Reddish 500 EQ

[JMan]

@thelivingroom gave an excellent explanation.

Basically, pin 2 is the wiper, so if you clip or disconnect that, you are left simply with a fixed resistor of 5k ohms or whatever total resistance of the trimmer you chose to use. Instead, you essentially want to create a rheostat with pins 1 and 2 in order to dial in the amount of resistance desired. You could leave pin 3 disconnected, but it is generally better practice to tie 2 & 3 together in this scenario. Because I'm a visual person, I've taken the liberty of sketching the connections that thelivingroom already described.

FWIW, I've now built a unit using a 1k resistor for R0 based on Herbert's feedback and found that it achieved a very accurate result. I'd suggest pre-trimming to 1k, you might find that you don't even need to adjust it.

 

[thelivingroom]

@thelivingroom gave an excellent explanation.

Basically, pin 2 is the wiper, so if you clip or disconnect that, you are left simply with a fixed resistor of 5k ohms or whatever total resistance of the trimmer you chose to use. Instead, you essentially want to create a rheostat with pins 1 and 2 in order to dial in the amount of resistance desired. You could leave pin 3 disconnected, but it is generally better practice to tie 2 & 3 together in this scenario. Because I'm a visual person, I've taken the liberty of sketching the connections that thelivingroom already described.

FWIW, I've now built a unit using a 1k resistor for R0 based on Herbert's feedback and found that it achieved a very accurate result. I'd suggest pre-trimming to 1k, you might find that you don't even need to adjust it.

Exactly, Pins 1 and 2 are what you want. I only tack 2 to 3 because 2 usually isn’t long enough to make it to the pad.

Thanks for the better explanation and drawing! My brain is in troubleshooting hell right now.

 

[Volume11]

You’re welcome! I forgot to mention to get 3266Y, the one with inline pins.

View attachment 135866

Thats what I ordered, luckily. I have to admit, the data sheet confused the hell out of me

 

[MasterTheSound]

They are looking very pretty. I didn’t find the colored middle knob at tayda but anyone got an idea of the color it would be called? Figured I’d paint it myself. Thanks again for this build it has been awesome and sounds so good. Now to finish the next pair. Might try the Carnhill and Cinemag option next build. View attachment IMG_1338.jpeg

 

[JMan]

They are looking very pretty. I didn’t find the colored middle knob at tayda but anyone got an idea of the color it would be called? Figured I’d paint it myself. Thanks again for this build it has been awesome and sounds so good. Now to finish the next pair. Might try the Carnhill and Cinemag option next build. View attachment 135946

Looking good!

Regarding the grey colored knobs, they are available from a few suppliers. Here's one in the US.

I'm not sure what exact shade of grey the knob is, but I will say this -- I think if you find a paint that matches closely enough, that's fine. I have purchased the ones linked above and I have also purchased (for unrelated purposes quite a few years ago) knobs directly from Chandler, and the Chandler knobs have more of a blueish-grey hue while the ones I've seen available from retailers are more of a straight ahead grey. So there's variability in what's out there, and I think "close enough" is the same as "correct" in this case. Something like a RAL 7031/Pantone 445 would get you in the right ballpark, I imagine, or RAL 7046/Pantone 430 (the former being a darker shade and the latter being on the lighter end).

 

[Volume11]

Anyone else having any issues with the push buttons lining up? They are soldered straight and flush on the board, but crooked still.

 

[JMan]

Are you referring to the unit on the right, where one of the button caps is seated a little "off" relative to the other? I also experienced this. I think it is a matter of the F2UEE switches themselves having a little bit of play and/or some mechanical margin of error. You can re-flow a solder joint or two and manipulate the body of the switch by hand to finesse it into alignment.

 

[Volume11]

Are you referring to the unit on the right, where one of the button caps is seated a little "off" relative to the other? I also experienced this. I think it is a matter of the F2UEE switches themselves having a little bit of play and/or some mechanical margin of error. You can re-flow a solder joint or two and manipulate the body of the switch by hand to finesse it into alignment.

Yeah that's it. I'll give it a go, thanks!

 

[slipperyflax]

The knobs will be replaced, this was just what I had in my drawers. Two things I encountered on final assembly:

1. To accommodate the output transformer (UTM3524) I had to sand lightly on the PCB since the transformer wouldn't properly sit in the hole.
2. One bracket had too big holes to hold the transformer screws; they just went through. Solved it by further counter sink the holes and then use a small washer so that the screw didn't go through. It means however that the screws sits just a tad proud but it seems to work fine.

AWESOME project! Had a blast building these. Now I'm gonna make myself familiar with them

 

[JMan]

Awesome work! So glad you enjoyed building them.

I'm surprised that the output transformer needed additional sanding, this version of the PCB already has had the hole enlarged in an effort to fit the UTM. But I'm glad that it was not too hard to accommodate. Congrats on a successful build!

 

[Volume11]

View attachment 136353

The knobs will be replaced, this was just what I had in my drawers. Two things I encountered on final assembly:

1. To accommodate the output transformer (UTM3524) I had to sand lightly on the PCB since the transformer wouldn't properly sit in the hole.
2. One bracket had too big holes to hold the transformer screws; they just went through. Solved it by further counter sink the holes and then use a small washer so that the screw didn't go through. It means however that the screws sits just a tad proud but it seems to work fine.

AWESOME project! Had a blast building these. Now I'm gonna make myself familiar with them

I had the same issues. I filed the hole for the transformers, it didn’t take much. As for the screws, I just used one of the m2 washers on them before inserting them into the L bracket, then cranked it down a little to make it sit flush.

 

[slipperyflax]

I didn't have the guts to crank down so hard, but I did use exactly the same solutions as you did @Volume11 Perhaps I'll go back and do that! Thanks!
It wasn't big issues at all, just thought I'd share them if there was someone later on that became unsure!
@JMan Perhaps it could be explained by the same reasons in manufacturing as for the difference in sizes regarding the input transformers? But as Volume11 said, it just tok a few strokes with a file and it was all fine and dandy!

 

[slipperyflax]

Been listening to these units on the mixbus now for a while, on different mixes. Some made by me, and some made by others. I don't have much experience with EQs like these since before, but I must say I'm very impressed with how they perform! WOW! Simple but extremely effective. On one mix it was like pulling the blanket off; removing the clouds and let the sunshine through. On another mix, that was pretty scooped, it was so easy to add in the high mids again. Instant bettermakers!!

It's been quite some time since I became this impressed with gear. Maybe my expectations were too low but I'd rather have it that way than the other way around.

Again, thanks to all those brilliant people out there that made this project accessible! You are all aces in my book!

 

[Volume11]

Been listening to these units on the mixbus now for a while, on different mixes. Some made by me, and some made by others. I don't have much experience with EQs like these since before, but I must say I'm very impressed with how they perform! WOW! Simple but extremely effective. On one mix it was like pulling the blanket off; removing the clouds and let the sunshine through. On another mix, that was pretty scooped, it was so easy to add in the mids again. Instant bettermakers!!

It's been quite some time since I became this impressed with gear. Maybe my expectations were too low but I'd rather have it that way than the other way around.

Again, thanks to all those brilliant people out there that made this project accessible! You are all aces in my book!

Seriously, I also would like to thank everyone involved with this project, you guys are awesome. I was playing around with these on a live recording that I did years ago. It brought the vocals to the top of the mix and added a little mojo to them. I’m very impressed so far, to say the least. Thank you