DIY :Pass F5 Turbo V2 Joshua & Ali's Documented Build

[jls001]

This thread has an F5 build using two 90 mm 120V AC fans operated at 90V to reduce the speed and noise. We could also look at either silent 230V fans or DC fans. As suggested by a forum member on another thread, one way to reduce the speed of a fan is to wire a resistor of a few Ohms (of appropriate current carrying capacity) in series.

As can be seen on the link given above, the two fans are placed on the back plate, closer to the side-walls cum heat sinks. We can also consider incorporating this in our builds, or think of a variation of this design.

I think the back plate will have enough space, being sparsely populated as it is (just 2 RCA connectors, 4 speaker binding posts and one IEC power inlet and may be a power on/off switch is all there is). 120 mm is 4.72 inch diameter. Two is obviously preferable to make air flow symmetric. The top plate can be milled with lots of holes or slots to allow the hot air to be blown away.

Rohit: thanks for sharing your findings.

Magma: let us know how to hide away the fan

 

[denom]

Fortunately I had opted for the Pass B1 (thanks to the group by). Using that as the pre which seems ideal.

Speakers remaining same - Paradigms 7s. Thinking of downsizing the speakers as well - as our 1 year old toddler needs some playing space. Perhaps some really good bookshelves (exploring some good DIY options)

Hmm, could be a possible blessing in disguise keeping the +ve's in mind
All the best for your new set-up. Be careful with the love affair between the stands & toddler

Sorry Joshua for going OT - will stop with this post
Best wishes for the 'heater' build. Would come in handy for current weather hyeah:

 

[rohitmusic]

There are some liquid cooling options as well like these

I have not tried these so can't comment on their efficiency figures. But they look interesting.

 

[magma]

Joshua

i dont think you should be too concerned if you choose to use 9 inch sinks

I can lay money that your amp will not require forced cooling

heres the cranky monster with 10 inch sinks





its cool for a 5 yr old to touch as reported from the owner
He is was running it full biased in the Delhi ( now Kolkatta ) summer

if he can run this fully biased using the MG75 at 10 inches
You can surely run with the MG98 with 9 inches

 

[sarith]

Looking good!

 

[jetlag]

Ali / Joshua
Great thread. Can't wait for more pics.

Peace
Jetlag

 

[TheCoolestOne]

Ali and Joshua, great thread. The step my step build with pics, pricing and sourcing is a very helpful idea.

Those heatsinks look like monsters indeed.

All the best and looking forward to further posts of the build.

 

[magma]

More Pics







Top plate - 3mm Aluminium
Bottom plate - 6mm Aluminium
Machined and sized right angles etc

Copper Heat spreader
6mm thick
3.5inch by 12 inch - 2nos
total weight 2.6kgs
this automatically adds to my heatsink size and weight
In effect my 7 inch sink goes to 9.5 inches
Plus we get 3 times higher conduction - since copper will conduct 3 times faster from our devices - keeping them as cool as possible


The aluminium chasis wil further add to the dissipation

the other pics are of a custom aluminium extrusion that will be used to build the chasis and mount the sinks and plates
Machined to size and right angled


Price Paid :
Chasis extrusion : rs 1650
Al Top and bottm plates rs 980
Copper heatspreader : rs 1600
Machining costs for spreader and plates : done in house but should cost about rs 240 if done right - the right machine is a moving saw by elumatec
Milling need not be done its too expensive


Where to source :
Your local metal market
I got mine from Gulalwadi - mumbai
The custom extrsuions though were from the Stores


Options :
Instead of an aluminium extrusion
Get a chasis made locally from a metal wroker using a sqaure pipe of Angle
You should save 1600-1800 rs

Top and bottom plates can be sheet metal Steel like the ones used by Bibin
They will cost a fraction of the aluminium ones and also the venting slots can easily be punched out

As for the heatspreader
If you have good sinks with flat surfaces you can mount the devices directly thus removing the spreader itself
In effect again saving close to 2000rs

Another alternative is using an Aluminum heat spreader
This is far more cost effective and should work well too

 

[magma]

Rough frame

it will need to be amended a bit for the fans if we add them

 

[prem]

I am curious. Do the F5 built and sold by Pass Labs have fans in them?

 

[magma]

they dont

and the last guy who built it whome i know of using the same sinks as mine
actaully got confirmation from Pass ( supposedly )
that his wont need them either

 

[jls001]

The two builds are going to have different layouts because the heatsinks are different. Magma will be using flower type heatsink which he already has, and I plan to use the N56 heatsink from Perfect Metals, Bangalore.

Magma's cabinet will be using a frame. Mine is to be decided. I have drafted a rough layout shown in the link below, which is a plan view of the various boards. It is rather a tight fit. Please suggest smarter ideas for the layout. I am giving a link as the picture gets chopped off when embedded due to the large size of the drawing (designed for A1 paper size, to scale).


http://imageshack.com/a/img836/5899/f2tb.png


Overall internal height is planned for 9". The toroidal transformer has 5" height. Is it OK to place some other boards on top of the toroid (with proper support and separation of about 1 inch)? The soft start board and the speaker protection board are about 38 mm (<1.5") at their tallest, and they have a vertical room of 4" to wriggle in. And the rectifier board also can be stacked close to these two boards atop the toroid?

 

[omishra]

The two builds are going to have different layouts because the heatsinks are different. Magma will be using flower type heatsink which he already has, and I plan to use the N56 heatsink from Perfect Metals, Bangalore.

Magma's cabinet will be using a frame. Mine is to be decided. I have drafted a rough layout shown in the link below, which is a plan view of the various boards. It is rather a tight fit. Please suggest smarter ideas for the layout. I am giving a link as the picture gets chopped off when embedded due to the large size of the drawing (designed for A1 paper size, to scale).


http://imageshack.com/a/img836/5899/f2tb.png


Overall internal height is planned for 9". The toroidal transformer has 5" height. Is it OK to place some other boards on top of the toroid (with proper support and separation of about 1 inch)? The soft start board and the speaker protection board are about 38 mm (<1.5") at their tallest, and they have a vertical room of 4" to wriggle in. And the rectifier board also can be stacked close to these two boards atop the toroid?

Joshua, some out of the box thinking -

Can you shift softstart board on back panel from inside covering IEC socket? It matters 4 screws and some spacers around IEC socket to separate softstart from IEC socket.

Also same thing for speaker protection board.

regarding space between amp board and nearest part, remember it has on board diodes which could be mounted vertically to PCB and need 1.5" clearance.

Its okay to place some board over toroidal. We have already done that. You can think of PS boards. Please see it here.

 

[magma]

Heatsinks
machine lapped ( mounting area only )
the rest will be hand buffed before 20 micron anodize





2nd pic
is of a planned layout
GUys please provide inputs advice etc

 

[jls001]

Since magma had already built a frame and wants to use it, it was becoming quite a challenge to squeeze in everything into the the rather tight frame.

Below is what is possible within his frame. Meaning, we don't have enough room:

http://imagizer.imageshack.us/v2/800x600q90/841/cfun.png


So here's the version 2 which has the depth expanded by 60 mm. This one will comfortably accommodate everything:

http://imagizer.imageshack.us/v2/800x600q90/197/67rq.png

With this, I guess we are good to go with cabinet design and general parts layout.

 

[omishra]

Since magma had already built a frame and wants to use it, it was becoming quite a challenge to squeeze in everything into the the rather tight frame.

Below is what is possible within his frame. Meaning, we don't have enough room:

http://imagizer.imageshack.us/v2/800x600q90/841/cfun.png


So here's the version 2 which has the depth expanded by 60 mm. This one will comfortably accommodate everything:

http://imagizer.imageshack.us/v2/800x600q90/197/67rq.png


With this, I guess we are good to go with cabinet design and general parts layout.

Joshua,

I am replying PM from magma. Please contact him. We thought if mono speaker protection could be used. Mount these protection boards just below speaker binding post on the back panel. Use 2 layers of back panel made from 3mm each. Thus you can hide extra screws from backside,

Your frames are 30mm so at back side another layer from inside could create cavity partition of 30mm space. to mount boards. You can use perforated metal/al sheet too, though I prefer same metal everywhere to avoid thermal expansion mismatch.

Also you can stick rectifier board to bottom. All 16 diodes mounted to bottom plate with electrical isolation from plate but thermally coupled. Their legs bet upwards into rectifier board. Wire from bottom up. (Just same way you we mount MOSFETs on heatsink.) You have 6mm base plate use it. you can stack all ps boards.

Regards,

 

[jls001]

@Om: few quick questions:

1) The soft start controls the power on circuitry, so ideally shouldn't affect the audio signal in any way, right?

2) The speaker protection circuitry will come in the signal path. So will it not degrade the sonics? Can we live without it? Or is it too risky?

3) Are the speaker protection circuits available from Hong Kong sellers able to handle both speakers, or we need two of these? (assuming we decide to use it)

Thanks for the suggestion to place the rectifier board on the bottom plate. The bottom plate ought to be sufficient heat sinking for the rectifier diodes.

Also, thanks for suggesting to better utilise the back plate. I will incorporate both suggestions on magma's build. On my build, I am still bent on adding two fans in the back plate :lol: though I know the heatsink I'm planning to use is already huge.

 

[magma]

im thinking of having only 1 fan ( 120mm though )
exhaust from the top plate
mounted on the inside of the top plate

josh
i think personally i will go with the soft start
and give a skip to the speaker protection

btw
if we have to use the speaker protection
Om suggests this

its a high current stereo board
so only 1 board takes both channels

30A Stero Power Amp Amplifier Speaker Protection Board DIY by Yourself | eBay

P>s Josh i dont have the real estate to stick the rectifier board to the bottom do I ?
or can we squeeze it ?

the soft start as i said too
since i have a frame i can use two rear plates and mount it on the inner rear plate
we wont know what possible till we actually populate the cab i think

my copper spreader will arrive from surface grind tomm

get onto the trafo

once that comes we will know how everything fits

 

[magma]

Om what do you suggest
wrt
to
http://imagizer.imageshack.us/v2/800x600q90/197/67rq.pngg

if taking your advice and mounting the rectifier on the base plate

the rectifier board goes between the PSU boards and the trafo
or between the rear plate and the PSU ?

 

[omishra]

Please find my answers inline.

@Om: few quick questions:

1) The soft start controls the power on circuitry, so ideally shouldn't affect the audio signal in any way, right?
[OM]Yes, but that stops mains supply from tripping during cold startup.
2) The speaker protection circuitry will come in the signal path. So will it not degrade the sonics? Can we live without it? Or is it too risky?
[OM]I never used speaker protection as I set proper biasing according to heatsink.
3) Are the speaker protection circuits available from Hong Kong sellers able to handle both speakers, or we need two of these? (assuming we decide to use it)
[OM] They are mono as well as stereo models.
Thanks for the suggestion to place the rectifier board on the bottom plate. The bottom plate ought to be sufficient heat sinking for the rectifier diodes.

Also, thanks for suggesting to better utilise the back plate. I will incorporate both suggestions on magma's build. On my build, I am still bent on adding two fans in the back plate :lol: though I know the heatsink I'm planning to use is already huge.

Also look at this option - cut the rectifier PCB in middle if space problems are more. Please ignore the labels on Paper, they are for different purpose. Only look at mounting methods on plain metal sheet.

Om what do you suggest
wrt
to
http://imagizer.imageshack.us/v2/800x600q90/197/67rq.pngg

if taking your advice and mounting the rectifier on the base plate

the rectifier board goes between the PSU boards and the trafo
or between the rear plate and the PSU ?

Its looks fine but how you will mount that above 5" transformer height.

I can mount below PS Cap bank too.