RS127 Brilliance Control

[JMan]

Hello friends,

I would like to share a project I recently completed! This is an RS127-style brilliance control box based on the same section of @ruffrecords wonderful REDD EQ, with a Helios-style line amp for makeup gain. I followed very closely in the footsteps of member @mike (annoying him with many questions along the way), who completed his version of this same project a few years ago. I was inspired by his build and wanted to make one for myself as well. You can see his excellent work in the Redd EQ thread beginning with this post.

This project represented a lot of firsts for me. I had never put something together purely from a schematic (although I should qualify this by saying that I really used Mike's build as a template as well). I had only ever worked with a turret board a couple of times. And I had never designed a PCB, which I did for the line amp -- you can see the journey from total disaster to functional design ("functioning disaster," perhaps?) here. I can't say how much I appreciate all of the help and support I received from the far more experienced people on this forum.

I also want to mention that I used a UTM transformer on the output. @igs is doing a great service to the DIY community, in my opinion! Check out the thread about their transformers here.

Front panel laid out by me, fabricated by Frank.

I hope you all like it! I'm in the middle of finishing up the wiring on a second unit.

 

[TimG]

That looks so cool! Hope they sound good and are fun to use!
Did you choose an off-the-shelf case?

 

[JMan]

Thanks, Tim! I am very impressed by the way this box sounds. All credit goes to Ian for his incredible contributions to our community.

Yes, I used a Hammond 1458C4B. First time working with one of these, and while they're a bit quirky, I have to say I think it is a perfect choice for this application.

 

[TwentyTrees]

Very nice! There's a lot to be said for a box that does just one thing, but does it excellently. Congrats on a great-looking build, and on your PCB design!

 

[mike]

@JMan That's awesome! Excellent work!

 

[JMan]

Thanks, Mike! And thanks for blazing the trail for me!

 

[JMan]

Finished up box #2. Pretty fun to have these in the arsenal!

 

[cjwallgor]

DUDE! These look INCREDIBLE!

Absolutely my favorite EQ EVER on BASS & Vocals!!

PM me if you'd like to build another (or two!). I'd LOVE to have one!!!!

 

[aaquilato]

Thanks, Tim! I am very impressed by the way this box sounds. All credit goes to Ian for his incredible contributions to our community.

Yes, I used a Hammond 1458C4B. First time working with one of these, and while they're a bit quirky, I have to say I think it is a perfect choice for this application.

Ian is THE MAN!!

 

[artheck]

Hi @JMan, this is just amazing work !
So if I understand correctly the curve of the RS127 is basicly the same as the REDD ?
I think I'm going to try build one of this box, I use so much the plugins... !

Thanks

 

[JMan]

Hi @JMan, this is just amazing work !
So if I understand correctly the curve of the RS127 is basicly the same as the REDD ?
I think I'm going to try build one of this box, I use so much the plugins... !

Thanks

That's correct. It's built directly from the Brilliance section of Ian's REDD EQ schematic, and I've included an input transformer and a built-in makeup amplifier to set unity gain on the output. There is some info about the value of the first resistor after the input transformer that is important to getting it to behave like it's meant to (and like the plugin), which can be found in the thread linked below.

Since building this, I have also created a version of the REDD EQ for the 500 series format (with some minor tweaks) that you might be interested in. You can see more information about that here. Although I've closed orders, if this is something that interests you, feel free to send me a PM about how to get PCBs and metalwork.

 

[artheck]

That's correct. It's built directly from the Brilliance section of Ian's REDD EQ schematic, and I've included an input transformer and a built-in makeup amplifier to set unity gain on the output. There is some info about the value of the first resistor after the input transformer that is important to getting it to behave like it's meant to (and like the plugin), which can be found in the thread linked below.

Since building this, I have also created a version of the REDD EQ for the 500 series format (with some minor tweaks) that you might be interested in. You can see more information about that here. Although I've closed orders, if this is something that interests you, feel free to send me a PM about how to get PCBs and metalwork.

Oh Thanks !
I'm just confused how to send PM ? Do I need to be a supporting member ?

 

[thomasdf]

Oh Thanks !
I'm just confused how to send PM ? Do I need to be a supporting member ?

Salut Artheck

Check this link :
https://groupdiy.com/threads/private-messages-conversations-permission-update.82401/

You might also consider presenting yourself in the appropriate section of the forum

 

[artheck]

Oh yes okkay, thanks !

 

[artheck]

So I've collected some informations in the threds you've done.
The 2.4k input resistor is here only if I don't put line input transformer. So if I'm correct: mic input= 2.4k resistor OR line input=10k:10k input transformer ?
For the moment I want to keep it simple and original and not put helios make up gain, so do I need a mic out transformer ?

This schematic is correct ?

 

[JMan]

Include the 2k4 resistor whether you use an input transformer or not. (This also confused me early on). That is the resistor that I mentioned in my earlier post -- you may need to play with its value in order to get the full +/-10dB swing from the EQ. See that thread I linked above and Herbert Rendl's comments on that resistor.

I personally would not think of having a mic input on this unit -- you'd want mic level signal to see a preamp first, which would give you a line level signal to feed into the EQ.

This is a passive EQ, and as such, the overall level drops meaningfully between input and output. Unlike the Softube plugin, which automatically gives you unity gain, you need an amplifier of some sort following the real world circuit. You don't need to use the Helios, there are plenty of options for line amps that will work nicely here. It does not necessarily need to be built into the unit, but you do need one. Since the signal within the circuit is unbalanced, you'll need to consider how you are approaching that on both the input and output. Using a built-in line amp and transformers (or other balancing circuitry) is a convenient way to make sure that all of the unbalancing/balancing happens inside the unit and you never have to think about how to deal with mismatched connections between other balanced, line level gear.

Another idea is to include a built-in makeup amp, but also add a simple little switchable bypass circuit that allows you to send output signal to other external amplifiers directly post-EQ, offering you all the options you could ask for.

The layout that you included in your post is Mike's and is indeed one effective way to connect up the components. If I remember correctly, I used a nearly identical layout for the EQ portion of my units.

 

[artheck]

Great !
Yep I've missed his comment, I need to read it again
Yep it seems more clever to add an amplifier at the output !
It seems weird that the original ones do not have a make up gain... Maybe they where mostly used betwen mic and preamp...

I'm gonna compare your schematic and Mike's one

 

[artheck]

Is there a website where I can get the switches and the 2 transformers ?
By the way, I don't want to put too much messages here, maybe you can send me a message on facebook Arthur Hecky !

 

[JMan]

Great !
Yep I've missed his comment, I need to read it again
Yep it seems more clever to add an amplifier at the output !
It seems weird that the original ones do not have a make up gain... Maybe they where mostly used betwen mic and preamp...

The original ones would have been integrated into a larger signal chain and would have fed an external amplifier like a REDD47 or something similar for make-up gain. They weren't intended for standalone use.

If they were being used for tracking, they would have certainly come after microphone pre-amplification, and then they would have fed an additional amplifier to make up the lost gain from the passive EQ circuit. Definitely not used between mic and preamp. Mic signal needs to see a preamp first. If you want to see a more detailed discussion of this signal chain, I think there is one early in Ian's original Redd EQ thread.

I'm gonna compare your schematic and Mike's one

Mike and I both used the same schematic - the one drawn by Ian/ruffrecords for the full REDD EQ. We simply extracted the Brilliance Control portion of the schematic. If you mean the component layout, just use Mike's. His is well-drawn and nicely documented, and I don't even remember what (if anything) I did differently, but any changes I made were not important from a quality standpoint.

Is there a website where I can get the switches and the 2 transformers ?

Switches are available from many sources. I'd start with Mouser or any of the big retailers, although if you have a local electronics shop, it's nice to support them. For the transformers, you need to decide what make and model you'll use. If building it like I did, the input is 10k:10k and the output is 600:600 (you need to choose an amp circuit that can adequately drive the 600 ohm load; the Helios is a good choice, but as I said before, there are others). You could get both transformers from UTM, who are nice to work with and offer great quality transformers - UTM2571 for input and UTM3581 for output would be good options.

 

[artheck]

Ooh great thanks a lot !
Ookkay UTM seems fine !
I'm gonna check my local electronic shop if they have these kind of switches !