I hear you. However, I suggest you reconsider... the difference, depending how many of the vital caps are "flipped," can be very, very noticeable. After I started doing this, I volunteered to change caps for a few friends and not one of them was not beyond pleased with the results. At a minimum, do V1B, V2a and V2B. The tone caps, arguably, have less of an effect and the lower impedance side will depend on your tone settings in this case. The cap across the bass pot I found to be irrelevant, as was the V1B NFBL cap etc.
Cheers,
Gil
norburybrook wrote:Thanks. Much as I love you guys, I'm not taking them out. it's a PIA as there's always the possibility something might fall through when trying to remove those caps and then end up having to remove the whole board.
Next time or if I get really bored one day and I don't have a million other jobs that need doing around the house
I had to search for it again a few weeks ago when I got a batch of caps in the mail. I usually do them all at once and mark them with the poor man's method.
I built an TW express and oriented caps according to supplied markings. I have since decided to do a 2nd Gen DUmble build and decided to check for outer foil orientation, only to find, the supplied markings (black line), were NOT always correct!!
I have therefore decided to check all caps on my Express buid (a real PITA!!!). I will report back on my findings if you guys are interested.
The photo from the fifth post in the thread is on a stupid file-hosting site that required me to turn off my ad-blocker to look at it. So I'm attaching a copy here.
You do not have the required permissions to view the files attached to this post.
sonicmojo wrote: ↑Wed Aug 26, 2015 5:24 am
I think this is a good thread to sticky!
I had to search for it again a few weeks ago when I got a batch of caps in the mail. I usually do them all at once and mark them with the poor man's method.
martin manning wrote: ↑Tue Aug 25, 2015 12:02 am
You'll have to remove them, but an alternate way to find the outer foil is to connect them across the input of an amp. One orientation will produce more hum, and in that case the outer foil lead is connected to the tip terminal of the amp's input jack. This is most easily done by wiring up a DPDT switch with short clip leads so you can reverse the "polarity" of the cap quickly.
I found a positive and easy way to make the amp a testing instrument.
Put a large choke over the first stage cathode. The choke is screwed to a board. The board has a pair of nails a couple inches from the choke.. The choke is on long leads and oriented to least hum. A cut 1/4" cable with clips on in is clipped to the probe nails. Touch the cap leads to it, flip it. Least hum is outside to ground.
I'm a monkey.
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
I got help from my friend who is an electronics engineer with a scope, we tested every single cap for my new #002 clone.
For testing we hooked the caps up to his scope and measured the noise, holding them between our fingertips. The noise in an amplifier would probably be considerably more but that's just my uneducated guess.
We found a BIG difference between orange drop capacitor foil placement, the noise seemed to drop around 50-70 % when measured on the oscilloscope.
For the mica caps and other non orange drop caps it seemed to also have an effect, so we marked those just for kicks, there was a difference but not a substantial one, closer to 20% really, sometimes hard to tell.
Hope that helps everybody who is thinking about cap foil placement, my friend was not convinced and thought this was closer to voodoo but after explaining to him and him measuring with me on his scope we were both a bit surprised by the difference.
For a huge build like a Dumble why wouldn't everybody do this