ijedouglas wrote: ↑Thu Feb 08, 2024 2:10 pm
Great job! I may have to try one o these
Thanks!! I need to fix the LED location on the faceplate and it should be ready for DIY scene soon once the revisions are made.
I forgot to add that I'll try an OPA2134PA op amp instead of the TL072 to see if that slight top-end loss is recovered. I know the bandwidth of the TL072 is well beyond audible range but I also like the rail-to-rail design of the OPA2134PA. It may also be the 150pf Silver Mica cap I used, a trick that overdrive circuits use in that spot to sweeten the top end. I have an NP0 MLCC cap to go in that place as an experiment as well.
rccolgan wrote: ↑Thu Feb 08, 2024 10:37 am
It's alive! Sounds great. The 2k drive pot indeed works well. If unity is desired, maxing out the drive is necessary in this design. I need to play more with the recovery pot values as 1M goes from grounded signal to full within the first quarter turn. I'm also thinking 1m still might be necessary for proper bias and impedance. I'll need to research more on that.
My favorite feature might be the high headroom flat response recovery boost. With Drive and Recovery maxed out at 100% and boost at 0% (unity) I can tell there is an ever slight drop in level and some top end, which is every FX loop out there, right? . The boost recovers that drop and can add a hell of a punch at the top end of the sweep. I'd say the top end is smoothed out slightly instead of describing it as losing some clarity. Maybe this would be good and "by design" when used in an ODS FX loop.
¯\_(ツ)_/¯
Slick looking box Ryan, love to put my hands on one and compare with my Dlator
Call me crazy but I think I can hear the difference when I swapped out the opamp to a legitimate OPA2134PA. (Lots of knockoffs out there so I always buy from trusted sources). Seems like the noise floor is quieter and the whole signal seems spot on to the bypassed signal now. For reference, I was using my SSS #004 clone with JBL D131 speakers per #004. Lots of detail and bite available for bleeding ears.
Another new thing I figured out is that I can simply add a signal into the RETURN instead of the INPUT and use the boost function alone. I was trying to isolate what part of the circuit might be softening the upper part of the frequency spectrum when I stumbled on this. I'll have to do a BODE plot with my scope next to verify the frequency range outside of the calculated flat response.
@Erwin, I'm teaching Shelby how to solder so I'll send you one of her units! Just kidding... she has no interest in this stuff right now unless I was making one for Taylor Swift
rccolgan wrote: ↑Thu Feb 08, 2024 10:37 am
It's alive! Sounds great. The 2k drive pot indeed works well. If unity is desired, maxing out the drive is necessary in this design. I need to play more with the recovery pot values as 1M goes from grounded signal to full within the first quarter turn. I'm also thinking 1m still might be necessary for proper bias and impedance. I'll need to research more on that.
My favorite feature might be the high headroom flat response recovery boost. With Drive and Recovery maxed out at 100% and boost at 0% (unity) I can tell there is an ever slight drop in level and some top end, which is every FX loop out there, right? . The boost recovers that drop and can add a hell of a punch at the top end of the sweep. I'd say the top end is smoothed out slightly instead of describing it as losing some clarity. Maybe this would be good and "by design" when used in an ODS FX loop.
¯\_(ツ)_/¯
Wow what a great job, I'll be after those PCBs as soon as you have the final implementation! I'm going to build a K-lator so I'll be able to compare all 3 Dumble style effects buffers
rccolgan wrote: ↑Thu Feb 08, 2024 10:37 am
It's alive! Sounds great. The 2k drive pot indeed works well. If unity is desired, maxing out the drive is necessary in this design. I need to play more with the recovery pot values as 1M goes from grounded signal to full within the first quarter turn. I'm also thinking 1m still might be necessary for proper bias and impedance. I'll need to research more on that.
My favorite feature might be the high headroom flat response recovery boost. With Drive and Recovery maxed out at 100% and boost at 0% (unity) I can tell there is an ever slight drop in level and some top end, which is every FX loop out there, right? . The boost recovers that drop and can add a hell of a punch at the top end of the sweep. I'd say the top end is smoothed out slightly instead of describing it as losing some clarity. Maybe this would be good and "by design" when used in an ODS FX loop.
¯\_(ツ)_/¯
Wow what a great job, I'll be after those PCBs as soon as you have the final implementation! I'm going to build a K-lator so I'll be able to compare all 3 Dumble style effects buffers
Thanks!! Wow! I'm looking forward to that review! My understanding of the Klator circuit is that it's a straightforward JFET adaptation of the Dumbleator circuit (or at least the schematics that I've seen). It works, but for me, I would have added more to the circuit to mimic tube behavior, Miller effect, etc. This project with OpAmps is much more fun
This looks amazing Ryan, astonishing how fast you developed such a nice product. Even Dumble approved fonts on the PCB's. With a TL062 this would probably even run of a battery.
I'm curious to see how the frequency response of the loop is and how well it works with long cables.
rccolgan wrote: ↑Thu Feb 08, 2024 10:37 am
It's alive! Sounds great. The 2k drive pot indeed works well. If unity is desired, maxing out the drive is necessary in this design. I need to play more with the recovery pot values as 1M goes from grounded signal to full within the first quarter turn. I'm also thinking 1m still might be necessary for proper bias and impedance. I'll need to research more on that.
My favorite feature might be the high headroom flat response recovery boost. With Drive and Recovery maxed out at 100% and boost at 0% (unity) I can tell there is an ever slight drop in level and some top end, which is every FX loop out there, right? . The boost recovers that drop and can add a hell of a punch at the top end of the sweep. I'd say the top end is smoothed out slightly instead of describing it as losing some clarity. Maybe this would be good and "by design" when used in an ODS FX loop.
¯\_(ツ)_/¯
Wow what a great job, I'll be after those PCBs as soon as you have the final implementation! I'm going to build a K-lator so I'll be able to compare all 3 Dumble style effects buffers
Thanks!! Wow! I'm looking forward to that review! My understanding of the Klator circuit is that it's a straightforward JFET adaptation of the Dumbleator circuit (or at least the schematics that I've seen). It works, but for me, I would have added more to the circuit to mimic tube behavior, Miller effect, etc. This project with OpAmps is much more fun
Well I bought a 1590 BB box yesterday, so I'm getting ready for your Box a Lator! Please let us know as soon as you decide on a final BOM, so I can start to gather a few parts. I've got everything for Klator build now.
Seems like fine tuning the perfect IC will be the icing on the cake for this excellent project.
rootz wrote: ↑Sat Feb 10, 2024 12:55 am
This looks amazing Ryan, astonishing how fast you developed such a nice product. Even Dumble approved fonts on the PCB's. With a TL062 this would probably even run of a battery.
I'm curious to see how the frequency response of the loop is and how well it works with long cables.
Thanks! Here are some interesting plots. The one with the messy cables is through a 20ft cable from Amazon back through the loop onto itself. The input signal is ~0db at 780mv pk2pk
The sinewave one is slamming the input with 6v pk2pk, and boosting until the output signal starts to clip with the OPA2134PA. Lots of headroom for the input and the output. Pay attention to the vertical scale between the two. Channel 1 is the input and channel 2 is the output
You do not have the required permissions to view the files attached to this post.
Fair point! Thanks for chiming in! I think a 220k to ground right at the input of both sides of the op amp would be a good balance of predictable bias and Johnson noise. I'll do some math later too. Easy to mod these boards I have as well. Good thing I only ordered 5x.
Now I'll have to leave this as-is built unit on for a couple of days to see if it gets wild
Fair point! Thanks for chiming in! I think a 220k to ground right at the input of both sides of the op amp would be a good balance of predictable bias and Johnson noise. I'll do some math later too. Easy to mod these boards I have as well. Good thing I only ordered 5x.
Now I'll have to leave this as-is built unit on for a couple of days to see if it gets wild
Ryan what are those knobs? I'm going to the knob shop on Tuesday and like to get some similar cool ones
Also if you do have a copy of the basic K-lator schematic, that would be appreciated, it used to be on Brown Note but is long gone, I think.
Fair point! Thanks for chiming in! I think a 220k to ground right at the input of both sides of the op amp would be a good balance of predictable bias and Johnson noise. I'll do some math later too. Easy to mod these boards I have as well. Good thing I only ordered 5x.
Now I'll have to leave this as-is built unit on for a couple of days to see if it gets wild
Ryan what are those knobs? I'm going to the knob shop on Tuesday and like to get some similar cool ones
Also if you do have a copy of the basic K-lator schematic, that would be appreciated, it used to be on Brown Note but is long gone, I think.
Fair point! Thanks for chiming in! I think a 220k to ground right at the input of both sides of the op amp would be a good balance of predictable bias and Johnson noise. I'll do some math later too. Easy to mod these boards I have as well. Good thing I only ordered 5x.
Now I'll have to leave this as-is built unit on for a couple of days to see if it gets wild
Ryan what are those knobs? I'm going to the knob shop on Tuesday and like to get some similar cool ones
Also if you do have a copy of the basic K-lator schematic, that would be appreciated, it used to be on Brown Note but is long gone, I think.
Unfortunately I cannot find the schematic now either. I'll keep digging
Thanks Ryan, that's really great!
I have got a BB equivalent box that is 34mm high, higher than the 30mm Hammond , I can't find a 42mm BBS locally, will I have enough height? Thanks.
rogb wrote: ↑Sun Feb 11, 2024 6:00 pm
Ryan what are those knobs? I'm going to the knob shop on Tuesday and like to get some similar cool ones
Also if you do have a copy of the basic K-lator schematic, that would be appreciated, it used to be on Brown Note but is long gone, I think.
Unfortunately I cannot find the schematic now either. I'll keep digging
Thanks Ryan, that's really great!
I have got a BB equivalent box that is 34mm high, higher than the 30mm Hammond , I can't find a 42mm BBS locally, will I have enough height? Thanks.
The BB should be good still. You just need to remove the bottom nut on your footswitch. I'm building my next one in a BB size
. The boost recovers that drop and can add a hell of a punch at the top end of the sweep. I'd say the top end is smoothed out slightly instead of describing it as losing some clarity. Maybe this would be good and "by design" when used in an ODS FX loop. 
