justinsweber Posted February 28, 2014 Share Posted February 28, 2014 I have my output iron on order for the 1626 SE with 32ohm and 600ohm taps... bing on the phones :-) Quote Link to comment Share on other sites More sharing options...
Deang Posted February 28, 2014 Share Posted February 28, 2014 Hi Justin, Is the SE version a headphone amp only? Quote Link to comment Share on other sites More sharing options...
joessportster Posted February 28, 2014 Author Share Posted February 28, 2014 Took this pic last night in the dark tubes a glowing nice and purty Quote Link to comment Share on other sites More sharing options...
bracurrie Posted February 28, 2014 Share Posted February 28, 2014 Took this pic last night in the dark tubes a glowing nice and purty Nothing nicer on a cold night than the warm glow of a tube amp with great music. It's also literally nice to have the heat. On the extreme end, I avoid using my Scott 222c, with its very hot rectifier, when its warm outside as it tends to trigger the AC more often. In the winter it helps keep the furnace from cycling on as often.Has anyone used cooling for tube amps? Quote Link to comment Share on other sites More sharing options...
joessportster Posted February 28, 2014 Author Share Posted February 28, 2014 At one time I owned Joule Electra Marquis OTL mono amps, and they would literally peel skin, I had them in a 12 X 16 room, and they would raise the temp in that room by close to 20 degrees. Every time I sat down to listen I would start sweating, They sounded good but I could not take the heat Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted March 2, 2014 Share Posted March 2, 2014 Headphone amplifier output impedance is certainly an important consideration. Some design for very low output impedances, though 32 ohms would not be unreasonable. One industry standard with which I'm familiar suggests 120 ohms, which I have also used when adopting an integrated amplifier for headphone use, but preferred by a significant margin (particulalrly in cases where max output power was in the range of just a couple of watts) using output transformer taps between 8 and 16 ohms -- with both my Grado and Sennheiser phones. Everyone is different though -- use and do what sounds best to you regardless of what anyone says to the contrary. Quote Link to comment Share on other sites More sharing options...
joessportster Posted March 2, 2014 Author Share Posted March 2, 2014 It's My-Fi....... Quote Link to comment Share on other sites More sharing options...
Deang Posted March 2, 2014 Share Posted March 2, 2014 I believe 32 ohms is the standard used for headphones intended to be connected to portable devices. Quote Link to comment Share on other sites More sharing options...
jcmusic Posted March 2, 2014 Share Posted March 2, 2014 Took this pic last night in the dark tubes a glowing nice and purtyNothing nicer on a cold night than the warm glow of a tube amp with great music. It's also literally nice to have the heat. On the extreme end, I avoid using my Scott 222c, with its very hot rectifier, when its warm outside as it tends to trigger the AC more often. In the winter it helps keep the furnace from cycling on as often.Has anyone used cooling for tube amps? I have a ceiling fan in my room that reduces the amps temp by 10 degrees on it's slowest setting... Quote Link to comment Share on other sites More sharing options...
joessportster Posted March 2, 2014 Author Share Posted March 2, 2014 Took this pic last night in the dark tubes a glowing nice and purtyNothing nicer on a cold night than the warm glow of a tube amp with great music. It's also literally nice to have the heat. On the extreme end, I avoid using my Scott 222c, with its very hot rectifier, when its warm outside as it tends to trigger the AC more often. In the winter it helps keep the furnace from cycling on as often.Has anyone used cooling for tube amps? I have a ceiling fan in my room that reduces the amps temp by 10 degrees on it's slowest setting... Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted March 2, 2014 Share Posted March 2, 2014 As stated, 32 ohms is not unreasonable. Some manufacturers design for impedances much lower. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted March 3, 2014 Share Posted March 3, 2014 Ive ordered iron for my 1st dedicated unit with impedances for 32 ohm for grados and alike and 600ohm for the wild stuff... I think 300 ohm was used previously with older designs. Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted March 4, 2014 Share Posted March 4, 2014 Justin: May I ask how you are calculating for those impedances? A number of valve amp designers install headphone jacks on their amplifiers which are connected to the existing output transformer's secondary taps - most commonly 4,8, or 16 ohms. Using those impedances, output voltage specs will often be provided for driving phones of different impedances, including those with impedances of a few to several hundred ohms. The headphone jack, where a common ground is used for the output transformer secondary ground connection, is often connected to the speaker out taps via a series resistor. The same thing can be done, by the way, to power a subwoofer off the same amp. One derives the subwoofer output off the output transformer secondaries, dropping it to a line level signal by way of a simple voltage divider. In other words, I would like to submit that you can build an extremely high quality, dedicated headphone amp using the same output transformers you would use for 4,8, or 16 ohm loudspeaker voice coils. Matching headphone impedance and amplifier output impedances is not exactly the same as what is common practice for loudspeakers. You can very easily use a good quality DPDT switch to toggle back and forth between the amp's speaker and head phone outputs in order to have a very capable amp for both purposes. Best of luck with your project! Great to see people building stuff! Quote Link to comment Share on other sites More sharing options...
joessportster Posted March 4, 2014 Author Share Posted March 4, 2014 You can very easily use a good quality DPDT switch to toggle back and forth between the amp's speaker and head phone outputs in order to have a very capable amp for both purposes. Best of luck with your project! Great to see people building stuff! Erik, Just curious why would you even need the switch,, unless it's simply to Mute one or the other if you had both speakers and headphones connected ?? Quote Link to comment Share on other sites More sharing options...
justinsweber Posted March 4, 2014 Share Posted March 4, 2014 I will not be using a voltage dividing network on this next amp. I wanted as simple a solution as possible… It might not work… but I’m hopeful it will. I didn’t want to take an output tap intended for a speaker and drive it down to be used for phones. The SE-84 takes that approach… I was tying a diffident method. I’ve seen this approach used… as I’m not a phones user I did not evaluate, but when this project is done and scoped… I’ll buy some to listen. The Darling circuit with 8ohm tap outputs ~.750mv… I will see when the transforms get here and are build what it will output given the new output impedances… the napkin math looks very promising but bench testing will tell. The hope is DHT, no feedback and no resistive network… strap the phones to the ¼” socket and call it good. I based my impedances on looking what several headphone manufactures spec for driving sig vs the phone freq response. Who knows… cant what makes it fun. Quote Link to comment Share on other sites More sharing options...
joessportster Posted March 9, 2014 Author Share Posted March 9, 2014 Justin your amp made my breakfast COLD, How am i supposed to eat with this thing calling to me ????? Blue man group, Pretty wild stuff Quote Link to comment Share on other sites More sharing options...
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