Help! Neovibe build problem Voltages and details inside.

[albatross]

Hi, I posted about this in an already solved thread, but not in detail ... so im reposting to get some attention

I built the neovibe last night, I have it all in the box except for it is not vibing at all
The lamp blinks, and with the trimpot I can adjust the brightness OK, and the rate and depth and volume pots correctly function, except for no vibe.

Also the chorus vibrato switch seems to turn off the signal in one position


I have the ldrs, bridge rectifier, 78l15 , q13 and the lamp socketed

only thing different on this build is 50KA depth pot instead of 50KB which wouldnt make the thing not work?
Im also using 2 1000uF caps rated at 25 volts , as I dont have any higher rated caps which could be a problem.


I am using a EH 24vDC Transformer which is positive tip, so i wired it correctly to the Boss style power jack.

I need some help from someone more experienced with the circuit who could tell me what the volatges below mean, and what could be causing the thing not to vibe. 

would someone be kind enough to look?

I suspect q11 - q13 to be wrong..

All measured below on a 20v scale on a DMM except for the collectors on q11 to q13

-1
q1

c 2.01
b 1.42
e 1.02

q2
c 4.38
b 1.99
e 1.55

q3
c 11.32
b 4.37
e 3.76

q4

c 15.15
b 4.86
e 4.46

q5

c 11.28
b 4.45
e 3.82

q6

c 15.16
b 4.84
e 4.41

q7

11.41
4.42
3.76

q8

15.16
4.78
4.32

q9

c 11.45
b 4.32
e 3.67

q10

c 15.16
b 6.29
e 5.76

q11
c 27.7
b fluctuates between 12 and 14 v
e fluctuates between 14 and 16 volts

q12
c 27.7
b 15-16v
e 15 v

q13

c 22.7
b 5.03 - 5.68
e 4-5 volts

q14 78l15

in 27.7
gnd 0
out 15.1

Also am I right in thinking the square pad is the + rail on the electrolytics? and they all orientate face + down?


Thank you any help at all appreciated!

[R.G.]

The lamp blinks, and with the trimpot I can adjust the brightness OK, and the rate and depth and volume pots correctly function,

That means that transistors Q11 - Q13 are working fine.

Also the chorus vibrato switch seems to turn off the signal in one position

Since that switch normally cuts off the phase-line signal in one position (vibrato) it's possible that no signal is getting through your phase line.

There are no obvious wrong voltages on your transistors, so the individual stages are OK.

What it sounds like is that the signal is being lost somewhere in the phase line. It's audio probe time. Check the emitters of Q5, 7, 9 and 10 for signal. There's a problem between the last place you heard signal, and the first place you didn't.

A soldering open in the path into/out of the LDRs could do this, as well as some others. Find out where the signal gets lost and then write back.

Also am I right in thinking the square pad is the + rail on the electrolytics? and they all orientate face + down?

Yeah. I laid out that board and that's one of the things I like to do to make assembly easier.

[albatross]

Thank you very much for taking the time to reply, you god you!

I actually just triple checked the board and reflowed some traces and now it vibes!

Time to tweak it!


seems much more defined than the easyvibe.

Cheers, ill post some sound clips once tweaked.

BTW, the vibe/chorus switch is fine now too..

[albatross]

Hi,

Heres a few clips playing the usual tunes heard when testing a vibe!

Excuse the playing, only learned them the otherday, I used a software amp&cabsim.
I used a drumloop repeating over ..

Bridge of sighs into BSIAB2 then Guitarrig for Plexi&Cabsim - Vibrato mode
http://www.rogepost.com/n/0492054513
Breathe into guitarrig for amp&cabsim- Chorus Mode
http://www.rogepost.com/n/3545038355
Breathe - Vibrato Mode
http://www.rogepost.com/n/6160413397


I used the LDR's from Banzai, 16-33k ON 500K off and a 20ma 12v lamp, all resistors were 1% metal film.
I always thought the off value should be in the 20M range for univibe pedals though?

I adjusted the trimpot (used a 500R) at described over at geo, for the dim orange/yellow glow at lowest amplitube .

Etched the board no problems, but drilling the pads required a smaller than 1mil drill bit, i think mine was about 0.65.
Had a few problems but all seems well now! I do find the chorus mode a little weak though.


It is definately a little more vocal than the easy vibe, as someone else stated, i see what they meant, worth the day it took to build!

Getting hold of the dual gang reverse pot was a nightmare though.. and a suitale transformer proved costly, but i needed one anyway.

a pic

[axg20202]

Nice one albatross - glad it worked out for you. I also finished my neovibe build last night, including etched enclosure. Hopefully I'll post some pics and sound clips of mine too.

Did you use the film cannister method for the light shield? The reason I ask is that there is a lot of scope for LDR position adjustment with this method (while most people seem to mount the LDRs facing up and flush to the board using the metal box shield method). You don't give any details on the settings you recorded the clips with - they are pretty sensitive controls I find - but one thing I did notice was that the vibey effect could be made to sound a lot less like a tremolo if you fiddle with the LDR position. Placing them a bit further away from the bulb and angled up slightly improved the vibeyness in my build and made the throbbing more gradual and swirley.

As for other tweaks, I can recommend the increased speed mod (change R42 and R43 from 4.7k to 2.4k or 2.2k) and the depth mod (R49 from 4.7k to 47k)

Andy.

[alderbody]

Placing them a bit further away from the bulb and angled up slightly improved the vibeyness in my build and made the throbbing more gradual and swirley

I could double that. 

I must have done the same thing long ago and i believe i never went back.

[albatross]

Thanks for the tip!, i have them almost pointing up, and it sounds more vocal now I reckon.

In the soundclips above, the depth and vol were maxed, and rate was around 60% i think.

Heres another soundclip straight into the pc, no amp or cabsim, showing the vibe with depth and vol maxed, rate at 50 % then 75% then 100% for vibe mode, then same for chorus

Cheaper than chips strat copy / switch at 4th position down> vibe > pc soundcard:

http://www.rogepost.com/n/7221638228

Does that sound OK ?

[axg20202]

Sounds good to me. Personally, I prefer the slower speeds with depth not set too high i.e. clearly audible vibe without it dominating. With a tubescreamer in front of my neovibe, I couldn't put my axe down last night through constant noodling. I also went two steps further and tried a tubescreamer in front, another tubescreamer to follow, all followed by my RAT - now that WAS fun! I think driving the neovibe with a bit of sensibly set OD (nothing too hellish) really brings out the tone of the vibe, with fairly conservative settings on the vibe sounding best to my ears. There are some other posts where RG I think explains what's happening when you put distortion in front vs. behind the vibe. Definitely a broad range of sounds available depending on where the vibe is in your chain.

Next on my list - a control pedal for the neovibe. I just need to find a wah enclosure from somewhere.

Happy vibe-ing!

Andy.

[SteveB]

Sounds good, but I think your Vibrato/Chorus switch is wired backwards. The "vibrato" clips sound more like "chorus", & the "chorus" more like "vibrato".

Any volume differences between the 2 modes?

Steve

[axg20202]

As for other tweaks, I can recommend the increased speed mod (change R42 and R43 from 4.7k to 2.4k or 2.2k) and the depth mod (R49 from 4.7k to 47k)

FWIW, I just tried changing R49 to 10k (based on another neovibe post) and I prefer it. The difference is subtle but the effect is a little more prominent. I found the stock 4.7k to be a bit too abrubt in swing and the 47k a touch too tame.

[albatross]

Sounds good, but I think your Vibrato/Chorus switch is wired backwards. The "vibrato" clips sound more like "chorus", & the "chorus" more like "vibrato".

Any volume differences between the 2 modes?

Steve

Hi i think you are probbaly right, the switch aint wired up wrong, i just perceive vibe to be the trower sound, whoich is actually chorus mode? there isnt actually a volume drop, the vibe just is different & a lot weaker at slow speeds but more prominent at high speeds.

As for other tweaks, I can recommend the increased speed mod (change R42 and R43 from 4.7k to 2.4k or 2.2k) and the depth mod (R49 from 4.7k to 47k) I also changed the 68ohm res to 120ohm

FWIW, I just tried changing R49 to 10k (based on another neovibe post) and I prefer it. The difference is subtle but the effect is a little more prominent. I found the stock 4.7k to be a bit too abrubt in swing and the 47k a touch too tame.

I have done the speed mod, thanks it has made a huge difference now! the 10K depth mod i have hooked up to a DPDT switch and it dosent do anything to my ears, Ill have to try the 47K instead. The spoeed mod is definately worth doing , I used 2.2k resistors

Heres another clip of bridge of sighs with the tweaked vibe into a BSIAB2, i dropped the tuning down 2 steps..
short clip:
http://www.rogepost.com/n/4022140824

PS: anyone know a decent tab to all the fills on this great song?

[nico13]

Hi Albatross,

It may be a stupide question but how to download your clips?

[albatross]

hi there, they have gone now, rogue post only holds files for 100 days I think.

Im quite tired and its late now, maybe tommorow if i can ill post a clip or 2

[nico13]

OK Albatross,

Thanks