Glasshole - serious boo-boo

[bloozer]

On the Glasshole schematic, the collector of Q1 and R46 connect to a net called VC. Unfortunately, this net goes nowhere, therefore there's no power to Q1. I was wondering why the LED D2 seemed to turn off and on abruptly rather than ramp up and down smoothly and why the trimmer T1 didn't seem to do much. It turns out that with no power to the transistor the LED is being driven by the opamp and the LED is off during the entire negative cycle of the LFO. I was able to fix it by adding a jumper between the anode of D9 and the near end of R46. Now I'm able to adjust T1 to drive the LED with a nice triangle wave.

[mjg]

It should connect to the +VC net.   So yeah, the jumper you have added would do that. 

[danfrank]

Very interesting!
I had my glasshole on a scope a few weeks ago and couldn't get the waveform to look right, I bet this will solve that.
Thanks!

[madbean]

Oh dear, you are exactly right. There's a mistake. I know exactly what happened, too (I made some changes from my prototype for the final production board and that's when the error occurred - I changed the net it connected to but named it incorrectly).

I'll get the correction notated and put the fix in the doc, with an explanation later today. Thanks for bringing it to my attention.

[bloozer]

I'm glad you were able to update the PDF so quickly. BTW, I was unable to recover the password for my original account. I tried so many times that the forum eventually blocked me. This isn't the first time this has happened to me and I've given up on this in the past. But this boo-boo was serious enough that I went to the trouble of creating a new account with a different email address.

On a positive note, I've built a bunch of these projects over the years with excellent results. Keep up the good work!

[danfrank]

Ha ha, you've been demoted to "diode destroyer"!
Seriously though, thank you for posting this, my GH now works beautifully.
Thanks again

[bloozer]

The Mu-tron Phasor II is one of my favorite phase shifters and the Madbean version adds some new colors to it. Now, if we only had a Madbean version of the Bi-Phase . . . (hint hint)

[gordo]

Kinda funny that I was worried this was going to bugger up my favorite sound on this thing so I was prepared to add it on a switch.  I use the CCW most setting on the rotary with no feedback and about 2/3 depth for a "is this thing on?" kinda wobble.  I'm happy to report that it didn't but I'm also able to get the swooshy stuff that the original does with more stages.

I know....I should probably just use a Phase45 but I like blinkey lights and this sounds a tad evil to boot.

[danfrank]

The Mu-tron Phasor II is one of my favorite phase shifters and the Madbean version adds some new colors to it. Now, if we only had a Madbean version of the Bi-Phase . . . (hint hint)

For those of you with a scope, the build docs for the dead end fx lola phase has great calibrating instructions that can be applied to the GlassHole.
One more thing... Since I placed the jumper, when the effect is turned on I have a noticable increase in volume. Has anybody else noticed this?

[madbean]

The Mu-tron Phasor II is one of my favorite phase shifters and the Madbean version adds some new colors to it. Now, if we only had a Madbean version of the Bi-Phase . . . (hint hint)

For those of you with a scope, the build docs for the dead end fx lola phase has great calibrating instructions that can be applied to the GlassHole.
One more thing... Since I placed the jumper, when the effect is turned on I have a noticable increase in volume. Has anybody else noticed this?

Since that part of the circuit only deals with the LFO to drive the LED I don't see how it would impact volume. Unless, maybe your phased stages have gotten noticeably louder due to them working properly. Is the dry volume also increased?

[danfrank]

That I do not know, unfortunately. Before I placed the jumper, the bypassed and effect volumes were pretty much even. Now, the effect engaged is definitely hotter.
How can I check?? Should the signals at pins 5 & 6 of IC 1B be equal in magnitude? I'll check that out.

[bloozer]

Mine might be a dB or two "bassier" when the effect is engaged in the 2 and 4 stage settings, not so much in the 6 and 8 stage settings. I probably wouldn't have noticed if you hadn't mentioned it. I wouldn't say it's a dramatic difference. It's nice to have a little boost when you kick in an effect.

[Scruffie]

Peaks & Notches, notice how the output diff-amp is already set for slightly reduced gain? Try turning those 8k2's in to 7k5.