Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Crack-a-two-a => Topic started by: Paul Birkeland on October 15, 2015, 01:44:32 PM
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On the bottom of page 17 and top of page 18, we have accidentally swapped the linear/logarithmic potentiometers.
Please note that the B100K linear pot goes next to the selector switch, and the A100K logarithmic pot occupies the other hole closer to the TRS jack.
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Thanks for being so great about helping me out over the phone. I really appreciate it.
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Thanks for being so great about helping me out over the phone. I really appreciate it.
We appreciate hearing from you and being able to share the corrections with those whose kits are in transit.
-PB
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Quick question, if I accidentally cut a couple of wire lengths a bit long, I'll have enough wire to finish my build, right? How much room for error is included in wiring?
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We add about 10% or more to the total of cut lengths called out in the manual. So if you need to cut 10 feet total you will see 11 on the check list. You might not believe that when reading about builders running short, but we've been throwing extra wire in kits for like 20 years. I have no idea what those guys do with the extra to come up short.
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;)...John
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I think I found another error in the manual. On page 29, it says to add a 220ohm resistor between A9 and 7L. I believe that should be 13L.
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I think I found another error in the manual. On page 29, it says to add a 220ohm resistor between A9 and 7L. I believe that should be 13L.
Yes indeed, that would need to be a very long resistor to reach that far!
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On page 35, the pictures for terminal B and terminal C connections on the selector switch seem to contradict the instructions. Unlike instructed in the manual, the pictures show terminal B wired to the lug closest to the back of the chassis on the bottom row of the potentiometer and terminal C connected to the lug closest to the front of the chassis on the top row of the potentiometer. Are the instructions correct or the pictures?
***EDIT***
I noticed they are both ground, so they must be interchangeable. Is that correct?
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You are correct that it looks like B and C got switched by accident in the text. You are also correct that the amplifier will work wired either way. (Though we'd recommend following the photos on this one)
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I think I found another error in the manual. On page 29, it says to add a 220ohm resistor between A9 and 7L. I believe that should be 13L.
To add to Rocketman248's correction, do not solder the lead of the resistor to 13L yet as it's used for other connections later on during the building process.
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To add to Rocketman248's correction, do not solder the lead of the resistor to 13L yet as it's used for other connections later on during the building process.
To further add to that, the manual never says to solder 13L, but it should be soldered in the first step on Page 41.
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You are correct that it looks like B and C got switched by accident in the text. You are also correct that the amplifier will work wired either way. (Though we'd recommend following the photos on this one)
Will there be any noticeable difference in sound quality? I've already passed this part, and would rather not redo this wiring.
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Will there be any noticeable difference in sound quality? I've already passed this part, and would rather not redo this wiring.
The volume control and balance control will not work as you would expect in terms of how much adjustment you get at a given increment of twisting the knob, but the amplifier will still function properly otherwise. If you've soldered to these, we can send you a replacement pair.
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How does swapping the grounds cause the volume/balance to not work? Also, the wires are the same length. Resoldering them would maybe take 30 seconds.
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Hi just some notes on the circuit diagram, the jack pins appear reveresed, right channel should be the ring, left tip by std connections, the 10,000uF appears lost and B+ Raw leaves the power supplies cd at two places - doesnt make sense would expect as per crack cd leaves after the double r pi or named different if two different feeds. Is there significant deliberate volt drop across the 270R's Also notice the slight change to the 6080 operating point via R1 and R2 changes is this deliberate - to achieve something slightly different? (interested to know)
i read the manual info on the circuit and you have obviously put a lot of work into the hv supply but nil change to the channel circuit - interesting.
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Thanks for the feedback on the schematic. I've corrected the inconsistencies you've mentioned.
The power supply is different because the C2A draws more high voltage current per channel, which would give too much voltage drop through a single CRCRC power supply (and the resistors would need to be 10 Watts), but two separate CRC's that share the first C provide enough filtering for this design and still leave enough voltage for the circuit to operate (note that this would not work in the Crack).
The R1 values haven't changed (still 237/31.6), though the plate voltage of the 6080 is a tad lower than it usually is in the Crack.
The Crackatwoa is intended to elevate the stock Crack circuit well beyond what any modified Crack could ever achieve, while at the same time providing more space and better ergonomics for modifications and upgrades down the road.
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On manuals dated 11-25-15 and earlier, the wire colors on the highest voltage setting are reversed. On page 26, the first instruction should say 22U and the second instruction should say 23U. The pictures are correct.
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On page 57, the text description of the 220 ohm resistor reads - red, red, violet, gold. It should read red, red, brown, gold. The pictures are correct.
Stan
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Um a question I don't want to ask, just finished wiring the input selector and potentiometers and during testing surprised to find that with the white tab of the selector switch turned to the left the right most input is selected and vice versa. I was sort of expecting left is left right is right? I have doubled checked the wiring and as per instructions. (Its ok if I reverse the knob!)
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Sure, reversing the knob shouldn't cause any problems, you'll just have to switch inputs 1 and 3.
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I was being facetious. It just seems rather illogical - the manual could be strengthened by pointing out prior to the hookup what the outcome/ orientation will be.