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David Ketley
02-11-2016, 12:30 PM
Active crossovers.
Iím using a Marchand XM 44 3 way crossover and am reasonably happy with the result but it has severe limitations when compared to modern DSP.
One of the weak links in the chain of DSP is the DAC it has a huge influence on the music.
I suppose the ultimate digital system would be to output four channels of digital from a DSP into four DACs of choice but would this be worth the expense?
I wonder if anyone has solved this dilemma?

Thanks

David

SteveJewels
01-23-2017, 01:24 PM
Hello David,

I hope that you are well.

I realize that this is an old thread but the topic is germane to my project so I am giving it a go. Perhaps you or someone else can expound on the "severe limitations when compared to modern DSP?"

Thanks!

Best regards,

Steve

Ed Zeppeli
01-23-2017, 01:45 PM
I suppose one of the potential downfalls of outboard DSP boxes (Behringer, Driverack, BSS, XTA etc...) is that if you're using the crossover functions of the DSP you are bound to the internal DAC of the processor.

If the processor has the option to output multiple channels digitally then one could get external DACS of their preference to use between the DSP and the amps. I'm not sure if this is an option on many/any of them.

Regards,

Warren

JeffW
01-23-2017, 03:48 PM
Hello David,

I hope that you are well.

I realize that this is an old thread but the topic is germane to my project so I am giving it a go. Perhaps you or someone else can expound on the "severe limitations when compared to modern DSP?"

Thanks!

Best regards,

Steve



Severe limitations might include lack of delay (no way to time align drivers electronically), lack of parametric and/or graphic EQ, less flexibility on crossover frequencies/slopes - DSP stands for "digital signal processing", so analog active crossovers lack all aspects of digital signal processing. The upside being that it doesn't subject the signal to the A/D - D/A conversion process.

David Ketley
01-24-2017, 02:48 AM
I started my design of a 4 way active system with the intention of using an Analogue Active crossover namely the Marchand XM 44. I wanted as simple a system as possible using drivers in there best frequency range (and cost) without EQ or delay hence a 4 way system. Each driver is free to be moved to give the correct time alignment at the listening point. It was very apparent to me that the DAC plays a very important part in the final sound but in the end there are budget constraints so I believe the sound I have is very listenable to though I have not had accurate measurements of the response curves. There are High end multiple output Dacs out there but its a huge commitment on a unit where the advance in sound quality seems to be changing rapidly with the higher DSP formats being developed. Also there are now Amplifiers that will also give you a DSP facility. Room size, shape, and construction plays a major part in the final result, design your system for your space rather than trying to EQ it flat afterwards.

Looking at other Forums like Diyaudio its very apparent how obsessive this audio thing can be, in the end we should be listening to music there is no such thing as the ultimate sound other than a live performance in a good venue.

Dave

SteveJewels
01-24-2017, 04:39 AM
I suppose one of the potential downfalls of outboard DSP boxes (Behringer, Driverack, BSS, XTA etc...) is that if you're using the crossover functions of the DSP you are bound to the internal DAC of the processor.

If the processor has the option to output multiple channels digitally then one could get external DACS of their preference to use between the DSP and the amps. I'm not sure if this is an option on many/any of them.

Regards,

Warren

Thanks to all for responding.

I remember reading a paper a while ago on DSP's. There was quite a bit of discussion on DAC clock jitter and A2D-D2A clocks synchronization.

David, I am doing something like you said you started out doing. First though, I built a turntable.

Best regards,

Steve

Dave M
01-24-2017, 11:18 AM
What I do is, a Mac computer (All music files and Tidal played back through Audirvana, then the signal sent to pro audio EQ plugin for EQ and X-over purpose) + ProAudio 8ch DA converter. If you have a computer, you can start this for very cheap (but excellent sound quality), then you can upgrade DA and filter plugin to high end ones (ultimate quality).

IMO, the key for the successful active set up is not DA nor filter quality, but how to set filter and EQ. If the speaker sounds bad with cheap DA and digital filter, I don't think more expensive DA or filter will improve the sound. Compared to the filter curve, everything else is trivial. You will be surprised to hear how 0.3 dB cut or boost at a certain frequency affect the overall sound quality.

Mr. Widget
01-24-2017, 12:42 PM
IMO, the key for the successful active set up is not DA nor filter quality, but how to set filter and EQ. If the speaker sounds bad with cheap DA and digital filter, I don't think more expensive DA or filter will improve the sound.I agree that analog and digital equalization is not a simple thing and I have been to numerous friends' and customers' homes where bypassing the EQ was an immediate improvement due to poor setup.

That said, with either type there is a wide range of sonic performance levels available and the better either is, the better the results will be assuming the corrections are well chosen.


Widget

Ed Zeppeli
01-24-2017, 01:04 PM
I agree that analog and digital equalization is not a simple thing and I have been to numerous friends' and customers' homes where bypassing the EQ was an immediate improvement due to poor setup.



I can attest to this. The learning curve is steeper than the slopes being applied.

David Ketley
01-24-2017, 01:23 PM
I can attest to this. The learning curve is steeper than the slopes being applied.

Not my words but very much what I believe:

While I have a plethora of test equipment such as LMS which will run gated frequency responses to duplicate anechoic conditions, spectrum analysers, and a Tektronix distortion analyser, none of these marvels of electronics have ears. Sometimes, speakers with the most bizarre curves can produce a most incredible sound, especially if the listener hasn't seen the curves before listening to the speaker - preordained conclusions. We seem to have an innate ability to convince ourselves of that which doesn't exist or the nonexistence of that which does. I've come to the conclusion after decades of audio experiences that if so called aficionados spent less time listening to their equipment, they would, as you so eloquently said, "give themselves a treat and find something they've been missing". The music.

Dave

Ed Zeppeli
01-24-2017, 01:30 PM
Not my words but very much what I believe:

While I have a plethora of test equipment such as LMS which will run gated frequency responses to duplicate anechoic conditions, spectrum analysers, and a Tektronix distortion analyser, none of these marvels of electronics have ears. Sometimes, speakers with the most bizarre curves can produce a most incredible sound, especially if the listener hasn't seen the curves before listening to the speaker - preordained conclusions. We seem to have an innate ability to convince ourselves of that which doesn't exist or the nonexistence of that which does. I've come to the conclusion after decades of audio experiences that if so called aficionados spent less time listening to their equipment, they would, as you so eloquently said, "give themselves a treat and find something they've been missing". The music.

Dave

Important to not forget what this is all about and I agree it's easy to get lost in the tech.

Dave M
01-24-2017, 03:05 PM
Mr. Toole always insists that flattest response curve is the best sounding curve, and I agree with him, but it is not always true in real world situation. For example, high end roll off curve has to be set correctly (B&K 1974 or such), and the room and directivity character has to be compensated "by ear", and it's not a trivial task. Speaker voicing is an art form.

Here is my current conclusion for practical active EQ: Make on axis response as flat as possible (not easy at all), and start editing the curve from there (extremely sensitive task). :)

David Ketley
01-25-2017, 12:36 PM
exaSound e28 Multichannel USB DAC.

Has anyone tried one of these in a 4 way active system?
Dave

Dave M
01-25-2017, 01:01 PM
exaSound e28 Multichannel USB DAC.

Has anyone tried one of these in a 4 way active system?

Dave

Not me. Why are you interested in this unit?
This is not a professional unit and I guess it is probably very pricy for what it is.

Professional computer audio interface market is very matured and competitive, so I personally would choose one for pro studio use that also includes ADC (for measurement and analog connection purpose). ie. Prism, Apogee, Mytek, Lavry, RME, Steinberg, UAD, Lynx...

Dave M
01-25-2017, 01:08 PM
And one thing that should be carefully considered when choosing USB or firewire interface is the quality of the driver software. DAC comes with bad driver (very common) is nothing but nightmare. I (and any professionals) wouldn't never buy DAC from unknown company because of this reason. Companies that has a good reputation is, RME, Steinberg and UAD etc. The best place to check the reputation is Gearslutz.

sebackman
02-14-2017, 04:24 AM
The ADC’s today are so good so you won’t lose much there compared to the advantage to be able to correct frequency response, phase and timing. One needs to pick the battles.

If you decide to go the BSS route the London Soundweb units can be equipped with digital input and digital output to allow use of your favourite DAC’s. They can do balanced (or single end) SPDIF and AES in and out.

Regarding clocking I wrote some thoughts here.
http://www.audioheritage.org/vbulletin/showthread.php?38798-New-toy-for-all-M2-BSS-Crown-and-others-with-BLU-link-input-devices&p=396183&viewfull=1#post396183 (http://www.audioheritage.org/vbulletin/showthread.php?38798-New-toy-for-all-M2-BSS-Crown-and-others-with-BLU-link-input-devices&p=396183&viewfull=1#post396183)

and here

http://www.audioheritage.org/vbulletin/showthread.php?38716-Is-Good-DAC-Still-Necessary-With-DSP-Sound-Processor&p=399635&viewfull=1#post399635 (http://www.audioheritage.org/vbulletin/showthread.php?38716-Is-Good-DAC-Still-Necessary-With-DSP-Sound-Processor&p=399635&viewfull=1#post399635)


Kind regards
//Rob

Jazzhd
10-03-2017, 06:11 PM
exaSound e28 Multichannel USB DAC.

Has anyone tried one of these in a 4 way active system?


Dave

Hi Dave,
I started my system with the Exasound e28 and moved eventually to the e38 (using the Sabre 9028). My adc part is done with the Motu 828x using Thunderbolt connection.
Bottom line, I am very happy with the quality of this DAC.
Jazzhd.

onliner
11-13-2017, 03:45 AM
I personally would choose one for pro studio use that also includes ADC.