Lockdown Valve Amp II
Posted: Sat Jul 18, 2020 11:45 am
Have been working on this for about a month.
He used afrormosia for the surround, and supplied me with an aluminium top plate that would complement the glow from the tubes. I think it has worked beautifully.
It’s the same idea as the version 1 of this circuit; just two stages of amplification.
The big glass globe pre/driver stage at the front is a pair of pre-war, mesh anode, Marconi MH4 high gain triodes. These use 150H chokes, as their anode load, which gives them twice as much driving voltage swing as the conventional resistor load would. This choke loading arrangement ensures that they will give powerful, low distortion drive to the KT120 output valves at the rear, which are ultralinear configured, to give 16W of single-ended power per channel.
Inside: In the context of the full system: As you can see, I like mid century retro.
Plinth is by our Ant (BTE Designs) I paid him to build me a proper hardwood plinth, as he can do a far better job of these things than I ever could, and I wanted this to be a more permanent addition to the system, with looks that suggest permanence, rather than ‘bodge,’ as RD used to call it.He used afrormosia for the surround, and supplied me with an aluminium top plate that would complement the glow from the tubes. I think it has worked beautifully.
It’s the same idea as the version 1 of this circuit; just two stages of amplification.
The big glass globe pre/driver stage at the front is a pair of pre-war, mesh anode, Marconi MH4 high gain triodes. These use 150H chokes, as their anode load, which gives them twice as much driving voltage swing as the conventional resistor load would. This choke loading arrangement ensures that they will give powerful, low distortion drive to the KT120 output valves at the rear, which are ultralinear configured, to give 16W of single-ended power per channel.
Inside: In the context of the full system: As you can see, I like mid century retro.