Thanks for the input, I wonder what everyone else is thinking.
Anyways, Recently I've found that the CFP has a special trick when it comes to frequency compensation. Doing this, you can adjust OLG without loading the LTP so much at high frequencies.
My heatsink now has a good fan to keep it cool. True class A.
- keantoken
Anyways, Recently I've found that the CFP has a special trick when it comes to frequency compensation. Doing this, you can adjust OLG without loading the LTP so much at high frequencies.
My heatsink now has a good fan to keep it cool. True class A.
- keantoken
Attachments
For the most part you are right - I could get something done before Christmas if I wanted to. I would rather screw around and blow a few fuses, thank you.
What I like about the Allison multiplier is that it is immune to thermal blowout - good for me because I don't want to screw around with thermal coupling quite yet. It's safe and should be workable.
The biggest problem is that I have no good reference to gauge how good this thing REALLY sounds. So while I will comment on the sound, it's actually hard to compare with what all else is in my house. Also, I can't manage to get the input right. I have an input impedance of around 37kohms, grounding is sub optimal (but there's no grounded outlet in my house anyways). The speaker enclosure is also nowhere near optimal, as I am using the hollow bottom of my mother's "great poets award (famous poets society)" silver cup.
Everything works fine with my portable CD player, since it's not grounded, but when I hook it up to my computer there is HF ringing (44.1KHz?) and pops and ticks while playing.
The only comparison I've made that I trust is that the treble is better than with anything else I have in the house. Other than that, I think my reference speaker is suspect - and it outperforms all other available junk by far.
- keantoken
What I like about the Allison multiplier is that it is immune to thermal blowout - good for me because I don't want to screw around with thermal coupling quite yet. It's safe and should be workable.
The biggest problem is that I have no good reference to gauge how good this thing REALLY sounds. So while I will comment on the sound, it's actually hard to compare with what all else is in my house. Also, I can't manage to get the input right. I have an input impedance of around 37kohms, grounding is sub optimal (but there's no grounded outlet in my house anyways). The speaker enclosure is also nowhere near optimal, as I am using the hollow bottom of my mother's "great poets award (famous poets society)" silver cup.
Everything works fine with my portable CD player, since it's not grounded, but when I hook it up to my computer there is HF ringing (44.1KHz?) and pops and ticks while playing.
The only comparison I've made that I trust is that the treble is better than with anything else I have in the house. Other than that, I think my reference speaker is suspect - and it outperforms all other available junk by far.
- keantoken
Clicks, pops and peeps are normal when connected to your computer and is due to the activity on the bus, power supply modulation and more. If you use headphones you will hear your mouse move, disc spin up and much more. Many think a computer is a good source of music, it is actually quite rubbish.
Nico
Nico
I am not sure how you judge this amplifiers performance with a 3" speaker in a shoe box. To me it is a waste of time.
Why not connect it to a half decent set of headphones at least you will get a better idea of its sound characteristics and whether you are moving in the right direction.
Nico
Why not connect it to a half decent set of headphones at least you will get a better idea of its sound characteristics and whether you are moving in the right direction.
Nico
Nico Ras said:
I use an X-Fi as my soundcard, which I listen to all my music from, and haven't heard any of these noises. I'm using different card for my experiments so I don't explode my old one. You are probably right. Hmmm...
Lumba Ogir said:keantoken,
I`m following the exciting development of this project with great interest.
Thank you.
Nico Ras said:
That is a good idea. I guess I can use a dummy load and connect my headphones in parallel with that. Might have to wait to buy some, though.
I will try to get my brother to take pictures of my whole setup so I can post them here...
Thanks everyone for your input and ideas.
- keantoken
Another advance!
I just completely rewired the LTP and VAS section.
Before I got extreme ear fatigue after prolonged listening. Much better! Before I was questioning my speakers, now I know that there was something wrong with my amp.
I changed the LTP devices to 2N5087's, and adjusted the CFP a little. It is oscillating very slightly, but not badly.
Now it sounds much clearer. I feel as if I've accomplished something!
Now it beats everything in my house, which is what I was aiming for.
Now it needs to get louder. I haven't been running it at full volume because some kind of glitch occurs at about -4V. I believe this can be remedied with some diodes to increase the C-B voltage on the Allison pair. However this will decrease the maximum output voltage. Things have gotten tight with the 12V rails...
EDIT: Nope, Allison glitching wasn't the problem. Bias current was too low. Nwo I have higher bias current, and it works up to around 20Vpk-pk output. It doesn't seems to be glitching or anything at that volume, so everything must be okay.
- keantoken
I just completely rewired the LTP and VAS section.
Before I got extreme ear fatigue after prolonged listening. Much better! Before I was questioning my speakers, now I know that there was something wrong with my amp.
I changed the LTP devices to 2N5087's, and adjusted the CFP a little. It is oscillating very slightly, but not badly.
Now it sounds much clearer. I feel as if I've accomplished something!
Now it beats everything in my house, which is what I was aiming for.
Now it needs to get louder. I haven't been running it at full volume because some kind of glitch occurs at about -4V. I believe this can be remedied with some diodes to increase the C-B voltage on the Allison pair. However this will decrease the maximum output voltage. Things have gotten tight with the 12V rails...
EDIT: Nope, Allison glitching wasn't the problem. Bias current was too low. Nwo I have higher bias current, and it works up to around 20Vpk-pk output. It doesn't seems to be glitching or anything at that volume, so everything must be okay.
- keantoken
Alright, I have been able to judge sound quality.
This amplifier beats everything in my house by far, even with the 3" speaker and it's shoebox enclosure.
This most obviously means that my speaker and enclosure are not so inferior as I have been thinking.
Since I've never heard anything better than this, I can't compare it to anything.
Now all I need is to make two channels and put them in a box with trafos, caps and a plugin cord. Hopefully I can also increase PSU voltage, allowing higher volume.
EDIT: Alright, after extended listening, I've found that the most noticeable difference between this amp and my other amplifiers is its ability to reproduce electronic music. It sounds true and clear, no matter what kind of treble you abuse it with. I never thought electronic music could made to sound "natural", but I have proven myself wrong. What sits on my bench right now, if the proof.
- keantoken
This amplifier beats everything in my house by far, even with the 3" speaker and it's shoebox enclosure.
This most obviously means that my speaker and enclosure are not so inferior as I have been thinking.
Since I've never heard anything better than this, I can't compare it to anything.
Now all I need is to make two channels and put them in a box with trafos, caps and a plugin cord. Hopefully I can also increase PSU voltage, allowing higher volume.
EDIT: Alright, after extended listening, I've found that the most noticeable difference between this amp and my other amplifiers is its ability to reproduce electronic music. It sounds true and clear, no matter what kind of treble you abuse it with. I never thought electronic music could made to sound "natural", but I have proven myself wrong. What sits on my bench right now, if the proof.
- keantoken
Pics!!!
Alright, here is my "workbench".
Here is my amp in its latest incarnation. The coax cable connection is my o'scope probe...
Zoomed out, you can see the speaker I'm using...
And here is the first working incarnation. If you're complaining about sound quality with the 3" speaker, try listening to this one!
- keantoken
Alright, here is my "workbench".
Here is my amp in its latest incarnation. The coax cable connection is my o'scope probe...
Zoomed out, you can see the speaker I'm using...
And here is the first working incarnation. If you're complaining about sound quality with the 3" speaker, try listening to this one!
- keantoken
I wouldn't elevate myself to "creative genius", but thank you!
Too much organization makes me feel insecure. I feel better if I can just snatch up the desired component immediately on impulse rather than going through a bunch of drawers...
Well now that I've made it work well, I don't know exactly what to do... Next I want to put in tone controls, volume of course, but that will have to wait until I have the parts necessary to make a case, PCB, etc. And to get that amount of money will take some time.
Of course, I could also take my chances at point-to-point soldering and see if I can put it in a scavenged case I already have handy. Still then I would need to pull a good trafo out of something...
Long-term listening will have to come after I have installed all output devices and can push an 8 ohm load at decent volume.
- keantoken
Too much organization makes me feel insecure. I feel better if I can just snatch up the desired component immediately on impulse rather than going through a bunch of drawers...
Well now that I've made it work well, I don't know exactly what to do... Next I want to put in tone controls, volume of course, but that will have to wait until I have the parts necessary to make a case, PCB, etc. And to get that amount of money will take some time.
Of course, I could also take my chances at point-to-point soldering and see if I can put it in a scavenged case I already have handy. Still then I would need to pull a good trafo out of something...
Long-term listening will have to come after I have installed all output devices and can push an 8 ohm load at decent volume.
- keantoken
This is the DIY spirit Keantoken....i thank you very much
From time to time appear nice things alike this one you have made.
My deep and noisy congratulations....it's.not usuall a diy inside the diy.... say...hands on work...there's DIY comments, DIY evaluations, DIY opinions, DIY calculations and other things..but hands on work is a rarity.
regards,
Carlos
From time to time appear nice things alike this one you have made.
My deep and noisy congratulations....it's.not usuall a diy inside the diy.... say...hands on work...there's DIY comments, DIY evaluations, DIY opinions, DIY calculations and other things..but hands on work is a rarity.
regards,
Carlos
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