AMB Laboratories DIY Audio

[tention]

I'm planning to build the M³ + σ11 in a single aluminium chassis. Is there anything I should take note of? Can I put everything (boards, transformer) next to each other?

Wanted to keep the chassis small, and found one with the following measurement:
Interior measurement: 6.85"W X 11.41"D X 2.12"H

Do you think it will fit?

Thanks

[amb]

There are several issues to consider, but the most important one is to keep the power transformer and all AC wiring as far away from the amp board and input wiring as possible.

[DrJones]

There are several issues to consider, but the most important one is to keep the power transformer and all AC wiring as far away from the amp board and input wiring as possible.

I have quite a similar issue. I did purchase a Hifi 2000 case, when I found one forum member to use same case to M3 + Sigma 11 power suply. I did not do my own calculations and found out that components does not fit in perfectly. However, they fit in, even when volume potentiometer is mounted to pcb. The case is 9cm height (almost 4") so I can put the Sigma 11 PCB partly on top of M3 board an transformer to one corner and RCA:s to another corner. When I look the pic about my initial layout inside box, I think that I should chance the power switch and output plug places so I dont need to put AC wires under (or on top of) M3 board, luckily that can be done because I did not have drills big enough to drill hole for the plug =)

Can you found any problems about my mounting? Or some other advice. Ofcourse I need to take care of isolation between PCB:s. If I found some humming, first thing to do is put transformer to closed metal box inside case?

[amb]

While it's good practice to mount the transformer as far away as possible from the board, in this case it's clear that there isn't enough room to find an optimum solution. Your transformer is mounted on the input side of the M³ board, which is more susceptible to induced hum. It's too bad you couldn't flip it around and put the σ11 and transformer on the output side. Such is the constraint when you want the volume knob to be in the middle of the panel while there is not much room in the case to work with.

There is no intrinsic problem with the two slightly overlapping boards, I would also keep the σ11's D1-D2 rectifiers from being too close to the amp board or input wiring. How will you be securing the boards? You shouldn't drill into the M³ board to mount spacers for the σ11, because there are circuit traces there.

Assuming you're not willing to change to a larger case, I would recommend putting the power transformer into its own box. At least that will avoid the biggest problem in this layout.

[DrJones]

How will you be securing the boards? You shouldn't drill into the M³ board to mount spacers for the σ11, because there are circuit traces there.

Assuming you're not willing to change to a larger case, I would recommend putting the power transformer into its own box. At least that will avoid the biggest problem in this layout.

Thanks for advice!

I was planning to use extra hole (extra hole for my setup) in Sigma board inside of heat sink, then I have three mounting points. I was not ment to drill through M3 PCB =) Three mounting points may be just enough, but it should not be a problem to add some holder, made for plastic pen or something, under one corner of the Sigma board and use a 'hot glue' or some clips to attach it to pcb.

You made a right assumption, I'm not changing the case. I will put the transformer to it's own metal box, and if in the end I found some humming, the last option is to move power supply to separate case. I really dont want to do that, when I'm actually planning to put Gamma 1 to the same main box. I will get back to the Gamma case later, but for now, my plan is to build Gamma to its own hammond box, and use the main case rear panel as Gammas rear panel, so that the Gamma will be completely inside of its own metal box inside of the main case. Most likely I change gamma outputs to RCA, mounted rear of the main case, but I'm still considering to wire gamma output directly to the M3 input (disadvantages known, but I most likely will use my setup only: USB in -> headphones out, at office and thats it, So I really don't need line level analog inputs and outputs at all .

[mikeg88]

I'm actually planning to put Gamma 1 to the same main box. I will get back to the Gamma case later, but for now, my plan is to build Gamma to its own hammond box, and use the main case rear panel as Gammas rear panel, so that the Gamma will be completely inside of its own metal box inside of the main case. Most likely I change gamma outputs to RCA, mounted rear of the main case, but I'm still considering to wire gamma output directly to the M3 input (disadvantages known, but I most likely will use my setup only: USB in -> headphones out, at office and thats it, So I really don't need line level analog inputs and outputs at all .

My build is very similar to what you describe, except the DAC is a Gamma 2. You might want to look at the build photos in this thread: post-pics-of-your-builds-t44-570.html#p16938

The case is from Par-Metal. OliverD did this configuration before I did, I just copied him. If you have questions, I'm happy to help.