Dumbleator II
Moderators: pompeiisneaks, Colossal
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UltraHookedOnPhonix
- Posts: 414
- Joined: Thu Dec 15, 2005 9:32 pm
- Location: Dumbleland
Re: Dumbleator II
I'm sure. If you look at the pictures, you'll notice that the blue wire from the power supply board that splits the two 100K resistors leads to both plates of the CF. The two other nodes (red wires) run to the 100K plate resistors.
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GatesofDawn67
- Posts: 16
- Joined: Thu Dec 06, 2007 2:36 am
- Location: Peabody, MA USA
Re: Dumbleator II
Hmmm. I have the same concerns with this schematic that I had with the Two Rock Ruby scheme.
Did Two Rock use a bad Dumble scheme? Did HAD make a mistake in his circuit (Leo Fender's mistakes are crucial to the development of the electric guitar tone--so this is not necessarily a bad thing)?
My concerns are as follows:
Without a resistor between the return jack and the network feeding the return recovery stage, the amount of voltage feedback from the 22M resistor would depend on the output impedance of the FX pedal plugged into the return jack.
Some FX have an active output, who's Z out is 100 Ohms or less.
Some FX have a passive output where the volume control is connected directly to the output jack. A typical value for this pot is 10k. Max Z out occurs when set to -6dB, which would be 2.5k.
This a 25:1 ratio, which corresponds to a 28 dB change in feedback.
My suspicion is that the 220k/?pf parallel combination should be on the other side of the 22M feedback/220k to ground combination.
In other words, return jack to one end of the 220k/?pf. The other end of the 200k/?pf goes to the 22M, the 220k to ground and to the grid of the recovery stage. This also makes the 220k to ground make sense as it it forms a 6 dB attn with the other 220k.
Is the Dumblator known for sounding different with different FX plugged in?
Is this a clever way to somehow compensate for the diff Zouts?
Did Two Rock use a bad Dumble scheme? Did HAD make a mistake in his circuit (Leo Fender's mistakes are crucial to the development of the electric guitar tone--so this is not necessarily a bad thing)?
My concerns are as follows:
Without a resistor between the return jack and the network feeding the return recovery stage, the amount of voltage feedback from the 22M resistor would depend on the output impedance of the FX pedal plugged into the return jack.
Some FX have an active output, who's Z out is 100 Ohms or less.
Some FX have a passive output where the volume control is connected directly to the output jack. A typical value for this pot is 10k. Max Z out occurs when set to -6dB, which would be 2.5k.
This a 25:1 ratio, which corresponds to a 28 dB change in feedback.
My suspicion is that the 220k/?pf parallel combination should be on the other side of the 22M feedback/220k to ground combination.
In other words, return jack to one end of the 220k/?pf. The other end of the 200k/?pf goes to the 22M, the 220k to ground and to the grid of the recovery stage. This also makes the 220k to ground make sense as it it forms a 6 dB attn with the other 220k.
Is the Dumblator known for sounding different with different FX plugged in?
Is this a clever way to somehow compensate for the diff Zouts?
Re: Dumbleator II
Anyone went deep on this project? Maybe some updates
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pompeiisneaks
- Site Admin
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- Location: Washington State, USA
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Re: Dumbleator II
the 'files' section of the forum is for files not for discussion of the particular thing... It would be better if you started a new discussion thread in that area and linked to this page for reference.
Also although not unheard of, it's less common to ressurrect a nearly 10 year old thread, than to start a new one as well and refer to the 'dead' one in forums.
~Phil
tUber Nerd!
Re: Dumbleator II
Sorry about that. Got what I needed, leaving nowpompeiisneaks wrote: ↑Fri Jun 21, 2019 6:24 pmthe 'files' section of the forum is for files not for discussion of the particular thing... It would be better if you started a new discussion thread in that area and linked to this page for reference.
Also although not unheard of, it's less common to ressurrect a nearly 10 year old thread, than to start a new one as well and refer to the 'dead' one in forums.
~Phil