Just wired her up, some thoughts, i.e. EQ section, two way speaker.

Submitted by ryugreen on Sat, 06/02/2012 - 13:59

Hey all, just finished wiring up my Stella. Took a few hours longer than it should doing some poor soldering technique I'm still working on. Filled a few PCB holes accidentally and it was hell getting the leads in there once that happened. Even partially melted the PCB around the LED a tad but was able to build a solder bridge of sorts and it works now.

Anyway, I've got her hooked up now to a 6.5" two way I salveaged from a cheap outdoor speaker. I'm thinking I should disconnect the tweeter. As it is now, it is very very trebly and I feel like to tweeter is eating up most of the power and not leaving a whole lot for the woofer. Maybe it doesn't work that way, but I would like to hear some more low-mid. Anybody else running a two-way?

My second thought, could the hack section be used to input an EQ? i have seen some EQ kits on other sites and I think it would be great to somehow install one of these on the Stella.

If not at hacks, where could the output of the EQ be inserted? Could a little wire to the right resistor do the trick?

Anybody done this yet?

Ryan

Member for

11 years 5 months

John

Sat, 06/02/2012 - 18:20

I'm glad you got it working!

Petey Twofinger did a Stella Amp build with a two way speaker, and he posted about it here:

http://www.crazybutable.com/forum/topic30-0

If you have any questions about how he wired the kill switch for his tweeter, you can post them in this thread, I'll tell him to check this thread for questions.

The "hack" is really for output only, like a headphone output or a line out. If you want to put an EQ or tone control circuit in, you have to decide where you want it. Obviously you can put it before the entire amplifier if you want, but that won't help with the harshness if you overdrive the Stella front end. Probably the best place to do it is just before the final amp stage.

Take a look at your Level pot, and look at where the pot connects to the board. On the board, there are three pins, 1, 2, and 3. You want to cut the middle wire, the one that connects to pin 2. You can either separate the three wires from each other and only cut the middle one, or you can cut all three and re-solder wire 1 and wire 3.

The wire coming off your pot is the signal coming from the guitar. The wire leading to the board is going to the final amplifier stage. You put the wire coming from the pot to the input of your EQ circuit and you put the output of the EQ circuit to the wire that leads to the board.

Now, before you do any cutting or soldering, look at your EQ circuit. What kind of voltage does it need to work? Is it a passive tone circuit that you lifted from a guitar pedal? Then you can probably just drop it in. Is it a big chunk that you ripped out of another amp, with its own input and output and power supply voltage? Then it's going to be a little trickier, you need to make sure that the input voltage range it expects is compatible with what the Stella Amp front end puts out. (The front end of the Stella Amp can put out almost the full supply voltage peak to peak, so if you are running your Stella at 6 volts, then the final signal will range from 3 to -3 volts, 6 volts peak to peak. If your EQ is expecting 1 or 2 volts peak to peak, then you will seriously distort your input.)

petey (not verified)

Mon, 06/04/2012 - 16:15

that mod was just installing a kill switch to the tweeter . the tweeter is wired off the binding posts , actually the main connections of the speaker , so i cut the switch in going thru the black wire that feeds the tweeter , to turn the tweeter on or off . its nice to have , like if i am not using a pedal , and its clean the tweeter sounds very nice , with a fuzz or distortion , shutting the switch / tweeter off can reduce the ice pick / chainsaw effect quite a bit . this may or may not give you the flexibility you desire though . i would suggest installing a switchable tone capacitor . i believe this would be c9 , correct me if i am wrong please , John . anyway you would remove c9 from the board , then get an additional capacitor of a larger value , experiment to find what you like . at this point you would solder the original cap and the new treble cutting cap of a higher value to a dpdt switch . one on each side , with 2 wires in the middle feeding back to the board . if you get an "on off on:" variety of switch , the off position in the middel , this would produce an undesired effect so i would look for an "on - on" variety dpdt or just do not set that switch to off ... and deal with it . here is a pic :

http://www.fuzzface.es/mods/ValveCaster_MIC2.jpg

i spose either way would work , and that second switch on the right may be a bit cheaper ...

also i am not 100 percent sure about this being the right cap for the mod ... like c9 , it may be c11 or something but ... or you could just experiment with adding a cap at the input or output stage say right before the volume pot ... adding a cap at the input , well that is what is inside your guitars tone control is just a cap so , its pretty much a no harm done deal , messing with it .

good luck .

Member for

10 years 6 months

ryugreen

Thu, 06/07/2012 - 17:58

I like the idea of the switchable tweeter.

ALso the cap idea. Had no idea it would be that easy. So could one wire up a potentiometer to this cap to allow some kind of degree of rolling the brightness in or out?

Member for

11 years 5 months

John

Fri, 06/08/2012 - 07:14

You know, I tried doing a tone cutting cap mod before with C9, and I ran into some problem or another and it never worked. I feel like I had to be doing something wrong, like maybe I had a solder bridge in the wrong spot or something, but I couldn't figure it out. Then we moved and I packed my hacked board into a box and I haven't seen it since.

Anyway, Petey is right, replacing C9 with a higher value cap should cut the tone quite a bit. It did when I was testing everything out on a breadboard. Let me know if you get something working!