Aldrin Volume

[Chuck D. Bones]

To those of you who have built the Aldrin (Lunar Module), does it go loud enough? I'm getting ready to build one and I'm wondering if Q3's collector resistors should be altered to increase the volume. I know Skreddy did that on the Hybrid Fuzz Driver.

 

[Barry]

It's on my bench to do, so I'd be interested, too.

 

[phi1]

Depends how much volume you consider enough I guess. I built it from tagboard and have never struggled to get unity or a bit of boost, even at low/medium gain, and I don’t think I ever push the vol knob past 1:00 or so. So it might not have gobs of volume if that last what you’re after, but plenty for my taste.

I also ended up with a BC109B in the first stage to make the low and medium gain tones easier to access.

 

[Chuck D. Bones]

you could also make R5 bigger if you want to reduce the max gain in the 1st stage. Or increase R8 to reduce how hard the 2nd stage gets hit. Skreddy raises R8 to 10K the HFD.

I ended up answering my own question. I compared the Screw Driver and the Hybrid Fuzz Driver. The HFD should have higher volume due to the difference in 3rd stage collector resistors, but the difference was very minor. On both pedals, unity was between 10:00 and 11:00 for a guitar with fairly hot humbuckers on it. I'm keeping the collector resistors stock on my LM. I did some calculations, swapping R11 & R12 gives 11dB more volume. For something milder, change R11 to 4.7K and R12 to 7.5K for 5dB more than stock.

 

[Barry]

you could also make R5 bigger if you want to reduce the max gain in the 1st stage. Or increase R8 to reduce how hard the 2nd stage gets hit. Skreddy raises R8 to 10K the HFD.

I ended up answering my own question. I compared the Screw Driver and the Hybrid Fuzz Driver. The HFD should have higher volume due to the difference in 3rd stage collector resistors, but the difference was very minor. On both pedals, unity was between 10:00 and 11:00 for a guitar with fairly hot humbuckers on it. I'm keeping the collector resistors stock on my LM. I did some calculations, swapping R11 & R12 gives 11dB more volume. For something milder, change R11 to 4.7K and R12 to 7.5K for 5dB more than stock.

C9 is 500pf would a 470 or 560 be a better substitute?

 

[Chuck D. Bones]

Either one is fine, you're not going to hear the difference. C8 has a much stronger effect.

FYI, compared to the Screw Driver and the Hybrid Fuzz Driver, the Lunar Module is definitely the brightest of the three.

 

[Barry]

Went with the 470, jinxed myself and boxed it up before testing and it's the first build I've had in a long time didn't fire right up