The PCB is $30
The kit with PCB and components are around $190, not including the chassis.
So $500 for finished product on Etsy or eBay? Its kind of high but probably a more reasonable markup than other amps.
$220 in parts including the Chassis.
Your paying for 3 - 5 hours of time in that assuming they are quick and they’ve gone through the pain of making the chassis cutouts a quick process.
$500 is not unreasonable.
2 Likes
And let’s not forget,l it’s $500 for an entry into a Pass Labs design, if that matters to you.
1 Like
A little update. After ~3 months of listening now, the OPA2134 is the op amp to have. Hands down. There are a few more ( OPA1612AQDRQ1, LM4562, Burston V6) that are supposed to be very good but for now I’m very happy so I won’t try those out anytime soon.
A few notes to make your build more successful:
-If you get an anodized/painted chassis, make sure to sand clean all contact surfaces including where the body of the pot sits against the chassis front. You want ground continuity between all surfaces and the ground nut. This insures a star ground pattern.
-Make sure to use shielded wire on the input. I had a high noise floor issue while using an unshielded 3 conductor braid. Swapped that out for a shielded Mogami mic cable and noise dropped to zero.
-Get a Neutrik plastic HP plug. Plastic being the key here - you don’t want the plug grounded to chassis.
-If using the Hammond case, either omit the plastic trim rings on the ends or, put them on the outside - not between the chassis endplates and the rest of the chassis. Again - proper grounding.
I priced out the BOM on Mouser and it comes out a few bucks more than just ordering through the DIY store.
And for those of you wondering - it’s a killer amp.
6 Likes
It is. A total impulse buy- I bought one that had already been built by someone with a Burson opamp.
7 Likes
Looks solid, any thoughts on it yet?
It’s a a neutral, moderately powerful, quiet, maybe warm amp with good dynamics. I’ve been enjoying it! I can’t say that it can compete with my Phonitor e, of course.
1 Like
Do you know what model the Burston is? V5/V6? Classic/Vivid?
Was looking at Bottlehead kits and stumbled on this…super stoked! Working to get PCB now.
2 Likes
This looks like a lot of fun, but I just bought a fa-12 
WHAMMY has always annoyed me with being too…what’s the word…meh. Mainly it’s got zero transients. Sounds like molasses. After swapping the caps on my LP and loving the results, I decided to do the same with WHAMMY (using all Audio Note caps in the signal path - PSU caps left untouched). Got all excited and turned it on and waited 4 days for the caps to burn in. Put on the cans and…meh. No change. WTF 
I figured I’d put it up for sale and suggest to a potential buyer that it’s best used with bright cans.
Then, on a lark I decided to swap op amps and see what happened. I had been using the OPA2107AP after trying out a bunch. I put in the op amp I liked the least (AD823 - my original notes read “not feeling it. lifeless. tired. don’t want to listen to it. dirty. constipated.”) just for shits and giggles and damn. It’s a new amp. The transients are not QUITE at the level of my modded LP but they’re way better than before. Maybe this is a good thing - it makes it a very easy amp to listen to for many hours at a time without fatigue. Staging/imaging is a lot better than before - way better than my modded Crack for example. Bass on HD600 seems more substantial than on my two other amps (modded LP and highly modded Crack). I guess I’ll go through all the op amps I have and re-evaluate with them.
Long story short, with two vastly different amps, Audio Note caps have made a substantial positive improvement. My go-to cap brand from now on. And, WHAMMY can be better than it is. Oh and also, it appears that the OPA2107AP imparts it’s own sound and isn’t transparent to other components.
3 Likes
i’m happy to read this. i have a whammy with a OPA2134 and I liked the amp a lot. That is until I heard a new release a particularly congested passage. Another DIY amp I have handles it with ease. The WHAMMY didn’t and I would love to get it to handle a really busy passage. Perhaps some opamp rolling will fix the potential to be congested.
which DIY amp handles with ease and Whammy doesnt? for omp amp rolling i recommend the sparkos labs one, really takes it to another lvl for my preferences
Neurochrome hpa-2
Whammy shot out!!
Father and Son?? All Pass!
After a dozen differnt op amps I left the BurrBrwn OPA2134 in the Whammy.
Alex
3 Likes
Nice amp hill!!
What’s the other red one?
1 Like
Its a very special DIY design from a friend “AGDR” over at the DIYAudio site. Its what the O2 might have been if there were ever a desktop non portable version of the O2.
Its well discussed in the DIY site.
Only a few of them were ever built by diy’ers.
3 X the current of the O2.
A expensive and not the easiest DIY project, due to small SMD parts.
AGDR has dropped of the planet and the pcbs are unobtainable.
Its very powerful amp that can drive most anything out there.
https://www.diyaudio.com/forums/headphone-systems/229934-version-o2-desktop-amp-oda.html
2 Likes
I added this Nelson Pass ACP + amp last week as well…so we have all three of PassLabs designs here…all good and different for sure.
4 Likes
Oh wow. A hidden gem for us non DIY’ers.
