Bottlehead Forum

Welcome! Need support, you got it. Or share you ideas and experiences.

Return to Bottlehead Forum

Bottlehead Forum

son of demag your Telefunkens...

67.168.27.124

[ Follow Ups ] [ Post Followup ] [ Thread: Display Email Next ] [ Bottlehead Forum ]

hi all;
since i had some time on my hands while waiting for parts for the rebuild of a 1968 Fender Twin Reverb, i decided to demag a tube or two and see what the fuss is about. well, i set up my tube tester i designed and built last year that plugs directly into a mic channel of a mixer and you go from there. well, i recorded 30 sec. of noise coming out of a old 12AX7 i had lying around onto one track, and then turned off the tester and removed the tube. after a min. or so of demag. using an old Maxell tape(remember tape?) head demagnetizer i plugged it back in and repeated the process of recording 30 sec. of tube noise. RUBY TUESDAY! the demag'd track was about 6db down from the not-demag'd track and noticeably quieter. running the track faders up and down was quite the experience. well, being the skeptical sort, i tried the same procedure with a "new production" EH 12AY7 and got basically the same results! hey, tube demag'ing works; the only question now is, "...how long does this effect last?..." have fun with this one and later....
don

Follow Ups:

Re: son of demag your Telefunkens... - tianguis 18:24:19 07/28/04 (2)
Don:
I found John Swenson's original post about this. I said, "what the heck". I've done Teles, Mullards, 300B's, 6SN7's, EL34's, 12AU7's,12AX7's, 6SL7's, and a variety of rectifiers (hey, I've got 18 tubes in my analog path, 14 digital). Frankly, the first trial on my phono pre inspired me to continue. The results have been nothing short of revelatory. I don't care what the sceptics say. I have no idea how long the effect (?) lasts, but most of my tubes are 40-50 years old and who knows how they've led their lives?
Regards,
Larry Welsh
- Re: son of demag your Telefunkens... - geoduck 18:55:03 07/28/04 (1)
  Larry;
  after posting i came across an article, "Audio Hum Check List" from the May, 1953 issue of "Audio" which, under the heading of "Hum in amplifier proper" recommends demagnetizing(#17) vacuum tubes! man, after hearing the difference between the two tracks and seeing the difference in the meter levels-i'm converted...
  don
  maker America safer one guitar amp at a time...
  - Re: More son of demag your Telefunkens... - tianguis 19:11:12 07/28/04 (0)
    Don:
    I don't doubt it for a second. There are very few "tweaks" which haven't been done before, including those which are not in favor at the moment. I've seen posts poo-pooing degaussing tubes for years and must admit that I had a bias against it. No more.
    Having so many tubed components and wires and stuff jammed into my small space, I've always had a small amount of non-distracting hum. Now, there's way less hum, but there's also a large increase in clarity and micro detail. BTW, I've been using a hair dryer (cheap, exposed,noisy motor) rather than a tape-head demag or bulk eraser. I bet it puts out a stronger field, though I have no way to measure it.
    Regards,
    Larry Welsh

This post is made possible by the generous support of people like you and our sponsors:

You can not post to an archived thread.