Hi
Just ordered F6 pcbs
I have a 2 x 24 500VA toroidal
can the 24 volts be dropped to 18v or am I chasing my tail.
I have done a search on this and there are many different ideas if this can be done or not
I was hoping to use what I have on hand.
THX
Brian
Just ordered F6 pcbs
I have a 2 x 24 500VA toroidal
can the 24 volts be dropped to 18v or am I chasing my tail.
I have done a search on this and there are many different ideas if this can be done or not
I was hoping to use what I have on hand.
THX
Brian
Wind ten turns around the core and measure the voltage that produces. If the center of the core is filled with epoxy, you are pretty much out of luck.
Otherwise you may be able to do a six volt winding you can place in series with the 24 volt winding. Wired one way you will get 30 volts and turning the new winding leads around you will get 18 volts.
Otherwise you may be able to do a six volt winding you can place in series with the 24 volt winding. Wired one way you will get 30 volts and turning the new winding leads around you will get 18 volts.
Unwinding 25% of the turns is probably the simplest (unless there's epoxy, or the secondary is hidden under the primary), but it will become a ~375VA transformer.
If you're adding turns, it makes more sense to me to add turns to the primary, and in the same direction. That will also reduce your output voltage and is a lot less thermally bad than added reversed secondary turns.
If you're adding turns, it makes more sense to me to add turns to the primary, and in the same direction. That will also reduce your output voltage and is a lot less thermally bad than added reversed secondary turns.
It reduces the safety of the insulation to change the primary winding.
if you want to change the primary, a smaller transformer can have its’ secondary placed in opposing series with the larger transformers primary.
Removing windings can work if the coils are not coated with varnish or otherwise bonded. The secondaries are usually wound as the outside windings.
if you want to change the primary, a smaller transformer can have its’ secondary placed in opposing series with the larger transformers primary.
Removing windings can work if the coils are not coated with varnish or otherwise bonded. The secondaries are usually wound as the outside windings.
The 500VA bit complicates it.
Either get the proper transformer or much better use an amp happy with +/-34V rails.
In any case, your desired +/-25V amp will never use 500VA, unless you load each channel with 2 ohm speakers or thereabouts.
What do you intend to feed?
Either get the proper transformer or much better use an amp happy with +/-34V rails.
In any case, your desired +/-25V amp will never use 500VA, unless you load each channel with 2 ohm speakers or thereabouts.
What do you intend to feed?
He's building an F6, aka space heater. He probably wants all of that 500VA 🙂
Brian: if this is approximately your first amp, just buy the correct transformer. While you can modify them safely, Simon is right in that there are risks and you really do need to know what you are doing, and how to test the modified result.
Thanks.
+1 on buying the proper PT (I already suggested that too), doubly so if it´s a Class A power glutton.
ALL kludges are that, kludges, fine (sometimes) for noncritical work.
NOT HERE 😉
+1 on buying the proper PT (I already suggested that too), doubly so if it´s a Class A power glutton.
ALL kludges are that, kludges, fine (sometimes) for noncritical work.
NOT HERE 😉
Im not an expert by any means but have built a few guitar tube amps and a pass ACA
I’ve had this toroidal lying around for years so I might try it out to see if it happens.
Would 2” Mylar tape work to insulate after I get the right voltage.
THX
I’ve had this toroidal lying around for years so I might try it out to see if it happens.
Would 2” Mylar tape work to insulate after I get the right voltage.
THX
300 to 400VA is typical recommendation for F6
So I guess 500VA would be very comfortable overhead
But as mentioned the transformer is suited for 35 volt amplifiers.
Which is very common for simply straight forward 80 to 100 watt Class AB
Not sure if you bought the 60,000u of capacitors yet
Transformer cost is just another thing in the Audio World.
Over time, you'll just have a collection of Transformers
and its better to just forget what you paid for them LOL
So I guess 500VA would be very comfortable overhead
But as mentioned the transformer is suited for 35 volt amplifiers.
Which is very common for simply straight forward 80 to 100 watt Class AB
Not sure if you bought the 60,000u of capacitors yet
Transformer cost is just another thing in the Audio World.
Over time, you'll just have a collection of Transformers
and its better to just forget what you paid for them LOL
Still havent bought some of the parts yet
I have some large power caps on hand but need to look through what I have before I place my final order.
thx again
I have some large power caps on hand but need to look through what I have before I place my final order.
thx again
Recommend getting a pair of 300VA transformers, either 18V or 20V secondaries. Build a dual-mono amplifier.
A dual-mono power supply does two things:
1) Generally increases the total power available to the amplifier
2) Provides excellent stereo separation
The overall effects include improved imaging, can be really holographic with a good amp. Plus greater bass extension and definition. Usually also has reduced power supply noise, as each channel benefits from greater transformer regulation and capacitive filtering. The sonic differences can be quite dramatic.
Best results will be obtained if the preamplifier also has separate power supplies, or at least independent filtration for each channel.
1) Generally increases the total power available to the amplifier
2) Provides excellent stereo separation
The overall effects include improved imaging, can be really holographic with a good amp. Plus greater bass extension and definition. Usually also has reduced power supply noise, as each channel benefits from greater transformer regulation and capacitive filtering. The sonic differences can be quite dramatic.
Best results will be obtained if the preamplifier also has separate power supplies, or at least independent filtration for each channel.
I think (as said above) that a dual-mono supply improves separation of the channels, (but, I have no measurements, just listening to back up that statement.)
Dual 400va transformers into dual power supply boards. F6 amp.
For caps, I know these work well.
https://www.digikey.co.uk/en/products/detail/nichicon/LGY1V123MELA50/2540890
If you think at any point that you may repurpose your filtering / rectification for an amp with higher voltage rails, I'd strongly recommend spending a bit more money and getting 50V caps. Makes the PSU a bit more future proof / flexible. YMMV.