Hey guys, I recently swapped the caps (in the audio path) of my WHAMMY and now I have noise in the right channel. It's intermittent and I can only hear it on my more sensitive cans (Focal Elegia) but when it's there it's pretty loud. I reflowed all the connections but it made no difference. Also, I don't know if this was there previously as I was using a different op-amp that doesn't exhibit this noise (OPA2107). I'm now using the AD823 which I prefer. Any help in tracking down the issue would be appreciated. The noise is a "shhhhhhhhh".
Minimize the variables. Go back to the original caps and try the different OpAmps. Check the data sheet too and ensure that the pinouts are compatible, as well as the parameters for caps/resistance around the opamp. For example, some of the higher-end OpAmps become unstable if you use low-ESR caps around them because they expect a certain amount of resistance, etc.... Some need certain value bypasses around them, etc...
Remember that OpAmps can be pretty complicated circuits that all have certain design assumptions and requirements that are listed in the data sheets/application notes, and as such are not %100 swap-compatible.
--Tom
My immediate suggestion would be to give your solder job an extra touch with an iron.
Yeah I did that already with no change 🙁 .
Thanks everyone for the suggestions. Will take a look at the ESR of the caps (Audio Note) and perhaps swap the originals back in to see what happens.
Your caps, they're not by any chance som huge audiofile caps that is not even close to fit the fottprint on the PCB?
EIDT: i see now that it is Audionote. so answer: yes. The legs of those caps is som realy good antennas. Try the old caps.
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Interesting! Will go back and shorten them and see what happens.
BTW, I noticed after shut-off, D5 stays lit for several minutes while D6 goes off almost immediately. Does this imply an issue with one of the regulators?
Attached is a pic of the caps (they're the 8 gold colored ones). Next to the opamp and XLR plug they're bent so as to be out of the way.
Attachments
Got all my parts in and started working on things and realized I have no hardware for the heatsinks. I never saw anything about hardware in all the threads or the BOM and can't find any in my searching. Was it expected that they would come with something? Can I just rig it up with anything or should I try to get the right size stuff and the little star nuts? I liked the ones I saw in the diy pics (https://d17kynu4zpq5hy.cloudfront.net/igi/diyaudio/YxErqHc6nJlZbiZb.medium). Anyone have the details on those? Thanks!
I put in these: Access to this page has been denied.
(Link is mouser.com/ProductDetail/530-5TT500-R)
I am pretty sure I found them mentioned in a post somewhere in this monster thread while I was searching for IEC information.
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For the primary side, I divide the max VA of the transformer by the net voltage, and multiply that result by 1.5 to get to the fuse value.
So, assuming you're in a 120V region of the world, and assuming the standard 25VA transformer:
25/120=0.208
0.208*1.5 would mean a 0.315A fuse
A 0.25A fuse would probably work fine as well, maybe depending on how stable your local power grid is. A 0.5A fuse would obviously work, but so would a nail 🙂
I live in a 240V part of the world, and I use a 0.16A fuse.
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In case you were contemplating running the mosfets without heatsinks - do not, or you can fry them up pretty quickly.
You need heat sinks that will work for TO-220 - same as those for the voltage regulators (so you need 6 of the same). They come in different lengths, but I think this is the one that comes with the Whammy kits from the store as I have a bunch on-hand.
https://www.mouser.com/ProductDetai...HtE11pWevfpyt/Mox9RWUjgOs/U225zUyyCuWlN4yuw==
I've used the above and a variant that is the longer/taller variety too. Get the tallest that fit your case as more heat dissipation will not hurt in this build. Of course make sure of the mounting peg spacing and area of the fins so that it fits the mounting holes on the board and the space provided.
--Tom
Thanks for the reply Tom. I got some good information from many of your posts in this thread while doing my research.
I ordered 12 of these (mouser # 532-531102B25G) for my 2 builds I am doing: Access to this page has been denied.
I need to buy the hardware to keep the surfaces tight. I have some random nuts and bolts that are kind of working for the moment so I could get the soldering height correct but I don't have enough and the bolts are too long and are slotted (ugh). I would prefer to order the right size stuff, like the phillips-head ones in the picture with the star nut or clip on ones I have seen, if that is better.
The Talema data sheet for the 25 watt transformer calls out 160 mA @ 230 V which would be 320 mA @115 V. Closest stock value would be a 315 mA. A typical 5X20 mm Time Delay / Slow Blow from Mouser would be:
https://www.mouser.com/ProductDetail/Bel-Fuse/5ST-315-R?qs=MvPYbBWWJyvttGAebJE%2BXA==
smd version
For the fun of it, I produced a SMD version of Whammy.
My objectives:
I have many spare parts;
I want to try different mosfets;
I have bunch of opamps for testing;
I want to try the Rubbycon’s PMLCAP. It claims to be an excellent choice for coupling and decoupling.
There is no Power supply section so I am free to go with other PS+regulators.
It is a good Kicad exercise.
1. I tested it with IRF530/9530 and sounds alright;
then I went with MTN12N10/MTN12P10 by Motorola.
Motorola FETs particularly renders the mids and highs beautifully.
2. Conductive plastic Pot is my favourite so I finally picked TKD 601 @10KA.
3. My final choice for regulator is Salas’ Ultra BiB.
It certainly is hot but sound better compared to my opamp based regulator or LT3045 regulator.
(LT3045 type regs sound awkard-less bass and less treble and extremely detailed but mids).
4. For the PMLCAP, they are 1uF/16V for the input coupling caps.
They work fine and they sure look pretty with the holographic color shift!
I can post the Gerber file here if anyone is interested in this. Hope it does not create any conflict of interest against the diyaudio store.
For the fun of it, I produced a SMD version of Whammy.
My objectives:
I have many spare parts;
I want to try different mosfets;
I have bunch of opamps for testing;
I want to try the Rubbycon’s PMLCAP. It claims to be an excellent choice for coupling and decoupling.
There is no Power supply section so I am free to go with other PS+regulators.
It is a good Kicad exercise.
1. I tested it with IRF530/9530 and sounds alright;
then I went with MTN12N10/MTN12P10 by Motorola.
Motorola FETs particularly renders the mids and highs beautifully.
2. Conductive plastic Pot is my favourite so I finally picked TKD 601 @10KA.
3. My final choice for regulator is Salas’ Ultra BiB.
It certainly is hot but sound better compared to my opamp based regulator or LT3045 regulator.
(LT3045 type regs sound awkard-less bass and less treble and extremely detailed but mids).
4. For the PMLCAP, they are 1uF/16V for the input coupling caps.
They work fine and they sure look pretty with the holographic color shift!
I can post the Gerber file here if anyone is interested in this. Hope it does not create any conflict of interest against the diyaudio store.
Attachments
That is VERY cool. Congratulations and thanks for sharing. This type of thing inspires me to continue to learn.
Quick question: on shut down, one of the LEDs goes off almost immediately. The other stays on for a couple of minutes. Is this normal?
Did you happen tap into the positive or negative power supply bank to add an external LED?