Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: rhoninkor on October 08, 2019, 09:02:15 AM
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Dear BH community:
I recently assembled my first Crack set (without Speedball), passed all tests, and works like a charm. Then like many people, I also purchased some additional 12AU7 output tubes to try them out from TubeWorldExpress.com. Here is a list of tubes that I purchased:
1. 5963 RCA used/good (50 in stock) × 1
2. (!) 12AU7A Matsushita JAPAN 1960's used/good no printing (8.6/10.2ma) (similar sound to Mullard) - 12au7 × 1
3. (!) (#1 12AU7 BEST VALUE SINGLE) ECC82=12AU7 RFT East Germany branded "W" Funkwerk NOS 1970's (9.4/10.6ma) × 1
4. 12AU6 Amperex Bugle Boy England used/tests like new 1963 (11ma) (recommended) × 1
I only tried the first two tubes, but the RCA is giving me some noise on the left channel. It's like static noise, but it's come-and-go so not persistent. The Masushita tube also gives me a little noise on the left channel, but not as bad as RCA. Both cases are not terrible, but just a little annoying. Is there anyway for me to debug the cause of this? How can I tell if the tubes themselves are not good? I haven't tried the other two tubes yet, but will update later.
My other questions are on the two LED lights. I cannot see them from the front side of the amp, what are the use of them? Am I installing them correctly? Thanks!
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The noise that you're describing could be tube related and may go away if you run each tube for 50-100 hours. It could also be a flaky solder joint in the amp that's producing some noise.
The LEDs are not to look at. They provide the bias voltage for the 12AU7.
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The obvious question is, do you now get the same noise with the original tube? I assume it wasn't there before you tried the new ones. You have two more to try. If then all four make noise and maybe your original one as well it sounds as if you have loosened off a solder joint somewhere.
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Dear BH community:
I recently assembled my first Crack set (without Speedball), passed all tests, and works like a charm. Then like many people, I also purchased some additional 12AU7 output tubes to try them out from TubeWorldExpress.com. Here is a list of tubes that I purchased:
1. 5963 RCA used/good (50 in stock) × 1
2. (!) 12AU7A Matsushita JAPAN 1960's used/good no printing (8.6/10.2ma) (similar sound to Mullard) - 12au7 × 1
3. (!) (#1 12AU7 BEST VALUE SINGLE) ECC82=12AU7 RFT East Germany branded "W" Funkwerk NOS 1970's (9.4/10.6ma) × 1
4. 12AU6 Amperex Bugle Boy England used/tests like new 1963 (11ma) (recommended) × 1
I only tried the first two tubes, but the RCA is giving me some noise on the left channel. It's like static noise, but it's come-and-go so not persistent. The Masushita tube also gives me a little noise on the left channel, but not as bad as RCA. Both cases are not terrible, but just a little annoying. Is there anyway for me to debug the cause of this? How can I tell if the tubes themselves are not good? I haven't tried the other two tubes yet, but will update later.
My other questions are on the two LED lights. I cannot see them from the front side of the amp, what are the use of them? Am I installing them correctly? Thanks!
Clean the pins.
https://www.amazon.com/CAIG-LABORATORIES-D100L-25C-Contact-Cleaner/dp/B0000YH6F8/ref=pd_sbs_469_t_0/138-0687618-8750239?_encoding=UTF8&pd_rd_i=B0000YH6F8&pd_rd_r=7bf6b2d1-7e4b-4c4c-b83b-7a5123149fce&pd_rd_w=tTFAl&pd_rd_wg=xGcqq&pf_rd_p=5cfcfe89-300f-47d2-b1ad-a4e27203a02a&pf_rd_r=4CSXBQ7AAX3TFD88B38Y&psc=1&refRID=4CSXBQ7AAX3TFD88B38Y