Just posted a new design... a desktop headphone/speaker amp using 13EM7's. Nothing exotic this time, just a simple amp targeted at the beginner. And of course the PCB is also RED.
BTW, "Jonokuchi" refers to the lowest rank of sumo wrestlers. Roughly translated, it means "just beginning". At least I hope so, or I may be embarassed...
Jonokuchi desktop amp
Pete
Yup, it was engraved by FPE. The Japanese Kanji were a little bit of a pain... I had to turn it into an image file, then make it into HPGL to insert an HPGL engraving object. FPE asked me for the original image file to clean it up a bit.
It depends on how much I was willing to spend. The Edcors are great for the price, but are a little compromised at the extreme HF and LF. If cost were no object, I'd consider one of Sowter's headphone transformers, I think...
I personally don't like headphones since my head sweats too much to wear them for more than a few minutes at a time. I have built headphone amps for friends. If the physical apperance is not a factor I would look at the cheap Edcor XSE series. I have used them in amps making under 2 WPC for use with speakers or headphones. I measured the frequency response of an XSE15-8-5K at 1 watt. It goes from 8.3Hz to 45.9KHz with 50mA of current, and 16.6Hz to 45.6KHz with 80 mA (+/- 3db). Edcor doesn't make the 15 watt version in impedances higher than 5K, which is what I used in my 6EM7 amp. The 25 watt version is available in 7.6K but I haven't tried it.
Of course you can find several transformers to use with headphones if your budget allows.
Pete has a new red board.......how many watts can I crank out of this one......I already know the answer, since I built a similar amp a while back, but those who understand SE amps and understand Mr. Ohm already know too.
I've been looking for a spud PCB for a while now. I suppose it would be irresponsible for me to pass on this one. There was a nice lot of ten 13EM7 that just went by on eBay, too...Hello DIYers,
To avoid the $40.00 custom fee I had Edcor make 5 pairs of headphone transformers labeled GXSE3-300-5K.These are 3 watt 5000 ohm : 300 ohm headphone transformers. I have 3 different versions of head phone amplifiers that use this transformer. I requested the design to target 50 ma on the primary. At $40.00 a pair they are phenomenal. I also had Jack at Electra-Print make a pair of 8000 ohm : 300 ohm 3 watt transformers for about the same money as the five pairs of Edcor’s. The Electra-Prints sound nice too. BTW the Edcor’s have a UL tap.
Note headphones on your head draw much less than 0.1 watt. Tube amplifiers operating at such fractional watts produce vanishing levels of distortion.
A little sour cream with your spud?
DT
All just for fun!
To avoid the $40.00 custom fee I had Edcor make 5 pairs of headphone transformers labeled GXSE3-300-5K.These are 3 watt 5000 ohm : 300 ohm headphone transformers. I have 3 different versions of head phone amplifiers that use this transformer. I requested the design to target 50 ma on the primary. At $40.00 a pair they are phenomenal. I also had Jack at Electra-Print make a pair of 8000 ohm : 300 ohm 3 watt transformers for about the same money as the five pairs of Edcor’s. The Electra-Prints sound nice too. BTW the Edcor’s have a UL tap.
Note headphones on your head draw much less than 0.1 watt. Tube amplifiers operating at such fractional watts produce vanishing levels of distortion.
A little sour cream with your spud?
DT
All just for fun!
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