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Crack;Bottlehead OTL - Page 348

post #5206 of 8083

I didn't find a good solution. Long term, a high polished aluminium plate requires that you are very careful. When doing the mounting and soldering I was very very careful and worked pretty slowly with a blanket underneath. I treat my Crack with great care.

 

I used Autsol a couple of time during the sanding process, just to make sure that I wasn't missing any scratches from the coarser paper. For example, before going to 1200 from 800, I would give it a polish with Autosol just to make sure that the 800 paper successfully had removed any marks from the 600 grit paper and that the surface was even.

It can be wise to do this a few times, so you don't end up working your way to 2000, go into polishing and find a 800 grit scratch.

 

After 2000 I went over the plate about 2-3 times with Autosol, about 2*2 inches at a time (in circular motions).

 

Hope this helps.

post #5207 of 8083

The solution is a little expensive, though if you are investing that much labor it's probably worth it. You can get 2K urethane clear coat like they use on cars in a rattle can. It is really tough stuff, very glossy and very easy to apply. It's about $20 a can and once you break the inner seal to mix in the catalyst it only lasts for about 24 hours, so it's not like you can just keep the remainder of can on the shelf for another project. You can color sand and rub it out to a very high gloss. On a flat panel you could probably just flood coat it (i.e. one heavy coat) and rub it out and it would look great. You do have to wear an organic vapor type mask and some gloves when you spray it.

 

If that's too much $ a lot less durable but equally shiny looking finish can be made with clear lacquer.


Edited by Doc B. - 6/5/14 at 12:05pm
post #5208 of 8083
Quote:
Originally Posted by Lugnegaard View Post
 

I didn't find a good solution. Long term, a high polished aluminium plate requires that you are very careful. When doing the mounting and soldering I was very very careful and worked pretty slowly with a blanket underneath. I treat my Crack with great care.

 

I used Autsol a couple of time during the sanding process, just to make sure that I wasn't missing any scratches from the coarser paper. For example, before going to 1200 from 800, I would give it a polish with Autosol just to make sure that the 800 paper successfully had removed any marks from the 600 grit paper and that the surface was even.

It can be wise to do this a few times, so you don't end up working your way to 2000, go into polishing and find a 800 grit scratch.

 

After 2000 I went over the plate about 2-3 times with Autosol, about 2*2 inches at a time (in circular motions).

 

Hope this helps.


I have the same problem with the copper plate crack I built.  I can't touch the top plate or it leaves fingerprints which start to tarnish the copper.  The polish I'm using is supposed to have some silicone in it to prevent that kind of stuff, but it's not enough.

post #5209 of 8083
Quote:
Originally Posted by Lugnegaard View Post
 

I didn't find a good solution. Long term, a high polished aluminium plate requires that you are very careful. When doing the mounting and soldering I was very very careful and worked pretty slowly with a blanket underneath. I treat my Crack with great care.

 

I used Autsol a couple of time during the sanding process, just to make sure that I wasn't missing any scratches from the coarser paper. For example, before going to 1200 from 800, I would give it a polish with Autosol just to make sure that the 800 paper successfully had removed any marks from the 600 grit paper and that the surface was even.

It can be wise to do this a few times, so you don't end up working your way to 2000, go into polishing and find a 800 grit scratch.

 

After 2000 I went over the plate about 2-3 times with Autosol, about 2*2 inches at a time (in circular motions).

 

Hope this helps.

Thanks a lot, this info helps me a lot since I don't really have much experience with that kind of work, I guess I have some research to do before I do it on my crack.

 

Quote:
Originally Posted by Doc B. View Post
 

The solution is a little expensive, though if you are investing that much labor it's probably worth it. You can get 2K urethane clear coat like they use on cars in a rattle can. It is really tough stuff, very glossy and very easy to apply. It's about $20 a can and once you break the inner seal to mix in the catalyst it only lasts for about 24 hours, so it's not like you can just keep the remainder of can on the shelf for another project. You can color sand and rub it out to a very high gloss. On a flat panel you could probably just flood coat it (i.e. one heavy coat) and rub it out and it would look great. You do have to wear an organic vapor type mask and some gloves when you spray it.

 

If that's too much $ a lot less durable but equally shiny looking finish can be made with clear lacquer.

Thanks Doc, just to make sure I got it right, the 2k urethane clear coat is supposed to be sprayed just as a protective coat, after I got the wanted effect of chrome? I think i will give that a try I just hope I can find it in my country.

post #5210 of 8083

Just be aware of the fact that if you choose to polish you aluminium plate to a mirror finish and then spray it with a clear coat, some of that shininess will be lost. That's just how it works with aluminium and clearcoats. There's a ton to read about that very subject on car forums.

post #5211 of 8083

It does take away a bit of clarity, but how much depends a bit on how well you rub out the clear. If you don't put anything on the aluminum it will pick up fingerprints (practically from across the room!) and need to be polished frequently. On average it can end up looking worse than the clear coat. So it's a matter of deciding how much maintenance you want to do. After 20 years of dealing with them - polished, painted, powder coated, anodized, alodined, made from brass, copper, acrylic, you name it - you guys can probably see why I have chosen a low maintenance brushed finish for the stock panels.

 

If you want to try a third approach you can get the aluminum panel polished and then chromed. Just don't bend it and it will look pretty cool.

post #5212 of 8083

I was wondering, besides looks is any other reason the top plate should be aluminium? can it be glass ? wood? will it effect the amp itself somehow? 

post #5213 of 8083
It functions as a ground plane. So alternatives would best be another conductive material - copper, etc. You could try something else and I would guarantee that I absolutely can't guarantee how it would perform.
post #5214 of 8083

While my own polish jobs weren't quite as spiffy, I did protect them while working with some painter's tape. Removing a few tape smudges is much easier than trying to buff out scratches...

post #5215 of 8083

Thanks guys

post #5216 of 8083
Quote:
Originally Posted by Lugnegaard View Post
 

Are you talking about the wooden enclosure or chassi plate? I assume that you mean the plate. I've done it all by hand. Started with a 240 wet sanding paper and work my way through 320, 400, 600, 800, 1200, 1500 and finally 2000. Then I used a compound called Autosol for polishing and finally a wax for aluminium wheels. It took about 2-3 days.

Here's some pictures:

 

 

 

 

very nice ..thanks for the inspiration .I don't like to paint the top plate since naked aluminium provides good way to dissipate the heat . I will do similar plate on my Quickie once I receive it (it takes sooo long for the unit to arrive..) 


Edited by spacequeen7 - 6/6/14 at 11:00am
post #5217 of 8083

Question for the builders here, both the Octal and mini tube sockets seem to have a good bit of "give" to them when rolling tubes and in of the crack. Should this be the case? Is it possibly the retaining nut has come loose?

 

thanks...

post #5218 of 8083

Are you referring to the sockets in the amp and they are lose in the holes in the top plate or that actual tubes aren't fitting snugly in the sockets?  If it's the first one, you need to tighten the screws because they should be completely immobile.  If it's the latter, sounds like the little clips in sockets have bent from tube tolling.  You can bend them back (gently!).

post #5219 of 8083
I just got a RCA 6AS7G power tube and I get a (very slight) tinnitus like sound in the left channel. I tried different output tubes with same result. The tube was pretty cheap at 12$ + shipping. I probably won't get a flawless tube for that much money. Its very slight and I don't hear it when music plays but before I had zero noise and so it annoys me anyway. Any recommendations?
post #5220 of 8083
Quote:
Originally Posted by .Sup View Post

I just got a RCA 6AS7G power tube and I get a (very slight) tinnitus like sound in the left channel. I tried different output tubes with same result. The tube was pretty cheap at 12$ + shipping. I probably won't get a flawless tube for that much money. Its very slight and I don't hear it when music plays but before I had zero noise and so it annoys me anyway. Any recommendations?

Try cleaning the pins on the tube, it fixes noise issues surprisingly often. Most people will recommend an electrical contact cleaner such as Deoxit (it's worth it if you're going to be buying more tubes) but a high concentration rubbing alcohol or some fine steel wool could work in a pinch.


Edited by dante020 - 6/9/14 at 12:06pm
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