I had my nightmares with buzzy toroids...
I also have a main above 240v.
The cure for me wasn't the big DC trap that is still in use, but buying only fully encapsulated toroids, with both 230 and 245v primaries (Toroidy Supreme for now).
Every other toroid still hums, even with a bucking transformer. I even have a small and cheap r-core that buzzes... not mentioning EI-cores, which are as loud as the music itself.
I also have a main above 240v.
The cure for me wasn't the big DC trap that is still in use, but buying only fully encapsulated toroids, with both 230 and 245v primaries (Toroidy Supreme for now).
Every other toroid still hums, even with a bucking transformer. I even have a small and cheap r-core that buzzes... not mentioning EI-cores, which are as loud as the music itself.
So it was this. It happens with higher outlet V than primary value.
If you have a custom winder closeby or in your state, measure every day your outlet V, for seven days, and draw average value. Then have them wind it on primary accordingly. Trafomatic (amazing quality) here in Serbia does custom toroids, but i expect shipping to be little higher.
Not given the Toroidy transformers. More than 4 times more expensive than a Talema or Block brands. 😈
Well, the voltage has gone to 246V and the transformer is starting to make audible noise again.
I'm going to tinker myself with a step-down device to remove more than ten volts and see what happens.
According to this principle. I already have one built but it's in step-up mode. I had done it for another project.
Stef.
Well, the voltage has gone to 246V and the transformer is starting to make audible noise again.
I'm going to tinker myself with a step-down device to remove more than ten volts and see what happens.
According to this principle. I already have one built but it's in step-up mode. I had done it for another project.
Stef.
Attachments
Stef,
Just so that I am following you. The 'hum' you had mentioned earlier in the thread, was due to your toroid's core saturating due to presence of DC in the mains? I wasn't following (or maybe I am still not following) because I thought the hum was being heard through your speakers.
Best,
Anand.
Just so that I am following you. The 'hum' you had mentioned earlier in the thread, was due to your toroid's core saturating due to presence of DC in the mains? I wasn't following (or maybe I am still not following) because I thought the hum was being heard through your speakers.
Best,
Anand.
Hello,
More tests with a step-down transformer (230v/12v). I also added two 4700uF/10v capacitors to the DC blocker.
243vAC -> 230vAC -> 58vDC (with Saligny PSU)
No more hum and other noise at first sight even with your ear glued to the transformer.
So it comes from two problem, overvoltage and DC but what causes the most noise is the overvoltage of the transformer.
I would have to look if I can't find a 10v transformer somewhere because 58v is too low. Boards need 60v minimum. I also have to increase the consumption of the whole to be sure that it does not come back. There, I only shoot with two resistance of 2K5.
Once I have locked this part, I will reconnect the whole thing to the amp with the two Q17 boards to see what happens to the level of hum and other noise.
Stef.
More tests with a step-down transformer (230v/12v). I also added two 4700uF/10v capacitors to the DC blocker.
243vAC -> 230vAC -> 58vDC (with Saligny PSU)
No more hum and other noise at first sight even with your ear glued to the transformer.
So it comes from two problem, overvoltage and DC but what causes the most noise is the overvoltage of the transformer.
I would have to look if I can't find a 10v transformer somewhere because 58v is too low. Boards need 60v minimum. I also have to increase the consumption of the whole to be sure that it does not come back. There, I only shoot with two resistance of 2K5.
Once I have locked this part, I will reconnect the whole thing to the amp with the two Q17 boards to see what happens to the level of hum and other noise.
Stef.
Attachments
Of course Toroidy Supreme is very expensive, and huge footprint.
I'm sure that other makers may do the same.
But in the end with the many swaps and tricks I did, I have spent much more than the difference...
I'm sure that other makers may do the same.
But in the end with the many swaps and tricks I did, I have spent much more than the difference...
Nice.
What is the PCB size?
I did some tests with my stock of toroid. It's not easy because I have only small toroid of 15VA or 20VA. I would rather need between 20VA and 50VA. The small models collapse and they do not lower the voltage.
This gives inconsistent results.
For 243/245V at the input:
12V 20VA -> 57/58V
9V 15VA -> 58/59V
6V 15VA -> 57V
To have around 60VDC output, it would take an 8V transformer 30-50VA. What I don't have to do the test. 👽
Long live to the SMPS !!!
It's still simpler with the SMPS600RxE. You plug, you select the voltage and it works! 😉
Good evening.
Stef.
What is the PCB size?
I did some tests with my stock of toroid. It's not easy because I have only small toroid of 15VA or 20VA. I would rather need between 20VA and 50VA. The small models collapse and they do not lower the voltage.
This gives inconsistent results.
For 243/245V at the input:
12V 20VA -> 57/58V
9V 15VA -> 58/59V
6V 15VA -> 57V
To have around 60VDC output, it would take an 8V transformer 30-50VA. What I don't have to do the test. 👽
Long live to the SMPS !!!
It's still simpler with the SMPS600RxE. You plug, you select the voltage and it works! 😉
Good evening.
Stef.
Last edited:
Good morning.
I reconnected the 500VA transformer and the Saligny power supply to the amp while flying from the outside. The amplifier is supplied with 59VDC. The system works with the 230V/9V step-down transformer connected before the main transformer. No more 100Hz hum or transformer noise. You have to have your ear glued to the transformer to hear a slight crackling. The boards are with R32=10R and with the GND connected to the earth with a 15R thermistor.
It therefore came well from the overvoltage of the transformer which saturated it.
Another conclusion is that if you want to have the best performance and the lowest noise level, you better be dual powered.
I will be able to put everything back in the box and try to fit the step-down transformer inside the chassis. I will look quietly if I can find a 230V/8V or 240V/9V 20VA/30VA transformer.
At first sight, the sound seems better than with the SMPS power supply (more bass).
Have a good day.
Stef.
I reconnected the 500VA transformer and the Saligny power supply to the amp while flying from the outside. The amplifier is supplied with 59VDC. The system works with the 230V/9V step-down transformer connected before the main transformer. No more 100Hz hum or transformer noise. You have to have your ear glued to the transformer to hear a slight crackling. The boards are with R32=10R and with the GND connected to the earth with a 15R thermistor.
It therefore came well from the overvoltage of the transformer which saturated it.
Another conclusion is that if you want to have the best performance and the lowest noise level, you better be dual powered.
I will be able to put everything back in the box and try to fit the step-down transformer inside the chassis. I will look quietly if I can find a 230V/8V or 240V/9V 20VA/30VA transformer.
At first sight, the sound seems better than with the SMPS power supply (more bass).
Have a good day.
Stef.
Good finding & issue resolved Stef 👍
Is Q17 which version? Is latest Jfet in 2sk170/JFE150 model.
Is Q17 which version? Is latest Jfet in 2sk170/JFE150 model.
Given Stef’s trials and tribulations with DC present in his mains along with higher mains voltages I thought it would be a good exercise to reread Rod Elliot’s treatise on these subjects:
Blocking Mains DC Offset
- a dc stopper circuit is given as an example which is similar to what was presented in post #2007.
Connection of Bucking transformer
- a safe way of lowering your mains voltage (by a small amount).
I’m glad Stef persevered in his goal of finding the cause of all the hum and growl he was hearing with his linear supply. Something all of us can learn from!
Best,
Anand.
Blocking Mains DC Offset
- a dc stopper circuit is given as an example which is similar to what was presented in post #2007.
Connection of Bucking transformer
- a safe way of lowering your mains voltage (by a small amount).
I’m glad Stef persevered in his goal of finding the cause of all the hum and growl he was hearing with his linear supply. Something all of us can learn from!
Best,
Anand.
The size of the pcb is 78*48mm. The figure has a module of two pcb's. Thus, for $ 5 it is possible to order the manufacture of 20 boards. )
You can order manufacture here:
https://www.pcbway.com/project/shareproject/Power_supply_filter.html
If you need gerberes, they are in attachments.
Yes, the last Q17-Turbo 1.2.1 version.
ordered a PCB set of the Q17-Mini 2.0 and the power supply PCB yesterday. 🙂
Stef.
It's a shame. I placed an order yesterday at JLCPCB. Next shot.
Where is the BOM?
Stef.
Stef,
As long as your original order is still in production at JLCPCB, you can add another gerber file for manufacturing. Then pay the additional $ for new pcb's.
Hi Vunce,
They are still in production.
How are you doing ? It asks me to pay the postage in step 2.
Stef.
They are still in production.
How are you doing ? It asks me to pay the postage in step 2.
Stef.
Yes you get the option to add additional pcb boards to the existing order but you need to pay for the additional shipping as they go by the total weight of the package.
I succeeded. You had to click on a button on the far left.
13€ for 2X5 units added to the order.
Thanks for the tips.
Stef.
13€ for 2X5 units added to the order.
Thanks for the tips.
Stef.