Here is a fun little amp that I have spent the last few days prototyping. ! watt output hence the fleapower designation. Been powered on for over 24 hours straight without any variation in operating point so I will say it is 100% stable even with slight difference in tube sections. When first powered the voltage at Q3 emitter will slowly rise as the tube warms so no large current surge, turn on thump, though you hear PS noise until the tube is fully conducting.
How does it sound of course is the first question most will ask. (WARNING BIASED OPINION!) It sounds great of course. Very good imaging and detail, overall balanced tone no harshness no shout and tight controlled bass inspite of being cap coupled.
Anyway quite enjoyable to listen to.
How does it sound of course is the first question most will ask. (WARNING BIASED OPINION!) It sounds great of course. Very good imaging and detail, overall balanced tone no harshness no shout and tight controlled bass inspite of being cap coupled.
Anyway quite enjoyable to listen to.
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Managed to do some testing on this. Programs used- RMAA6 and an oscilloscope program found here Soundcard Scope All tests were run with line out and line in volume set to 50% (changing either effects results) line out -> 10k pot -> amp input -> amp output -> 10k pot -> line in. Amp output set to 2Vrms @ 100Hz with 10ohm dummy loads using 10k pot in line out, line in adjusted to calibration level of RMAA6 using the second 10k pot. probably not the most accurate method I know but changing windows volume levels has quite an effect on results in RMAA6 for some reason. The soundcard isn't so great to begin with either, loopback test included as well. Used the oscilloscope program to confirm distortion and show square and triangle waves @ 1kHz, soundcard won't manage 10kHz waves.
TODO: Power supply needs some work as it's a bit sub par as can be seen by the amount of 120Hz noise in the tests, having it layed out on the table with wires all about I'm sure doesn't help either. This is just to give an idea of how well this little amp performs and it has more potential as it was something I put together in an evening using salvage parts from the junk bin.
TODO: Power supply needs some work as it's a bit sub par as can be seen by the amount of 120Hz noise in the tests, having it layed out on the table with wires all about I'm sure doesn't help either. This is just to give an idea of how well this little amp performs and it has more potential as it was something I put together in an evening using salvage parts from the junk bin.
I was looking at this, when checking your reply in another thread today. I'm not all that clever at attaching and
managing files myself but windows doesn't like it: (Audio Tests.zip invalid file)
It would be good to see what your test results were as you were obviously pleased with the result. Nice work.
managing files myself but windows doesn't like it: (Audio Tests.zip invalid file)
It would be good to see what your test results were as you were obviously pleased with the result. Nice work.
I'll second Ian's response-"windows doesn't like it".At All.!!!!!!
Would like to see them though.
6sn7a at 22Vdc/300uA.Yikes!
Would like to see them though.
6sn7a at 22Vdc/300uA.Yikes!
Hmm, it's a winrar archive, and seems to work fine opening with it. Maybe there was some corruption that windows zip folders can't deal with. Made this one with winzip, should work with the default windows archive program.
Upgraded the power transformer a few days ago along with a little more filtering and managed to clear up my 120Hz noise issue need to test it again.
Upgraded the power transformer a few days ago along with a little more filtering and managed to clear up my 120Hz noise issue need to test it again.
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There clearly are some issues with your soundcard setup. Things are working at 96 kHz only even though you're asking for 192. What are you using there? Keep in mind that even if the hardware actually supports both 192 kHz rec & pb (lesser ADCs tend to be 96k only), operation in shared mode requires that both input and output device format and sample rate be set up correctly by hand. Which is a bit of a nuisance. Alternatively, tell RMAA to use ASIO, with ASIO4All if need be - then things should run in exclusive mode, with automagic sample rate selection.
As far as levels go, it usually pays to stay a few dB short of maximum accepted input (possibly the same for output as well), especially with onboard codecs and other things that operate rail-to-rail.
As far as levels go, it usually pays to stay a few dB short of maximum accepted input (possibly the same for output as well), especially with onboard codecs and other things that operate rail-to-rail.
I managed to get some better tests using AISO4All. RMAA would only use aiso at 16/44.1k. Sadly it looks like my 120Hz demon is still lurking about. A couple of minor changes to the schematic. New transformer increased the voltage about 6 volts, however, 2 capacitors are all I've changed.
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