The Amp Garage

HAD used different relay PCB's for the OD and PAB, which seems silly when a generic board can be used for either. The connections in the boards .pdf use the universal relay PCB shown there, or you can use the C/NC/NO references to use any other DPDT relay board.

Dragon1 wrote: ↑Fri Apr 26, 2024 12:45 am What wattage irons are you soldering with, mine is 40 watt and takes a while because it cycles up and down, Doe's anyone make one that doesn't cycle, just stays hot all the time????

What brand/model is the one you are using?

You might consider adding a link in your 102 build thread to its follow-up impressions thread too.

I hope my build threads are helpful to those who want to try but have no background in this... The Q&A leading up to this (six pages) is useful too, and it will get lost if it's not linked: https://ampgarage.com/forum/viewtopic.php?p=464413#p464413 The main filter board looks great! I think this is...

If you are likely to be around 50-100k, I would say go for a 500k trimmer. 10-20% of rotation for the partial boost, and 500k is only about 1 dB down from full lift.

If you are looking at my boards .pdf, you're correct, it uses Com2-NC2 as the path to ground. The layout shows the other set of contacts being used to open the mid pot wiper-CW short, which will have no effect on the PAB if the ground is lifted 22M. Interestingly, if a partial lift is used, then set...

Raoul Duke wrote: ↑Thu Apr 25, 2024 9:10 pm So put the trimmer connecting Com1 and NC1 - one side and wiper?

Yes. You wire the pot as a variable resistor, and when the relay contacts are open it becomes the resistance to ground. If the trimmer is on the bus then there are two ground paths.

The biggest mistake I made when I first started building these amps however many years ago was to try to outwit Dumble with "tweaks" instead of trying to understand his original design intention. It's an urge that I have difficulty with to this day.....but I am working hard not to succumb! To concl...

Yes! Thanks Erwin. Clever way to add that feature.

Reeltarded wrote: ↑Thu Apr 25, 2024 12:48 pm It's always something and always never ends.

This is one of the laws of thermodynamics.

award70 wrote: ↑Thu Apr 25, 2024 3:45 am In a recent YouTube clip he essentially said that if you’re mad that he bought a dumble amp, then the next time one’s up for sale go ahead and buy it.

JB just dropped a notch in my estimation.

Guitarman18 wrote: ↑Wed Apr 24, 2024 6:10 pm This is a really simple and effective way to find the outer foil of your caps.

Sometimes the difference is subtle, so I prefer using a DMM or scope to get a quantitative measurement.

retodellatorre wrote: ↑Thu Apr 25, 2024 8:07 am So i changed the middle pot to a A 10K and removed the 6.8k to ground (just ground)... ... So i replaced the 0.047uf with a 0.022uf - and there we go.

Thanks for the update. Makes sense.

Did Dumble actually do this or is it just another TAG tweak? Excuse me, just another TAG tweak? ;^) I seem to recall seeing a picture of this. It may have been in a HAD amp or maybe it was a mod by one of the commercial D clone builders. Does this mean the full 22M has a negative effect or that it’...

Yes, it's a pot. The switch doesn't remove it from the circuit, just makes it go to the full 1Meg while preserving the setting. Alternatively, a switch in series with the pot could be used to open the bypass circuit and completely remove it, but it would be a good idea to put a large resistor across...