"WHAMMY" Pass DIY headphone amp guide

[ernesternest]

I hear rumors of a possibility of a discrete from Nelson.

Oh, good to hear about. Just knew, that there was a paper, older one from Nelson, containing some general information. So this is good news. Timing from rumor to execution might be tempting for us greedies.

Whammy 5W class a power amp maybe? For 100db+ speaker. To have a low power alternative to ACA without lytics in order to power mids and tweeters in a multi way system. Just an idea - and by the way I really like my ACA.

 

[esgigt]

I hear rumors of a possibility of a discrete from Nelson.

Exciting.... Do "rumors" tell anything more, yet?

 

[flocchini]

Starting my build.

Because I intend to try Muses op amps and vol control and maybe Sparkos discrete should I just do the naked PSU?

Will be using the WHAMMY as pre to MoFo.

Thanks

Bob

 

[6L6]

That's a good idea. You'll loose a touch of voltage swing and trade it for a lot of reliability.

 

[flocchini]

Thanks Jim
Will keep you posted

 

[mbedwani]

Hi Guys, I’m I right in saying you are better off using shielded mic cable for the RCA inputs and headphone socket interconnects rather than braided standard wires. Is there really a difference in performance?

Mark.

 

[6L6]

Try a few different configurations and report your findings! We'd love to hear what you discover.

 

[mbedwani]

Hi Guys,

Need your help just finished the Amp and there seems to be something wrong my Right Channel. My Voltage rails are fine +16.7v & -16.7v. However my right channel is not putting out much power at all, and its square wave looks sick...

The only non-standard thing I have added is a feed from R10 & R14 to the v12 LED (power Switch) with a 4.7K limiting resistor on the R10 +V link side.

1Khz Signwave 1vp-p Right channel is ~2mV and Left is 100mV

1Khz Squarewave 1p-p - Right channel is 10mV and Left is 100mV




Any ideas where to look next, could this be an issue with my OP-AMP its a Burr-Brown OPA2134PA without the 100 pF caps.

Mark.

 

[seanwu]

I would like to ask a noob question.
What is the purpose of the capacitor between negative of RCA input jacket and ground?

 

[seanwu]

I don’t know how to edit previous so I post a new one.
I almost finish my WHAMMY with previous version PCB. Hook up the power socket and wire and I am done with this project. I tried to connect the power everything seems fine. I hear no noise of any kind. Just wondering if I have to install the capacitor between the negative of RCA and ground.

 

[Zen Mod]

antioscillation thingie

if Wayne put it there , just do the same

 

[chip_mk]

I think its function is to merge the case and the cable shield into seamless RF shield.

 

[mbedwani]

False alarm all good.

Ok I found the issue, I just noticed a hard to see x10 switch on the CRO leads, I must have knocked one to x10 rather that x1, I guess what threw me off was the dodgy looking square wave, Doh.

So now both channels look good and the square wave looks right now

My Beyer DT-1990pro's sound unbelievable on this thing, super happy




The FFT Graph looks good, 2nd 3rd and 4th harmonics @ 3 4 & 5Khz


Just before I tidy up the wireing


Front with power switch


Mark.

 

[Zen Mod]

is that shaft sort of remote ?

4m long , ditto to chair ?

 

[wayne]

The cap to chassis just provides a RF ground. Not required if it is silent but won’t hurt.

 

[seanwu]

The cap to chassis just provides a RF ground. Not required if it is silent but won’t hurt.

Thanks, Wayne. I will add the cap.

 

[mbedwani]

All done and closed up, great little proect, very happy with it.

 

[Dennis Hui]

Nice. That red chassis looks sharp!

 

[kpsthakur]

So far so good, nothing burnt [emoji4]. Cables tomorrow

 

[kpsthakur]

The power regulators get hot upto
58’ C here in Delhi ...unless with proper ventilation...I may have to drill lotta holes just above them in the chassis