In Reply to: RE: From the Ohms law formulas... posted by soulbrass on July 10, 2017 at 18:21:16:
Can be viewed from different perspectives. If you tend to listen at low volume levels, low output headphone amps will serve the purpose well but if you tend to listen at higher volume levels, the lower output is an issue.
A 470 ohm resistor in line is a bit high but, from a design point, you don't know what headphones were used to test the output or what type of volume restriction was used in its design. A headphone output jack could very well be designed with safety in mind and the power output limited so high output levels can be avoided (and human hearing protected).
People could also plug in in-ear monitors, which are very sensitive, and the 470 ohm resistor makes perfect sense with these type of headphones. A user could also choose Audeze LCD-3 headphones and the output would not be sufficient with those headphones.
If you drop that resistor to 47 ohms, like I suggested, the output of approximately 1 watt can be very high power for many headphones. If you own the aforementioned Audeze headphones, 1 watt may still be a little low powered.
It is a matter of what is enough. I own a Schiit Lyr 2 headphone amp and it is capable of 6 watts/ch at 32 ohms and that is a lot. The output circuit has a sensing circuit to prevent over powering headphones but the amp is capable of lots of power with every headphone that I've tried. The owners manual makes a statement about taking care with volume settings due to the high power.
I have several vintage pieces of audio gear that uses a load reducing resistor like your amp uses and I don't recall any of them using a value as high as 470 ohms. All of these vintage amps have much higher power output than 12 watts/ch.
As a result, I was a little surprised by the 470 ohm rating for the power reducing resistor. Considering the fact that its capable of 12 watts into 6 ohms, dropping the output with a 470 ohm resistor is a bit of overkill but like I already said you do not know what they were designing for.
Have you tried any headphones with this amp? What type of volume level are you used to listening to?
Ed
Life is analog...digital is just samples thereof
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Follow Ups
- "Drove with ease".... - EdAInWestOC 05:16:04 07/11/17 (3)
- RE: "Drove with ease".... - soulbrass 05:53:23 07/12/17 (2)
- It wouldn't be worth the loss if you omitted a resistor... - EdAInWestOC 11:28:37 07/12/17 (1)
- RE: It wouldn't be worth the loss if you omitted a resistor... - PakProtector 01:41:48 07/16/17 (0)