"WHAMMY" Pass DIY headphone amp guide

[emacs]

i ordered some components for modification.

6 different Opamp which included AD823


2 type of output transistor. 2013+313 was matched


RIFA PHE450 MKP 224 0.22UF 630V VS WIMA 0.22uF 300v
WIMA 1UF/100V MKS4 VS ERO MKT 250V 105 1UF
i dont know the 0.22uf and 1uf which type is better.


Here is a big question, i ordered 3 types of 220uf, but nichicon and SIC SAFCO are too big for installation, only Panasonic FC 220uf is suitable for this board.
Nichicon BP 220uf/50V got the ESR is 0.1324r @120Hz
SIC SAFCO 220uf/100V got the ESR is 0.148r @120Hz, bur the true value is 280uF, is it OK for use ?
May i know where should i install nichicon BP or SIC SAFCO is better as i can't install all of this on the board.

[6L6]

I don’t think there’s a much better electrolytic made than the FC. All the factory Pass Labs products are filled with them.

[chede]

+ 1

The Panasonic FC are my standard go-to electrolytic capacitors for a few years now. Have always been very happy with their performance.

Best regards, Claas

[emacs]

Thx 6L6 and chede solved my question. I will use FC in my board.

The 3300uf/50V i will use NipponChem KY series. I tested this cap then got the size is 3200uf and ESR is 0.0424R, the result is good.

[UltimateX86]

hello,
when you measure the distortion of a headphone amp, what are you using as a load and under which voltage?

[ashleytt]

Hi there. I'd like to know how to calculate the power outputs (mW) of Whammy to the phones I'm using: 14ohms, 46ohms, 250ohms and 300ohms. I'm using the default 17v rails and 60mA bias. TIA!

[rich1051414]

Originally Posted by ashleytt

Hi there. I'd like to know how to calculate the power outputs (mW) of Whammy to the phones I'm using: 14ohms, 46ohms, 250ohms and 300ohms. I'm using the default 17v rails and 60mA bias. TIA!

Power = Voltage * Current
Current = Voltage / Resistance
Therefore
Power(in watts) = Voltage^2 / Resistance
The typical max volume level is 2v, and going off that:

2v^2 / 14ohms = 286mW
2v^2 / 46 = 143mW
2v^2 / 250 = 16mW
2v^2 / 300 = 14mW
That would be peak, not RMS. Divide by the square root of 2 to get an approximation of the RMS, if that is what you want.

From what I understand, the 17v rail is mostly for the op amp, to allow it to swing further, to keep the output from dropping lower than the input without clipping.

[wayne]

I tested it into 32 Ohms and it is about 400 mW at low distortion. This will hurt your ears! It is capable of more than a watt into lower impedance loads.

[JamieMcC]

fwiw I spent an enjoyable couple of hours with the Whammy driving my 12" 100db 8 Ohm open baffle drivers and while they do benefit from a bit more oomph it was still very much an enjoyable listen with a clean & detailed presentation. The Whammy didn't seem to be stressed the heat sinks were no warmer than normal and the transformer (22v) stayed cool to the touch during that time.

Normally I use a 2W Set amp.

[ashleytt]

Thanks everyone! I won't be listening to high volume. Just want to have a sense of how the music I"m hearing related to the power outputs of the amp.