Stereo Neovibe Univibe build report

[3/4 North]

Finally finished R.G.'s Neovibe with his stereo and input buffer mods



footswitch 1 - true bypass to lower jack & power cut
footswitch 2 - cancel effect (leaves it as booster/splitter)
footswitch 3 - chorus/vibrato



I added two LPB2 boosters (as suggested in an earlier Neovibe thread) which helped the "tone suck" of the cancel switch and made the volume switch useful.
Also I added a JFET gain boost which cleaned up a lot of noise.
The input buffer didn't seem to help with either of these issues.

Here are the mods to the board




and the daughter boards

JFET biased with 200k trimmer to 4.5v
(I accidentally left off the Mixer 1 input at the lower right corner, between the 200k trimmer and 47k resistor)

The boosters use the volume control.
The lamps had 2watt resistors, but only because I had the voltage regulator in backwards.

Here's what it sounds like - takes a bit to start and the volume is recorded too low ( I'm just learning Sonar)
http://digitalmgi.net/guy/neo.wma
True bypass - booster/splitter - chorus mode - vibrato mode - chorus mode

[ulysses]

that looks awesome dude! congratulations!

where did you buy the jewel lamp covers?

cheers
ulysses

[3/4 North]

Those are from Antique Electronics Supply http://www.tubesandmore.com/ along with the 6.3w bulbs they take.

[Aharon]

One more.....where do you get those standoffs?
Thanks
Aharon

[3/4 North]

standoffs are from Mouser

561-LAD250               Eagle PCB Posts/Guid    ADHESIVE PC SPT 1/4"

[Aharon]

Great,thanks
Aharon

[momo]

Hello, Im just about finished my neovibe build and now Im wondering if I should do this stereo mod, my question would be, is there any loss of signal or quality if I decide to use just one output? Also does the vibe go from one output to the other as in real stereo,or is it just a"wider sound"
thanks and congrats on this awsome build.

[3/4 North]

The two signals are opposite phase, if I were to plug both outputs into the same speaker they would cancel (as I found out). If you tried to run both signals out of one jack they would also cancel, low to no sound.

Do you mean if you had two jacks but only used one? In that case no loss in quality or vibe that I could hear, it would be like a normal uni-vibe.

The vibe sound does bounce from one speaker to the other, especially in chorus mode.

[momo]

Awsome, now I would have to change casing to acomodate the extra....hmmm, well, I just dont know!
anyway very nice build you got there!

[3/4 North]

Thanks,
I'm going to add an expression pedal once smallbear gets them back in stock.
Still has a pop when I turn it on despite the 1M pulldown on the input - maybe it needs them on the outputs too.

There are other changes that can't be seen - like the dual pot needed for the volume control.
The footswitches were one 3PDT and two DPDT.

[Aharon]

standoffs are from Mouser

561-LAD250               Eagle PCB Posts/Guid    ADHESIVE PC SPT 1/4"

I see now that Small Bear has them too.
Aharon

[Pushtone]

Great build report! 
Thanks for all the detail, very timely.
Excellent looking build too.

I totally dig putting pyramid power under the hood for extra mojo ...


but really, whats the pyramid for? Shielding?

[alderbody]

Very, very good!

only, i could use a bit more "swoosh".   

did you apply jc's lamp driver tricks? i believe you can squeeze some more "juicy-vibe" tone from it.

(or it was just the clip...)

great job! (i see you used the Signature font )

[3/4 North]

Great build report! 
Thanks for all the detail, very timely.
Excellent looking build too.

I totally dig putting pyramid power under the hood for extra mojo ...


but really, whats the pyramid for? Shielding?

That's the light shield, I thought it would reflect the light better on the LDR's

I put the 47k resistor in for swoosh - I had a 50k trimmer there but I liked best turned all the way so I just replaced it. 4k7 - 10k didn't do anything for me.

[axg20202]

Nice build! I'm now tempted to try the stereo mod on my own recently built Neovibe. The only slight problem, if you can call it a problem, is that I find that my neovibe sounds so much sweeter with some gentle crunchy overdrive before or after the neovibe. However, I think the best tone is had by placing the drive AFTER the Neovibe. This is a shame because it presents the problem of how to add the (mono) drive to the stereo outs of the Neovibe (without having one OD per channel, obviously). I'm not sure why I'm posting this - it's just something that has occurred to me while thinking about how to insert a stereo neovibe in my setup.

[axg20202]

That's the light shield, I thought it would reflect the light better on the LDR's

Quite cool. I ended up using the 35mm film can approach on my build which was very easy to work with compared to the sheet metal option I think - also you can get them free from any photo processing lab if you just ask for some.

[wcampagner]

Hello,



Sorry for bring such an old topic back, but i'm planning to build a neovibe with some mods, and there is somethings i didn't understand about these mod... so let's go...



First mod: stereo mod.

It's ok... i understand how to do it... i just want to ask about the volume pot... in the stereo mode i need to change to a dual pot instead of a single pot, ok??

the two buffers used here on the second daughther board are for the two chanels? (stereo) ok?

i didn't understand the 100 ohm resistor conected to the lamps... what's it?

i also want to know if it is possible to use both outputs when the pedal is in bypass mode...



Second mod: led pulsating.

This is ok too... i understand how to conect with this thread: http://www.diystompboxes.com/smfforum/index.php?topic=55655.0

what i want to know if it is better to build a buffer for the led not to harm the lamp...



Third mod: chorus and vibrato led.

This is ok too... the same topic above explain how to do it...

The only thing i want to do is when you switch the effect on/off both leds turn on/off...

To do this the only way that i see is to use a 4PDT to switch everything... is it allright?

But I don't know if it is good... maybe the chorus/vibrato led should be always on... I don't know...



Fouth mod: unit gain and improve the input preamp.

Reading the R.G. article it is done changing the value of two resistors and adding an input buffer...

I think the first daughther board does it...

I just didn't understand the following in and outs: JFET gain in / JFET gain out / Buffer in / Buffer out...

And in the buffer in section of this board... the 47k resistor is not connected to anything... is there a way to post the schematic of both daughther boards??



Thanks a lot in advance,

Wagner.

[3/4 North]

Hi wcampagner,

It's been a while since I built this thing (it was the last pedal I made - amps are a lot more fun)

1 - 100 ohm resistors to lamps are to lower the voltage on the bulbs (if I remember correctly) otherwise they would burn out - the resistors were 3 watts maybe? I can't remember, but the 1/4 watts would start smoking.

2 - a buffer for the lamp, I'm not sure.

3 - I can't remember the switch wiring - it did have a pop I never resolved

4 - I thought the input buffer would improve the gain too, it did very little as far as I could hear.  It can probably be left off.  The second boost did much to improve the volume and tone - although switching it in is the source of my "pop" I couldn't get rid of.

I couldn't run to both amps in bypass - something I didn't try to resolve - I thought of this as a studio effect not something practical to gig with. 

[3/4 North]

The 47k resistor is suppose to connect to the 220k resistor to the right