Design Challenge #2

[Chuck D. Bones]

I have not seen the L3 circuit, do you have a schematic? I might have a better idea why they did something if I can see it in context. There is nothing special about positive ground or negative ground.

 

[lrgaraujo]

Sure, there you go:

https://music-electronics-forum.com/filedata/fetch?id=831483&d=1382636822

If I'm not mistaken, they use some servos for biasing (but I could very well be mistaken)

 

[Chuck D. Bones]

Interesting... For 5 out of the 6 inverters in the two CD4007s, they use only the P-channel devices, operating them single-ended. For that configuration, using -15V power makes sense. I believe they get more gain by running the MOSFET stages single-ended. They run the effects loop driver stage push-pull to get the extra current needed. I run all of the CD4007 MOSFET pairs push-pull in my CMOS Distortion. They use servos for biasing the JFET input amp and all of the single-ended stages. Clever design. Complicated, but clever.

 

[lrgaraujo]

Thanks for taking a look, Chuck! From what I could find, it sounds really sweet. From clean to pretty overdriven. I'm kind of obsessed with good sounding SS preamps, so I might try and recreate it (minus the reverb driver and recovery)

 

[cooder]

Aion has the Lab L5 preamp if that's any comparison, I have not looked into any details:
https://aionfx.com/project/l5-preamp/

 

[lrgaraujo]

The L5 is an awesome project! It takes a completely different approach (an OTA is used for distortion), but sounds really good as well! The multifilter stage is also really interesting

 

[Chuck D. Bones]

Right. Nothing like the L3, but interesting.

 

[fig]

Can some kind soul point me to C16 on the schematic? I know it's 100nF, but for some reason I cannot find it.

Thanks in advance.
,

 

[carlinb17]

Can some kind soul point me to C16 on the schematic? I know it's 100nF, but for some reason I cannot find it.

Thanks in advance.
,

Page 9 off of pin 8 of the 4558 schematic says 10nf if your talking about the l5 or

Here for the L3 it is 100nf

 

[fig]

Sorry, I forgot there were schematics flying in every direction..I am building..

...using Matt's board. Maybe I missed a revision?

 

[carlinb17]

Sorry, I forgot there were schematics flying in every direction..I am building..

...using Matt's board. Maybe I missed a revision?

hmmm…maybe it’s like whenever I build something from ikea I have extra parts…

 

[fig]

Good, then you don't see it either, whew!

 

[Chuck D. Bones]

Sorry for the confusion. Matt's board is based on v6.2.1 which has a MID control. Look at post #11 on page 1. C16 was not shown on the schematic; it goes in parallel with C15. Here's an updated schematic.

 

[fig]

Hot dog, thank you sir! I figured it came off of C15 and went to ground, based on the silkscreen.

 

[danfrank]

Hi.
The Maestro Fuzztain (MFTZ-1) uses a 4007 in the Audio path. Lectric FX just came out with a clone board. Their build docs has a schematic. I think the 4007 is used for distortion.

 

[Chuck D. Bones]

Found the MFZT-1 Service Manual.
According to the schematic, the 4007 is used as a voltage-controlled resistor in the compressor. It is not used to make distortion.

 

[Elijah-Baley]

Sorry, I forgot there were schematics flying in every direction..I am building..

...using Matt's board. Maybe I missed a revision?

Excuse me, I seen this schematic and I noticed something weird/knew. Those transistors mosfet type symbol with CD4007 label.
I use Tina TI software to draw schematics, but I can't insert CD4007 to draw the Red Llama schematic.
Is that maybe a sort of trick to "emulate" a CD4007?

Edit: I'm sorry. I confused CD4007 with CD4049UBE. Can I do anything, awnyway to emulate it?

 

[fig]

Excuse me, I seen this schematic and I noticed something weird/knew. Those transistors mosfet type symbol with CD4007 label.
I use Tina TI software to draw schematics, but I can't insert CD4007 to draw the Red Llama schematic.
Is that maybe a sort of trick to "emulate" a CD4007?

Edit: I'm sorry. I confused CD4007 with CD4049UBE. Can I do anything, awnyway to emulate it?

I found the parameters for the TINA-TI MOSFET model, but I'm not sure if it is what your looking for. Do you know if the LTSpice models are compatible?

 

[Chuck D. Bones]

Excuse me, I seen this schematic and I noticed something weird/knew. Those transistors mosfet type symbol with CD4007 label.
I use Tina TI software to draw schematics, but I can't insert CD4007 to draw the Red Llama schematic.
Is that maybe a sort of trick to "emulate" a CD4007?

Edit: I'm sorry. I confused CD4007 with CD4049UBE. Can I do anything, awnyway to emulate it?

When you say "emulate," do you mean simulate? I have LTSpice models for the MOSFETs inside the CD4007 & CD4049. I don't know anything about TINA-TI or if the models are compatible.

 

[Elijah-Baley]

Thanks for your replies, guys.
I'm looking for a CD4049UBE spice to use with Tina TI to draw the schematic of the Red Llama and to see the frequency response, etc. The Red Llama schematic is very simple, and I did some experiments on breadboard, but I'd like to draw it, anyway.
I don't know I can find somewhere the CD4049UBE spice, or I can "build" it with its inner schematic.

I found the parameters for the TINA-TI MOSFET model, but I'm not sure if it is what your looking for. Do you know if the LTSpice models are compatible?

View attachment 17239

Do you think I can use that to get or to create a spice of the CD4049UBE? I don't know if I really can.