European Triode Festival - ETF 2018 - pt I

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I love that ETF falls right around the American holiday of Thanksgiving as I am always so grateful for this event... people from different countries and cultures truly come together to construct these wild music reproduction systems that have no equal... it gives me hope... I struggle to find an equivalent in any other discipline... maybe if a bunch of people who build hot rods actually built a rat on site and then ran it around all weekend only to tear it up on Sunday?  that is as close as I can get... so grateful for the ideas and discussions and attitude and *passion* of ETF... you think you are going to get tired and crash and then an album, idea, sketch, or weirdo walks into the room and another hour or three is gone in a moment... and you find that you are kicking people out and shutting the system down so that you can get some semblance of sleep right as the sun is coming back up... 

so now on to this year's collaboration... truly several countries.... I had the idea very clearly at the end of last year's event... but I am still amazed that it actually came together.... 

the initial idea came from knowing that Tim, this year's host, had a single Western Electric 24 horn just like mine... and like all classic hifi "horse trading", he has tried to buy mine and I have tried to buy his... no dice... but he does not have the original 555 throat, so I wanted to share what I know about the sound of this strange and wonderful horn.. it is not quite multi-cell and not quite sectoral horn... it is unique.. and it sounds amazing... so I lugged the 555 and 19c receiver attachment (throat) to France (overhead bin) to mate with his mouth... this horn is often mated to the 594, but I really like what it shows about the midrange of the 555 as the horn is quite a bit longer with the 555's much small throat exit compared to the 594...

here Dietmar shows approximately where it needs trimming... bwahahaha.. I love Dietmar... and we did swap in his compression drivers for a bit... 2.5T in the gap!!  that is nuts.. and in the time it took me to swap drivers, Bjorn calculated that it is 4.5dB more efficient than the 555... so a quick rotation of the speaker level autoformers, and we were up and listening again... 

I also designed a "directional baffle" or open back short horn that I knew Tim could build in an hour or two... my oldest son built the prototype here in the New York shop in an afternoon... and I used an Altec bass guitar speaker (checked baggage) that everyone loves to hate on for the bass driver... I heard nothing but positive comments on the bass... quick, clean.. and shockingly deep.. I knew the front portion would be great as it is just a conical approximation of a horn that I have used for a decade.... something that I designed and built in Memphis that eventually became the old Wheel Fi midbass horn... but by loading the rear wave into the corner, and absorbing the upper frequencies with my daughter's coat and some foam, only the lowest notes were amplified by the corner... it worked out quite well.... and to top all of this off, Pete brought one of my field coil compression drivers and horns over from England.. not a lightweight job... 

so now on to the electronics... I always like to bring amplifiers that allow for tube swaps, and therefore tonal changes, with just a few twist of wire nuts... and this year was no different... I needed an amplifier that would meet the weight limit for checked bags.. and that is *the* reason I chose mono... so here is a small (cute?) mono amplifier that runs on one power supply... no stacked supply, direct coupled amplifier this year... and yes, dave almost killed me for the requirement of a 400V, 12mA bifilar nickel 1:1 interstage for a high plate resistance transmitting tube.. but at least I let the requirement of the swap to a mesh plate Bo slide (for this year!).... shown below is how we listened to it in New York before trip over... Eimac 15e driving Western Electric 205d... sadly, we ended up listening to so much music that we never even swapped in the 205d's in France!

so here is the back of the amplifier... note the interstage in the center with end bells... and all of the nickel chokes with brass channels.. and the strange dual output transformers in the top left of the photo... why two outputs? 

a scribble of the circuit... our incarnation comes, in reverse chronological order, from Martin Seddon, JC and Bae, Bjorn Kolbrecht, and Small (who is the likely inventor).. but in discussion with the Norwegians, it seems that Lars Lundahl may have used this arrangement in the late 50's!  always the way... everything has been done before... but it is a subtractive crossover... so it sums beautifully in the passband... 

the amplifier lit up with the 15e and this really wild "type 50" I have... it is a tall globe.. exactly the size and shape of the Western Electric 252... and box plates just like the 252... hmmmm.....

front end was similarly very simple and direct... nickel autoformer volume control... phono was two stage, direct coupled with LR equalization... table was a vintage tiny Sony provided by Schick, who also provided the tonearm... and of course the cart was Dave's field coil... (photo blatantly stolen from Holger, who loves me enough to not mind the theft)

this photo gives you an idea of what the 16th century salt cellar was like... Joe sitting in the chair... 

a perfect example of what the passion and knowledge of ETF is really like... in a discussion about the resonances of drivers and horns and their relation to loading, Bjorn just starts scribbling... 

next up are some photos of the wonderful location... and a few of the people who make it so wonderful!

peace,

me

here are a few more pics...