Well, kiss my capacitors! This is so right, ground causes more problems when it is not well done. This solution reinstates Leo's genius ground. The buss system is only as good as the solder tech and many of those who solder are not the paragon of technicians, witness the 'pull off' connection. When I used to play for money, I got knocked on my a$$ so many times, holding an electric guitar and putting my lips on a vocal mic, I hired a guy to put ground lugs on the back of every chassis. I then used a spool of bare copper to go from lug to lug to lug, then to a water pipe or even sometimes a ground rod outside the stage door. That stopped the shocking and lip splitting, made the whole stage rig quieter. Great Job D-Lab, superior! (as always!)
Hi D Lab What is your method for wiring tube sockets and pots and jacks. I know people discuss mechanical connection but others just go straight into the eyelet, with serviceability in mind. What do you recommend? As far as serviceability?@@d-labelectronics
Thanks for the deeper dive on this subject. I just recently viewed your previous video that detailed the process of creating and installing the brass shield / ground plane. Perhaps you could provide a link to it in this video's description for other viewers to reference. Cheers!
In higher gain amplifiers I think of the buss wire on the backs of pots as a way to ground the covers of the pots ONLY in order to prevent the pots from picking up noise from inside the amplifier. This is for the same reasons that you point out in this video - the poor "ground" connections to the chassis. I usually run this wire with no other circuit ground connections made to it. Note that you MUST ground the covers ONLY to the appropriate circuit grounds to see this benefit(so it is not a continuous ground buss across all pots). For what it is worth I havent seen problems in vintage fenders as far as grounding goes, so the brass groundplane is a good way to make it far easier to ground all those connections (For soldering, because most folks dont have a 200W soldering iron).
I did this when I made my mojotone tweed pro. I was listening to a podcast where they asked Fender why they did that, and their answer was simply that it was easier to solder to the sheet stock than put a wire across all the pots. No electrical or scientific advantage, and it wouldn't matter either way - as long as it's done right, but the sheet stock way was just easier. As a hobbyist builder, I just make sure I get 0's on my voltmeter from all points.
D LAB, Also you should do a video lesson on separating the preamp grounding scheme with the power amp grounding scheme to increase the Signal to Noise Ratio. A lot of repair techs are not isolating the preamp grounds from the power amp grounds because of various hissing, noises, buzzing, etc. I'm not sure at what point they break the circuit up, maybe BEFORE the phase inverter section or AFTER the phase inverter section they will isolate the grounds from the preamp to the power amp.
Hello Terry, Great video. The only thing that comes to mind is the issue of rattle. The ground plane appears to be be a good solder point and the properties in the brass are almost universally compatible with any metal types so A+ on that notion. However the plate sounds a little loose in the can and may cause other noises at certain frequencies as the speaker oscillates through its tones. Im having this issue with a Marshall combo 1x12 jcm900 amp and the plastic grab handles can get so loose that it actually sounds like a blown speaker. I have tamed it down using some O-rings but it still has some buzzing at the plate to box connection and i will likely have to replace them with all metal handles. it might be necessary to put a few nuts and bolts or rivets along the bottom of the plate. Just a thought.
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I have this kit coming tomorrow, and shim stock also on the way. In addition to drilling the front panel holes, I plan to drill a small number of small holes (~1/8") on the back edge (closest to the eyelet board) for the ground wires to put through before soldering. Good idea? Or no....warn me off if "no". Thanks for all these videos on this issue!!! :-)
I've done both ways.... with good success. However, I usually prefer the brass plate... BUT getting the plate to take solder is a bit tricky for rookies... gotta have a super iron.
I build that same amp and used the bus grounding scheme. Seemed to worked okay for a while. But the amp has developed a strange rush noise that comes and goes. Kind of sounds like one of those sparkly, crackling 4th of july fireworks when it really gets going. If I change the V2 preamp tube it goes away for a while. But eventually, it rears its ugly head again. I was thinking I made a crappy soldier connection somewhere (maybe a ground), but perhaps the brass plate will solve my problem. Think I'm going to give it try.
If anyone is interested, I did away with the buss grounding scheme. I followed D-labs advice and installed a .010 piece of brass shim stock. Well, long story short... it worked!! Pesky noise issues are gone!
Amps like guitar amps are usually made to be mobile. Just moving it around may dislocated a wire to a pot eventually. That posibilty alone should be taken into account ( besides what Terry has mentioned in the description) in using the Fender brass plate ground plane design especially if you are doing this to someone elses amp. So yes ,Terry is correct on all counts.
@@d-labelectronics Terry, do you remove the star washers from the pots' before installing? Brass on brass makes sense I guess, right? PS. I'm just happening to be rebuilding a 95' Twin and I'm doing the same procedure. Thx!
I've wondered why Marshall and other higher-gain amps don't bother with using a similar brass plate (or at least something other than just wiring the backs of all the pots with a buss wire)? Is there something in their design that keeps the electrical interference at bay that the Fender doesn't, or was Marshall just ignoring/oblivious to it?
It "could" work; but I wouldn't do it. The foil is great for shielding from outside RF interference. But as a conductor meant to complete the AC and DC circuits (circular paths) it will like be insufficient. One could argue that since the traces on a PCB or just little strips of foil, and they do just fine, what's the problem? Maybe nothing. But if you're into your amp elbows-deep, might as well do things in a way that offer the best of what you can do rather than what we can simply get away with. For my amps (and I mean MY, as in, I build them for myself), I always strive for, as close as I can, to a proper 'star' configuration. Since I only build SE and PSE, actual point-to-point, it's easier for me to map out the layout that lets me get my grounding paths and connections to get rid unwanted interactions and interference quite well.
With thin brass stock, you can actually use regular scissors, even the kind with plastic handles and get a pretty nice cut. Works better than tin snips on thin stock. It will dull the scissors for paper or cloth cutting so get a pair just for metal.
