This amp is from the original Moth Audio lineage, and was Craig Uthus' attempt at maximising the moth si2a3 design for headphones usage while still maintaining its stellar performance as a speaker SET amp. This is one of only 5 iterations that Craig built - this specific amp is 5/5. Craig soon committed full time to Eddie Current, and the 5 moth si2a3/45H that he custom built represent some of his finest work with transformer DC-coupled DHT SET designs. Tube rectified with the 5AR4 and input tubes consisting of the 6J5, which is a single triode version of the 6SN7, same exact performance but much better cost. Output iron, PS input choke, and PS transformer all custom Electra-print.
It can operate both 45 tubes and 2a3 tubes with the flip of the switch. Features volt meters that show the amount of bias current running through the tube, and in essence, function as mini tube testers that help diagnosing if a particular tube goes bad. Plus they look cool.
It can drive both headphones and speakers. Headphone wise can accomodate a wide range of impedances including IEM's, grados, sennheisers, orthodynamics, K340, and even the K1000. Speaker taps on back to drive most speakers classified as "hi-efficiency", such as lowthers and fostex single drivers, as well as horn designs like vintage klipsch and altec. 45 output is around 2W and 2a3 output is around 3W.
The external chassis houses the power transformer and heaters, eliminating all source of hum and noise that the stock si2a3's exhibit, especially over low impedance headphones. Grados are dead silent in terms of operational noise and hum with the volume pot maxxed out, and even my shure se530's exhibit no hum whatsoever, with just a tiny bit of tube hiss.
Features various improvements such as CCS load and LED bias for the input tubes, snubber caps across the filament diodes to block switching hash and noise, and increase of bias current through 6J5 to operate in a more linear region within tube curve.
Feel free to google "moth si2a3/45H", but forewarning that the majority of stuff is probably me
I feel an interest check is appropriate due to the rarity of the amp, and the outstanding sonics it offers, as well as it being able to provide double duty as a world class headphone and speaker amp. There are not many 2a3/45 DHT SET headphone/speaker amp designs currently out there that have a similar pedigree to that of a Craig Uthus me thinks. Will include mullard 5AR4 rectifier tube and various 6J5 input tubes - you can source your own 2a3 or 45's, I have Emission Labs 2a3 and 45 solid plates for extra if you wish, the EML's are the best for this amp based on my rolling experience.
Prefer NA, but will consider international as long as accomodations can be met. Feel free to PM with questions and offers to be considered.
with eml 45 tubes
external power supply chassis
barely noticeable "ding" in chassis from original shipment
It can operate both 45 tubes and 2a3 tubes with the flip of the switch. Features volt meters that show the amount of bias current running through the tube, and in essence, function as mini tube testers that help diagnosing if a particular tube goes bad. Plus they look cool.
It can drive both headphones and speakers. Headphone wise can accomodate a wide range of impedances including IEM's, grados, sennheisers, orthodynamics, K340, and even the K1000. Speaker taps on back to drive most speakers classified as "hi-efficiency", such as lowthers and fostex single drivers, as well as horn designs like vintage klipsch and altec. 45 output is around 2W and 2a3 output is around 3W.
The external chassis houses the power transformer and heaters, eliminating all source of hum and noise that the stock si2a3's exhibit, especially over low impedance headphones. Grados are dead silent in terms of operational noise and hum with the volume pot maxxed out, and even my shure se530's exhibit no hum whatsoever, with just a tiny bit of tube hiss.
Features various improvements such as CCS load and LED bias for the input tubes, snubber caps across the filament diodes to block switching hash and noise, and increase of bias current through 6J5 to operate in a more linear region within tube curve.
Feel free to google "moth si2a3/45H", but forewarning that the majority of stuff is probably me
I feel an interest check is appropriate due to the rarity of the amp, and the outstanding sonics it offers, as well as it being able to provide double duty as a world class headphone and speaker amp. There are not many 2a3/45 DHT SET headphone/speaker amp designs currently out there that have a similar pedigree to that of a Craig Uthus me thinks. Will include mullard 5AR4 rectifier tube and various 6J5 input tubes - you can source your own 2a3 or 45's, I have Emission Labs 2a3 and 45 solid plates for extra if you wish, the EML's are the best for this amp based on my rolling experience.
Prefer NA, but will consider international as long as accomodations can be met. Feel free to PM with questions and offers to be considered.
with eml 45 tubes
external power supply chassis
barely noticeable "ding" in chassis from original shipment
