Easyvibe scooped, shrill, grainy

Started by Craggles, May 19, 2016, 03:22:03 AM

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Craggles

Hey guys, I built an Easyvibe from the geofex layout last year, and now that the honeymoon period is over (I've actually started to critically listen to it rather than simply revel in the vibey goodness), I'm not happy with how it sounds in Chorus mode.

In Vibrato mode it's fine. I can click it on (true bypass, not millenium) and there's no change at all in frequency response. It just wobbles, with no graininess, like it's meant to. Think Hendrix's "Hey Baby / New Rising Sun" or "Pali Gap".

In Chorus mode though, even with the depth doing nothing, there's a really significant tonal shift - not much bass, mid hump with a shrill/biting/kinda lo-fi high treble, and then as I turn the depth up it knocks the mids down, sweeps nicely but has a grainy texture. There's no sweet spot on the bias/drive control that makes it sound like the full range of my clean signal is vibing. It sounds way more coloured than the vibrato mode. Kinda hard to explain in words, but in the Chorus mode, depending on the depth setting, it's basically too scooped when vibing, and too humped when not vibing (but engaged). Why wouldn't it sound like my bypass signal if the depth is on zero?

I did swap out the drive trimpot for an external 5k control, but at minimum setting it has good bass but poor mids and highs, and at full rotation it's mega thin. In between, I can't seem to find a decent balance.

I've spent about 4 hours reading through every possible search result on here, but other than swapping the input cap from 0.001 to 0.01 or putting a low pass at output, I haven't been able to find any fixes. Seems most people say this is the nature of the beast. If so then that's cool, but I'm a bit confused as to why the chorus mode would sound so different from the vibrato mode if the input/output freq filtering was an issue...

I've considered gutting it and installing a buffered blend around the circuit to try and retain some of the clean signal while in Chorus, but this is drastic surgery and I'd rather not.

Anyone else find their Easyvibe does this? Any suggestions on what could be wrong? All voltages check out, and as I said, the vibrato mode sounds peachy clean and beautiful. Maybe start by swapping out the two ICs in the Chorus circuit?

Thanks in advance :)

JerS

For what it's worth, I don't find mine grainy or shrill at all. Mine sounds like a nice phaser with a "lumpy" sweep - just like a univibe. I have built many easyvibes and find them to be quite consistent.

Certainly the tone of the guitar changes - the phase cancellation is part of the effect. But I did not find it to sound overly trebly. In fact at the low end of the sweep, it gets quite deep bass.

Cheers - Jeremy