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"WHAMMY" Pass DIY headphone amp guide
"WHAMMY" Pass DIY headphone amp guide
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Old 6th December 2018, 10:39 PM   #861
cubicincher is offline cubicincher  Germany
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Default Whammy - which opamp?

Hello Murdoc,


I came back to the BB OPA 2604. In my opinion best all around performance.
Good bass and also in the mids / highs very good.


OPA 2134 also very nice. For me similar as good as the OPA 2604.



LME 49720 not my preferred one



AD817 single opamp / can't be used on the official Whammy-pcb!!!!
less bass than the others above, more mids and highs, sounds very detailed / analytic to me.
AD797 single opamp! not for use in the official WHAMMY!

I also used a LT opamp. But I have to check my partsbox which one it was.


Very important: check the pinouts of the opamps in the datasheets! Different pinout could become a disaster.



And it is many weeks back. Difficult to remember all the differences and to
describe them in words. Sorry!


Greets Dirk
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Old 6th December 2018, 10:40 PM   #862
wayne is offline wayne  United States
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"WHAMMY" Pass DIY headphone amp guide
I have built mine with the regs on red leds for + - 16.8 Volts. More voltage doesn't really gain much except heat in the outputs. The regulators don't do much work and then the Op Amp has good PSRR and mostly controls the whole thing.

The amp chip probably has the most effect as people have found. Good to see more successful builds.
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Old 7th December 2018, 12:17 AM   #863
labjr is offline labjr  United States
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Quote:
Originally Posted by cubicincher View Post
Hello labjr,


I tried different voltages on my WHAMMY-prototyp before the official pcb
came out. I have built a regulated PSU very similar to Waynes design.
I used the 'oldtimers' LM317 / LM337 to make the voltage adjustable. You can
see the blue trimmers on the photo.
My opinion is: it was very difficult for me to hear a difference in the sound
depending on the rail voltage. I tried between +-15 to +- 17.8 volts (depending on the opamp). But i am pretty sure you can measure a difference.

But I could hear a big difference in using different opamps at the inputstage.
Every opamp had its own 'character'.
And I am a friend of high rail voltages.

But that is my experience. Yours can be different.


My opinion is: build the WHAMMY and try it. You will like it.
And try different opamps....


Greetings from Dirk
I'm more curious about lowering the noise floor than using LM117/317 or raising the voltage.

Using 3-pin regulators off-piste: part 1
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Old 7th December 2018, 01:13 AM   #864
wayne is offline wayne  United States
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"WHAMMY" Pass DIY headphone amp guide
Here is the stock noise floor generally under one millionth of a volt. I cant even hear the 60 Hz as it was probably from my variac.
Attached Files
File Type: pdf Whammy_Noise.pdf (152.4 KB, 46 views)
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Old 7th December 2018, 01:17 AM   #865
6L6 is offline 6L6  United States
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"WHAMMY" Pass DIY headphone amp guide
Quote:
Originally Posted by labjr View Post
I'm more curious about lowering the noise floor than using LM117/317 or raising the voltage.
What noise floor? It's not PSU noise, the filtering on the stock circuit is incredibly good.


EDIT: Looks like Wayne already answered that.
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Old 7th December 2018, 03:18 AM   #866
labjr is offline labjr  United States
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Quote:
Originally Posted by wayne View Post
Here is the stock noise floor generally under one millionth of a volt. I cant even hear the 60 Hz as it was probably from my variac.
Thanks!
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Old 7th December 2018, 05:18 AM   #867
mercedese63 is offline mercedese63  United States
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Quote:
Originally Posted by cubicincher View Post
AD817 single opamp / can't be used on the official Whammy-pcb!!!!
less bass than the others above, more mids and highs, sounds very detailed / analytic to me.
AD797 single opamp! not for use in the official WHAMMY!
Single op-amps can be used in the WHAMMY with the appropriate adapter. Most DIP or SOIC adapters can easily be purchased from eBay.

Some of the best sounding op-amps are only available as singles.

Being notorious for oscillating, I wouldn't even consider using the AD797 for the WHAMMY or any other HA. It's happier in higher gain, low noise applications.
Even then PCB layout is crucial to getting the most from it.
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Old 10th December 2018, 03:29 AM   #868
birdbox is offline birdbox
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Can someone explain to a noob why C2 and C7 are not installed for any of the published builds. Thank you in advance,

Dan
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Old 10th December 2018, 05:22 AM   #869
wayne is offline wayne  United States
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"WHAMMY" Pass DIY headphone amp guide
They are not required I put them in thinking they might be needed for HF stability or controlling the top end roll off.
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Old 10th December 2018, 05:39 AM   #870
birdbox is offline birdbox
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Thank You Wayne! Super helpful to understand the original intent of those components. Side note, nice Bonanza!

Dan in Seattle
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