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NCC200 V1.4/Cap6 GB

Hi Jurjen,

I am not the organiser of this thread, just a participant in the group buy. I think the person you need to contact is SHOOM (Shaun), but don't worry, - I'm sure he'll see your post on here.

Kind Regards
Roy.
 
Hi Paulski and Jurgen

Nice to have you on board.

Please check your PM box for postage requirements.:cool:
 
Hi All,

I've been looking at the schematic and Les' notes on the schematic where he recommends these 3 capacitors should be Polystyrene.

On the BOM list (thanks to Shaun et al) which I've compiled I see that Shaun has suggested "Silver Mica" and Mark 65 has suggested "Film"

Please excuse my ignorance, but are "Film" caps another name for polystyrene, of would you like me to add the polystyrenes to the list as per Marra's post #122.
Or are there alternative polystyrenes as the ones Marra suggested are rather large and have to be soldered to the underside of the board ?

Thanks for your advice.

Finally, would it be worth setting up a new "build thread" once components are posted out and we start building, where we could post Questions etc. for basic advice, as finding such posts on this current thread is getting increasingly challenging as the thread gets longer and most of the posts are naturally linked to orders.
 
The term film cap is applied to capacitors with a plastic film dielectric, examples being ;-
Polypropylene (PP) film capacitors
Polyester (PET) film capacitors
Polyethylene naphthalate (PEN) film capacitors
Polyphenylene sulfide (PPS) film capacitors
Polytetrafluoroethylene (PTFE) film capacitors
Polystyrene (PS) film capacitors
Polycarbonate (PC) film capacitors
Paper (film) capacitors (MP) and mixed film capacitors

My preference for this position would be Polystyrene.
I haven't tried silver mica in these positions but they do have very good stability, if Shaun has tried them and likes them then they will be good

Alan
 
337alant said:
The term film cap is applied to capacitors with a plastic film dielectric, examples being ;-
Polypropylene (PP) film capacitors
Polyester (PET) film capacitors
Polyethylene naphthalate (PEN) film capacitors
Polyphenylene sulfide (PPS) film capacitors
Polytetrafluoroethylene (PTFE) film capacitors
Polystyrene (PS) film capacitors
Polycarbonate (PC) film capacitors
Paper (film) capacitors (MP) and mixed film capacitors

My preference for this position would be Polystyrene.
I haven't tried silver mica in these positions but they do have very good stability, if Shaun has tried them and likes them then they will be good

Alan
Click to expand...

Thanks Alan, this is really helpful - now I understand the various letters used on the Farnell (and other) websites
I checked the link for Marks suggested "Film caps" and there they were with the suffix "PS" ;) - i.e. polystyrene

Graham
 
grahamdocman said:
Thanks Alan, this is really helpful - now I understand the various letters used on the Farnell (and other) websites
I checked the link for Marks suggested "Film caps" and there they were with the suffix "PS" ;) - i.e. polystyrene

Graham
Click to expand...

I have the silver mica’s in some positions on my new builds so I’m not sure if the made any difference or not as it was an all in one go build. Most of those caps are for HF work so stability may help a little and the mica do that bit pretty well.

Cost wise they are around the same price as styrene or near enough not to matter.

I did try to resist using them right the way through and have styrene on the front end as the mica’s I’ve tried in that spot with other amps sounded a little too etched for my taste.

But that’s one of the really nice parts of DIY.

Choice.:D

Polytetrafluoroethylene (PTFE) film capacitors yaaay but expensive or large or errr both.
 
Hi,

I'm planning to use some spare Aluminium Angle I have in my shed for the heatsink. Its 1 1/4" wide by 3/16" thick. Will this be suitable for the job in hand?

Regards
Roy
 
Meirkat said:
Hi,

I'm planning to use some spare Aluminium Angle I have in my shed for the heatsink. Its 1 1/4" wide by 3/16" thick. Will this be suitable for the job in hand?

Regards
Roy
Click to expand...

Should be OK, as long as decent heat spreading compound is used.

However, I decided to get mine via the GB as they are predrilled with all the holes in the right places for mounting the transistors and predrilled threaded holes in the bases to fix to the case - also remarkable VFM in the GB
 
Meirkat said:
Hi,

I'm planning to use some spare Aluminium Angle I have in my shed for the heatsink. Its 1 1/4" wide by 3/16" thick. Will this be suitable for the job in hand?

Regards
Roy
Click to expand...

Hi Roy

Good question

Ok I’ve called the large U shaped jobbies ‘’heatsinks’’really just out of convenience.

What they really are describes their function more appropriately.

Heat spreaders.

The U shaped spreaders will not be good enough to dissipate all of the heat away from the OP transistors on their own. They rely on good contact with the chassis to dissipate the heat more rapidly so a thin smear of heat sink compound is required between chassis and spreader.

Chassis construction material is going to be just as important to manage the heat dissipated from the OP transistors. I’ve used Aluminium for my builds and yes they do get just warm. I’ve done plenty of reading around the Hacker/NCC builds and paid some attention to faults that have arisen. Quite a few seem to be down to poor heat dissipation due to chassis construction materials.

My take is avoid steel chassis if you can.

For DIY spreaders I’d suggest black anodised Aluminium as a first choice. Most commercial offerings are made this way for good reason.

Take a look at Alan’s superb build for a few hints on good heat management and also my own less well constructed units.

http://www.pinkfishmedia.net/forum/showthread.php?t=160746&highlight=voyager
http://www.pinkfishmedia.net/forum/showthread.php?t=152890&highlight=voyager

People should feel free to make their own choices but for the sake of longevity please make sure those OP transistors are running as cool as possible.

lets keep thing :cool:
 
Hi,
Yes, i understand what your saying regarding the heat spreaders. - What I'm not sure about is if the 1 1/4” Angle Aluminum would be wide enough to mount the outputs on?

This is the enclosure I’ll be using.
Enclosure

And this will be how I’m planning to do the layout.
Layout

So the outputs will be mounted on the Aluminum Angle, and that will be attached to the enclosures heat sinks, all with the appropriate mica insulators and compound.

Will this be sufficient?

Kind regards
Roy.
 
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Your 1 1/4" angle will be fine.I used some similarly sized U section ally when I made my heatsinks and I've had no problems.
As Shaun says just use a reasonable amount of goop and tighten adequately.
Good luck with the build.
 
The effectiveness of the U profile is related to its thickness and effective length + of course the thermal conductivity of the material. 3/16" alu is more than adequate, even 4mm thick is OK.

I have not analysed or calculated the thermal compensation loop in the Naim/NCC circuit, but it may be improved by being in a closed case (like Naim do). However as long as the o/p devices don't get too hot the 0.22R resistors should prevent thermal runaway.

Alu is 3X more conductive than steel. I would avoid steel.

In the end, cooling is all down to surface area exposed to airflow. There is almost no radiated heat when temps are below 80C, so black heatsinks make very little difference. Nearly all the cooling is by convection. Putting huge heatsinks inside a sealed box only aids heatspreading, not overall cooling.

Thermal paste should be applied sparingly. The perfect scenario is just enough to fill any micro-voids between the conducting surfaces. Metal to (mica to) metal contact is better than any thermal paste - the paste is only there to fill the gaps. Use decent paste like Dow Corning 340. The cheap stuff can dry out. Don't be tempted by the amazing figures of stuff like Arctic Silver, it's designed for micros not for power semiconductors.

Happy building chaps.... and by the way.... when will it all be happening?
 
Happy building chaps.... and by the way.... when will it all be happening?


Just waiting for the word from Les that the parts and boards are in hand.

Then we are good to go.
 
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