MKI Screeching noise?

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Nostalgia
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MKI Screeching noise?

Post by Nostalgia »

Needs some help guys. How do you eliminate the screeching noise in a MKI Tone Bender? This are the specs of transistors. Q1 OC81D 40hfe/60ua lk, Q2 2G381 95hfe/60ua & Q3 2G381 80 hfe/300ua lk.

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devnulljp
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Re: MKI Screeching noise?

Post by devnulljp »

Sounds OK to me. What am I missing? You talking about the kinda gated fizzle at the end there?
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Nostalgia
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Re: MKI Screeching noise?

Post by Nostalgia »

devnulljp wrote:Sounds OK to me. What am I missing? You talking about the kinda gated fizzle at the end there?
Yeah, that noise. I tried putting a 5nf Cap from the input to the ground, that did the trick but it changed the feel and tone. Maybe I'll try to use 2-3nf.
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HorseyBoy
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Re: MKI Screeching noise?

Post by HorseyBoy »

devnulljp wrote:Sounds OK to me. What am I missing? You talking about the kinda gated fizzle at the end there?
Yeah, sounded pretty good to me, too. Was the attack on full? I thought it could use a little more grunt, but Mk 1s are kinda gated, especially if the attack and volume are rolled off.
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superslidetail
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Re: MKI Screeching noise?

Post by superslidetail »

Sounds like a vintage pedal to me. :badteeth: Though my silicon fuzzes made that noise, the germaniums not so much.
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Nostalgia
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Re: MKI Screeching noise?

Post by Nostalgia »

HorseyBoy wrote:
devnulljp wrote:Sounds OK to me. What am I missing? You talking about the kinda gated fizzle at the end there?
Yeah, sounded pretty good to me, too. Was the attack on full? I thought it could use a little more grunt, but Mk 1s are kinda gated, especially if the attack and volume are rolled off.
The attack was maxed, volume was around 2:00. I also biased this very low . Probably -1.5v on the collector of Q2(attack maxed). I also used a 15 watter solid state amp. I have never tried it on a bigger more powerful tube amp yet.

I had just placed a lower gain with lower leakage 2G381 on Q3, now it's very quite. Though I really liked the grittiness of the one with the higher leakage.

Should I use higher gain transistor on Q2? Sadly the highest gain 2G381 that I have right now is only 95hfe.
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Lee
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Re: MKI Screeching noise?

Post by Lee »

Sounds good. Every MKI is different in its own way. Yours sounds good I wouldn't change it.
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Doc Holliday
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Re: MKI Screeching noise?

Post by Doc Holliday »

Sounds like a true mk1 to me. My creepy zonk had a fair bit of pop and sizzle in the decay. I thought that was awesome!
Bret608
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Re: MKI Screeching noise?

Post by Bret608 »

I also think it sounds good, not unlike a Zonk-alike I built that sounded quite similar on the decay. The one thing more you could try in addition to the lower leakage you did on Q3 is maybe try something leakier on Q2, not really worrying too much about the gain (but probably not below 80 hfe is possible). I found if you got below on 2 volts on max attack, it could be a little too gated, and playing with Q2 until I got a sweep of voltages across the attack pot that I liked was the key.

Anyway, if you like it, nothing to worry about!
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Nostalgia
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Re: MKI Screeching noise?

Post by Nostalgia »

I am glad you guys liked how it sounds. I'll do more tweaking to it.
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