ElectroVibe Modifications Thread
- Thread starter Big Monk
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Big Monk
Well-known member
I don’t remember honestly. I’ll have to experiment with various LEDs.
andare
Well-known member
Very nice!
Even though I doubt I'll ever adjust the speed while playing, I still want a visual cue as to which Speed knob is active so I will do the bi-color LED mod. It would be just perfect if this LED could also blink with the rate!
BTW maybe I missed it but I don't think the Darlington mod has been explained other than "it drives the output better".
As a newbie I barely know what a Darlington is (a pair of transistors mashed together in one package?) let alone understand what it does to this circuit.
As for subbing in 10uF caps, does the Electrovibe sound thin without them? I'd rather avoid soldering, desoldering and soldering again several components if it ends up sounding thin or boomy. That's a surefire way for me to ruin a PCB
The Gator
Well-known member
Honestly do not know the answer to that Andare. Normally, I either bread board a circuit first to try mods, or put sockets in the board where i want to try different values.
I wasn't about to bread board the electrovibe. I just made a choice that I like a bit more of a phaser sound. To me it seemed getting the second notch larger but still sound like a univibe was the place to start.
As far as the transistor mods go, Big Monk is right. Probably not necessary. Makes no audible difference. I just have a lot of parts I have collected over the years. So I did the mods.
If you want a bicolor speed LED that is a rate LED as well, then you are going to have to wire the speed switch by hand and make some changes. I thought about it, but in the end, I was not feeling that ambitious and liked using the provided switch breakout board a lot. Super easy.
I wasn't about to bread board the electrovibe. I just made a choice that I like a bit more of a phaser sound. To me it seemed getting the second notch larger but still sound like a univibe was the place to start.
As far as the transistor mods go, Big Monk is right. Probably not necessary. Makes no audible difference. I just have a lot of parts I have collected over the years. So I did the mods.
If you want a bicolor speed LED that is a rate LED as well, then you are going to have to wire the speed switch by hand and make some changes. I thought about it, but in the end, I was not feeling that ambitious and liked using the provided switch breakout board a lot. Super easy.
Big Monk
Well-known member
TBH always-on blinking LEDs are annoying
Tie the Rate LED ground to the main bypass switch. That way when you switch off the pedal, the Rate LED turns off as well.
So question for the phase mod on R16/17: what final values are you guys seeing? Are they like a few hundred ohms off of each other or like a few thousand?
Second question: my electrovibe mini has a really strong effect/depth on the vibrato setting, but seems a bit too subtle on the chorus setting. Will the phase mod likely improve this? I've messed with the bias and offset ad nauseam and am pretty sure I have that as dialed in as possible to maximize the depth.
Second question: my electrovibe mini has a really strong effect/depth on the vibrato setting, but seems a bit too subtle on the chorus setting. Will the phase mod likely improve this? I've messed with the bias and offset ad nauseam and am pretty sure I have that as dialed in as possible to maximize the depth.
Big Monk
Well-known member
I’ve never measured. The few I’ve built and sold were tuned by ear with trimmer.
This is the crux of the issue with the original Univibe circuit. Got the “Chorus” dialed in? Vibrato is weak. Got the Vibrato dialed in? “Chorus” is weak.
I’m convinced that they looked at the circuit while designing and just threw the switch in there because, why not?
The Vibrato effect on the Univibe is not that good on its best day so you have to either put the lamp controls up top or just suffer.
Big Monk
Well-known member
Tune the LFO. 100%
You definitely can’t have it both ways, i.e. you can’t have strong vibrato and strong vibe.
The phase mix is like a last 5% type mod.
Gotcha. Like I said I've tried everything with the LFO. Anything else I could possibly be missing? Possibly my expectations are out of line.
Big Monk
Well-known member
You have to tweak the trimmers for a strong vibe sound while using a light shield.
Big Monk
Well-known member
I would do the following:
1.) Set the brightness of the bulb to medium, literally meaning what you deem it’s middle/median brightness
2.) Install your light shield.
3.) Tweak the offset/bias trimmer until you get the desired throb/intensity of effect.
Note: I generally do this with the intensity control maxed.
Hello, i'am tweaking my ElectroVibe build chasing that Throb effect one big difference to original univibe i dont know why they have mistake in both schematic and BOM.... They powering whole signal section trough L75L12 (12V) and it should be by my opinion 15V thats where even schematic is wrong... L78L12 in schem and it shows +15V output from that regulator! So i believe that there should be L78L15.
Next.
I wonder why you use those 2.2uF tantalums ? Wou wont get as much sqeak as bulb is drived ? I thought that tantalums are not much good for audio purposes... https://www.coda-effects.com/2015/04/capacitors-which-one-to-choose.html.
Next.
I wonder why you use those 2.2uF tantalums ? Wou wont get as much sqeak as bulb is drived ? I thought that tantalums are not much good for audio purposes... https://www.coda-effects.com/2015/04/capacitors-which-one-to-choose.html.
Big Monk
Well-known member
There’s not enough of a delta in the supply voltage to properly regulate at 15V using the L78L15. That’s why the L78L12 is used.
Leakage is the issue per my talks with @Chuck D. Bones
You need low/no leakage/residual resistance in the LFO caps for it to work it’s best.
Also, those caps aren’t in the audio path, they are in the LFO.
Yeah, i'm not using LT1054 but step-up module to push 9V 1A in to 18V then trough regulator now 7815 and i noticed biiig improvement in woble. But even that i used L7515 the power consuption is still around 100-120mA. Now i try to swap out those 2n5088 which are probably fake bcs they're all around 650 hfe and original transistors were around 350 hfe.
So if i swap out those for tantalums ill get more silent LFO or whats the deal there ?
Big Monk
Well-known member
For those who have done the unity gain mod and are still wishing for a bit more signal:
1.) The traditional Univibe transistor preamp is in fact a discrete opamp.
2.) It’s overall gain is governed by the classic 1+(Rf/Ri) opamp gain equation.
3.) For either the Big Electrovibe or the Mini, this equation would be as follows:
1+(R2/R5)
Stock gain is ~4.
Here are some values of R2 (3.3k nominal) and their corresponding gain values;
3.9k = 4.25
4.7k = 4.91
5.6k = 5.66
6.2k = 6.16
6.8k = 6.66
7.5k = 7.25
1.) The traditional Univibe transistor preamp is in fact a discrete opamp.
2.) It’s overall gain is governed by the classic 1+(Rf/Ri) opamp gain equation.
3.) For either the Big Electrovibe or the Mini, this equation would be as follows:
1+(R2/R5)
Stock gain is ~4.
Here are some values of R2 (3.3k nominal) and their corresponding gain values;
3.9k = 4.25
4.7k = 4.91
5.6k = 5.66
6.2k = 6.16
6.8k = 6.66
7.5k = 7.25
