audio-talk

Yep, things to try and a scope to look at bits too - won't come amiss.

Thanks Nick - I'll try that this evening. So, at 0 volts the GK should not be conducting anything and will be as silent as it can be.

I bet the amp still hums! - any takers?

Ha! its funny you should say that Nick because its 3-10 am and I can't sleep. Oh its nothing to do with the amplifier, but something very worrying at work that I have to put right. I can't sleep so I got up, and Horlicks in one hand and typing with the other: I thought that logging on here would hel...

2 down 386 to go ... Some of you will know that I am a fan of AC heating but I thought, let's try. I charged up a 6volt lead acid battery and used this to power the driver valves. howls of derisive laughter from the back row - of course it wasn't that. So let's disepense with some of the circuitry; ...

to create the virtual centre tap, I'd use 22 or 33 ohms - that sort of area.

I tried 'too large' (450mfd) and small (100) so to speak and now my reservoir cap remains 20Mfd, then 25Heneries of choke, then 200mfd of Polyprop. There is a 100mfd decoupler on the driver valve HT, before the anode choke. There are still quite a lot of 'could be' s I spose I'll just have to work m...

I like 'virtual centre tap'. I've just reaquainted myself with the schematic The Mk1 had hum pots so had a virtual cetre tap. Nowt wrong with that. And then according to Mk2 well no virtual centre tap and I note, cap and resistor are connected to cathode at +. I know I recommended that a while back ...

Have you got enough of the wood to make 30mm ply?

Yep, me neither ... and why not?!

But Philip, as electron flow in DC circuits is from negative to positive, why not put the resistor on the negative leg?

Aye, captain, I've stabilised the plasma flow in the spodraxulax core but I cannae hold the ... well you know what I mean.

Hum takes precedence now. If it is happy on Lwthers, it is a happy amp. Maybe then I can think of EHT.

'''''''A quick question for those more conversant with DC supplies than me: Is it better to put a 1R resistor in each leg of filament as opposed to a 2R in one leg or does it not make a jot of difference with DC? '''''' Oh dear, I worry about that too! & my solution is to halvethe resistance to ...

Well, now we have to consider HUM With the Sabs and a carpet there ain't nottin'worth giving the time of day. But With the dread Sidcup Screechers, the lowdown Lowthers, for all the glorious merits of oh so fast and micro detail I also get HUM. Can't hear it when the music is playing but, by George,...

Ah well, Guy was exceptionally kind and he let me keep the fuses for a long time. I tried the fuses on three different systems and most particularly on a preamp that is without doubt the best preamp / phono I have ever had the pleasure to listen to. No matter what I (and we - with a willing accompli...

That may preserve the aesthetics somewhat, Max. I've actually got a pair of those SCR teflons I want to try but I can't find them! But I am impressed with the Obligattos whereas before I thought if them as being merely 'passable'. Well actually I'm still a bit underwhelmed in a very non-scientific w...

Well Mike, the changes to the PSU are switches which, like fuses:-) do not in my experience, make a ha'ppence of difference to sound quality. Soldering wires instyead of merely being twisted together tends towards a growing sense of 'peace of mind' so that too was a good idea. Swapping a 5R4G for a ...