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hisense  
#1 Posted : Saturday, March 5, 2011 8:35:57 AM(UTC)
hisense

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Quick query re using 3 Buff 2 with a PC based active crossover setup,

Will there be any sync / timing / phase issues to be aware of using 3 seperate AES feeds to 3 seperate Buff2 for bass / mid / hf per channel? I am guessing any variation will be negligable due to the high frequency of the re sampling although the clocks / 3 boards will not be operating in sync.

Also presuming Volumite would control 3 x Buff2 boards with the I2c buss linked in parallel?

Current setup - Dual Mono Buff2 / trident with dual Legato2, it sounds fantastic. Would like to thank Russ and Brian for designing and making availble these superb kits and the excellent suppport and service!

Cheers,

Luke

Russ White  
#2 Posted : Saturday, March 5, 2011 8:42:15 PM(UTC)
Russ White

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Thanks for the kind words.

No, you should not have any timing issues.

At 100Mhz it will not matter if they are in sync as long as the input signal is. :)

No you cannot use one volumite with 3 Buf-II, but you can you one pot to control three volumites. :)

Sounds like a great project!

Edited by user Saturday, March 5, 2011 8:51:38 PM(UTC)  | Reason: Not specified

glt  
#3 Posted : Saturday, March 5, 2011 9:41:45 PM(UTC)
glt

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Russ White wrote:
...
No you cannot use one volumite with 3 Buf-II, but you can you one pot to control three volumites. :)
....



Clever! that is an advantage of using a pot instead of a rotary encoder
hisense  
#4 Posted : Sunday, March 6, 2011 5:42:55 AM(UTC)
hisense

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Thanks for the info Russ, looking forward to getting it up and running.

The plan is to use the PC for FIR x over filters and driver EQ / DRC output through a Lynx AES16 multi channel AES card > Buff2 dac's > ATC discrete tri amp pack > ATC SCM150SL

Filters generetaed using a programme called acourate - very comprehensive, worth a look if your interested in PC based x over or DRC.
rxetera  
#5 Posted : Tuesday, March 8, 2011 3:09:07 PM(UTC)
rxetera

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Looking forward to seeing updates on your setup as I'm also thinking about going this route! A few questions:

1) I'm assuming you'll be building your own AES3 to SPDIF converters? I wish someone would create a board that takes all the Lynx channels and converts them to SPDIF (hint ;-)

2) What are you planning to use for software; brutefir, cmp, xxhighend, etc?

3) Are you also planning on doing any DRC in addition to X-overs?

4) Any plans to build up your system in stages and document where the biggest gains in SQL are?

As you can see, I've been thinking a lot on this subject and I'm planning on doing all of the above. Only issue with me is that my current speakers are Mirage Omni-polars which may pose some problems for DRC, but I'm looking forward to giving it a try.

Best of luck!
hisense  
#6 Posted : Wednesday, March 9, 2011 12:22:08 PM(UTC)
hisense

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Hi,
Yes will post updates as i progress;

Some info: currently using the dual mono Buf2 to feed the ATC discrete active x over boards and will have to get my DIY PC / DAC based solution well sorted before i take the plunge and go to the amps direct. The two major concerns are:

Reliable volume control that doesnt compromise the signal too much; Buf2 hardware based seems to be the solution although it doesnt allow different levels to be set and fixed for each dac for bass/mid/hf. Potentially look at altering the resistance seen by mid & hf volumite if a master pot is used to control 3 volumite boards.

PC crash causing VST host / VST convolver to send digital noise to mid and hf drivers damaging them! My Lynx card has on two ocasions had a conflict with the system and sent digital noise out!

Yes have made a simple AES3 to SPDIF using a Lundahl LL1572 1:1 pulse transformer and T pad network as per rane AES note - works well. Bit crude and would much rather a well made TPA multi channel solution....

I use foobar for playback via ASIO use the hardware loopback funtion of the lynx card and then use Plogue bidule with ASIO in / out as the VST host, running VST convolver for the individual x over filters. Again works well and multi core support. There are other hosts like Reaper, Console etc I have tested the PC based x over using a pro multi channel sound card on a PA rig and it works very well.

Once i have a robust x over solution up and running and have proven it at least equals the analogue active x over boards i will then convolve the x over filters with the driver linearisation / eq filters and finally the room correction. TBH i think the biggest gains of the pc based setup is the Linear phase filters and delay if you need it. The ATC x over boards allready have inter band phase adjustement so it may be a close call, bit of an experiment really!

Good luck with your project
LeonvB  
#7 Posted : Wednesday, March 9, 2011 3:57:33 PM(UTC)
LeonvB

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Quote:
Reliable volume control that doesnt compromise the signal too much; Buf2 hardware based seems to be the solution although it doesnt allow different levels to be set and fixed for each dac for bass/mid/hf. Potentially look at altering the resistance seen by mid & hf volumite if a master pot is used to control 3 volumite boards.

Build a controller with 3 I2C busses. Then simply set the volume registers on the 3 DACs individually to balance low/mid/hi, and left/right. It's all software. You could look at glt's webpages for a place to start.
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