Finally everything connected and turned on🙂.
Adjusting the offset and quiescent current is not complicated and does not take long. Quiescent current is not adjusted in the original scheme, but I added that option mostly because I want to do some experiments with the replacement of transistors. So far I use IF170A, ZTX851/951 and 2SK1058/2SJ162. The current through IF170A is 1.2mA, through ZTX851/951 it is a little higher than in the original, about 18mA and through the output laterals is 140mA. ZTX851/951 are the only ones that are thermally loaded but meet the SOA graph. The output offset is only a few millivolts and is stable. The heatsink has dimensions of 20x8x4cm and satisfies even when listening loudly, the power supply voltage is +/-27V. So far I have only made basic measurements, for the more thorough ones I have to get a new sound card but the rectangular signal looks great on the scope, there is no noise or hum at the output. It works perfectly 😉 .
I won't say much about the sound because it has only been working since last night, but I must admit that I am satisfied and maybe even surprised by the sound quality. Kudos to JM Plantefeve, who I hope follows this topic.
Adjusting the offset and quiescent current is not complicated and does not take long. Quiescent current is not adjusted in the original scheme, but I added that option mostly because I want to do some experiments with the replacement of transistors. So far I use IF170A, ZTX851/951 and 2SK1058/2SJ162. The current through IF170A is 1.2mA, through ZTX851/951 it is a little higher than in the original, about 18mA and through the output laterals is 140mA. ZTX851/951 are the only ones that are thermally loaded but meet the SOA graph. The output offset is only a few millivolts and is stable. The heatsink has dimensions of 20x8x4cm and satisfies even when listening loudly, the power supply voltage is +/-27V. So far I have only made basic measurements, for the more thorough ones I have to get a new sound card but the rectangular signal looks great on the scope, there is no noise or hum at the output. It works perfectly 😉 .
I won't say much about the sound because it has only been working since last night, but I must admit that I am satisfied and maybe even surprised by the sound quality. Kudos to JM Plantefeve, who I hope follows this topic.
Attachments
Thank you,e_fortier 😉
The amplifier plays beautifully, I am satisfied with the sound considering the complexity of the amplifier. But it can't compete with A class amp like Le Monstre or JLH69 but it has the advantage of low quiescent current.
The next step is the installation of the regulator. It will be the same as in my Le Monstre. I'm really interested in the effect on the sound, especially with this type of amplifier.
The amplifier plays beautifully, I am satisfied with the sound considering the complexity of the amplifier. But it can't compete with A class amp like Le Monstre or JLH69 but it has the advantage of low quiescent current.
The next step is the installation of the regulator. It will be the same as in my Le Monstre. I'm really interested in the effect on the sound, especially with this type of amplifier.
Hello grunf,
I'm glad to see that the Cube and its listening pleasures are being exported to Croatia at least.
Yours sincerely, Jean-Marc.
I'm glad to see that the Cube and its listening pleasures are being exported to Croatia at least.
Yours sincerely, Jean-Marc.
Yesterday I started playing with driver transistors, to begin with instead of ZTX851/951 I inserted TTA006B/TTC011B. As far as the sound is concerned, there are no significant differences, the ZTX may have a slightly more open sound, the TTA/TTC a little better in bass 😉 .
The games continue🙂
The games continue🙂
Attachments
Finally, the regulators are close to being installed in the amplifier, I still have to thoroughly test and adjust them. The output voltage is +/-25V and the input voltage is +/-28V. It is Walt's Jung SR regulator, but modified for 10A (and more) current.
Attachments
Everything depends on the op amp, in this case it is OPA828 whose maximum operating voltage is 36V, although I would never keep it at maximum voltage.
Today I installed the regulators in the amplifier. And it sounds great, a total change of sound in all aspects. This is the third amp after JLH69 and Le Monstre that I have tried with these regulators and each time with the same result , with a smile on my face 🙂 .
Attachments
Until yesterday I was listening to Le Monstre because it sounds much better than 'cube', but since yesterday afternoon I don't know what to think anymore. Maybe it's the initial euphoria, but now it sounds better to me than Le Monstre. I have listened to a lot of amplifiers in my life, as I was also involved in sales for a while, but I always preferred the sound of the A class (it's all Mr. Pass's fault 🙂 ). But the 'cube' plays well enough as an A class.
The same regulator was used for all three amplifiers and each amp has its pluses and minuses, but these are minor differences. I am satisfied because I finally have a summer amplifier that does not require me to turn on the air conditioner.
The same regulator was used for all three amplifiers and each amp has its pluses and minuses, but these are minor differences. I am satisfied because I finally have a summer amplifier that does not require me to turn on the air conditioner.
I have to admit that in this case it was not initial euphoria, the amplifier with the regulators plays completely better and what is most important really well. That's why I decided to insert two more regulators to completely separate the channels and make a version of the amplifier with LSK389A instead of IF170A. The parts are all completed, the regulator PCB is finished and the amplifier PCB is still being drawn, I hope it will play soon 😉 .
So far I have tested the new regulators, now they still need to be fitted and connected. By the way, I will also change the input potentiometer from 50k to 10k, because in my system I drive the amplifier directly from the AD811 from the DAC. I hope that by the weekend there could be finished PCBs for the version with LSK389A so that it could be installed quickly.
Thank you all for your support. Mainly because this is the worst part of the year at work because I am an HVAC engineer.
.
Thank you all for your support. Mainly because this is the worst part of the year at work because I am an HVAC engineer.
.
The amplifier has been working in my audio system for 6 days. I must admit that it is even better with four regulators, although now the power supplies are separate for both channels. It is mostly heard in the lower part of the audio spectrum, I have to admit that I haven't heard such good bass in a long time considering that it is a low power amplifier. I'm currently listening CD Grace Jone's Hurricane Dub and I can't believe how good it sounds.. 😉
Attachments
Super neat homemade pcb's, Grunf!
You bang out boards almost as fast as JLCPCB!! 🤣
You bang out boards almost as fast as JLCPCB!! 🤣