tube fanatic Posted January 14, 2016 Share Posted January 14, 2016 I know of at least 2 forum members who are doing that and was wondering if there are others. It would be interesting to read comments about why you chose tubes to drive the phones instead of SS equipment. Maynard Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted January 14, 2016 Share Posted January 14, 2016 Had to pass on the pair I was wanting, but I'll be getting phones eventually and will be using them with my tube amp. Reasons? I already have it, surely it will sound good if my speaker pairings are any indication, and 3.5wpc is plenty of power for headphones. So why not? Quote Link to comment Share on other sites More sharing options...
justinsweber Posted January 14, 2016 Share Posted January 14, 2016 I have 3 amps that do. I do due to a dislike of SS devices and sonics. I chose tubes over SS for the same reasons I chose tubes in other amps. Seems there are 3 major camps for tubes and phones. 1 tube as input to mosfet, 2 tube power amp with transformers (road least traveled) and then otl. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted January 14, 2016 Share Posted January 14, 2016 Headphones only need 100mw to 600mw. 300mw should blow you away. 1 Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 15, 2016 Share Posted January 15, 2016 Would 12B4A be a reasonable choice for headphone tube amp? Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted January 15, 2016 Author Share Posted January 15, 2016 Would 12B4A be a reasonable choice for headphone tube amp? Yes, the 12B4 could be used although it's not the most linear triode around. Ask JP if he can run it in his simulator. If not, I can draw out some curves for you manually. As Justin pointed out, the power need with phones is so tiny that almost any tube could be suitable (the phones Michael mentioned above, if I recall correctly, claimed something like 100 db output with only 1 milliwatt!). The 6W6, triode strapped, is an excellent choice for low power use. Or, if you really want to do it on a budget, one of my Little Gem SET variants would do an excellent job as well. Maynard Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted January 15, 2016 Share Posted January 15, 2016 Would 12B4A be a reasonable choice for headphone tube amp? What is the headphone impedance? And what topology? I have had good luck using cheap line matching transformers for headphone power and tubes. http://www.parts-express.com/70v-10w-speaker-line-matching-transformer--300-040 I had a bunch of these laying around from a job I did. 1 watt into most headphones is more than plenty. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 15, 2016 Share Posted January 15, 2016 (edited) Hell, I don't even have headphones... I was just curious if 12B4A would be worthwhile in a headphone amplifier. I have had good luck using cheap line matching transformers for headphone power and tubes I think I may have one or two of those... Edited January 15, 2016 by mike stehr Quote Link to comment Share on other sites More sharing options...
Fjd Posted January 15, 2016 Share Posted January 15, 2016 (edited) Seems there are 3 major camps for tubes and phones. 1 tube as input to mosfet, 2 tube power amp with transformers (road least traveled) and then otl. I have examples of all three types; however, I tend to user them with certain other equipment as a "system" rather than decide upon individual preferences. My first example of tube/mosfet is the Pete Millett starving student hybrid. More information can be found at the link below to Pete's website. http://www.pmillett.com/starving.htm . Edited January 15, 2016 by Fjd Quote Link to comment Share on other sites More sharing options...
Fjd Posted January 15, 2016 Share Posted January 15, 2016 (edited) My headphone amplifier with output transformers is one that Dennis Had sells on eBay periodically. Here are excerpts of portions of the overview that was provided on the eBay ad. Stereo integrated vacuum tube headphone amplifier featuring dual triode 6SN7 (6BL7, 6BX7) tubes. The entire signal path is direct coupled. There are no coupling caps in the signal path. The output signal to the cans is directly derived from the special custom wound air-gaped output transformers. No resistors, zobel networks or switches in the signal path. I have listed a few of the highlights below: * Dual Triode 6SN7 tubes in class A single-ended zero feedback .. 6BL7 or 6BX7 tubes maybe used as well * Dual Pi-Network, Dual Filter Choke Power Supply * Vacuum Tube Rectification featuring the Tube Store 274B rectifier tube * Alps "Blue Velvet" volume control * Selectable two line inputs with a center position MUTE position * Dual Headphone Outputs * Precision non-inductive metal film resistors * Gold Plated RCA input jacks * EE Teflon silver stranded 19 strand hook up wiring * Custom Designed Air-Gap high impedance output transformers * 150% Duty Cycle CCS Power Transformer with internal copper strap * 100/120/240 VAC 50/60 Hz power transformers for any country of operation * .080 Aluminum chassis and bottom plate * Frequency response 12 Hz to 33 Khz + - 0 dB * Power Output at 32 ohms 1.125 watts . Edited January 15, 2016 by Fjd Quote Link to comment Share on other sites More sharing options...
Fjd Posted January 15, 2016 Share Posted January 15, 2016 (edited) The OTL headphone amplifier example is the Bottlehead Crack headphone amplifier. Here is a link to the Bottlehead site for additional information. http://bottlehead.com/product/crack-otl-headphone-amplifier-kit/ . Edited January 15, 2016 by Fjd Quote Link to comment Share on other sites More sharing options...
Fjd Posted January 15, 2016 Share Posted January 15, 2016 (edited) Finally, here is a little headphone amp that I have based on the diyaudioprojects website link below. The 12AU7 tube provides the voltage gain and the IRF510 Mosfet provides the current gain. The amp uses a LM317 adjustable linear voltage regulator as a constant current source (CCS) to move the Mosfet into the linear region and bias the amp into Class A operation. The headphone amp uses a 12v re-chargeable battery to operate. The circuit is a very simple design. http://diyaudioproje...-LM317-Headamp/ . Edited January 15, 2016 by Fjd Quote Link to comment Share on other sites More sharing options...
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