02-10-2017, 12:14 PM
Thanks Gents. Praise indeed coming from two fettler's of renown.
Been mucking about this morning testing it yet again, not because it needs testing really but more to familiarise myself with the test gear I have. I'm trying out a few PC based spectrum analyser's and a program called REW, which is used for testing room acoustics ( it has a very good sig gen). I have a Marconi SA, which isnt working at present, but to be honest for what I use a SA for, Rtspect and Anaprof (both free) are more than adequate and easier to use for my purposes. I have two decent interfaces I use for recording, so have appropiated one for use with testing. I just need to knock up an attenuator so I don't fry the IP.
Previously I'd tested this amp at 1khz THD but tested it today at 100hz, 6khz, 10k and 20k, both sine and square. I tried to measure N and hum, but it's very low, my meter a Fluke bench DMM is having trouble getting a fix on it. I'll try a valve AC meter and my Marconi dist meter next. The sq wave looks good, though better at lower frequencies. Next I'm going to test for intermodulation distortion which I've not done before.
Like I said above, this testing is more about learning and having a fun twidling knobs than trying to improve the amp, though I have found a few things that I've tweaked. EG hum was quite bad so I re-routed the IP sig cable which improved things immensely.
I'll do another video soon as I know a few of you like to see progress. Thanks for your interest, Andy.
Been mucking about this morning testing it yet again, not because it needs testing really but more to familiarise myself with the test gear I have. I'm trying out a few PC based spectrum analyser's and a program called REW, which is used for testing room acoustics ( it has a very good sig gen). I have a Marconi SA, which isnt working at present, but to be honest for what I use a SA for, Rtspect and Anaprof (both free) are more than adequate and easier to use for my purposes. I have two decent interfaces I use for recording, so have appropiated one for use with testing. I just need to knock up an attenuator so I don't fry the IP.
Previously I'd tested this amp at 1khz THD but tested it today at 100hz, 6khz, 10k and 20k, both sine and square. I tried to measure N and hum, but it's very low, my meter a Fluke bench DMM is having trouble getting a fix on it. I'll try a valve AC meter and my Marconi dist meter next. The sq wave looks good, though better at lower frequencies. Next I'm going to test for intermodulation distortion which I've not done before.
Like I said above, this testing is more about learning and having a fun twidling knobs than trying to improve the amp, though I have found a few things that I've tweaked. EG hum was quite bad so I re-routed the IP sig cable which improved things immensely.
I'll do another video soon as I know a few of you like to see progress. Thanks for your interest, Andy.
