[Build] CAPI Summing Mixer ~ SumBus ACA ~ Official Support Thread

[JW]

Oh right. I was thinking 312 land, where it's 1:2.

Thanks Jeff. Does anyone have an appropriate schematic for this? I'm assuming some kind of THAT chip, ultra "transparent." Are transformers afterward necessary if you consider I'd be switching between balanced and unbalanced speaker amps?

 

[jsteiger]

Oh right. I was thinking 312 land, where it's 1:2.

Thanks Jeff. Does anyone have an appropriate schematic for this? I'm assuming some kind of THAT chip, ultra "transparent." Are transformers afterward necessary if you consider I'd be switching between balanced and unbalanced speaker amps?

You can use an INA137 as a -6dB receiver, some sort of 10k-ish level control to DRV134s. Balanced in, balanced out +28dBu of headroom.

 

[JW]

Jeff, do you happen to have a schematic or know what schematic I should refer to for that INA137/DRV134 implementation?

 

[sadmonkeysound]

I finally finished my sumbus 32x4 after many delays due to holidays and illness, and it's absolutely killer.

Unfortunately, before I could confirm that it's absolutely killer, I spent a few hours chasing ghosts only to remember a thread, and then confirming that I'm having the same switch mode PSU issue as mentioned in the VPR rack thread here:
https://groupdiy.com/threads/build-...ck-official-support-thread.67873/post-1068598
With all 32 channels populated, it blinks more or less forever. I was able to verify that things work perfectly with an older CAPI SMPSU from a VPR rack. A newer, as yet unbuilt VPR rack appears to have come with the new PSU, which also exhibits the problem. The "workaround" of letting the PSU stabilize before connecting the multipin to the mixer appears to "resolve" things, although that's not a long term workaround for me given the way my installation is done. Any update on when revised/reverted PSUs might be available?

Thanks!

 

[museric]

Hi Jeff!
What is the depth measurement of the finished SumBus32? Is it anywhere around 18 inches, or less than that?
(I've got a homemade rack in a very tightly packed little project studio, and I spec'd the construction off of other summing equipment - I'm now reconsidering that... )

BTW - I just finished up my third kit, the second of two BT50's and I have to say I'm blown away.

 

[jsteiger]

Hi Jeff!
What is the depth measurement of the finished SumBus32? Is it anywhere around 18 inches, or less than that?
(I've got a homemade rack in a very tightly packed little project studio, and I spec'd the construction off of other summing equipment - I'm now reconsidering that... )

BTW - I just finished up my third kit, the second of two BT50's and I have to say I'm blown away.

They are just over 14" not including the XLR connectors.

 

[EMUSP1200]

Has anyone tried or thought of modding the sumbus with direct outs on the channels?

 

[grievousangel]

Anyone created a signal flow chart or (simplified schematic) for the SumBus32? I have a 16x4 version I am finally finishing up!

IMHO ... support documentation on the CAPI kits could be expanded some! It's all great until you have a problem. Determining signal flow can be 'trick', and takes much time. CAPI has great products, i.e., appearance, quality and sound!

Later, Billy

 

[grievousangel]

I finally completed and tested 8 of 16 Input Channels on my SumBus32 16x4 project. I getting ready to start the last 8 of the 16 Input Channels.

I have question about the 4k99 MF substitute (R21, R22, R34, R35, R45) for the 4k42 MF. My 'pink bag' came with (8) 4k99 to replace the original (8) 4k42. The SumBus2 Rev A BOM calls for (6) per PCB (2 channels), therefore (24) 4k99 are required to build my remaining 8 channels. I can't remember exactly how I resolved the qty issue for my 1-8 channels . . .

Am I missing 'something' or missing parts?

Later, Billy