active crossover for 2.1 stereo system - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 3Likes
  • 1 Post By Thunder240
  • 1 Post By Frank Derks
  • 1 Post By A9X-308
 
Thread Tools
post #1 of 18 Old 03-14-2016, 10:22 AM - Thread Starter
Member
 
Thunder240's Avatar
 
Join Date: Feb 2011
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 14
active crossover for 2.1 stereo system

Hi folks,

I'm currently using a dbx 223s as an active crossover a 2.1 home stereo. Setup is as follows:

Hegel HD12 DAC (run at reference volume) -> Adcom GFP-750 preamp -> dbx 223s Xover -> Odyssey Stratos Plus (highs) -> Ascend CMT-340SE (highs)
Outlaw LFM-1EX (lows, summed)

(Interconnects are balanced until the crossover. At the crossover, I use TS -> RCA to switch to unbalanced. I realize this means I don't derive any benefit from a balanced signal path.)

I've experimented with and without the crossover, and I prefer the setup with the crossover because I feel the speekers produce a more coherent sound, probably because both they and the amp are relieved of the low frequencies. Although I don't notice any distortion or coloration that the crossover introduces, I do notice that it raises the noise floor. When I contacted Harmon, and I was told that the elevated noise floor is likely a function of the signal levels being much lower than what the crossover was designed for (-10dBv versus +4dBu).

The three brands of active crossovers that I've seen recommended for home application are Bryston, Accuphase, and Marchand. The cheapest I've seen any of these used is $800, which is more than I'd like to spend (and that 800 price seems to have been an odd duck -- most ads are a lot higher). First question, has anyone had any experience with the NHT X2? It's available (used) for under $200, which is much more to my liking. How does its sound quality compare to the dbx (which I'm coming from) and to its pricier brethren? Second question, has anyone else had experience using a pro crossover in a hifi system, and what was your experience? Did you end up eventually replacing it with a more expensive crossover designed for home application in order to lower the noise floor or otherwise improve sound quality? What did you find?

Thanks for sharing your experiences!

---------------
Edit: I'm crossing at 65 Hz


Last edited by Thunder240; 03-14-2016 at 10:35 AM.
Thunder240 is offline  
Sponsored Links
Advertisement
 
post #2 of 18 Old 03-14-2016, 10:41 AM
Advanced Member
 
Join Date: Aug 2015
Posts: 605
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 330 Post(s)
Liked: 328
you can do it for less than 200$ using one of the minidsp units.

https://www.minidsp.com/applications...eo-2-way-xover

Im not the qualified to talk about the pros and cons of using one of these. I know it is a very powerful architecture but is a bit more hands on than a prepackaged xover
aschen is offline  
post #3 of 18 Old 03-14-2016, 10:54 AM - Thread Starter
Member
 
Thunder240's Avatar
 
Join Date: Feb 2011
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 14
Thanks aschen. I understand that the midiDSPs are very popular here. However i'd like to keep the signal downstream of my DAC entirely in the analog domain.

Not looking for any time-alignment or EQ functionality, just a high quality analog outboard crossover that is less noisy than my dbx and hopefully cheaper than the Bryston/Marchand/Accuphase!

Thunder240 is offline  
Sponsored Links
Advertisement
 
post #4 of 18 Old 03-14-2016, 11:02 AM
Advanced Member
 
Join Date: Aug 2015
Posts: 605
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 330 Post(s)
Liked: 328
Oh right I missed that requirement. I do't know much about pro equipment but I have read that some of it operates at higher peak signal voltages for the line level stuff.

I wonder if there are any high quality analog x-overs for automotive use that could be ran of a cheap 12v regulated supply?
aschen is offline  
post #5 of 18 Old 03-14-2016, 11:03 AM
Senior Member
 
Join Date: Oct 2015
Location: South Carolina
Posts: 316
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 133 Post(s)
Liked: 121
Quote:
Originally Posted by aschen View Post
you can do it for less than 200$ using one of the minidsp units.

https://www.minidsp.com/applications...eo-2-way-xover

Im not the qualified to talk about the pros and cons of using one of these. I know it is a very powerful architecture but is a bit more hands on than a prepackaged xover
I have one of those units that I'm using as a crossover to my subwoofer and as an EQ in my main system. Feature-wise very few units can beat it - the equalizer can either be a 31 band standard EQ or parametric, leading to the best adjustment possible (I've never seen an EQ go over 31 bands for each channel). The crossover is a true crossover, having separate adjustable high pass and low pass filters for each of the four output channels. Sound-wise - as far as I'm aware there is zero degradation of the signal. In fact, it improved my signal because it has zero noise that I can hear unlike my Pioneer 17 band analog EQ that it replaced.

It's by far one of the best purchases I have ever made and well worth asking price (plus the DSP software for $10). I use it in my main system as a crossover and EQ and then I load up my other file for settings for my second system and use it solely as an EQ there. As long as you have a Windows computer you can use with the software, it's not hard to setup, adjust and use. It doesn't need to be connected to the computer once it's set to your liking as it can run off pretty much any USB wall charger (mine's running off an old Motorola Droid X charger).

That's my opinion and experiences with it. I highly recommend it.

7.1 Setup: Yamaha RX-V671, Boston Acoustics VR40 (Mains), VR12 (Center), CR8 (Surrounds), CR8 (Rear Surrounds), Mirage Omni S10
Second 7.1 Setup: Yamaha RX-V663/Kenwood KR-5030 (Stereo), Boston Acoustics VR20 (Mains), VR10 (Center), CR6 (Surrounds), CRC (Rear Surrounds), Klipsch Sub12HG
2.1 Setup: Nakamichi RE-2, Boston Acoustics VR40 and Mirage Omni S10 (shared with 7.1), Emotiva XDA-1, and Pioneer, Kenwood, dbx, Luxman, Burwen, and JVC vintage equipment
TheNightwisher is offline  
post #6 of 18 Old 03-14-2016, 02:28 PM - Thread Starter
Member
 
Thunder240's Avatar
 
Join Date: Feb 2011
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 14
I appreciate you're sharing your experience with the miniDSP. I don't doubt that it will be quieter than the dbx, but I'm afraid of introducing new issues because of the additional A/D/D/A conversions going on. That said, if I ever have the chance to borrow one from a friend, I may A/B it against my dbx -- it's worth at least a no-cost audition at some point if the opportunity presents itself. For the moment, though, I'm looking for a 100% analog solution, not a DSP-based solution.
TheNightwisher likes this.

Thunder240 is offline  
post #7 of 18 Old 03-14-2016, 02:30 PM
Senior Member
 
clpetersen's Avatar
 
Join Date: May 2012
Posts: 464
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 216 Post(s)
Liked: 69
Quote:
Originally Posted by Thunder240 View Post
Thanks aschen. I understand that the midiDSPs are very popular here. However i'd like to keep the signal downstream of my DAC entirely in the analog domain.

Not looking for any time-alignment or EQ functionality, just a high quality analog outboard crossover that is less noisy than my dbx and hopefully cheaper than the Bryston/Marchand/Accuphase!
You can build your own high quality crossover:
http://sound.westhost.com/projects.htm

specifically this project:
http://sound.westhost.com/project09.htm

I have built two of Elliot's projects, though not the crossover itself. If you can read a schematic and use a soldering iron they are easy and well documented.

Otherwise, look for a used Bryston (10B-SUB).
clpetersen is offline  
post #8 of 18 Old 03-14-2016, 06:02 PM
AVS Forum Special Member
 
BGLeduc's Avatar
 
Join Date: Jan 2003
Location: Albuquerque
Posts: 5,879
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 2652 Post(s)
Liked: 2521
If you don't mind having a few unused channels, you may find a used Outlaw ICBM in your price range.

I have an NHT X2 as part of my Evolution sub system, but I have no idea how it compares to your dbx unit. One thing though, the High Pass has only three settings; 50, 80, and 120, IIRC.

Last edited by BGLeduc; 03-14-2016 at 06:10 PM.
BGLeduc is online now  
post #9 of 18 Old 03-18-2016, 02:13 PM - Thread Starter
Member
 
Thunder240's Avatar
 
Join Date: Feb 2011
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 14
Hey, it looks like there are several good ideas here for me to research. Thanks everyone!


Quote:
Originally Posted by BGLeduc View Post
I have an NHT X2 as part of my Evolution sub system, but I have no idea how it compares to your dbx unit. One thing though, the High Pass has only three settings; 50, 80, and 120, IIRC.
That's good to know about the X2's high pass filter. It looks like some of the others also share that 3-way frequency switch on the high pass. (Bryston 10B-SUB is an exception, but it costs 5 times more).

I will try tuning my dbx to 50 and 80 and see how they compare to 65, where it is currently set.
Thunder240 is offline  
post #10 of 18 Old 03-18-2016, 02:21 PM
 
lovinthehd's Avatar
 
Join Date: Dec 2007
Location: OROR
Posts: 16,231
Mentioned: 50 Post(s)
Tagged: 0 Thread(s)
Quoted: 4588 Post(s)
Liked: 4796
lovinthehd is offline  
post #11 of 18 Old 03-18-2016, 05:40 PM
AVS Forum Special Member
 
BGLeduc's Avatar
 
Join Date: Jan 2003
Location: Albuquerque
Posts: 5,879
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 2652 Post(s)
Liked: 2521
Quote:
Originally Posted by lovinthehd View Post
Surprised they still have these in stock. They have not made their TN subs for years. I still use a TN1225.

This is pretty old school stuff, having to set the crossover frequency with a plug in module.
BGLeduc is online now  
post #12 of 18 Old 03-19-2016, 05:21 AM
AVS Forum Special Member
 
Frank Derks's Avatar
 
Join Date: Jul 2002
Location: Region A,B,C
Posts: 2,487
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 539 Post(s)
Liked: 413
Quote:
Originally Posted by Thunder240 View Post
I appreciate you're sharing your experience with the miniDSP. I don't doubt that it will be quieter than the dbx, but I'm afraid of introducing new issues because of the additional A/D/D/A conversions going on. That said, if I ever have the chance to borrow one from a friend, I may A/B it against my dbx -- it's worth at least a no-cost audition at some point if the opportunity presents itself. For the moment, though, I'm looking for a 100% analog solution, not a DSP-based solution.

To be blunt, that's stupid. It is audiophoolery to believe that filtering in the analog domain is somehow better than a digital solution.


The miniDSP can operate at 24 bit with 96Khz sample rate. Even with the ad and da conversion it will operate with less noise and lower distortion.
You can also use a digital input on the miniDSP and eliminate the additional ad da conversion from the chain.


There is also the trick that improves the sub and mains integration.
With a measurement mike you can setup eq parameters using REW as measuring tool.
You can correct your main speakers to have a flat response down to 30Hz with the parametric equalizer option in the dsp.
You probably end up with a lot of gain to flat out the response down to 30Hz on your mains but that is not a problem because the crossover filter will attenuate the frequency range below the crossover frequency.
TheNightwisher likes this.
Frank Derks is offline  
post #13 of 18 Old 03-29-2016, 05:44 PM - Thread Starter
Member
 
Thunder240's Avatar
 
Join Date: Feb 2011
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 14
Quote:
Originally Posted by Frank Derks View Post
To be blunt, that's stupid. It is audiophoolery to believe that filtering in the analog domain is somehow better than a digital solution.


The miniDSP can operate at 24 bit with 96Khz sample rate. Even with the ad and da conversion it will operate with less noise and lower distortion.
You can also use a digital input on the miniDSP and eliminate the additional ad da conversion from the chain.


There is also the trick that improves the sub and mains integration.
With a measurement mike you can setup eq parameters using REW as measuring tool.
You can correct your main speakers to have a flat response down to 30Hz with the parametric equalizer option in the dsp.
You probably end up with a lot of gain to flat out the response down to 30Hz on your mains but that is not a problem because the crossover filter will attenuate the frequency range below the crossover frequency.
@Frank Derks

Thank you for your sharing your insight into how one can use the EQ capability of the miniDSP to achieve better integration of main speakers and sub. I can see why that method would work. Having said that, the rest of your post was out of line. I said nothing about the relative merits of digital vs analog filtering. You put words in my mouth. My issue is with the unnecessary conversions.

Two things are worth noting. First, if I use the digital input on the miniDSP, I’d lose the master volume on my preamp. Perhaps I could control volume digitally using software, but sound quality will suffer as I shave bits off the signal, and more importantly, from an ergonomic perspective I’d much rather use a pot to control my volume than a computer. So that’s a non-starter for me. If I use the miniDSP, it will be with analog inputs, and I’ll eat the extra A-D conversion. Every conversion from D to A involves filtering, and every conversion from A to D involves sampling. So yes, I prefer to avoid unnecessary conversions because they do affect the signal.

Second, you asserted that even with the extra conversions the miniDSP will operate with less noise and distortion than my current gear. Did you actually do the comparison, or are you just saying this because you believe it to be true? The miniDSP 2x4 distortion specs are 0.003% on the analog input and 0.001% on the analog output. I couldn’t find a noise spec. Not sure if those distortion numbers are additive when going A-D-D-A, but assuming they aren't, they are slighty better than the dbx (0.004%), comparable to the Bryston (0.003%) , worse than NHT on the hi-pass (0.001%) , and better than the NHT on the low-pass (0.01%). As for comparison to my current DAC (since you suggest I feed it with a digital signal), the Hegel has a noise floor of -145 db and a noise floor of 0.0005%. I’m curious about the miniDSP’s noise, and if you have it, please share it. I have no trouble believing that it produces less noise than my dbx, but so would an analog crossover that’s designed to take a -10dbv signal instead of a +4dbu. The Bryston’s SNR is -100dB, and the NHT’s is -105 dB.

To sum up, I’m not ruling out a digital crossover — I already said that I would happily borrow and evaluate a miniDSP in my system if an opportunity presents itself — but I’m not going to run out and buy one because of the two unnecessary conversions. You may not agree with me that this is significant, but it’s far from stupid. For everyone else who is reading this, I apologize for this rant, and thanks again for all of your ideas, including everyone who is encouraging me to consider the miniDSP.

Thunder240 is offline  
post #14 of 18 Old 03-30-2016, 06:58 AM
AVS Forum Special Member
 
Frank Derks's Avatar
 
Join Date: Jul 2002
Location: Region A,B,C
Posts: 2,487
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 539 Post(s)
Liked: 413
Quote:
Originally Posted by Thunder240 View Post
@Frank Derks

Thank you for your sharing your insight into how one can use the EQ capability of the miniDSP to achieve better integration of main speakers and sub. I can see why that method would work. Having said that, the rest of your post was out of line. I said nothing about the relative merits of digital vs analog filtering. You put words in my mouth. My issue is with the unnecessary conversions.
Your issue with 'unnecessary conversions' is a non issue. Why is it an issue? If the pro's outweigh the con's it doesn't matter that the ad da conversions are required.


Quote:
Originally Posted by Thunder240 View Post
Two things are worth noting. First, if I use the digital input on the miniDSP, I’d lose the master volume on my preamp. Perhaps I could control volume digitally using software, but sound quality will suffer as I shave bits off the signal, and more importantly, from an ergonomic perspective I’d much rather use a pot to control my volume than a computer. So that’s a non-starter for me. If I use the miniDSP, it will be with analog inputs, and I’ll eat the extra A-D conversion. Every conversion from D to A involves filtering, and every conversion from A to D involves sampling. So yes, I prefer to avoid unnecessary conversions because they do affect the signal.
The miniDSP has a solution for digital controlling the volume with a pot.


The shaving off bits off the signal is a myth. You do not shave bits of the signal. The resolution and noise floor stays exactly the same.


Quote:
Originally Posted by Thunder240 View Post
Second, you asserted that even with the extra conversions the miniDSP will operate with less noise and distortion than my current gear. Did you actually do the comparison, or are you just saying this because you believe it to be true? The miniDSP 2x4 distortion specs are 0.003% on the analog input and 0.001% on the analog output. I couldn’t find a noise spec. Not sure if those distortion numbers are additive when going A-D-D-A, but assuming they aren't, they are slighty better than the dbx (0.004%), comparable to the Bryston (0.003%) , worse than NHT on the hi-pass (0.001%) , and better than the NHT on the low-pass (0.01%). As for comparison to my current DAC (since you suggest I feed it with a digital signal), the Hegel has a noise floor of -145 db and a noise floor of 0.0005%. I’m curious about the miniDSP’s noise, and if you have it, please share it. I have no trouble believing that it produces less noise than my dbx, but so would an analog crossover that’s designed to take a -10dbv signal instead of a +4dbu. The Bryston’s SNR is -100dB, and the NHT’s is -105 dB.
Distortion numbers are additive. Noise from each device is not correlated giving an average noise figure that is slightly lower.
A CS4272 is for the AD conversion having a -100dB noise+thd and a dynamic range 114dB.
https://www.cirrus.com/en/pubs/proDa.../CS4272_F1.pdf
The dac options are a bit better.


However these noise and distortion numbers are at an inaudible level.
The point is that the filtering in the digital domain will yield a far better result with the added bonus of room correction that will make the biggest impact on your sound quality.




Quote:
Originally Posted by Thunder240 View Post
To sum up, I’m not ruling out a digital crossover — I already said that I would happily borrow and evaluate a miniDSP in my system if an opportunity presents itself — but I’m not going to run out and buy one because of the two unnecessary conversions. You may not agree with me that this is significant, but it’s far from stupid. For everyone else who is reading this, I apologize for this rant, and thanks again for all of your ideas, including everyone who is encouraging me to consider the miniDSP.
Frank Derks is offline  
post #15 of 18 Old 03-30-2016, 03:53 PM
AVS Forum Special Member
 
A9X-308's Avatar
 
Join Date: Mar 2008
Location: Australia
Posts: 8,321
Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 1792 Post(s)
Liked: 1484
I agree strongly with Frank's posts, especially #14. I've been using active xovers since the early 80's when I started designing and building them myself before going DSP in about 2001 so I have a bit of experience. The idea that the extra A/D/A makes an audible difference is audiophile foolishness.

Analog xovers are very limited in capacity: usually a single filter type and slope, no EQ, no delay and a method of setting frequency (rotary pots) that isn't very accurate as ganged pots have hopeless tracking. The dbx is a pretty poor example of them mainly because it uses TL074 opamps that the 1970s would like back. There are much, much better units today.

Quote:
Originally Posted by Thunder240 View Post
Hegel HD12 DAC (run at reference volume) -> Adcom GFP-750 preamp -> dbx 223s Xover -> Odyssey Stratos Plus (highs) -> Ascend CMT-340SE (highs)
Outlaw LFM-1EX (lows, summed)
I'm sure you like it, but it seems imbalanced cost wise. A $1400 DAC combined with $500 speakers is wrong to me. Speakers and room are 99% of the sonic experience. A modern DAC is a tiny percentage of what's left.

Quote:
Originally Posted by Thunder240 View Post
(Interconnects are balanced until the crossover. At the crossover, I use TS -> RCA to switch to unbalanced. I realize this means I don't derive any benefit from a balanced signal path.)
Balanced doesn't get you any benefit domestically either. Few devices actually have a useful CMRR in the audio band to make an audible difference, let alone wideband.

Quote:
Originally Posted by Thunder240 View Post
I've experimented with and without the crossover, and I prefer the setup with the crossover because I feel the speekers produce a more coherent sound, probably because both they and the amp are relieved of the low frequencies.
Theis is correct and one of the reasons I advocate for adding subs, even in 2ch systems.

Quote:
Originally Posted by Thunder240 View Post
Although I don't notice any distortion or coloration that the crossover introduces, I do notice that it raises the noise floor. When I contacted Harmon, and I was told that the elevated noise floor is likely a function of the signal levels being much lower than what the crossover was designed for (-10dBv versus +4dBu).
No one uses -10dbV for domestic units any more, though it was common for a long time back when. Since digital is by far the dominant medium, and CDPs (RBCD standard from 1981 is 2Vrms) and other domestic digital devices output around 1-2Vrms for 0dBFS (0 to +6dbV), why would you?

My advice: sell the Hegel and the dbx. Buy a MiniDSP HD and use the pot to control the level digitally. If you are willing to get your hands a little dirty with DIY, a 4ch preamp isn't difficult. Then you could sell the Adcom pre too.
TheNightwisher likes this.
A9X-308 is offline  
post #16 of 18 Old 03-30-2016, 05:12 PM
AVS Forum Special Member
 
nalthien's Avatar
 
Join Date: Nov 2006
Posts: 1,009
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 485 Post(s)
Liked: 537
One important consideration with MiniDSP is that it's voltage support is rather low (either 0.9v or 2.0v controlled by a switch in the Mk II model). I don't know the specs of your preamp; but, I'm not able to use mine with my preamp as it's rated for 5v output.

Not trying to dissuade--it's a great product that I wish I could use.

Music: McIntosh C1100T/C | McIntosh MC452 | Revel Salon 2 | PSA S3000i x2 | VPI Traveler | Parasound ZDac | AppleTV
Movies Add: Marantz AV7702 | Revel Voice 2 | Emotiva UPA-1 | Sony Ps4 | Custom HTPC
Ordered: VPI Prime
nalthien is offline  
post #17 of 18 Old 03-30-2016, 06:22 PM
AVS Forum Special Member
 
A9X-308's Avatar
 
Join Date: Mar 2008
Location: Australia
Posts: 8,321
Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 1792 Post(s)
Liked: 1484
Quote:
Originally Posted by nalthien View Post
I don't know the specs of your preamp; but, I'm not able to use mine with my preamp as it's rated for 5v output.
5V will be it's maximum. Have you actually tested it with your source playing a 0dBFS signal to see what it is?
The solution in to add a series resistor as the CODEC is current input: all the input selector does is change the value of the internal resistor. The original 2x4 at least, I haven't looked at the chipsets in the new HD units yet.
A9X-308 is offline  
post #18 of 18 Old 03-30-2016, 06:29 PM
AVS Forum Special Member
 
nalthien's Avatar
 
Join Date: Nov 2006
Posts: 1,009
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 485 Post(s)
Liked: 537
Quote:
Originally Posted by A9X-308 View Post
5V will be it's maximum. Have you actually tested it with your source playing a 0dBFS signal to see what it is?
I have not measured it; but, on RCA (I forgot I was quoting balanced numbers) it's rated for 2.5V with a max of 8V. (5V and 16V balanced)

Music: McIntosh C1100T/C | McIntosh MC452 | Revel Salon 2 | PSA S3000i x2 | VPI Traveler | Parasound ZDac | AppleTV
Movies Add: Marantz AV7702 | Revel Voice 2 | Emotiva UPA-1 | Sony Ps4 | Custom HTPC
Ordered: VPI Prime
nalthien is offline  
Sponsored Links
Advertisement
 
Reply 2-Channel Audio

Tags
2.1 speaker setup , active crossover , professional

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off