Are there any single EF86 preamps/saturation circuits out there?

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Esppse

Member
Joined
Oct 17, 2019
Messages
9
I'm interested in some pentode saturation off an EF86 tube, line level 2 Bus processing. Would it be okay to only build a REDD47 only up to the EF86 stage? I've seen some lower voltage boxes in the boutique pedal world, but would like to keep this hi voltage.

I dont really understand electronic schematics, so I can't tell what everything after that is doing, but I was looking at the link below and the layout that was posted in that thread. The reason for 1 tube is because I've had Manley Varimu and LA2A/Pultecs cooking next to my mixing position... room tooooooo hot ahhh. Most my outboard is solid state now with the exception of my LaChapell 583 I use to get a beautiful triode saturation color over my mix. I heard the REDD47 did lovely things, but am trying to keep it one tube, also for economic reasons.

https://groupdiy.com/threads/redd-47-mic-preamp.53650/
 
You can but it won't sound anything like a redd 47. There is a feedback network between both tubes. That circuit can't really be simplified any more without significantly changing its character.

It's really hard to make a single tube circuit that interfaces nicely with all the other outboard In a studio.unless you are interested in learning how to design circuits...probably better to just build what you like. Otherwise...welcome too the rabbit hole 😂
 
You can but it won't sound anything like a redd 47. There is a feedback network between both tubes. That circuit can't really be simplified any more without significantly changing its character.

It's really hard to make a single tube circuit that interfaces nicely with all the other outboard In a studio.unless you are interested in learning how to design circuits...probably better to just build what you like. Otherwise...welcome too the rabbit hole 😂
Oh dear I was thinking that, hoping that last tube only brought clean gain.

Ok check this out, this is a simple EF86 circuit that looks easily build able.
Figure 1 seems like it would fit the bill. I would just like to add maybe a pot to drive it into distortion when desired, and output volume too.

Would something like this be worth building, or be underwhelming in sound quality? Just looking for pentode style saturation.

https://www.tube-town.net/cms/?Info/How_To_Use_a_EF86
 
In high-gain pentode mode (where your "pentode sound" is most pronounced), your output impedance tends to get so high that interfacing to elsewhere gets impractical.

So not really possible without additional 'stuff
 
In tubes, distortion is generally directly proportional to signal level. This means that most distortion occurs in the output stage and the least in the input stage (EF86 in your case). You can build a single tube distortion bos but not with an EF86. However, you could use an ECC88 arranged as an SRPP which will give you some nice 'tube tone'.

Cheers

Ian
 
In tubes, distortion is generally directly proportional to signal level. This means that most distortion occurs in the output stage and the least in the input stage (EF86 in your case). You can build a single tube distortion bos but not with an EF86. However, you could use an ECC88 arranged as an SRPP which will give you some nice 'tube tone'.

Cheers

Ian
Agreed. The G-pultec output stage is a great example of this...and it sounds awesome!

https://www.gyraf.dk/gy_pd/pultec/gy_pd_sch.gif
 

Latest posts

Back
Top