I gave up on tapping copper heatsinks. My last attempt resulted in 2 broken bits still stuck in the sink. I had some Dell copper heatsinks (no heat pipe) and they had no aluminum frame. Never again. 
Vunce and I use the exact same angle clamp method with ceramic thermal spacer pads and paste. Works like a champ. Mine is doing 165w easily without complaint.
Vunce and I use the exact same angle clamp method with ceramic thermal spacer pads and paste. Works like a champ. Mine is doing 165w easily without complaint.
Thanks Vunce and X for the information,
No tapping planned for the my copper top piece, only drilling hole for bolt to pass thru. Tapping the aluminum on the cooler. The copper will work the same as the aluminum angle piece you use.
I am going to cut the copper piece in half length wise to reduce risk of shorting transistors and to reduce tapped holes to 2 rather than 4.
This will be a ways in the future, but asking so no suprises later.
MM
No tapping planned for the my copper top piece, only drilling hole for bolt to pass thru. Tapping the aluminum on the cooler. The copper will work the same as the aluminum angle piece you use.
I am going to cut the copper piece in half length wise to reduce risk of shorting transistors and to reduce tapped holes to 2 rather than 4.
This will be a ways in the future, but asking so no suprises later.
MM
Hello!
I finally got to the point where I ordered the PCB's for this (amp boards only since I'm on a budget, and have some stuff lying around).
I have no idea from where they are shipped (India? currency was rupies..), so I don't know how long it will be before they arrive.
I built (and modified) several amps, but the one I keep coming back to is a modified PNP JLH-69 running from some laptop bricks. It has it's limitations, but the sound is so sweet and easy to listen to, I never get tired of listening to that amp. This seems similar in simplistic genius, so I thank AKSA for the design, and hope I will love it as much as the JLH!
Kudos to XRK for the work put in too! I read a lot here on DIYA on the projects you work on, and I can't understand where you get the time and energy to do all of it!? Your practical and theoretical levels seem equally high too! (a lot higher than most of us DIY:ers)
I have read through this tread (and already forgot half of it), and I'm a bit confused by the different iterations and component designations, so I figured I wanted to have a reference schematic for debugging/fault tracing the 8ohm version when I finally get to building it.
I found Minek's sim earlier in the thread, and I modified some values and the component designations to match the 'as built' schematic posted in the first post of the thread. I hope these are the same designations as used on the boards.
It still has the components and associated models Minek put in there, so I guess I will change those later, depending on what I end up using. Maybe I will run some stability sim too etc.
For now I have only had a look at some currents vs frequency, and I did a basic plot of the output impedance by feeding 1Vac via a 1ohm resistance to the output, and plotting the Vout (as seen in the sim). Basically the Vout should then correspond to output impedance mV=mOhm.
It seems nice and low in the bass, and climbs a bit with frequency. Not sure what impact the phase of the output impedance could have on sound, but I don't think it's anything to worry about.
I saw general comments about output impedance (damping), but don't remember seeing a plot in the thread, so here it is.
I have a preliminary plan to use a case and PSU from another project that I hope will be able to take the heat, but that will come later.
Do you see some issues with the sim/schematic, or comments in general?
I finally got to the point where I ordered the PCB's for this (amp boards only since I'm on a budget, and have some stuff lying around).
I have no idea from where they are shipped (India? currency was rupies..), so I don't know how long it will be before they arrive.
I built (and modified) several amps, but the one I keep coming back to is a modified PNP JLH-69 running from some laptop bricks. It has it's limitations, but the sound is so sweet and easy to listen to, I never get tired of listening to that amp. This seems similar in simplistic genius, so I thank AKSA for the design, and hope I will love it as much as the JLH!
Kudos to XRK for the work put in too! I read a lot here on DIYA on the projects you work on, and I can't understand where you get the time and energy to do all of it!? Your practical and theoretical levels seem equally high too! (a lot higher than most of us DIY:ers)
I have read through this tread (and already forgot half of it), and I'm a bit confused by the different iterations and component designations, so I figured I wanted to have a reference schematic for debugging/fault tracing the 8ohm version when I finally get to building it.
I found Minek's sim earlier in the thread, and I modified some values and the component designations to match the 'as built' schematic posted in the first post of the thread. I hope these are the same designations as used on the boards.
It still has the components and associated models Minek put in there, so I guess I will change those later, depending on what I end up using. Maybe I will run some stability sim too etc.
For now I have only had a look at some currents vs frequency, and I did a basic plot of the output impedance by feeding 1Vac via a 1ohm resistance to the output, and plotting the Vout (as seen in the sim). Basically the Vout should then correspond to output impedance mV=mOhm.
It seems nice and low in the bass, and climbs a bit with frequency. Not sure what impact the phase of the output impedance could have on sound, but I don't think it's anything to worry about.
I saw general comments about output impedance (damping), but don't remember seeing a plot in the thread, so here it is.
I have a preliminary plan to use a case and PSU from another project that I hope will be able to take the heat, but that will come later.
Do you see some issues with the sim/schematic, or comments in general?
Attachments
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Hi Rallyfinnen,
Thanks for taking an interest in this amp. If you bought the boards from my shop, they ship from the USA. (I see your order now, they will ship out today). I’ll let Aksa answer your question on output impedance. I think the way to test it is to monitor the voltage drop at the output load. You don’t want to stick a 1ohm series resistor between the amp and the load because that’s like making the amp have at best, a 1ohm output impedance. It’s a much lower value.
Good luck on your build!
Thanks for taking an interest in this amp. If you bought the boards from my shop, they ship from the USA. (I see your order now, they will ship out today). I’ll let Aksa answer your question on output impedance. I think the way to test it is to monitor the voltage drop at the output load. You don’t want to stick a 1ohm series resistor between the amp and the load because that’s like making the amp have at best, a 1ohm output impedance. It’s a much lower value.
Good luck on your build!
@marconi118:
Sorry, don't have it at the moment, but I posted most of it in the JLH thread a while back, Here are some examples:
https://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-588.html#post6081070
https://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-595.html#post6090279
https://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-730.html#post6383498
However, I never saw stability problems, so the compensation in the last link is just an idea.
I do believe in big caps in the JLH based on simulation and listening tests (in every position basically), and the floating ground (again with a lot of capacitance, since it was already available on the zerozone PCB) did some stuff to the subjective sound too. Read sublimed JLH1969
Tweaking the 'resistor divider' for the bootstrapped output transistor gave considerable reduction in distortion. I think that tweaking will be individual to the output transistors used, to optimize the current sharing between the transistors (a matter of taste too, since even harmonics decrease with better current sharing). Optimal Iq for minimum distortion also varies with different transistors, depending on where they are most linear. I have just over 1A Iq since that was the best region for the transistors I have (tweaked while looking at FFT).
It is still lacking a little bit in bass control, but it's a lot better than in the beginning, and compared to any standard JLH. Sounds pretty good on metal and other 'complicated music' too, but absolutely shines on any acoustic music, male voices etc. Electric guitar (distorted) on some recordings is really harsh on my ears with most amps, but not so with the JLH.
I built several JLH's, and the modified PNP Zero zone has measured and sounded best.
Dual mono with HP laptop bricks at only 19V, but the power is ok since I don't usially listen loud.
If I remember correctly, I have also decreased gain a little bit (again more feedback, lower distortion), since I have good voltage swing from the DAC. Carbon resistors in the feedback. From memory I measured distortion at abt -90dB @ 1W with H2 and H3 at abt the same level, and the rest not visible. I think I posted some measurements in the JLH tread too.
Very clean FFT with the bricks, no hum, only a very small 'leak' of 66kHz on the output of the amp, but it does not seem to cause IMD, and I definitely can't hear it. Running it with DIY speakers inspired by Troels PMS, maybe around 88dB sensitivity, but a lot of care was taken to make them an easy load.
Sorry about the offtopic...
XRK: Ok! Could still take a long time before they arrive, It's a mess with the customs here in Sweden nowadays, every little package from outside EU is being checked and they charge handling costs and taxes on everything On top of that, handling can take quite some time, especially now with x-mas approaching. I'm not sure I will have them for x-mas, but it would make a nice project for the holidays if I do. Just need to get the components too..
BTW, do you have any indication on how many of these have been built? I guess PCB-sales should give an indication even if some made their own PCB's?
Sorry, don't have it at the moment, but I posted most of it in the JLH thread a while back, Here are some examples:
https://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-588.html#post6081070
https://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-595.html#post6090279
https://www.diyaudio.com/forums/solid-state/3075-jlh-10-watt-class-amplifier-730.html#post6383498
However, I never saw stability problems, so the compensation in the last link is just an idea.
I do believe in big caps in the JLH based on simulation and listening tests (in every position basically), and the floating ground (again with a lot of capacitance, since it was already available on the zerozone PCB) did some stuff to the subjective sound too. Read sublimed JLH1969
Tweaking the 'resistor divider' for the bootstrapped output transistor gave considerable reduction in distortion. I think that tweaking will be individual to the output transistors used, to optimize the current sharing between the transistors (a matter of taste too, since even harmonics decrease with better current sharing). Optimal Iq for minimum distortion also varies with different transistors, depending on where they are most linear. I have just over 1A Iq since that was the best region for the transistors I have (tweaked while looking at FFT).
It is still lacking a little bit in bass control, but it's a lot better than in the beginning, and compared to any standard JLH. Sounds pretty good on metal and other 'complicated music' too, but absolutely shines on any acoustic music, male voices etc. Electric guitar (distorted) on some recordings is really harsh on my ears with most amps, but not so with the JLH.
I built several JLH's, and the modified PNP Zero zone has measured and sounded best.
Dual mono with HP laptop bricks at only 19V, but the power is ok since I don't usially listen loud.
If I remember correctly, I have also decreased gain a little bit (again more feedback, lower distortion), since I have good voltage swing from the DAC. Carbon resistors in the feedback. From memory I measured distortion at abt -90dB @ 1W with H2 and H3 at abt the same level, and the rest not visible. I think I posted some measurements in the JLH tread too.
Very clean FFT with the bricks, no hum, only a very small 'leak' of 66kHz on the output of the amp, but it does not seem to cause IMD, and I definitely can't hear it. Running it with DIY speakers inspired by Troels PMS, maybe around 88dB sensitivity, but a lot of care was taken to make them an easy load.
Sorry about the offtopic...
XRK: Ok! Could still take a long time before they arrive, It's a mess with the customs here in Sweden nowadays, every little package from outside EU is being checked and they charge handling costs and taxes on everything
On top of that, handling can take quite some time, especially now with x-mas approaching. I'm not sure I will have them for x-mas, but it would make a nice project for the holidays if I do. Just need to get the components too..BTW, do you have any indication on how many of these have been built? I guess PCB-sales should give an indication even if some made their own PCB's?
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Still a happy listener too I hope?
I have found that the latest build is always the greatest at first, but then some of the flaws start to shine through, and I go back to the JLH.
Before I had the JLH I would go in search for another build. Now I'm 'just' in search of something as good sounding as the JLH, but a (little) bit more powerful and with better grip of the bass. I even think I could live with the power I get from 19V single rail (9,5V dual floating) 99% of the time. I think it's mainly when friends come to listen and want to 'crank it up' when it falls flat, since most of my friends are not interested in HiFi, they care more about sound pressure than sound quality if I put it like that
I have found that the latest build is always the greatest at first, but then some of the flaws start to shine through, and I go back to the JLH.
Before I had the JLH I would go in search for another build. Now I'm 'just' in search of something as good sounding as the JLH, but a (little) bit more powerful and with better grip of the bass. I even think I could live with the power I get from 19V single rail (9,5V dual floating) 99% of the time. I think it's mainly when friends come to listen and want to 'crank it up' when it falls flat, since most of my friends are not interested in HiFi, they care more about sound pressure than sound quality if I put it like that
Hi X,
You did not miss it !
Alpha Nirvana 39w 8ohm Class A Amp
You helped me set up the AN using modified SMPS with silent Noctua fans.
It's my favorite winter amp!
Cheers,
Jacques
You did not miss it !
Alpha Nirvana 39w 8ohm Class A Amp
You helped me set up the AN using modified SMPS with silent Noctua fans.
It's my favorite winter amp!
Cheers,
Jacques
Congratulations, Jacques!!
Beautiful work, and I'm so pleased you love the sound!!
Rallyfinnen,
The basis of the AN was the original Alpha, which was heavily influenced by the Aleph J from Nelson Pass. I first listened to the JLH 10W in 1969 and was, like you, entranced. I never forget that experience, and wanted to do something which ranked with the JLH.
Unless you have an AB comparison between the AN and the JLH you will never know. BUT, the AN is far more powerful, and much more efficient (43% at full power compared with the 22% JLH) and its levels of distortion (or harmonics, if you prefer) are quite similar although the H3 harmonic starts to predominate on the JLH at the higher outputs. The AN maintains a consistent harmonic profile almost to clip, and this improves the clarity at high outputs.
I think it's reasonable to assume that everyone who has built the AN has not been disappointed, and some thinks it's the best amp they have. It's all relative, and significantly no one has compared it to the JLH, but I would think it would rank, perhaps as good, and definitely much more powerful.
There is a lot of information on the thread, please read through it before you start, and if you have unanswered questions, ask me or X.
Enjoy the build - it's a nice pcb!
Cheers,
Hugh
Beautiful work, and I'm so pleased you love the sound!!
Rallyfinnen,
The basis of the AN was the original Alpha, which was heavily influenced by the Aleph J from Nelson Pass. I first listened to the JLH 10W in 1969 and was, like you, entranced. I never forget that experience, and wanted to do something which ranked with the JLH.
Unless you have an AB comparison between the AN and the JLH you will never know. BUT, the AN is far more powerful, and much more efficient (43% at full power compared with the 22% JLH) and its levels of distortion (or harmonics, if you prefer) are quite similar although the H3 harmonic starts to predominate on the JLH at the higher outputs. The AN maintains a consistent harmonic profile almost to clip, and this improves the clarity at high outputs.
I think it's reasonable to assume that everyone who has built the AN has not been disappointed, and some thinks it's the best amp they have. It's all relative, and significantly no one has compared it to the JLH, but I would think it would rank, perhaps as good, and definitely much more powerful.
There is a lot of information on the thread, please read through it before you start, and if you have unanswered questions, ask me or X.
Enjoy the build - it's a nice pcb!
Cheers,
Hugh
Hi X,
You did not miss it !
Alpha Nirvana 39w 8ohm Class A Amp
You helped me set up the AN using modified SMPS with silent Noctua fans.
It's my favorite winter amp!
Cheers,
Jacques
Haha… it appears that I just have a slipping memory. One of the things that comes with requiring reading glasses and being middle age.
Haha… it appears that I just have a slipping memory. One of the things that comes with requiring reading glasses and being middle age.
I used to know the feeling!
Your next stage is having your hands tattooed - with your name and address...
had mine done back in 2002...haven't been lost since
:clown
I am - absoloootely!
I am not aware of any flaws with my AN4R - well, except for the heat they produce.
(So I still keep my previous AKSA amps for summer duty!)
Andy