Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: beatcomber on July 31, 2021, 12:08:19 PM
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Hello all -
I just today completed my Crack build. All of the voltage tests checked out, the tubes and LEDs all lit up, etc. etc., so I was expecting glorious sound when I plugged in my headphones. What I got instead was barely audible, weak, thin sound from both channels with the volume pot maxxed out. :-[
These are the troubleshooting steps I've taken so far, all to no avail:
• Made a visual inspection and touched up a few questionable solder joints.
• Swapped in a known good 12AU7 tube.
• Compared my build to the image of the completed chassis in the instruction manual - everything looks correctly assembled.
• Went step-by-step through the entire manual to make sure I installed everything correctly - no mistakes found.
• Finally, as a last resort, I reflowed nearly every solder joint I could access, just to be on the safe side.
I'm at a loss here... What else I can check to try and narrow this down? Could it be something as simple as a bad power tube?
Thank you in advance...
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Could you post some build photos?
No, if your voltages are ok it's very unlikely that you have a dead tube.
What headphones are you using to test the amp?
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Could you post some build photos?
No, if your voltages are ok it's very unlikely that you have a dead tube.
What headphones are you using to test the amp?
I appreciate the response! Headphones are Sennheiser HD6xx (aka HD650).
I can't figure out how to post images here, it says I am not allowed to post external links.
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Let's try this: https: //postimg.cc/mhmZTjNN. (Copy/paste and remove the space after the colon.)
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At terminal 19, the lead poking through the inside of the terminal strip looks like it's touching the other diode leaving terminal 18. That needs to be trimmed.
The wire poking through B2 is somewhat close to B3 and should be bent around B2.
With the amp off, can you plug in your headphones and then give me a resistance reading between 12 and 6, as well as 12 and 10?
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At terminal 19, the lead poking through the inside of the terminal strip looks like it's touching the other diode leaving terminal 18. That needs to be trimmed.
The wire poking through B2 is somewhat close to B3 and should be bent around B2.
With the amp off, can you plug in your headphones and then give me a resistance reading between 12 and 6, as well as 12 and 10?
Thank you for taking the time to review my build.
Here are better views of the areas of concern:
https: //i.postimg.cc/pdtSkswk/IMG-7380.jpg
https: //i.postimg.cc/SK7vPWq4/IMG-7381.jpg
The resistance readings, with the headphones plugged in and the power off, are:
12 & 6 = .26
12 & 10 = 0
I went through all of the resistance readings, and all were within spec, except for the RCA jack center pins. Instead of getting 90k-115k, I couldn't get a reading at all. Maybe I've somehow shorted them? Here's a closer look: https: //i.postimg.cc/7PFYwk0L/IMG-7382.jpg
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Those resistance readings indicate that you've likely overheated the lugs on the headphone jack where the red and white wires land, and they have moved a bit under the spring tension of the contacts on the jack and are no longer working properly. We also see this sometimes from cheap 1/4" to 1/8" adapters that don't quite fit properly.
If you're not using an adapter, you'll need to replace the headphone jack.
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Those resistance readings indicate that you've likely overheated the lugs on the headphone jack where the red and white wires land, and they have moved a bit under the spring tension of the contacts on the jack and are no longer working properly. We also see this sometimes from cheap 1/4" to 1/8" adapters that don't quite fit properly.
If you're not using an adapter, you'll need to replace the headphone jack.
Thank you! There's an electronics store near me, so getting a replacement should be easy and quick.
Just to confirm... if the jack is indeed toast, it can still pass a little signal, correct? I'm asking because I can hear a little music playing.
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Maybe just a little. It's very, very, very unlikely that a general electronics store will carry the appropriate jack, so if you don't find one that completely identical, I would reach out for a replacement from us.
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Maybe just a little. It's very, very, very unlikely that a general electronics store will carry the appropriate jack, so if you don't find one that completely identical, I would reach out for a replacement from us.
Terrific, thanks so much.
Here in the Boston area, we are lucky to have a well-stocked electronics parts supply store (You-Do-It Electronics), and they have just about everything that online vendors like Mouser and Parts Express carry. I'm pretty sure I can get a proper replacement jack. :)
I will follow up tomorrow!
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https://www.mouser.com/ProductDetail/REAN/NYS212?qs=JfNPhaIww3JmEJtrIIVl%252Bw%3D%3D
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https://www.mouser.com/ProductDetail/REAN/NYS212?qs=JfNPhaIww3JmEJtrIIVl%252Bw%3D%3D
Much obliged!
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I just wanted to pop in quickly to say that I haven't had the chance to do any more troubleshooting - very busy at work this week - but will probably pick up a new headphone jack and fire up the soldering station on Thursday or Friday.
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Update...
As Paul correctly predicted, my local electronics supply store did not have the correct headphone jack, so I ordered a couple from Mouser, which cost about $10 including shipping. Kind of frustrating for a part that cost less than a buck.
I received the replacement and began the process of desoldering the old one, and ended up busting at least one of the 2.49k ohm 1/4 watt resistors. ($^@$%!!!) I went back to You-Do-It (You-Blew-It) Electronics, my local store, and they stock every resistor under the sun except for the one I need. The closest I saw in stock was (IIRC) 2.75k ohm or maybe 3k, I can't remember for sure.
If I order from Mouser, it will cost me another $10, which is outrageous. I plan to call Bottlehead HQ later today, and see if they will be willing to help me out.
Very frustrating, but there's not much else I can do...
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You could use a different resistor value there without ill consequences.
We do also provide replacement parts for a very reasonable cost.
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You could use a different resistor value there without ill consequences.
Great! I'll go buy the ones with the close value locally then, thank you!
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I think I'm all set to proceed. I just bought some 2.7k ohm 1/4-watt resistors, which I assume are suitable replacements.
Wish me luck!
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Yeah that's totally OK.
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Wonderful, I appreciate the response!
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Well, I've made one baby step forward, but it's still not there.
I just wired up the new headphone jack and resistors, and am getting great sound from the right channel only. The resistance reading from the right channel is within spec as well.
The left channel, however, is still dead. :(
Did I just fry another headphone jack? I'd wisely ordered an extra jack, so I can take another shot at it, but before I do, I'm hoping I can get some basic guidance on the proper soldering technique for connecting this part.
My soldering station is set to its max, 480 degrees F. I'm not sure if there is enough room for me to attach a hemostat (as a heat sink) on the terminal.
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I just re-watched the video on how to safely solder the power switch, so I suppose that is the same guidance I should use.
https://youtu.be/zjLO9ecjx7A
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480F isn't hot enough (480C would be). While it might melt the solder, it will take so long that you'll also melt the jack in the process.
I would get an iron that can get to at least 800F before trying again.
What iron are you using?
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480F isn't hot enough (480C would be). While it might melt the solder, it will take so long that you'll also melt the jack in the process.
I would get an iron that can get to at least 800F before trying again.
What iron are you using?
A ha, that makes sense!
This is what I'm using:
https://holife.com/products/holife-soldering-iron-station-60w-soldering-station-200-480-ae-adjustable-temperature-soldering-iron-set-with-separate-switch-solder-iron-holder-5-extra-iron-tips-brass-wire-ball-cleaning-sponge
I guess it's time to invest in a better (hotter) iron before proceeding.
THANK YOU.
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This should be arriving on Sunday. 8)
https://www.amazon.com/gp/product/B08NPPBSHH/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
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This is what I'm using:
https://holife.com/products/holife-soldering-iron-station-60w-soldering-station-200-480-ae-adjustable-temperature-soldering-iron-set-with-separate-switch-solder-iron-holder-5-extra-iron-tips-brass-wire-ball-cleaning-sponge
That iron reports temperature in degrees C. If you had it set at 480 C, that's quite warm. The soldering station that you'll get on Sunday has the same temperature range as your current soldering station, so you could continue working now, as long as you convert the temperature from C to F so you know what you are doing. (It looks like your new station will convert the temperature to F for you.)
Mary
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If that is the case, 480C is plenty hot.
If you plug in your headphones and you still see a zero ohm reading at terminal 6 or 10, then you need to turn up the heat all the way on the station (if it isn't up already) and spend a bit less time soldering it on.
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I solder at 650F 99% of the time. Set your station to 340C and you should be good to go.
But as always YMMV.
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By golly, you’re right! 480c = 896f.
I guess what it comes down to is I have to work on my technique. I’ll do some practicing on the fried jack before attempting it again on my last good jack.
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I solder at 650F 99% of the time. Set your station to 340C and you should be good to go.
But as always YMMV.
If that is the case, 480C is plenty hot.
If you plug in your headphones and you still see a zero ohm reading at terminal 6 or 10, then you need to turn up the heat all the way on the station (if it isn't up already) and spend a bit less time soldering it on.
Am I better off going full blast (896f) or should I dial it back to 650f?
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I would recommend full blast and not a ton of solder. Just enough to fill in between the wires and headphone jack. Use just enough heat for the solder to flow out between the parts.
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I would recommend full blast and not a ton of solder. Just enough to fill in between the wires and headphone jack. Use just enough heat for the solder to flow out between the parts.
Terrific, that’s the kind of direction I was hoping for!
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I just fried a THIRD headphone jack.
I am at my wit's end now. To get all the way through the entire build to be thwarted at the very last stage is frustrating to say the least. Clearly my soldering technique is not good enough to work on these delicate headphone jacks.
What are my options here? Do I have to keep throwing money at Mouser in the hope that one of my installation attempts will work, or do I have to pay Bottlehead $125 to solder this one part for me? :(
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A mistake that I made several times while soldering jacks and other easy to destroy parts is applying too much pressure with the iron. I puddle a little solder on the joint right away to facilitate heat transfer, and then a little more to flow, but don't lean on the joint. Barely touching.
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Post some pictures. Maybe you’re assuming it’s the headphone jack and it’s actually a problem elsewhere in the build
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A mistake that I made several times while soldering jacks and other easy to destroy parts is applying too much pressure with the iron. I puddle a little solder on the joint right away to facilitate heat transfer, and then a little more to flow, but don't lean on the joint. Barely touching.
I don't think that was the problem, I tread very gingerly on the last attempt, but who knows?
Post some pictures. Maybe you’re assuming it’s the headphone jack and it’s actually a problem elsewhere in the build
Good idea, will do shortly.
Thank you.
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Have you measure the resistance at terminals 10 and 6 with headphones plugged in every time you've wired in a jack?
You could have two problems, so if you just kept soldering in jacks and trying to use the amp without doing the resistance checks, then you may be chasing your tail a bit.
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Have you measure the resistance at terminals 10 and 6 with headphones plugged in every time you've wired in a jack?
You could have two problems, so if you just kept soldering in jacks and trying to use the amp without doing the resistance checks, then you may be chasing your tail a bit.
Resistance at 10 & 6 is .606k ohms.
Resistance at 12 & 6 is .272 ohms.
Resistance at 12 & 10 is .303 ohms.
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Here's a view of my latest attempt to solder the jack. (Yes, I know there's a blob on the upper left terminal. My soldering technique is clearly lacking.)
https://i.postimg.cc/BnQxtHZb/IMG-7483.jpg
https://i.postimg.cc/4yGQ40FH/IMG-7484.jpg
https://i.postimg.cc/2ydT4YBx/IMG-7485.jpg
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Hey, what kind of solder are you using? 60/40 or 63/37 rosin core is what you want.
You need to bend the leads around the terminal. I see at least two terminals that are not securely soldered and will not carry the signal to the headphone jack. The jack does not look fried, I would de solder and redo the connections bending the wire and resistors to make a good physical connection and a place for solder to flow into.
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Hey, what kind of solder are you using? 60/40 or 63/37 rosin core is what you want.
You need to bend the leads around the terminal. I see at least two terminals that are not securely soldered and will not carry the signal to the headphone jack. The jack does not look fried, I would de solder and redo the connections bending the wire and resistors to make a good physical connection and a place for solder to flow into.
I'm using 60/40 solder.
I just tried reflowing the solder and securing the connections, to no avail. FWIW, I don't see any plastic melted on the jack, so I wonder if that is indeed the problem?
I appreciate all of the helpful responses, but I really feel like I'm spinning my wheels here. I don't know what more I can do. I need to walk away from this project for a little while because I'm getting too frustrated.
I built a Fender Champ kit last year, and it went off without a hitch. I thought this was going to be comparatively easy.
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He’s saying more than to reflow. Most of those connections are not properly crimped and making good connections before you even need to worry about solder. There isn’t enough solder. Don’t go nuts using too much solder, but that middle lug on the right especially could use some more.
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It looks like the solder has balled up on the joint but not flowed. The wire and terminal should be hot enough so that the solder flows onto the joint without the solder touching the iron. It should leave a concave meniscus, with the solder trying to creep along the metal surfaces.
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Yeah, you must place the tip of your iron on the terminal and the wire simultaneously so they come up to temperature BEFORE adding solder. Perhaps count to 5 before adding solder. As I stated earlier I set my iron to 650f, if you use an 800f or more you can cut the time down.
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This is helpful advice, which along with the encouragement, is greatly appreciated. I’ll give it another shot!
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Resistance at 12 & 6 is .272 ohms.
Resistance at 12 & 10 is .303 ohms.
Those are resistances that I would expect with an OK headphone jack *if* that is 272 and 303 ohms, or 0.272K ohms and 0.303K ohms.
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Those are resistances that I would expect with an OK headphone jack *if* that is 272 and 303 ohms, or 0.272K ohms and 0.303K ohms.
Oops, yes, those numbers are in k’s!
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Some things I just wanted to mention in case it offers any clues, before I dive into this again...
• I am getting NO resistance reading from the positive (center pin) terminals on the RCAs.
• While my soldering of the headphone jack might not be great, I AM getting continuity readings at all of the junctions.
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Can you post some updated build photos?
If you turn the pot all the way up, do you get a resistance reading from each center lug on the volume pot?
When you say "no reading", do you mean 0 ohms, or over limit?
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Can you post some updated build photos?
I have done any additional work since Sunday morning...
If you turn the pot all the way up, do you get a resistance reading from each center lug on the volume pot?
When you say "no reading", do you mean 0 ohms, or over limit?
This is what the meter reads... no difference from when the probes are not making contact.
https://i.postimg.cc/nzm0SDqt/IMG-7490.jpg
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I think I see the potential problem. On your volume pot if you look at the upper outer lug where the white wire connects, there's a bunch of solder that has flowed down and along the flat metal bit on the pot, and this solder will flow into the pot and destroy it.
When you solder these connections, crimp the wire on the pot and just put in enough solder to fill in between the crimped wire and the pot lug. You don't want to use much more than that because it can go places you don't want it to!
You'll definitely need to replace the pot, this isn't something that's fixable.
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If you have your meter set to ohms and you probe the center pin of the rca jack and put the other probe on the center pin of the vol control and you get the same reading as if your probes were not touching you have no continuity between the center pin of the rca jack and the center pin of the VC. Either you have a poor solder joint or the wire is broken possibly under the insulation.
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If you have your meter set to ohms and you probe the center pin of the rca jack and put the other probe on the center pin of the vol control and you get the same reading as if your probes were not touching you have no continuity between the center pin of the rca jack and the center pin of the VC. Either you have a poor solder joint or the wire is broken possibly under the insulation.
Now I'm really confused...
The center pins on the volume control are indeed showing no continuity with the center pins on the input jacks.
I also checked for continuity between the red and white wires on the center pins of the VC and their corresponding pins on the 12AU7 socket, and there is continuity there.
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I think I see the potential problem. On your volume pot if you look at the upper outer lug where the white wire connects, there's a bunch of solder that has flowed down and along the flat metal bit on the pot, and this solder will flow into the pot and destroy it.
When you solder these connections, crimp the wire on the pot and just put in enough solder to fill in between the crimped wire and the pot lug. You don't want to use much more than that because it can go places you don't want it to!
You'll definitely need to replace the pot, this isn't something that's fixable.
A ha! Hopefully I can source the volume pot locally. I assume it's a fairly common part.
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Yes, 100K dual log. RV24BF-10-15R1-A100K-LA is the part we use. Be sure you at least get a dual log pot with solder lugs if you are looking at other options.
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Now you can probe between the rca center pin and the vc pin that is to the left of the center pin, this the wire that goes to the rca jack..
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I destroyed my original volume potentiometer by using too much solder. After I replaced my pot, my Crack went back to working normally. I also got bit by the modding bug after replacing my stock pot haha.
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Now you can probe between the rca center pin and the vc pin that is to the left of the center pin, this the wire that goes to the rca jack..
Those connections have continuity.
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I destroyed my original volume potentiometer by using too much solder. After I replaced my pot, my Crack went back to working normally. I also got bit by the modding bug after replacing my stock pot haha.
I'm certainly no expert, but my spidey sense is telling me that this is the cause of the problem. Fingers crossed!
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SUCCESS!!!!!
I just carefully wired up the replacement pot, making sure to not overdo it, and it's working beautifully now!!!! There's no hum, hiss, or noise either, thank gawd.
A huge THANK YOU to everyone who offered guidance, suggestions, and encouragement, with a special word of thanks to Paul Birkeland. There is no way I could have carried this through to completion without the kind assistance of this forum!
https://i.postimg.cc/mZKGm6JS/IMG-7575-2.jpg
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It looks great!
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It looks great!
Many thanks, sir! It turned out to be everything I had hoped it would be. My HD-6xx's have never sounded so good before!
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Nice looking amp.
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Nice looking amp.
Many thanks, Doc! Despite the setbacks, I immensely enjoyed building it.
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Is it just me that follows these threads like a Netflix boxset?
Have been checking in regularly for latest instalment and so pleased to see a happy ending!
Nice job and way to go for persevering.
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Same here! I love watching people figure things out on their way to building stuff. It's just wonderful.
Mary
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Same here! I love watching people figure things out on their way to building stuff. It's just wonderful.
Mary
Is it just me that follows these threads like a Netflix boxset?
Have been checking in regularly for latest instalment and so pleased to see a happy ending!
Nice job and way to go for persevering.
Thank you for the kind words. I have found the friendly and prompt support provided on this forum invaluable!
I continue to be delighted by the Crack. It really is everything that I've been led to expect, if not more. As an added plus, for a relative beginner like me, there is the pride of knowing that you built it yourself.
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"...there is the pride of knowing that you built it yourself."
The kits are like it's namesake...you did a fine job with this one, cant wait to see what your next build looks like.
Karl
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"...there is the pride of knowing that you built it yourself."
The kits are like it's namesake...you did a fine job with this one, cant wait to see what your next build looks like.
Karl
Thanks, Karl! :)
I even made a custom label to put inside the case, matching the font used by Bottlehead in the instructions manual:
https://i.postimg.cc/4NLyLCZJ/IMG-7597.jpg