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AMB reference β24 power amplifier .fpd files

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Re: AMB reference β24 power amplifier .fpd files

Postby RainfallSky » October 10th, 2019, 3:32 am

Somehow I forgot AMB reference build FPE files had mounting holes with a unified fine threads.
ModuShop contacted me they can't do them, only M3, M4, and M5.
So I made a hasty reply. Heatsink now have M3 thread and mounting holes.
Front panel mounting holes for front subpanel M5 thread and holes.
And other mounting holes for front and back panels now have M4 thread.
Now that I think about it maybe I should have made M3 threads for support brackets but too late. )
So.. now I would need to adapt FPE files for subpanels according to new sizes.
I plan to use DIN 912 stainless bolts (but will accept for consideration other options).
Overall bolts will look a bit bigger then in reference build and front subpanel will look a bitmore brute.
Mr Ti, what bolts did you use for front and back subpanels?
Trying to figure optimal threshold betwen bolt head cap screw and edge of recess for bolt head cap.
Should I add 0.5mm, 0.75mm or 1mm or other.
And also subpanels drill hole diameter for each metric screw.
By default FPE add 0.3mm extra to each.
Fron subpanel is 8 thick and rear subpanel is 4mm thick. So DIN 914 will bulge for 2mm on both sides.
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AMB reference β24 power amplifier .fpd files

Postby amb » October 10th, 2019, 12:49 pm

RainfallSky wrote:Mr Ti, what bolts did you use for front and back subpanels?

For the front subpanel I used #10-32, for the rear, I used #6-32. All are stainless steel socket cap screws.

For some odd reason when I open the FPD files now, all the #6-32 threads show as #6-40. Maybe the newer FPD software made some conversions. Anyone using these files for #6-32 screws should change the type of thread to "(UNC) Unified Coarse".

For your metric bolts, I suggest you get the bolts and make some measurements with a caliper, then determine the sizes of the countersunk portions of the subpanel holes.
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Re: AMB reference β24 power amplifier .fpd files

Postby RainfallSky » October 12th, 2019, 3:20 am

Hmmmm.. measure with a caliper is agood idea.
Thank you.

P.S.:
Got a message from ModuShop that my case is sent.
I still need to plan and order subpanels, one more pair of handles, bottom plate and cap bracket, support L brackets and so on.
Will start build log thread in future but it will be a very slow build.. though I hope to complete this project in 2020.
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Re: AMB reference β24 power amplifier .fpd files

Postby RainfallSky » October 20th, 2019, 1:41 pm

So I got my partly ordered ModuShop case from *.fpd files with correction to metric bolts.
Work looks luxurious..
Some thoughts.
I should have asked to drill mounting holes for handles. Now I need to drill and get rid of burr myself.
Top and bottom steel cover plate is indeed very thin, only 1mm.
Looks and feel very soft..
I am thinking to order 3mm black anodized aluminium bottom cover for testing and maybe top cover too.
Steel cover does not look credible even with various support plates and brackets.
May be 1NPDA04300B case woul be a better candidate from the start.
For now I have no complains of ModuShop case. Very good and pretty. :D

Some photos:
https://imgur.com/qA7Ht4d
https://imgur.com/rjz9jhB
https://imgur.com/iaW42Yq
Last edited by RainfallSky on October 21st, 2019, 12:14 am, edited 1 time in total.
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Re: AMB reference β24 power amplifier .fpd files

Postby amb » October 20th, 2019, 5:40 pm

Very nice!

The steel bottom cover is indeed thin, but the aluminum isn’t better because aluminum is a much softer metal. My reference β24 uses reinforcement bars at the mounting screws to the heatsink brackets, and the transformer mounting plate is attached to the bottom cover with large bolts and nuts at 11 locations, effectively spreading the stress forces. With these measures the steel bottom cover is entirely adequate.
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Re: AMB reference β24 power amplifier .fpd files

Postby RainfallSky » October 21st, 2019, 12:38 am

Yes thin not thick, my bad.. :D

1mm steel plate and 3mm aluminum plate should have be about the same pressure density.
But my case for DAC with about 3mm aluminum bottom plate is very sturdy.
I can't bend it by hand like I can with dissipante steel bottom cover.
And it could be be reinforced too. Plus more dumping and easy to work with.

P.S.: First complains.
Heatsink bracket have about 3mm size mounting holes for top and bottom covers.
They are not taped and even not perfectly round.
Top and bottom steel covers have about 4mm mounting holes.
There is only one kind of screw in the kit that could kind of fit 3mm mounting hole.
Screw of cone shape. And it would be very hard to tighten because bracket is made of steel.
Very weird choice of mounting.
https://imgur.com/ynuRCrZ

There are even more question about mounting ModuShop antivibrations feet's.
Every part of it is illogical..
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Re: AMB reference β24 power amplifier .fpd files

Postby Kabal{MSU} » October 21st, 2019, 7:51 am

RainfallSky wrote:Screw of cone shape.


You mean tapping screws.

RainfallSky wrote:And it would be very hard to tighten because bracket is made of steel.


No, it will not. Just do it once.

P.S. But aluminium top/bottom covers are times better than steel ones. Order it if you can get it shipped cheap.
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Re: AMB reference β24 power amplifier .fpd files

Postby RainfallSky » October 21st, 2019, 3:54 pm

Kabal{MSU} wrote:You mean tapping screws.


I guess so. Now I know naming. Thank you. )

Kabal{MSU} wrote:No, it will not. Just do it once.

P.S. But aluminium top/bottom covers are times better than steel ones. Order it if you can get it shipped cheap.


Hmmmm okey.
Though those tapping screws is still no good for heavy filled bottom.
I tried to search for some dissipante build guides, most lead to DIYAudio forum.
Got some nice ideas from there.
6L6 is a real gem when it comes to build guides.
And yes I plan to switch to aluminum covers.

P.S.: I guess it's time to start my personal build log with a hope to finish Beta24 amp in 2020. I will have a questions in the process from time to time.
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