mountainhick
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Thank you! You have so many threads/posts, can you link me to the final schematic?
Tremolo questions
- Thread starter mountainhick
- Start date
Thank you! You have so many threads/posts, can you link me to the final schematic?
Want TMI? If you missed it, here's my whole thread about this; lotsa comments, diagrams, and some follow-up.
www.tdpri.com
Practical tips for adding LED rate indication to trem circuit?
I like my trem amps (5G9, 6G2, PR, VC) but it'd be handy to have a visual rate indicator. Merlin shows us how -- *on the schematic*. He says: "By replacing the cathode resistor with an LED we eliminate the need for the large bypass capacitor, and obtain maximum gain and minimum output impedance...
mountainhick
Tele-Afflicted
Want TMI? If you missed it, here's my whole thread about this; lotsa comments, diagrams, and some follow-up.
Practical tips for adding LED rate indication to trem circuit?
I like my trem amps (5G9, 6G2, PR, VC) but it'd be handy to have a visual rate indicator. Merlin shows us how -- *on the schematic*. He says: "By replacing the cathode resistor with an LED we eliminate the need for the large bypass capacitor, and obtain maximum gain and minimum output impedance...
I don't actually, but will have a look. Thanks!
The Merlin article is a different rendition of an oscillator than the Rick-tone circuit. And unfortunately it is not intuitive to me whether to connect from it's anode or cathode to another tube's cathode. It shows the LFO signal at the plate, but uncle doug circuit is coupled from the oscillator's cathode. The VC for example does use the anode output, but then also has a cathode follower after that to the target tube's bias. If the cathode output of the LFO itself is adequate, the single triode version is simpler.
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Definitely don't take my word for it. I don't actually speak LFO, much less Rick-tone or Doug-tone. All I know is I was able to stick a simple red LED on my 6G2 cathode, and it worked, um, brilliantly.
mountainhick
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No one has yet given me reason to not try the doug/ricktone approach, I find the use of a single triode for LFO with cathode coupling to its target appealing, so once I clean up the workbench. I'll try it.
mountainhick
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Proposed Hicktone tremolo:
Look at the schematic again. The plate load for the first triode is fed by the plate of the oscillator. In other words, the oscillator is oscillating the plate voltage of the gain stage.
I modeled just the oscillator alone and the speed range was around 4.7Hz to 10Hz. That's a bit on the fast side.
mountainhick
Tele-Afflicted
I was wondering why it was configured that way. So then it is not the cathode connection alone that affects the gain stage. It is the combo. Thanks for doing the modeling! I thought uncle doug's demo all was pretty fast too. makes sense.
EDIT: frustration was speaking. Maybe I'll make the plate load coupling correction and keep going.
If I switch LFO cap/resistor/pot values to the same as a vibrochamp, should give same range for LFO frequency, no?
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It might be worth trying to adjust the filters.
I think there is a potential for harmonic distortion from the oscillator to be seen/heard in the output from the gain stage. The reason for the smallish .015uF coupling cap, paired with the 500k pot, is to block the LFO from the plate. The F3 is around 19Hz .
Ten Over
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I think Amp Books has a dissertation on the Watkins Dominator, which is where the Rick-Tone tremolo came from.
mountainhick
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Meaning for LFO frequency?
I'd prefer to have input control for signal strength, so that 500K pot isn't needed as such. So maybe a multi stage filter a la Gibson? What would provide the most attenuation of LFO frequency without robbing audio signal?
mountainhick
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Super helpful, thanks!
mountainhick
Tele-Afflicted
Hmm, the filter on the dominator .01uf/500K, has the same cutoff 31hz as the Gibson GA-40, .005uf/1M but the gibson does stack 5 filters in series. Steeper order? 5 in a row seems a lot!
The rick tone uses .015 so lower cutoff at 21hz
mountainhick
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I think I am going to use the dominator circuit. Thank you!
joulupukki
Tele-Holic
Sorry, slow on this. My latest schematic is attached to this post. It’s a 6G16-style tremolo.
https://www.tdpri.com/threads/am-i-measuring-the-output-wattage-correctly.1130563/post-11912213
mountainhick
Tele-Afflicted
Help please!
Question about grounding: (Ground points numbered at the bottom of the drawing)
Because of the physical constraints adding the trem into the same chassis as a reverb circuit without entirely gutting and re-laying out both circuits together, the grounding layout isn't physically in sequence. I am concerned about introducing ground loop hum with things misordered compared what I usually do
Easier options:
1: Group the grounds from the depth pot #11, footswitch #10 and speed pot #8 and ground to chassis.
2: footswitch jack grounded to chassis, and the two pots grounded together with a wire to point #7.
3: Edit/Addendum : footswitch to chassis, group 11 and 12, group all the rest close to being a star point.
Are these bad ideas?
3:
Question about grounding: (Ground points numbered at the bottom of the drawing)
Because of the physical constraints adding the trem into the same chassis as a reverb circuit without entirely gutting and re-laying out both circuits together, the grounding layout isn't physically in sequence. I am concerned about introducing ground loop hum with things misordered compared what I usually do
Easier options:
1: Group the grounds from the depth pot #11, footswitch #10 and speed pot #8 and ground to chassis.
2: footswitch jack grounded to chassis, and the two pots grounded together with a wire to point #7.
3: Edit/Addendum : footswitch to chassis, group 11 and 12, group all the rest close to being a star point.
Are these bad ideas?
3:
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mountainhick
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I think option #3 might be OK:
If anyone understands what I am trying to show, please advise.
Here are the connections shown on the schematic. The actual layout is more convoluted to follow being point to point:
And just the ground wire layout:
If anyone understands what I am trying to show, please advise.
Here are the connections shown on the schematic. The actual layout is more convoluted to follow being point to point:
And just the ground wire layout:
mountainhick
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The actual ground layout:
Almost there:
Almost there:
mountainhick
Tele-Afflicted
Hot damn! It works!!! It sounds really nice with my "Bobcat". Has some nice extra gain available in the first stage, and a reasonable amount of reverb and trem. The trem can get pretty deep, (does have a 5K pot on it) and seems a usable speed range.
I am getting an additional oscillation with reverb level turned way up. Not sure what's going on there, but I don't need to turn it up that high. Could that extra gain stage driving the reverb driver cause an oscillation? It is nowhere near the low frequency of the LFO, so I don't think there' an interaction there.
I need to spend time with it and see whether tweaks will be desired. I will need to reverse wire the depth pot, as it is opposite rotation, clockwise turns down the depth. I might up the value to 3 meg on the speed pot to get some more range.
There is some hum/noise, but everything is wide open.
I'll post the current schematic for the whole unit soon.
I am getting an additional oscillation with reverb level turned way up. Not sure what's going on there, but I don't need to turn it up that high. Could that extra gain stage driving the reverb driver cause an oscillation? It is nowhere near the low frequency of the LFO, so I don't think there' an interaction there.
I need to spend time with it and see whether tweaks will be desired. I will need to reverse wire the depth pot, as it is opposite rotation, clockwise turns down the depth. I might up the value to 3 meg on the speed pot to get some more range.
There is some hum/noise, but everything is wide open.
I'll post the current schematic for the whole unit soon.
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mountainhick
Tele-Afflicted
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