For sale is a custom Wavelength Audio SET amp using 45's as output tubes, designed and built by Gordon Rankin. Gordon built this for its first owner in response to his request for a great amp with small form factor based on the incredible 45 output tube. As you can see from the photos, Gordon named this the "Big Electron." It uses a pair of 45's for the output tubes, a single 6072A as the input tube and single rectifier (5R4GY or similar). It has great iron, using a pair of Magnequest TL404 output transformers that Gordon had in his private stash, and per Gordon is an amazing "3dB down at 8Hz and slams better than any 2A3 amp, and puts out around 3WPC" -- pretty amazing for a SET amp using only a pair of 45's! The amp's small form factor is a real plus but it does weigh in at almost 45lbs!
The amp has a switch to choose between 4 & 8 ohm speaker taps, a single pair of RCA inputs and the cream of the crop Penny & Giles (10k) volume control. Power supply is full of Blackgates, smoothed with big Teflon caps, the large plate chokes are Magnequest, and the coupling caps are Mundorf M Caps -- premium parts used throughout.
I have used this incredible amp as a stand alone stereo amp but also with a tubed preamp with the volume control maxed and experienced no degradation in sound. The amp drives my 96dB, 6 ohm impedance Audionote speakers superbly. Sensational mids and highs, with a nice tight and very significant bass for a 45 SET amp!
Given the flexibility of the great TL404 output transformers, Gordon also installed a high quality headphone jack. There is a switch on the headphone out for low and high (300ohm) impedance. With really efficient headphones with low impedance there is too much hum -- but with anything less efficient or higher impedance it's better. I would not say this is maximized for headphone listening, however.
I solved this issue with a speaker to headphone adapter called the Verto from Audiovalve -- not included in the sale -- but with everything from Hifiman HE-6 to AKG K1000 to various Audeze headphones, hum was almost completely gone and the sound is just incredible. Gordon also advised that the amp's speaker taps could be safely connected to drive headphones directly, as the amp is stable even with no speakers attached, so I would think the amp would be incredible driving HE6's directly.
The amp will come with a pair of 5V4G rectifiers, the 6072As seen in the pictures and really nice pair of curve tracer-matched 45s. Please note there is no guarantee given or implied on the tubes - consider them a gift. The amp also comes with an unmarked Lee Weiland-made Cryoparts power cord. Fantastic beefy sound. Consider it also a gift as part of your purchase.
Below are some notes that the original owner received from Gordon regarding the amp as he put the final finishing touches on it:
“Hum pots finalized... 0.312mv left, 0.322mv right which is really low even on the headphone output. Oh FYI here are some specs and they are killer.... 4/8 ohm taps from 6Hz to 60Khz -3dB, -1dB from 12-28KHz Wattage at 1% was 2W and 10% was 2.8W.
32 ohm same freq stuff 0.1% wattage was 1.16W
300 ohm same freq stuff 0.1% wattage was a 0.99W”
The big globe 274B tube is too large and would bump into the side of the power transformer, some of the ’skinner’ or straight bottle 274B’s should be fine. There are a ton of others to choose from. I think there is a 274B in a straight bottle, but that might be a rebranded 5Y3 which sounds ok. This is a 2A rectifier circuit so the 5U4 and the larger Mullard stuff will NOT work. The GZ34 has a little too high of voltage for my liking as it puts the 45 tubes at about 10.5W dissipation which is more than their rating. These others keep it down around 9.2W-9.4W. Amazing enough the 5V4A which is an indirectly heated version of the 5Y3 sounds really good and the most quiet of the bunch. 5R4GY should be a great match also!”
PLEASE DO NOT use EML tubes in the amp. First they tend to blow up big time and they have taken out 34 of my amps and I don't even direct couple. Those are not 45 tubes, they are some sort of hybrid. Just because the filament is 1.5A at 2.5V does not make it a 45 tube. There are a ton of better tubes out there and real 45's are easy to come by.”
I will say that I have used EML Globe 45s with no problem - but I thought it best to included this warning from the amp's maker himself.
Gordon's custom amps start at $7,500 and go up from there depending upon options selected. This amp comes with everything you see pictured except the brass footers you can spy in one of the pictures. It comes with the nice isolating black feet you see in the full pictures of the bottom. There are some circular scuffs on the bottom plate where the brass footers had been installed, other than that the amp looks and sounds simply incredible. Rated 8/10 for scuffs and the fact I am the second owner.
Buyer to pay shipping and fees. Cheers and thanks for looking.