Hello Wavebourn
Very good, it seem to be an easyer way to test an amp for phase intermodulation distortions.
Did you connected the amp to a dummy load or to a loudspeaker to do those squarewave tests ?
Thank
Bye
Gaetan
It was test of a tube driver connected to 3k load. I've just checked how first stage when added to the 2'nd stage, with feedback around both, affects performance. Before that I tested output tube of the driver and found it adequate:
Testing output tube stage of one channel: gyrator loaded triode strapped 6P15P.
Input signal: 4V P-P, output signal: 150V P-P, frequency: 300 KHz.
F-3db1=4 Hz, F-3dB2=900 KHz.
Is it enough, what do you think, to drive MOSFET follower?
Sadly I can't listen to your educated comments instead of my HT, it would be nice. Especially, when the 2'nd LTP stage is loaded on a current mirror, that can't be called resistive load.
So, I should keep trying to make my 6P1 Chinese special not the be the absolute worst she ever heard?
I changed the inputs to 6AY7's, cleaned up the PS a little. Careful adjustment I got the third harmonic distortion down into single digits. I have a pile of parts on hand to to, well basically change everything but the chassis transformers and sockets. 100 LED's to try the 'red light district" constant voltage bias. $2 why not? I can get about 6 W out of it into a 6 Ohm load. This is only my second tub amp I have played with. Total junk, but what better way to learn about load lines? Oh yea, different outputs but I can't remember what I bought. The project wound up on the shelf while I did a bunch of home improvement and cabinet work. I just got my office set up a few weeks ago and have been distracted learning solid state amps. I get dist.. Wow the sun just came out.
I changed the inputs to 6AY7's, cleaned up the PS a little. Careful adjustment I got the third harmonic distortion down into single digits. I have a pile of parts on hand to to, well basically change everything but the chassis transformers and sockets. 100 LED's to try the 'red light district" constant voltage bias. $2 why not? I can get about 6 W out of it into a 6 Ohm load. This is only my second tub amp I have played with. Total junk, but what better way to learn about load lines? Oh yea, different outputs but I can't remember what I bought. The project wound up on the shelf while I did a bunch of home improvement and cabinet work. I just got my office set up a few weeks ago and have been distracted learning solid state amps. I get dist.. Wow the sun just came out.
I notice mostly negatve comments about D'Self amplifiers , why? poor Design?
SqW looks good Wave , lots of feedback ...? .......................
Nope, excellent design. Just no mystery and no good story behind it. Engineering is boring, occultism is fascinating- go to a bookstore (if there are any left!), count the astronomy books, then count the astrology books.
Explanation of weak points does not mean negative comments. All topologies have strong points, and weak points. Otherwise the thread (and the whole DIY Audio) would be pointless.
SqW looks good Wave , lots of feedback ...? .......................
Did you ever read comments to pictures? Final driver stage was tested without any feedback, both stages were tested with feedback loop closed. Lots or not lots, it is your subjective matter, I don't play such silly games. As much as needed, without need of frequency compensation that affects end results.
I guess you missed the tongue in cheek moment .....
I guess you missed "Silly" word in my answer.
To be called "Vandal"?
I tried to contribute to Wiki page about "Tube Sound"; all my contributions were called "Vandalism" and removed. So, I put on Santana singing, "Let's the children play" and relaxed.
SANTANA Let The Children Play - YouTube
To be called "Vandal"?
I tried to contribute to Wiki page about "Tube Sound"; all my contributions were called "Vandalism" and removed.
I would consider that a compliment.
For the baby tube, I may build something fun like Louthers just to see, or something ultra efficient like Earl proponents. I have an old HK elite 300A that I am sure has better transformers, so if I am successful in modernizing the 6P1, I may do the same to the HK. It's a monster 12W. Still back office fun just to learn.
On the comment on the Self amp. He makes it very clear, he is describing amplifier design for commercial volume concepts, not the ultimate. He gladly shows Wilson mirrors, cascoding everything, and full symmetrical design. He is making a point that you don't need to start there. He does not seem overly fond of FETs, so not much discussion there either. It makes a very good place to start to understand design. It's a text book, not a cookbook. Unlike some textbooks, the sample circuit happens to work and is sold commercially. Try that with a few application guides out of old linear databooks! I don't understand more than 10% of it yet, so lots to do. Off the wall questions come to me, so I ask.
Looking over datasheets for modern small signal transistors, and seeing which are used in published designs:
I see the BC556/BC546 are pretty popular , 2SA970 looks pretty good, as do the MPSA06 series. I can't find a full spec on the 2SA1016 in my Rotel. I suspect it is older and a bit noisier. Any comments out there on modern BJT small signal transistors?
Thanks, quick look at the data sheet. Looks loke a handy middle of the range part. I noticed about the noise figures, every part is listed at some preferred current. I am guessing that is a hint as a good place to start if one wanted to use it.
Just realized, I gave away my "transistor tester" years ago. Guess I need to make something up to be able to match them with. My search for precision matched transistors is coming up with really low power devices, like 10mA and 5 V, usually SMT.
Just realized, I gave away my "transistor tester" years ago. Guess I need to make something up to be able to match them with. My search for precision matched transistors is coming up with really low power devices, like 10mA and 5 V, usually SMT.
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