The Other 13E1 SE-OTL

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Ray P
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#31 Re: The Other 13E1 SE-OTL

Post by Ray P »

A parcel arrived from Poland today. They are audio grade transformers from Toroidy. Big one is 300VA 0-120V for B+. Smaller is 120VA 2 * 0-12V for 13E1 filaments.

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Ray P
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#32 Re: The Other 13E1 SE-OTL

Post by Ray P »

Steve has been trailblazing with his 13E1 OTL breadboard and has kindly shared a schematic of his 'final' version, which I plan to mostly follow;

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Because I already have the power supplies built, I will be using a different power supply arrangement, the same as that used for the Transcendent 300B SE-OTL;

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My power supply will feed both the 6H30pi (via the two anode resistors) and 13E1 valves. Do I need to make any tweaks to Steve's amplifier circuit to optimise it for the different power supply arrangement? Sorry to ask but I'm a painting by numbers guy with this sort of stuff.
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Ray P
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#33 Re: The Other 13E1 SE-OTL

Post by Ray P »

I've reworked the PCB that I designed for the 6C33C driver stage to suit Steve's 13E1 schematic;

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it can accommodate either traditional PCB valve sockets or the teflon CMC chassis mount ones. The section with the output caps is specific to my 15ohm Lowthers but can be removed for other arrangements, such as Steve's Fanes. Film caps are for Mundorf ZNs but others should fit. size is 84mm x 97mm (or 84mm x 70mm without the output section).
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Cressy Snr
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#34 Re: The Other 13E1 SE-OTL

Post by Cressy Snr »

Looks good!
Makes my breadboard shenanigans look like amateur hour. :lol:

I've put the 'Not OTL' 13E1 amp back in service in the system.
I'll give me 90% of the OTL's performance, whilst I'm building the real one.
I've beed granted permission to use it as long as it is put away on the kitchen table after use.
Lugging the thing up and down the stairs was getting to be a fatal accident waiting to happen.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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Ray P
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#35 Re: The Other 13E1 SE-OTL

Post by Ray P »

Cressy Snr wrote: Sun Jan 27, 2019 12:26 pm Looks good!
Thanks Steve. Electronic design I struggle with but physical/visualisation stuff I can do - probably why I'm a cartographer.

Anyway, I need to give it a final check and hope to order PCBs this evening.
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Ray P
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#36 Re: The Other 13E1 SE-OTL

Post by Ray P »

PCBs ordered. I'll send you a pair when they arrive Steve.
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#37 Re: The Other 13E1 SE-OTL

Post by Cressy Snr »

Ray P wrote: Sun Jan 27, 2019 8:42 pm PCBs ordered. I'll send you a pair when they arrive Steve.
Thanks Ray. You're a gent. :)
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Ray P
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#38 Re: The Other 13E1 SE-OTL

Post by Ray P »

After my sickly weekend I've been making some progress today, fitting the PS capacitor bank into the chassis and building some new filament supplies for the 6H30pi (because they're a lot hungrier than the 6SN7s). It's starting to take shape. I'll post some pictures IDC.
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#39 Re: The Other 13E1 SE-OTL

Post by Ray P »

Today's work. I've been reworking things a little for the 13E1 build, especially with the move from 6SN7 to 6H30pi so it feels a little like two steps back and one forward but its coming together now...

I'm doing the rework to take opportunities for layout improvements I've spotted so, for example, swapping the caps and choke positions keeps AC wiring shorter and more localised.

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RhythMick
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#40 Re: The Other 13E1 SE-OTL

Post by RhythMick »

Nice work, like the "box inside a box" approach.

Is the inner box aluminium ? Just wondered if it would shield better if it was copper/steel ? Don't shoot, just thinking out loud.
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Ray P
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#41 Re: The Other 13E1 SE-OTL

Post by Ray P »

RhythMick wrote: Wed Feb 06, 2019 4:35 pm Nice work, like the "box inside a box" approach.

Is the inner box aluminium ? Just wondered if it would shield better if it was copper/steel ? Don't shoot, just thinking out loud.
My approach isn't about shielding but about heat management. I started this project as a 6C33C build and they're notorious for running 'hot' so the idea was to build a chimney to promote a flow of air around the 6C33C bases, hence lots of surface area with the round slots, and to keep the worst of the heat out of the rest of the chassis to avoid shortening component life. My approach also enabes the use of fans to further enhance the cooling if required. The nice thing is that the structure of the chimney also facilitates mounting parts is a space efficient way and to avoid having too many fixings visible on the top of the chassis. The 13E1s should run a little cooler but the layout/approach is effective so I've stuck with it.
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RhythMick
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#42 Re: The Other 13E1 SE-OTL

Post by RhythMick »

Thanks Ray
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Ray P
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#43 Re: The Other 13E1 SE-OTL

Post by Ray P »

BTW, the sies of the 'chimney' are standard modushop parts, normally used as the side panels of the 'Galaxy' line.
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#44 Re: The Other 13E1 SE-OTL

Post by Ray P »

I've just spent a pleasant hour or so drilling the heatsinks (for the current sinks, but they'll also carry the power supply chokes). I would be assembling it all now if the plug taps I have on order weren't taking so long to arrive.
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#45 Re: The Other 13E1 SE-OTL

Post by Ray P »

Assembled and tested new filament supplies for the 6H30pi valves today. The 6H30pi filament is hungrier (825mA) than the 6SN7 so I chose to use supplies with more current headroom with a view to heat management and reliability.

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