I worked on two amplifiers. First one Alpha Nirvana 39 watts classA amp, by Hugh and X. I am very slow at putting things in final case/cage, otherwise it works great from the start. It needs big power supplies and front and back face.
Other amplifier I put together is F5 mutant. I had another project going on with J200/K1529 power mosfets mounted on the heatsink, so I decided to try them with F5 circuit. Offcourse the heatsink is too small to be run without fans. I am using two 12 volt brushless fans at 5 volts, very quiet. This amp sounds amazing on test speakers, I need to finish it and compare it with stock F5 (I have two already).
Other amplifier I put together is F5 mutant. I had another project going on with J200/K1529 power mosfets mounted on the heatsink, so I decided to try them with F5 circuit. Offcourse the heatsink is too small to be run without fans. I am using two 12 volt brushless fans at 5 volts, very quiet. This amp sounds amazing on test speakers, I need to finish it and compare it with stock F5 (I have two already).
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some preliminary measurements
good news: almost flat fr response, almost flat phase (four mid basses must be out of phase), great off axis response
speakers sound pleasant, non-fatiguing, with minor dip at high frequencies, they sound powerful vintage like
they can handle any dynamics, four mid basses is a plus
bad news: there is some cavity resonance ~150Hz, I need to look into how to treat it, may be close the box behind the mid basses
highs are slightly lower, as I did not want to overload tiny dome tweeters, but I am sure they can handle little bigger cap I will be adding later
good news: almost flat fr response, almost flat phase (four mid basses must be out of phase), great off axis response
speakers sound pleasant, non-fatiguing, with minor dip at high frequencies, they sound powerful vintage like
they can handle any dynamics, four mid basses is a plus
bad news: there is some cavity resonance ~150Hz, I need to look into how to treat it, may be close the box behind the mid basses
highs are slightly lower, as I did not want to overload tiny dome tweeters, but I am sure they can handle little bigger cap I will be adding later
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now threse are something special
long time ago I bult transconductance amps based on LM1875, and I like the results
I do have plenty of LM3886, so I decided to try Joe Rasmussen's circuit. It worked with some modifications. Most importantly it sounds way better than applicatiuon note circuit.
Normal circuit is precise, clean, yet sterile and boring.
Transcondectance amp is musical, exciting, juicy and fun. I do equalize fr respose in my listening position, so I know its not due to different fr response as current amps adjust power based on speakers resistance. I do nto know yet what it is, but they sound way better.
I built two pairs of amps, all point to point, all needed indiuvidual DC adjustments. Well worth the effort.
long time ago I bult transconductance amps based on LM1875, and I like the results
I do have plenty of LM3886, so I decided to try Joe Rasmussen's circuit. It worked with some modifications. Most importantly it sounds way better than applicatiuon note circuit.
Normal circuit is precise, clean, yet sterile and boring.
Transcondectance amp is musical, exciting, juicy and fun. I do equalize fr respose in my listening position, so I know its not due to different fr response as current amps adjust power based on speakers resistance. I do nto know yet what it is, but they sound way better.
I built two pairs of amps, all point to point, all needed indiuvidual DC adjustments. Well worth the effort.
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I have been building audio stuff for 30+ years, and if I would place each circuit in perfect purchased box, I would waste 10x more on enclosures than real audio parts.
Plus, I have this experience, which happened many times. I work on project, it's new, modified, tweaked. It woks finally great, but is looks like mess. But it works great. I decide to put it in neat box, and it does not work well. I start tweaking, fixing. Finally, after many repairs it works as prototype was. But it looks like a mess. So what was the gain in putting it in neat box?
WBS, feel free to post pictures, this thread is just for fun while covid is still raging
I build many other amps, and rebuilt some older ones...
here is picture of two 2.1 amps based on LM1875 chips, cheap partsexpress board, with one chip for each channel and bridged out for sub, works fine
I build many other amps, and rebuilt some older ones...
here is picture of two 2.1 amps based on LM1875 chips, cheap partsexpress board, with one chip for each channel and bridged out for sub, works fine
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I was working on germanium based preamps/buffers, when I started working on F1J. I was lucky to obtain two pairs of original SemiSouth and pcb from nice fellows here on diy.
Here are some pictures, first prototype, with leftover heatsinks, that transfer to Dissipante 4U case. I started with linear power supply, previously used for Alpha Nirvana, just rewired for non-symmetrical voltage, but then tested switching power supply. One brick per channel, works great.
Here are some pictures, first prototype, with leftover heatsinks, that transfer to Dissipante 4U case. I started with linear power supply, previously used for Alpha Nirvana, just rewired for non-symmetrical voltage, but then tested switching power supply. One brick per channel, works great.
