I have found that the cables from rca to the pot pickup a ton of noise in my case if they are near the psu. The idea of shielding them with some tape is something to keep in mind! Your build looks great!
I had that issue with the stock build signal braid. Swapped that out with a Mogami shielded cable and it fixed things. Although the copper tape over the cable may be making a small difference as well. I did the cree diodes, choke, PSU shield and, copper over the signal wire all at once so I have no idea how much each contributed (or not).
BTW, I had the same experience re: signal wire with the WHAMMY. Mogami mic cable ftw.
Ok good to know. But the first thing i do is to get my crack fixed and make sure it sounds right. Even with the crackling im still not sure if the bass performance should be like it is now. Maybe the replacement parts will fix it. I hope they will be here soon 
I have to say, that i actually had fun troubleshooting and handling a solderiron again.
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+1 on the HD600 on SB Crack. Last night, I just couldn’t quit it. The dreaded, one ore song. It felt that no matter how hard I turned the knob up, it sounded just as good, just as tight, just as musical, sublime… like it would scale to infinity. Talk about synergy.
The Border Patrol DAC plugged right into it. Maybe, just maybe that’s the only thing an audiophile truly “needs”. Anything more than this is simply just showing off. lol
I may decide to fiddle the the Crack a bit now, bought some copper shielding tape, and I’ll look into upgrading the pot and I’ll read up on the upgrading the caps. Not that I think it’s needed, but just because it’s probably cheap in the grand scheme of things and why not?
Genuinely a blissful listening experience.
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Funny, I’ve been thinking the same thing the last few days. I think HD600 + Crack is one of the head-fi pinnacles.
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I love my HD650 on the Crack. That being said, my DT 880, Aeolus and Atticus are awesome on the crack as well. 
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I just “finished” my build last night, which I got from the sale. Woke up this morning ready to give it more attention than just a couple of songs for testing. There are some touch-up cosmetic things I still need to do and speedball to be added later.
My changes over what was included as stock was using Kimber Cable TCSS 19awg wiring and Alps Rk27 100kax2 volume pot.
For solder, I had a tiny spool of cardas solder for a few months, and it was more than enough, and I liked it using it for this application.
The DT880 600ohm getting first listen. I used to have an HD 6XX, you guys are making think if I should reacquire a 6N0.
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Grab a 600 lol
For the Bottlehead Crack you can use the following for preamp tubes: 12AU7, ECC82 (EU designation for 12AU7), 7316, CV491, CV4003, 5814, 6189, 5963, 6680, 7730, B749 tubes.
According to Doc B at the Bottlehead Forums, the following tubes can be used IF YOU HAVE INSTALLED THE SPEEDBALL UPGRADE: E80CC/6085, ECC802s, 13D5, 12BH7 tubes. You could also use a 12AT7 tube, but the gain will be way too high and you’ll have almost no volume attenuation.
So I thought I’d do a quick post on the 17 tubes I own and have had listening time with.
RCA 12AU7A
This is what came stock with my BHC. This is often referred to as the RCA 12AU7A “Clear Top”. It is a very neutral and dynamic sounding tube. With the wrong power tube combination, it can become too solid state sounding. A little more in the low end would greatly improve this tube. It comes across competently, yet left me desiring more bass.
GE 5963
5963 tubes have very slightly less gain than 12AU7 tubes. This is a good thing as you have more volume attenuation range. I feel this is a nice affordable upgrade to the RCA 12AU7A that I received stock. It is similar to the RCA but a shade warmer with better Bass quantity and quality. The mids and treble are very similar to the RCA, as is the soundstage…which I’d consider average. These can go for as low as $10 to $20, which is a steal.
IEC/Mullard ECC82
You have to be very careful when buying NOS Mullard tubes. There are a lot of fakes, as well as different companies that Mullard either manufactured the tubes for, or slapped their name on. Also tube labels were being used very willy nilly. To my knowledge, IEC, Heath, EICO all had involvements with Mullard, with Mullard eventually purchasing IEC. Regardless, this tube is pretty darn good. Much warmer and thick sounding in the bass and mids. Soundstage is above average. My tube is from the late 1960s…supposedly the Mullard tubes from the Blackburn manufacturing plant from the 1950s and early 1960s sound better and are more desired.
Philips ECG JAN 5814A
This tube is similar to the RCA 12AU7A and GE 5963, but it has way better defined mids, better treble extension, and wider soundstage. These can go for as low as $10 and IMO are quite a steal at that price.
Tung-Sol JTL-6189 (12AU7WA)
This is an excellent sounding tube. It is a military spec 12AU7. This tube is one of the more linear of the ones I heard. Deep and controlled sub-bass, no bloom into the mids, and good treble extension with some air up top. These are also very affordable.
Ken-Rad 12AU7 (pewter plates, slanted horseshoe getter)
I bought this tube for $24 and was surprised how good it sounded. It does lack air up top, but it has excellent tonality in the mids and bass. A nice and pleasant sounding tube at an affordable price.
Raytheon CK6680 (6680 Tube)
This is almost exactly like the Ken-Rad both build wise and sound wise. They are around the same price, so not much to make it stand out against the Ken-Rad.
Matsushita 12AU7
This is one of my favorites. I never knew this until after buying the tube, but Mullard lent technology to Matsushita and helped them set-up their plant in Japan. Philips also assisted in providing materials to Matsushita. There is some magic in this tube. They are among the most dynamic of any I’ve heard. They have a really good balance of a clean and airy top end, excellent warmth in the mids, and accurate but punchy bass. They have a very wide soundstage, but it never sounds too wide where it becomes artificial sounding.
Brimar CV4003 (ECC82)
The CV4003 is a British Military Spec version of the ECC82. This one is very similar to the Matsushita, but has more air up top and a less wide soundstage, but better detail and very dynamic. It might have slightly less bass as well, but it is really too close to call.
Telefunken ECC82
The first thing that you notice is the open and airy treble. The bass is tight and punchy, but impactful. The soundstage is very wide and it has a great 3-D image. The mids have a tendency to sound clean and neutral. This is also the least microphonic of all of the tubes I own. This is a dynamic, wide and almost W sounding tube.
Northern Electric 12AU7
Honestly, not much to write home about. For a new production tube though, this is pretty good. Too solid state sounding for my preferences, and the $49 price is not worth it IMO.
Siemens E80CC (6085 Tube)
Very detailed, solid state sounding. Intimate soundstage but very dynamic. The bass hits low into the sub-bass…but the quantity may leave some wanting more. The mids are ruler flat sounding to my ears. The treble is definitely forward, but never encroaches on sounding fatiguing. Bright sounding for sure, but not in a bad way.
RCA 12BH7A
More impact in the sub-bass than a lot of cheaper 12AU7 tubes. The mids sound a bit recessed, which sort of turned me off. The treble has some grain to it, but still an affordable tube option. Soundstage is above average.
Marconi 12BH7
This is similar to the RCA 12BH7A, but has a wider soundstage and no recessed mids. No grain in the treble either, but there isn’t much extension at the very top end. Neutral yet engaging sound quality.
GE 5692 with 12AU7 to 6SN7 adapter
I personally am not a fan of 6SN7 tubes on the crack. There are a slew of people that do like them though. This tube in particular sounded wide and had a great sense of 3d to it. But it suffered from the mids being too withdrawn, the bass sounding “one note”, and the treble was grainy and brittle.
Tung-Sol 6CG7/6FQ7 with 12AU7 to 6CG7 adapter
This is the better sounding 6CG7 tube and it sounds very similar to the JTL-6189 I went over earlier, but with better and more impactful bass, as well as a wider soundstage.
Raytheon 6CG7/6FQ7 with 12AU7 to 6CG7 adapter
Not much to say about this. It was similar to the Tung-Sol 6CG7, but way more intimate and narrow of a soundstage. Has really good upper mids and treble detail, but it can be overwhelming with the wrong power tube.
Adapters
Just a few pictures of the previously mentioned adapters.
In closing, the Telefunken, Ken-Rad, Brimar and Matsushita are my personal top 4 favorites. The Brimar and Matsushita are probably my top 2.
Any questions, please just let me know! I’m here to help.
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Thanks, Hazi! This is totally tubular!
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Had picked up one of the Matsushita tubes a few days ago, looking forward to it now more! Not on your list but I’d been using these Syvania tubes I had from when I had the xDuoo T20. I like their sound, they were relatively cheap, curious if you’d run across them. I have a couple so use what you got right?
anyway, question for the brain trust since I’ve been wasting time online looking on beefing up the crack. No issues with my stock pot but my amp came with these (resistors? att filter?) in line and I’ve not seen them on other build just looking at pictures. Anyone know? They’re clearly not a need, what do they do?
Would have to see the circuit diagramm, but going of the Op-Amp based circuit that has been giving me a headache (unrelated to any hifi gear), those resistors would reduce input impedance and max volume.
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Really liking this tube lately. Our thoughts line up as well comparing it to the Mullard it’s much more lean and airy sounding and really smooth still so not coming across as analytical or anything.
Great rec 
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Best guess without a circuit diagram, provide an additional divider reducing the input level further, either to give more usable range on the pot or because someone was running a hot source.
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Only if you want to be happy. Otherwise definitely not lol.
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@MazeFrame is correct. I added those resistors to my build after being annoyed that I’m at full volume with barely any movement of the pot. In addition to giving you a bit more volume travel, this gets you out of the L/R non-linear region at the very begging of pot travel.
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Thanks for the response guys. Given that, might as well save myself the $ on switching it to an Alp. I’ll wait till it breaks then I’ll switch, how’s that?
But an Alps is only $15. Are you sure you don’t want to spend $15 
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believe me, It took me about two minutes of back and forth to hit the remove from cart button.