Another Darling
Posted: Thu Feb 23, 2017 12:01 pmSounds really good as a headphone amp too...
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Posted: Thu Feb 23, 2017 12:01 pmRe: Another Darling
Posted: Thu Feb 23, 2017 1:05 pmWow! That's jam packed that chassis.
Re: Another Darling
Posted: Thu Feb 23, 2017 2:07 pmIt's built on an enclosure that measures 7.4" x 7.4" x 2.5". I am pretty sure someone else has found a way to build it even smaller.
Re: Another Darling
Posted: Thu Feb 23, 2017 5:17 pmTwo 12B4As and 12AT7 (or 12DT8) work just as well, use the same DC voltages, resistors and OPTs, I built up that configuration a few years ago.
On the left is a 12B4A / 12DT8 SET, the "Darling Killer" built on and into a 4.5X7X3 inch cast aluminum Bud Box. The power supply (using an Antek 05T200) is built into the "tub", along with the electrolytic caps, choke and power switch and fuse, and the little green LED on the front. The amplifier circuit is all on the lid, and is connected to the PSU with a six wire "umbilical" This was designed and built so that I could try other amplifier designs on the existing PSU, with a minimum of wasted efforts. OPTs are the Triode TF103-48s, 5K to 8 ohms. Good for about 1.6WPC and sounds quite nice.
The circuit design is essentially identical to the "Darling" except for the tubes used. 12DT8 is equivalent to 12AT7, except that the filament is not center-tapped. Cheap tube, as it is not (yet) "audiophile approved"
/ed B
On the left is a 12B4A / 12DT8 SET, the "Darling Killer" built on and into a 4.5X7X3 inch cast aluminum Bud Box. The power supply (using an Antek 05T200) is built into the "tub", along with the electrolytic caps, choke and power switch and fuse, and the little green LED on the front. The amplifier circuit is all on the lid, and is connected to the PSU with a six wire "umbilical" This was designed and built so that I could try other amplifier designs on the existing PSU, with a minimum of wasted efforts. OPTs are the Triode TF103-48s, 5K to 8 ohms. Good for about 1.6WPC and sounds quite nice.
The circuit design is essentially identical to the "Darling" except for the tubes used. 12DT8 is equivalent to 12AT7, except that the filament is not center-tapped. Cheap tube, as it is not (yet) "audiophile approved"
/ed B
Re: Another Darling
Posted: Thu Feb 23, 2017 10:15 pmLooks awesome, Ed! Totally forgot about Antek toroids! I will keep them in mind next time I build a tiny amp.
Re: Another Darling
Posted: Fri Feb 24, 2017 4:53 amDid you drill or punch those holes? I've used those boxes before and my Greenlee's shattered the cover 
Re: Another Darling
Posted: Fri Feb 24, 2017 8:21 amI did both. I first punch the holes then drilled with a stepped bit to get the holes to match the size of the tube sockets. I did not run into any issues.
Re: Another Darling
Posted: Fri Feb 24, 2017 12:42 pmI tried to do 1-1/16" all in one shot. Maybe that was the problem 
Re: Another Darling
Posted: Sat Feb 25, 2017 9:30 amI later built up an EL84 / 7189 & 12AX7A SE version, looks nearly identical.
Different (300VAC/320VAC An-Tek toroid PT. Same Triode OPTs.
Lots more output power.
I never got around to photographing the inside view of the "tub" of either small amp, with all of the PSU components,
let's just say it is about as tightly packed as a sardine can
/ed B
Different (300VAC/320VAC An-Tek toroid PT. Same Triode OPTs.
Lots more output power.
I never got around to photographing the inside view of the "tub" of either small amp, with all of the PSU components,
let's just say it is about as tightly packed as a sardine can
/ed B