Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: phatfish on August 18, 2024, 06:08:01 PM
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Greetings! I recently finished adding the speedball to my crack and I'm loving the sound and the building experience. :) I'd be buying a Crackatwoa if the kit was available.
I currently have balance control on my solid-state phono preamp which I use. I'm planning on building up an Eros2 which I would like to run directly to the crack and fear I would miss the balance control.
Why:
My ears themselves seem to be a bit unbalanced and I prefer to have some degree of balance control even when using a stepped attenuator on my solid-state streaming system. This isn't simply to overcome low volume issues with the stock pot.
The plan:
Add a 100k Balance Pot in series between the RCA inputs and the existing 100k volume pot. Mount it roughly to the left of the vents.
Questions:
Is this a good/sane plan? If not, what is the optimal way to add some form of balance control (within or outside the crack).
I read in the FAQ that the resistance of the pot isn't really important (25k-250k). I'd love to know more about why that's the case. Would adding the balance pot as described make this similar to a single 200k pot?
Any gotchas I should look out for?
Many thanks for any answers and assistance!
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Man, this is such a simple sounding question with a lot of viable answers. There's some good reading here:
https://sound-au.com/pots.htm (https://sound-au.com/pots.htm)
Our kits with balance controls use figure 9 on that page, and I would recommend starting with that.
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Thank you Paul. That link perfectly explains how to wire a normal volume pot for balance control, something I didn’t even know was an option. I was planning on getting a 100k audio note balance pot specifically for this purpose…still might buy great to know there is a much more reasonable option!
I still feel lost about the impact of putting more pots and/or resistance in the signal path tbh. I’m confident it’s a non issue based on other bottlehead products doing this, but I’d like to know what something extreme like adding 10 pots (nothing I would actually do of course) would do? High frequency roll off?
Edit: I suppose at the center position the balance pot wouldn't be adding any resistance, and not much to one channel when slightly off center. I'm still confused why a pot resistance of 25k-250k wouldn't make much difference. Wouldn't the 25k pot offer less resistance at the same position compared to a 250k pot? Wouldn't that affect the audio signal in some appreciable way?
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Lower resistance potentiometers decrease the input impedance of the amp and can load down your sources. Higher resistance potentiometers are more susceptible to picking up noise.
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Have you considered using separate pots/attinulators for each channel? Like the early Foreplay.
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Appreciate the explanation Paul!
2wo: I did briefly consider, but I tend to adjust the volume frequently and the balance infrequently, so I’m quite set on the balance control.
I’m ordering parts and will update here on the results. 8) I appreciate the help.
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Success! Thanks y'all. 8)
The audio note balance pot ain't cheap, but I gotta say I really like the center position feature it has compared to using a regular pot for this purpose. Parts Connexion was also quick to provide a wiring diagram specific to this pot.