Neovibe Sounds...

[SteveB]

Hello! I just finish one neovibe and it's great, need some tweaking. There is one question that puzzle me: how do you manage to have The 391 ohms lamp bias ? Do you use a 500ohm trimpot for bias (I have a 200 ohm). I mesure between Q13-E and ground (the O point on the GGG board) and I have mesure from 68 to 270ohm... Do I measure to the good point?

Yes, with those values you are measuring, I believe you are measuring at a good point.

I used to have a 500 ohm trimpot in mine. It was always a bit tricky to fine tune, so I measured the resistance after finding what sounded good to me. I replaced R48 with a 330 ohm resistor, & used a 100 ohm trim pot for fine tuning.

Of course, it all comes down to what sounds good to you. Maybe you could try a 150 ohm or 220 ohm resistor for R48, adjust the trimpot, & see if you like the sound?

Steve

[dantahoua]

Thanks!  I'll try that. I also change the two 4.7k 'speed' resistor to 1.2k but the fastest setting is not very faster... Probably the bulb, but I would like to manage to bias it well before looking everywhere on the board! I used only 3904, but I have a bunch of 5088, I'll probably replace Q1 with 5088, seems to be good as I read on the forum.

[dantahoua]

I'm a little bit confuse  with two "slow" enhance that I saw on this forum and with the biasing:

-The one that involve the 2M2 Bias Feed resistor in the Oscillator to be increased to 5Meg or more.
-Or The one with the 100k trim pot on R47
If I understand well, the second one will act as a second bias on the bulb but just for the dark side.
Does this two mod compatible? Or just the first is enought? I want to be able to use the pedal at very slow speed without loosing too much bright (aka Pink Floyd Breathe).

-And my last question, is there a particular way for setting the bias (still with a 200ohm + 68ohm in my case, but I'll change it if necessery) properly? Do you have to do this by ear? When I set it to the max (in my case 270), the sweep is some kind of good but the sound become darker (less high, less brillant)... I think it depends of the bulb and transistor (in my case only 3904 everywhere, but I have a bunch of 5088 in stock).

PS: I manage to get a very nice "top" speed with 1k2 resistor in place of the 4k7. Great!
Thanks!

[juse]

Hey Steve - flamebait and swoopy are awesome...... 

[dantahoua]

Some enlightment to my questions?

[SteveB]

I'm a little bit confuse  with two "slow" enhance that I saw on this forum and with the biasing:

-The one that involve the 2M2 Bias Feed resistor in the Oscillator to be increased to 5Meg or more.
-Or The one with the 100k trim pot on R47
If I understand well, the second one will act as a second bias on the bulb but just for the dark side.
Does this two mod compatible? Or just the first is enought? I want to be able to use the pedal at very slow speed without loosing too much bright (aka Pink Floyd Breathe).

-And my last question, is there a particular way for setting the bias (still with a 200ohm + 68ohm in my case, but I'll change it if necessery) properly? Do you have to do this by ear? When I set it to the max (in my case 270), the sweep is some kind of good but the sound become darker (less high, less brillant)... I think it depends of the bulb and transistor (in my case only 3904 everywhere, but I have a bunch of 5088 in stock).

PS: I manage to get a very nice "top" speed with 1k2 resistor in place of the 4k7. Great!


Thanks!

I'm not familiar with the 2M2 biads feed resisitor mod.

As far as the other one, I'm not a tech propeller-head or engineer, so my explanation will be based on assumptions & experiences with the sound. In my vibe, the brightest part of the bulb swing produces a "wow" sound, simlar to a wah-wah pedal. When I would adjust the bias & instensity to minimize the "wow" sound, it was good, but maybe not as deep as I would like. Also, I found that some of the frequencies & phase cancellation I liked happened when the bulb was on the dark side of the swing. I added the trimpot to R47 to experiment with adding more resistance to the bulb to see how it would affect the sound. It was so easy to do.

So much of the sound depends on ow the bulb reacts & how the photocells respond. I had cheap Radio Shack photocells in mine for years & now have Silonex NSL 7350 cells in it. When I made the change, there were differences, but nothing earth shattering. Maybe if I would do an A-B comparison the differences would be more apparent, but I'm not going to at this point.

So, with all that said, my settings may not work for yours. All I can suggest is to experiment. I'm more of a musician than a pedal builder, so the end result is what really matters to me. Every adjustment I do is based on sound, not necessarily meter readings. I posted the readings as general information, not as a hard fast rule to live by. I have read that you should adjust the bias with the intensity all the way down, but I can't do this visually. The term "where the bulb is glowing dimly orange" is a bit too vague, but I understand that it is intended as a starting point. One thing to try is to use your ears. With the intensity down all the way, listen how the sound changes as you change the bias. Maybe try to get it to sound as deep as possible, or as much like your bypassed signal as possible. Then, turn up the intensity, & see what it sounds like. I wish I could help more.

Good luck,
Steve

[piloto117]

  The mods you're getting confused about are two different things.
The 2M2 Bias Feed mod, I believe from what I've read is to enchance or extend the range of the depth of the effect but at slower settings (rate/speed control).  I personally haven't tried this since I think it's deep as it should be for my tastes...
the second mod you're talking about is (from what I understand) is Steve B's "simplified offset bias" mod, where he took a 100k trim pot and attached it to R47(?).  I think he got the idea from the JC mod (from another project), or maybe he got the idea by himself fiddling around with that resistor, because I think (I'm no expert, but have spent a lot of time on the project) it controls the way the bulb is flashing.  Try to imagine a normal bulb in a room and you're flicking the on/off switch constantly, now try to imagine the same but instead you're using a DIMMER...see how the effect is "softer" for your eyes?  It's something similar....the higher the resistance the "softer" it sweeps. I definitely recommend it .  It helps finding the sweet spot for your univibe. 
  The cells themselves and bulb have a big impact on the sound as well, I know this has been covered before but try experimenting with the POSITION of the cells (facing directly or indirectly at the bulb), the DISTANCE from the cells to the bulb if facing directly at the bulb, the HEIGHT and TYPE of reflective material if using indirect light, etc.

  As far as setting the bias, I guess Steve is right; you have to use your ears for that not your DMM, LOL.     I did the following:

Start by setting the trim pot to get a dark orange on the bulb with the depth knob all the way down and the speed knob on a slow to medium setting; adjust it to taste (meaning how dark is up to you), and then slowly start to get the depth knob up hearing how it's affecting the sound.  Once you've got that covered, adjust the r47 trimpot with the rate knob set to a medium to fast setting , like I said before the higher the resistance the softer the swing.  I've noticed that if you set your bulb too bright it can start sounding like wah wah which I particularly like with a clean setting, but no so much with a dirty sound.  So i try to balance that out sticking more on the dark side.  The r47 mod is a MUST, no matter what (for me), because it defines the "character" and "harshness" of the swing, dunno how to describe it, but just do it!

  I would like to take this oportunity and publicly say thanks Steve, I've been reading a lot of posts and threads on the neovibe and you're definitely a great reference (info and clips) for this project.

Hope this helps clarifying your questions.
Good Luck!

[dantahoua]

Many, many, many thanks to you both! You gave me some very good point, and I know my ears have to work!  I read almost all subject on the neovibe in the forum, and your information are just the little bit I needed. I'll do it tomorrow and keep you in touch. I'll probably start a new thread with picture, sound and information, just for the other to come! Many thanks ! This forum is a must! 

[bpier]

Hi. Here is a small sample of my neovibe that uses also NSL 7350's from Small Bear. I've used on this small sample a Tokai strat springy sound, in a Fender Hot Rod, via a SM57, with a Vox Clyde original and a tube screamer. Pierre

http://sd-1.archive-host.com/membres/playlist/104029455159992169/Neovibe/Vodoo_Child_neovibe_clyde.mp3

[dantahoua]

Great sample! Good playing! I'll posrt some sample comparison between EasyVibe, Neovibe, Mini Deja Vibe, Mofaux Vibe and MicroVibe. I'll keep the community in touch when it's done.

[bpier]

An another comparison, very good idea !

And another sample :
http://sd-1.archive-host.com/membres/playlist/104029455159992169/Neovibe/test_neovibe.mp3

[SteveB]

An another comparison, very good idea !

And another sample :
http://sd-1.archive-host.com/membres/playlist/104029455159992169/Neovibe/test_neovibe.mp3

Ah, very nice clean sounds! Thats one thing I never managed to record for mine. How was the intensity set on most of the clips?

Steve

[bpier]

Thanks steveb. On the clip, the depht is generally at the maximum. Pierre