MXR 10 Band Equalizer: Dim LED Mod M108S

[@BAND-MAID-USA]

When I first turned mine on I was playing outdoors. I had 2 United, 1 Delta, 3 JetBlue planes land and a UFO flew by also. They all deplaned and actually watched my band play. Without this pedal, we wouldn’t have had an audience.

[@robertw1871]

Thanks bud, saved me a bunch of time tracing the circuits out…. Thing was killing my eyes, no idea what MRX was thinking on this, the brightness is totally insane….

[@Bassguitarist1985]

I know right?! Crazy!

[@robertw1871]

@@Bassguitarist1985 Ended up with 39k, have a whole kit of 1%, figured that was a value I’d never use for anything else… Got it back on the pedal board and it looks totally normal, which is amazing lol… So much happier with it now, and I don’t have to flip the thing over to live with it… Thanks again…

[@originalaldente]

Thanks a lot for the tutorial! I just changed the 3 resistors to 33kohm. It works perfectly. Now it shouldn't be a problem to use the ten band eq in a pretty dark venue. I really didn't like the blinding white LEDs. Thank you very much!

[@Bassguitarist1985]

They come with white LEDs now?

[@VictorHenskens-j9d]

Thank you very much! My local e-workshop did the modification and it works great. Now I'm able to see the rest of my pedal board :) I gonna change the 2 outer LED's for a different colour as well.

[@stoatystoat174]

An alternative is changing the LEDs LED; rectangular; 2x3x4mm; red; 330÷450mcd; 100°; Front: flat; 20mA Manufacturer part number: OSR5RU7BA1B (these are red but it gives you the other specs) That way you can pull out the old ones with pliers. Cut the legs of the new ones to the same length and slot them in. I'm in no way having a go at this video though, he had the skills, tools and resistors to do it and kept the MXR blue colour. Also shown where the relivent resistors are. Plus skills transferabe to anything with a troubling LEDs. You could even swap the resistors for trim pots so you could set the level exactly where you want it. Love these educational videos that make the internet an awesome library. 🤖❤

[@originalaldente]

I already tried changing the LEDs to other mcd-specs. It didn't work that well with the red ones (~450mcd), since it was still to bright. Though I only have basic soldering skills in trough hole technology (THT), it was not that complicated to solder this tiny little SMD 0805 resistors. You just need lots and lots of Flux for it. And yeah, I don't have the best eyes at all...I saw just enough. Conclusion: Don't be afraid of that funny work ;)

[@boomtap7554]

That was super-helpful. Thanks for making the video. Thanks for mentioning Chip Quick. It worked well for me.

[@jcondon1]

Much better

[@Bassguitarist1985]

Thank you! Agreed!

[@Bassguitarist1985]

Thank you for watching! Hope all is well!

[@joeylizotte7537]

Is there a way to change the frequencies of the eq (i.e. changing the 1k to 1.2k)?

[@Bassguitarist1985]

Yes, you would need to change the values of R23, C13 and C14. This is based on an older schematic version E instead of G. There are calculations that you can do to figure out those values I haven't really dug much into that. If you pose your question on the DIY stomp box forums (i forget the link) I'm sure you can find some resident smart people to help with that modification. It is definitely doable but with the right tools.

[@joeylizotte7537]

@@Bassguitarist1985 Awesome. Thanks!

[@cevikmetalcovers]

@@Bassguitarist1985 Is it also possible to change all 10 frequencies to a specific range (2k to 4k) ?

[@Bassguitarist1985]

@@cevikmetalcovers yes but like above you need to calculate the resistor/capacitor values to change the fader frequency operation. Its a heavy mod

[@sonysoni5079]

Hi. Great video, thank you. I have one question, I want to by this, or MXR 6 band EQ, would you say, is this completely analog EQ, that absolutely wont induce any latency? Even that new noise reduction circuit that they mention in advertising? Sorry on my bad English.

[@Bassguitarist1985]

@@sonysoni5079 yes, all analog. There is no latency or A/D/A conversion inside the pedal.

[@sonysoni5079]

@@Bassguitarist1985 Thank you so much for your time. You've been very helpful !

[@cosmiceon]

Hi thank you. What size smd resistors are these? I know they come in different form factor or footprints. Thank you

[@Bassguitarist1985]

0805 package size. Details in description.

[@andre257]

Hey bro, great video. Thanks, very informative.

[@vanholben]

Hi, what would cause my 2 sets of inner lights to not turn on at all?

[@Bassguitarist1985]

Bad resistor or LED. The banks of 5 are in series. I'd lean towards a bad LED, or one or more can be reversed in the socket blocking the current in circuit

[@vanholben]

Thank you!

[@steveojamo1826]

i thought i read that if you’re running 9volts instead of the 18 the inner lights don’t light up.

[@BrianPellerin]

What a great idea! I’m in a house of blue lights and it hurts 😅

[@Bassguitarist1985]

yeah they can cause eye damage over time im sure!

[@psychotogether5114]

Anyone know about noise issues with the leds on the black version?

[@Bassguitarist1985]

I'm not aware of any noise issue with the older black version. When you say noise, does it sound like a fizziness or an audible distortion?

[@psychotogether5114]

@@Bassguitarist1985 yeah pedal is on and definite fizziness. Pulled leds and no difference. Had to shelve it. Got the donner $50 eq and it’s great.

[@Bassguitarist1985]

@psychotogether5114 I just ran into this exact issue on the MXR silver M108S. The two outer LEDs are the clip LEDs. They blink when you are pushing too much signal into the pedal or if it's outputting too much signal. The LEDs need to be the standard blue LEDs and the original 2.2 k ohm 1206 size R46 resistor installed. The clipping circuit is tied to the negative bias voltage for the internal op amps. Changing R46 or the LEDs will change the bias of the op amps causing the fizziness. I never realized this until I really started digging into the schematic which has changed over some of the revisions. There are some revisions that do not have this issue and some that do. Hopefully that gives you some perspective.

[@psychotogether5114]

@@Bassguitarist1985 thanks! Will check out. It’s too bad that pedal has issues. It’s built like a tank!

[@Bassguitarist1985]

@psychotogether5114 yeah it just means that it's harder to modify the pedal to have dimmer LEDs. The next best thing would be to take out each translucent LED lightly sand them with 3,000 grit and then color them with the permanent marker to dim them that way.

[@AA_MusicGuy1111]

Do the vol and gain faders also dim? Hard to tell from video

[@Bassguitarist1985]

Yes they do. There is a separate 2K resistor that would need to be replaced for the volume and gain. There are two more 2K resistors that control the first five faders and the last five faders. Changed it to a higher value to dim the LEDs so they are not blaring me in the face

[@AA_MusicGuy1111]

Thanks would you happen to know which resistors those are? @@Bassguitarist1985

[@Bassguitarist1985]

​@@AA_MusicGuy1111 R13, R37, and R46

[@AA_MusicGuy1111]

Thank you so much@@Bassguitarist1985

[@jde1780]

I went with changing over to red LED's and also changing the resistors to 33K. I could have gone lower with the resistors to a 27K. I'll leave the resistors at 33K for now. Originally with the blue LED's, I started with the highest resistance to keep the LED's lit (~45K). The biggest thing is using red LED's. Red preserves your night vision better and does not burn out your sight as easily as the other colors. The worst thing is finding a source of LED's. they are difficult to find and are expensive. Thanks for the Vid.

[@Bassguitarist1985]

Hello and thank you for watching! Yes I went with a 33K as well. I did just modify another customer's MXR with 47k but now he is hearing a fizziness artifact in the audio signal. I'm wondering if that has something to do with the clipping LEDs on the outer faders since the LEDs are connected to the bias supply in order for them to work in that capacity. I haven't had that issue with the 33k so maybe I need to change out his 47ks for 33K or even 27 since the difference in brightness is going to be negligible. The LED size you need are 2x3x4 mm and square. I got a bunch of them that are transparent and frosted in RGBYW. The problem with LEDs especially in this form factor is the " MCD " rating which refers to brightness. The goal is to find something under $500 otherwise it's just going to be crazy bright no matter what. I've also thought of building a three gang multi-turn potentiometer where the brightness can be adjusted for all of the LEDs independently but then that would require drilling the base plate to get access to these which I wasn't really too wild about but it's more of a set it and forget it type of thing anyway. Anyways thank you for your information and sharing it and for watching the channel. Cheers

[@stevebotos6138]

Great video! Did you consider installing three potentiometers using wire leads in lieu of the board mounted chips, possibly with a minimum size resister wired in series with it? The series resister would only be to ensure that the LEDs aren't over-driven.

[@Bassguitarist1985]

I did yes, and its doable, but seemed unnecessary to have a variable brightness feature.

[@killboxone]

@@Bassguitarist1985 I think the value and need would be if/when you play outdoor venues in the daylight vs inside a dark club. Nice to have a variable slider for the brightness. Great video and thanks for sharing the knowledge. 🤘

[@Bassguitarist1985]

@@killboxone true on the variable slider/potentiometer, it would need to be a 3 gang pot, and that can get large in physical size to fit inside the pedal. The only other solution is 3 small trimmer pots to do each circuit.

[@jhford]

@@Bassguitarist1985 or you could possibly drive all the LEDs with a single pot and run the wire to the relevant contact pads

[@Bassguitarist1985]

@@jhford no there are three separate resistors thus three separate circuits for the LEDs. One resistor runs the volume and gain, and the other two resistors run the first and second vank of five faders. If you want to have the operation you suggest it would need to be a three gang trim pot and I don't know if they make them that small

[@jammer777]

Too bad MXR doesn’t just change these from the factory with all the complaints of the brightness.

[@Bassguitarist1985]

Agreed, that or put a dimmer pot you can access from the outside. No need to light up an air strip with it!

[@vic12551]

Excellent info. Can you show how I did it?😊

[@Bassguitarist1985]

I explained the process. Sorry i was not able to show all the detail.

[@williamolynnger9143]

Mine has seared an image of Jesus on my ceiling. I need to do this!

[@hydorah]

MXR still haven't learned the silver one with blue LEDs is still insanely bright

[@Bassguitarist1985]

@@hydorah absolutely. Really happy with the mod. I don't need to light up an airport landing strip with these LEDs.

[@CustomTele52RI]

Nice, but the hot tweezers cost $130 - seems far simpler and cheaper to just replace the LEDs, which you can pull out with your fingernails. I think I'll get dim red ones.

[@Bassguitarist1985]

As long as you were able to find the right size LED with the proper specs. I have the tools so I didn't bother looking for alternative LEDs

[@realtruenorth]

How does this compare to the whirwind perfecr 10 pedal? Anyone compare sound quality?

[@Bassguitarist1985]

I don't have any experience with the whirlwind pedal hopefully others will chime in. If it's based on the same quad channel op amp then I would expect similar performance

[@realtruenorth]

@@Bassguitarist1985 how would you sound quality and noise floor of the MXR?

[@Bassguitarist1985]

@@realtruenorth sound qualities transparent and the noise floor is low until you start to boost the higher frequencies which is expected. It's the tool you never thought you needed but do!

[@realtruenorth]

@@Bassguitarist1985 yeah, I'm just trying to figure out between this, Empress parametric EQ pedal and the whirlwind perfect 10, im sure they are all good.

[@Bassguitarist1985]

@@realtruenorth yeah you really can't go wrong with any of those. Also the Caline CP-81 is an exact clone of the MXR M108S

[@jinxarchives]

Can’t get the back off mine

[@Bassguitarist1985]

Gentle persuasion with a rubber tipped hammer?

[@BAND-MAID-USA]

Throw it up against a sturdy wall until it falls off.

[@Firstinversion899]

Nice!

[@GuitarUnderground]

Just run it at 9v and it won't power the LEDs...

[@Bassguitarist1985]

Then you lose the headroom you get at 18V. 9v is not the solution.

[@GuitarUnderground]

@@Bassguitarist1985 It might not work for your needs, but it is a very simple solution for a very simple problem. The next solution is buy a different EQ. Modifying the pedal seems to me like a pretty over-engineered solution for such a fairly cheap pedal.

[@Bassguitarist1985]

@@GuitarUnderground hey whatever works. I use 18 volt active bass pickups so the headroom is important to me. Thank you for watching!!

[@skeymoson]

Awe hell no … I’m pretty sure I can come up with a low tech solution

[@Bassguitarist1985]

@@skeymoson I hear nail polish works great!

[@skeymoson]

Ha Maybe !! But honestly yer video is pretty impressive . Thanks for the tips … I can’t help but wonder why they haven’t addressed this obvious problem .

[@bagoftoysmusic]

You've read my mind. These LEDs suck.

[@Bassguitarist1985]

But they can be dimmed. You could also replace them with a different color too like green