Distorted Repeats on Cave Dweller v.2015 PT2399 Delay

[juan_felt]

Hi!

I recently put together Madbean's Cave Dweller (2015 version), following the Layout from TagboardFX (http://tagboardeffects.blogspot.com.ar/2016/09/madbean-cave-dweller-2015.html).

I get repeats, and all the controls seem to be working properly, but I get distorted repeats at all settings.

All the caps i'm using are ceramic. Does this affect the signal?

Thanks for any help!!!

[jimilee]

Not that would cause distortion, have you tried different pt2399s?


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[juan_felt]

I have tried a different one and still get the same distorted sound. Thanks tho!

[jimilee]

If you look at schematics for delays like the deathclaw over at Madbean, they've discovered that if you insert a 3mm green led somewhere around the pt2399 it cuts down on the distortion. I haven't really studied to see where though.


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[bamslam69]

I built one as well. I've noticed the way the delay distorts over time as well, however is this why I've heard the Cavedweller described as "lo-fi"?

Another question, How have you got it powered? battery or power supply? Getting any AC hum from the power supply?

[ElectricDruid]

Is the bias ok on the input buffer JFET? Having that out would introduce some distortion.

Distortion on the repeats is normal for the PT2399, and is much worse with the longest delays. But the clean signal should be ok, especially in this 2015 version.

HTH,
Tom

[juan_felt]

If you look at schematics for delays like the deathclaw over at Madbean, they've discovered that if you insert a 3mm green led somewhere around the pt2399 it cuts down on the distortion. I haven't really studied to see where though.

Jimilee, I have the green LED on the board. It's always off, I'm not sure if it has to lit at some point.

Thanks anyway!

I built one as well. I've noticed the way the delay distorts over time as well, however is this why I've heard the Cavedweller described as "lo-fi"?

Another question, How have you got it powered? battery or power supply? Getting any AC hum from the power supply?

Bamslam69, I get distortion on all settings. It is powered with a regulated and filtered power supply.

Is the bias ok on the input buffer JFET? Having that out would introduce some distortion.

Distortion on the repeats is normal for the PT2399, and is much worse with the longest delays. But the clean signal should be ok, especially in this 2015 version.

HTH,
Tom

Hi Tom, the JFET is properly biased, the clean signal is not distorted, only the repeats.

[duck_arse]

the green led (3mm or 5mm - they both green ......) is not an indicator. lighting, not lighting, no difference. go to the hamlet delay build docs for the origin of and uses for.

[anotherjim]

Maybe your ceramic caps are the trouble, not because ceramic is bad, but because sometimes the value markings are hard to read or understand. Some of yours may be too small.
The 4 caps around the PT2399 pins 7 thru to 12, some of those can't be too small (I think the one pin11-12 in particular) - works best for me 100nF. Too small or missing and it's loud & fuzzy.
So you want caps marked 104 or 0.1u.

[juan_felt]

Maybe your ceramic caps are the trouble, not because ceramic is bad, but because sometimes the value markings are hard to read or understand. Some of yours may be too small.
The 4 caps around the PT2399 pins 7 thru to 12, some of those can't be too small (I think the one pin11-12 in particular) - works best for me 100nF. Too small or missing and it's loud & fuzzy.
So you want caps marked 104 or 0.1u.

Thanks! I double checked my caps, and they are OK.
Still worth trying!

[ElectricDruid]

I built one as well. I've noticed the way the delay distorts over time as well, however is this why I've heard the Cavedweller described as "lo-fi"?

Yes. The PT2399 isn't "hi-fi" at the best of times, and in a simple circuit like the cave dweller, it's definitely not hi-fi. The newer version removes some of the more obvious limitations of the earlier circuit, but the circuit is still a PT2399-based delay with limited filtering and no companding.

Does the distort get worse with longer delay times?

This is a key question because if so, what you're hearing is the inevitable distortion from the PT2399. If not, then it could be coming from somewhere else, in which case you might be able to improve it.

You should also try feeding the effect with different input levels to see if the distortion only appears at a certain volume of input. That might give s another clue.

HTH,
Tom