Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Tuco on August 28, 2024, 04:53:41 PM
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Was talking with a friend, telling him about having fun building audio components, and that despite my age, am still learn by screwing up - despite my experience similar equipment. He encouraged me to share my experience, because we learn more from failures and things that don’t work out as expected than we do our successes. So, here is your opportunity to grow wiser by learning from my mistakes and anyone else who might care to share their learning experiences. Feel free to contribute witty comments or your own lesser experiences. And, if you have actual experience with a technique or material that you have had success with, please contribute that too - good solutions are always welcome.
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Screw up number 1:
While I purchased some sexy black 4-40 button head screws for this build, I thought I’d try painting the heads of the larger screws. If you built plastic models as a kid, you probably recognize the Testors Enamel paint jar in the first photo below. Yup, that is the paint I used after chucking a screw in my cordless drill and sanding the head to give the paint a little tooth to hang on too. FYI, I used flat black because a flat sheen makes surface imperfections less noticeable that’s glassy sheen. While the screw heads might look pretty good in the second photo, that is after I touched them all up, because some of the paint chipped off when I used a screwdriver on them during installation. And, I’m confident it won’t take much to the chip paint off now either.
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Screw up number 2:
This one is all my fault. This is my second Bottlehead build. I finished a Bottlehead Moreplay a couple months a go and I am not totally satisfied with the finish on the chassis plate or the finish on wood base - I do love the Moreplay sound quality. So, I learned to powder coat and this Crack has a powder coated chassis plate and transformer end bell. But, I used Danish oil to finish the wood base for this build (again), and I am not really happy with the wood finish, again. I’d never used Alder and i find the natural wood is aesthetically pleasing. However, I don’t like a natural Danish oil finish on Alder for two reasons the finished grain is too dark and the sheen is uneven over large areas of dark grain. I should have bought and applied sealer and dead flat clear topcoat to keep that beautiful Adler natural wood look that I prefer. While this does not solve the color problem, I did learn that you can use a polish, like like the Howard Feed-N-Wax in the photo below, to even the sheen to a pleasant satin sheen over the entire surface of a piece finished with Danish oil. However, the satin sheen increases the grain contrast, which accentuates the dark colored grain that I don’t care for. Obviously, this is an aesthetic thing for me, and you might like a Danish oil finish, but I did this one to myself by using the same finish again - kind like knowingly buying a second Megadeath album when your a jazz lover.
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At least with the alder bases, you can just sand them down and start over if you aren't super happy with what you're seeing.
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I used to do a half a** french polish using shellac thinned with alcohol it looks nice but it is time consuming. I now use a couple of applications of boiled linseed oil and one or two coats of Johnsons furniture wax, does not overly darken the grain and is quick and easy peasy. Just one old mans opinion.
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At least with the alder bases, you can just sand them down and start over if you aren't super happy with what you're seeing.
That's what I did with my first Crack. Initially I didn't care about the look and built it for the sound. After a while I wanted it to also look good so stripped the paint, sanded it, and coated it with Watco Danish Oil. I also did other unnecessary modifications. Alder is actually very nice with oil.
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I also did other unnecessary modifications.
You changed the driver from Telefunken 12AU7 to a (what looks like) 6CG7? How did the sound change?
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Excellent! Never sanded an oil finish off, but I’m game - thanks for the suggestion!
Anyone find a paint that stick well to screw heads?
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I used to do a half a** french polish using shellac thinned with alcohol it looks nice but it is time consuming. I now use a couple of applications of boiled linseed oil and one or two coats of Johnsons furniture wax, does not overly darken the grain and is quick and easy peasy. Just one old mans opinion.
Had a friend that was an expert at applying and repairing of padded shellac. Got to watch him repair some 16th century French furniture over a couple week period and his work was amazing.
Boiled linseed and Johnson’s that is old school. Do you find linseed oil yellows and darkens less than Danish oil?
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Screw up number 3:
Despite my efforts to plan for everything, I always seem to miss a few things the first time through. One of the details I missed was the retainer for this tube socket - I would have like to have powder coated it.
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You can put the retainer on the bottom side of the chassis, and no the blo and wax stays nice.
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You changed the driver from Telefunken 12AU7 to a (what looks like) 6CG7? How did the sound change?
Actually that is a Channel Master 6SN7 with one of those garage adapters. I used a piece of black pipe for a guard over the bottom base to prevent electrocution.
I didn't have good luck with ANY 6SN7 I used ....... they all had varying degrees of hum. The 2 Cracks I currently use are configured to run:
1. E80CC
2. 12BH7A
I no longer using the 12AU7 (or 6SN7), although it is a great tube. I love the E80CC and the 12BH7A is just as good.
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The screws we supply are generally zinc plated steel and will take bluing pretty well, just remember to wax them or hit them with clear coat when you're done. (Or just buy black screws!)
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For quick and dirty I use a black Sharpie
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The screws we supply are generally zinc plated steel and will take bluing pretty well, just remember to wax them or hit them with clear coat when you're done. (Or just buy black screws!)
That is a good idea - thanks Paul. Out of curiosity, have you tried powder coating them?
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No, I haven't powder coated any screws. Rather than doing that, I stock black, brass, and zinc variants of what I generally use.
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You can put the retainer on the bottom side of the chassis
Hmm… this is one of those situations where you are used to seeing the tube base proud of the plate and now you’re left wondering if you’ll get used to it being recessed and like it better then…
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Roger that.
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Finished and tested the Crack last night. Haven’t plugged it into the main system with the better streamer and DAC yet, but sounded great on the inexpensive streamer and DAC that I tested it with. I’d never listened to music on a decent set of headphones and headphone amp before, so this is all new and a lot of fun. I’ll listen to it for a while then install the Speedball. Here are the completed Crack photos…
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Nicely done!
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When you install the small board of the speedball listen to that for a couple of weeks before installing the large board. I found I liked the sound with the small board and when I installed the large board I felt the charm was gone. I have a C2A and a Mainline so the crack is not used so much , so I think I'll remove the large board at some point in the future. YMMV.
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When you install the small board of the speedball listen to that for a couple of weeks before installing the large board. I found I liked the sound with the small board and when I installed the large board I felt the charm was gone. I have a C2A and a Mainline so the crack is not used so much , so I think I'll remove the large board at some point in the future. YMMV.
Thank you for the suggestion! I am going to try that.
Plugged the Crack into my Moreplay which has a much better source. The Crack with HD600s sounds super smooth, the bass is surprisingly good, and the highs are sweet - maybe a little rolled off. But that midrange, the midrange is superb. Old, crappy recordings sound the best I’ve ever heard them - Lightnin' Hopkins and old Jerry Jeff Walker never has sounded so good.
I have excellent loud speakers and a good neutral Class D power amp. And with the Crack and HD600s, I don’t hear the resolution, attack, and instrument decay that I hear with my loudspeaker speakers. Does Speedball really help with all that? One more question… with the Crack and HD600s, I don’t hear the 3D, holographic sound stage that I do with my speakers - it sounds like the music is being played in my head. Do you not get sound stage with headphones?
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The finished product is quite nice.
I built a crack and felt it was the 'tubby-ist' of the BH products that I have heard. Part of the charm, but undoubtedly different from that presented by solid-state gear.
I have the same observation about the way the music is experienced through headphones, and tend to prefer nearfield speaker systems for personal listening. There is an old thread for a reasonably simple circuit that mixes the channels and helps give the illusion of the music floating in front of the listener.
Karl
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The finished product is quite nice.
I built a crack and felt it was the 'tubby-ist' of the BH products that I have heard. Part of the charm, but undoubtedly different from that presented by solid-state gear.
I have the same observation about the way the music is experienced through headphones, and tend to prefer nearfield speaker systems for personal listening. There is an old thread for a reasonably simple circuit that mixes the channels and helps give the illusion of the music floating in front of the listener.
Karl
Thanks.
Regarding the preference for near field listening, I’ve found myself in that camp too and have decided to build open baffle speakers and servo subs designed by GR Research. They will probably be my end game speakers.
What fraction of your listening time do you listen with headphones?
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Jay,
I'd say less than 5%, probably the reason I didn't have any real grief parting with the Crack. My office system is on 8-9 hours daily, M-F and I generally have to move around the shop too much for headphones. The SEX amps, especially the one at home, allow me to scratch that infrequent itch.
Good luck with the OB build.
Karl
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I am not complaining… but, I find it odd somehow that the last few sets of tubes given to me or purchased by me have been handed over in a cigar box. This happened to you?