@poseidonsvoice
Thank you. The heatsink for each amp is 300mm x 210mm, closer to 5u. I chose that one so as not to have to cheat the transistor leads under the board and still have room for the spring steel clips that mount the power devices to the heatsink. I am going with AMB's bias current recommendation and 26db gain. I'd love lower gain, but don't have the drive to figure out the appropriate capacitor values and what not.
As for sound, here's a run down of my 2 channel for reference. Raspberry Pi streamer - MiniSharc (crossover, EQ) - 2x AMB Gamma 3 DACs (1 for towers, 1 for subs) - amps (a grab bag of AMB B24, Modulus 686, Starkrimson Mono, Starkrimson Ultra) - CBT 24s, and RSS390HF-15 subs. I have a thing for fully differential amps as you may have noticed. I don't do a lot of extended critical listening sessions, as my 2 channel doesn't have a great seating situation in its current location. It's more of a billiard centric setup. With that out of the way, my impressions are below.
The Beta 24 is an excellent amp. The thing that I notice about it in particular is the excellent texture of vocals and instruments, and an overall effortless presentation of music. Imaging is amazing, but that's probably the CBT24s talking. The Beta 24 is a valuable asset in my system. In all other aspects, it hangs with the other amps in my fleet, which is saying a lot.
Thank you. The heatsink for each amp is 300mm x 210mm, closer to 5u. I chose that one so as not to have to cheat the transistor leads under the board and still have room for the spring steel clips that mount the power devices to the heatsink. I am going with AMB's bias current recommendation and 26db gain. I'd love lower gain, but don't have the drive to figure out the appropriate capacitor values and what not.
As for sound, here's a run down of my 2 channel for reference. Raspberry Pi streamer - MiniSharc (crossover, EQ) - 2x AMB Gamma 3 DACs (1 for towers, 1 for subs) - amps (a grab bag of AMB B24, Modulus 686, Starkrimson Mono, Starkrimson Ultra) - CBT 24s, and RSS390HF-15 subs. I have a thing for fully differential amps as you may have noticed. I don't do a lot of extended critical listening sessions, as my 2 channel doesn't have a great seating situation in its current location. It's more of a billiard centric setup. With that out of the way, my impressions are below.
The Beta 24 is an excellent amp. The thing that I notice about it in particular is the excellent texture of vocals and instruments, and an overall effortless presentation of music. Imaging is amazing, but that's probably the CBT24s talking. The Beta 24 is a valuable asset in my system. In all other aspects, it hangs with the other amps in my fleet, which is saying a lot.
Those 2n3055s don’t resemble any of dies in Noopy’s collection here
https://www.richis-lab.de/2N3055.htm
Nick’s transistor
Hey all,
A little while back I completed and shared my build of @LKA's 'H-ENG 60V' amplifier. Well, I enjoyed it so much that naturally I wanted to make his next release which was 'H-ENG 75V'. This time around I went with a 1U case instead of original 1.5U. It was fun to push myself a bit further to make the more powerful amp in a lower-profile chassis, although admittedly I did have a lot more depth to work with this time around. There's a OneDrive link at the bottom with some progress pics - not all glamourous of course.
Progress pics here: https://1drv.ms/f/s!AvzFj8fCrWcFg6I-UtosyARLS0Av_Q
A little while back I completed and shared my build of @LKA's 'H-ENG 60V' amplifier. Well, I enjoyed it so much that naturally I wanted to make his next release which was 'H-ENG 75V'. This time around I went with a 1U case instead of original 1.5U. It was fun to push myself a bit further to make the more powerful amp in a lower-profile chassis, although admittedly I did have a lot more depth to work with this time around. There's a OneDrive link at the bottom with some progress pics - not all glamourous of course.
Progress pics here: https://1drv.ms/f/s!AvzFj8fCrWcFg6I-UtosyARLS0Av_Q
Awesome job. You can use a drill bit of the appropriate diameter to wind the output inductor on. Then take off the drill bit and use a pair of vice grips to hold it tight while you put clear expoxy resin on it. Once it sets you can remove the vice grips and it should be very solid. You can also wind directly over a resistor if it's big enough.
Thanks! Yeah I am still trialing it, but I think it should be OK being Class B and all. The issue I'm having at the moment is that the silpads I got from Jaycar are seemingly not very good at conducting heat so when I push the amp, the case of the outputs gets very hot and is not passing that heat through to the heatsinks.
Not sure what the deal is but I've read that there's a bit of a break in period for these pads. I thought it might be because I'm using nylon screws to hold the transistors down to the L-shaped aluminium bracket and they aren't pulling them down hard enough.
Maybe it's not a good idea to use nylon screws? Won't they stretch and deform slightly with temperature? The pressure on the transistor needs to be consistent otherwise you'll get small pockets under the transistor that aren't in contact with the pads. Thermal paste should improve things.