Hi,

Moderator: If I placed this in the wrong subforum, please move as appropriate.

I have recently built a 6-channel amp based on UCD180HG and UCD400ST modules using Opus DACs, arduino controlled, with a nanoDigi from minidsp in the samme chassis. The chassis is very crammed, and I want to take some learnings from this project, improve the things I wasn't entirely happy with and build a new one in a larger chassis. Initially I want to go for 8 channel, but catering for an extra set of channels is the goal, so I just received a huge chassis from modushop. :)

What I aim for is in terms of VRMS at the speaker terminals:

A. Woofer channels: 40VRMS (2VMRS + 26db: Opus + unmodified UCD gives this).
B. Midrange/tweeter channels: 12.6VRMS (2VRMS + 13db: Opus + gain-adjusted UCD gives this)

If I were to bypass the differential input stage of the UCD modules, I would get 4,5x voltage gain. This means that the max voltage into the UCD stage would have to be:

A. Woofer channels: 40VRMS/4,5 = 8,8 VRMS
B. Midrange/tweeter channels: 2,8 VRMS

Question 1: What would give the best sound quality of the two options below:

1. Opus DAC + UCD HG+HXR (gain adjusted where necessary)
2. Buffolo DAC+IVY into UCD ST where I bypass the differential input buffer completely and go directly to the UCD.

Question 2: Can the IVY provide 8,8VRMS output to cater for the woofer channels?

Question 3: Can the IVY work with an input impedance of 10K (cold and hot), i.e. can it drive the UCD part without any additional buffer? Is it a sound proposal?

Question 4: If I go for alternative 1 above (Opus + high grade UCDs), there are two DC-offset caps in the path - one at the output from the Opus DAC, and one after the differential buffer stage of the UCD. Should I bypass any of those? In that case, which ones should be bypassed - Opus or Hypex?

Question 5: If I do want to go with an IVY-setup - is it silly to get Hypex's modules in the first place, since they have extra circuitry that I will bypass? Is there a simpler class D module that fits better with this configuration and provides as good sound quality?

Question 6: When is the multichannel IVY board coming? Will it be affordable? :)

Question 7: Any other ideas, inputs, things I should know? :)

Martin

@Corpius

Thanks - but the Ncores are quite expensive, especially for an 8 channel amp.

Any inputs on the other questions?