Reddish 500 EQ

[Forcemusicgroup]

Anyone care to post some sound samples.

 

[JMan]

My prototype is on loan to studio here in Chicago, so I can't do sound samples currently. If you would be willing to create some when your unit is finished, it would be a welcome contribution!

 

[slipperyflax]

While waiting for the UTM order I couldn't help myself.. So I testfitted the PCB on the metalwork from Kevin (just soldered one pin on components that could effect alignment on the front panel) and now I wonder if anyone else noticed that this step is impossible:



When I'm placing the toothed washers between the switches and the L-bracket I can't fit the PCB on the mounting screws. It's just too tight. When removing the washers I do have a good fit. Since the step in the build guide says it's non-optional I thought I'd throw the question out there..

 

[JMan]

I am not sure why that would be, but go ahead and try it without the washers. Bear in mind that I designed everything here with the metalwork from Frank, and although Kevin got the same files from me, he did make some small tweaks. His version ended up coming with a powder coat finish, right? Maybe that is what is affecting that spacing.

Regardless, try it without the washers, but pay very close attention when you tighten the nuts on the switches when mounting the front panel. If there is any gap between the switch body and the L bracket, you will want to add something (maybe a flat washer) so that you aren't cranking on the Grayhills and stressing their pins. But if it's a perfect fit, hey, that's even better! Please report back.

 

[slipperyflax]

I was thinking maybe the powder coat was the difference to but I feel it shouldn't add as much thickness as the spacer would but.. Thank you for the pointers!

 

[thelivingroom]

I was thinking maybe the powder coat was the difference to but I feel it shouldn't add as much thickness as the spacer would but.. Thank you for the pointers!

Unless they really caked it on, the powder coat only adds about .25mm maximum total (total = front and back), but usually is closer to only .10-.15mm, based on what I’ve measured out of curiosity that I’ve gotten from Frank, SendCutSend, and Front Panel Express. If it’s close you could maybe use a small round file to elongate the PCB hole a little bit. I have a set of small hobby files that I keep in my kit for any fudging I may need to do.

 

[JMan]

I agree that the powder coat shouldn't add much, but the only other thing I can think of is that perhaps the bend on the L bracket is a little tighter on Kevin's metalwork (not a bad thing at all).

My thought is that if it fits snugly without the toothed washer, it's as simple as leaving out the toothed washer. There wouldn't be any problem with that. I had things laid out so that the washer was working as a spacer, which was needed when using the metalwork that I had Frank fabricate, but if it's not needed on Kevin's bracket, it can just be left out. If, on the other hand, a small spacer is required (more than nothing, less than the toothed washer), a simple flat washer or two of appropriate thickness would be my choice. Again, the only goal here is to make sure everything is snug and that there is no additional stress being applied to the solder joints on the switches when fastening the front panel.

 

[lukas]

Few measurements.

 

[JMan]

Wow! I know you wound your own inductors. Did you also wind the input and output transformers yourself?

 

[lukas]

Yup.

 

[slipperyflax]

[...] Please report back.

Well, I soldered switches and everything tonight and tried the fit of it all and in my case it fits like a gloves without the toothed washer. Sorry for bad quality pics but I cheaped out when buying my latest phone



(I have not forgotten about R0, promise!)

 

[thelivingroom]

Well, I soldered switches and everything tonight and tried the fit of it all and in my case it fits like a gloves without the toothed washer. Sorry for bad quality pics but I cheaped out when buying my latest phone

View attachment 135512View attachment 135513View attachment 135514

(I have not forgotten about R0, promise!)

Nice! Looks great!

 

[JMan]

Outstanding!

I've uploaded V1.1 of the build guide to the first post. It includes a brief note reflecting @slipperyflax 's finding and the inclusion (or not) of these washers as well as an addendum to help match leads when using either of the UTM output transformers.

 

[Volume11]

Oh, it sounds like the 3524 has different lead colors than the custom-wound 3523LP that was being ordered previously. That is good to know, I'll need to update the build docs with that info. Do you happen to have a data sheet? When I was writing the build guide, they hadn't published anything for the 3524 yet.

It sounds, from what you wrote, that it should be as follows, but if we can drum up a data sheet it would be good to confirm.

PCB: Yellow Red Orange Brown
3524: orange black yellow red

I received UTM3523LP transformers from the group buy. I'm checking the docs, and its not helping me much. Do I need to tie a couple of these leads together? The Grayhill mod worked great, and was very easy, thanks for the heads up on that.

 

[JMan]

@Volume11 The version of the build guide that is currently attached to the first post includes an addendum all the way at the end with a table for how to match the UTM lead colors. It should be pretty straightforward once you're looking at that. For the 3523LP, you do need to tie two of the leads together - from memory, I want to say it was black and blue, but definitely refer to that table I mentioned to confirm.

 

[Volume11]

I see it now, thank you!

 

[Volume11]

I also wanted to mention that you can spread R5 and R10 enough to use a Bourns 3266-size trimmer for R0 if you’d like. I had one in the wrong value that I used as a gauge. I’m going to use a 5k pre-trimmed to 2.4k to start.

View attachment 133968

Do you just snip off the middle lead for this?

 

[thelivingroom]

Do you just snip off the middle lead for this?

No, I bend Pin 2 (center pin) over to Pin 3, flat to the bottom of the trimmer, bend 1 and 3 to fit the resistor footprint, tack 2 to 3 with a little solder, pre-trim it to the value of the resistor it’s replacing, then insert it and solder it to the PCB, same as you do for the resistors.

 

[Volume11]

Awesome, I added one to my order to try it out. Thank you

 

[thelivingroom]

Awesome, I added one to my order to try it out. Thank you

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