trafo magnetic shielding?
While on the topic of transformers, does anyone have experience with magnetic shileding of a toroidal xformer?
My concern is building an Aleph Ono clone, and I think it would be prudent to shield the xformer. Can it be as straight-forward as just wrapping a piece of mu metal around the outside edge of the donut? Has anyone had experience doing that?
Thanks!
Ren
While on the topic of transformers, does anyone have experience with magnetic shileding of a toroidal xformer?
My concern is building an Aleph Ono clone, and I think it would be prudent to shield the xformer. Can it be as straight-forward as just wrapping a piece of mu metal around the outside edge of the donut? Has anyone had experience doing that?
Thanks!
Ren
EUVL said:
I was just thinking the same... i mean....using 2 different transformers one for the positive rail and for the negative, in order to reach the power rating of 2KVA.
Well.....i'm only guessing.....wouldn't this solution be better than just one tranformer for each channel?....well....i guess that it might not make this big difference....doens't it?
what do you guys think about this tranformer?
http://www.amplimo.nl/download/1000va.pdf
I don't see any magnetic nor electrostatic shielding...but indeed they cost just 140euro each piece....times two.....it would be 280euro which is half of the estimated 500 for the customized one.
Here sombody told that these tranformers are like plitron.... the price of the standard range is very close, but i don't know about quality thought.......
Does anybody have good hints to share?
Tray to contact http://www.trafox.hr/index.php?option=com_content&task=view&id=25&Itemid=40
or
http://www.transformatori.com/cjeniken.htm
The site is only in croatian, the price for 2kv is 185 Euro.But build quality is very good
or
http://www.transformatori.com/cjeniken.htm
The site is only in croatian, the price for 2kv is 185 Euro.But build quality is very good
Re: trafo magnetic shielding?
Hi Ren,
I did shield my transformers in an ONO. I am now experimenting with my Aleph X.
It works great with my ONO. Check out this thread
Like I mentioned in that thread: it is much easier to shield two small transfomers than one big one. I still did not solve this with my Aleph X. I have a 800 VA transformer, and to prevent the saturation of the Mu-metal, I have to increase the distance between transformer and Mu-metal too much, or use multiple layers. The first solution doesn't fit in the case, the second results into serious heat problems.
Still, the addition of 50Hz ripple is negligable to the 100 hz ripple from the 100 hz still left after the CLCRC, so I won't bother any further on the X until I finished it completely.
Greetings, Harry
Ren said:
My concern is building an Aleph Ono clone, and I think it would be prudent to shield the xformer. Can it be as straight-forward as just wrapping a piece of mu metal around the outside edge of the donut? Has anyone had experience doing that?
Ren
Hi Ren,
I did shield my transformers in an ONO. I am now experimenting with my Aleph X.
It works great with my ONO. Check out this thread
Like I mentioned in that thread: it is much easier to shield two small transfomers than one big one. I still did not solve this with my Aleph X. I have a 800 VA transformer, and to prevent the saturation of the Mu-metal, I have to increase the distance between transformer and Mu-metal too much, or use multiple layers. The first solution doesn't fit in the case, the second results into serious heat problems.
Still, the addition of 50Hz ripple is negligable to the 100 hz ripple from the 100 hz still left after the CLCRC, so I won't bother any further on the X until I finished it completely.Greetings, Harry
i can recommend you toroid`s from : http://www.toroidy.pl/index.php?option=com_content&task=view&id=6&Itemid=13
i know that Peter Daniel using it too....
they are magnetic,electrostatic shielded and totally quiet .
the last price for 2kW toroid -"audio" version was ~ 150Euro (but copper is much more expensive now.... )
i know that Peter Daniel using it too....
they are magnetic,electrostatic shielded and totally quiet .
the last price for 2kW toroid -"audio" version was ~ 150Euro (but copper is much more expensive now....
)
I did a quick check of your power requirements.
If I understand correctly, you want to use 32 FETs per channel, each working at 27V 1.45A (i.e. 40W per FET !!!).
That means you dissipation of the amplifier circuit alone is about 1.2kW (I hope you have big enough heatsinks).
Taking a factor of 2.5 for transformer rating for Class A (I myself use normally a factor of 3 if space allows), then I think you would probably want a transformer of 3kVA at least. Your pulse current into the caps are much higher than the DC current drawn by the amplifier (up to a factor of 10, depending on the size of the caps), so using 2kVA for 1.2kW constant draw is a bit tight, IMHO. The high current and low voltage would mean that the manufacturer would probably have to wind 3 to 4 wires in parallel for each secondary.
What would be the consequences for using only 2kVA for 1.2kW draw ? Probably hum and transformer running very hot.
But there migth be experts around who can give you better professional advices.
Patrick
If I understand correctly, you want to use 32 FETs per channel, each working at 27V 1.45A (i.e. 40W per FET !!!).
That means you dissipation of the amplifier circuit alone is about 1.2kW (I hope you have big enough heatsinks).
Taking a factor of 2.5 for transformer rating for Class A (I myself use normally a factor of 3 if space allows), then I think you would probably want a transformer of 3kVA at least. Your pulse current into the caps are much higher than the DC current drawn by the amplifier (up to a factor of 10, depending on the size of the caps), so using 2kVA for 1.2kW constant draw is a bit tight, IMHO. The high current and low voltage would mean that the manufacturer would probably have to wind 3 to 4 wires in parallel for each secondary.
What would be the consequences for using only 2kVA for 1.2kW draw ? Probably hum and transformer running very hot.
But there migth be experts around who can give you better professional advices.
Patrick
EUVL said:
Very interesting....
i thought that a factor of 2 would have been enough.... 3kVA it's huge!!!
About heat sink i have found so far a 0.1 C/W coefficient and i'm planning....obviosuly...on building monoblocks so i'll split the output mosfet and the power dissipation for each side will be as predicted up to 600-700W.
Therefore my monoblocks will have big sides being a real monster
able to drive anything and with high bias which it takes with it all the adavantages/disadvantages well known of Aleph X high biased.
Assuming you design for 30°C increase in temperature above ambient. For 600W per heatsink, you would need a thermal rating of 0.05 °C/W, which would be something like 80mm fin height, 400mm wide, and 200~250mm length (along the direction of extrusion).
http://www.diyaudio.com/forums/showthread.php?postid=1252700#post1252700
Plus a 3kVA transformer, your housing is going to be hugh !!!
I hope you have big muscles !!!!
Patrick
http://www.diyaudio.com/forums/showthread.php?postid=1252700#post1252700
Plus a 3kVA transformer, your housing is going to be hugh !!!
I hope you have big muscles !!!!
Patrick
ok....here is the datas of the heatsink that i'm going to use :
0.1 C/W for 20cm wide and 30 depth
For each side i'll be using two of them and place on each one 8 mos therefore the temperatur will rise up about 32C, which it is preatty good result.... isn't it?
I still don't know eather the price nor the dimension/weight for this 3KVA tranformer...but i except them to be both high...eheheh!!!
Nevertheless 2 standard 1.5KVAs plitron would cost me about 290euro (the only thing the secondary is above 38V to reduce the current drawing and so the secondary winding thikness )
0.1 C/W for 20cm wide and 30 depth
For each side i'll be using two of them and place on each one 8 mos therefore the temperatur will rise up about 32C, which it is preatty good result.... isn't it?
I still don't know eather the price nor the dimension/weight for this 3KVA tranformer...but i except them to be both high...eheheh!!!
Nevertheless 2 standard 1.5KVAs plitron would cost me about 290euro (the only thing the secondary is above 38V to reduce the current drawing and so the secondary winding thikness )
Stefanoo,
Nor to be a party pooper, but you are really swimming in the deep end. A project like this is not only very expensive, (as you need loads of caps, some abnormally big inductors and some pretty hefty rectifiers for the psu) but also at a difficulty level where I feel you should take a step back and ask yourself:
Am I able to do this with my level of skills and understanding of this?
Do I need all this power ?
Am I able to even run this from my mains outlets in the listening room?
Do I have like 3.000 to 4.000 EUR to spend on this?
Don't get me wrong, I sure am not the one to tell you this can't be done. I believe you have seen that I sure like insanely difficult and big projekts....just make sure you can answer "yes" to the above questions before you proceed.
Magura
Nor to be a party pooper, but you are really swimming in the deep end. A project like this is not only very expensive, (as you need loads of caps, some abnormally big inductors and some pretty hefty rectifiers for the psu) but also at a difficulty level where I feel you should take a step back and ask yourself:
Am I able to do this with my level of skills and understanding of this?
Do I need all this power ?
Am I able to even run this from my mains outlets in the listening room?
Do I have like 3.000 to 4.000 EUR to spend on this?
Don't get me wrong, I sure am not the one to tell you this can't be done. I believe you have seen that I sure like insanely difficult and big projekts....just make sure you can answer "yes" to the above questions before you proceed.
Magura
Hi all the toroidal is key to having a good amplifier.
most toroidal co's make junk.
whats more they have no idea how to build a good transformer.
one point being the use of epoxy coated and vacume impregnated cores.
allong with a lower magnitising current.
i have used a lot of the uk makers most make rubbish.
so i gave up!
i now make my own for my own amplifiers.
i have two ruff and a jovil winders
ps i get board making toroidals
but i get the best
most toroidal co's make junk.
whats more they have no idea how to build a good transformer.
one point being the use of epoxy coated and vacume impregnated cores.
allong with a lower magnitising current.
i have used a lot of the uk makers most make rubbish.
so i gave up!
i now make my own for my own amplifiers.
i have two ruff and a jovil winders
ps i get board making toroidals
but i get the best
Magura said:Stefanoo,
Nor to be a party pooper, but you are really swimming in the deep end. A project like this is not only very expensive, (as you need loads of caps, some abnormally big inductors and some pretty hefty rectifiers for the psu) but also at a difficulty level where I feel you should take a step back and ask yourself:
Am I able to do this with my level of skills and understanding of this?
Do I need all this power ?
Am I able to even run this from my mains outlets in the listening room?
Do I have like 3.000 to 4.000 EUR to spend on this?
Don't get me wrong, I sure am not the one to tell you this can't be done. I believe you have seen that I sure like insanely difficult and big projekts....just make sure you can answer "yes" to the above questions before you proceed.
Magura
Well i don't really see how can i even touch 4000euros to make such a project......
a small calculation......ok?!?! so you will understand the engineering approach that i'm trying to keep on my projects.....
to make one monoblock (i'm talking about decent parts just to evaluate if the project works and sounds the way that i want it to)
1) tranformer ...talking about (accordingly on what it's been said here) between 200euro-300euro
2) capacitors (talking of something like 250.000uf.....yes...250.000uf)
for like... 4 of them ... will be..180-200euro
3) heatsink for such a huge heatsing (one onoblock) we are at about 150-180euro
4) board and resistors and the rest of the part about 50euro ( i ake y own board with the bromograph)
5) cost to select 32 mosfet (150euro) i get like
6) cost of rectifier about 30euro for good ones
7) coils......i don't have clue....i actually not convinced to use a CLC power supply.....i was plannyng on using just a huge amount of capacitors that's all.........
i don't know thought....i think that a 2.2mH toroidal core rated at 25 30 A iron core....wouldn't cost that much...and if it does...i think i can live without this
if at the end of the result you add everything we mentioned above....you'll see that the price doen't go higher than 850-900euro (i over estimated some of the things and even considered the worse price).....and it's still veeeryyy far from the total you were claiming.
Nevertheless i can be wrong with my estimation...i guess i'll let you know when i'lll start buying these parts.
Just keeping in mind this thing:
Before of even starting this DIY mania, i was only interested on reproduction...i was...and still am....a big audiophile....constantly reading audio magazines...going around for audio stores....so i'm "trained" to here the difference between two cables....even the differents of the spikes place under your amplifier...turnable...cd player...or whatever.....or difference of a power cable plugged on the outlet in one direction better than another.....and....!!!
I was used...accustomed at crazyyy prices like 5.000 -10.000 euro for such a insignificant equipment.....that you were fortuned if you would have found inside your favourite amplifier 50.000uf on the filter stage....!
Therefore....i do think that few money will be very worth the efforts to build such a good amplifier.
I hope i was able to explain this concept (unfortunatelly this is not my own language so i can 't really freely express my self in the way that i would really like to...anyways i try all my best!)
Obviously you are ceeeertaaainlllyyy more expert than i'm that is very true.
About the difficolties to make such a beast like run up.....i do agreee with you, very problematic since i would work with high current ...power dissipation...and so on..... i can always step up...plugging at first less mosfet then move up if everything is ok....you know?....that is an approach that i was actually considering.
About power.....i mean....that is a personal choice and i don't think that 100W is that much...it's a good power thought.
I appreciate anyways your interest for my project...what i would have appreciated more....it would have been some usefull upbuilding comment and expecially i don't think that your reply has anything to do with my original thread....but it's ok!!
thank's anyways i just wanted to outline some aspects that's all hop e you won't be bothered from my reply...it is not my intent to offende you.
Ciao.
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