Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: warsavius on February 01, 2023, 07:03:52 am
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I'm modding my 18w TMB (turret board) with a relay switching. I have a question: I need to solder the 68k V1 grid stoppers (3 inputs - 3 of them) very close to the input jacks, then in the 2 nearby relays, then with a shielded cable (grounded on one end) the signal run for 10cm or less to the grids of V1.
I don't have many alternatives because the relay must sit between stopper resistors and tube, unless I add one more relay but It's not space wise for 3 relay.
I'll break the rule "grid stoppers soldered directly to tube socket's pin"... there will be noise issues?
Currently one grid stopper, even if phisically placed close to V1 is not connected directly, its shielded wire go forth and back to the push pull switch in the front panel, but this don't generate any noise. Is this a clue that the "ol good rule" can be broken with a shielded wire?
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Need a schematic
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Need a schematic
Here it is.
(Consider that currently the amp already works fine with this scheme, but it's switched plugging into NORM and with a dpdt Push pull for the PI side - 2 over 3 68k stoppers are soldered directly in the tube socket pins and some shielded cable run to and from the DPDT)
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I'll break the rule "grid stoppers soldered directly to tube socket's pin"... there will be noise issues?
Fender was successfully putting those resistors directly on the input jacks long before that rule was invented.
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I'll break the rule "grid stoppers soldered directly to tube socket's pin"... there will be noise issues?
Fender was successfully putting those resistors directly on the input jacks long before that rule was invented.
Sure you're right: look at this '75 Vibrosonic I'm bringing back to life... but it has no hi gain structure.
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Is this your schematic?
https://www.marshallforum.com/attachments/18w-tmb-with-2203-mode-001-png.124214/
(https://www.marshallforum.com/attachments/18w-tmb-with-2203-mode-001-png.124214/)
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Is this your schematic?
https://www.marshallforum.com/attachments/18w-tmb-with-2203-mode-001-png.124214/
(https://www.marshallforum.com/attachments/18w-tmb-with-2203-mode-001-png.124214/)
sure its my post, i updated the schematic with grid stoppers.