Just as a side note, there was also a 3094 (single) and 13600 (dual) with some differences between them and the 3080/13700 respectively - from memory I think the EHX Small Stone used the 3094, and I'm sure I've seen the 13600 in various early 80s devices - they're not necessarily *not* straightup swappable with a 13700, but not necessarily so either... something to do with the buffer design being different internally.
I have been experimenting with the oberheim obx filter using the 13700 in place of the 3080. Ive also implemented the onboard buffers instead of using opamp buffers in the obx design. Works well for what I want.
I saw many ladder filter using and OTA as difference amplifier for their output. I've always assumed it was both for the sound (as you said, the tanh property) and for a low part count and low cost "INA" since it can be used on open loop configurations. In more recent Moog schematics there are various 13700 placed around with a fixed Iabc that were there just in case they needed more VCAs before production or for quick prototyping
Thanks for all the deep insight! BTW: can you (if time allows) explain the working of the Colorsound inductor-less Wah)? I've finished building one, but don't really understand, how the wah sound is created.
It's what's called a twin-T notch filter -- but they put it in a negative feedback loop so it basically inverts the transfer function and turns it into a band boost (think of the BJT base as the negative input of a primitive op amp and there emitter as the positive input).
@@Lantertronics Thanks. Is there any simple way to calculate the Edge Frequencies and the Q-Factors? I measured the circuit with a noise signal and found fl=200Hz, fh=2000Hz and Q between 2.4 and 5. When iI dial that into my KPA, the Wah Sound is not complete right. Am I missing something?. OK:I found a site, where could calculate the required info(FH 173Hz, FH 1691,QL=5,QH=1.3). The calculator though doesn't have the 33k resistor, going between the LP Cap and ground). The Wah created with the new values sounds quite right. Any idea, wheat this additional resistor's function could be?
In my understanding the 3080 in DIP is in production again. You can find them at small retailers like Thonk. Also, the DIP version of the 13700 is out of production, the SMT version is not.
Yes, I have used the Alfa 3080ies for my Oberheim Eight Voice Clone Project. I don’t have an original SEM to compare it to, but I am very pleased with the Sound!@@Lantertronics
@@Lantertronics Yes. They also make clones of the old CEM line IC's and some other stuff like matched transistor pairs in metal cans and a quad OTA (AS13704).
In that wasp filter you flash at the very end, the power supply is +-2.5v. Could you replace the 3080 with a 13700 in this case? According to the specs the LM13700 needs at least +-4.75, so it seems that is another difference between the to OTAs.
Are you taking us for a ride here, Prof? ;) As for the VCF not using the OTA for Q control, I have seen one of them which does that, was it in the MemoryMoog perhaps...
Professor can you contact Texas Instrument and ask them to put the the LM13700 in a dip8 package to save space on the pcb's (without the darlingtons and terminate the unwanted things on the silicon die them inside the package). that would be really useful if you design 4HP modules, witch i do. Now i need to stack pcb's with headers because a bit of the circuit doesn't fit due to the dip16 package and routing becomes a hell of a job.
If you need to save space I'd go for the surface mount package (yes, I know it's more of a pain to deal with). Alas, there wouldn't really be enough of a market to justify TI retooling for a new version of the same die in a different package.
@@Lantertronics Ya, maybe something conservative, but i like to be able to replace/recover if i brake it or the PCB doesn't work. during the pandemic the dip version became instinct at mouser and at some point they announced some 30.000 would be delivered in 2 tranches and than i got new ones. 25.601 are available now, so around 4.400 have been sold in the last 10 months or less. Would still be cool if TI would do so, but there is no form of contact possible, it all goes via a external customer agency, than you're sure it will lead to no where. i investigated.
@@AnalogDude_ You could use a SMT to DIP adapter board. I do this quite a bit myself when prototyping or for trying different OPAs in kits that used a DIP part, originally.
Does the hyperbolic distortion characteristics of the 3080 simulate the distortion characteristics of basic dual triode preamplifier tubes like the 12ax7?
Although a distortion circuit using this tanh character will probably sound nice enough - tanh is often used in software distortion, because of its nice sound, as well its uncomplicated use: just drop in a tanh and you're golden. It is, however, symmetrical, so it generates odd harmonics rather than even - this can be easily remedied in software though, and probably in circuitry as well.
Just as a side note, there was also a 3094 (single) and 13600 (dual) with some differences between them and the 3080/13700 respectively - from memory I think the EHX Small Stone used the 3094, and I'm sure I've seen the 13600 in various early 80s devices - they're not necessarily *not* straightup swappable with a 13700, but not necessarily so either... something to do with the buffer design being different internally.
Nice clarification about the differences between those two.. It would be awesome if you could go into the linearization diodes one day.
The "frequency Central" Raging Bull by electric druid is doing the same by using a OTA.
It's now a +/-3.50€ part.
This video was one heck of a roller coaster ride! 🎢😁
Keep up the great content, Aaron! 👍
I have been experimenting with the oberheim obx filter using the 13700 in place of the 3080. Ive also implemented the onboard buffers instead of using opamp buffers in the obx design. Works well for what I want.
Wow, didn't notice there was such difference... I need to check some of my schematics, it might explain some behaviours! Thank you for your videos!
I saw many ladder filter using and OTA as difference amplifier for their output. I've always assumed it was both for the sound (as you said, the tanh property) and for a low part count and low cost "INA" since it can be used on open loop configurations. In more recent Moog schematics there are various 13700 placed around with a fixed Iabc that were there just in case they needed more VCAs before production or for quick prototyping
Huh... having various 13700s around "just in case" they needed a VCA is really interesting!
@@Lantertronics never enough VCAs!
I just want to mention that you can buy as3080 for €3.60, almost as much as in $
Intro 💯
Thanks!
Thanks for all the deep insight! BTW: can you (if time allows) explain the working of the Colorsound inductor-less Wah)? I've finished building one, but don't really understand, how the wah sound is created.
It's what's called a twin-T notch filter -- but they put it in a negative feedback loop so it basically inverts the transfer function and turns it into a band boost (think of the BJT base as the negative input of a primitive op amp and there emitter as the positive input).
@@Lantertronics Thanks. Is there any simple way to calculate the Edge Frequencies and the Q-Factors? I measured the circuit with a noise signal and found fl=200Hz, fh=2000Hz and Q between 2.4 and 5. When iI dial that into my KPA, the Wah Sound is not complete right. Am I missing something?.
OK:I found a site, where could calculate the required info(FH 173Hz, FH 1691,QL=5,QH=1.3). The calculator though doesn't have the 33k resistor, going between the LP Cap and ground). The Wah created with the new values sounds quite right. Any idea, wheat this additional resistor's function could be?
just at the right time in the right place
In my understanding the 3080 in DIP is in production again. You can find them at small retailers like Thonk. Also, the DIP version of the 13700 is out of production, the SMT version is not.
Oh interesting! Apparently there's a company called Alfa making them as the CA3080.
Yes, I have used the Alfa 3080ies for my Oberheim Eight Voice Clone Project. I don’t have an original SEM to compare it to, but I am very pleased with the Sound!@@Lantertronics
@@Lantertronics Yes. They also make clones of the old CEM line IC's and some other stuff like matched transistor pairs in metal cans and a quad OTA (AS13704).
@@PWMaarten Excellent!
nice thanks!
Why are OPA860 and 861 not in the conversation?
In that wasp filter you flash at the very end, the power supply is +-2.5v. Could you replace the 3080 with a 13700 in this case? According to the specs the LM13700 needs at least +-4.75, so it seems that is another difference between the to OTAs.
Are you taking us for a ride here, Prof? ;)
As for the VCF not using the OTA for Q control, I have seen one of them which does that, was it in the MemoryMoog perhaps...
Professor can you contact Texas Instrument and ask them to put the the LM13700 in a dip8 package to save space on the pcb's (without the darlingtons and terminate the unwanted things on the silicon die them inside the package). that would be really useful if you design 4HP modules, witch i do.
Now i need to stack pcb's with headers because a bit of the circuit doesn't fit due to the dip16 package and routing becomes a hell of a job.
If you need to save space I'd go for the surface mount package (yes, I know it's more of a pain to deal with).
Alas, there wouldn't really be enough of a market to justify TI retooling for a new version of the same die in a different package.
@@Lantertronics Ya, maybe something conservative, but i like to be able to replace/recover if i brake it or the PCB doesn't work. during the pandemic the dip version became instinct at mouser and at some point they announced some 30.000 would be delivered in 2 tranches and than i got new ones. 25.601 are available now, so around 4.400 have been sold in the last 10 months or less.
Would still be cool if TI would do so, but there is no form of contact possible, it all goes via a external customer agency, than you're sure it will lead to no where. i investigated.
@@AnalogDude_ You could use a SMT to DIP adapter board. I do this quite a bit myself when prototyping or for trying different OPAs in kits that used a DIP part, originally.
@@christopherventer6391 Ya, i recently got a few SOIC8 to dip8 adapters, but not yet used them. : )
Does the hyperbolic distortion characteristics of the 3080 simulate the distortion characteristics of basic dual triode preamplifier tubes like the 12ax7?
My guess would be: not exactly, as valves follow a 3/2-power law, rather than exponential
Although a distortion circuit using this tanh character will probably sound nice enough - tanh is often used in software distortion, because of its nice sound, as well its uncomplicated use: just drop in a tanh and you're golden. It is, however, symmetrical, so it generates odd harmonics rather than even - this can be easily remedied in software though, and probably in circuitry as well.