MXR - six band graphic eq

[dellamorte]

anyone have one ?
i have been looking for one for ages. just missed out on one on ebay too

[soulsonic]

I HAVE ONE!

I just found it recently too - been lost for years in storage!

Anyway, I'll definitely trace this one for you since I've not seen a schematic of it anywhere. The one I have is an early 90's model, but I think it's the same as the older one - the board design and components look true to the old MXR style.

[dellamorte]

here is a pic of an older one if it helps

[soulsonic]

The board on mine is slightly different: it says, "109-3001-104" across the top. Other than that the layout looks identical with similar style components. Too bad that pic doesn't show the other side; it's a two-sided board. I'll get the pics of mine up soon and get it traced; it looks like a straightforward simple EQ circuit. It would be a good DIY project.

[borislavgajic]

it looks like a straightforward simple EQ circuit. It would be a good DIY project

nice nice nice

[soulsonic]

Here are gut shots:



I will try to make time to trace it during this week.

[dellamorte]

the wire side pic doesn't seem to be loading properly , not sure if it is just for me or what.

[rs]

Your right, i can't see it too!!

[soulsonic]

Try refreshing now and see if it shows up. I was having issues with the FTP thing yesterday when I was uploading that stuff. Sorry, it should be okay now, I've re-uploaded it.

[dellamorte]

all fixed! thanks
now the fun begins!

[Krinkle]

First post for me, spent the last 2 days browsing the site. Best one I've seen in a LONG time!

I'm very interested in building a clone of the blue 109, are you still going to do a schematic?

Darrin

[Redhouse]

I've got one of these somewhere down in my basement, I'll have to go have a look 'round for it.

[eleanor296]

more pics!!!!
Please!

[Redhouse]

Until this thread, I forgot I even had this 'ol thing, mine's a block-logo:
(it doesn't say "Wire Side" on the back)

[eleanor296]

Hey Redhouse,
could you give us the values of the poly caps that we can't see the markings on?
It'd be very appreciated

...Or just sell yours to me

~Andy

[BJF]

Hi,

I had one of those and it was noisy as a waterfall.
It is possible to replace all the gyrators with lownoise transistors and I did that with half sets NPN and half sets PNP's so the emitter load could be wired low enough mechanically as each buffer then would need one extra resistor. This replacement reduces not only total noise but also noise from boosting just one band.
I also replaced the EQ amp with an NE5532 and total noise was cut down to a level where the unit actually became useful at stagelevels.




This takes time to do and the pcb lines are delicate but is well worth it I'd say.

Have fun
BJ

[O.B.Y]

would you like to share that layout or scematics?