Hi guys
My boozehound clone is up and going! Albeit on a preliminary test-bed, but it fired up! The horrid buzzing I heard the first time was actually just a floating input
Lots of fuss about nothing! Either way, the 6v6s are pottering away happily at 260Vrms. It's surprisingly loud actually, really wasn't expecting it, or the low end! I've only got some crap Volvo speakers on it for the time being (not blowing up my Rainbows on testing!) but there is definitely punch in there.
There is no audible hum, and I mean it, with my ear against the speaker. There is also no volume control, so it's going 100% permanently until I put my stepped attenuator in there...so if it's not making noise we're good to go!
L
My boozehound clone is up and going! Albeit on a preliminary test-bed, but it fired up! The horrid buzzing I heard the first time was actually just a floating input
Lots of fuss about nothing! Either way, the 6v6s are pottering away happily at 260Vrms. It's surprisingly loud actually, really wasn't expecting it, or the low end! I've only got some crap Volvo speakers on it for the time being (not blowing up my Rainbows on testing!) but there is definitely punch in there.
There is no audible hum, and I mean it, with my ear against the speaker. There is also no volume control, so it's going 100% permanently until I put my stepped attenuator in there...so if it's not making noise we're good to go!
L
Mobile pics will have to suffice! My colleague has borrowed my 17-50 f2.8 :S so I can't take it with my SLR.
This is in benchtesting state, with the alu protection still in place and top not really bolted down
Gotta love the 'heatsink!' for the PI filter's resistor (B+ and C+ are chassismounted, as will this be eventually)
This is in benchtesting state, with the alu protection still in place and top not really bolted down
An externally hosted image should be here but it was not working when we last tested it.
Gotta love the 'heatsink!' for the PI filter's resistor (B+ and C+ are chassismounted, as will this be eventually)
An externally hosted image should be here but it was not working when we last tested it.
Long overdue an update!!
Pics are on :
http://www.flickr.com/photos/psychobiker/2486904094/in/set-72157604051618142/
Initially, I followed the schematic and used a CLC 'Pi' filter to smooth the rectified voltage. For a 7.2H inductor and 200uF secondary capacitor, an 8uF reservoir capacitor yielded 40.3V ripple on its terminals, and A+ here was 331V DC.
Changing to 16uF dropped the ripple to 20.9V, but A+ rose to 343V.
These levels of ripple were still unacceptable, although inaudible and inconsequential after the Pi filter's second filter cap. I decided for experiment's sake to change to a CRC filter, substituting the inductor for a 680R resistor in an effort to both cut ripple and eventually stabilise B+ voltage to nearer the 'sweet spot' of the 6V6s (~250V).
With that in place, 8uF reservoir cap prompted 16V ripple and 300V A+, 16uF's ripple was 10V and ~310V A+. This was nearing the target point.
Finding my original vintage capacitors annoyingly large hard to mount, I bought a 30uF capacitor and tried again. As expected, A+ rose to ~330V, but ripple had dropped to 5V, and B+ was bang on the sweet area of 248V with <10mV of ripple - evidently the filter was doing 'what it said on the tin'!
6V6s are happily plodding away at cathode 11V above ground...
Pics are on :
http://www.flickr.com/photos/psychobiker/2486904094/in/set-72157604051618142/
Initially, I followed the schematic and used a CLC 'Pi' filter to smooth the rectified voltage. For a 7.2H inductor and 200uF secondary capacitor, an 8uF reservoir capacitor yielded 40.3V ripple on its terminals, and A+ here was 331V DC.
Changing to 16uF dropped the ripple to 20.9V, but A+ rose to 343V.
These levels of ripple were still unacceptable, although inaudible and inconsequential after the Pi filter's second filter cap. I decided for experiment's sake to change to a CRC filter, substituting the inductor for a 680R resistor in an effort to both cut ripple and eventually stabilise B+ voltage to nearer the 'sweet spot' of the 6V6s (~250V).
With that in place, 8uF reservoir cap prompted 16V ripple and 300V A+, 16uF's ripple was 10V and ~310V A+. This was nearing the target point.
Finding my original vintage capacitors annoyingly large hard to mount, I bought a 30uF capacitor and tried again. As expected, A+ rose to ~330V, but ripple had dropped to 5V, and B+ was bang on the sweet area of 248V with <10mV of ripple - evidently the filter was doing 'what it said on the tin'!
6V6s are happily plodding away at cathode 11V above ground...
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