[VinceT]

I came here to read up on active crossovers, I found GeorgeAb's recent thread regarding his pass DIY crossover

https://www.audiocircle.com/index.php?topic=186209.0

Not to muck up his thread, I decided to start my own being I have a few questions

First off, I can really see the positives for added external active crossovers and also the complexity the process adds. I have had experiences with the pro products like DBX driverack and Behringer products. I would never want them in my audio chain and agree the Pass or Marchand would be affordable alternatives.

But it appears tools like DBX driverack is used for the room measurement process to determine crossovers in your speakers when evaluating your desired crossover points and slopes. I would assume tools like room EQ wizard would be as valuable. I am have been wondering where I would find more info with that evaluation and measurement process for coverting speakers from passive to active crossovers?

Also it seems when going full active X over, depending on the slopes used am I safe to assume there will need to be some DSP involved to address the time and phase alignment and baffle compensation?

If that is the case, how would you incorporate a turntable back into the system?

Thanks in advance, VinceT

[TomS]

MiniDSP has pretty much everything you could want. I have the SHD, which only has 4 outputs, but also analog in for a TT. Many choices there. Their software works very well, easy to set up and a good learning environment.

https://www.minidsp.com/

Once you have everything prototyped and dialed in, you might be able to go with an analog xo such as the Sublime Acoustic or Marchand.
https://sublimeacoustic.com/

[VinceT]

Tnx TomS ...I forgot to add multi-channel dacs to the mix as well.

[TomS]

Aaahhh, that's a bit more complicated. Perhaps the DSPNexus products that HAL offers, though a bit more pricey.

[HAL]

This is the system that TomS is referring to:

https://www.danvillesignal.com/dspnexus-dsp-audio-processor

[VinceT]

Hal, been reading up on your threads as well

I like the price point of the DIY Pass/Marchand, but need to learn more about the implementation options

[HAL]

Here is one thing to consider if you are integrating subs into a multiway speaker system.

With DSP processing, you can use time delay on the mains to adjust the time alignment of the mains to the subs if they are in different places in the room.

A simple tape measure can be used to find the distance offset needed for the time delay correction at low frequencies. 

[VinceT]

Is some type of DSP mandatory?

[HAL]

It is by far the easiest way to do time delay for multi-channel crossover systems and has no sonic impact.

[VinceT]

I would say depending on the implementation and hardware, if there are internal dacs of these devices added to the chain they would impart something depending on the quality.

Looking at the DIY Pass/Marchand x overs, you could do the DSP in the source, and there are options there as well as far as hardware, software, mc dacs etc.

I would be curious comparing the  different implementations from others experience. Seems a lot of folks that go this route are going to great lengths to keep the external active crossovers as transparent and anaolog as possible.

Other question I had is what about the vinyl rig? Does that analog magic get affected with all the dsp added to the chain...as they say no free lunch in audio.

[richidoo]

Is some type of DSP mandatory?

No.

Rod Elliott
https://www.sound-au.com/articles/index.htm#cros
https://www.sound-au.com/p-cat.htm#xvr

The Design of Active Crossovers Book
https://a.co/d/9yG8iMN

Passive crossover is still king for sound quality and convenience but it's an artform and the true artists are rare now. A great passive xo requires excellent parts quality and that is very expensive.

Bass frequencies benefit most from active xo because the improved electrical damping of bass driver cone is more obvious and desireable than damping in mid/treble and active xo allows amp connected directly to driver voice coil. This is the main technical reason for active. The second most important technical advantage to active also requires DSP, that is linear phase filters, which is another level higher in complexity but not crucial to this discussion (until you hear it  )

DSP makes designing the filters easier than active analog design. But analog filters aren't that hard and offer two big advantages: infinite resolution and very low price. With the info linked above and $100 it is possible to have superior performance than any minimum phase DSP product. But no GUI, requires math and soldering so most will choose dsp, but not invest in multichannel high end electronics then give up because it sounds bad.

[GeorgeAb]

This is a post on the DIY Nelson Pass designed active crossover. May be of interest as there are inputs from a few folks who have different active xo.   

https://www.audiocircle.com/index.php?topic=186209.0

[HAL]

I would say depending on the implementation and hardware, if there are internal dacs of these devices added to the chain they would impart something depending on the quality.

Looking at the DIY Pass/Marchand x overs, you could do the DSP in the source, and there are options there as well as far as hardware, software, mc dacs etc.

I would be curious comparing the  different implementations from others experience. Seems a lot of folks that go this route are going to great lengths to keep the external active crossovers as transparent and anaolog as possible.

Other question I had is what about the vinyl rig? Does that analog magic get affected with all the dsp added to the chain...as they say no free lunch in audio.

The dspNexus 2x8 has balanced input RIAA phono capability with adjustable gain.  That is what I use now.

Good luck with your search.

[Jaytor]

Another option to consider is the Sublime Acoustics active crossover. This is a fully analog three way crossover with both RCA and XLR inputs and outputs. They have recently introduced a new model, the K235 which they are offering a preorder price of $900. I have been experimenting with the Danville dspNexus and have ordered a K235. The dspNexus provides more flexibility in tuning and particularly in time alignment, but replaces your streamer, DAC and preamp (which may be a good thing or not depending on what you are trying to achieve).

[andyr]

I would be curious comparing the different implementations from others experience. Seems a lot of folks that go this route are going to great lengths to keep the external active crossovers as transparent and analog as possible.

I started with active XOs for my 3-way Maggies 30 years ago - when there wasn't much else apart from 'analogue'.  I used Rod Elliott's P09 XO PCBs and bought the lspCAD simulation software, to be able to play with different slopes and XO points.

These worked very well - but about 8 years ago, I added a pair of 15" subs to my Maggies ... and these required delay to be implemented on the Maggies, to time-align them with the subs (which were situated about 5' further away from my ears).  Hence, I went to a miniDSP 10x10HD.

This was analogue in - and analogue out ... but because of this, it had to run at 48kHz.  By moving to digital in - I was able to increase the sampling rate to 96kHz.  So I put a 96kHz A2D converter after my phono stage ... and fed digital signals into the 10x10HD (my other sources were already digital).

Other question I had is what about the vinyl rig? Does that analog magic get affected with all the dsp added to the chain...as they say no free lunch in audio.

IME - no!   

But I have a good A2D converter (better than the one used in the miniDSP!).

[planet10]

Sublime Acoustics active crossover.

https://sublimeacoustic.com/

You have to live with LR 4th order filters.

dave

[Tyson]

Don't make the mistake I did and use the miniDSP.  It sounds terrible, really sucks the life out of the music.  If you want to use DSP and active crossovers, HAL's is the only thing I've heard that is at true audiophile level. 

[planet10]

There are a lot of models of miniDSP.

I have seen lots of differing reviews, enuff to question their QC.

I heard a cheap one, it was not great. A more expensive one more recently was fine.

I’d only buy one to use to work out where the best place and wha tthe best topology is for the speaker being developed.

I prefer the idea of analog XOs and a convolution filter for any needed EQ.

dave

[Tyson]

At the time I had the miniDSP it was their top of the line "HD" model.  Still crap.

[Speedskater]

It was the setting that were put into the miniDSP that were crap.