audio-talk

I can feel a refresher course in 'how to use a 'scope' coming on....!
The last time I used one was around 1981....

Cool. I just measured my new baby, volume right down, across the speaker terminals (speakers connected) dvm measured 11-12mv. I guess the balancing pot would be a good place to start reducing this hum, bearing in mind Nicks advice to keep the D3as ac heated and my limited attempts to tidy up the 'ra...

Howsabout a 100R ww pot across the 2A3 filament w/wiper going to the top of that 770R resistor? You might be able to cancel some of the AC hum by twiddling the the pot to the null point. Works on the 3 stager I bought to Owster's. This is on my list of thinks to try- not done it before though. What...

Yes the heaters are centre tapped to audio ground. Its a right rats nest mind you! I could have routed the heater wires away from important bits an stuff... ah well, I'll live with it for now...!
Cheers
Thomas

I was planning on taking out the g3--r--anode connection and connecting g3 to the cathode, maybe later this week to see if I could hear anything different... thanks for the words from the wise, Andrew shed dweller!! Dave!! Cheers mate! You are welcome to give it a listen- beers in fridge waiting for...

Yep, cathode cap is a bundle of 'lytic, pp & pio (cheapo USSR) bypasses, total around 147uf. I'll work something out & try it out later...
Cheers
Thomas
ps no comments re my triode wiring of D3a?!

Ahh ok, just to clarify, the 47uf value results from use of the 2A3, not what the cap heater ct to ground value is. I might have a couple of electrolytics to try this- presumably the positive goes to the B+ end (dumb question now I think about it..!)
Cheers
Thomas

ac heaters throughout & there's no hum! Actually it does hum on start up then settles down to a level I have to put my ear to the speaker to hear... Speakers are Horning Perickles- after years nay decades of Lowther Bicors I impulse purchased these as they come with their own stonking great bass...

Thanks! - still burning in at the minute, & I'm still grinning too much to tinker- yet! But I'll try that capacitor- btw is that an 'ultrapath' or summat?! Just noticed my first mistakes.... Choke input reminds me I forgot to draw in the bleeder 22K 25w job in the schematic, just after the first...

Its big. Its heavy. Oh yes!
Circuit dia below (I hope)
All comments welcome!
I was going to re wire the D3a's g3 to cathode to see what that did later....

Dum or should that be Dumb?!
I'll take photo & post here!
As opposed to put in envelope....

Thomas

Excellent, thanks for that, I'll give the first one a go later. Have to elbow my daughter off her laptop for it as I use a mac...
Cheers Thomas

Even I can do that! PM me your address I can get it over to you later in the week (need to check tweak it first!). If I do some weight lifting exercises beforehand I'll bring the amp up to Eggy :D I'd still like to draw up & post the circuit here if only for hopefully some feedback/ suggestions....

Cheers Phil!
Umm - no scanner!
I wos wondering about drawing it with one of those posh 'computer programs'...

Good morning guys!- just finished my first breadboard, plugged it in and it didn't even spark up or disappear in a puff of smoke when I switched it on.. ! I'll happily admit I got most info for it off the 'net but I did set the cathode resistor with load lines an stuff (excellent tutorial here a whi...