> 600VA for a 50W amplifier is 12times factor, we would expect it to be cool and quiet with that rating.
I don't use the output power to calculate a transformer.
I use the actual power consumption.
The F5X has 4A bias per channel.
It has +/-16V rails after rectifiers and regulators.
That means 15Vrms, 5.7Arms at the transformer output per rail.
Which in turn means 171W power consumption.
Using that figure x3 will give you 500VA.
But I want to make sure that the core does not get saturated by the pulse current through the rectifiers.
Hence a 600VA core is specified, even though the winding is still 500VA.
It is not too difficult to simulate the peak value of the current pulse once you know the inductance and resistance of the winding.
Patrick
I don't use the output power to calculate a transformer.
I use the actual power consumption.
The F5X has 4A bias per channel.
It has +/-16V rails after rectifiers and regulators.
That means 15Vrms, 5.7Arms at the transformer output per rail.
Which in turn means 171W power consumption.
Using that figure x3 will give you 500VA.
But I want to make sure that the core does not get saturated by the pulse current through the rectifiers.
Hence a 600VA core is specified, even though the winding is still 500VA.
It is not too difficult to simulate the peak value of the current pulse once you know the inductance and resistance of the winding.
Patrick
I use the actual current consumption rather than the 6times to 10times guidance.
4A bias requires a transformer with at least 8Aac secondary winding rating.
8Aac times 2*16Vac results in a 256VA transformer running at 100% of rated capability. It will run hot.
I and others recommend that for cool running the continuous current draw should be around 50% of the winding rating, or a bit less.
That would give a transformer size of around 500VA (well above the 6times guidance).
600VA results in 42.7% of rating instead of 51% for the 500VA.
Our different methods arrive at substantially the same answer.
4A bias requires a transformer with at least 8Aac secondary winding rating.
8Aac times 2*16Vac results in a 256VA transformer running at 100% of rated capability. It will run hot.
I and others recommend that for cool running the continuous current draw should be around 50% of the winding rating, or a bit less.
That would give a transformer size of around 500VA (well above the 6times guidance).
600VA results in 42.7% of rating instead of 51% for the 500VA.
Our different methods arrive at substantially the same answer.
You can simulate one secondary as a 50Hz voltage source with an inductance and a series resistance.
These you either have to measure or ask your Tx supplier.
Then you connect the rest (rectifiers, caps, regulators, load, .....) and can run Spice to check the pulse current through the series R.
The load in a balanced Class A is easiest, as a constant current sink.
That will give you a good idea as to what the peak current of the secondary would look like.
For our purpose, it is accurate enough.
You can pretty much use this also to check your snubbers and whatever else ......
Patrick
These you either have to measure or ask your Tx supplier.
Then you connect the rest (rectifiers, caps, regulators, load, .....) and can run Spice to check the pulse current through the series R.
The load in a balanced Class A is easiest, as a constant current sink.
That will give you a good idea as to what the peak current of the secondary would look like.
For our purpose, it is accurate enough.
You can pretty much use this also to check your snubbers and whatever else ......
Patrick
Yes, I also tried many (Schuro, Tauscher, Multi-PCB, ......) and now I only order from Tomaz of Toroidy.
My Aleph-X 100W has no audible hum unless you open the case and put your ears next to it.
A few things on top :
1) Use a core at least 3x your actual load. The F5X consumes 180W and use 600VA core.
2) Draw a schematics including rectifiers, size of caps, current draw after the caps , and voltage you expect.
3) DON'T use potted ones, even though they look pretty (I leant this from a UK manufacturer for the audio industry).
4) Use one bridge rectifier for each secondary.
If there is still a problem, then you need to clean up the mains.
Maybe a big EI isolation transformer in a separate room ?
Or use a 2000W Ncore with SMPS and a Cordell Func Gen as input to generate a 50Hz low distortion sine wave (as mains).
Patrick
Hi Patrick,
at the moment my Tauscher 800VA are potted, they are a bit small for the given VA rating (150x100).
The amp idles at 235watts
I´m using 4 double schottky diodes per transformer and them a CLC configuration
In front of the whole music system are two big (1200VA) transformers giving 2x115V for balanced AC.(They are in the cellar below)
At the moment there is also a PS Audio Power Plant which at least sees to it that the absolute DC Offset stays around 0V but does not really reduce the hum.
I also tried resistors between the first capacitor bank and the rectifiers and many other things but nothing really worked.
The first pic shows the schotkys, the second the ripple at the first bank and at the second bank (after the L), the third shows the complete power supply with the main board on top.
So if I order in Poland I should go for the non potted Audio version and specify a core for a higher VA rating?
The only problem I´ve got is that the Tauschers are 150mm in diameter and just fit the case, putting in a bigger one would mean a new case.....
William
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Toroidy will be able to build on a different shape core.
Ask for max 150mm diameter and he should select a taller core to give your VA requirement.
Can your case take the bulge where the wires come out?
If so tell Toroidy that, otherwise he may aim for a smaller diameter to make sure the bulge fits to the max radius allowed by the 150mm diam.
Ask for max 150mm diameter and he should select a taller core to give your VA requirement.
Can your case take the bulge where the wires come out?
If so tell Toroidy that, otherwise he may aim for a smaller diameter to make sure the bulge fits to the max radius allowed by the 150mm diam.
l also use these
http://sklep.toroidy.pl/en_US/c/Toroidal-transformers-SUPREME-AUDIO-GRADE-V2/99
and they are simply amazing!
Dead silent in my XA30.5 clone.
http://sklep.toroidy.pl/en_US/c/Toroidal-transformers-SUPREME-AUDIO-GRADE-V2/99
and they are simply amazing!
Dead silent in my XA30.5 clone.
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The Toroidy 800VA without case is dimensioned at 153x65mm. So it should fit.
http://sklep.toroidy.pl/en_US/p/TTSA0800-Transformer-AUDIO-TSA800VA-voltage-to-50V/321
The case with potting will add at least 8~10mm in diameter.
Their potted version 800VA is even 170mm.
http://sklep.toroidy.pl/en_US/p/TTS...rade-transformer-TSAS800VA-voltage-to-50V/418
The unpotted 1000VA is too large for you at 168mm :
http://sklep.toroidy.pl/en_US/p/TTSA1000-Transformer-AUDIO-TSA1000VA-voltage-to-50V/322
But then you already use an isolation transformer and a "large enough" Tauscher.
So maybe the hum (50Hz/100Hz ?) is caused by something else ?
Have you tried replacing the L's by R's ?
Patrick
http://sklep.toroidy.pl/en_US/p/TTSA0800-Transformer-AUDIO-TSA800VA-voltage-to-50V/321
The case with potting will add at least 8~10mm in diameter.
Their potted version 800VA is even 170mm.
http://sklep.toroidy.pl/en_US/p/TTS...rade-transformer-TSAS800VA-voltage-to-50V/418
The unpotted 1000VA is too large for you at 168mm :
http://sklep.toroidy.pl/en_US/p/TTSA1000-Transformer-AUDIO-TSA1000VA-voltage-to-50V/322
But then you already use an isolation transformer and a "large enough" Tauscher.
So maybe the hum (50Hz/100Hz ?) is caused by something else ?
Have you tried replacing the L's by R's ?
Patrick
Hi Patrick,
I´ve got some other transformers from Tauscher for my X-BOSOZ and they also hum (100Hz)
I´ve tried resistors before the diodes, after the diodes but did´t remove the L´s.
What helps is to reduce the load, at 7A bias as they where when driving my Thiels they hummed a lot more than they do now at 4A
There was also a period of time (some months ago) where the humming was almost gone for a few weeks without changing anything......
I also had a look at the Toroidy website, 153mm will not fit as the distance between my heatsinks is 151-152mm.....but the 600VA looks good and maybe can be beefed up a bit as the height is only 58mm (space allows 100).
I´ve sent them an email.
William
I´ve got some other transformers from Tauscher for my X-BOSOZ and they also hum (100Hz)
I´ve tried resistors before the diodes, after the diodes but did´t remove the L´s.
What helps is to reduce the load, at 7A bias as they where when driving my Thiels they hummed a lot more than they do now at 4A
There was also a period of time (some months ago) where the humming was almost gone for a few weeks without changing anything......
I also had a look at the Toroidy website, 153mm will not fit as the distance between my heatsinks is 151-152mm.....but the 600VA looks good and maybe can be beefed up a bit as the height is only 58mm (space allows 100).
I´ve sent them an email.
William
I've had these for some time but never considered them for firstwatt power supplies. The pair on the white board are for all the heaters on the sv572 amp, shown on the breadboard. They are 12v 12a, large current because the regulators for the heaters are very demanding. The one under test is one of a pair 24v 5a for gm70 heaters.
I can't remember where they came from but the ebay example I gave in the earlier post seems to show the same type.
the standard linear power supplies on my firstwatt amps show about 990uv ac on the lines and output and the thd graphs I put up in the F6 thread show some 'features' at 100hz...I will be looking at the ac on the output and rails and also the thd when I've hooked up the F6 to some smps.
The scope shows the 24v5a supply with 1k load to have 4.66mv hash at 694khz. Whether this affects SQ is one of the things to find out. I'm just curious at this stage and I might have to persuade myself to part with £30 to conduct this test(cost of 2 supplies 24v 10a)...
Ed
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These people.....
Toroidal Transformer, Bobbin Wound Components, UL Approved Transformer by SIGA | Siga Transformers
We have been looking around for silent transformers for many years.... tried all the usual suspects... some of them are silent for weeks or months at a time but then go noisy... some you can hear 2m away... then we found the above company...
Have I gone deaf??? I cannot hear my transformer buzzing anymore... No... my hearing is ok... i must have found a manufacturer that knows what he is doing....
these people are very good.... Talk to Alex Diram
Toroidal Transformer, Bobbin Wound Components, UL Approved Transformer by SIGA | Siga Transformers
We have been looking around for silent transformers for many years.... tried all the usual suspects... some of them are silent for weeks or months at a time but then go noisy... some you can hear 2m away... then we found the above company...
Have I gone deaf??? I cannot hear my transformer buzzing anymore... No... my hearing is ok... i must have found a manufacturer that knows what he is doing....
these people are very good.... Talk to Alex Diram
I would have to second Bensen's suggestion for the Selectronic R-Cores. I am using one in my F6 and 2 in my VFET amp (dual mono) and they are the quietest mains transformers that I have ever used. My F6 I took out a 500VA torroid that gave mechanical hum and slotted in the R-Core to the same circuit and silence ensued.
They ship all round Europe and I have never had a problem with them.
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