Whilst ordering parts for my harbinger build, I was looking over schematics of the original univibe. I noticed that MB's R46 is listed as 47k, but in the original it seems a 4k7 was used here. Is that right (or has MB changed the value for a particular reason?).
It was mentioned in a thread a few weeks ago, I think it was Pryde he said something about socketing that resistor so you can try both.
Found it: 2
Projects / General Questions / Harbinger One: Circuit is Done. One small issue
on: April 15, 2013, 02:56:12 AM
Started by pryde, Message by pryde
Relevance: 51.5%
Just finshed the harbinger one circuit and got it dialed in very nice so far I think.
At first I was getting very little modulation and the lamp filaments were barely glowing. Luckily I socketed R46 and swapped the 47k for a 4.7K...That was it! More brightness and much more effect ofcourse. Everything else is per the build doc for 9v option. Still messing with gain/ramp but getting some great sounds. I do have to say I am not finding the chorus very appealing but the vibrato is excellent. I pointed the photcells directly at the lamp and made a reflective sheild with a plastic cap that was the right size.
SOCKET R46 !
The issue I am having is the LED function. When jumpered the circuit works great; however, when trying to run an LED there is very little/no effect and the LED light just stays on and does not pulse with the speed control?
Thoughts?
Mike
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jvg13
QuoteConcerning your prob Mike with the LED - I personally wouldn't know, sorry (have you tried initial things like double-checking the LED is the right way?).
No I don't have any problems with my Univibe (yet!!)which I am still building, that was part of the quote from Pryde. :)
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Yes I put 4.7 k in R46 also. It did the trick! When I had 47k in originally, the unit was very tame, barely producing any effect. But after I swapped it for 4.7k, WOW !!!! I was swimming in an ocean of glorious wavy univibe tones.
Had to take seasickness pills from the sloshing sounds. Groovy.....
Also added an spst kill switch to the DC jack. This helps to save the light bulb. The thing pulses all the time, even when you've got the unit in bypass. The kill switch allows you to only power the bulb when you're going to use the effect. ;)
Thanks for all that info John (jvg13). The only real issue I had with the univibe was it seemed to antenuate any fx unit in front or behind it... The chorus side of the switch actually sounds better than the univibe, which didn't impress me very much. I also get some very harsh distortion if the vol is turned up.
Unless I have something amiss with my Harbinger I was not that impressed with it. I will keep messing with it see what happens...it is early days and I need to probably check it over more closely.
Well after reading the Technology of the Unvibe by RG Keen...which is really worthwhile, it gives you a good understanding of how the Harbinger works. If I had read it earlier before I built it I definately would have done more socketing. Anyway,I feel a lot better as it has funnily enough helped me sort my Harbinger :)
I replaced Q1 in the input preamp stage with an MPSA-A18 transistor, I now have a cleaned up signal and a lot more gain without the harshness. So looks like that was my problem,it now sounds good.
Thanks jvg13, for the link.
Mike
I think there's also a 1n914 missing in the BOM