Hi @Ben Mah,
The last couple of weeks were consumed by trying to low-temperature weld my aluminium case which did now work out. So I switched to using screws: my case now looks very similar to yours
Anyway, I thought I would ask before I drill the last couple of holes and get to the wiring and testing part: is the layout below good or should re-orient or re-position some of the components? I think my case is a bit bigger than yours and in opposite orientation.
Note that in the picture the SIT is currently not isolated from the case and the heat sink not attached to the side. I'll use a perforated aluminium top. for cooling. Also, I'll attach the heat sink with a thermal paste and 8 M3 screws.
Thanks, Adrian
The last couple of weeks were consumed by trying to low-temperature weld my aluminium case which did now work out. So I switched to using screws: my case now looks very similar to yours
Anyway, I thought I would ask before I drill the last couple of holes and get to the wiring and testing part: is the layout below good or should re-orient or re-position some of the components? I think my case is a bit bigger than yours and in opposite orientation.
Note that in the picture the SIT is currently not isolated from the case and the heat sink not attached to the side. I'll use a perforated aluminium top. for cooling. Also, I'll attach the heat sink with a thermal paste and 8 M3 screws.
Thanks, Adrian
you'll need some air ........... and then some and then some more
means proper slits in bottom , then same on top cover
and you'll need some heatsinks ........... not just bolted to sides and counting it's heat-wise enough , simply because that thickness is too flimsy to transfer heat - you'll need big holes so output parts is bolted to heatsink directly,
means proper slits in bottom , then same on top cover
and you'll need some heatsinks ........... not just bolted to sides and counting it's heat-wise enough , simply because that thickness is too flimsy to transfer heat - you'll need big holes so output parts is bolted to heatsink directly,
What Zen Mod said.
The inside of the chassis will get hot. Venting of the top only will not be very effective as hot air rises but without openings in the bottom, cooler air will not be able to easily flow into the chassis. Vents in the bottom of the chassis will allow cooler air to enter the chassis and maintain an effective upward air flow. Also key to air flow are feet under the chassis to elevate the chassis to allow air to flow under it to enter the chassis. Tall feet are best.
Also as Zen Mod mentioned, mount the SIT directly on the heat sink for best heat transfer. Cut a hole in the side panel. The hole only needs to be big enough to fit the SIT. Either a circular hole or rectangular hole - whichever is easiest for you to do.
Here are the holes in the bottom of my chassis and the hole in the chassis side wall to allow the 2SK180 and angle mount to be attached directly to the heat sink:
For the component layout, I suggest locating the two bridge rectifiers and capacitor bank this way:
You had previously mentioned the DIY FE 2022. If you plan to mount it in the chassis, be sure that there is enough space between the back panel and the amplifier PCB so that the DIY FE pcb may be mounted between the RCA inputs and the amplifier PCB.
The inside of the chassis will get hot. Venting of the top only will not be very effective as hot air rises but without openings in the bottom, cooler air will not be able to easily flow into the chassis. Vents in the bottom of the chassis will allow cooler air to enter the chassis and maintain an effective upward air flow. Also key to air flow are feet under the chassis to elevate the chassis to allow air to flow under it to enter the chassis. Tall feet are best.
Also as Zen Mod mentioned, mount the SIT directly on the heat sink for best heat transfer. Cut a hole in the side panel. The hole only needs to be big enough to fit the SIT. Either a circular hole or rectangular hole - whichever is easiest for you to do.
Here are the holes in the bottom of my chassis and the hole in the chassis side wall to allow the 2SK180 and angle mount to be attached directly to the heat sink:
For the component layout, I suggest locating the two bridge rectifiers and capacitor bank this way:
You had previously mentioned the DIY FE 2022. If you plan to mount it in the chassis, be sure that there is enough space between the back panel and the amplifier PCB so that the DIY FE pcb may be mounted between the RCA inputs and the amplifier PCB.
@PiAir, maybe something to consider is a DSP crossover and a multichannel DAC to tune in your planned system before start building electronic component based active or passive crossovers. Here are a couple of pointers:
Mitch from Accouratesound has books, videos and also payed service to design the DSP based crossovers.
You'll need an a measurement mic and a multichannel DAC. I have a Beyerdynamic MM1 and a MOTU UltraLite mk5, they work well. This allows you to fine tune cross-over points, slopes, and also correct for time arrival. Also, you can then try multiple amplifier configurations as DSP will adjust for the different gains of the power amps.
Mitch from Accouratesound has books, videos and also payed service to design the DSP based crossovers.
You'll need an a measurement mic and a multichannel DAC. I have a Beyerdynamic MM1 and a MOTU UltraLite mk5, they work well. This allows you to fine tune cross-over points, slopes, and also correct for time arrival. Also, you can then try multiple amplifier configurations as DSP will adjust for the different gains of the power amps.
... after a couple of hours of drawing/drilling. I used 3/8 in ventilation holes. I'm thinking of where to best place the ground connection - possibly in the middle of the red square. For the SIT I cut a hole with 2 x 20mm and 1 x 35mm Forstner bits, I have to do some more cleaning up with a file so that the SIT doesn’t touch the aluminum.
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slightly bigger hole for SIT should be more pleasing to eyes, and also giving better sleep
you can slightly shorten/decrease bottom plate, to have slits on circumference of box bottom
it'll give immensely more air than few tiny holes
never underestimate heat, there is simply no such thing as too big heatsink ....... as soon you hit 50W figure and you're not living in cold cave
you can slightly shorten/decrease bottom plate, to have slits on circumference of box bottom
it'll give immensely more air than few tiny holes
never underestimate heat, there is simply no such thing as too big heatsink ....... as soon you hit 50W figure and you're not living in cold cave
Yep, what Zen Mod said about heat. And it's closer to 100W dissipation, or more, depending on Iq.
I would add more holes in the bottom plate close to and parallel to the heat sink. That is where most of the heat will originate.
I strongly suggest that the power supply filter board be located as shown in the picture that I marked up. Have the DC entry end of the board next to the rectifiers and the DC exit end toward the heat sink. That will keep the unfiltered DC ripple and wires farther away from the audio. The wires will also be shorter.
Here is my chassis bottom, with 7/16" cooling holes and 1 1/4" high feet.
I would add more holes in the bottom plate close to and parallel to the heat sink. That is where most of the heat will originate.
I strongly suggest that the power supply filter board be located as shown in the picture that I marked up. Have the DC entry end of the board next to the rectifiers and the DC exit end toward the heat sink. That will keep the unfiltered DC ripple and wires farther away from the audio. The wires will also be shorter.
Here is my chassis bottom, with 7/16" cooling holes and 1 1/4" high feet.
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Here are a couple more tips:
The amp pcb has some test point (T.P.) locations that may make life easier when testing and measuring. The V- Choke 1 and Choke 2 locations (at the end of the choke wires) are great for measuring Iq. Measure the DC voltage across the two test points and knowing the DC resistance of the choke, the current = V/R (Ohm's Law). There are two Choke 2 SIT S test points on the board. They are identically electrically so use whichever is more convenient to reach.
The single audio PCB can be populated on one side for one channel and populated on the opposite side for the other channel if mirror imaging is desired. The "Left Channel" and "Right Channel" designations on the board are only for identification of the board sides only. The board sides may be used for either channel. The tip here is that if the boards are mounted vertically, it is best to have the board oriented such that the signal input is toward the back of the chassis and the DC voltage input for the SIT bias is toward the front of the chassis.
The amp pcb has some test point (T.P.) locations that may make life easier when testing and measuring. The V- Choke 1 and Choke 2 locations (at the end of the choke wires) are great for measuring Iq. Measure the DC voltage across the two test points and knowing the DC resistance of the choke, the current = V/R (Ohm's Law). There are two Choke 2 SIT S test points on the board. They are identically electrically so use whichever is more convenient to reach.
The single audio PCB can be populated on one side for one channel and populated on the opposite side for the other channel if mirror imaging is desired. The "Left Channel" and "Right Channel" designations on the board are only for identification of the board sides only. The board sides may be used for either channel. The tip here is that if the boards are mounted vertically, it is best to have the board oriented such that the signal input is toward the back of the chassis and the DC voltage input for the SIT bias is toward the front of the chassis.
Also as Zen Mod mentioned, make the hole in the aluminum side panel bigger so there is more clearance for the SIT. You do not want the body of the SIT, which is the drain connection, to short to ground. It will also allow for larger tolerances in locating the SIT and heatsink mounting holes.
@adrianrw, Thanks for your suggestins! I will have a look at it later in the build. For now my speakers and filters are fairly compleet.
The thing that I want to focus first is the hammond 193v choke loaded 2sk180 amp with THF-51S amps and a suitable preamp.
Especially the preamp I am not sure about...
The thing that I want to focus first is the hammond 193v choke loaded 2sk180 amp with THF-51S amps and a suitable preamp.
Especially the preamp I am not sure about...
Right now I am using the DIY FE 2022 as a preamp. It has much lower distortion than the Luminaria, which is resistor loaded, and my resistor loaded 2SK79 preamp.
I have not tried a choke loaded 2SK79 preamp but choke loading should lower the distortion. Choke loading the Luminaria (then it would not be a Luminaria) should also lower the distortion, but I have not tried that either.
diyAudio member pinholer has choke loaded VFETs as preamps and voltage gain stages.
I have not tried a choke loaded 2SK79 preamp but choke loading should lower the distortion. Choke loading the Luminaria (then it would not be a Luminaria) should also lower the distortion, but I have not tried that either.
diyAudio member pinholer has choke loaded VFETs as preamps and voltage gain stages.