John Hollis Ultra Flanger problem

[Baldric]

Hi Guys,
Have any of you successfully built the Ultra Flanger? I built it last week and I can hear the LFO clock coming through with the guitar. When I turn the rate up it is more noticible as the clicks are closer together. I asked rx5 and he recommended building a new LFO. I'd rather try to get what I've built working though. I'm using the pcb from http://www.geofex.com.

Any help would be greatly appreciated, thanks,
-Baldric

[Aharon]

I built the Ultra Flanger with same results,the ticking is very noticeable.
I have heard of others in this forum with the same problem.
The Zombie chorus had it too untill MArk HAmmer came up with a solution,the problem was the uneven voltage divider feeding power to the chips or something to that effect.
I would really love to have this problem solved but it's beyond my knowledge.
MAybe the kind gurus will take pitty on us an come up with a clever solution.
Aharon

[Mark Hammer]

Looking at the layout/schem over at geofex, the Ultraflange  uses a more complicated design to provide the bias voltage to the BBD.  In this instance, it is the combination of Vref and some diodes that do it.  The reference voltage that the BBD derives this bias from is different and separate from where the LFO gets *its'* reference voltage.

Although it is clear that the LFO is not centred around exactly 4.5v, which would suggest the same source of ticking as the Zombie, it would seem from other aspects of the design that it is not intended to be centred around 4.5v.  In the case of the Zombie, one Vref is provided that works fine for the BBD but wreaks havoc on other aspects of the circuit.  Here there is an attempt to do what's right for different parts of the overall circuit, so I am reluctant to recommend the same fix for the Zombie and Ultraflange.

That's the long way of saying I'm stumped.

On the other hand I'm a long way from being the foremost authority on such matters so my stumpification says nothing about the feasibility of a solution.  Just be prepared that it might involve more than a simple component replacement.

[Baldric]

Hi Mark,

Thanks for the help. I'll try out the Zombie fix and see if it helps. I don't see how I can make it sound any worse  

I'll let you know if it fixes it. If anyone else has suggestions on getting rid of the ticking please let me know.

Thanks,
-Baldric

[Baldric]

Well I tried the zombie fix, but it didn't fix my problems. Anyone else have any ideas?

Another question, why do some LFO use LDR's and LED's, what does that do?

[george]

Another question, why do some LFO use LDR's and LED's, what does that do?

I don't think an LDR and LED combination is part of the LFO.  What happens (eg in the case of John Hollis' Easyvibe and 3ms Phaser Fleur, both phase shifting effects) is that the LFO is used to provide a varying voltage to the LED.  This causes the light intensity to vary (this response is fairly linear to the voltage with an LED within a certain range) and in turn to cause the resistance of the LDR the LED is coupled with to vary.

In the case of a phaser, the LDR is part of an RC network. The varying resistance causes the frequency response of the RC network to vary.

For more info I recommend you check out RG's 'The Technology of Phase Shifters' on //www.geofex.com

hope this makes sense ...

Regards
George

[rx5]

Hi guys, got a Q for yah....

Does the LFO from the UltraFlanger work???

mine didnt seem to but when I connected it to another LFO, It worked....

thats why I discarded the orig LFO and got another design for it... and I used 4.5 ref voltage for the LFO.....

to this day.... I modded my flanger to be switchable...from flanger to chorus...thats a 2-in-1 got also another LFO installed...the first LFO was the 'normal' ramp lfo and another...my modified "hyper" LFO...using LE/LDR to control the RATE....I also installed a "mix" switch which mixes both LFO outputs.....

and I added a highpass filter and "depth" op-amp circuit.... and have successfully included a jfet bypass/effect..... only needs a transistor flip-flop as the on-off logic control......

another: HOw does the "MANUAL" knob work?? I mean what does it do to the circuit?? how does it affect the sound??


thanks....



-Ralph

[Baldric]

Isn't manual just the delay under the sweep depth as explained here: http://www.harmony-central.com/Effects/Articles/Flanging/

Cheers,
-Baldric

[rx5]

Baldric,

I think it is?? the manual.....  :roll:

have you made the ultra-flanger??    


-Ralph

[Baldric]

Yeh, I made it, but it still has that noisy LFO signal coming through.

[puretube]

maybe just a parasitic coupling of the "ticks" of the schmitt-trigger part of the LFO including the wiring to the speed- or depth-knob and or to an indicating "flashing" LED (if used). into the audio-path...



//www.puretube.com

[gorohon]

HI,
I've built  Hollis' Ultra Flanger and it worked to a degree and then died.  When it worked it had that infamous Hollis "tick", but having built a Zombie before, I half expected this.  What I found troubling was that it also acted like a distortion pedal.  I couldn't figure it out.  I checked the voltage points and must've messed something up, because now it just swishes back and forth with no audio signal coming through.   Any ideas will help this greenhorn out.

GDK.

[puretube]

maybe there`s a little help for you in the following link (Zombie-issues):

http://diystompboxes.com/sboxforum/viewtopic.php?t=11870&postdays=0&postorder=asc&start=0

[gorohon]

Thanks for the pointers.  I added the third trimpot to adjust the analog bias and replaced r16 and r15 (according to the instructions at geo-fx).  However, this did nothing.  I've teaked up and down--nothing.  My NTE 1641 works (I put it in my zombie and it did fine) and just for kicks put new tlo62 opamps and cd4049 and 4046 chips in.  What I have now is some kind of psycho siren , which would be cool if that was what I wanted.  I'm sure I'm not the only one who has had this problem.  My guess is that the LFO is to blame or the regeneration is in overdrive.  Oh yeah,  there is still no guitar signal (until the effect is bypassed) even though there is no open circuit or short ciruit  to be found so far.  If this is still a bias problem, what would be involved in making a direct bias pot for pin three on my NTE1641?  When you do this, do you cut all other traces going to this pin?

GDK :?

[gorohon]

Well, it finally works.  I guess I'll have to check my parts before I solder them in. I did a systematic check of every part.  A couple of resistors were way off of their advertised value.  I also remelted each solder-joint  to be thourough.  Now,  I have a flanger/Timex.  It ticks so well that I don't  need to look at my clock on the wall anymore!  Oh yeah,  any body know how to mod this to make the sweep even wider?

GDK

[deadastronaut]

quick question, im breadboarding up the ultra flanger..never played with flangers so figured i'll play around with it......

i have a cd4049ube is this correct?...i read that it might need to be a 4049  ?

will it work with the 4049ube? or not?  going by what ive read the ube means unbufferd yes.



cheers guys....

[Scruffie]

Yes, that'll be fine.

[deadastronaut]

brilliant cheers scruffie.....i'll crack on then..