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Problems with Creamy Dreamer

Started by trickpony, May 22, 2012, 04:20:50 PM

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trickpony

Just built a mudbunny creamy dreamer and am having some problems.
The sound I get is very low volume fuzz when sustain and tone are at mid. If I bring them up any
it starts crackling and I get some oscillating volume that goes from silent to very very loud.

I am using the newest pcb. I am using 4  5088s and oriented them per the pcb art. Also using 2n914s (d1-d4) and verified they are correct. Did the diode test on the 5088s and they seem fine. Unfortunately I did not socket anything (next time). Reflowed everything and checked the resistor values.

How should I take voltage readings here? From the emitter to ground?

I looked up past posts and found one that mentioned he couldnt get the creamy dreamer specs to work and ended up subbing the r20-24 resistor values for those in mayo....has anyone verified that creamy dreamer specs work on the pcb?

Any ideas?

Thanks,
Ben

trickpony

So the voltages at the emitters are
q1 4.2
q2 4.1
q3 4.2
q4 0.22

Seems q4 is the problem right? Funny this is the same thing that was experienced by the poster (postie...guy who posted?) and ended up changing r20-23

LaceSensor

I had an issue building the creamy dreamer on the mudbunny etch layout, had to invert q4 or I got that shitty sound you describe. Think there is something up. Once I did that, it was ok.

Read the build doc. If its the etched layout make sure you have all the q's oriented correctly.


trickpony

Well, it's the official pcb ordered from madbean and all the transistors are oriented correctly and the emitter of q4 traces thru to volume and then out...so that is correct.  You may have had the same problem as me, but your "fix" of reversing the tranny just created a pass thru, so you were getting no amplification from that stage...I think. I am going to pull out r20-23 and socket them and try some different values...

Ben

trickpony

Ok, so I swapped out r20 and r23.
I took out the 390R and replaced it with 2K7
and took out the 470k and replaced it with 390K

Now it works!

Soooo, somebody needs to do that math and tell me what happened.
And I think the Creamy Dreamer spec should be changed....or another tranny than 5088
recommended.

Thanks,
Ben

trickpony

Sorry, in my excited haste I think I came off bad.
I meant to say, that I would really appreciate it if someone could explain why the q4 wasnt working with the old values.

Thanks again,
Ben

LaceSensor

Quote from: trickpony on May 22, 2012, 05:42:26 PM
Well, it's the official pcb ordered from madbean and all the transistors are oriented correctly and the emitter of q4 traces thru to volume and then out...so that is correct.  You may have had the same problem as me, but your "fix" of reversing the tranny just created a pass thru, so you were getting no amplification from that stage...I think. I am going to pull out r20-23 and socket them and try some different values...

Ben

The pedal was damn loud anyway, so the pass through fix is ok with me. I assume some resisters were incorrect based on your assessment. nevermind. Big muffs eh. Everyone should just buy the way huge pickle mark 2, its amazing.

BraindeadAudio

Earthbound BEAST/Supercollider FTW....Still trying to figure out how to rig up a mudbunny board to make a Super Collider...any ideas?