Hello experts. What is the smallest chassis from the DIY store that is thermally ok for this amp (vanilla build)? It will spend part of its time in a desk setup so size is a concern. Thank you!
4U 300 or 3U 400. Smaller if you want to use a fan.
This really isn’t a desk amp, it burns about 60W of bias current before any losses. I.E., it gets pretty warm…
That said, you still should build it, it’s absolutely amazing.
This really isn’t a desk amp, it burns about 60W of bias current before any losses. I.E., it gets pretty warm…
That said, you still should build it, it’s absolutely amazing.

4U 300 or 3U 400. Smaller if you want to use a fan.
This really isn’t a desk amp
Yeah definitely. It will be on a rack next to the desk but I'd still prefer a smaller footprint.
Is there any difference in the heat dissipation between the Deluxe and Dissipante heatsinks (for the same size chassis)?
Love this build and Super Dumb question to ask. If the toroidal transformer is mounted on the faceplate, what do we do with the hole that mounting screw goes through? Do we normally leave it as it is so it is visible from the front?
A blind hole may be drilled and tapped into the front panel. That is difficult to do.
An easier method is with a mounting bracket:
https://toroid.com/l-bracket/
A diy option is to purchase a Simpson StrongTie A24 bracket or similar from your local home improvement/hardware store and drill mounting holes to suit:
https://www.homedepot.com/p/Simpson...-in-x-2-1-2-in-Galvanized-Angle-A24/100375162
An easier method is with a mounting bracket:
https://toroid.com/l-bracket/
A diy option is to purchase a Simpson StrongTie A24 bracket or similar from your local home improvement/hardware store and drill mounting holes to suit:
https://www.homedepot.com/p/Simpson...-in-x-2-1-2-in-Galvanized-Angle-A24/100375162
A blind hole may be drilled and tapped into the front panel. That is difficult to do.
An easier method is with a mounting bracket:
https://toroid.com/l-bracket/
A diy option is to purchase a Simpson StrongTie A24 bracket or similar from your local home improvement/hardware store and drill mounting holes to suit:
https://www.homedepot.com/p/Simpson...-in-x-2-1-2-in-Galvanized-Angle-A24/100375162
Thank you so much, Ben. Fully understood. I could not find any L mounting bracket for toroidal transformer in my country so might have to go for DIY option from Hardware store.
If you get the silver front panel with the 9 threaded, tapped holes you can mount a riser panel to it, and then the toroidal to that. Many moons ago, a lot of thought went into the design of the baseplate and riser panels so there would always be a dead-horizontally-centered hole for mounting toroidals to the baseplate or the risers. You can also mount risers to the baseplate if you don't want to use the front panel.
The blind LED hole is also tapped, so depending on the size of the transformer you could consider using that (upside down perhaps).
The blind LED hole is also tapped, so depending on the size of the transformer you could consider using that (upside down perhaps).
If you get the silver front panel with the 9 threaded, tapped holes you can mount a riser panel to it, and then the toroidal to that. Many moons ago, a lot of thought went into the design of the baseplate and riser panels so there would always be a dead-horizontally-centered hole for mounting toroidals to the baseplate or the risers. You can also mount risers to the baseplate if you don't want to use the front panel.
View attachment 1037444
The blind LED hole is also tapped, so depending on the size of the transformer you could consider using that (upside down perhaps).
Thank you very much, Jason. Is the riser panel/baseplate strong enough? It looks great and save trouble DIY but i am using 500VA toroidal transformer and they are quite large and heavy.
I put aside this project due to life circumstances and just trying to get into it and start building.
One quick question if I may.. Can this be built with good quality Switch Mode Power Supply instead of toridal transformer with PSU? I have not seen F5 built with SMPS and wondering if it is ok and will not be noticeable downgrade.
Thank you.
One quick question if I may.. Can this be built with good quality Switch Mode Power Supply instead of toridal transformer with PSU? I have not seen F5 built with SMPS and wondering if it is ok and will not be noticeable downgrade.
Thank you.
Thank you so much. Great to hear that it can be done.
My two novice questions if I may..
Q1, Can I use Cosel PBA150F 24v 6.5A SMPS? I have two of them to use for F5 build.
https://en.cosel.co.jp/product/powersupply/PBA/PBA150F/PBA150F-24/
Q2, If I can use Cosel SMPS, do I need Capacitor banks? It looks like it is more problematic to add capacitor banks for SMPS by reading another thread.
My two novice questions if I may..
Q1, Can I use Cosel PBA150F 24v 6.5A SMPS? I have two of them to use for F5 build.
https://en.cosel.co.jp/product/powersupply/PBA/PBA150F/PBA150F-24/
Q2, If I can use Cosel SMPS, do I need Capacitor banks? It looks like it is more problematic to add capacitor banks for SMPS by reading another thread.
Hi @6L6
Sorry to bother you and have I understood correctly that we do not need capacitor banks if we use a pair of SMPS as power supply for F5 but recommend to use DC filter like below one designed by Mark Johnston?
https://diyaudiostore.com/products/smps-dc-filter-p089zb-kit
If so, do we need a pair of this DC filter or one for a pair of SMPS?
Thank you very much...
Sorry to bother you and have I understood correctly that we do not need capacitor banks if we use a pair of SMPS as power supply for F5 but recommend to use DC filter like below one designed by Mark Johnston?
https://diyaudiostore.com/products/smps-dc-filter-p089zb-kit
If so, do we need a pair of this DC filter or one for a pair of SMPS?
Thank you very much...
Hello everyone,
I already asked this on another topic but it was an old topic. So I wanted to guarentee 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. 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.
I already asked this on another topic but it was an old topic. So I wanted to guarentee 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. 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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