[TomW16]

I have a couple of questions that might help me decide to build a pair of ncore amplifiers:

1.  I recently read a thread about Class II grounding and how it is preferred to NOT ground the chassis with the ncores.  I do a little bit of wood working and it wouldn't be too hard for me to create a wooden chassis for the ncore modules and power supplies.  Is there any reason to avoid a wooden chassis? 

2.  I'm currently working out a grounding issue with my home theater system, which I discovered by inserting some Parts Express 6 db attenuators to the RCA cables (which created a hum).  Without the attenuators, the system is silent.  I am thinking that I can avoid the attenuators if I can increase the level of my main amp by 6 db, which most XLR connections would typically provide.  Is there a 6 db increase by using balanced XLR cables versus single ended cables with an adapter with the ncore amps?

Thank you in advance for your valued input.

Kind regards,
Tom

[Julf]

1.  I recently read a thread about Class II grounding and how it is preferred to NOT ground the chassis with the ncores.

The class I vs class II is purely a safety issue. It's just that if you don't connect the chassis to mains safety earth ("grounding" seems to mean different things to different people), you will have to follow class II rules for safety reasons.

I do a little bit of wood working and it wouldn't be too hard for me to create a wooden chassis for the ncore modules and power supplies.  Is there any reason to avoid a wooden chassis?

No, not really, as long as you ensure sufficient ventilation (a metal chassis helps radiate heat, a wooden one doesn't).

2.  I'm currently working out a grounding issue with my home theater system, which I discovered by inserting some Parts Express 6 db attenuators to the RCA cables (which created a hum).  Without the attenuators, the system is silent.  I am thinking that I can avoid the attenuators if I can increase the level of my main amp by 6 db, which most XLR connections would typically provide.  Is there a 6 db increase by using balanced XLR cables versus single ended cables with an adapter with the ncore amps?

All depends on your source. The hypex input is fully differential, so it won't care if you feed it a balanced or unbalanced signal - the gain will be exactly the same. On some source/preamp output stages the balanced output gives double the unbalanced voltage (so provides a 6 dB increase).

[TomW16]

Thank you for the feedback Julf.  I think that I'm comfortable with the safety aspects specified by Class II (insulated chassis, which wood naturally provides; of course it burns though) but I was wondering if there were any reasons such as RFI to use metal rather than wood?  Your point about heat radiation is a good one and I would ensure that there is adequate ventilation.

My objective is to use an Oppo BDP-105 player as a preamp, which works well but my main speakers are not very efficient and require a 3.5 db boost to the speaker trim levels within the Oppo unit, which causes distortion (the other speakers are maxed out with full reduction).  I tried to use in-line attenuators for the other channels but that is when I hit the grounding issue and hum.

The Oppo unit specifies 2.1 Vrms through the RCA jacks and 4.2 Vrms through the XLR jacks.  I am wondering if the higher output through the XLR would increase the main speaker levels so that in-line attenuators would not be required for the other channels.

Thanks.
Tom

[Julf]

I was wondering if there were any reasons such as RFI to use metal rather than wood

There will of course be people who disagree, but the Hypex modules are pretty good at resisting RFI (and don't actually radiate that much either), and a thin piece of metal won't make much of a difference anyway.

The Oppo unit specifies 2.1 Vrms through the RCA jacks and 4.2 Vrms through the XLR jacks.  I am wondering if the higher output through the XLR would increase the main speaker levels so that in-line attenuators would not be required for the other channels.

Yes, seems the Oppo is one of the designs that provides double the voltage (so +6 dB) on the XLR, so that sounds like the way to go - except you need to watch out, as 4.2V will drive a nc400 to overload if you turn volume all the way up.

[TomW16]

Thank you for the feedback Julf.  Now I just need to sell a few components and order a ncore kit.

Tom