converting revel f208 to active crossover with 6 amps

[JPA]

Thanks for the insight, from what I understand if you have 2 setups with the same crossover points and slopes, one done with DSP and the other done passively, the one done via DSP will have lower distortion, more uniform phase response, and lower resistance

Would you say this is accurate?

You may want to read these articles:
https://sound-au.com/biamp-vs-passive.htm
https://sound-au.com/bi-amp.htm

 

[NJ coffee roaster]

You may want to read these articles:
https://sound-au.com/biamp-vs-passive.htm
https://sound-au.com/bi-amp.htm

I have either seen these or something very similar, but what I am proposing is different, as the passive crossover elements would be completely eliminated all around.

 

[DVDdoug]

I suspect you'll be happy with results! And you have more ability to tweak the sound. Even if you don't make a technical-measurable improvement or a significant effect, you'll have "DIY bias" or The Ikea Effect". That's assuming you don't badly foul-up something...

But I wouldn't do anything irreversible because that will take-away value and make them harder to use if they ever get passed-on to someone else.

 

[dualazmak]

Already have 4 mono amps, considering grabbing 2 more (probably topping b100s) and swapping minidsp flex for htx to use the htx as an active crossover, one amp per driver, totally bypassing the f208 internal crossover. Curious how much improvement I could expect if I do this.

It looks you are going into quite a similar exploration mountain-climbing journey which I have been experiencing during 2020 throughout 2025.
Welcome to our world of PC-DSP-based multichannel multi-amplifier multi-SP-driver full-active stereo audio system!

My multichannel project thread is here;
Multi-Channel, Multi-Amplifier Audio System Using Software Crossover and Multichannel-DAC
and you can find the Hyperlink Index for my above thread here and here.
The details of my latest total system setup can be found here #931 and #1,009 on my project thread.

I believe you would understand (and learn) almost all the major merits (pros) of our such set up as well as the important safety features to be implemented in our multichannel multi-SP-driver multi-amplifier audio setup when you would carefully read the lengthy posts #931 and #1,009.

I do hope much success (and pleasure) during your coming DIY exploration, and finally you would fully enjoy music with your completed multi-channel multi-amplifier audio setup.

 

[dfuller]

The greatest improvement will come from using brick-wall, FIR filters. This will give the following benefits:

• Total elimination of any lobing due to the crossover and smooth out any XO related frequency response anomalies

• Require around 50% less power (maybe even less) to reach the same output level since passive crossovers waste 3-6dB of power as heat dissipation

• Totally eliminate the danger of amp clipping burning out a tweeter or mid. You can also run a limiter on each driver to make sure they don’t get too much power.

• Allow you to perfectly time align the drivers

• Reduce amplifier IMD since the frequency range each amp covers is much smaller

• Increase the maximum output of the loudspeakers by around 3dB

• Running a high-pass filter just below the port tuning frequency will help protect the woofers from bottoming out if sub-bass hits the speaker (a problem with any ported design). This will save power and reduce distortion a bit when you’re playing loud music.

There are 3 things to consider:

• You’re going to need to do a lot of research on your end and invest in a measurement microphone & software to get the absolute most out of this type of rig. It’s not going to be easy.

• Your source is now going to be your computer if it’s not already

• This is not going to be inexpensive if you’re going to do it right. Don’t cheap out on anything.

You may also want to get Dirac Live into the equation since MiniDSP supports it. And, oh, yeah, use the Revel crossover points.

When you have this entire process done, your audio system will sound as good as it can with those speakers.

Having done this myself, the end result is definitely better than the passive crossovers, but it’s certainly not a night and day improvement since you’ve only improved 20% (at best) of the speakers characteristics.

Oh my god, no. Do not use brick wall filters, they ring like crazy, and at typical crossover frequencies that ringing is audible as hell. Worse still it's FIR (which I read as linear phase).

Also - insertion loss is at worst 3dB. It would have to be spectacularly bad to burn 6dB of level.

 

[dualazmak]

BTW, we have similar recent discussion thread;
Upgrading loudspeakers to digital crossovers/bi/triamping
where I partly participated based on my actual experiences.

 

[dualazmak]

I suppose I am more asking if anyone here thinks that keeping the same crossover slopes and points as the stock passive ones but done in the dsp with individual amps will yield a benefit vs the passive ones.

Yes, I am here for you!
I have started the DSP evaluation by simply "simulate" the excellent passive LCR-network of 3-way SP system, YAMAHA NS-1000 (not NS-1000M).

And even after various evaluation of DSP parameters (XO/Slopes/Group-Delay/Time-alignment/slight-EQ/Phae/Gain, etc.), the DSP/XO configuration in my present completed system is still very much similar to the YAMAHA's original passive ones in that heavy-rigid SP cabinet; of course, the "total sound quality" has been amazingly improved not only in the sealed 3-way active SP system (woofer, midrange, tweeter are directly driven by each of the dedicated amplifiers) but also with heavy-large-rigid L&R subwoofers (YANAHA YST-SW1000, 49 kg) and L&R super-tweeters FOSTEX T925A in wide-3D reflective-dispersion configuration.

Recently I wrote here;
"Complete elimination of passive LCR (inductors + capacitors + resistors + attenuators) crossover network (which convert considerable portions of SP-high-level signal into wasting heat!) is one of the major preferrable factors."


In any way, I highly recommend you would firstly start evaluation of DSP-XO configuration which would almost simulating the original passive CLR-network of your specific SP system.

Furthermore, if possible, you may better to preserve the passive LCR-network hopefully in outer box (as your reference sound system) to which you may easily role back from time to time during your exploration journey, as I recently wrote here.

 

[dualazmak]

I hope the four five diagrams under the below spoiler cover would help your at-a-glance understandings on what I mean...
(One diagram/photo would worth more than 1,000 words, I believe.)

Spoiler

For the details, please visit #931...

 

[Chrispy]

Yes, I am here for you!
I have started the DSP evaluation by simply "simulate" the excellent passive LCR-network of 3-way SP system, YAMAHA NS-1000 (not NS-1000M).

And even after various evaluation of DSP parameters (XO/Slopes/Group-Delay/Time-alignment/slight-EQ/Phae/Gain, etc.), the DSP/XO configuration in my present completed system is still very much similar to the YAMAHA's original passive ones in that heavy-rigid SP cabinet; of course, the "total sound quality" has been amazingly improved not only in the sealed 3-way active SP system (woofer, midrange, tweeter are directly driven by each of the dedicated amplifiers) but also with heavy-large-rigid L&R subwoofers (YANAHA YST-SW1000, 49 kg) and L&R super-tweeters FOSTEX T925A in wide-3D reflective-dispersion configuration.

Recently I wrote here;
"Complete elimination of passive LCR (inductors + capacitors + resistors + attenuators) crossover network (which convert considerable portions of SP-high-level signal into wasting heat!) is one of the major preferrable factors."


In any way, I highly recommend you would firstly start evaluation of DSP-XO configuration which would almost simulating the original passive CLR-network of your specific SP system.

Furthermore, if possible, you may better to preserve the passive LCR-network hopefully in outer box (as your reference sound system) to which you may easily role back from time to time during your exploration journey, as I recently wrote here.

He hasn't even done the sub thing yet....

 

[dualazmak]

He hasn't even done the sub thing yet....

Yes, I know and agree.
I believe, however, even without subwoofers, OP @NJ coffee roaster can easily find/hear the pros of active multi-amplifier DSP setup...

And furthermore, I would like to recommend him possible implementation of L&R subwoofers capable of going down to around 16 Hz...(typical ref. here #782).

 

[Chrispy]

Yes, I know and agree.
I believe, however, even without subwoofers, OP @NJ coffee roaster can easily find/hear the pros of active multi-amplifier DSP setup...

And furthermore, I would like to recommend him possible implementation of L&R subwoofers capable of going down to around 16 Hz...(typical ref. here #782).

Meh, whether all that work/expense is worth it is pretty subjective.

 

[NJ coffee roaster]

It looks you are going into quite a similar exploration mount-climbing journey which I have went through during 2020 throughout 2025.
Welcome to our world of PC-DSP-based multichannel multi-amplifier multi-SP-driver full-active stereo audio system!

My multichannel project thread is here;
Multi-Channel, Multi-Amplifier Audio System Using Software Crossover and Multichannel-DAC
and you can find the Hyperlink Index for my above thread here and here.
The details of my latest total system setup can be found here #931 and #1,009 on my project thread.

I believe you would understand (and learn) almost all the major merits (pros) of our such set up as well as the important safety features to be implemented in our multichannel multi-SP-driver multi-amplifier audio setup when you would carefully read the lengthy posts #931 and #1,009.

I do hope much success (and pleasure) during your coming DIY exploration, and finally you would fully enjoy music with your completed multi-channel multi-amplifier audio setup.

I have never seen anything like that super tweeter setup before, truly fascinating!

 

[Chrispy]

I have never seen anything like that super tweeter setup before, truly fascinating!

Now this is a super tweeter setup

 

[dualazmak]

I am very much interested in possible comparison of such multiple-super-tweeter in multi-directional configuration (your above photo) with my single-super-tweeter in wide-3D-reflective-dispersion configuration using random-face hard-heavy-glass material (ref. #931)!

 

[skankhobag]

Oh my god, no. Do not use brick wall filters, they ring like crazy, and at typical crossover frequencies that ringing is audible as hell. Worse still it's FIR (which I read as linear phase).

Also - insertion loss is at worst 3dB. It would have to be spectacularly bad to burn 6dB of level.

Interesting that Lake, Meyer Sound, Marani, Four Audio and Electro-voice are some of the pro audio companies making FIR processors. Then you have MiniDSP, DEQX, Legacy and Colinear offering hi-fi FIR processors. Hypex even makes plate amps that can run FIR filters. Also, it seems like any decent active speaker being introduced uses some form of FIR processing.

So, yeah, I guess the slow, but steady proliferation of FIR processing in audio as CPU power becomes cheap is because linear phase filters really suck.

Makes perfect sense.

 

[dualazmak]

As I repeatedly pointed on several threads within ASR Forum, one of the great merits/pros of this multichannel multi-amplifier approach is that we can choose/select amplifiers in the policy of "right-person-in-right-place". To drive our tweeters and super-tweeters, we do not need powerful amplifier, but we need small-power high-S/N low-distortion amplifier for each of them.

For example, even Greg Timbers uses "reasonable and budget" Pioneer Elite A-20 for compression drivers (super tweeters) in his extraordinary expensive multichannel stereo system with JBL Everest DD67000 which he himself designed and developed (ref. #435).

Furthermore, for relative gain control/tuning among multiple SP drivers, we can fully optimize not only in digital domain by DSP, but also we can safely and flexibly (even on-the-fly i.e. while listening to music!) control them in analog domain using preamplifiers (DAC-unit integrated, line-level-preamplifier, and/or integrated-amplifier).

In my post #931 on my project thread, I wrote as follows under the below spoiler cover.

Spoiler

Here in this post, please let me emphasize again about the pros and merits of relative gain (i.e. tone) control not only in digital domain but also in analog domain using pre-amplifiers or integrated-amplifiers (in my setup). I recently wrote again in my post #56 on a remote thread like these;
Yes, as for safe and flexible tone controls (or I can say "relative gain controls among the multiple SP drivers"), my stance (policy) at least, is that we are encouraged to utilize the "best combination" of "DSP configuration in digital domain" and "analog domain tone controls using HiFi-grade preamplifiers and/or integrated amplifiers".

We need to note (and to respect for) that analog domain tone controls (relative gain controls among the multiple SP drivers) give no effect nor influence at all on the upstream DSP configuration (XO/EQ/Gain/Phase/Polarity/Group-Delay). I believe that this is a great merit of flexible tone controls in analog domain. We know well, on the other hand, in case if we would like to do the "tone/gain controls" only within DSP configurations, such DSP gain controls always affect more-or-less on "XO" "EQ" "phase" and "delay" of the DSP settings which will leads you to possible endless DSP tuning spirals every time; within DSP configurations, XO EQ Gain Phase and Delay are always not independent with each other, but they are always interdependent/on-interaction.

Just for your possible reference, my DSP-based multichannel multi-SP-driver multi-amplifier active system has flexible and safe analog level on-the-fly relative gain controls (in addition to upstream on-the-fly DSP gain controls) for L&R subwoofers, woofers, midrange-squawkers, tweeters, and super-tweeters, all independently and remotely. My post here shows you a typical example case for such safe and flexible on-the-fly analog-level tone controls. This my post (as well as this post) would be also of your interest.

Of course, I know well that I (we) can also perform such relative gain control using DAC8PRO’s 8-channel output gain controllers. I do not like, however, to change the DAC8PRO’s output levels frequently on-the-fly (while listening to music) due to safety and inconvenience concerns; I like to keep DAC8PRO’s analog out gain level always at constant -4 dB which should remain to be usually “untouchable” in my case.

One of the very unique aspects/features of my multichannel audio rig is that I fully utilize four HiFi-grade “integrated amplifiers” plus L&R active subwoofers, each of them have its own gain (volume) controller for safe and flexible relative gain (tone) control in analog domain even on-the-fly i.e. while listening to music.

In this perspective, my posts #438 and #643 should also give you better understandings. Furthermore, my posts #317(remote thread), #313(remote thread) would be also of your reference and interest.

 

[YSDR]

The greatest improvement will come from using brick-wall, FIR filters. This will give the following benefits:

• Total elimination of any lobing due to the crossover and smooth out any XO related frequency response anomalies

• Require around 50% less power (maybe even less) to reach the same output level since passive crossovers waste 3-6dB of power as heat dissipation

• Totally eliminate the danger of amp clipping burning out a tweeter or mid. You can also run a limiter on each driver to make sure they don’t get too much power.

• Allow you to perfectly time align the drivers

• Reduce amplifier IMD since the frequency range each amp covers is much smaller

• Increase the maximum output of the loudspeakers by around 3dB

• Running a high-pass filter just below the port tuning frequency will help protect the woofers from bottoming out if sub-bass hits the speaker (a problem with any ported design). This will save power and reduce distortion a bit when you’re playing loud music.

1. DSP crossover (or any other type of crossover) cannot eliminate the crossover lobing entirely if the drivers are not coaxial point sources. But if it's a coaxial point source design, then the lobing doesn't exist from the start, so passive filtering is more then enough to not get crossover related lobing with it.
So a crossover lobing is not there because of the crossover but because the driver arrengement is not coaxial point source.

2. This depends also on the passive crossover design. But since multi amping uses multiple amps, the total wasted electrical energy (due to amp losses) is often not reduced, compared to single amp and passive filtering.

3. Time align for a specific axis only, because the driver arrangement of this speaker is not coaxial point source.

4. Multiple amps don't necessarily reduce the amp-speaker interaction related IMD, it depends on many factors like what amps, drivers and filtering, crossover are used for both the active and the passive version of the speaker.

5. Active crossing or multi amping doesn't increase the maximum SPL of a speaker if the single amp have enough voltage and current to drive the passive version of the speaker to its maximum.

6. You can apply protective high-pass filter (with DSP, active analogue or even passive way) for the passive speaker too, similar to the active crossed.

 

[dualazmak]

Hello again, OP @NJ coffee roaster,

I would like to also recommend you, prior to starting your multi-amplifier exploration, establishing your own and consistent "Audio Reference/Sampler Music Playlist" consists of your preferred music tracks selected from various music genres, all in excellent recording quality.

For example, you may find my such reference playlist in the first post on my dedicated thread;
An Attempt Sharing Reference Quality Music Playlist: at least a portion and/or whole track being analyzed by 3D color spectrum of Adobe Audition

 

[bigguyca]

Already have 4 mono amps, considering grabbing 2 more (probably topping b100s) and swapping minidsp flex for htx to use the htx as an active crossover, one amp per driver, totally bypassing the f208 internal crossover. Curious how much improvement I could expect if I do this.

+zero or less.

 

[dfuller]

Interesting that Lake, Meyer Sound, Marani, Four Audio and Electro-voice are some of the pro audio companies making FIR processors. Then you have MiniDSP, DEQX, Legacy and Colinear offering hi-fi FIR processors. Hypex even makes plate amps that can run FIR filters. Also, it seems like any decent active speaker being introduced uses some form of FIR processing.

So, yeah, I guess the slow, but steady proliferation of FIR processing in audio as CPU power becomes cheap is because linear phase filters really suck.

Makes perfect sense.

No, no, not FIR that's the problem. It's the FIR plus brick wall filters.