Luxembourg Crack

grausch

New member
Dear All,

I finally completed my Crack this weekend and wanted to share some pictures of the final product. I am a complete DIY newbie and have not done any woodwork nor soldering before.

I initially received my kit in November 2013 and immediately glued the base and then set about sanding and staining it. My choice of stain was very much inspired by Clark Blumenstein's work on his chocolate Bamboo Orcas, but unfortunately it is impossible to get Tried and True varnish in Europe. I settled on an Interior Wood Stain from a German company called biopin. It seemed to be the most natural product I could find over here. After applying the first coat, and while it was still wet, I seriously considered ordering a base from Clark B. Luckily the colour of the dried stain looks much better than the colour of the wet stain. I have not applied a clear varnish, and am not sure if it is necessary, but I am very pleased with how the base turned out.

The only other cosmetic change I did was painting the transformer bell. Removed the coating as recommended by Doc B and painted two or three layers of black Hammerite paint. It was definitely not the best job I could have done, but unless you look really closely, it looks pretty good. I assembled the rest of the chassis of then set about purchasing the rest of the equipment I would need.

I paid a small fortune to get my Ideal Stripmaster Lite, but luckily everything else was available locally.  Once I had everything, I guess I doubted whether I could actually complete the kit. Left it for a couple of months and finally decided to man up this weekend. Watched the beginning of Tyll Hertsens' review of the Crack, saw him attach and solder a joint or two, measured and cut some wires (generally cut about 5 in advance) and started soldering. Halfway through the build I realised that my solder joints were looking much better than the initial attempts and I reheated and touched up all of the existing solder joints.

I made one mistake with the rectifiers by placing them one terminal slot down. Luckily I noticed it with the third rectifier, but I had already soldered the first two. Spoke a few choice swear words, got out the desoldering braid, heated it up and promptly burnt my fingers.  :o Watched the rest of Tyll's review and noticed that he had advised holding the braid a fair distance away from the soldering iron. Struggled a little until I realised I could remove the rectifiers while the solder was hot and then remove the excess solder with the braid.

The rest of the process went quite smoothly and it took me about 8 or 9 hours in total to complete the soldering section of the build. All my resistance checks worked and now I am just waiting on the alligator clips and RCA cables to arrive. Should be here this week, then I can do the voltage checks and finally test this baby out!

Some other notes on the build itself:
1. I managed to install the power switch the wrong way, but luckily adjusting for that was quite easy.
2. At some point I decided to ensure that all the terminal holes were completely filled with solder. In hindsight that may not have been the best idea, as a) I do not think it is necessary, b) if I decide to install the Speedball upgrade there is more solder to remove and c) I still need to remove some blobs of solder from the terminal strips on the power transformer. Luckily everything is still on the metal, but that needs to be cleaned up.
3. I did not strip enough of the insulation of the wire initially and I ended melting the insulation of some of the wires.
4. I nicked some of the insulation and capacitors with the hot soldering iron by being a little careless. I doubt it did permanent damage to the capacitors, but the soldering iron now looks much more used. However, I am a little annoyed at the cosmetic damage that caused to my build.
5. I should have watched how Tyll soldered the RCA sockets before attempting it myself. Don't know if I caused any damage there or if there are any air bubbles in those joints.

As you can probably tell, I am quite proud of my first DIY attempt and can't wait to start listening to some blues.

I have to thank the Bottlehead team for their kit and the excellent manual.

Kind regards,

Gunter

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Great job Gunter!

Looks beautiful.

Every build you will learn lessons.  Sounds like you learnt some stuff.

Enjoy your listening sessions!  I wonder how long you will leave it stock?

Take care...Dave
 
grausch said:
3. I did not strip enough of the insulation of the wire initially and I ended melting the insulation of some of the wires.

This actually tends to be a problem more with where you are applying the heat from your soldering iron.  If you have a wire wrapped around a terminal, and the wire jacket is tending to melt before the solder flows well, consider trying to only heat the terminal, then let the solder flow around the wire and heat it up.

Stripping more than the general 1/4" (6mm) may lead to shorts and functionality issues in your Crack, and tends to be a common issue in the repairs I see.

That wood base looks great!

-PB
 
Great to hear your up and running, I  also found as a newbie that getting started was actually quiet daunting this is probably a good thing for those of us with little experience as it meant for me there was a lot of double and triple checking of each step. The Tyll Hertsens build video helped immensely and I would often pause to replay it for reference during the build. I doubt I would have purchased the Crack kit had it not been for his video.
 
 
@dave: Thanks, the base turned out exactly how I wanted it. The flash did make it a little brighter but the colour is very close to those of the chocolate orcas under normal lighting. I definitely learnt a lot and if I build a second one now, it would definitely turn out better. I am planning on leaving it stock for now and just enjoy it as is for a couple of months. Am planning on buying some Orcas, maybe adding a Dungeness (will see how the Orcas sound first) and then building a Stereomour for them.

@Paul: Thanks. Regarding the insulation, I stripped with them a Stripmaster and was eye-balling the length. Initially I probably only stripped 4-5mm, but did not consider it an issue as I could still attach the wires everywhere. I had one mishap on B8L (not sure as I don't have the Crack at work), where a little of the insulation got melted onto the terminal. I usually heated the wire on the opposite side of the terminal and fed the solder from the insulated side. I think the melting was caused by rosin (brown stuff that evaporated later) running down the wire and reaching the insulation. Later on I stripped them at a more consistent 6 mm and that definitely helped. Should have been more clear on that in my post. Perhaps if I only heated the terminal it would also have solved the issue.

@Jamie: Yes, the video definitely helped. I should have watched it from beginning to end before starting, but I was just way too impatient. We should also not underestimate the quality of the manual. A lot of thought went into producing it and I would have been thoroughly lost without it.
 
Ok, received my RCA cables this weekend, but still waiting on the alligator clips for the voltage checks.

Again, way too impatient and decided to see how it sounds. Running from the headphone out of my iPhone 5 to the Crack to my 250 Ohm Beyerdynamic DT 770 Pros. The wife is of the opinion that I have not smiled that big in ages. I can only say that I really enjoy the sound.

In any case, I was running the iPhone on full volume and the Crack on about 10-20% of its full volume. I have had it up to about 75% and it still sounds great, but I don't really wish to damage my hearing this way. So I decided to add in the 2 270k resistors as mentioned in the FAQ thread. First I did the soft-start mod, which I then tested and since the amp was still working I added in the 2 270k (0.25W carbon) resistors and tested it again.

This time round, even at full volume, there was no sound and I thought I must have damaged the input jack somehow. Had a look at the amp, but could see no damage in that area and all solder joints looked good. Decided to test it again, noticed that the iPhone was only at about 70%, so I upped it to 100%, and this time there was some volume with the amp at 100%. At full volume with the resistors in, the Crack was not as loud as 20% volume without the 2 resistors. So I removed the 2 resistors and am currently quite happy with the Crack.

PB: If you don't mind, why did I experience such a huge drop in volume? I assume I can use resistors that have a lower resistance and then get less of a decrease in volume. Also, what would happen if I use resistors with a higher wattage, for example using a 150k 1W resistor?

Cheers,

Gunter
 
grausch said:
PB: If you don't mind, why did I experience such a huge drop in volume? I assume I can use resistors that have a lower resistance and then get less of a decrease in volume. Also, what would happen if I use resistors with a higher wattage, for example using a 150k 1W resistor?

270K resistors are about an 11dB pad, which is significant.  Lower resistance will give you less padding.

A 150K 1W resistor will have identical padding to a 150K 1/16W resistor.  The only difference will be that the 1W resistor will be more difficult to install because it is larger and its leads much thicker.

-PB
 
Thank you, that makes sense. I also reread the Crack FAQ and it turns out I had my resistors on the white and red wires of my headphone output and not the RCA jacks. I am assuming that the resistors were in series which would mean that I had added a total resistance of 540k to the circuit and probably had a damping of 22 db.

However, I assume I am missing something here, because it would be a lot easier to just add 1 resistor to the headphone output rather than the 2 on the RCA jacks. Is there a specific reason why we would pad the input to the amp, rather than the output as I did?

Cheers,

Gunter
 
grausch said:
Is there a specific reason why we would pad the input to the amp, rather than the output as I did?
If you add resistors to the output, you will drastically increase the output impedance, which will lead to poor bass control and potentially a lot of distortion.

 
Not happy to leave things as they were, the urge to tinker bit me quite a bit. Over the last couple of weeks, quite a bit of work was done to the Luxembourg Crack, and I learnt even more by not having the excellent manual telling me exactly what to do. However, I still found myself referring back to it with almost every upgrade.

Firstly, I had read good things about the VA Labs attentuator and decided my Crack should get one. Since I can decrease the volume on my source, channel imbalance was never an issue. I found the stock pot to be quite good, and can't really say whether there is any difference in sound. Theoretically there could be, but I am not able to tell the difference since the install itself took probably an hour or two. Since I wanted to redo the braiding, and the attentuator is taller that the stock pot, I needed some additional white wire which I requested, together with some missing parts on the Stereomour. All the parts got sent same day that I requested them. Really great service from Eileen and the crew.

The wife then redid the braiding and did a much better job than I can. I also used the opportunity to move some of the wires at the 9-pin socket. I had crowded it too much during my build and would have run into problems trying to get the Speedball stand-off in there. Should just have routed them as per the manual and not tried to be smart. I then ran into some issues due to the start-voltage mod, but luckily the Bottlehead crew helped resolve this. http://bottlehead.com/smf/index.php?topic=6857.0.

Part of the problem above, was that the switch on the headphone jack on my right channel was disengaged even with no headphones inserted. PB advised that I use a Switchcraft stereo jack that I believe is a guitar jack. I was a little hesitant at first because the wiring would be pretty tight. However, at 7 Euros for the jack, I decided I had nothing to lose. Installed the new jack and needed some additional wire length on all of the connections. Luckily I had plenty of black left over from my Stereomour build, but red and white were running a little short. Used some of the braided wire I replaced earlier and it is visibly crinkled, but I am fine with that. My first solder joint on this created a solder bridge and I needed to fix this. Everything is very tight in there.

The Switchcraft is definitely better quality, but I think the standard jack is quite good. Downsides to the Switchcraft are its size, the difficulty in soldering the wires (everything is very close and there are no proper lugs), the wire sheath (also used as ground) is quite bendable and I lose the switch (start-up voltage mod, but I don't think it is necessary anymore). The standard jack is much easier to solder on, the resistors are neatly tucked away inside, and it won't catch on anything. I don't know if I would recommend this to others, but I am not replacing mine. I can't tell if there is a sonic difference, but I like the general look and sturdy feel.

Last upgrade was the RCA jacks. Of the six I received for the Stereomour, 2 are quite loose and I think the thread is either stripped or the nut does not have enough thread. Since I was ordering parts, I just got some of extra RCA jacks for the Crack. I got the REAN / Neutrik ones recommended by mcandmar on this thread http://bottlehead.com/smf/index.php?topic=6707.0. At 1.47 EUR each, these are definitely worth it. I have not compared the Crack and Stereomour RCA jacks yet, but I feel the ones I received with the Crack are much more sturdy. However, the new jacks are really great quality. Really solidly built, a real step up from the old ones and an absolute steal for the price.

In between, all of this, I also sanded the base (80 grit / 120 grit / 240 grit) as I was not quite happy with some of the brush marks visible. Both outside and inside got sanded and a 75% cold pressed linseed oil / 25% biopin mix was applied. Currently there are 2 layers on the outside and 1 layer inside. I still need to remove some of the 80 grit scratches on the inside and then it will get another layer.

Not sure if it was the aggressive sanding, or the prior application of the biopin stain / varnish / all-in-one, but the base really absorbed the current mix extremely well. The grain popped more than ever and I absolutely love the colour. The base will still get a 50/50 mix, and 25/75 mix and maybe a 100% biopin mix, will see how it evolves. Since it is dark when I get home in winter here, I only sand the base on Saturdays and leave the coat to dry for a week. So this process will take couple more weeks to finish. The Stereomour was only sanded with 240 grit, and that base did not take the mix nearly as well. Once the Crack is done, that base will need some more attention.

Lastly, after installing the Switchcraft jack, I redid my resistance checks. The attentuator is at 0, i.e. no volume, and everything checks out fine, except for the right RCA jack to ground. It should read 100 kOhms, but only reads 50 kOhms. It definitely measured correctly after I initially installed it. I have isolated it to the attentuator since the input to output reads 50 kOhms. However, I have no volume on the right channel when volume is turned all the way down. Shouldn't there be music playing if the resistance is only 50 kOhms? The other steps all measure correctly but this one is wonky. I am baffled that I am hearing no sound when I should be hearing something. I mean a jump from a 50 kOhms resistance to ~99 kOhms (first step of volume up) should lead to a decrease in volume and not an increase. Also have no channel imbalance whatsoever. Other than the resistance reading being wrong, there is no sign that anything is wrong!

If someone has any ideas as to why the above would happen, I would be very grateful. Very curious to know what is going on.

Enough of all the writing, since this is the gallery forum, here are the latest pics...

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That's a really nice build! One thing caught my eye is that you have replaced the headphone jack on your Crack and it is not the usual culprit (Neutrik locking jack). I wonder how it works mechanically?

I did get the Neutrik jack but hesitate to put it in because it seems to require quite a big force to insert and remove the plug. I am still looking for something smoother and require less insertion and removal force...
 
hwaitung, thanks for the kind words. It's been a labour of love, but looking at your build I guess you know exactly what I mean. It also looks like we have the same RCA jacks. Still some work to do on the 9-pin, 8-pin and transformer wiring. With my soldering skills having become much better, I can do a better job. Not that anything is amiss, it's just fixing melted insulation. Will start that process when I finally order the Speedball.

Regarding the jack, the stock jack works great and soldering on it is pretty easy. I believe it is a Neutrik jack as well. There are some upgraded versions available, although not all of the come with solder lugs. If you are comfortable wrapping wire around PCB pins and soldering them, you can get a gold plated jacks that look exactly like the stock jack.

I had considered the locking jack, but did not like the soldering options there. It just looked very cramped compared to the stock jack. Ironic then that the jack I installed also was very cramped. PB recommended it at the linked thread and I wanted to give it a go. I believe it is a guitar jack, it is stereo (there a lot of mono jacks out there), it comes with no instruction / schematic and I needed to reference to the standard jack to figure out how to wire it (using the headphone plug to see where L,R & G were). It is very cramped in there, so take that into account. Ground has no solder lugs, so you need to wrap the ground wires and the resistors to the wire sheath. I wrapped them all at the same spot, but needed to do this one-by-one and solder each one just to keep everything in place. Once everything was in place the entire joint got resoldered.

First time I plugged in headphones it was very tight. It has since loosened a bit, but still holds the plug tightly. It is definitely smooth and does not require excessive force.

If you are uncomfortable with the force required for the locking jack, you could consider getting a right-angle adapter. I have one plugged into my amp permanently and use that to plug my headphones into. It reduces tension on my headphone cable and reduces wear on the jack.
 
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