Active Analog vs DSP Crossover

Nick V · « **on:** 8 Sep 2018, 06:49 pm »

I'm looking for the best solution for actively crossing over between my 3-way monitors (Selah Audio Vigore - ScanSpeak beryllium tweeters, Satori 5" mid, SB Acoustics 8" woofers) and a pair of Rythmik FM8 active subwoofers for a music system. Crossing around 100Hz I'm guessing. I run a hybrid system that also runs double duty as an HT System (with separate signal paths). I use the HT bypass input in my Wyred4Sound STP-SE preamp for integration.

My big question is active analog vs DSP crossover, which is better?

The problem (as I see it) is that I have invested quite a bit of money (and effort) into my fully balanced 2 channel system with a clean signal path.

I run all digital inputs (chromecast audio running Roon, Oppo BDP83) into a miniDSP DDRC-22D for Dirac Live digital room correction. Then I send the coax digital output out of the miniDSP into my Esoteric SA-50 SACD Player/DAC. The fully balanced output from the Esoteric goes into my fully balanced Wyred4Sound STP-SE preamp and then into a Krell KAV-250a power amp (you guessed it, fully balanced).

There aren't a whole lot of fully balanced active crossovers on the market (that I'm aware of). Even the Bryston 10B Balanced version is single-ended internally. I don't want to use a cheap active crossover and corrupt the clean balanced signal coming through the entire signal chain.

I know that Marchand can make a fully differential balanced version of their XM-44 crossover, and he can even use OPA627 or Burson discrete op-amps (for a price). This option isn't cheap but it seems to be my best option that I'm considering on the analog side (w/ the Burson discrete op-amps). This option would be the easiest as I use the W4S preamp's HT Bypass input to integrate my HT system, and the rest of the system stays the same.

The other option is: sell the Esoteric DAC and the W4S Preamp and try to find a used Accuphase DF-45/55/65 (or something siilar) for a somewhat reasonable price.

I can send the digital output from the miniDSP right into the Accuphase then the fully balanced DAC outputs out of the Accuphase directly into the Krell amp and the pair of Rythik FM-8 subwoofers. Then I'm relying on the digital volume control in the miniDSP to control the system volume which might not be the best. One advantage is that these Accuphase units have 4-way active functionality, so I could eventually have the entire system as a 4-way active system including the 3-way Selah monitors (I would just need to add some amplification channels).

I might have an issue integrating the HT system with this route. The Accuphase units do have analog XLR and RCA inputs, but I'm not sure that I'd be able to properly integrate and calibrate the HT system running into one of those inputs.

Any opinions or experience either way?

Speedskater · « **Reply #1 on:** 8 Sep 2018, 09:26 pm »

For a loudspeaker design engineer, an active analog, DSP crossover or passive crossover can all sound the same.
But a modern DSP crossover gives the designer more tools to do the job. And for a complex xover the DSP will be at less cost.
For a DIY designer, the DSP allows several different scenes to programed in. Then someone else can randomly chose one and you can listen blind.

Mark Korda · « **Reply #2 on:** 8 Sep 2018, 10:10 pm »

Hi Nick,
I too wanted the clean path of my amp as untouched as possible when I hooked my sub woofer up. The solution is to use Y cables. My cd player goes to my vacuum tube amp for the high end and also to the sub woofer without any electronic crossover in the path.
My sub has an amp, BASH from Parts Express that will cut off the frequencies above 150 hz so that the only thing in the way of the signal from the cd or what have you is the Y cable it's self. Most sub amps have this feature or a volume and frequency control. It works great for me and there are some good Y cable deals in Audio Advisor, the catalog....Mark Korda

Nick V · « **Reply #3 on:** 8 Sep 2018, 10:33 pm »

Hi Mark,

I use REW for measurements and Dirac Live, and one thing that is very evident in my room, is that when I'm running the monitors full range AND overlapping the subwoofers, it wreaks havoc on the measured (and subjective) performance in my system. My preamp has two sets of balanced outputs and two sets of single ended outputs. I think the issue (especially that the monitors are ported and the subwoofers are sealed) is that at some frequencies the monitors and the subwoofers are in phase and at some frequencies they're out of phase with each other. This causes significant peaks and cancellations in the frequency response in my system.

The reason I want to add an active crossover (analog or DSP) is so that I'm not just low passing the subwoofers, but also high-passing the speakers. This also gives the speakers more headroom and lowers distortion by allowing them to play in the range where the woofer is most effective. I'm thinking that since the Rythmik subs are so good, and the servo control seems to make such a big difference with the bass frequencies, that I'll be high-passing the monitors around 80Hz-100Hz (even though they can play down to ~ 30Hz).

Speedskater · « **Reply #4 on:** 8 Sep 2018, 10:46 pm »

Don't confuse a balanced interconnect system with a balanced internal circuit in a component. A balanced interconnect system is always an excellent choice. While a balanced internal circuit is a reasonable engineering choice for a power amplifier, it's a poor choice for an active crossover. It doubles the parts count and many of those parts need to be of close tolerance. So it could increase distortion and frequency errors.

Nick V · « **Reply #5 on:** 8 Sep 2018, 11:28 pm »

The source, the preamp and the power amp in my system are all fully balanced, so I figured it would be best to keep the crossover differential balanced as well. No?

The Marchand can either be built with balanced inputs, or fully differential balanced.

JohnR · « **Reply #6 on:** 9 Sep 2018, 02:16 am »

You are already using the DSP to do the room correction, the volume control is just an extra step in the digital processing.

JLM · « **Reply #7 on:** 9 Sep 2018, 11:26 am »

The miniDSP DDRC-22D is a weak link (not balanced). Consider simplifying by moving to the new $1200 miniDSP SHD (server, DAC, preamp, Dirac Live DSP, microphone and remote included) that has network, USB, coax, AES/EBU digital inputs, one pair each of XLR/RCA analog inputs, four XLR analog outputs, four RCA analog outputs and can be configured for 2 mains plus 2 subs with selectable high and low pass filters. Then you could lose the DDRC-22D, Chromecast, Oppo, Esoteric, and Wyred4Sound while forgetting about the Bryston and Accuphase.

You'd end up with sources inputing to the miniDSP SHD which would feed the Krell/Selahs and Rythmiks. Done. Easy/pleasy. Just gotta learn to setup the miniDSP SHD.

Nick V · « **Reply #8 on:** 9 Sep 2018, 01:29 pm »

I am considering the SHD, I've been asking some questions in the miniDSP forum as well.

I'm not following on the 22D not being balanced though. It's digital in,digital out ( no A/D or D/A conversion at all) and it feeds a 96/24 coax digital signal to the dual differential DAC section in the Esoteric.

The DAC & analog output section in the SHD is surely a step down from the Esoteric, no?

Even with the SHD I would use one pair of analog XLR outputs (using the internal DAC) for the low passed room corrected signal to the subwoofers. But I would still use a coax digital output from the SHD into the Esoteric for the high passed room corrected signal. Then I could get rid of the Wyred4Sound preamp.

The SHD does look like a great option though. I hope they make it a Roon endpoint.

poseidonsvoice · « **Reply #9 on:** 9 Sep 2018, 03:12 pm »

Quote from: Nick V on 8 Sep 2018, 10:33 pm

Hi Mark,

I use REW for measurements and Dirac Live, and one thing that is very evident in my room, is that when I'm running the monitors full range AND overlapping the subwoofers, it wreaks havoc on the measured (and subjective) performance in my system. My preamp has two sets of balanced outputs and two sets of single ended outputs. I think the issue (especially that the monitors are ported and the subwoofers are sealed) is that at some frequencies the monitors and the subwoofers are in phase and at some frequencies they're out of phase with each other. This causes significant peaks and cancellations in the frequency response in my system.

The reason I want to add an active crossover (analog or DSP) is so that I'm not just low passing the subwoofers, but also high-passing the speakers. This also gives the speakers more headroom and lowers distortion by allowing them to play in the range where the woofer is most effective. I'm thinking that since the Rythmik subs are so good, and the servo control seems to make such a big difference with the bass frequencies, that I'll be high-passing the monitors around 80Hz-100Hz (even though they can play down to ~ 30Hz).

Nick,

It seems that your entire premise for posing the question regarding digital DSP active XO vs. analog XO is your dissatisfaction with your sub/mains/room integration. As such, do you mind posting your measurements on the acoustics circle? Perhaps we can advise on some tweaks depending on how flexible your current 2ch listening situation is. And the more I learn about DIRAC the more impressive it seems although I will say there are solutions in audio that belong in the electrical domain and solutions that belong in the acoustical domain. Some acoustical anomalies can never be fixed in the electrical/DSP/DIRAC domain...

Of course a way to circumvent all these issues is to start with a clean slate. Get a JBL LSR708, or JBL M2, or Kii 3 , or Genelec S360 SAM, or Dutch & Dutch 8C, or perhaps Spatial X1/X2, etc...and be done. But running the HT side of things can be challenging there since you want to have a setup that serves both HT/2ch.

Best,
Anand.

Nick V · « **Reply #10 on:** 10 Sep 2018, 02:13 am »

Quote from: poseidonsvoice on 9 Sep 2018, 03:12 pm

Nick,

It seems that your entire premise for posing the question regarding digital DSP active XO vs. analog XO is your dissatisfaction with your sub/mains/room integration. As such, do you mind posting your measurements on the acoustics circle? Perhaps we can advise on some tweaks depending on how flexible your current 2ch listening situation is. And the more I learn about DIRAC the more impressive it seems although I will say there are solutions in audio that belong in the electrical domain and solutions that belong in the acoustical domain. Some acoustical anomalies can never be fixed in the electrical/DSP/DIRAC domain...

Best,
Anand.

I see what you're getting at. Unfortunately I have a 2 year old daughter, and a wife that doesn't share my passion for hi-fi so I have pretty much no flexibility with my setup in the mixed use space that the system currently resides. I'm basically using room treatments and Dirac Live to try to fix the issues with my room and placement. The speakers are pulled out as far as I can from the rear wall and the music subwoofers are right beside the main speakers. I also have a pair of "LFE/Summed bass" subwoofers for the HT system, that are out of the chain in the 2 channel signal path.

I'm already pushing it with my wife, lol. The room is decently well treated with GIK Acoustics panels, this Post shows you how the room is treated (with my old system). A lot has been upgraded since then.

Funny that you mention studio monitors, I've used monitors in my desktop and bedroom systems in the past with fantastic results. I'm currently using Dynaudio BM6a mkII active monitors in my desktop system (with a Paradigm Monitor SUB 10 subwoofer). The Dynaudios make it easy to integrate the sub though, they include an 80Hz high-pass option with a simple switch (and the Paradigm SUB10 has Paradigm PBK functionality which also helps to tame the room).

Tyson · « **Reply #11 on:** 10 Sep 2018, 02:15 am »

http://www.firstwatt.com/b4.html

nickd · « **Reply #12 on:** 10 Sep 2018, 03:57 am »

I am a fan of DSP and active crossovers. That said, quality is still important. I went with Lyngdorf because I wanted the DSP “room perfect” correction software / hardware in a small package. The adjustable digital crossover was just a bonus.

You can put a passive filter on the imput of the Krell that will get you closer to your goal. There are some pro companies that make passive inline filters in XLR. They sound clean and are reasonable in cost.

Subs are more of a tricky beast. Advanced DSP room correction is not for the average tube roller I agree, but it can clean up a lot of mud. Several companies are moving in that direction because the technology is matured and cost is now reasonable. That and it works really well.

HT cOz · « **Reply #13 on:** 10 Sep 2018, 04:38 am »

As much as you like your current gear, you might want to think about selling it all and going all in on active with these guys. http://www.analog-precision.com/ They can even build the amp using Hypex models and I bet Rick would do the fade program.

Also don’t forget that enjoying music and home theater is the point. It’s very easy to get caught in a perpetual upgrade/change journey and miss out on enjoying life. Audio isn’t worth making your wife angry or losing time with your kids. Just saying..,

JLM · « **Reply #14 on:** 10 Sep 2018, 11:47 am »

Quote from: Nick V on 9 Sep 2018, 01:29 pm

I am considering the SHD, I've been asking some questions in the miniDSP forum as well.

The DAC & analog output section in the SHD is surely a step down from the Esoteric, no?

Only a side by side listen could determine that but don't dismiss out of hand the advancements made in digital in recent years. For instance just read reviews from say 4 years ago that sound absolutely primitive by today's standards. Whatever digital you buy today will be obsolete in 5 years. That's not to say chips are everything or that build quality means nothing, but digital is disposable, so no point in paying for chiseled faceplates or other boutique bling. Analog (tubes and vinyl) are dead.

BTW I moved from Dynaudio BM5 MkIIIs to JBL 708Ps a couple of months ago. I liked the Dyn's but love the 708P's, which I should for the price/size difference. So I'm in a similar boat, looking for a new DAC/preamp/DSP, so would like to love the SHD too. But as you say how good can a $500 DAC (if the $1200 price is roughly broken down for each component) be? That's why I eagerly await comparative reviews of this, and the RME ADI-2 DAC (as I've recently moved my GIK 244 panels around and have tamed the worse speaker/setup/room anomalies). The ADI-2 DAC is prosumer and should be higher build/sound quality for $100 less. And for what little correction I need, the 708Ps should be able to handle that reasonably well.

Nick V · « **Reply #15 on:** 10 Sep 2018, 09:45 pm »

Quote from: HT cOz on 10 Sep 2018, 04:38 am

As much as you like your current gear, you might want to think about selling it all and going all in on active with these guys. http://www.analog-precision.com/ They can even build the amp using Hypex models and I bet Rick would do the fade program.

Also don’t forget that enjoying music and home theater is the point. It’s very easy to get caught in a perpetual upgrade/change journey and miss out on enjoying life. Audio isn’t worth making your wife angry or losing time with your kids. Just saying..,

No doubt about that. Balance is certainly the key.

I definitely don't get to enjoy my systems as often as I used to, but when I do sit down in the sweet spot with a nice glass of wine or a scotch (even if it's only for a few songs) I want to just enjoy the music instead of worrying about measurements, upgrades, etc... I feel like my system is almost there, just need a solution for smoothly integrating the stereo music subs and the mains, and I'm all set for a good while. The system sounds fantastic as it is, but this is the last planned upgrade as the rest of the system has pretty much been upgraded in the past year or so.

JDUBS · « **Reply #16 on:** 11 Sep 2018, 04:13 am »

Quote from: JLM on 10 Sep 2018, 11:47 am

Only a side by side listen could determine that but don't dismiss out of hand the advancements made in digital in recent years. For instance just read reviews from say 4 years ago that sound absolutely primitive by today's standards. Whatever digital you buy today will be obsolete in 5 years. That's not to say chips are everything or that build quality means nothing, but digital is disposable, so no point in paying for chiseled faceplates or other boutique bling. Analog (tubes and vinyl) are dead.

BTW I moved from Dynaudio BM5 MkIIIs to JBL 708Ps a couple of months ago. I liked the Dyn's but love the 708P's, which I should for the price/size difference. So I'm in a similar boat, looking for a new DAC/preamp/DSP, so would like to love the SHD too. But as you say how good can a $500 DAC (if the $1200 price is roughly broken down for each component) be? That's why I eagerly await comparative reviews of this, and the RME ADI-2 DAC (as I've recently moved my GIK 244 panels around and have tamed the worse speaker/setup/room anomalies). The ADI-2 DAC is prosumer and should be higher build/sound quality for $100 less. And for what little correction I need, the 708Ps should be able to handle that reasonably well.

Audioscience did some measurements of the shd a couple of weeks back. Mine should be here tomorrow and I'm looking forward to giving it a shot in my system.

-Jim

JLM · « **Reply #17 on:** 11 Sep 2018, 10:11 am »

Quote from: JDUBS on 11 Sep 2018, 04:13 am

Audioscience did some measurements of the shd a couple of weeks back. Mine should be here tomorrow and I'm looking forward to giving it a shot in my system.

-Jim

Yep, read that (at least twice), they report lots of noise/jitter. And it seems like the developers are still working on that issue and the unit in general. Is this a beta release? Once the dust settles and comparative reviews come in I'll be very interested.

But please do report back. BTW what will you be comparing it to?

sorry for highjacking of the thread

Nick V · « **Reply #18 on:** 11 Sep 2018, 01:37 pm »

Quote from: JDUBS on 11 Sep 2018, 04:13 am

Audioscience did some measurements of the shd a couple of weeks back. Mine should be here tomorrow and I'm looking forward to giving it a shot in my system.

-Jim

I'm very interested to hear how you like it. I'm thinking I'll sell the Wyred4Sound STP-SE Preamp and the miniDSP DDRC-22D, buy the SHD and come out ahead. I'll keep the Esoteric and use the analog XLR outs in the SHD for the subs, and the coax digital out into the Esoteric's dual-mono differential DACs for the mains.

AJinFLA · « **Reply #19 on:** 11 Sep 2018, 02:49 pm »

How are the Rythmiks being fed in this 2ch/HT system? They have a low pass filter (even on the LFE input), so unless I'm missing something, the only thing you are missing is a high pass for the main speakers?