Gibsonman63 wrote:Also, wiring the heaters on your power tubes correctly helps cancel hum, but there are tons of vintage amps out there where they crossed them, especially old Fenders. I usually lay one of my heater wires flat on my bench and run a stripe across it with a sharpie so I can easily tell them apart. Some people use different color wires for the same reason.
+1 I actually wired them that way before knowing this, but then read Webers "the ultimate guide to tube amps" book where he explains this.
I'm now up to wiring up the heaters using the "lazy loops" etc.
Per the build guide I was wiring red wire from Pin 2 on V5 to pin 2 on V4 to Pin 4&5 on V3, 4&5 on V2, 4&5 on V1.
Black wire is Pin 7 on V5 to Pin 7 on V4, to Pin 9 on V3, PIN 9 on V2, Pin 9 on V1
I'm not sure why, but my loops got bigger as I went.
I just wanted to check with you all that I have it correct and everything looks good before I solder the wires. Does this look correct? Anything I should adjust?
I am new to this lazy loop thing so I might not be the best help/advice.
But if you want to make it look a little more uniform, you could maybe just cut 1'' off the black and red at V1.
I have built only 2 amps so far 1st was a D-style OTS FM50 and 2nd was a 2550 Marshall clone both from ceriatone kits. On both I stuck heater wires in a drill chuck and twisted tight as a frogs ass. That seems to be the recommended method for those amps but I am just starting an Express build so this topic does interest me as I do know Ken F. knows his shit.
I have heard many times that these amps are noisy and hard to tame so I would instinctively run my heaters twisted tight so when I fire her up it wont be of concern, unless any seasoned TW builders can chime in as to why lazy loop is preferred.
Below is my 2550 build which I took pics of from start to finish if you want to see how I ran my heaters. No noise issues on that build whatsoever.
I have not read through the whole thread yet but can I ask is there any issue with doing a tight loop as opposed to the lazy loop?
I dont mean to hijack here but personally an not trying to do an exact clone but am interested in what the benefits would be by doing the lazy loop. Unless heater/ac hum is part of the tone, I do not see any.
I do ask with all due respect, see I just dont know
There have been numerous threads on this subject and no consensus. I have seen heaters done in bar wire, straight line, loose loops, tight loops, raised above the sockets and against the edge of the chassis. In each instance there are examples of success with these varying methods. Proof will be in the pudding, does it hum?
Thanks man
I see its just a matter of what works.
Whether its heater hum or lead dress one thing i strive for is as much distance between wiring as possible, but have not put much thought into the twisting of the wiring.
I think the idea is to have equal distance between the wires to cancel hum, so that's why bus bar heaters work, tightly twisted wires, or a lazy loop. The lazy loop seems to work really well and approaching the tubes can be a little easier. I think it might actually help lead dress be a tiny bit easier as a whole
I think I may have a problem. Following the build guide, I was going to use 18 gauge stranded trannie clippings for the two sections suggested in the guide. I used trannie clippings from the yellow wires that go to the diode stack and connected it from the bottom of the 25k cement resistor to PIN 6 of V5
Unfortunately, I did not look closely enough at the clipping and only after it was in place did I notice that even though the wire was physically thicker than the 20 gauge, it was actually a 22 gauge wire that I was using. Uh oh... it will be difficult to desolder the 22 gauge and put in a 18gauge clipping instead.
However, I did notice that the wire shows 22awg and also says 600v. The reason for using the 18 gauge wire according to the guide was that the voltage was too high for the standard 20 awg 300 volt wire.
Does the 600 V showing on the clipping mean I might be okay using this clipping? Or should I swap it out?
Unsoldering is never fun, but that wire carries a lot of juice to the output tubes, like 400 volts. The smaller guage wire will probably work OK but I would do the right thing and remove it and put something bigger there. You also might want to rethink running wires under the choke resistor as it gets very hot and can melt insulation. I drilled a hole in my board and came in from the bottom. My express is one of the newer posts about hiss if you want to see a pic of the lead dress
amplifiednation wrote:Unsoldering is never fun, but that wire carries a lot of juice to the output tubes, like 400 volts. The smaller guage wire will probably work OK but I would do the right thing and remove it and put something bigger there.
This is where one needs to sort out the difference between voltage and current vs insulation and wire gauge.
Insulation value corresponds to voltage - if a wire carries high voltage, the insulation value is what matters. If a wire is carrying high current, then a larger diameter wire is appropriate.
amplifiednation wrote:Unsoldering is never fun, but that wire carries a lot of juice to the output tubes, like 400 volts. The smaller guage wire will probably work OK but I would do the right thing and remove it and put something bigger there.
This is where one needs to sort out the difference between voltage and current vs insulation and wire gauge.
Insulation value corresponds to voltage - if a wire carries high voltage, the insulation value is what matters. If a wire is carrying high current, then a larger diameter wire is appropriate.
So in this case, am I carrying a high current? Or just a high voltage? If it is just the voltage, then I can leave the wire as is. If I need to allow for more current I will need to replace.
amplifiednation wrote:Unsoldering is never fun, but that wire carries a lot of juice to the output tubes, like 400 volts. The smaller guage wire will probably work OK but I would do the right thing and remove it and put something bigger there.
This is where one needs to sort out the difference between voltage and current vs insulation and wire gauge.
Insulation value corresponds to voltage - if a wire carries high voltage, the insulation value is what matters. If a wire is carrying high current, then a larger diameter wire is appropriate.
So in this case, am I carrying a high current? Or just a high voltage? If it is just the voltage, then I can leave the wire as is. If I need to allow for more current I will need to replace.
