WHAMMY DIY Build

[Sythrix]

I have decided to build the WHAMMY DIY Headphone amp, as it looks fairly straightforward. I got interested in the project after finding the PCB on the diyAudio store. The build guide is a little bare-bones in some aspects, but there's schematics, pictures and it's detailed enough that you can get through without too much trouble. What's unfortunate is that there are some items, like the volume knob, RCA L & R inputs, and a few other things that simply aren't listed in the BOM. Also, there's a small amount of drilling and cutting that needs to go on here, for the holes and the IEC inlet. I have already talked to my uncle, who has a drill press and the know-how to help me out with those aspects, so when I finish the PCB, I'll go to his house and finish up the case and anything else.

If you want access to my project on Mouser, let me know and I will send you the link, however I make no guarantee of its completeness. You need to crosscheck what you're going to do with what is on the BOM... for instance, I still don't know if the capacitor he coupled to safety ground was on the BOM or if that's just something I need to discover myself. Besides Mouser, I ordered the transformer from Digi-Key and the RCA inputs from Performance Audio (Left and Right). Performance Audio also has really good prices on some of their bulk cable, which is where I got mine for this project as well as the cables I'll be making in a couple months or so.

(All photos taken with a Sony α65 and a Sigma 70mm F/2.8 EX DG Macro lens, except the first, which was taken with the Sony DT 18-135mm lens).

I had attached the Transformer and wired the voltage before beginning documentation of this experience.

Closer shot.

Rear of the PCB

The build guide calls for assembling the power supply portion first, in order to test it, so I've laid out the smallest components for soldering.

...and here we see a group of happy little leads...

...and now they'll be happy as future bridges or whatnot. (PCB has not been cleaned yet).

Now I'm working my way up to the taller components. There's actually a lot of room on this PCB so i'm not too worried about future soldering of the main circuit.

I was worried about not having any nuts for the opposite side, but it turns out I have a bunch of screws that are the perfect size to create their own threads in the heatsinks, so problem solved! I'm using some of the TIM I used on one of my old video cards, from when I changed out the paste.

Ready to go! (EDIT: Forgot to mention I changed to slightly smaller headed screws, because the initial ones were too wide).

That's it for now. I'll upload more as I finish. I hope to have the main board done this week, with the case being drilled out next week along with final completion.

Let me know if you have any questions or if you want to point out a concern. We're all prone to miss something now and again.

Also, if you're doing anything like this yourself, don't hesitate to speak as I'd love to hear about it!

Until next time.

 

[Sythrix]

I'm back again to deliver an update on my progress:

EDIT: As noted by JoelN further on in the thread, the resistors at R9, R10, R13 and R14 should not be installed in this configuration as is shown in the pictures (they were later removed). Please omit them if you plan to build this same configuration.

Testing the power supply was my next move, so I wired the IEC Inlet and started on wiring the AC for the PCB.

Ready to test.

LEDs alight! Everything looks good so far.

Voltage is close to 17V on both, which is exactly where it should be. At this point I got out my thermal camera and took some pictures, out of curiosity.

Nothing too exciting... but I think I'll look again when I get to the testing phase. I changed the filter on the last image to see if it would give me better detail, but except for the Mosfets without a load, there isn't much to look at here.

All the resistors laid out. I think you all get the idea of how the back looks by now, so I won't keep showing it or the soldering until the very end.

Then I added the capacitors, optocouplers and the op-amp socket (I'm not going to fit an op-amp til the end, as I'm not sure what I want to use yet).

I went with IRF Mosfets for the main circuit. The procedure was the same as the ones for the power supply.

...and that's it for the PCB component layout. At least for now. I plan to visit my uncle next week to get the case drilled, as well as cut out a rectangle for the IEC inlet. I'll probably put some holes for venting over the Mosfets as well. I've never been comfortable with sealing all my components inside of a metal box to cook.

Once again, if you have any questions or want to comment on something, let us know what you're thinking.

Thanks for looking and see you next week.

 

[Sythrix]

Back again, after a longer hiatus than I had anticipated. Getting the drilling done was easy enough, but I lost a lot of motivation afterwards and just didn't feel like working on it. Fast forward to today and I'm only a few steps away from the testing stage.

Me and my uncle got the plates all drilled out. It's not quite perfect, but it's good enough for DIY. We accidentally went one size too large on the stepped bit for the headphone jack, but it didn't turn out to be a big deal.

At first, attacking the shielding to separate it was a real chore. I didn't understand quite how to do it and started with a flat-head screwdriver, as I has seen others do. Turns out the tip of an old multi-meter probe was a far better tool. You can actually unravel them if you take it in steps and have a precise tool.

After soldering both the signal wire and the shield, I heat-shrunk them all closed and did the other side in red.

I continued the process for the headphone jack.

I asked in the official WHAMMY forums on diyAudio and was told that the capacitor that is shunted from the RCAs to ground is a non-critical value, so I used an old one, which had previously turned out to be too big for one of my other projects. I'm hoping I won't have any issues.

Creating the threads with these screws turned out to be a much bigger chore than I had anticipated. The screws themselves kept wanting to strip and the aluminum on this panel proved to be far more formidable that it first appeared, making turns difficult.

In order to fit everything and have it away from the transformer on the PCB, we had to stack the RCAs like this in order to have the IEC Inlet in an appropriate position.

Back panel complete.

Had to widen the screw holes on the front panel headphone jack and use a nut on the inside in order get it straight. Unfortunately, the initial measurements were slightly crooked, so it required tweaking.

...and that's it for now. Next time I will probably finish. I'm going to include some thermal shots of the amp in action after it has warmed up (providing it works, of course), so that should be interesting.

 

[Wombat]

I have decided to build the WHAMMY DIY Headphone amp, as it looks fairly straightforward. I got interested in the project after finding the PCB on the diyAudio store. The build guide is a little bare-bones in some aspects, but there's schematics, pictures and it's detailed enough that you can get through without too much trouble. What's unfortunate is that there are some items, like the volume knob, RCA L & R inputs, and a few other things that simply aren't listed in the BOM. Also, there's a small amount of drilling and cutting that needs to go on here, for the holes and the IEC inlet. I have already talked to my uncle, who has a drill press and the know-how to help me out with those aspects, so when I finish the PCB, I'll go to his house and finish up the case and anything else.

If you want access to my project on Mouser, let me know and I will send you the link, however I make no guarantee of its completeness. You need to crosscheck what you're going to do with what is on the BOM... for instance, I still don't know if the capacitor he coupled to safety ground was on the BOM or if that's just something I need to discover myself. Besides Mouser, I ordered the transformer from Digi-Key and the RCA inputs from Performance Audio (Left and Right). Performance Audio also has really good prices some of their bulk cable, which is where I got mine for this project as well as the cables I'll be making in a couple months or so.

(All photos taken with a Sony α65 and a Sigma 70mm F/2.8 EX DG Macro lens, except the first, which was taken with the Sony DT 18-135mm lens).

View attachment 15550
I had attached the Transformer and wired the voltage before beginning documentation of this experience.


View attachment 15552
Closer shot.

View attachment 15553
Rear of the PCB

View attachment 15554

View attachment 15555
The build guide calls for assembling the power supply portion first, in order to test it, so I've laid out the smallest components for soldering.

View attachment 15556 ...and here we see a group of happy little leads...

View attachment 15557
...and now they'll be happy as future bridges or whatnot. (PCB has not been cleaned yet).

View attachment 15558
Now I'm working my way up to the taller components. There's actually a lot of room on this PCB so i'm not too worried about future soldering of the main circuit.

View attachment 15559
I was worried about not having any nuts for the opposite side, but it turns out I have a bunch of screws that are the perfect size to create their own threads in the heatsinks, so problem solved! I'm using some of the TIM I used on one of my old video cards, from when I changed out the paste.

View attachment 15560
Ready to go! (EDIT: Forgot to mention I changed to slightly smaller headed screws, because the initial ones were too wide).

View attachment 15561

View attachment 15562

View attachment 15563


That's it for now. I'll upload more as I finish. I hope to have the main board done this week, with the case being drilled out next week along with final completion.

Let me know if you have any questions or if you want to point out a concern. We're all prone to miss something now and again.

Also, if you're doing anything like this yourself, don't hesitate to speak as I'd love to hear about it!

Until next time.

Great to see a hands-on DIY build project on ASR. Thanks for sharing.

 

[Sythrix]

Back again with the finish.

Ran into some unexpected problems this time. The first of which was that I realized the outer screws holding the jacks in place were going to run directly into the outer perimeter of the case, preventing closure.

EDIT: (Forgot to mention that all photos in this post and the previous post were taken with my new camera, the Panasonic DC-G9 and the Panasonic Leica 45mm F2.8 Macro Lens, except the last image, which was taken with the Panasonic Leica 25mm F1.4 Lens, and the thermals which were taken with a Seek Thermal RevealPro.)

I ground them down with a Dremel. Unfortunately, this was my first time doing this, so it's not pretty (it's on the inside, so who cares). I wish you guys could have seen the sparks coming off the steel screw though! Too bad I didn't get a video of that.

New Problem! The board doesn't fit into the case. See the left (white) jack down there? It's in the way because we set it too low when drilling the holes. I have the beginning marks of the area I need to cut on the PCB. That's right, I have to cut into the PCB. By some miraculous fool's luck, there is nothing important there (It's just a part of the extensive grounding plane, it won't be missed) except maybe the standoff hole... but I'm not using them, so it's time to cut!

Measured and marked.

Confirmed there is nothing there. No traces.

I don't trust myself, so I put a bunch of tape to protect the nearby components in case of a slip.

Little crooked. Doesn't matter.

Now it fits!

Just have to wire the inputs and outputs. Even with an appropriate tool, pulling the shielding braid out gets old... fast.

Also remembered I still needed to fit an op-amp, so I went for my tried and true LME49720.

Input wired.

Output wired.

Ready for testing! I didn't screw in the self-tapping screws yet, because they can only be put in so many times before they strip out their own holes... hence the crap-tastic tape job... onwards!

Test commencing! But there's a problem. I keep hearing crackling and popping. I'm devastated. However, I remember from the WHAMMY thread on diyAudio that they recommend testing many different op-amps if the one you choose doesn't work well. I have an OPA2134, so I put it in instead. It fixed the issue!

EDIT: Forgot to mention, the DC offset was measured and was negligible: less than 1 mV.

The thermal images are next. I took these at various intervals of the test. There wasn't that much variation between the temps over an hour. I've chosen some of the most interesting pics. They progress from earliest (around 10 minutes) to oldest (about an hour).

Op-amp.

The power supply MOSFETs got up to about this temperature after ~30 minutes and stayed there.

This was the hottest that the other MOSFETs got.

An overhead shot without the center reticle.

The op-amp never got much higher than this. Since the OPA2134 max recommended temp is 85C (185F), I decided it was fine and didn't need a heatsink. There are some op-amps that operate at their upper limit (17V) when used in this design. Make sure you confirm what the op-amp can handle before using it. If it does approach its limit, you may have to use a heatsink on the op-amp or a different one altogether.

After testing, it was time to put it together and be done. I screwed on the panels, the volume knob, and put on some rubber feet. There's a slight gap where the backplate meets the top panel (it must have gotten warped during drilling or another process). It's not too bad though. Unfortunately, this amp doesn't really look new or shiny. There's a bunch of scratches all over it from mishaps during the build. It doesn't bother me, but maybe I'll get a blue Sharpie one day and try to touch things up a little.

Overall I'm really happy with it and am listening to it as I write this. It sounds fantastic, but that's just subjectivity. There's no hiss or anything I can hear, so it seems like a really good, clean amp. It also has a lot more range with the volume than my Millet Butte (and not so much gain), so I don't have to feather the knob on the low end to get even (but not deafening) sound. It gets more than loud enough when required. Also, there's only a slight blip when the unit powers on, unlike the Butte; which is loud enough that I started unplugging my headphones before powering it on.

If you've been thinking about building one, I say go for it! Feel free to shoot me any questions, or you can head over to the official forum at diyAudio, where there's a proverbial army of people who have already built this, ready to answer questions.

I'll leave you with a glamour shot...

Thanks for looking! Until the next time I find something to build...

 

[Sal1950]

Thanks for all the words and photos of your journey!
Hope it exceeds all your expectations.

 

[Sythrix]

Thanks for all the words and photos of your journey!
Hope it exceeds all your expectations.

Thanks, so far it has. The increased range and sensible gain were worth it alone over what I was using before. Have to spend more time with it, but for now there’s no downsides I can see!

 

[DonH56]

Cool stuff!

I would ground the input shield cap right near the connectors. Shorter RF path for better EMI suppression, and keeps from routing the cap connection around the AC input (seems risque').

 

[Sythrix]

Cool stuff!

I would ground the input shield cap right near the connectors. Shorter RF path for better EMI suppression, and keeps from routing the cap connection around the AC input (seems risque').

Thanks for the tip! As of right now I can't hear anything at all coming from the amp unless I start playing something. As far as safety, I made sure to insulate everything well, but I understand the concern. Looking at the pictures again it does look a little risque, but the cap is above the IEC inlet and everything is insulated down to the connection point... However, if I open it up again in the near future I'll be sure to get out my drill and move it to the other side. Right now I'm kind of tired of building...

 

[Sythrix]

I would ground the input shield cap right near the connectors. Shorter RF path for better EMI suppression, and keeps from routing the cap connection around the AC input (seems risque')

Hey, to bother you again real quick...

I did what you said and secured it right next to the RCA inputs, so that's done.

I noticed with some old, super sensitive Sennheiser IEMs I have that there is a slight hiss. I can't hear it at all with my DT 1990s or my M1060s, even if I crank it all the way up. Anyways, I was wondering for future reference, if I even wanted to use IEMs or very sensitive headphones, what might be the cause of that? The transformer? The MOSFETs? Something else?

It's not a big deal at the moment, just wondering.

 

[DonH56]

Hum is often from the power mains or power supply (assuming a linear power supply and not a SMPS). Hiss is usually just the noise floor of the amplifier and may be hard to track down. Could just be the driver itself...

 

[Sythrix]

Hum is often from the power mains or power supply (assuming a linear power supply and not a SMPS). Hiss is usually just the noise floor of the amplifier and may be hard to track down. Could just be the driver itself...

OK, well it's definitely not a hum, so I'm guessing it's the noise floor, as you say. Even then, it's not exceptionally loud and when I start playing music with the IEMs, I can no longer hear it.

I'm kind of an optimizer when it comes to things I can customize or fine tune, but I'm guessing this is just the nature of the amp based on what you're saying. Since I'm getting an incredibly clean output on everything I actually plan on using, I don't think I'll let it bother me.

 

[Wombat]

Hey, to bother you again real quick...

I did what you said and secured it right next to the RCA inputs, so that's done.

I noticed with some old, super sensitive Sennheiser IEMs I have that there is a slight hiss. I can't hear it at all with my DT 1990s or my M1060s, even if I crank it all the way up. Anyways, I was wondering for future reference, if I even wanted to use IEMs or very sensitive headphones, what might be the cause of that? The transformer? The MOSFETs? Something else?

It's not a big deal at the moment, just wondering.

Lower output impedance may help. This can be achieved with a suitable in-line attenuator if the amp has enough spare gain.

I can't vouch for this but it is cheap enough to try: https://www.audioadvisor.com/prodinfo.asp?number=IFEARBUD

 

[amirm]

What a great read. I had missed the thread before. Thanks for all the hard work and congrats on the build.

 

[amirm]

What was the total cost by the way?

 

[Sythrix]

What was the total cost by the way?

About $250 after all was said and done. Of course I'm not accounting for accessory materials, like solder, wire, etc which I already had. You might be able to shave it down a little by going with slightly cheaper inputs, knobs, etc. I would expect to at least pay $200 though. Worth it for the experience!

 

[amirm]

That is pretty reasonable!

 

[Sythrix]

That is pretty reasonable!

Yeah, I feel like the quality and range is definitely more than the price you pay. Of course, not everyone wants to build an amp from scratch to save a few bucks either.

It's miles ahead of the Butte amp I had been using (if you ever read this Pete Millett, I still love my Butte amp and really enjoyed putting it together... but the truth is the truth ).

 

[Sythrix]

I visited Audio Precision at RMAF 2018 and they said they would be happy to measure my amp while I was there, so I took it in. I just let them do their thing. Some of the measurements look like what Amir usually does, but others, not so much.

He did two complete sets of measurements, one where I usually have the knob while listening, and then one set with the knob almost maxed out. The performance of the amp was much better when the knob was near maxed out.

They gave me two PDFs on a thumb drive, "Almost_Max" was with the knob set almost all the way up and "Default" was with it set close to where I normally listen.

Since the files are a little too large to upload here, I'm linking my Google Drive of them:

https://drive.google.com/drive/folders/1sNqJonh-lt4u08XeyBKOK6TBNE85VlCx?usp=sharing

A curious diversion.

 

[amirm]

Yes, as I noted in another thread, volume control position can make significant difference in performance of the amplifier. I can make such measurements but there are infinite possibilities so not sure how to make comparisons between two devices.