[rodentmacbeastie]

I am building a balanced Aikido, Opus DAC head/pre amp. While I am awaiting the arrival of parts, my scope has got more interesting(and expensive). Started out with the plan for a SE Aikido/Opus. Now I am building my ultimate system from start to finish, only keeping the HD650. It will go like this:

Two chassis. One for the BOX'O'GOODIES, second for the power supplies.

BOX'O'GOODIES:
-HTPC with lots of storage for all PCM playback and DVD player. ESI Julia sound card modded to put I2S out to the Opus.
-Pioneer DVD player(gutted to get the spinner and SACD board) to send a pure DSD signal to the Opus. Also will be a top loader. I am really hoping this turns out as I expect.
-Opus DAC with Jacob's Ladder volume control, I2S switcher, S/PDIF, Uber controller.
-Balanced Aikido linestage/headamp with 6CG7/6H30 tubes(maybe 24v version, not sure yet)

PS chassis:
-separate PS for the HTPC, Aikido, Opus with a power conditioner built in.

Active speakers:
-two Hypex UcD180HG amp and dedicated SMPS for each tower.
-four 4" full range drivers in an open baffle semi-line array per tower
-two 6.5" bass drivers for each tower in a sealed cabinet
-Marchand XM44 48db/oct active balanced Xovers cut off at 200-500Hz(not sure yet)


Deciding on whether or not to place the amps/Xovers in the speakers or in mono-blocks next to the BOX'O'GOODIES. I think it would sound better with a balanced signal to the speakers with amps built in but it would be easier and cheaper to do mono-blocks close to the power conditioner. Cleaner looking too, only one power cord from the wall and two sets of speaker cable. Also deciding on a 7" touchscreen or just a monitor and mouse. I want a mouse and keyboard anyway and for the price of the touchscreen I can buy them and a 22" monitor and no headaches.

Any ideas would be appreciated.

 

[error401]

As long as you're aware of the delays in getting the WM8741 chip, it sounds like a pretty sweet system you're cooking up. It will probably be 4 months or more before they're available in quantity. Until it's available, you won't be able to build up your DAC (or you'll have to forfeit DSD). AD1955 and DSD1794A are both readily available and support DSD, but they're both considerably more difficult to use than WM8741 (both are current-out, and AD1955 requires a microcontroller). I'm not aware of any existing designs based around either chip that you could use instead (I'm working on an AD1955 DAC myself, but it's nowhere near complete yet).

I'm also not sure about how you've split up the cases. Inside a PC isn't exactly the best place for low-level analog signals (though it's probably not that bad either). Then you toss a noisy SMPS in the same case with your inefficient and clean linear supplies. Might not be a problem, but I would probably choose to put the HTPC in one case and the analog gear in another. I'd rather have transformers near my analog gear than high speed digital electronics.

 

[rodentmacbeastie]

Quote:

Originally Posted by error401 /img/forum/go_quote.gif As long as you're aware of the delays in getting the WM8741 chip, it sounds like a pretty sweet system you're cooking up. It will probably be 4 months or more before they're available in quantity. Until it's available, you won't be able to build up your DAC (or you'll have to forfeit DSD). AD1955 and DSD1794A are both readily available and support DSD, but they're both considerably more difficult to use than WM8741 (both are current-out, and AD1955 requires a microcontroller). I'm not aware of any existing designs based around either chip that you could use instead (I'm working on an AD1955 DAC myself, but it's nowhere near complete yet). I'm also not sure about how you've split up the cases. Inside a PC isn't exactly the best place for low-level analog signals (though it's probably not that bad either). Then you toss a noisy SMPS in the same case with your inefficient and clean linear supplies. Might not be a problem, but I would probably choose to put the HTPC in one case and the analog gear in another. I'd rather have transformers near my analog gear than high speed digital electronics.

I am not going to start to learn how to design a DAC, the Opus is perfect for me so I will wait. As for the chassis, each PS will have it's own shielded compartment. The PC ps will be remote too. Same goes for the components, separate shielded areas. There is some crazy paper that shields RFI and EMI that I will try. If that does not impress me, copper plates will do. The reason I want to put the PC close to the DAC is to keep the I2S lines short(under 4"). The lines will run from the soundcard through a shielded divider to the DAC. This should suffice, yes?

 

[fran]

FYI - broskie has a new 24V aikido board with provision for use as both headphone amp and regular preamp. I have ordered one, he only got 20 made. I haven't read the whole blurb on it, but I believe it has a discrete output buffer section for the cans.

Fran

 

[rodentmacbeastie]

Quote:

Originally Posted by fran /img/forum/go_quote.gif FYI - broskie has a new 24V aikido board with provision for use as both headphone amp and regular preamp. I have ordered one, he only got 20 made. I haven't read the whole blurb on it, but I believe it has a discrete output buffer section for the cans. Fran

I saw that he had... My concern is the sound of low voltage tubes. If they sound good, I am in. Otherwise, I will likely buy the 24V and use high voltage tubes. My other concern with the 24V is the limited availability and selection of the 6GM8.

 

[threEchelon]

Quote:

Originally Posted by rodentmacbeastie /img/forum/go_quote.gif I am not going to start to learn how to design a DAC, the Opus is perfect for me so I will wait. As for the chassis, each PS will have it's own shielded compartment. The PC ps will be remote too. Same goes for the components, separate shielded areas. There is some crazy paper that shields RFI and EMI that I will try. If that does not impress me, copper plates will do. The reason I want to put the PC close to the DAC is to keep the I2S lines short(under 4"). The lines will run from the soundcard through a shielded divider to the DAC. This should suffice, yes?

I believe you can run IS2 longer than 4" without any problems. I believe the recommended length is 1.5ft or less.

 

[OverlordXenu]

If you have the cash, I'd go for an HTPC running off of (a) compact flash card(s), to try to make it as silent as possible, then put together a server with lots of storage to stream all your music, movies, tv shows, act as a DVR, etc.

Having your own home server is really, great. I have around 5 (maybe more), they are pretty much just old computers (I've upgraded over the years) stuck into the network running linux or Server 2003, for various tasks...like a general file server, an Exchange server (push email for my phone), you get the idea.

Also, I'd forgo the DVD player and just spend $300 on a blu-ray/HD DVD combo drive for the HTPC.

 

[rodentmacbeastie]

Quote:

Originally Posted by OverlordXenu /img/forum/go_quote.gif If you have the cash, I'd go for an HTPC running off of (a) compact flash card(s), to try to make it as silent as possible, then put together a server with lots of storage to stream all your music, movies, tv shows, act as a DVR, etc. Having your own home server is really, great. I have around 5 (maybe more), they are pretty much just old computers (I've upgraded over the years) stuck into the network running linux or Server 2003, for various tasks...like a general file server, an Exchange server (push email for my phone), you get the idea. Also, I'd forgo the DVD player and just spend $300 on a blu-ray/HD DVD combo drive for the HTPC.

But the point if the player is to get SACD out to the DAC. If you know of a way to read and decode SACD on your PC, many will want to know how.

 

[00940]

Quote:

Originally Posted by threEchelon /img/forum/go_quote.gif I believe you can run IS2 longer than 4" without any problems. I believe the recommended length is 1.5ft or less.

Without proper buffering, 1.5ft seems a bit long. IIRC, 20cm is often given as max length.

 

[threEchelon]

Shorter definitely doesn't hurt, but if you look around, you'll find people who've successfully done runs over 20cm. Steve Nugent sells one of his I2S products with a 1ft cable and IIRC, he was the one to make the 1.5ft recommendation.

 

[00940]

Quote:

Originally Posted by threEchelon /img/forum/go_quote.gif Shorter definitely doesn't hurt, but if you look around, you'll find people who've successfully done runs over 20cm. Steve Nugent sells one of his I2S products with a 1ft cable and IIRC, he was the one to make the 1.5ft recommendation.

Well, you can definitely run (way over) 1.5ft but you need to be careful. For 15 or 20cm, there's no big deal, at 45cm, some care is needed (I don't doubt Steve Nugent is doing it properly). It's not so much the length I object but the "without any problems".

 

[luvdunhill]

Quote:

Originally Posted by threEchelon /img/forum/go_quote.gif I believe you can run IS2 longer than 4" without any problems. I believe the recommended length is 1.5ft or less.

I'd recommend adding a buffer. Use something like a 74HC125 and 2N4401 transistors, even at 4".

 

[OverlordXenu]

Quote:

Originally Posted by rodentmacbeastie /img/forum/go_quote.gif But the point if the player is to get SACD out to the DAC. If you know of a way to read and decode SACD on your PC, many will want to know how.

Oh, I wasn't reading carefully. I thought he just wanted it to play DVD's.

 

[rodentmacbeastie]

Quote:

Originally Posted by OverlordXenu /img/forum/go_quote.gif Oh, I wasn't reading carefully. I thought he just wanted it to play DVD's.

No worries, but I do love the sound of a good SACD and I have a few. Since I have the player, it won't cost anything to do this unless I fry it in the mod process.

 

[rodentmacbeastie]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif I'd recommend adding a buffer. Use something like a 74HC125 and 2N4401 transistors, even at 4".

Interesting. Many players have I2S signal paths longer than 4". I should be able to keep the lines to 2" since I am building the HTPC and the DAC in the same box. I can't emphasize enough how I would love to keep as many transistors and SS components out of the equation. This is the reason I want to go this way in the first place, to eliminate the I2S to S/PDIF conversion. The less stuff in the signal line the better IMHO. Since the I2S signal on the Julia board runs at least 1", 2" should be more than OK.