Speedball Upgrade Removal?

rivendell86 · 922

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Offline rivendell86

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on: October 24, 2019, 10:59:55 AM
Hi, very amateur electronic diy guy here,

I completed the Crack base kit recently (thank you again for the assistance on the forum) and then a few days after getting some listening time in, proceeded to install the Speedball upgrade successfully, passing all resistance and voltage checks. 

I want to start by saying, I can certainly hear the difference, and why it is an upgrade. But, and though I'm not 100% sure here, I think I preferred the ease and smoothness of the sound prior, versus the more upfront, accurate, and aggressive sound now, if those are apt enough descriptions. And this may just be my fickle mind, or a grass is greener moment, but I may not be able to let this go until I know with more sureness.

I also followed the Speedball guide's suggestion after the first half of the build (install of the small circuit board), and spent some time listening to the amp at that juncture; that may have been my favored sound to come from the amp of the 3 phases (base, speedball 1/2, speedball complete).

I considered buying another base Crack to have both sounds, because I enjoyed the project so much and love the amp regardless of the aforementioned. But in effort to save a little coin...

I thought to completely remove the speedball, but I clipped the 22.1K 1/2W resistors leads too much to reuse them. I know they're probably cheap but I was having a little trouble ensuring I'm getting the right ones online. That brought me back to the idea of just reverting to speedball phase 1/2 (my 3K 10W resistors' leads are still intact)

My questions are, would you ill advise this plan? Or can I revert back to that phase no problem, as long as my build and voltage checks line up again with the manual there? And is it safe to run the amp at that build indefinitely?

Might you briefly explain what the theoretical/actual sound difference is between Speedball 1/2 phase and the completed Speedball?

Thank you,

Max



Offline Paul Birkeland

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Reply #1 on: October 24, 2019, 02:10:26 PM
The first half of the Speedball (the small board) increases the gain of the Crack a bit, decreases distortion in the driver stage significantly, and may slightly lower the noisefloor.

The second half of the Speedball (the big board) increases the available AC current in the output stage that can pass through the load (your headphones). 

Any old 22K 1W resistor will work to replace the ones we provide.  You are correct that they are not particularly expensive.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man