DIY: Pass F5 turbo v2 initiated

[kroyin]

Om is absolutely true, my F5 runs without any, it has gone through 1 Indian summer without dying on me.
This thermostatic thing will be for my Aleph J (to be extended to F5T) which gets considerably more hotter.

Just remember heat is directly proportional to ambient, so a 55c heatsink in winter will mean 70c in summer ....my case is worse ;-) in summers with fan on temp is 50,now at the onset of winter without fan its 58C

To answer Captain's question there are 2 ways an output device like mosfet can fail (this will pass deadly DC to blow up your spks)

--Sudden current surge which mitigated by diodes & thermistors
---Heat which can be mitigated by the thermostatic switch

If you want complete peace then you can have spk protection circuit in between the amps output and the spks input but IMHO its an overkill

& as Om said some amout of thermal protection is also built in to the F5 circuits via the 47.5k NTC thermistors (read the original F5 article it answers a lot of questions) so you may also omit the switch that I suggested

 

[pdhanwada]

Aleph-X 100w Amplifier Construction Notes

THis is good document to go thru which talks about amplifier building to testing. Although this is on aleph series, it can very well be used as guide for F5 building.

THanks
Panud

 

[bijinmb]

I will be using this speaker protection for my Le Monstre build:

Speaker Protection Module

It has built in soft start as well.

 

[Audiodoc]

Speaker protection module kits are available on eBay for $10 which can be easily used for most amplifiers.

 

[anilva]

I was trying to mount the power supply filter boards after soldering the caps and the 0.47 ohms resistors. I mounted them on metal stand-offs to my chassis. As is my normal practice, I checked if any of the PS terminals are showing any sort of short to the chassis. To my surprise both the boards are showing short or very low resistance from the -v, +v and common '0' terminal to the chassis.

I realized that the mount points are not really isolated except for the masking screen. There is a very small isolated island at the centre of every hole, but any standoff will have bigger diameter than that isolated island.

Looks like I have to go and buy insulated standoffs for mounting the PS filter boards.

Usually mount points are kept completely isolated and separate. Probably in the next rev this needs to be corrected.

Cheers.

 

[omishra]

Looks like I have to go and buy insulated standoffs for mounting the PS filter boards.

Usually mount points are kept completely isolated and separate. Probably in the next rev this needs to be corrected.

Sure! At least now standoff and PCB contact needs isolation by mica/nylon washers. If screw heads are wider then also that required from top too.

 

[doors666]

Speaker protection module kits are available on eBay for $10 which can be easily used for most amplifiers.

I believe the current ratings need to be matched with the amp for that, i could be wrong though.

 

[omishra]

I believe the current ratings need to be matched with the amp for that, i could be wrong though.

Current through speakers will be same as any 50W amp. So it should not be a problem.

 

[doors666]

Current through speakers will be same as any 50W amp. So it should not be a problem.

What I meant to say was that the power needs to be matched. A ckt for a 10w amp would probably be different from a 100w one and you cant put a 10w one in a 100w one. I saw some of the ebay ones having current ratings rather than power ratings and hence the comment.

 

[anilva]

Some pictures of my build. Little bit of wiring left. Power supply tested. Shows 35.3 volts DC on both rails on no load condition.

Cheers.

 

[omishra]

Some pictures of my build. Little bit of wiring left. Power supply tested. Shows 35.3 volts DC on both rails on no load condition.

Cheers.

Nice build. So you are flagship bearer for us. Close up please.

You used supplied bridges for rectification. They are for ground isolation between earth and Vgnd. Didn't you use rectifier board with those 16 costly MUR3020? In 6L6 thread of DIYAudio he mentioned that using discrete dual 3020 rectifier with caps made difference in noise floor. Also it wasn't warmer than its ambient.

What I meant to say was that the power needs to be matched. A ckt for a 10w amp would probably be different from a 100w one and you cant put a 10w one in a 100w one. I saw some of the ebay ones having current ratings rather than power ratings and hence the comment.

You are correct! But eBay boards are mostly using 24VDC, 10A load rating relays. So for AC they are okay for many more watts than 100. Can you please point out where did you see speaker protection which is for lesser than 50W? It will help to keep a distance from those products.

Amp may be consuming 100W/ch but those are internal MOSFETs eating up. They are giving out only AC for speaker which will be load current through protection relay. At the max it could be 3-5 A.

 

[grubyhalo]

That's fantastic! Are the the handles fixed to the front panel or screwed down to the heat-sinks?

 

[anilva]

Nice build. So you are flagship bearer for us. Close up please.

You used supplied bridges for rectification. They are for ground isolation between earth and Vgnd. Didn't you use rectifier board with those 16 costly MUR3020? In 6L6 thread of DIYAudio he mentioned that using discrete dual 3020 rectifier with caps made difference in noise floor. Also it wasn't warmer than its ambient.

I am using 50A bridge which I bought separately. The ones I got in the kit will be used for ground isolation. I am not comfortable with MUR rectification. This is do much simpler. Please check what Pass has used in his Turbo build in the picture enclosed in his F5T article. I will ignore so many others who keep giving opinions on basic things and make them look complex.

That's fantastic! Are the the handles fixed to the front panel or screwed down to the heat-sinks?

Handles are connected to the heatsinks.

 

[pdhanwada]

I am using 50A bridge which I bought separately. The ones I got in the kit will be used for ground isolation. I am not comfortable with MUR rectification. This is do much simpler. Please check what Pass has used in his Turbo build in the picture enclosed in his F5T article. I will ignore so many others who keep giving opinions on basic things and make them look complex.

Cheers.

Anilva,

That was quick. Great progress on your side. Can you put down in hand written drawing of how each of the components are connected starting from the transformer to the AMP PCB to out put terminals.

We would need some help on the grouding scheme too.

Thanks
Pandu

 

[anilva]

Anilva,

That was quick. Great progress on your side. Can you put down in hand written drawing of how each of the components are connected starting from the transformer to the AMP PCB to out put terminals.

We would need some help on the grouding scheme too.

It's pretty straight forward. Just keep it simple as it is in the circuit. Ground points are kept to a minimum to avoid loops.

Will try and draw a sketch and circulate.

Update:

Connected everything and tested with light bulb. Every thing OK. Removed the light bulb and powered on. NTC Thermistor burst into pieces due to heavy current (required at the time of charging those massive caps initially). Changed to a heavy duty thermistor and powered on. Everything fine. Biased them nicely for 350mv each. After an hour become hot but not very hot. Must be around 40 degrees.

Had lot of work at home. Disconnected and played through real speakers in the evening. One channel works brilliantly. The other seems to have no gain at all. Need to debug in the night. May be a problem with the jFets.

Will post an update and pictures.

Cheers.

 

[pdhanwada]

Update:

Connected everything and tested with light bulb. Every thing OK. Removed the light bulb and powered on. NTC Thermistor burst into pieces due to heavy current (required at the time of charging those massive caps initially). Changed to a heavy duty thermistor and powered on. Everything fine. Biased them nicely for 350mv each. After an hour become hot but not very hot. Must be around 40 degrees.

Had lot of work at home. Disconnected and played through real speakers in the evening. One channel works brilliantly. The other seems to have no gain at all. Need to debug in the night. May be a problem with the jFets.

Will post an update and pictures.

Cheers.

Wow,

Good work. This looks like a piece of cake for you.

Thanks

 

[anilva]

few more pictures....

 

[sachu888]

Hi Anil,
did you not attach Mosfets to heatsinks?

Regards,
Sachin

 

[anilva]

Hi Anil,
did you not attach Mosfets to heatsinks?

Regards,
Sachin

What you are seeing in the picture are the MUR diodes on individual heatsinks. The MOSFETs are mounted upside down to the main heatsink.

 

[pdhanwada]

sachin/om

Let me know when the GB parts will be shipped.

Thanks