Thank you.
I have this chassis almost ready - but not quite - for the CSK (Sony n- and p-channel VFETs). It is not redy yet, and not tested, but I believe for my Quad electrostatics the big Tokins are better choices. So instead of start from scratch again, this is the reason for the question. Anyway, I can of course start with one mono amplifier. (Post 2362)
I could also use a fan as I guess these rather big heatsinks would help a lot so that the fan does not have to run at full speed.
Regards
I have this chassis almost ready - but not quite - for the CSK (Sony n- and p-channel VFETs). It is not redy yet, and not tested, but I believe for my Quad electrostatics the big Tokins are better choices. So instead of start from scratch again, this is the reason for the question. Anyway, I can of course start with one mono amplifier. (Post 2362)
I could also use a fan as I guess these rather big heatsinks would help a lot so that the fan does not have to run at full speed.
Regards
Attachments
@Ben Mah I'm starting to assemble the parts for the amp. On the power supply there is the Antek AN-5450 toroidal transformer which is probably fine but it has two 50V windings as well as 18V and 12V which would never be used. I assume it would be fine but I was wondering if there was something else you would recommend? Thanks.
Assuming you are building monoblocks, the AN-5450 (500VA) will work fine. The minimum is 400VA. I have Anteks in my monoblocks too, but I went a bit overboard and bought the 600VA versions when I built them as common source BAF2015 50W amps three years ago. Looking back, that definitely was not necessary, but too much is better than not enough.
They also have dual secondaries and low voltage windings. I used the 12V winding for the fan as I have forced air cooling. As for the dual 50V windings, parallel connection of them to a single bridge rectifier is feasible if both windings are exactly the same. If they are not then there will be extra current that flows between the secondaries, which would not be good. The safest way to connect them is to connect each secondary to its own bridge rectifier and then parallel the DC output from both rectifiers.
Having said that, I have the secondaries of my Antek transformers connected in parallel. Phase was observed (Red wires together, Black wires together) and they are only warm after hours of continuous operation. A possible check of the transformer secondaries is to measure the AC voltage of the 50V windings. If they measure exactly the same, then that is a good indication that the windings are identical.
Multiple Winding Transformers
Another
They also have dual secondaries and low voltage windings. I used the 12V winding for the fan as I have forced air cooling. As for the dual 50V windings, parallel connection of them to a single bridge rectifier is feasible if both windings are exactly the same. If they are not then there will be extra current that flows between the secondaries, which would not be good. The safest way to connect them is to connect each secondary to its own bridge rectifier and then parallel the DC output from both rectifiers.
Having said that, I have the secondaries of my Antek transformers connected in parallel. Phase was observed (Red wires together, Black wires together) and they are only warm after hours of continuous operation. A possible check of the transformer secondaries is to measure the AC voltage of the 50V windings. If they measure exactly the same, then that is a good indication that the windings are identical.
Multiple Winding Transformers
Another
As always, thank you for the help. I hadn't thought of/wasn't planning on building the amp as a pair of monoblocks. You can drive both channels with just the one power supply board you designed right? I can see how building it with two separate power supplies (albeit in a single chassis) would make some sense but it also increases the cost by $150 or so. Those 22000uF caps and the choke aren't cheap LOL. I wonder if the sonic improvements are worthwhile? I also didn't look into non-toroidal power transformers since the FirstWatt power supplies are all toroidal.
What would happen if you only used one of the 50V windings and just left the other one unconnected to anything? Bad stuff or no problem? I didn't see anything about that skimming the two links you provided. But using two bridge rectifiers and paralleling the output is a cheap convenient solution.
Hi Paul,
Monoblocks aren't absolutely necessary. And those 80V capacitors aren't cheap.
Not using one 50V winding is a waste of the winding and money.
The PS board can handle the current so using it for both channels is not a problem. You would need a 800VA transformer to supply both channels. The Antek AN-8450 would work.
Each channel dissipates nearly 200W of heat so if you are relying on natural convection cooling, it would be a very big chassis with very large heatsinks on each side. It would be more manageable if forced air cooled, or monoblocks.
High power Class A output costs money!
Monoblocks aren't absolutely necessary. And those 80V capacitors aren't cheap.
Not using one 50V winding is a waste of the winding and money.
The PS board can handle the current so using it for both channels is not a problem. You would need a 800VA transformer to supply both channels. The Antek AN-8450 would work.
Each channel dissipates nearly 200W of heat so if you are relying on natural convection cooling, it would be a very big chassis with very large heatsinks on each side. It would be more manageable if forced air cooled, or monoblocks.
High power Class A output costs money!
With the AN-5450 (500VA) each 50V windings is rated for 5Aac max. Feeding it through a full bridge rectifier will bring the available current to 3Adc so using only 1 winding isn’t safe and will cause your transformer to heat up considerably and cause possible hazards.
Also, using a single 50V winding is equivalent to using a 250VA power transformer...
Also, using a single 50V winding is equivalent to using a 250VA power transformer...
Thanks Ben. I was planning on cannibalizing a Deluxe 5U chassis that currently has an Aleph J in it. But looking at it, that chassis actually is made up of 2 heatsinks on each side so I wonder if I wouldn't actually be getting the benefit of that full heat sink since there can't be much conduction between the two pieces. I wouldn't have thought the 4U heatsink was big enough given how hot it got running the F5 or M2x. I hate background noise when I am listening to music but maybe a fan is the way to go.
Does anybody have a link for larger chassis/heatsinks than the DIYAudioStore.com carries? I spent a little time googling without much luck.
Does anybody have a link for larger chassis/heatsinks than the DIYAudioStore.com carries? I spent a little time googling without much luck.
This might possibly work:
Modushop 5U x 500mm Deep
And right now they have a sale on non-diyAudio chassis.
I use Noctua NF-P12 Redux fans and they are very quiet, and even quieter when run at reduced voltage:
Very Quiet Noctua Fan
There is also the option of reducing the Iq for less dissipation (and lower power output).
Modushop 5U x 500mm Deep
And right now they have a sale on non-diyAudio chassis.
I use Noctua NF-P12 Redux fans and they are very quiet, and even quieter when run at reduced voltage:
Very Quiet Noctua Fan
There is also the option of reducing the Iq for less dissipation (and lower power output).
Last edited:
In my experience you can spend a LOT of time googling and ebaying without much luck. Getting enough size, proper fin alighnment, and the ability to mount directly to the sinks (to avoid multiple thermal junctions) is a tall order. Ben is probably correct in staying with a forced air concept from the get go. Then you can spend brain power on reducing fan noise instead of fighting physics and expense. I've spent time pondering multiple exotic extrusions bolted to a plate, buying old amps (hafler) and pillaging the sinks, Three phase SSR sinks....the price climbs fast and results ???
Ben, I would be interested in a set of Gerbers for my Burning Amp '22 THF-51s if available.
Thanks,
Rog
That Noctua Fan looks nice. Do you strap it onto the outside of the chassis or just leave it sitting near the heat fins?
