Crack;Bottlehead OTL
Jun 5, 2020 at 12:52 PM Post #10,066 of 11,339

carlman14

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Hi all! Question for those of you that have installed a choke: how did you mount it? To the faceplate, or with standoffs? Did you do any extra ground wiring or just a simple replacement of one of the 270 5v?

Hey there! I used 25mm standoffs to mount the choke to the faceplate. Something like this: https://www.mouser.com/ProductDetail/693-9832.5200. Female end is screwed into the faceplate, and the holes for the choke's bracket go through the male ends of the standoffs and held in place with nuts. This can also be done with female-female standoffs too.

Yes, it is used to replace one of the 270 ohm 5W resistors. I also added a ground wire going from underneath one of the nuts to ground. For placement, most people mount it such that the screws for the standoffs are just behind the power transformer. You can see those 2 black screws in the back of my faceplate in my pictures a few posts ago. Those are for the choke standoffs.

Hope this helps!
 
Jun 5, 2020 at 1:37 PM Post #10,067 of 11,339

attmci

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I just came into posession of a crack 1.1 With Speedball and Murdof Caps. It came with a selection of tubes. Can anyone recommend me some good combos from this list?

Power valves are:
Mullard 6080 SB CV 2984 KB/D made in England.
GEC valve made in uk, 6080 CV 2984 KB/Z.
Svetlana winged C NOS bottle shape, 6AS7G
Thomson CSF 6080WA ruggedised double power triode.
Philips ECG Jan 6080WC 3 mica.
Raytheon 6080.

Input valves are:
Vintage RCA NOS black plate Aug 1953, 12AU7
Mullard NOS CV4003 12AU7A
Jan Philips ECG 12AU7 5963
Electro Harmonix gold pins 12AU7/ECC82
JJ electronic ECC82 12AU7

Input valves with supplied 6SN7 to 12AU7 ADAPTER.
Tung Sol 6SN7 GTB.
Sylvania 6SN7 GTB
Electro Harmonix 6SN7GT.
GEC 6080, cv4003, 6sn7 to 12au7 adapter.
 
Jun 5, 2020 at 1:45 PM Post #10,068 of 11,339

PsilocybinCube

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GEC 6080, cv4003, 6sn7 to 12au7 adapter.
Wow, you got the hook-up on the tubes. I'm a relative newbie to the BHC, but I purchased a couple of Winged C tubes and am in love with it. For the power tube, it gets my vote.
 
Jun 5, 2020 at 8:33 PM Post #10,069 of 11,339

DenverW

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Hey there! I used 25mm standoffs to mount the choke to the faceplate. Something like this: https://www.mouser.com/ProductDetail/693-9832.5200. Female end is screwed into the faceplate, and the holes for the choke's bracket go through the male ends of the standoffs and held in place with nuts. This can also be done with female-female standoffs too.

Yes, it is used to replace one of the 270 ohm 5W resistors. I also added a ground wire going from underneath one of the nuts to ground. For placement, most people mount it such that the screws for the standoffs are just behind the power transformer. You can see those 2 black screws in the back of my faceplate in my pictures a few posts ago. Those are for the choke standoffs.

Hope this helps!

Thanks! Is there an orientation for the two choke wires or can either wire go to either terminal of the 270 its replacing?
 
Jun 5, 2020 at 8:55 PM Post #10,071 of 11,339

DenverW

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At 1:42 doc b sent out an email about three crackatwoa kits going on sale for 150 off. I didn't see the email until 5:50 and they were gone. Sad face!
 
Jun 6, 2020 at 12:16 AM Post #10,073 of 11,339

DenverW

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Did the choke mod today. Replaced the resistor that crosses the transformer. Why that one? It was easier :). Ran a ground wire from one of the screws holding it in place. Had some minor fit issues.

I assume all is well as voltage checks came back the same and it sounded good. Thanks for help!
 
Jun 7, 2020 at 10:44 AM Post #10,074 of 11,339

attmci

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I've had better day's! Here's why:


The Thomson 6080 is a personal favorite of mine. It's a clean, clear, airy, wonderful sounding tube that brought me a lot of joy! So I've recommended it to a few people.

Recently there's been various reports online (and offline) about the ones coming from sellers in Eastern Europe not functioning as they should.

Six of those found their way to me and i've had some fun with the testers today, checking them out.

They are supplied in HUGE boxes with some labels and a sticker on top. You could throw these of your local apartment building without anything happening to the tubes.

In the testers i couldn't detect any short or gas, so that's good. When required to supply any current at all, just about nothing happened.

In a transconductance tester where 7mA/V is the nominal NOS value, the best got up to 2mA/V.

Here's a picture of the line-up.



Luckily i had one good sample from my own collection to listen to!

Unfortunately, that one had sort of a bad interaction with my floor :frowning2: (hence, the bad day).



So it was dissected for the sake of curiosity.



Here's a view on one half:
- The coated heater wiring
- The cathode wherein the heater wiring lives
- The grid wire in nicely even spacing
- The anode plates with a large surface area for cooling
- All is suspended in a rigid mica construction seen on the previous image.



It's no Thomas Mayer picture quality (it's a phone!), but i hope you guys enjoyed it anyway!
Tom, who is selling these fake Thomson 6080 tubes? I am trying to collecting the names of entrusted ebay sellers, and please feel free to add your findings.

https://www.head-fi.org/threads/over-priced-tubes.920115/
 
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Jun 7, 2020 at 4:30 PM Post #10,075 of 11,339

PsilocybinCube

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Jun 7, 2020 at 5:49 PM Post #10,076 of 11,339

JTori

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A couple images I made this afternoon of my Crack-a-two-a with the TwoQuiet upgrade installed.

Best,

Joe.

Crackatwoa (1600).jpg


Crackatwoa (alone).jpg
 
Jun 8, 2020 at 11:16 AM Post #10,078 of 11,339

GreenNeedle

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Just thought I would join the Crack love in. Mine is still a WIP at the moment. I had originally planned on a Santos Rosewood base with polished chassis but I'm not so keen once I saw it in place. Love the base, not sure on the polished plate. In the pics below the plate is nearly fully polished. Still has a slight haze but I stopped when I had doubts.

The base is not finished yet. Still some Oil to add on with fine W&D to get the last remnants of saw marks off the sides. Feet still to be added.

The actual unit is fully wired and working but I may have to (quite likely will) have to unsolder a few wires to take the hardware off the plate. I have also bought a TKD 2CP-2511 to replace the stock pot.

So what I am thinking at the moment is for the plate to be a cream enamel like very old electronics used to have. Also to paint the sides of the transformer as it does have some sloppy resin marks all over using the same hammered black as the bell. Also want to paint the 12AU7 socket clamp with the same paint.

Will have a think over the week before deciding what to do and of course will hold off the speedball upgrade until it is all back together again.

These photos show the stock volume knob but I am changing that as well. lol.

IMG_4175.JPG

IMG_4176.JPG

IMG_4177.JPG

IMG_4178.JPG
 
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Jun 8, 2020 at 11:45 AM Post #10,079 of 11,339

JTori

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Just thought I would join the Crack love in. Mine is still a WIP at the moment. I had originally planned on a Santos Rosewood base with polished chassis but I'm not so keen once I saw it in place. Love the base, not sure on the polished plate. In the pics below the plate is nearly fully polished. Still has a slight haze but I stopped when I had doubts.

The base is not finished yet. Still some Oil to add on with fine W&D to get the last remnants of saw marks off the sides. Feet still to be added.

The actual unit is fully wired and working but I may have to (quite likely will) have to unsolder a few wires to take the hardware off the plate. I have also bought a TKD 2CP-2511 to replace the stock pot.

So what I am thinking at the moment is for the plate to be a cream enamel like very old electronics used to have. Also to paint the sides of the transformer as it does have some sloppy resin marks all over using the same hammered black as the bell. Also want to paint the 12AU7 socket clamp with the same paint.

Will have a think over the week before deciding what to do and of course will hold off the speedball upgrade until it is all back together again.

These photos show the stock volume knob but I am changing that as well. lol.

IMG_4175.JPG
IMG_4176.JPG
IMG_4177.JPG
IMG_4178.JPG

The rosewood base you've created is absolutely gorgeous! And I respect your deliberative approach to finishing out the Crack. It will be both audibly and aesthetically appealing. Making the amp yours is a big part of the build process, in my opinion. Can't wait to see it once it's completed.

Best,

Joe.
 
Jun 8, 2020 at 12:26 PM Post #10,080 of 11,339

DenverW

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Gotta agree there, that base looks absolutely amazing. If everything inside looks as good as outside then you're going to have one great little amp!
 

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