[alphaman]

If anyone here has check out new or vintage DIY projects -- in rags such as AudioXpress or Audio Electronics/Audio Amateur -- there were many low-power (3- 10 watt) amps, mostly using tubes, in the design.
However, rarely was there ever a mention of these SAME amps being suitable for headphones. Vintage integrated amps and receivers that featured a 'PHONES out normally had 100-400 ohms, 2-5 watt R's between the output stage (tube or trans) and 'PHONES jack. And the speaker terminals were, of course, a direct connection to that SAME output stage.
So the question is, for the low-power speaker amps, what type/value of R's should one use ? Given that cans like dt880-600 and other high-Z 'phones can benefit from "high" power?

 

[alphaman]

Here's what I mean ....

DIY project: A Beginner 6BQ5 SE Amplifier

The 6BQ5s—the power output tubes—are still easy to obtain, with many different brands to choose from. They deliver about 2W/ch in triode mode, or, about 5W in pentode mode.

https://gammaelectronics.xyz/ax_2008-10_6BQ5.html

 

[alphaman]

Here's another one ... maybe about 4W/ch. Intended for loudspeakers.
6A87 Current-Balanced, Push-Pull, Vacuum-Tube (valve) Amplifier--A DIY project

https://www.gammaelectronics.xyz/ax_5-2006_6A87.html

https://www.gammaelectronics.xyz/ax_5-2006_6A87.html

 

[Tjj226 Angel]

If anyone here has check out new or vintage DIY projects -- in rags such as AudioXpress or Audio Electronics/Audio Amateur -- there were many low-power (3- 10 watt) amps, mostly using tubes, in the design.
However, rarely was there ever a mention of these SAME amps being suitable for headphones. Vintage integrated amps and receivers that featured a 'PHONES out normally had 100-400 ohms, 2-5 watt R's between the output stage (tube or trans) and 'PHONES jack. And the speaker terminals were, of course, a direct connection to that SAME output stage.
So the question is, for the low-power speaker amps, what type/value of R's should one use ? Given that cans like dt880-600 and other high-Z 'phones can benefit from "high" power?

You really want to be using a resistor divider instead of a simple inline resistor. This page here goes into detail about what values you should use between your headphones and amplifier of choice.

https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm

 

[alphaman]

You really want to be using a resistor divider instead of a simple inline resistor. This page here goes into detail about what values you should use between your headphones and amplifier of choice.

https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm

Interesting ... HOWEVER, that dude Rob Robinette seems mostly concerned about using that divider with guitar amps (I think) ?????. Or other very low power amps. His R values seem very low (<10 ohms).

As I noted earlier: Vintage integrated amps and receivers that featured a 'PHONES out normally had 100-400 ohms, 2-5 watt R's between the output stage (tube or trans) and 'PHONES jack.
Look at the schematics of solid sate amp (integrated or receiver or even certain pwr amps with 'PHONES jack).
(110 w/ch)
http://www.thevintageknob.org/jvc-JM-S7.html
(40 w/ch)
https://www.hifiengine.com/manual_library/toshiba/sc-m15.shtml

That Toshiba vfet power amp from late 1979 has one 220-ohm/2W resistor/channel in series with OUT 'PHONES jack. And headphones back then were often in the 100s of ohms range with thicker coil wire.

Not sure ... I'll have to look into this a bit more about advantages of a divider .
EDIT:
Did come across this, which seems to support the case for divider :
https://diyaudioheaven.wordpress.com/headphones/power-amp-adapter/