Well I guess that pot is fine as far as it goes. If you want the original arrangement/circuit and you don't mind the high ticket I think I would tolerate the shaft sticking out. Though I might cut it off and Dremel a new slot too. All this would be fine except that we're still discussing a part that has nothing to do with thread content.
Announcement
Collapse
No announcement yet.
Twin Reverb - Amp circa 2005 Trem issues
Collapse
X
-
"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
- Likes 1
-
Originally posted by sparkies View Post2.2m sets up a proportional bias so if the -50V is more positive in the circuit, the proportion is going to be to close to the output stage current curve. Giving it more negative bias will increase that proportion ratio.
"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
Comment
-
-
Thank you. And it was posted after it was clearly demonstrated that this was not a bias modulation tremolo. But even if it were the wording and terminology are so nebulous that I questioned myself instead of the phrasings. Like a Jedi mind trick."Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
Comment
-
Originally posted by Chuck H View PostRight. But it was posted after it was clearly demonstrated that this was not a bias modulation tremolo..
I mean it's all obvious from the schematic:
When the LFO is running (footswitch shorting to ground) it's disconnected from the bias supply.
A bias modulating tremolo doesn't need/use an opto.
Just see where the LDR connects.
And even if it were the wording and terminology are so nebulous that I questioned myself instead of the phrasings. Like a Jedi mind trick.
- Own Opinions Only -
Comment
-
Has there ever been a Fender Twin with a bias wiggler circuit? Then you think hmmm maybe something new. But looking at the schematic it explains everything you need to know. Only had a few tremolo amps with bias wiggler. Best sound was from 1959 Tremolox with Jensen speaker. Seems like we just need to clear up the misunderstanding and I have to wonder what the OP was saying. Any additional information is appreciated and I think that might help explain something’s.When the going gets weird... The weird turn pro!
Comment
-
Originally posted by DrGonz78 View PostHas there ever been a Fender Twin with a bias wiggler circuit? Then you think hmmm maybe something new. But looking at the schematic it explains everything you need to know. Only had a few tremolo amps with bias wiggler. Best sound was from 1959 Tremolox with Jensen speaker. Seems like we just need to clear up the misunderstanding and I have to wonder what the OP was saying. Any additional information is appreciated and I think that might help explain something’s.
I did do a two big bottle bias modulated tremolo amp that puts high-ish voltage on the power tubes. I still have to work out some things and dial it in some years later and just haven't gotten to it. Not recommended. I think bias modulated trems are easier to implement and work better with nominal plate voltages. Maybe I'll get this amp just right some day and change my mind but for now I'd say DON'T DO THIS."Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
Comment
-
-
Originally posted by The Dude View Post
It cannot be explained. It is not a correct analysis of the circuit.
As far as the tapped potentiometer, its really not a good circuit and I would set up the bias circuit the older way that is a standard circuit. That is why I was hesitant to show the source of one. Because its nothing special to the circuit and its actually bad practice to design a circuit that current flows through the wiper.. Even though its kind of avoidable, I wouldn't use the wiper on the control in series with the voltage divider like the tapped potentiometer design.
Comment
-
Originally posted by sparkies View Post
Over the years there are two things that have changed. The bias circuit and the gain of the triode that lights the LDR. If the output section bias is correct, then I would play with the gain on the tube. 56K is what was used as the cathode resistor instead of a 100K in this schematic."Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
Comment
-
Originally posted by Chuck H View Post
I haven't seen this. Perusing all the Fender LDR tremolo circuits new and old I can't find any that are using a 56k cathode resistor for the actuator triode. Can you post a link?
AA673 Which has the standard bias circuit. But if you still want balance, I would substitute the 220K feed resistors with a 500K potentiometer.
Comment
-
You beat me to it HelmholtzAll that can do alter the grid load for either side of what should be a balanced circuit.
And I'm not sure what's meant by "one of the hand drawn ones" WRT the schematic. Aren't they all hand drawn? Is this just more nebulous wording to divert the issue?"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
Comment
Unconfigured Ad Widget
Collapse
Comment