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Hi guys, thanks for dropping in. My system is a work in progress. This is what it looked like as of last month:

 

post-104440-0-69412200-1467023180_thumb.

 

When I started, it was a fairly conventional source - preamp - power amp - speaker system. As you can see, it has been converted to run active, with each driver having its own power amplifier. The reason I made all these changes is because the horns and tweeter never sounded as if they were tied in with the bass driver.

 

You may also note that the upper frequencies are handled by the Marchand (an active analog crossover) with the bass handled by a DEQX. Why not use the DEQX for the whole system? I can't tell you why the DEQX sounds worse, it just does. I think it has something to do with the analog to digital conversion that sucks the life out of the sound. Dynamics sound compressed, and music sounds limp and uninvolving. However, it DOES bring with it some benefits - once the drivers are time aligned and driver and room correction applied, the sound has a coherence that the analog crossover can't match. 

 

For a few years now I have had to choose which compromise I was willing to accept. Use the DEQX full time? Or live with a less coherent system with the Marchand not being able to perform DSP?

 

In the end, I settled for the Marchand handling the high frequencies, with the DEQX performing bass correction duties for the subwoofer only. This still has drawbacks, the most serious being the 20ms processing overhead that the DEQX introduces with respect to the Marchand. This exacerbates the time delay of the subwoofers, which is already time delayed compared to the main system. Note that the Haas effect states that any sound arriving more than 20ms after the main signal is perceived by the brain to be separate from the main signal. So you can imagine what the system sounds like - the upper frequencies sound wonderful, but it is accompanied by a plodding bass line. In short - it sounds a bit weird. 

 

So it was with great interest that I read Blizzard's contribution in WBF nearly a year ago: http://www.whatsbestforum.com/showthread.php?18648-The-best-way-possible-to-build-an-active-system

 

In it, Blizzard suggested a computer based crossover using a multi-channel NADAC DAC for output directly to some power amps. All I would have to do is to build a PC and purchase enough DAC's for output. I spent some months reading up as much as I could on computer audio and Acourate. It also helped a great deal when @Sir Sanders Zingmore (who also lives down the road from me) came over with his friend Aris and demonstrated Acourate on my system.

 

It is a cliche to say that I was blown away, but this was one of the big eye opening moments in my hifi journey. They brought over a little Raspberry Pi, and took a rough measurement of my system. Aris loaded the filter into the Pi, and away they went. With my own MPS-5 performing the DA conversion, I could not believe how coherent the system sounded. Even with this modest hardware (and albeit not having an ADC step and using a much superior DAC), it left the DEQX in the shade.

 

The little Raspberry was struggling to perform on the fly conversion. From time to time it would hiccup. Aris assured me that if I had a more powerful PC, and if I let Acourate perform the crossover function and thus have even more control of my system, I would get even more of a benefit.

 

So now I was fully convinced. One month ago, I finally bought all the parts required for the PC and now my system looks like this:

 

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Now the PC is the source, and I am using my Playback Designs MPS-5 as a DAC. I would prefer to use the MPS-5 as a transport, however it is not possible to use the optical drive as a transport AND get it to perform D-A conversion at the same time. To get me up and running, I am using the optical drive on the PC as a transport.

 

Eventually I will switch to using files stored in the PC's SSD as the source, but given that I have more than 4000 CD's, of which only half have been ripped, this isn't going to happen any time soon. For now and the immediate future, I will still need an optical drive. My hobby is listening to music, not sitting in front of my computer for hours upon hours for weeks on end mindlessly feeding CD's for ripping!

 

For those curious about the PC, this is the recipe:

 

CPU: Intel i7-6700K

Mobo: MSI B150I Gaming Pro Mini-ITX

RAM: Corsair Vengeance 2133 2x 8GB

Storage: Samsung 850 Evo 1TB SSD

Case: Streacom FC10 Alpha fanless (capable of dissipating the 95W TDP the i7-6700K produces)

 

Other:

- RME HDSPe AES sound card

- Dell S2240T touch screen monitor

 

Software:

- Windows 10 Home edition

- Acourate (to generate filters)

- HQPlayer (to upsample and perform convolution)

 

After I gathered all the hardware together and purchased all the licenses, I eagerly fired up the system when BANG one of the power amps decides to let out the magic smoke. As of right now I am twiddling my thumbs, waiting for the power amp to be repaired before I can get started taking measurements and generating DSP filters. Hopefully the power amp will return this week and I can finally get started.

 

I bought a HQPlayer license because HQPlayer is able to generate crossovers directly, apply Acourate generated convolution filters, and upsample to quad DSD. According to others, it sounds superior to on-chip upsampling. I can't tell you either way myself, I have the license but I haven't listened to it yet!

 

You may also notice that there is a new subwoofer in there. I bought four Rythmik Audio 12" drivers and I am getting a Paul Spencer to build and test the sub for me. This should also hopefully be an improvement over the JL Audio F110's.

 

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In the future, the PC will become a fully functional crossover. I have yet to decide on which multi-channel DAC to buy, but at this stage it will probably be the Merging+ NADAC. Or maybe the Merging+ Hapi. 

 

At the moment, I am not sure how I would take measurements once the NADAC is purchased and the crossover is implemented. I am currently discussing this with the author of Acourate, Dr. Uli Brueggemann on the Acourate forum.

Edited by Keith_W

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This is almost the final configuration of the system. 

 

Amfibius-System-NADAC.jpg.00f28680492c52b2242617a383c72cfb.jpg.77600b0c202176eca4802b4b5b34ed57.jpg

 

I reached this point in December 2016. The current configuration has a Vitus amp in place of the SGR. The SGR was a great little amp, but the midbass driver upgrade now meant that the SGR didn't have enough power. 

Edited by Keith_W

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Hey Keith

 

good to see where the system is heading Waiting to see some actual pics  :)

i got some on the PC of how it was when i last visited i can post up :)

 

Just so i understand correctly, are you saying the playback design cant be used as a cd player and dac at the same time????

i am a tad confused with this, maybe i have miss read what you are trying to say...sorry

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You are limited to 2000Hz? Surely that there be a typo Keith.

Edit: Ah, I see the tweeter below the horn now. I don't feel sorry for you any more. :)

Edited by Jake

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This sounds very interesting Keith, I will follow your adventures closely but I must say that I am more pleased to hear that you have grown your music collection so significantly. Please post photos of your music collection.

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Looks to be an interesting evolution. Will there be future pictures of the system in-situ?

Sent from my iPad using Tapatalk

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Hey Keith

 

good to see where the system is heading Waiting to see some actual pics  :)

i got some on the PC of how it was when i last visited i can post up :)

 

Just so i understand correctly, are you saying the playback design cant be used as a cd player and dac at the same time????

i am a tad confused with this, maybe i have miss read what you are trying to say...sorry

 

At the moment the system is not very photogenic. I am waiting for a couple of things: 1) Paul to finish building the subwoofers, 2) Lucas to finish repairing my monoblocks. Until then, there are cables all over the place and a huge subwoofer which I borrowed while I wait for my new subs to arrive. 

 

The Playback Designs can not be used as a transport and a DAC at the same time - that is correct. If you choose the CD mode, it sends the digital output directly to the DAC and disables all the digital outputs. If you choose any one of the digital inputs for the DAC, it disables the transport. 

 

 

You are limited to 2000Hz? Surely that there be a typo Keith.

Edit: Ah, I see the tweeter below the horn now. I don't feel sorry for you any more. :)

 

The tweeters go up to about 40kHz, Jake :)

 

This sounds very interesting Keith, I will follow your adventures closely but I must say that I am more pleased to hear that you have grown your music collection so significantly. Please post photos of your music collection.

 

This is the last time I took a picture of the collection. Since then, I may have added another 500 or more CD's: 

 

original.jpg

 

Looks to be an interesting evolution. Will there be future pictures of the system in-situ?

Sent from my iPad using Tapatalk

 

Yes. Later! In the meantime, here are some older pictures: 

 

original.jpg

 

original.jpg

 

original.jpg

Edited by Keith_W

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Still looks great Keith, looking forward to hearing it in stereo one day mate.

Interested to know the outcome of the sub change.

Edited by Yamaha Man

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I doubt if the sub change will make as much of a difference as the crossover change. The sub change has been in the planning for more than a year. It's been rather slow because of some unanticipated problems with the CNC machinist and cabinet builders whom Paul chose. First one had some personal problems. Second one decided not to go ahead with the project. Third one is actually building the sub. I am hoping to hear back from Paul very soon! 

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theres nothing like a tweeter flame to keep you warm in winter  :)

 

post-104973-0-63497600-1467027681_thumb.

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Or 110W of Class A power. 

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Keith that is a shame regarding the playback. Is it a pain to switch between cd playback and dac though, just wondering if its just a couple of clicks of a remote may not be so bad switching between the 2. Be a shame not to be able to use it at least as an sacd player

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John, firstly I have accepted that it is not possible to take DSD out from the Playback MPS-5 because of Sony enforced copy protection. Each SACD player manufacturer has their own proprietary encryption, and it is not possible to decode DSD output from the MPS-5 to any common form which would be readable by a DSD DAC. Or even my PC. If I want to listen to my SACD's (I mean the DSD layer, and not the RBCD layer), I would first have to rip the SACD into a non-proprietary DSD format using a Playstation 3. 

 

For the time being, I have decided to forego SACD/DSD playback. Even though I own a substantial collection of SACD's, and I have been an SACD evangelist ever since the early days of SNA. 

 

I will have to come up with a solution later. For the time being, implementing the crossover, with an eye towards future DSD playback, is my priority. 

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Thanks Soap. I'm about to put them on the market. 

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Guest Muon

Very nice room, and love those Acapella's and the Cary power amps :love

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makes my what i thought was complex system look like a child's play! impressive!

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I'm confused, don't you still have to do an analag to digital conversion somehow if you want to play from an analog source and this was your issue with DEQX?

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BTW, the graphical diagram is a neat idea. I should give it a go myself!

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Thanks for the comments and likes, guys :) 

 

makes my what i thought was complex system look like a child's play! impressive!

 

It WAS complex, but I am making it more simple now. 

 

BTW the major problem at the moment is how to take measurements once the multi-channel DAC is in place. I have been chatting to Uli about this. The problem arises because: 

 

1. The ADC (for the microphone) has to be clock synchronized to the DAC, 

 

2. Acourate is not able to recognize more than one ASIO device at the same time - meaning that I can not have one ASIO device for the microphone preamp/ADC and another ASIO device for audio output, 

 

3. Any measurement taken MUST include the convolution filter and multi-channel DAC. 

 

The solution is to buy a multi-channel DAC, with phantom power for a microphone input, like the RME Fireface UC. Install the RME, do the measurements, generate the filter, then replace the RME with the NADAC for listening. The downside is that the RME Fireface UC on its own costs $1400. Throw in an Earthworks microphone, and the measurement setup alone will cost close to $2500. OTOH I hear that the RME is a very good DAC and will be quite good as a DAC/amp for my headphones when it's not being used to take measurements! 

 

 

I'm confused, don't you still have to do an analag to digital conversion somehow if you want to play from an analog source and this was your issue with DEQX?

 

Yes that's right. I have decided that I am no longer going to use an analog source. If I did, I would probably go for a pro audio ADC. 

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sorry but what measurements do you need to take? you mean for DRC?

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Yes that's right. I have decided that I am no longer going to use an analog source. If I did, I would probably go for a pro audio ADC.

OK, getting rid of analog sources is something I agree with but that means your reason for ditching DEQX in the first place no longer applies ;)

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