I want to share my rendition of the 24v Big MoFo. I stil have a few cosmetic decisions to finalize but that has no impact on how good this amplifier sounds
I want to take this opportunity to say thank you to everyone involved with this project! This community is pretty awesome, I never would’ve even attempted any of the projects I’ve completed without DIYaudio.
I also completed an AKSA Lender preamp that works very well with the MoFo.
I want to take this opportunity to say thank you to everyone involved with this project! This community is pretty awesome, I never would’ve even attempted any of the projects I’ve completed without DIYaudio.
I also completed an AKSA Lender preamp that works very well with the MoFo.
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Hello everybody. I thought I would share some of the details of my recent MoFo build with the community. I tried some components different from those in the original bill of material and have really been enjoying the results. As far as physical construction goes, I built mono amps (24V version) much in the style of Bottlehead equipment; a drop-in top plate with the large components on top and circuitry mounted on the bottom side. I utilized the same heatsink that Michael did (Aavid Thermalloy DB120-20). To enhance convective cooling, I mounted the heatsink 3/4 inch off the plate with large diameter aluminum standoffs for added conduction. As shown in the photos, I added a cooling slot pattern under the heatsink to draw air in from the open chassis bottom. High conductance thermal pads (SilPad-600) were used on both sides of the MOSFET package. Here is a summary of the unique parts I used:
1. Choke: Lundahl 2273 Dual Coil Filament Current Choke, wired in parallel. This results in an inductance of about 100 mH, with a measured resistance of 0.8 ohms and a recommended DC current of 3.4 amps. I have used Lundahls in several of my builds and have appreciated the audio and build quality that come with them.
2. Power Supply: Neurochrome SMPS-86, +/-12V switch-mode supply Switch-mode power supply for audio amplifiers.. Available current is 5 amps.
3. Input Capacitor: Jantzen Audio 2.2uF 800V Z-Superior Capacitor. Recommended by an audio friend as a reasonably priced quality capacitor.
4. Misc: Neurochrome THAT Receiver, Mono version THAT Receiver: Differential line receiver / preamp. I used this board to convert a balanced input to single-ended as required by the MoFo. This device is virtually transparent as far as signal quality goes.
Rather than convert the supply to +24V only, and since the THAT receiver requires +/-12V, Tom Christiansen of Neurochrome offered to modify the MoFo circuit to accommodate the 12V bipolar supply. Two cuts and a jumper were required (see modified schematic).
For the case I got to have some fun with my other hobby; wood working. The wood I used was Bubinga, and the finish was 3 coats of General Finishes Arm-R-Seal Oil & Urethane Topcoat. The feet are Herbie's Tenderfeet (soft).
All that's left is the sound and quite frankly, I find it quite amazing for my first endeavor into Class A solid state DIY. Very defined mid bass/bass and non-fatiguing mids and highs. Great soundstage and plenty of power. Glad I built the 24V version. Any comments or questions would be great. This is only my fourth post and I am looking forward to meeting others on the forum.
Steve
1. Choke: Lundahl 2273 Dual Coil Filament Current Choke, wired in parallel. This results in an inductance of about 100 mH, with a measured resistance of 0.8 ohms and a recommended DC current of 3.4 amps. I have used Lundahls in several of my builds and have appreciated the audio and build quality that come with them.
2. Power Supply: Neurochrome SMPS-86, +/-12V switch-mode supply Switch-mode power supply for audio amplifiers.. Available current is 5 amps.
3. Input Capacitor: Jantzen Audio 2.2uF 800V Z-Superior Capacitor. Recommended by an audio friend as a reasonably priced quality capacitor.
4. Misc: Neurochrome THAT Receiver, Mono version THAT Receiver: Differential line receiver / preamp. I used this board to convert a balanced input to single-ended as required by the MoFo. This device is virtually transparent as far as signal quality goes.
Rather than convert the supply to +24V only, and since the THAT receiver requires +/-12V, Tom Christiansen of Neurochrome offered to modify the MoFo circuit to accommodate the 12V bipolar supply. Two cuts and a jumper were required (see modified schematic).
For the case I got to have some fun with my other hobby; wood working. The wood I used was Bubinga, and the finish was 3 coats of General Finishes Arm-R-Seal Oil & Urethane Topcoat. The feet are Herbie's Tenderfeet (soft).
All that's left is the sound and quite frankly, I find it quite amazing for my first endeavor into Class A solid state DIY. Very defined mid bass/bass and non-fatiguing mids and highs. Great soundstage and plenty of power. Glad I built the 24V version. Any comments or questions would be great. This is only my fourth post and I am looking forward to meeting others on the forum.
Steve
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