They were part of the kit, that I ordered, which included everything but the case.
Kit: WHAMMY Headphone Amplifier – diyAudio Store
Kit: WHAMMY Headphone Amplifier – diyAudio Store
When I built my Whammy last year it had hiss. The reason was that the front metal part of the Alps potentiometer wasn't in contact with the case. I grounded the Alps to the case with a wire, and the problem disappeared.
I read that to quickly (as usual). I see now that he has grounded the pot.
I for one had the problem that i did not get enought gain. How ever. I put the pass P1.7 aside and used a emotiva UMC-1 (as i build a 5ch honey badger, i needed a surround processor) and used the zone2 as headphone output. Oh my god what that amp delivers. Holy crap. I just do not have phones that can handle it 
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So, my board came in this week, and the parts are starting to trickle in as well. I am still waiting for a few parts, but the build is coming along slowly but surely.
The board is an old version, without a provision for the 2.2K output resistors. I decided to cut the traces on the underside of the PCB and install the resistors there, nicely out of sight. That will save me from fiddling with the cables later.
Speaking of cables: I intend to utilize some cat 6 pure copper s-ftp cables for input an output, to minimize crosstalk. Are there any downsides to using that?
The board is an old version, without a provision for the 2.2K output resistors. I decided to cut the traces on the underside of the PCB and install the resistors there, nicely out of sight. That will save me from fiddling with the cables later.
Speaking of cables: I intend to utilize some cat 6 pure copper s-ftp cables for input an output, to minimize crosstalk. Are there any downsides to using that?
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I recommend you stick with the LED method for now and make that work. It really is the simplest method. I've built 3 and tried the various options, and I'd strongly say to stick with that.
Did you check the polarity of the LED? I bet you have it in backwards. I did that on my first build. LEDs have an anode and a cathode so make sure they're in the right way. You can easily test this on your DVM by putting it into diode mode. When its on the right polarity, the DVM will make it light up. If you don't have a DVM as a last resort, check the data sheet for the LED. Also note that depending on the LED you used, you might have blown it by putting it in backwards. The diode test on the DVM will clearly indicate that. The diodes used in the kit are pretty cheap. If you really need one, goto mouser or digikey and get yourself 100 of them for ~$15 so you never are stuck without replacements.
--Tom
Is it ok to use 100uf caps at C8, C9, C10 and C28? There is an addendum in the BOM in the start post that says 100uf is ok for the 220uf caps in the BOM, but it can also be interpreted to read that it's only ok for the op-amp caps C3 and C4. I have some nice Nichicon KZ 100uf that I would like to use if possible.
You'll be fine Swifty, I've used 100 - 1000uf for C9/C28 before and no discernible difference. I believe Wayne had lots of 220uF in stock so used them everywhere!
It is hard to see but on your first photo you have a black wire connected to the ground/return. Where does that come from?
Does the hiss come/go when you touch the volume pot's case/knob or other parts of the chassis? One thing I've had to do with these anodized chassis is sand off the coating anywhere the chassis components touch so that we have solid continuity. You can simulate this by connecting the panels/etc... using alligator clips or probing around with your DVM too.
--Tom
Yes, that anodizing film can be quite a good insulator indeed
I countersink the metal surfaces for the bolts and also scrape the top surface and use the 'star-washers' - I've made up a 'kit' of the star washers, cup washers, flat washers, and those nuts with the serrated locking edges - saved searching around for the parts each time.
It's good to be thorough with this and generally, doesn't need to be redone - a good and simple practice!
I countersink the metal surfaces for the bolts and also scrape the top surface and use the 'star-washers' - I've made up a 'kit' of the star washers, cup washers, flat washers, and those nuts with the serrated locking edges - saved searching around for the parts each time.
It's good to be thorough with this and generally, doesn't need to be redone - a good and simple practice!
If you remove the chassis anodizing, star washers are typically zinc plated steel in contact with raw aluminum. I use a thin film of DeoxIT D100L to prevent oxidization of the aluminum that might cause a resultant increase in contact resistance.
Many years ago, this product was sold as Cramolyn Red:
https://www.amazon.com/dp/B0002BBVN2/ref=emc_b_5_t
Many years ago, this product was sold as Cramolyn Red:
https://www.amazon.com/dp/B0002BBVN2/ref=emc_b_5_t
Hey guys,
thanks a lot for your kind answers and suggestions.
The black wire is for grounding the pot, which reduced a hum I was getting by a lot. The noise changed when wouching the pot and that issue is now gone.
However I am still hearing a hiss, which is not altered when increasing the volume (contrary to ground induced humming noises). I am using Meze Audio 99 Classics and with those headphones I can even hear the noise floor while listening to music.
With a loaner Focal Elear the noise is completely gone! Could it be, that my Meze pick up the amps noise floor due to their low impedance or lower sensitivity of some sorts? If so, is there any way to further reduce the noise (hiss), so I can use my Meze with the Whammy?
thanks a lot for your kind answers and suggestions.
The black wire is for grounding the pot, which reduced a hum I was getting by a lot. The noise changed when wouching the pot and that issue is now gone.
However I am still hearing a hiss, which is not altered when increasing the volume (contrary to ground induced humming noises). I am using Meze Audio 99 Classics and with those headphones I can even hear the noise floor while listening to music.
With a loaner Focal Elear the noise is completely gone! Could it be, that my Meze pick up the amps noise floor due to their low impedance or lower sensitivity of some sorts? If so, is there any way to further reduce the noise (hiss), so I can use my Meze with the Whammy?
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The change in hiss/etc... is a sure sign you still do not have solid continuity between the POT's base and the rest of the chassis, including the chassis itself. You should have it to the point where touching the chassis anywhere including the POT doesn't change the current return path. It took me a good time to figure this out on my first Whammy but it is worth it; it should be completely silent.
--Tom
Do you have a earth/gnd lift or is the chassis connected to AC gnd (where your power inlet is)? You should tie the pot to chassis, not to audio gnd. Ideally, your chassis is tied to earth but not to audio gnd. Audio gnd should only be connected through a ground lift or ground loop breaker of some sort. In 6L6's build guide, he is using the film capacitor at the input to do this.
Looking at your picture - put an eyelet on the pot grounding wire and tie it to the board mounting bolt instead of audio input ground.
Looking at your picture - put an eyelet on the pot grounding wire and tie it to the board mounting bolt instead of audio input ground.
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Ok, thanks a lot! I will try grounding the pot to the chassis and sand the anodizing from the parts of the chassis, that are in contact to each other.
While playing around with temporary wires from each chassis part to the ground, I noticed something: everytime i would turn the amp off the music keeps playing for a few seconds. Right in that moment the noise floor is completely gone, even with the sensitive Meze Audios. Could there be an issue with my power supply and how can I test it? Homework for me: sanding the chassis and proper grounding of the poti.
While playing around with temporary wires from each chassis part to the ground, I noticed something: everytime i would turn the amp off the music keeps playing for a few seconds. Right in that moment the noise floor is completely gone, even with the sensitive Meze Audios. Could there be an issue with my power supply and how can I test it? Homework for me: sanding the chassis and proper grounding of the poti.
The standard gain and 10k ALPs pot seems to work great with my 300 ohm HD650's.