Cliff Schecht wrote:I just finished up a 5F6A build recently and have been using it a lot at band practice. It's one of the quietest amps I've built, even dimed. I used the stock 0.1uF coupling caps so it does fart out when distorting the power amp but I run it clean with a 12AY7 in V1 anyways. With that said, I do get a hiss with the occasional light popping like what you describe. It's nowhere near enough to be bothersome, in a room that's anything other than dead silent you have to put your ear up to the speaker to hear it, but it's there.
To be honest, most of my old Fender builds do this. My Express does it, my Rocket does it when dimed. Maybe I've just gotten used to this sound. Once you kill all of the hum in a high gain tube circuit there is still an appreciably high noise floor usually. This is sort of the nature of the beast, we are relying on electrons blasting around in a vacuum sealed glass envelope at light speeds. Sometimes electrons bump into other electrons and make it to the plate when they aren't supposed to. I haven't studied the exact mechanism in depth enough to give a fully informed answer but like I said, it's to be expected when using such an archaic way of amplifying a signal.
In an amp like the 5F6A that has quite a bit of gain on tap, more than needed to reproduce a clean output wave, and so the noise floor in the first stage becomes especially critical. I usually will roll a few tubes to find the lowest noise one in a higher gain amp. In an amp like the tweed Bassman the choice is easy, a 5-star GE 6072A (black plate) is about as good as it gets noise-wise IME with this circuit.
The noise has been reduced enough that I may just quit worrying about it unless something happens. I don't gig. I'm just a home player (but I can play LOUD), so the noise was bothering me somewhat.
I'm using a NOS JAN GE 12AY7 in V1. It was what my budget allowed.
statorvane wrote:Okay, I remember something else. I had a situation a few years ago where I was getting some weird effects that I thought were in the amplifier, and eventually found the culprit was my new, $25 Hosa cable. A real piece of junk - it was microphonic! Have you tried a different cable?
I'll never buy Hosa products again. Pure junk.
Also, I'm not sure what jacks are included in the Weber kits, but I recall when I was building my clone there was a good bit of grumbling about the jacks that were included with the kit. Virtually every forum post suggested upgrading to Switchcraft jacks. I isolated the jacks from the chassis. If you've wired it up, and you have a wire from switch ground to a grounding point, you may want to try isolating yours too. I used black electrical tape around the chassis where the inputs jacks are.
I use Planet Waves cables. The ones that are twisted/shielded pairs. I tried different cables while troubleshooting but it made no difference.
My input jacks are wired exactly as you describe, each with a separate wire to the brass gounding plate. I considered isolating them and even have the proper washers to do so. Unfortunately, to do so now would require completely disassembling the amp (something I am loathe to do) in order to enlarge the holes in the front panel.
johnnyreece wrote:Weber says they're shipping with Neutrik jacks now. Doesn't guarantee quality, but it gives a much better shot than what they used to have.
Correct. I have even had Switchcraft jacks fail. I use the Mil-Spec Switchcraft jacks in all my guitar builds. Never had a problem with those.
johnnyreece wrote:Weber says they're shipping with Neutrik jacks now. Doesn't guarantee quality, but it gives a much better shot than what they used to have.
The Neutrik jacks that Weber provides are fine quality, no need to improve. I've built a 5F6A, a 5E8A, and a Tore-Vibe from Weber kits, and I haven't had any problems with noise or the jacks. I've also ordered plenty of extra Neutrik jacks for other builds.
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