Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: p2pAmps on August 20, 2016, 11:15:50 am
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Here is another Doug Hoffman Eyelet board Bassman for a guy in FL. AA864 in the middle and the British side on the left. Waiting for a chassis next...
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57b881c0cd0f68daca512ad9/1471709634360/Bassman-Clone.jpeg?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57b881c0be6594880d201cd9/1471709633897/2.jpeg?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57b881bfbe6594880d201cd2/1471709633422/3.jpeg?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57b881bfcd0f68daca512ad4/1471709633885/4.jpeg?format=2500w)
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Need horizontal line under the date marking. Otherwise it's ambiguous whether you mean "8/16" or "9/18".
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Any thoughts about eventually moving to only 4 diodes (or even just two) on the power supply/bias board?
I know 6 is traditional, and a couple-less diodes doesn't save much money. However, those 1kV 1N4007's are much sturdier than what Fender used in the 60's, so 6 total aren't needed anymore. And it might be a little less space...
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Starting to resemble an amp :)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57bb9fae9f7456ac242ff99c/1471913907565/1.JPG?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57bb9fae2e69cf3c7948a53c/1471913906278/2.JPG?format=2500w)
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(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57c09a909f74561536b32f8e/1472240274226/IMG_7027.JPG?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57c09a8fcd0f681633bc847f/1472240274403/IMG_7028.JPG?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57c09a8f9f74561536b32f8b/1472240272570/IMG_7029.JPG?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57c09a8e9f74561536b32f87/1472240272501/IMG_7030.JPG?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57c09a8d9f74561536b32f82/1472240271726/IMG_7031.JPG?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57c09a8c9f74561536b32f7c/1472240270810/IMG_7033.JPG?format=2500w)
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57c09a8ccd0f681633bc8474/1472240272555/IMG_7032.JPG?format=2500w)
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I have a question about your front panel brass plate. Does it have a dedicated wire soldered to it that bolts to the chassis? Or, are you relying on the mechanical contact between that brass plate and your steel chassis to provide the ground?
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I have a question about your front panel brass plate. Does it have a dedicated wire soldered to it that bolts to the chassis? Or, are you relying on the mechanical contact between that brass plate and your steel chassis to provide the ground?
You know Steve I did not do that but it's not a bad idea. So far (keeping fingers crossed) I haven't hd an issue...
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It is an issue that has shown up with plenty of weird symptoms in old Fender amps. It's not likely to become an issue for many years but eventually the brass on steel will develop a higher resistance connection due to galvanic corrosion.
There were similar problems when aluminum wire was first introduced into house wiring, especially in load distribution panels. The lugs worked fine for copper wire but became problematic for the new aluminum wire. New terminals that were rated AL/CU became standard.
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It is an issue that has shown up with plenty of weird symptoms in old Fender amps. It's not likely to become an issue for many years but eventually the brass on steel will develop a higher resistance connection due to galvanic corrosion.
There were similar problems when aluminum wire was first introduced into house wiring, especially in load distribution panels. The lugs worked fine for copper wire but became problematic for the new aluminum wire. New terminals that were rated AL/CU became standard.
Yes that makes since. I know I have pulled out many old brass plates and some were pretty highly corroded. Adding a ground strap is good future insurance Steve, thanks for the heads up...
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Sluckey Mod applied
(http://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/57139b86cf80a18755e90c1f/57c23762d482e921b769b7e4/1472345956812/s-mod.JPG?format=2500w)
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what's your British side based on? And what's the control on the back to next to the outlet plug? Lovely work as usual.
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what's your British side based on? And what's the control on the back to next to the outlet plug? Lovely work as usual.
Hi,
The left channel is based on a Marshall 2203 but I cannot take any credit for that. A very good amp guy here in Nashville showed me that one...
The control in the back is a midrange control for the center channel. 25K pot
Thanks,
Mike