"WHAMMY" Pass DIY headphone amp guide

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chrzr

Member
Joined 2021
Ok, forget the part about the different input voltage specs. I compared the specs listed on a few sites and Mouser somehow lists a max. input voltage of -23V for the L7915CP. This got me confused. According to the official datasheet it is -35V. So that should be ok.


I just checked all solder joints again - they seem to be ok. I also measured the voltage after unplugging from mains and the voltage between R13 and R14 drops down to -17V for a while until it discharges.

Something weird is going on here :confused:
 
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chrzr

Member
Joined 2021
Hmm.. I know that the regulator would output a higher voltage without load, but a difference of 10V seems quite high to me. Especially compared to the positive rail which is almost exactly at 17V.



But I also have to say that I have no deeper experience with regulators/this behavior. Could be a characteristic of the specific component.


I am just worried about damaging other components if I finish populating the board.
 
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JermNZ

Member
Joined 2016
6L6 said:
How hot are the regulator heatsinks? Hotter than 70? If that hot maybe I'd worry a little.

The regulators are working as designed. 15V + the Vfwd of the red LED, or about 17V.

If you want 15V rails, yes, Naked Reg.
Click to expand...

I measured them last night, they get up to about 55C and are settled after about 20 minutes.

This is at idle with no load, will it get much hotter during normal headphone or preamp use?
 
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JermNZ

Member
Joined 2016
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lawil

Member
Joined 2021
Martigane said:
For the 0.1uF, i used this one:
MKP4D031003C00JSSD WIMA | Mouser Belgique

For the 1k resistor, those ones should work well:
https://www.mouser.be/ProductDetail/Vishay-Dale/RN60D1001FB14/?qs=vEZPefDgUPkcBU7jWJvieQ==
Or
https://www.mouser.be/ProductDetail/Vishay-Dale/RN60C1001DRE6/?qs=2uw1TgnqFv4VHf2oHt50Pg==

For the transformer at the time I only found on digikey i used:
TE2261-ND
Click to expand...

PCB shipped! so just hopefully last question I have on the BOM list, which is the IEC inlet, can you recommend something here thats suitable for this amp? I indeed live in HK which is 220-240 VAC , i found something like AF-C10-SD on Mouser, is that ok? looks rather expensive but seems like has an integral fuse and a switch which is handy... Thanks!
 
rikiheck

rikiheck

Member
Joined 2020
6L6 said:
Class-A amps, being constant bias, are at their hottest at idle and actually cool down when driven hard, as that current is being given to the load.
Click to expand...
I was going to say that, but I thought maybe he was more worried about the regulators. I definitely have noticed with my Aleph 2s and, especially, 1.2s (which double as space heaters) that they are cooler the louder they play.
It's maybe worth saying that the Whammy does produce some serious heat, between the regulators and the MOSFETs. I made my last one with a wood chassis and left it on overnight to break in. I got up in the morning and the top had bowed, it was so hot! Time to drill more holes....
 
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rikiheck

rikiheck

Member
Joined 2020
Last edited:
ItsAllInMyHead

ItsAllInMyHead

Member
Joined 2019
Paid Member
lawil said:
PCB shipped! so just hopefully last question I have on the BOM list, which is the IEC inlet, can you recommend something here thats suitable for this amp? I indeed live in HK which is 220-240 VAC , i found something like AF-C10-SD on Mouser, is that ok? looks rather expensive but seems like has an integral fuse and a switch which is handy... Thanks!
Click to expand...

See post 3223. The Ohmite you selected above will also be functionally fine, but...

Again, with emphasis, if you're using the Hammond chassis, be sure the mounting configuration for the Ohmite will work for you. If you mount it a few mm off from the vertical center line...
 
C

chrzr

Member
Joined 2021
So I managed to finish my WHAMMY yesterday and I have to say that I am really pleased with it! I have only used it with my pair of AKG K340s until now and I really like how they sound with this amp! Can't wait to listen to my other headphones with it :D

No comparison to the Massdrop O2 + SDAC Combo I've used until now.



PXL_20210116_195730170.jpg


I still use the SDAC as input for the WHAMMY. I plan on upgrading to a different DAC in the future.



Thanks to Wayne for bringing this awesome design to life and thanks to 6L6 for the great building guide! :)
 
thomasnadeau

thomasnadeau

Member
Joined 2010
lawil said:
Hi Guys I just ordered the PCB from the store, and using the BOM list at the first few post of this thread to put together the parts (first time buying my own parts for a DIY project). Two items are unavailable on Mouser and if any of you can point me to a good substitute for those that would be great.

(2) .1UF C13, C23 .1uF 505-MKP2D031001FKA00

(6) RESQ R1 R2 R7 R10 R12 R14 1K 71-RN55D-F-1.0K

Also regarding the Transformer, ‎70065K‎ Talema Group LLC, is the only one I can find on Digikey/Mouser, are there any substitute on Mouser so everything can be on one site to avoid extra shipping cost? Much appreciated !
Click to expand...

Take a look at my "premium" build post here for some alternative part options.

https://www.diyaudio.com/forums/pas...-diy-headphone-amp-guide-303.html#post6382336
 
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