I've been working on a project on and off for a couple years. A while back I bought a Acurus DIA150 that was known to be broken and the issue undiagnosable. Well I traded some equipment for it and it cost me about 150 bucks so I figured why not.
He had taken it to a shop for repair but they told him, not repairable and then offered to buy it. he said no and just sat on it forever. so I found sabotage and was able to repair it.
well low and behold the amp sucked! overly bloated in the bass region and not an engaging sound at all. It was all in spec and I just didn't like it, so I figured I'd recreate in a fashion which pleased me.
So I began looking for a suitable amp module to put in the amp that looked stable and had a more balanced and engaging sound to it and settled on the JAT501. it was an online developed amp by a youtuber calling himself JohnAudioTech. really great online development of this amp module. lots of input and checking and double checking. well I was sold, love it. at 35-0-35 puts out about 80 watts. well I wanted an active design also, I'm not into passive setups so I hunted for a nice preamp module to match it. well I settled on a LMJ Preamp 9 module, gain 10 and I think the output impedance is 600 ohms. this preamp module has a great reputation for being really analog sounding, but the output impedance a bit too high for me.
so in comes the Kuartlotron buffer. I had built a few of these buffers in stereo boards and saw my opportunity to implement it here. I saw the opportunity to patch the output of the LMJ Preamp 9 through a resistive ladder to about a gain of 3, which is a more appropriate gain for a amp module with a gain of 30db and feed it into the Kuartlotron buffer and then feed the amp.
I can just patch directly into the upper passive preamp section of the original amplifier. I'm also maintaining all the original function of the original amp. so it will have remote volume and input selection even remote on off.
at 4 ohms this amp puts out about 90 watts and at 8 ohms it's 50 watts. I have very efficient speakers and only need about 30 watts to get decent volume. I've made it a remote power supply and decided that i wanted to also add a few voltage rails to the supply that I didn't need for the build but at a future date I will use them to upgrade my dbx 4820 crossover.
so the external rails are
+- 15 volts dc (alpha parallel regulated supply mounted to a larger heatsink then standard and capable of about 3 amps output.
22 volts ac for the LMJ Preamp 9
+- 35 volts dc for the amp modules (it will be a CLC type filter), the primary transformer is 500 va Antek AN52245 toroid.
+- 5 volts dc at 12 amps (that's the prefab aluminum device with T03's on top)
+- 9 volts for the Kuartlotron
He had taken it to a shop for repair but they told him, not repairable and then offered to buy it. he said no and just sat on it forever. so I found sabotage and was able to repair it.
well low and behold the amp sucked! overly bloated in the bass region and not an engaging sound at all. It was all in spec and I just didn't like it, so I figured I'd recreate in a fashion which pleased me.
So I began looking for a suitable amp module to put in the amp that looked stable and had a more balanced and engaging sound to it and settled on the JAT501. it was an online developed amp by a youtuber calling himself JohnAudioTech. really great online development of this amp module. lots of input and checking and double checking. well I was sold, love it. at 35-0-35 puts out about 80 watts. well I wanted an active design also, I'm not into passive setups so I hunted for a nice preamp module to match it. well I settled on a LMJ Preamp 9 module, gain 10 and I think the output impedance is 600 ohms. this preamp module has a great reputation for being really analog sounding, but the output impedance a bit too high for me.
so in comes the Kuartlotron buffer. I had built a few of these buffers in stereo boards and saw my opportunity to implement it here. I saw the opportunity to patch the output of the LMJ Preamp 9 through a resistive ladder to about a gain of 3, which is a more appropriate gain for a amp module with a gain of 30db and feed it into the Kuartlotron buffer and then feed the amp.
I can just patch directly into the upper passive preamp section of the original amplifier. I'm also maintaining all the original function of the original amp. so it will have remote volume and input selection even remote on off.
at 4 ohms this amp puts out about 90 watts and at 8 ohms it's 50 watts. I have very efficient speakers and only need about 30 watts to get decent volume. I've made it a remote power supply and decided that i wanted to also add a few voltage rails to the supply that I didn't need for the build but at a future date I will use them to upgrade my dbx 4820 crossover.
so the external rails are
+- 15 volts dc (alpha parallel regulated supply mounted to a larger heatsink then standard and capable of about 3 amps output.
22 volts ac for the LMJ Preamp 9
+- 35 volts dc for the amp modules (it will be a CLC type filter), the primary transformer is 500 va Antek AN52245 toroid.
+- 5 volts dc at 12 amps (that's the prefab aluminum device with T03's on top)
+- 9 volts for the Kuartlotron
Attachments
Mock UP
I have the heatsinks done, they were a lot of work. and I did the work on the fins and that chunk I took out with a hacksaw. I know eh. I thought about using powertools but I wasn't comfortable. I just really took my time and broke the work up over a week or two. Slow and steady is the way to go on projects like this. it doesn't pay to rush, that's when I make the most mistakes. I'm putting the units fuses onto the side of the 5 volt supply. Each supply is individually fused to if I want to disable a rail because it's not being used. Saves on the power bill.
the output of the +- 35 dc rail is fed into a pair of 3.4mH aircoils and that is fed to the unit. my idea is to then have individual fuses on the main power rails and then it sees the capacitor bank pictured. I thought it would be beneficial to have that after the fuses, some might think that it will overload the fuses on power up going through their charge cycle. but that bank is fed from the inductors so I'm betting the series inductors will limit the power on rush. I guess we will see if I'm right when I power up for the first time 😎
I really like how the amp looks when the heat sinks are integrated into it. Very clean looking, looks really professional and these heat sinks are just so superior to what was there. A full 2.5 pounds heavier and 30% more surface area.
next I'm focusing on the 5 volt, fixing it into the case. you know what's nice about an external powersupply...
SPACE
every time it's about the space and by going external it really opens up a lot of options. I've completed the 501 module with matched inputs bjt's. I haven't powered them up yet but I will soon. I'm very excited to see if this works together.
enjoy the photos
I have the heatsinks done, they were a lot of work. and I did the work on the fins and that chunk I took out with a hacksaw. I know eh. I thought about using powertools but I wasn't comfortable. I just really took my time and broke the work up over a week or two. Slow and steady is the way to go on projects like this. it doesn't pay to rush, that's when I make the most mistakes. I'm putting the units fuses onto the side of the 5 volt supply. Each supply is individually fused to if I want to disable a rail because it's not being used. Saves on the power bill.
the output of the +- 35 dc rail is fed into a pair of 3.4mH aircoils and that is fed to the unit. my idea is to then have individual fuses on the main power rails and then it sees the capacitor bank pictured. I thought it would be beneficial to have that after the fuses, some might think that it will overload the fuses on power up going through their charge cycle. but that bank is fed from the inductors so I'm betting the series inductors will limit the power on rush. I guess we will see if I'm right when I power up for the first time 😎
I really like how the amp looks when the heat sinks are integrated into it. Very clean looking, looks really professional and these heat sinks are just so superior to what was there. A full 2.5 pounds heavier and 30% more surface area.
next I'm focusing on the 5 volt, fixing it into the case. you know what's nice about an external powersupply...
SPACE
every time it's about the space and by going external it really opens up a lot of options. I've completed the 501 module with matched inputs bjt's. I haven't powered them up yet but I will soon. I'm very excited to see if this works together.
enjoy the photos
Attachments
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