"WHAMMY" Pass DIY headphone amp guide

Got your address & Will send the boards tomorrow - yeah, there's just something about the ol' pugs that's enjoyable to drive - not so much the more modern sophisticated vehicles but that's the same for all, I think - this'll probably be the last fuel engine car for me - electric will be cheap, good and reliable in a couple of years - unless Emperor/President Andrews forces economics to go for an electric scooter!
 
I`ve got my Whammy up and running.
It plays music but the sound seem`s to be blurred / fuzzy.
Especially in high`s.
Someone have semilar experience with the AD823 in the whammy?



Have you checked the output stage is biased up properly and the dc offset is under 10mV etc?

What mosfets are you using?

Oscillation is another possibility.

Any loose connections anywhere?

Does the opamp have good electric contact on all pins etc.

Try some other rca cables too.
 
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AudioSan, et al:
Your responses to my Burson post challenged me to dig further into the opamp power supply. I decided to add a second stacked socket with the Burson-recommended 0.1 MKP cap mod. It also gave me a convenient place to measure the power supply voltages right at the opamp pins. I found that using only the red LED regulator references, the voltage at the pins was still well within the Burson spec:

Main Rails: +16.7 -16.8
Opamp Rails: +15.45 -15.53

That's about 1.25V drop across 47 ohms. 1.25/47 = .0266 (26.6 mA).

So, the Burson V6 Classic does draw more than specified, at least in the Whammy circuit.
 

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Have you checked the output stage is biased up properly and the dc offset is under 10mV etc?

What mosfets are you using?

Oscillation is another possibility.

Any loose connections anywhere?

Does the opamp have good electric contact on all pins etc.

Try some other rca cables too.


Bias -> ok
offset -> ok

How to check for Oscillations?
Is there an easy way? I have no scope only multimeter.
After cecking for oscillations i would check for connections -> much work with tiny SMD parts :magnify:

Mosfets are IRF9610 / 610
 
Check across the 47 Ohm resistor at the output of the opamp.
However most multimeters don't exceed 100kHz in bandwidth so may not detect it.

Do you hear any sign of power supply hum in your headphones?

Are you using the standard feedback resistor values?
Are you using 500 Ohm gate stoppers on the mosfets?

Check all the dumb stuff first, bad cables, bad connections,etc.

Have you installed the cap to chassis ground?
 
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Burson Vivid V6

Thanks to Burson Audio for the samples of Supreme Sound OpAmp Vivid V6.

Marking on the box: V6V-D-2
It came thoughtfully packaged with 2 DIP-8 adapters. I had already installed such an adaptor in my Whammy.



My build was with the PCBA from the diyaudio store. I sourced parts myself and stumbled many times with lots of rework.



Supply: +/- 15 V straight regulators. no LED or voltage divider
Input: Samsung Galaxy S9 plus. Volume two notches below maximum

Headphones: Sony MDR-7506


Gain with the Vivid V6 seems to be higher than with the baseline OPA2134PA. Gain matching was by ear. I realize this is not as accurate as with instrumentation. This was not a blind test. I heard the songs below with the OPA2134PA and then swapped it out for the Vivid V6, leaving everything else the same.



I had to move surrounding components a little. The footprint of the Vivid V6 is a little larger. Luckily, the box I used is big enough for height. so I'll let it stay a while.



(1) Track 1 Unaccompanied Cello Suite No. 1 in G Major, BWV 1007: I. Prélude

from Six Evolutions - Bach: Cello Suites, Yo-Yo Ma (2018)
(2) Track 4 The Four Seasons, Violin Concerto in F Minor, Op. 8 No. 4, RV 297 "Winter": II. Largo from Appassionato, Yo-Yo Ma (2007)

(3) and (4) The Hat and The Way I Am, Tracks 4 and 5 from Girls and Boys, Ingrid Michaelson (2006)
(5) Track 2 Künstliche Welten (Praha-Edit) from Künstliche Welten, Wolfsheim (2004)
(6) Track 10 How Deep Is the Ocean (How High Is the Sky) from Love Scenes, Diana Krall (1997)


The sound: there is more detail and more bass. Notes, and instruments are separately identifiable.



After this I continued to listen to many songs with the Vivid V6. In familiar songs, I was surprised, especially at the start and end of songs: sometimes I could discern extra vocals, instruments or notes.



That said, I think I am spoiled by ZenMod's Iron Pre. With that, I enjoy the music without paying attention to accuracy or anything else. With the Vivid V6, with my setup, to my ears, there seems to be something amiss. I don't know how else to say it.



In the words of our resident wise man "this is Entertainment - not Dialysis". It is good to have choices and even better to listen to a few.
 

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