Hello everyone,
If anyone reads it and wants to answer my question I would be very happy 🙂 About 2 years ago I built a classic F5v3. For this build I bought the audio grade 18v x 2 / 400va transformer from Toroidy (https://sklep.toroidy.pl/en_US/p/TTSA0400-Transformer-AUDIO-TSA400VA-voltage-to-50V-/318). During the build when I started to bring the voltage at the measurement points to 0.60 for the bias adjustment, the transformer started to shake. It seemed to have difficulty providing the required current. At first I didn't care much about this situation. However, when I turn on the amplifier when the environment is quiet, I can hear the chassis shaking. Therefore, a question mark arose in my mind. The 300va transformer recommended in the build guide. So, should 300va be for each channel or is 300va enough in total? If it is enough, why am I having this problem with a 400va transformer?
I would also like to add that I am using a speaker with a sensitivity of 91db. When no sound source is on, I get a hum sound when I put my ear close to the speaker.
Thank you in advance for your answers.
If anyone reads it and wants to answer my question I would be very happy 🙂 About 2 years ago I built a classic F5v3. For this build I bought the audio grade 18v x 2 / 400va transformer from Toroidy (https://sklep.toroidy.pl/en_US/p/TTSA0400-Transformer-AUDIO-TSA400VA-voltage-to-50V-/318). During the build when I started to bring the voltage at the measurement points to 0.60 for the bias adjustment, the transformer started to shake. It seemed to have difficulty providing the required current. At first I didn't care much about this situation. However, when I turn on the amplifier when the environment is quiet, I can hear the chassis shaking. Therefore, a question mark arose in my mind. The 300va transformer recommended in the build guide. So, should 300va be for each channel or is 300va enough in total? If it is enough, why am I having this problem with a 400va transformer?
I would also like to add that I am using a speaker with a sensitivity of 91db. When no sound source is on, I get a hum sound when I put my ear close to the speaker.
Thank you in advance for your answers.
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Can you post the complete amplifier and power supply schematic that you used?
Is the transformer mounted on the rubber discs?
Post some photos of the mounted transformer.
Is there a shorted turn in the transformer from the mounting arrangement?
Do both ends of the transformer mounting bolt touch the chassis (or are grounded)?
Is the transformer mounted on the rubber discs?
Post some photos of the mounted transformer.
Is there a shorted turn in the transformer from the mounting arrangement?
Do both ends of the transformer mounting bolt touch the chassis (or are grounded)?
But I realized that now, I'm using IRF's instead of FQA's.
And also I'm using this -> https://diyaudiostore.com/products/universal-psu with 50v/10.000uf capacitors.
And also I'm using this -> https://diyaudiostore.com/products/universal-psu with 50v/10.000uf capacitors.
It isn't unknown for multiple builds to have the same error in construction.
We tend to repeat out mistakes. Post some photos.
We tend to repeat out mistakes. Post some photos.
Yes, propably. As you know, it's a bit heavy 🙂 I need to put it out from it's place to take photos.
I'm assuming your F5V3 build uses the schematics on page 2 here: https://www.firstwatt.com/wp-content/uploads/2023/12/art_f5_turbo.pdf
The use of IRF parts wouldn't cause your transformer to shake and 400VA is enough for a stereo build. IIRC, the original production F5 used a 300VA Plitron.
Please post some photos. If you're getting a hum you probably have some wiring that needs tidying up as well.
You might want to continue the discussion here for better exposure: https://www.diyaudio.com/community/threads/an-illustrated-guide-to-building-an-f5.188691/page-118
The use of IRF parts wouldn't cause your transformer to shake and 400VA is enough for a stereo build. IIRC, the original production F5 used a 300VA Plitron.
Please post some photos. If you're getting a hum you probably have some wiring that needs tidying up as well.
You might want to continue the discussion here for better exposure: https://www.diyaudio.com/community/threads/an-illustrated-guide-to-building-an-f5.188691/page-118
My F5 implementation is like this. I probably made a mistake. In general, if I summarize;
I used F5v3 pcb and universal power supply both from diy audio store. Audio Grade 18v X 2/400va transformer from Toroidy and a China origin soft start. On power supply unit, I used MBR20200 schottckys and 4pcs 50v 10.000uf capacitors per rail. Ground line connected to chassis via CL60. When I checked all the wiring, only ground to chassis connection is this.
I see 21.5v dc on each rail in the voltage measurement I made 10 minutes after powering up. Bias is set to 0.55v because vibration increases significantly at 0.60v.
I used F5v3 pcb and universal power supply both from diy audio store. Audio Grade 18v X 2/400va transformer from Toroidy and a China origin soft start. On power supply unit, I used MBR20200 schottckys and 4pcs 50v 10.000uf capacitors per rail. Ground line connected to chassis via CL60. When I checked all the wiring, only ground to chassis connection is this.
I see 21.5v dc on each rail in the voltage measurement I made 10 minutes after powering up. Bias is set to 0.55v because vibration increases significantly at 0.60v.
Attachments
I realized that on https://www.diyaudio.com/community/...cuit-board-v3-illustrated-build-guide.244788/ page, I soldered all the legs of MBR20200ct to the board but on the illustration guide only two legs used. Is this a mistake?