Carl that is nice work. You've thought it out well. Would you offer a Gerber file or similar of that?
Assuming that you are thinking of the JFET DOAs ...
I sell them on EBay under the 'KAD Products' name as the MOX JFET as well as on Etsey - KADProducts on Etsy
I actually make and sell several DOAs. I just don't bother to promote them. Perhaps I should.
I am using the burson v6 vivid with full Led configuration since 1 month without issue. My case got a quite good airflow, and the v6 still gets very warm on the touch. So i would recommend to go for 15v only if your case is completely closed, or if you do not need the extra voltage swing.
Polarity question. I borrowed a friend's iFi iDSD Micro (one silver, one black) to test. I have a switch box for my headphones, so I can feed the same signal to multiple DACs from my Mac (Audio MIDI program does this), and have multiple amps output to my switch box, then to the cans. I just need to change the switch on the box to switch between the amps. I'm comparing three dacs and amps with a very easy way to a/b/c/ switch them.
When I listened to some warble test tones, I noticed a significant difference between the iFi units and the WHAMMY. The iFI has a polarity switch, and when set to +, it sounds just like the WHAMMY. When set to -, there is a noticeable difference.
So, now my question: Do I need to care about polarity?
OK, another question: under what circumstances would I want to switch the polarity to -?
Assuming switching polarity is desired, where in the path is it switched? Input? Output? in between?
Thanks,
Allan
When I listened to some warble test tones, I noticed a significant difference between the iFi units and the WHAMMY. The iFI has a polarity switch, and when set to +, it sounds just like the WHAMMY. When set to -, there is a noticeable difference.
So, now my question: Do I need to care about polarity?
OK, another question: under what circumstances would I want to switch the polarity to -?
Assuming switching polarity is desired, where in the path is it switched? Input? Output? in between?
Thanks,
Allan
rotate your head for 180deg ?
not easy on SE input amp ...... in case of balanced input - easy - just replace connection of pos and neg input
also - on output/headphones side - you can't do that with majority of cans , too - most of them having L+R+GND in one cable , all the way to one can
however , most likely not worth the fuss , except in case that you're seeeeeerious can user
edit: if you choose to go with balanced feed/cable route , it's easypeasy - wherever convenient - on amp itself or in intermediate box (between amp and cans) just put 2 sets of output jacks , one wired normal, second with flipped phase
not easy on SE input amp ...... in case of balanced input - easy - just replace connection of pos and neg input
also - on output/headphones side - you can't do that with majority of cans , too - most of them having L+R+GND in one cable , all the way to one can
however , most likely not worth the fuss , except in case that you're seeeeeerious can user
edit: if you choose to go with balanced feed/cable route , it's easypeasy - wherever convenient - on amp itself or in intermediate box (between amp and cans) just put 2 sets of output jacks , one wired normal, second with flipped phase
Last edited:
Allan
You would care about polarity when another component might reverse it and you can hear the difference. For instance, if you were using the iFi iDSD Micro as a DAC to feed a B1 Korg preamp (which inverts polarity), you could set the iFi to minus (invert) and that would save you from having to invert the loudspeaker leads to get things back to normal. Polarity can be corrected at any point in the signal chain. The objective is to maintain the same polarity as the original recording or source material at the final transducers.
Now, some folks say polarity is no big deal. There have been "scholarly" articles claiming that you can't hear the difference. Some manufacturers ignore the issue. I have a Cambridge Audio integrated amp that inverts polarity and there is no mention of that in the owner's manual. That one is a simple fix, I just reverse the speaker connection polarity and do not use the headphone jack.
Personally, I can hear the difference and especially on headphones. I really like that the Whammy does not invert polarity, unlike, for instance, Pete Millett's NuHybrid Headphone Amp. I even went to the trouble of adding some high quality input reversing transformers to the NuHybrid to correct that issue when I built it.
One final comment. There is an easy way to verify absolute polarity of a system, including the preamp/power amp and loudspeakers or a headphone amp and headphones. Unfortunately it would not include a DAC or other source in the test.
"Mobile Tools by Audio Control" is a free smartphone app (for iOS only) that has a polarity check "popper" that I have used. "Polarity Checker" is available for android but I have not tried it. With each, the line level out of the phone generates a 'popping' sound that the phone mic checks for absolute polarity. I have not tried it for headphones but it seems it would work if you were very careful to use the lowest possible level and place the phone mic as close as possible to the the headphone transducers.
"Mobile Tools by Audio Control" is a free smartphone app (for iOS only) that has a polarity check "popper" that I have used. "Polarity Checker" is available for android but I have not tried it. With each, the line level out of the phone generates a 'popping' sound that the phone mic checks for absolute polarity. I have not tried it for headphones but it seems it would work if you were very careful to use the lowest possible level and place the phone mic as close as possible to the the headphone transducers.
I encountered the same issue when I started building mine. I am using the Galaxy 2U w/Aluminum Covers, which are 10mm thick. I originally drilled out the faceplate to accommodate the stock and came to the same conclusion that I didn't want it contacting the chassis directly, so I went with the Neutrik recommended above. Works like a champ.
I completed the built my first WHAMMY this weekend including the chassis and I/O connectors as specified in the build guide. As far as I can tell from the forum and build guide, the test points I've checked all measure correctly. However, when I plug the amp into a source, all I get is buzzing out of the headphones. I've tested the headphones and source independently and both work fine. I've made sure everything is grounded, and that there is continuity from the negative RCAs through the isolating capacitor to earth ground. I've also confirmed continuity between the L/R + to the board, and from the board to the headphone L/R/neutral pins too.
I'd really appreciate any tips/ideas for what might be wrong.
Thank you in advance!
I'd really appreciate any tips/ideas for what might be wrong.
Thank you in advance!
Look around and check the op amp, it might be oscillating. Try another op amp.