Paraglow 3?

[Ray P]

THought I would give a flavour of my next amp project.

Some of you may recall that I started with a stock Bottlehead Paraglow kit (which I reviewd in HiFi World a few years ago). I've gradually upgraded it with Cobalt output transformers, the Paraglow 2 kit (C4S, shunt regulation on the 6N1P), tentlab DC heater modules and various bits of silver etc. I think it sounds amazing driving my lowthers.

Anyway I've been talking to Paul Hynes and he's produced a constant current source/shunt regulator module for the 2A3 output tubes so my next project will be a reworking of the 'glows to incorporate these. I'll also take the opportunity to tidy up a few other things. Based on the improvements that applying this approach to the input tubes had this would seem to have good potential.

I'll post occasionally as I progress - at the moment I'm just sketching things out.

BTW, what a great guy Paul Hynes is, so helpful and accomodating.

Ray

[Andrew]

Hi Ray,

A well designed choke and cap based supply can be very good but a regulated one will be much better, I reckon.

I recall Paul's PX amp at the first EggFest that eventually drove his 212, he brought something that should have been better to second meet, but I didin't think it was, and blamed him using cathode followers. Now I now the first amp had a regulated supply. Was that the difference?

cheers,

-- Andrew

[Ray P]

So, here's one of Paul Hynes' SR5D modules that I'll be using in my next project. It comprises of a constant current source and shunt regulator on a single board. Max inpurt is 500V DC and it is adjustable to deliver upto 450V of regulated DC. Mine will be feeding a 2A3 output valve and will be delivering around 130mA (double the 2A3 bias current plus a little for losses).

Ray

[andrew Ivimey]

And that's a valve amp is it!?

I know it isn't because I can't see any of those glass things. So Ray, you are cheating!

[Andrew]

Hi Ray,

What's the IC's on the PCB? I'm always after new and interesting solid state devices that can live at >350v.

cheers,

-- Andrew

[Ray P]

Andrew (I) , cheating! - I'm not proud and I don't think silicon injections are banned by the world anti-doping organisation.

Anyway, isn't glass made from silicon.

Ray

[Paul Barker]

Hi Andrew,

the supply for the px4 amp was not only valve shunt regulated but capacitorless. It was the ultimate which I have ever made.

Oh and no sand.

[Paul Barker]

But it's a lot of heat power loss, expense and risk. I'm sure Paul Hines can do almost as well for less money risk and personal knowledge and effort required by the user.

[Ray P]

Paul Hynes modules cost in the region of £110 each.

They still waste a lot of energy as heat though, you need to mount the module on a heatsink of something like 0.6deg C/W. You dissipate something like 60-70W to get 2.4W to the speakers.

Ray