Mauro's "Myreference Rev.C" building queries and guide.

[linuxguru]

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is anyone seriously intrested?
i ask because you must understand that such a chasis with this level of finish is not cheap(especially considering those huge sinks)

Also if this chasis is built i dont know the technicalities oh how you would place your PCB wrt to the heatsink
is it possible? - i mean placing your PCB;s after the chasis is built with the sinks
do you have to mount the sinks ON the PCB , next to it - i dont know

The heatsinks can be smaller - half the length, and half the height and it will be still be fine. Several of the stock cast aluminium heatsinks from Amar Radio Corp. will work, but they will have to be drilled and tapped precisely.

The chipamp needs to be mounted to the heatsink with a bolt and nut - there needs to be a drilled hole (maybe 3 mm dia.) on the heatsink at the appropriate location. The mounting bolt can be a nylon screw and nut, only slight pressure is required against the heatsink.

The PCB sits almost flush against the heatsink, and is mounted to the floor of the cabinet using 4 standoffs - again, 4 x 3 mm holes need to be drilled in the floor of the cabinet for each PCB. Dimensions of the PCB are approx. 104mm x 90mm - I am enclosing the layout for reference.

Edit: The alternative is to design an aluminium face-plate for the Dexa chassis, similar to the faceplate on the Modu website, but even simpler - it only needs holes for the switch, 3 LED(s), and 4 mounting holes. Maybe a volume control with knob.

 

[magma]

S

Maybe Magma should replicate the Nova finish and create a scare in the market

Cheers

show me show me!

 

[magma]

The heatsinks can be smaller - half the length, and half the height and it will be still be fine. Several of the stock cast aluminium heatsinks from Amar Radio Corp. will work, but they will have to be drilled and tapped precisely.

The chipamp needs to be mounted to the heatsink with a bolt and nut - there needs to be a drilled hole (maybe 3 mm dia.) on the heatsink at the appropriate location. The mounting bolt can be a nylon screw and nut, only slight pressure is required against the heatsink.

The PCB sits almost flush against the heatsink, and is mounted to the floor of the cabinet using 4 standoffs - again, 4 x 3 mm holes need to be drilled in the floor of the cabinet for each PCB. Dimensions of the PCB are approx. 104mm x 90mm - I am enclosing the layout for reference.

.

linux
the heat sinks that i have access to are probably better than amar radio corp ( if you say they are CAST)
the heatsinks i have access to are pure solid aluminium extrusions

Also
PCB mounting on the base/floor with 4 standoffs is not difficult and can be done easily as long as i have a sample PCB and everyone is using the same

i still cant understand the part of how the mounting of heatsink is done wrt to the PCB
the pics dont exactly show that
and i dont understand
"The chipamp needs to be mounted to the heatsink with a bolt and nut - there needs to be a drilled hole (maybe 3 mm dia.) on the heatsink at the appropriate location. The mounting bolt can be a nylon screw and nut, only slight pressure is required against the heatsink"

you will probably have to explain to me as if im a two yr old!

 

[magma]

There are these large caps at the signal input's. Anyone know what they are for?

hmm this pic shows the mounting
theres a gold colored screw used for the mounting i see
what i cant figure out is what that black thing is around the golden nut

need some details on that

 

[gobble]

hmm this pic shows the mounting
theres a gold colored screw used for the mounting i see
what i cant figure out is what that black thing is around the golden nut

need some details on that

That black thingie with the "golden" nuts hanging around is ....

1. Some kind electronic device like a power regulator
2. Some kind of unmentionable hyeah:
3. An object of fantasy for female "audiophiles"
4. None of the above

Edit: How do I convert a single reply post into a Poll?

 

[linuxguru]

hmm this pic shows the mounting
theres a gold colored screw used for the mounting i see
what i cant figure out is what that black thing is around the golden nut

The heatsink is actually mounted to the rear and front panels using tapped holes and L-brackets respectively. The sheet-metal floor is also bolted to the heatsink using tapped holes in the heatsink. The PCBs are mounted to the sheet-metal floor, with the LM3886 IC being flush against the heatsink - that is the black, rectangular device in the photo. A single bolt,washer and nut are used to keep the LM3886 IC flush against the heatsink - that is the gold-coloured screw visible in the photo.

The weight of the heatsink is borne by the front and rear panels. The sheet-metal floor keeps the heatsinks, front and rear panels aligned firmly. The LM3886 IC on the PCB does not bear the weight of the heatsink, but only touches it lightly. The golden screw applies enough pressure on the LM3886 IC to keep it flush against the heatsink to ensure good heat transfer. There may be some insulating material (white in the picture) between the LM3886 IC and the heatsink. This is not required for the LM3886TF with the fully-isolated plastic package.

 

[linuxguru]

That black thingie with the "golden" nuts hanging around is ....

...the LM3886 chip-amp in a TO-220/11-pin package.

 

[gobble]

...the LM3886 chip-amp in a TO-220/11-pin package.

Wha?!!! No wonder there is no silicone "rubber" heat insulation or "sheath" around it ... hyeah:

Spoilsport ...

 

[magma]

hmmm this flush mounting makes it almost impossible for me to make this kind of chasis WITHOUT a fully assembled sample pcb board

In this case it is wise that members use their own sinks and mount it on the PCB as shown

unless there are enough members wanting the SAME chasis and can spare a board to send me as sample ( not fully assembled but at least with the IC done)

 

[linuxguru]

hmmm this flush mounting makes it almost impossible for me to make this kind of chasis WITHOUT a fully assembled sample pcb board

The version 1.3 PCB is not yet fabricated - I'm just waiting for a second quote before closing. Allow for 14 days for fabrication after closure, + a couple of days to assemble and test the first boards. The earliest time for a sample board is end-Aug/early-Sep.

However, I do have assembled Twisted Pear version 1.2 board(s) - which is smaller in size than the Version 1.3 board whose layout I posted earlier. The height of the LM3886 above the board will be identical.

The only changes I expect are in the location of the drill holes for the 4 standoffs for the PCBs.

Everybody in the current Group Buy will be using the version 1.3 boards (yet to be fabricated). Only Keith Correa and I have the version 1.2 boards from the DIYaudio group buy, for which alternate cabinets can be found.

Depending on the pricing, there's potentially interest for 10 to 20 identical cabinets (based on the interest for 20 to 40 version 1.3 monoblocks). I'd be interested in 2 cabinets at least.

 

[gobble]

hmmm this flush mounting makes it almost impossible for me to make this kind of chasis WITHOUT a fully assembled sample pcb board

In this case it is wise that members use their own sinks and mount it on the PCB as shown

unless there are enough members wanting the SAME chasis and can spare a board to send me as sample ( not fully assembled but at least with the IC done)

I think you only need to provide a small square or rectangular cut thru "peep hole" to attach the chip directly to the heatsink. The rest of the heatsink can have its back to the chassis wall with screw holes to attach it firmly along the length at various points.

What do you think of this scheme by the scheming devil?

Cheers

 

[captrajesh]

capt rajesh,saikat and a few others have asked whether i can build an amp chasis

is anyone seriously intrested?

unless there are enough members wanting the SAME chasis and can spare a board to send me as sample ( not fully assembled but at least with the IC done)

I'm definitely interested. I urge all interested members to post their answers so as to enable Magma to work out the numbers.

you must understand that such a chasis with this level of finish is not cheap(especially considering those huge sinks)

Such a big heat sink may not be required IMHO.

 

[GeorgeO]

I'm also interested in 2 enclosures

 

[Hiten]

Regarding amp enclosure group buy one solution can be to make a universal type of enclosure so as to fit different sizes of components like heat sink, transformer or for that matter different amp also. Rear panel can me made detachable so as DIYers can arrange connectors, power in as per their choice.

 

[captrajesh]

Regarding amp enclosure group buy one solution can be to make a universal type of enclosure so as to fit different sizes of components like heat sink, transformer or for that matter different amp also. Rear panel can me made detachable so as DIYers can arrange connectors, power in as per their choice.

Trust me, unless you standardise, you are going to incur more. Let everything be standardised. OK, things like connectors are of standard size so that can be given as an option. I mean, if someone wants a gold plated connector, let him not opt for it and source it locally.

 

[Hiten]

Trust me, unless you standardise, you are going to incur more. Let everything be standardised. OK, things like connectors are of standard size so that can be given as an option. I mean, if someone wants a gold plated connector, let him not opt for it and source it locally.

That's what I mean a universal standardised enclosure. Detachable rear panel means one can take it to any shop to cut connectors power in holes etc.

 

[gobble]

Hiten is right.

PCB holes can be drilled by the DIY'er. Else like the image shown, make a 2x2 grid of 3mm threaded holes at various places on the enclosure floor and if one gets lucky future PCB dimensions might fit neatly without additional drilling.

9.8mm holes for RCA and volume pot and switch selector should suffice for a generic chassis.

Will need to standardize on the size of IEC panel socket as well - one of the RF filtering IEC sockets I possess does not fit into the ordinary cut out dimensions.

I will take 3 enclosures for my other projects as well.

Cheers

 

[captrajesh]

Even cutting holes with precision & with quality finish is not easy & would cost atleast Rs. 100/- only for labour. Add to that the cost of time & money in scouting for a right guy with right eqpt & it would be substantial IMHO

 

[Hiten]

Even cutting holes with precision & with quality finish is not easy & would cost atleast Rs. 100/- only for labour. Add to that the cost of time & money in scouting for a right guy with right eqpt & it would be substantial IMHO

I understand captain. So another solution would be ~ major number of enclosure made would be fully finished and few numbers would have plain rear panel. Best of both the world

 

[stereorules]

I would be interested in one too...Tho' would like to have a rough estimate of the cost also..