Hi @Ben Mah, thanks for the explanation. I can hopefully finish assembling the FE 2022 tomorrow. I will then switch the LEDs in the right channel amp and listen/measure again using the FE 2022 as the preamp.
For the FE 2022 have a 48V SMPS, but with my next digikey order I’ll order higher voltage capacitors.
For the FE 2022 have a 48V SMPS, but with my next digikey order I’ll order higher voltage capacitors.
I've wrapped up the left channel today and it worked🥳 So far it sounds good, the heatsinks do get hot but I can still shortly touch them, also today it's the hottest day in the Bay Area, so I'll test them again in the coming days.
I'll bring them definitely to the Burning Amp 2024 festival, the only thing left is to create a top cover! Thank you very much again @Ben Mah, I've learned a lot and my first impression of the amps is very good!
Here are some pictures:
I'll bring them definitely to the Burning Amp 2024 festival, the only thing left is to create a top cover! Thank you very much again @Ben Mah, I've learned a lot and my first impression of the amps is very good!
Here are some pictures:
A note for other builders: Making the cases from scratch was the most time-consuming part of the project and I am fairly certain it cost me more (including special saw blades and drill bits) than two monoblock cases from Modushop. I got the aluminum from Metal Supermarkets San Jose. The metal was considered off-cuts, as I didn't need large sheets, which resulted in a nice discount. I've ordered the heatsinks from diyaudiostore.com.
Hi @adrianrw ! I was hoping I'd see that you have successfully finished these. Congrats! 👍 Be sure to finish all the testing before you forget - no sense in having those beauties start doing something odd weeks from now.
As for your chassis, I totally agree that it can be very time consuming. I have been slaving away on a BA2018 and so much of it is chassis work!
As for your chassis, I totally agree that it can be very time consuming. I have been slaving away on a BA2018 and so much of it is chassis work!
@Ben Mah, I've been listening to the amps for 1-2h and measured the heatsink temperature with a meat thermometer. The amps do get very hot (in a non-ventilated ca. 30°C room):
- right channel: 70°C at 2.75V over the 1,1Ohm choke
- left channel: 85°C at 3.25V over the 1.3Ohm choke
Lower the current.
Your measured choke resistances may also be suspect. How did you measure them? Most multimeters are not accurate when measuring low resistance values.
I suggest setting the current by assuming the Hammond 193V DCR = 1.0 Ohm, so go for 2.5V drop and see where the temperature ends up at.
Room temperature at 30 degrees C must feel very hot if humidity is high!
Your measured choke resistances may also be suspect. How did you measure them? Most multimeters are not accurate when measuring low resistance values.
I suggest setting the current by assuming the Hammond 193V DCR = 1.0 Ohm, so go for 2.5V drop and see where the temperature ends up at.
Room temperature at 30 degrees C must feel very hot if humidity is high!
I measured with a lower end Fluke multimeter. I turned the amps on again, this times with the windows open and after 15min they are about 60°C right and 65°C left. I will set the choke voltage to 2.5V tomorrow and report on the temperate after 1h of listening to music.
Identical circuit, identical conditions, and two different heat sink temperatures indicate different current and dissipation.
I had measured my Hammond chokes when I first got them and they were 1.0 Ohm.
A fairly accurate way to measure low resistance is the put a higher resistance resistor in series with the low resistance component.. The higher resistance resistor should be able to have its resistance measured accurately. Apply a voltage to the series connected resistor and component, then measure the voltage drop across the resistor and component. The voltage drop across the known resistor can then be used to calculate the current (I = V/R). With the current known, the voltage drop across the component can then be used to calculate its resistance (R = V/I).
If the voltage is fairly low, for instance 5 or 6V, a 200 or 220 Ohm 1/2W resistor would easily work for measuring the resistance of the 193V. Set the meter to mV when measuring the voltage drop across the 193V.
I had measured my Hammond chokes when I first got them and they were 1.0 Ohm.
A fairly accurate way to measure low resistance is the put a higher resistance resistor in series with the low resistance component.. The higher resistance resistor should be able to have its resistance measured accurately. Apply a voltage to the series connected resistor and component, then measure the voltage drop across the resistor and component. The voltage drop across the known resistor can then be used to calculate the current (I = V/R). With the current known, the voltage drop across the component can then be used to calculate its resistance (R = V/I).
If the voltage is fairly low, for instance 5 or 6V, a 200 or 220 Ohm 1/2W resistor would easily work for measuring the resistance of the 193V. Set the meter to mV when measuring the voltage drop across the 193V.
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Hi Ben. Back in 2021 you published this schematic for your V+ power supply. I'll attach it here. Would the snubber values be C5, C6 and R3? And if so, your note mentions "Snubber resistor 29R" which is a different value than what is in the schematic. Which one might it be?
Many thanks!
Attachments
...thinking out loud...I likely should have said the snubber "parts" being C5, C6 and R3, not snubber "values." Saturday night is not the right time for posting! 🍸 Thanks!
Looking at Nelson’s chart I guess it is not🙂 I’ll open the windows and lower the ambient temperature and measure again.
Were you able to keep your hand on it for any length of time? 65 C is most likely to hot to touch.
Perhaps your thermometer is not accurate.
I just put my choke loaded followers back into the system two days ago. The heat sinks are one size larger than yours at 210mm x 300mm x 40mm. Right now I am running the amps at 3.0A. I have 2sk180 instead of THF-51S so it is mounted on an aluminum angle which is mounted directly to the heat sink. The angle dissipates a bit of heat but the heat sink does not get excessively hot.
Measured temperatures using a cooking thermometer:
ambient: 21.5 C
aluminum angle: 53 C
2SK180 case at base next to mounting screw: 83 C
heat sink 49 C
IF you are measuring the heat sink base right next to the THF-51S, perhaps 65 C is acceptable.
What temperature do you measure at the THF-51S case at next to the mounting screw? And the temperature of the fins next to the THF?
How long can you keep your hand on the hottest area of the heat sink fins?
Perhaps your thermometer is not accurate.
I just put my choke loaded followers back into the system two days ago. The heat sinks are one size larger than yours at 210mm x 300mm x 40mm. Right now I am running the amps at 3.0A. I have 2sk180 instead of THF-51S so it is mounted on an aluminum angle which is mounted directly to the heat sink. The angle dissipates a bit of heat but the heat sink does not get excessively hot.
Measured temperatures using a cooking thermometer:
ambient: 21.5 C
aluminum angle: 53 C
2SK180 case at base next to mounting screw: 83 C
heat sink 49 C
IF you are measuring the heat sink base right next to the THF-51S, perhaps 65 C is acceptable.
What temperature do you measure at the THF-51S case at next to the mounting screw? And the temperature of the fins next to the THF?
How long can you keep your hand on the hottest area of the heat sink fins?
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By the way 30 degrees C is quite a hot ambient temperature. Here in Vancouver we have high humidity and if the temperature gets to 30 degrees, it would be very uncomfortable.
I do have amplifiers with varying levels of heat dissipation so I choose my amplifier based on the seasonal temperature. However if the ambient temperature reaches 30 degrees for any great length of time, I would probably get air conditioning. 🙂
I do have amplifiers with varying levels of heat dissipation so I choose my amplifier based on the seasonal temperature. However if the ambient temperature reaches 30 degrees for any great length of time, I would probably get air conditioning. 🙂
It has been the hottest week in the year in the Berkley area this week. We bought an air conditioner in June and we didn’t use it until now, but now we are very happy that we have one. It hopefully soon will cool down so that I can test the amps during the day. I hope it won’t be as hot in Petaluma at the BAF 2024.
Are the amplifier temperatures more reasonable when you cool down your room?
Yesterday when it was hot, could you touch the heat sink fins for any period of time?
What is the temperature of the THF-51S case at its base next to the mounting screw?
Yesterday when it was hot, could you touch the heat sink fins for any period of time?
What is the temperature of the THF-51S case at its base next to the mounting screw?
