Ah, I didn't know that it was 6L6 that posted the pics in the opening post.
No worries, and thank you!
Cheers.
No worries, and thank you!
Cheers.
you can always drill them holes for M25/1" bolts
even if circuit hardly alive afterwards, pleasure is immense whenever you do something so illogical
even if circuit hardly alive afterwards, pleasure is immense whenever you do something so illogical
Well, as someone who worked as a molecular biologist my entire scientific career and also 10 years as a Design for Six Sigma Master Black Belt, I struggle with the idea doing "illogical" things. 😛 🙂you can always drill them holes for M25/1" bolts
even if circuit hardly alive afterwards, pleasure is immense whenever you do something so illogical
^
"Six Sigma Master Black Belt"
LOL
Once upon a time, Yours Truly worked for a very large aircraft builder... Management decided to require ALL engineers to take a 48 hour course... for "efficiency" or something like that.
Someone calculated that if you knew the answers to all of the quizzes and tests, it could be done in 4 hours or less - the "online" course forced you to stay in each section for a minimum amount of time. So the idea was to start the test in its own window and leap frog from test to test as fast as possible. That way you could keep working or shop at eBay on the other windows.
So the engineers got cheat sheets and got it all done very quickly and efficiently. After all, if you knew the questions and answers, you knew the material.
We got the 48 hour training done in 4 hours.... now, that's a 20 Sigma Epsilon Alfa Diamond Belt!
I wonder if anyone up in management noticed how little effort was charged on that charge number. Surely some process guy complained but I figure the CPAs and CFO in HQ must have loved the numbers that came back from the R&D group. 😍
Even as most of us did that training charging overtime ( extended week ). Because we were pretty busy getting planes off the ground.
"Six Sigma Master Black Belt"
LOL
Once upon a time, Yours Truly worked for a very large aircraft builder... Management decided to require ALL engineers to take a 48 hour course... for "efficiency" or something like that.
Someone calculated that if you knew the answers to all of the quizzes and tests, it could be done in 4 hours or less - the "online" course forced you to stay in each section for a minimum amount of time. So the idea was to start the test in its own window and leap frog from test to test as fast as possible. That way you could keep working or shop at eBay on the other windows.
So the engineers got cheat sheets and got it all done very quickly and efficiently. After all, if you knew the questions and answers, you knew the material.
We got the 48 hour training done in 4 hours.... now, that's a 20 Sigma Epsilon Alfa Diamond Belt!
I wonder if anyone up in management noticed how little effort was charged on that charge number. Surely some process guy complained but I figure the CPAs and CFO in HQ must have loved the numbers that came back from the R&D group. 😍
Even as most of us did that training charging overtime ( extended week ). Because we were pretty busy getting planes off the ground.
Not yet. In fact, I have not fired it up yet. Watching a movie now. I prefer to double check everything the next morning.
It happened to me before, in the evening it (she) looks ok, but the next morning, you ask yourself.... 😉
So, more about the sound tomorrow.
Also, gotta build the other channel. Unfortunately, it will be uglier because I don't have the same heatsink...
Gee... it works 🙂
And it sounds nice too.
I was pleasantly surprised, especially by the bass. A Mini-Zen, sort of.
It gives an impression of listening to a much bigger and more powerful amp, that is, until you crank it up. In the car analogy, it reminds me of a feeling when I was driving a Chevrolet Spark, a small city car. Fast it was not, but had a very nice acceleration from 0-30 mp/h. After that, oh oh. But it was fun to drive, within its limits.
So, I adjusted the bias. Let it to warm up for an hour. Not much drift. Im my case,the heatsink was just lukewarm, even after an hour.
Next, I will try it with a 19V psu and 1.5 A current, because I have a feeling that the amp begs for it 😉
For those of you who are still in doubt, just build it 🙂
And it sounds nice too.
I was pleasantly surprised, especially by the bass. A Mini-Zen, sort of.
It gives an impression of listening to a much bigger and more powerful amp, that is, until you crank it up. In the car analogy, it reminds me of a feeling when I was driving a Chevrolet Spark, a small city car. Fast it was not, but had a very nice acceleration from 0-30 mp/h. After that, oh oh. But it was fun to drive, within its limits.
So, I adjusted the bias. Let it to warm up for an hour. Not much drift. Im my case,the heatsink was just lukewarm, even after an hour.
Next, I will try it with a 19V psu and 1.5 A current, because I have a feeling that the amp begs for it 😉
For those of you who are still in doubt, just build it 🙂
Update:
I tried the 19V supply and 1.5 A bias. Now it sings! 🙂
It was well worth it. I adjusted the voltage drop on the Source resistor at 750 mV. Initially it was around 720 mV, but as it heated up, it climbed up to around 750 mV and stayed there. The heatsink now served a purpose 🙂 It got hot but not too hot (I could keep my hand on it).
So, if your inductor and the heatsink can keep up with the higher voltage and current, I highly recommend it.
I just have to mention that my version was a bit different from the original (I accomodated the parts that I had in the drawer):
-Inductor: 90 mH, 0.8 ohm dcr
-Bigger heatsink
-IRFP240
-4700 uF output cap
-2.2. k and 7.5 k as feedback resistors
19V supply, 1.5 A bias
While testing, I used my phone as a source, and, as I could not get enough gain (and did not want to alter the feedback resistors) I took out a Frontend 2022 Preamp.
Wow!
I spend the evening listening to mono 🙂
Gotta build the other channel. And then compare it to MoFo...
I tried the 19V supply and 1.5 A bias. Now it sings! 🙂
It was well worth it. I adjusted the voltage drop on the Source resistor at 750 mV. Initially it was around 720 mV, but as it heated up, it climbed up to around 750 mV and stayed there. The heatsink now served a purpose 🙂 It got hot but not too hot (I could keep my hand on it).
So, if your inductor and the heatsink can keep up with the higher voltage and current, I highly recommend it.
I just have to mention that my version was a bit different from the original (I accomodated the parts that I had in the drawer):
-Inductor: 90 mH, 0.8 ohm dcr
-Bigger heatsink
-IRFP240
-4700 uF output cap
-2.2. k and 7.5 k as feedback resistors
19V supply, 1.5 A bias
While testing, I used my phone as a source, and, as I could not get enough gain (and did not want to alter the feedback resistors) I took out a Frontend 2022 Preamp.
Wow!
I spend the evening listening to mono 🙂
Gotta build the other channel. And then compare it to MoFo...
Magnifique! You can expect around half the THD and about 10 watts from that arrangement. 🙂
Hello Michael
What would be the THD at 10W into 8 ohm with 19V, 1.5A bias ?
At 12Vdc, the THD is 1% at 1W into 8 ohm.
I’m not one to obsess over THD, I’m just surprised but would be thrilled to see the power go from 1W to 10W at the same 1% THD.
Thanks
Eric
What would be the THD at 10W into 8 ohm with 19V, 1.5A bias ?
At 12Vdc, the THD is 1% at 1W into 8 ohm.
I’m not one to obsess over THD, I’m just surprised but would be thrilled to see the power go from 1W to 10W at the same 1% THD.
Thanks
Eric
I created a PCB so if anyone is interested please drop me a PM (not tested yet) and I’ll give you the Gerbers. It’s my 2nd PCB from scratch so constructive comments are welcome. PCB is 99mm x 48mm.
Thanks to NP for sharing his design 👍
Thanks to NP for sharing his design 👍