sluckey wrote: ↑Thu Jan 09, 2020 12:09 am
You're getting closer to the Supro circuit. Now, take it all the way! Connect the trem output to V1 pin 3 rather than V3 pin 3. And use a 1.5K with 35µF on the cathode of V1. I believe the 35µF cap also has a smoothing effect on the trem signal. And injecting the trem in the first preamp stage as Supro did will result in a stronger effect.
Take a look at the Supro schematic I linked. I know this circuit produces a strong smooth trem effect. Xtian has built this same circuit. Maybe he'll chime in.
Thanks Sluckey! I appreciate all the help. Yes, I will take it all the way! I am torned between S6698 and the S6424. I just realised they have similar topology, just different values on the driver...Maybe I will go with alligator clips between the two to see how different they sound..
As far a the connection my trem is already at V1 PIN3, so no need to worry there. As far as the cathode of V1, 35uF will probably give me a lot of bass on the tonestack, and I really don't like too much bass on my amps. I was actually wondering if I should change the 1.5K to 820R as Erwin suggested in order to match the voltages of both triodes on the tonestack...
Now that I got the red LED I was also wondering if it would be a good candidate to replace the cathode of the LFO triode (in case of the S6698). I also am thinking of going 500Kb on the Intensity, like you did on the S6424.
Just ordered some 0.03uF and 1.5M which I don't have..Will keep you posted.
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No decision is taken lightly. I reverted back to some Ry Cooder reference live show, and was watching Santa Cruz 1987. Besides the Borderline (on the left) he had 2 heads pilled on top of each other on top of a Musicman cab (on the right).
After some further researching I found a post from Kimock, some may be familiar with the name: "Looked to me like a Supro Statesman or possibly Sportsman in front of a HiWatt power amp on a 2x12, and some Dumble type thing" https://www.thegearpage.net/board/index ... r.1207208/
So Ry was either using a Supro S6698 Sportsman or a Supro S6699 Statesman (both amps below for reference).
After checking some more footage of that show I think he indeed had a S6699 Statesman (3 knobs on the left instead of 4 and proximity of the knobs). Attached the schematic of S6699 for future reference, if anoyone wants to build that pre into a Hiwatt .
After checking the schematic of S6699 I noticed it has the same tremolo as the S6698 with some minor variatons (ie) .05uF across the Intensity and .01uF before the 2.2M). Given I wanted a Ry tremolo, I will try this one but will probably add the LED to the LFO cathode. Can anyone explain the reason for the extra .05uF on the Intensity pot (making it 2 in total)?
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Can anyone explain the reason for the extra .05uF on the Intensity pot (making it 2 in total)?
It's for smoothing of the tremolo signal.
There's more to the "Supro" style tremolo than you are seeing. You have been concentrating on the osc/driver circuit and then simply injecting the trem signal into the cathode of a preamp tube. But there's more! Look on the Supro schematic, specifically look at the plate circuit of the preamp tube. See the extra RC filter on the plate? That's an important part of the Supro tremolo. The extra RC filter helps remove any remnants of the actual trem signal such that only the guitar signal with amplitude variations is left. You will see this filter in all the Supro schematics. Heck, the S6698 actually has two rc filters for even better removal of the trem signal. You may want to look at the Vox AC-15 circuit. It has a five pole filter!
This filter is a necessary part of this trem circuit. But it also affects the sound of the guitar signal. So it actually becomes a part of "that sound" for a particular amp. You may not like how it affects the sound of your ODS amp.
The hassles you're having are all part of the reason I decided to find a better circuit, one that doesn't have the pumping issues of this Supro style, or the ticking issues of a neon optocoupler (Fender AB763), or the bias interaction with the power tube bias vary trem (older Fender). That's why my Trem-O-Nator came to be. It produces a strong, smooth trem effect that has none of the issues I just mentioned. An it can be easily adapted to almost any amp with minimal effect on the sound of the amp, just good, smooth tremolo effect.
I think you should look at this link and also follow the link to my Bandmaster to see a real world application of the Trem-O-Nator. Give the circuit some consideration. Heck, give it a try. You'll probably quit torturing yourself about Cooder.
Thanks for pointing this detail about the extra RC Filter Supro amps Steve. I completely missed it!!! I appreciate the guidance and also many thanks for the suggestion about your improved blackface tremolo. I may resort to that when my options run out, but I am stuck in my mind to make this work
I went back to the Gibson G2RVT schematic and actually just realised that this is the exact same entrance (driver) used on the Borderline tremolo (as per schematics posted). The Supro reference was a mistake of my own.
On the Gibson the signal comes from the Grid (PIN5) to the Intensity, Plate (PIN6) has no resistor and is getting 235V and cathodes (PIN4) are shared with the tonestack....what am I missing? The .005/1M network?
EDIT: I just increased my voltage at the driver to 226V
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On the Gibson the signal comes from the Grid (PIN5) to the Intensity, Plate (PIN6) has no resistor and is getting 235V and cathodes (PIN4) are shared with the tonestack....what am I missing?
You have that backwards. The trem signal comes from the INT pot, travels left to the grid of V2 cathode follower. V2's cathode is connected to the cathode of V1 preamp,same as the supro circuit. But look at the plate of V1. There are five .005 caps and five 1M resistors instead of the more common one coupling cap. This is a five pole RC filter and it's purpose is to filter out the trem signal from the guitar signal. YOU NEED THAT FILTER FOR THIS TYPE TREM CIRCUIT! And you can bet your ass that it will affect the guitar tone. You may not like how it affects the tone.
You gotta quit bouncing around with all these trem circuits. They are all basically the same. Pick one and build the whole circuit, not just the osc/driver. All the parts work together, including the big cathode cap and the RC filters on the preamp plate.
On the Gibson the signal comes from the Grid (PIN5) to the Intensity, Plate (PIN6) has no resistor and is getting 235V and cathodes (PIN4) are shared with the tonestack....what am I missing?
You have that backwards. The trem signal comes from the INT pot, travels left to the grid of V2 cathode follower. V2's cathode is connected to the cathode of V1 preamp,same as the supro circuit. But look at the plate of V1. There are five .005 caps and five 1M resistors instead of the more common one coupling cap. This is a five pole RC filter and it's purpose is to filter out the trem signal from the guitar signal. YOU NEED THAT FILTER FOR THIS TYPE TREM CIRCUIT! And you can bet your ass that it will affect the guitar tone. You may not like how it affects the tone.
You gotta quit bouncing around with all these trem circuits. They are all basically the same. Pick one and build the whole circuit, not just the osc/driver. All the parts work together, including the big cathode cap and the RC filters on the preamp plate.
Noted with thanks regarding the five pole RC filter. Up until now I only had experience with the Blackface trem. Did no expect that most of the other trems would have such an impact on the non-trem path, but I guess there is only one way to learn and I appreciate your help... Still mind boggling how HAD implemented this...The Harmonic trem is one on my bucket list to try..maybe in the future..
Point taken...Will give your Trem-O-Nator a go.....seems like a good solution and thanks for suggesting it.....I just need the pots and the Vactrol.
Cadmium & ROHS. And vactrols are now difficult to source. Search around smaller shops supporting DIY synthesizer community. I have recently seen some with VTL5C1 for sale.
Best .. Ian
Last edited by didit on Fri Jan 10, 2020 12:01 pm, edited 2 times in total.
That's almost right. Make these changes in the attached pic. While waiting for your VTL5C1 to arrive go ahead and remove the 25µF cap and 4.75K resistor from pin 3. Now install a 10K between pin 3 and ground. Temporarily connect a red LED across that 10K. Be sure the cathode connects to ground. Now fire up the amp. The LED should blink for all settings of the speed pot. If not, move the B+ connection to the screen node and try again. Once the LED is blinking the circuit is ready to replace the LED with the VTL5C1. Be sure the cathode (negative) is connected to the footswitch jack. The footswitch jack should be a type with a shunt terminal such as Switchraft 12A if you want to use the trem without a footswitch connected.
The only part you may have to diddle with is the INT pot value and you may need a resistor connected between the INT pot and the top of the MV pot. I'm assuming the MV is just before the PI? That's where I'd put it.
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sluckey wrote: ↑Fri Jan 10, 2020 3:31 pm
That's almost right. Make these changes in the attached pic. While waiting for your VTL5C1 to arrive go ahead and remove the 25µF cap and 4.75K resistor from pin 3. Now install a 10K between pin 3 and ground. Temporarily connect a red LED across that 10K. Be sure the cathode connects to ground. Now fire up the amp. The LED should blink for all settings of the speed pot. If not, move the B+ connection to the screen node and try again. Once the LED is blinking the circuit is ready to replace the LED with the VTL5C1. Be sure the cathode (negative) is connected to the footswitch jack. The footswitch jack should be a type with a shunt terminal such as Switchraft 12A if you want to use the trem without a footswitch connected.
The only part you may have to diddle with is the INT pot value and you may need a resistor connected between the INT pot and the top of the MV pot. I'm assuming the MV is just before the PI? That's where I'd put it.
That is great! Thanks for the correction. I will try with the red LED tonight. Just to be sure with the flat side of the LED (the cathode) will be connected to ground and the other side to the 10K?!
My footswitch doesn't have the shunt, it is like a balckface, so the trem only works with the footswitch, but good to know of this alternative. I may come back to this after all is working.
My MV is as per ODS, just before the PI. I had placed the AB763 tremolo on another ODS and didn't need to add a resistor between the INT pot and the top of the MV pot, but will keep it in mind for this. What should I expect to hear that would trigger the need for the added resistor? But we can check that when it is all done...on my end
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I will try with the red LED tonight. Just to be sure with the flat side of the LED (the cathode) will be connected to ground and the other side to the 10K?!
Yes. Just pretend the red LED is the LED inside the VTL5C1, except you can see it.
What should I expect to hear that would trigger the need for the added resistor? But we can check that when it is all done...on my end
If the trem is too strong to use at full intensity you can add the resistor. If the circuit decreases the guitar level too much with the INT turned to zero, then use a larger value pot. All this will be determined experimentally (tweaked) after the circuit is up and running. If you are lucky you won't have to do anything.
I will try with the red LED tonight. Just to be sure with the flat side of the LED (the cathode) will be connected to ground and the other side to the 10K?!
Yes. Just pretend the red LED is the LED inside the VTL5C1, except you can see it.
What should I expect to hear that would trigger the need for the added resistor? But we can check that when it is all done...on my end
If the trem is too strong to use at full intensity you can add the resistor. If the circuit decreases the guitar level too much with the INT turned to zero, then use a larger value pot. All this will be determined experimentally (tweaked) after the circuit is up and running. If you are lucky you won't have to do anything.
All changes are done. The LED is flashing beautifully. At 225V or at 200V I get the full range flashing, so will just need to decide once I have the VTL which range I prefer. Now the only thing that needs addressing is the Intensity that at Zero kills the master too, so I get no volume in the amp. From 9 o’clock to zero it starts reducing the volume of the amp
There is some drop in gain as well when the circuit is connected versus when it is disconnected (I have a toggle between the master and the tremolo) but anyone who uses a AB763 would be used to this and therefore not a concern.
Now how can it be possible that I hear the trem and it is not connected at all to the circuit? Maybe via the supply? Or via the heaters? Recording attached with master at Max.
By the way my footswitch actually has a shunt!
EDIT: figured out, the alligator clips causing cross talk. At least I can hear the range
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Last edited by Bombacaototal on Fri Jan 10, 2020 9:10 pm, edited 1 time in total.
Now the only thing that needs addressing is the Intensity that at Zero kills the master too, so I get no volume in the amp.
Well, you don't have the INT wired according to the schematic. Recheck carefully. The wiper of the INT does not go to the MV.
There's gonna be a drop in guitar signal (gain) because you are putting a 250K pot parallel to your MV pot. A larger INT pot and/or a resistor between the INT and MV pots can help with that. But it's too soon to start juggling that. Wait on the VTL5C1.
Now the only thing that needs addressing is the Intensity that at Zero kills the master too, so I get no volume in the amp.
Well, you don't have the INT wired according to the schematic. Recheck carefully. The wiper of the INT does not go to the MV.
There's gonna be a drop in guitar signal (gain) because you are putting a 250K pot parallel to your MV pot. A larger INT pot and/or a resistor between the INT and MV pots can help with that. But it's too soon to start juggling that. Wait on the VTL5C1.
EDIT: figured out, the alligator clips causing cross talk. At least I can hear the range
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