I ran a wire from the input ground terminal bus to chassis ground and the hum is gone.
First I ran a wire from the ALPS pot body to input ground but using a chassis ground is easier.
Input RCA inputs are isolated , ground tied together and to the Whammy Ground adjacent to the input left and right
Hmmmmmmm.... That's really interesting. (The recording is cool, what did you use to make it?)
Let's start where we always start, please post well-lit, in-focus photos of your build.
I'm carefully testing prior to using a chassis. So, don't judge my lack of tidiness too much, yet!
I have a .1UF WIMA between earth from my IEC and the ground of the RCA inputs, which is connected to that ground bus above the input PADs. Is this correct?
Good point. I thought about the OpAmp as being a problem. I have one of those sockets to allow for OpAmp "rolling". Are these notorious for having contact issues?
Only if you try to use round pins in leaf spring sockets. Other than that, they can add 'negligible' capacitance which would alter the performance, but it is minuscule.
You've created three more DIY / WHAMMY addicts
I had a few people listen to my WHAMMY, and they wanted one. I smugly said... Well, you can build one.
Three folks came over on Saturday for the builds. Thanks to the DIYAudio team for getting the 3rd out for a last minute addition so quickly. Arrived JIT.
Three very happy campers. It took them a full day with breaks. I'm sure someone can do it in the 2-3 hours suggested, but not me
Thanks again!
I had a few people listen to my WHAMMY, and they wanted one. I smugly said... Well, you can build one.
Three folks came over on Saturday for the builds. Thanks to the DIYAudio team for getting the 3rd out for a last minute addition so quickly. Arrived JIT.
Three very happy campers. It took them a full day with breaks. I'm sure someone can do it in the 2-3 hours suggested, but not me
Thanks again!
My first post at diyaudio. Thanks to Wayne for the design and to 6L6 for the detailed guide. I got the transformer from Antek and the enclosure from Aliexpress. I used the recommended parts except for C13, C23 (Audyn instead of WIMA), C12, C17, C22, C25 (Audio Note Kaisei instead of Nichicon MUSE bipolar), and C1, C5 (ClarityCap). The power filtering caps are also different but I don't think they will have as much influence on the sound. I found that replacing the WIMA significantly improves the sound. This is consistent with my past experience--most of the time WIMA film caps seem to introduce some hardness to the overall sound signature and make it less lively. The Audio Note caps are a little overkill but they also improve the sound by a large margin compared to the Nichicon bipolar caps, although these are polar. I have built another WHAMMY using Nichicon KZ caps for these positions, and found they also sound better than the bipolar ones. By building this I also learned that having large bias currents does not always lead to good sound. Initially I set R16, R22, R29, R32 to 5 Ohm, making the bias current 120 mA, but the sound was just terrible. I was very disappointed and accidentally tried switching them back to 10 Ohm (60 mA current). The difference was night and day--the sound is very warm and soothing, but with enough punch and speed. For the opamp, I tried a number of different ones and finally chose OP249 by Analog Devices. I found that it has a good balance between warmth and accuracy. BTW I have been using WHAMMY with Sennheiser HD650 and Massdrop HD58X. The WHAMMY easily outperforms all my other headphone amps.
Attachments
cap
Try the Panasonic EEU-FC1V332. Currently in stock at Mouser. 3300uF, 35V, 7.5 lead spacing
Try the Panasonic EEU-FC1V332. Currently in stock at Mouser. 3300uF, 35V, 7.5 lead spacing
Peculiar problems have arisen with my Whammy built a couple of years ago.
The right channel of the amp gives only ~2 V rms before clipping into a 70 ohm load. The left channel goes up to ~7,2 Vrms. This happens with many types of opamps.
Everything else seems to be ok and for example gain is 3x on both channels and also sine waves are ok up to at least 40 kHz. Bias currents measure about 58mA and are steady.
The problem may well have been there from the very beginning. This was the first time I tested it with scope. I haven’t heard any audible problems though.
Any thoughts what might be wrong in my build?
The right channel of the amp gives only ~2 V rms before clipping into a 70 ohm load. The left channel goes up to ~7,2 Vrms. This happens with many types of opamps.
Everything else seems to be ok and for example gain is 3x on both channels and also sine waves are ok up to at least 40 kHz. Bias currents measure about 58mA and are steady.
The problem may well have been there from the very beginning. This was the first time I tested it with scope. I haven’t heard any audible problems though.
Any thoughts what might be wrong in my build?
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