"reduces voltage fed to transformer"
Oh, I thought the lightbulb(s) should be mounted in series with each rail, between supply and amp
As i understand it, the susy topology needs inverting amps. Which is not the case here.
Susy topology doesn't crosses the feedback loops neither.
As i understand it, the susy topology needs inverting amps. Which is not the case here.
Susy topology doesn't crosses the feedback loops neither.
So I make the input stages of "two" F5 become "one" differential pair stage,
Then, the other side's output will become invert output.
Imho, once you put a diff pair in the circuit, it's a different amp.
The harmonics change.
You can probably see that using a simple sim with no trouble.
_-_-bear
Hi,
Please, I need input on how to choose between these transformers
I will buy two trafos to build seperate monos
I dont know much about R-core trafos, quality etc
SELECTRONIC ::: L'univers électronique :::
230V / 2x 18V 300VA
230V / 2x 18V 500VA
Please, I need input on how to choose between these transformers
I will buy two trafos to build seperate monos
I dont know much about R-core trafos, quality etc
SELECTRONIC ::: L'univers électronique :::
230V / 2x 18V 300VA
230V / 2x 18V 500VA
Ask yourself the following questions:
- what is the maximum current draw possible from each amp, peak?
- at what voltage will the rail run?
- multiply the two numbers.
That is the maximum watts drawn from this amp.
Now, this is roughly identical to "VA".
A 300VA transfomer will deliver maximum 300 watts of power.
BUT, it depends on how it was rated!
There are three rating classes in the USA: CCS, ICAS, and ummm... I forget the proper nomenclature, but "consumer" is close enough.
CCS = "Continuous Commercial Service".
ICAS = "Intermittant Commercial <something> Service" (brain dead today...)
And consumer is less than that.
The rating is based upon % drop under load.
CCS = 10% drop under full load.
So your rails will drop 10% under full load with a CCS rated transformer run at whatever full load for it is. In this case you could draw 300watts from the iron and see a 10% drop.
Greater drop as you go down the chain...
I like to design for better than CCS when feasable.
I think you have to look at the numbers and decide how much Vdrop in the rails you can live with given the likely current draw, and then find out how the manufacturer rates the iron to begin with.
Bottom line, if cost is no object, weight and size not important, larger is better in power iron (with a few less important issues still playing a role), imho.
_-_-bear
- what is the maximum current draw possible from each amp, peak?
- at what voltage will the rail run?
- multiply the two numbers.
That is the maximum watts drawn from this amp.
Now, this is roughly identical to "VA".
A 300VA transfomer will deliver maximum 300 watts of power.
BUT, it depends on how it was rated!
There are three rating classes in the USA: CCS, ICAS, and ummm... I forget the proper nomenclature, but "consumer" is close enough.
CCS = "Continuous Commercial Service".
ICAS = "Intermittant Commercial <something> Service" (brain dead today...)
And consumer is less than that.
The rating is based upon % drop under load.
CCS = 10% drop under full load.
So your rails will drop 10% under full load with a CCS rated transformer run at whatever full load for it is. In this case you could draw 300watts from the iron and see a 10% drop.
Greater drop as you go down the chain...
I like to design for better than CCS when feasable.
I think you have to look at the numbers and decide how much Vdrop in the rails you can live with given the likely current draw, and then find out how the manufacturer rates the iron to begin with.
Bottom line, if cost is no object, weight and size not important, larger is better in power iron (with a few less important issues still playing a role), imho.
_-_-bear
most transformers are rated at a limiting internal temperature that guarantees a reasonably long life into a resistive load. i.e. AC current into a resistor.
We hang a capacitor input filter on our transformers that forces them to run hotter than the manufacturer's rated maximum temperature unless we de-rate using the manufacturer's cap input de-rating factor. This is around 70%.
This means your 300VA transformer cannot deliver more than 210W continuously from a DC supply after the capacitor input filter.
But fortunately transformer feeding ClassAB amplifiers do not run at maximum power all the time. They spend very little time at peak current because the capacitor bank does the job of supplying the peak transients sent to the speaker. The transformer then recharges the capacitor bank. Transformers are also very good at tolerating short term overload. They will even deliver ten times rated current for a very short period, without damage, if you are courageous enough to try it.
You will find that even taking these various measures into account that an 300VA transformer can power ClassAB amplifiers producing a total maximum power from 150W to 300W reasonably well.
We hang a capacitor input filter on our transformers that forces them to run hotter than the manufacturer's rated maximum temperature unless we de-rate using the manufacturer's cap input de-rating factor. This is around 70%.
This means your 300VA transformer cannot deliver more than 210W continuously from a DC supply after the capacitor input filter.
But fortunately transformer feeding ClassAB amplifiers do not run at maximum power all the time. They spend very little time at peak current because the capacitor bank does the job of supplying the peak transients sent to the speaker. The transformer then recharges the capacitor bank. Transformers are also very good at tolerating short term overload. They will even deliver ten times rated current for a very short period, without damage, if you are courageous enough to try it.
You will find that even taking these various measures into account that an 300VA transformer can power ClassAB amplifiers producing a total maximum power from 150W to 300W reasonably well.
Tinitus.
In my opinion the 300 VA trafo is more then enough for a F5 monoblock.
For a stereo F5 class A amp 500 W is perhaps better, but as written here before, one of the most important parts of a amplifier is the powersupply.
Also Amplimo is a very good trafo
and.. dont forget a fuse on the primary side
Last edited by a moderator:
I'm going to give this response in question format, so that everyone who wants to read and think about it can apply the same logic to any amplifier.
What is the VA rating of the transformer?
What is the maximum continuous DC power that the PSU can supply?
Is the amplifier ClassA or ClassAB?
What is the output bias current?
What is the total of all the other front end currents?
What is the supply voltage +V + |-V|?
What is the wattage that the amp draws continuously in quiescent operation?
If the transformer runs @ about half maximum continuous power it usually runs cool enough to not suffer reliability problems.
Is the transformer big enough to not run too hot delivering that power?
If the amp is ClassAB then continue here.
What is the total maximum output power that the ?VA transformer can supply?
What is the total maximum power you expect from you amplifier design?
Is the transformer big enough?
What is the VA rating of the transformer?
What is the maximum continuous DC power that the PSU can supply?
Is the amplifier ClassA or ClassAB?
What is the output bias current?
What is the total of all the other front end currents?
What is the supply voltage +V + |-V|?
What is the wattage that the amp draws continuously in quiescent operation?
If the transformer runs @ about half maximum continuous power it usually runs cool enough to not suffer reliability problems.
Is the transformer big enough to not run too hot delivering that power?
If the amp is ClassAB then continue here.
What is the total maximum output power that the ?VA transformer can supply?
What is the total maximum power you expect from you amplifier design?
Is the transformer big enough?
Thanks, thats all very good and relevant info
I rate double 300Va to be fine with F5
Fore BA-1 and BA-2 I might choose 500Va
As I raised the trafo question, this time, I have to say I was interested in info about the R-core from selectronic
As alternative to toroids, from Amplimo, to have a quality reference
We know now the R-cores in question are made in India
Well, they can do fine things, if they set their mind to it
French people are usually critical enthusiasts, and they use them
Question is still whether quality is consistent, with no humming etc
So far 3 posts about the R-core, two fore and one against, thanks
Another alternative I have yet to try
I might contact AutomaticEurope and ask fore price on custom UI-core, 10A
I rate double 300Va to be fine with F5
Fore BA-1 and BA-2 I might choose 500Va
As I raised the trafo question, this time, I have to say I was interested in info about the R-core from selectronic
As alternative to toroids, from Amplimo, to have a quality reference
We know now the R-cores in question are made in India
Well, they can do fine things, if they set their mind to it
French people are usually critical enthusiasts, and they use them
Question is still whether quality is consistent, with no humming etc
So far 3 posts about the R-core, two fore and one against, thanks
Another alternative I have yet to try
I might contact AutomaticEurope and ask fore price on custom UI-core, 10A
Quality of the Silchar transformers is OK, no different from other R-core manufacture i'm familiar with, Silchar has been producing these transformers for quite some time.
Also neatly packaged in comparison to toroids, possibly convenient for postal ordering, i tend to pick 'm up myself when i go shopping in the Lille area.
R-cores are wound by rotating the bobbins around the wire instead of rotating the wire, plus the bobbins are round and straight, much easier to get tight windings.
Also neatly packaged in comparison to toroids, possibly convenient for postal ordering, i tend to pick 'm up myself when i go shopping in the Lille area.
R-cores are wound by rotating the bobbins around the wire instead of rotating the wire, plus the bobbins are round and straight, much easier to get tight windings.
