly mic. amps (which, technologically, present a similar problem to moving coil pickup amplification).

The notion that op-amps, in general, have a “sound” unbecoming of audiophile objectives is palpable nonsense and, as I stated earlier, the chances are that any content not 100% digital has passed through, quite literally, dozens of such devices before arriving on its delivery format.