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Aluminum plate thickness for amp project

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Posted on June 4, 2015 at 06:30:42
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Hello,

I am starting to pull together my first amp project, and need to figure out the thickness of the aluminum plate that the components will sit on. My layout looks like it will be 20 x 14. The idea is to have a wooden frame that is rabbited out by 1/4 to support the loaded plate, as well as angle stock screwed to the plate and frame from below to fix the plate in place and provide additional support. I don't have a scale, but the input transformers and power transformers weigh in at about 60 lbs (they are big monsters), and will be located towards the rear edge of the plate (about 1" in from the edge).

I was thinking of 1/4" just to be on the safe side, but maybe that is overkill or inadequate - I have no experience. I was looking for a load table on the web, but only found one for aluminum flooring.....

Any input of suggestions would be appreciated. I am just getting started on rounding up remaining components for the project and getting my brain wrapped around the schematic. I will certainly be back often with lots of questions once I get into this.

Regards -- Roger

 

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RE: Aluminum plate thickness for amp project, posted on June 4, 2015 at 06:42:58
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 One quarter of an inch is perhaps overkill. One eighth inch Aluminum, with an occasional brace, always worked for me.

BTW, I now use steel, either 12 or 14 gauge as the maximum or minimum, and I have the steel supply company, for a nominal fee, brake ( bend at 90 degrees ) the chassis, and have a friend weld the corners. This gives great strength and better shielding. Plus, the entire chassis can be powder coated, once I put in the holes for tube sockets and component mounting. Powder coating is way way COOL !!!

Wood sides are amateurish, not strong enough at the 90 degree joint.

Jeff Medwin

 

+1 for 1/8", posted on June 4, 2015 at 07:52:55
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004
 I find 1/8 inch to work well, 1/4 would be overkill. 1/8 is also about the thickest you can use if you're planning to mount your tube sockets from the under side. You can reinforce the top plate using aluminum 'C' channel bolted underneath if necessary to eliminate any flex caused by heavy transformers.

I can't second Jeff's enthusiasm for steel chassis, though. Difficult to work with unless you're a machinist/welder, and its shielding benefits are marginal if you've wired your amp correctly. I've done both, and only use aluminum these days. If shielding is required, use it locally, no need to shield the whole chassis.

Just my 2 cents.

 

RE: +1 for 1/8", posted on June 4, 2015 at 07:58:07
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 The steel supply company that has the sheet steel, usually will also have a plasma cutter, and a brake capability, so I pay them for those services, and its a breeze !!

 

Some suggestions, posted on June 4, 2015 at 08:18:00
caffeinator
Audiophile

Posts: 1729
Location: Pacific Northwest
Joined: August 22, 2003
 Hi rogerh113,

I have built a chassis almost exactly as you've described, with a very similar complement of iron sitting near the back edge. The top plate was made from 0.125" aluminum, and there's no sag at all. Had I noted any deflection, I'd have used bracing below as opposed to increasing thickness. Quarter-inch material is way overkill, imho.

I have also built chassis from steel, and it is harder to cut than most aluminum, though, depending on what sort of cuts you have to make (like lots of circular holes), this may not be such a big deal.

I've had good luck with FrontPanelExpress (no affiliation) to cut top plates and other details in aluminum. They can also provide pieces to make a complete (box) chassis, but this gets more costly than wood.

A hybrid approach I've used, where a complete metal enclosure was desired, was to get an aluminum top plate from FPE, sized and configured to fit a Hammond prefab steel box.

 

RE: Some suggestions, posted on June 4, 2015 at 08:41:27
SteveBrown
Audiophile

Posts: 2454
Location: Portland, OR
Joined: November 14, 2002
 I assume when you put this on a Hammond box you use the box upside down as a bottom with an open top that the aluminum plate goes on top of?

 

RE: Aluminum plate thickness for amp project, posted on June 4, 2015 at 09:43:19
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 Are you doing the machining yourself?

1/8" sounds reasonable, and if you are building the wood frame and laying everything out, you could run a wood support down the center of the amp to split it into two 10"x14" sections, which would certainly be fine.

Steel and aluminum both offer shielding.

 

RE: Some suggestions, posted on June 4, 2015 at 10:24:24
caffeinator
Audiophile

Posts: 1729
Location: Pacific Northwest
Joined: August 22, 2003
 Yes; exactly - sorry, should have mentioned that.

 

4mm here - good for DHTs, posted on June 4, 2015 at 13:10:47
andy evans
Audiophile

Posts: 4378
Joined: October 20, 2000
 I use 4mm aluminium for all builds. I use DHTs like 4P1L which can be a little microphonic, and this keeps the structure solid.

I don't find problems machining it with drills or hole saws.

 

RE: Aluminum plate thickness for amp project, posted on June 4, 2015 at 14:19:27
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Hello,

Thanks for all of the input - very helpful.

Sounds like 1/8 aluminum will be my approach, and there were some good stiffening suggestions if there is a slight issue.

I am hoping to do the machining myself. Something I have to look into. I am trying to maximize my involvement in the project, and feel pretty comfortable tackling most things. I realize the importance of the case, and am fine with spending the time to get it done right (and purdy). I have not worked on anything exactly like this before, so pointers and tool/bit suggestions would be appreciated. I do have a 4" throat drill press that can reach the larger holes for the transformers. Power transformer cutout should be interesting to deal with. Also have to tackle two 2 1/4" diameter holes in the center of the plate to accommodate the 805 tube sockets.

Regards -- Roger

 

RE: Aluminum plate thickness for amp project, posted on June 4, 2015 at 14:56:55
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
 I am with Jeff on this one. I also use a non-magnetic subchassis for technical reasons, flexibility, and cleaner look... But it takes some extra planning.

Regards,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: Aluminum plate thickness for amp project, posted on June 4, 2015 at 18:00:48
kitch29
 Depending where you shop, Lenox, Porter Cable, Milwaukee or Rigid Hole Saws make short work of larger diameters in 1/8" Aluminum. Hammond steel boxes, too. Best are the ones that mount on a separate arbor but the fixed one's are OK, too. Avoid the Skil, Black and Decker, etc.; they might make it through 2 holes.

You MUST use a drill press and clamp the workpiece to keep it from spinning across your Noggin. Cutting oil is essential so don't use the drill press near the new wallpaper in the spare bedroom.

I use step drill bits for everything under 35MM.

Top plates will be supported by a sacrificial piece of plywood on the drill press table but Hammond-type boxes obviously won't. The pressure of the drill press will indent the box. I build a jig out of scraps that supports the box from underneath.





 

RE: Aluminum plate thickness for amp project, posted on June 4, 2015 at 18:04:39
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004



Have no fear. You can do the machining yourself if you have just a few basic tools and some patience. It would be nice to have a drill press with a larger throat, but that's not necessary--you can use a hand drill if you're careful.

IME, the most useful drill bits you'll need are the ones in the attached photo. The one on the left is a stepped bit (aka uni-bit). Very useful for making clean holes up to the maximum size step (in the case of the bit pictured, that's 7/8 inch). The bit on the right is used for starting holes in metal without the bit wandering. Very handy if precision is important to you. (Regular drill bits like to 'wander' when first encountering metal, and your hole may not end up where you'd like it to be. More on that below.) Either of these bits can be used in a press or hand drill.

Other tools that are very useful are hole punches (Greenlee is one brand, there may be others). These make very clean holes (perfect for tube sockets) in metal. Punches aren't cheap, though. If you end up doing a lot of your own metal work, they're worth it. Maybe not so much if this is the only amp you're likely to build.

For the larger, irregularly shaped holes, a jigsaw with a metal cutting blade will get you close (leave your line!). Finish them with an appropriately sized metal file (stop when you get to your line! Aluminum files fairly easily). Your large round holes can be done the same way, BTW. You'd be surprised how close you can come to a perfect circle using this method and some care. Draw large circles with a compass. Compound shapes with straight edge and square, an inverted teacup, or whatever works.

You can cover the entire surface with adhesive backed paper, measure and mark all your holes, then machine. Best practice is to use a pointed punch to make a 'home' for your drill bit. I've used a drywall screw for this in a pinch. Just put it over the hole center mark, and tap it a couple times with a hammer. Aluminum is soft. Then be sure the tip of your drill bit 'finds' the mark you made before drilling. This will minimize the drill bit's tendency to wander.

Of course, as Jeff mentioned, you can have the metal or machine shop do all of this for you, but it sounds like you wanted to have a go at it yourself.

 

RE: Aluminum plate thickness for amp project, posted on June 4, 2015 at 18:06:06
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004
 tip: coconut oil works great as machining oil. Steal it from the kitchen or find it in the Thai section of your grocery store.

 

RE: I come from a long line of Mill Hunkies, posted on June 4, 2015 at 19:28:02
kitch29
 The old machinists all used bacon grease.

Coconut oil? You're people from the Islands Mon?

 

RE: Aluminum plate thickness for amp project, posted on June 4, 2015 at 21:08:06
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 Something that is often looked over is the quality of the cutting tools you use. Get good carbide drill bits from McMaster Carr. You'll be surprised how long they last and how cleanly they can cut!

 

Circle Cutter, posted on June 5, 2015 at 07:50:34
caffeinator
Audiophile

Posts: 1729
Location: Pacific Northwest
Joined: August 22, 2003
 For some of the larger cutouts, I'd also suggest a circle cutter (I linked one just for the picture - no experience with the brand or seller). I've had good luck with step drills, but my experience with hole saws has been somewhat mixed. The circle cutter has been great for the holes beyond the step drill's range, and produces smooth-edged holes that require very little filing.

 

RE: Circle Cutter, posted on June 5, 2015 at 08:37:28
Skip Pack
Audiophile

Posts: 144
Location: Hollister, CA
Joined: November 20, 2005
 + much on this suggestion!

I've used exactly this tool (AKA a flycutter) for 35 years on wood, aluminum, and steel. Pretty much requires a drill press for safety's sake and precision. Make sure the piece you are cutting is well secured, take your time, wear protective gear, spin it slowly and don't force. It works very well.

Skip

 

RE: Circle Cutter, posted on June 5, 2015 at 09:02:45
bouncy ball
Audiophile

Posts: 1221
Location: British Columbia
Joined: July 26, 2003



I have been using this type of hole saw for awhile, they are a bit more expensive but you may find it on ebay from time to time. It makes super nice clean cut.

 

Heavy Transformers, posted on June 5, 2015 at 10:16:21
gusser
Audiophile

Posts: 3649
Location: So. California
Joined: September 6, 2006
 One trick for heavy transformers is to run 1/8 x 3/4in aluminum angle under chassis end to end attached to the transformer bolts. Just like a truss or floor joist.

Ancient civil engineering trick - distribute the weight and get away with thinner "floor material".

I have done this a couple of times on some amp builds.

 

RE: Heavy Transformers, posted on June 5, 2015 at 10:36:40
caffeinator
Audiophile

Posts: 1729
Location: Pacific Northwest
Joined: August 22, 2003
 Heck, you could maybe run it from end to end and use it as a ground buss?

 

RE: Circle Cutter, posted on June 5, 2015 at 10:42:07
caffeinator
Audiophile

Posts: 1729
Location: Pacific Northwest
Joined: August 22, 2003
 Very nice...I've not had the pleasure of using that style of hole saw. Definitely looks like it would do a great job.

One plus on the Circle Cutter is that it's adjustable, so, for occasional use, it's pretty cost effective.

 

RE: Heavy Transformers, posted on June 5, 2015 at 11:08:57
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Hi,

Thanks for the suggestion. I was thinking of running it from front to back, since all of the transformers are along the back of the plate. I figured the tendency would be to sag towards the middle of the plate, so front to back would provide support in the area that would be inclined to sag (as well as effectively divide the panel into 2 10" sections. I have not gone into this too much yet, but would not using this as a neutral bus have the effect of tying together the neutral and ground (my plan was to ground ONLY the aluminum plate and 2 shields for the rca twisted pair cables going to the input tube).

Regards -- Roger

 

Aluminum Panels, posted on June 5, 2015 at 12:35:55
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 For transformers that heavy, I use 6061 plate at least 0.188" thick (I prefer 0.250"). Working a plate that thick requires special tools, but I have a small CNC mill for this. If you're short on tools, I would strongly recommend going to a company like Front Panel Express. I think their products are more limited in terms of thickness, but really, 3mm - 4mm will get the job done. For mounting items like tube sockets from underneath, you can have FPE mill a recess in the underside. The recess can be round, say 2.00" - 2.25", and if you leave a thickness of .040" or .050" in that area, overall panel strength will still be very good.

 

RE: Circle Cutter, posted on June 5, 2015 at 14:44:43
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Wow, those are impressive!! Did not see any on those on eBay....

 

RE: Circle Cutter, posted on June 5, 2015 at 16:03:56
bouncy ball
Audiophile

Posts: 1221
Location: British Columbia
Joined: July 26, 2003
 they are mostly come from sellers from NW area, someone told me they were Boeing's surplus. With a bit of cutting oil, they cut aluminum plate like butter, I use a floor stand drill press.

you may find it in business/industrial section, used. New one is very expensive.

 

Standard Hole Saws:, posted on June 5, 2015 at 16:30:57
gusser
Audiophile

Posts: 3649
Location: So. California
Joined: September 6, 2006
 One trick I have used with standard white hole saws is to clamp two pieces of 3/4in of plywood with the metal chassis between them. This will stop the blade "hunting" when it hits the metal since the top 3/4 piece will stabilize it. And the bottom piece helps control tear out.

I have cut nice clean holes for 3 and 4 inch fans using this technique although some minor edge filing is still required.

 

Standard shipyard practice, posted on June 5, 2015 at 17:51:12
unclestu
Dealer

Posts: 5851
Joined: April 13, 2010
 is to drill a series of smaller holes just within the perimeter of the desired hole. This enables the swarf to have somewhere to go, dropping into the predrilled holes, Slow speed, lots of cutting fluid and you can make a neat cut. Drill press recommended.

Use this technique for wood or metal

 

RE: Aluminum plate thickness for amp project, posted on June 5, 2015 at 18:42:19
glenz10183@aol.com
Distributor or Rep

Posts: 84
Location: New York
Joined: September 27, 2003








I typically use an 1/8 or 3/16" on my chassis'. I have access to my friends fabrication shop, so I go there to do my fabricating. I use a plasma cutter for cutting the square for my power transformer. Otherwise it's the drill press that gets most of my attention. I fold my corners and then weld them. I sand down the welds for smoothness. I recess my bottom plate and then add countersunk screws. I also use a dye for punching holes in the bottom plate for ventilation. Above is a finished project that sports a powdercoat finish.

-George

 

RE: Aluminum plate thickness for amp project, posted on June 6, 2015 at 08:46:44
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Thanks very much for all of your tips and suggestions!!

I have rechecked my layout with the components in place, and will go ahead and order the plate. With all of the help I feel confident that I can fabricate a good looking plate that will serve as a solid foundation for my amp project.

Regards -- Roger

 

RE: Aluminum plate thickness for amp project, posted on June 6, 2015 at 08:53:10
bouncy ball
Audiophile

Posts: 1221
Location: British Columbia
Joined: July 26, 2003
 Talk to the metal shop, check if they have those aluminum with vinyl protection cover on one side, order those type. The shop that I get my aluminum, they even have anodized .125 aluminum, they call natural color, so again it may save you time if you can get those, no worry about oxidation.

remember to cover the aluminum with 3M masking tape while you are working on the layout and drill.

good luck and have fun building.

 

RE: Aluminum plate thickness for amp project, posted on June 6, 2015 at 10:13:13
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 Just so this doesn't fall through the cracks, the issue of mounting small/medium tube sockets is not a minor point. They won't look professional mounted above the chassis, but most are also not designed to mount under 1/8" thick material. If they're mounted that way, the tubes will rest on the chassis, not the top surface of the socket, and they won't seat all the way. This is the (only) advantage to using punched steel. It's stronger than aluminum, so a thinner gauge can be used. Anyway, if you're buying the plate precut in 1/8" or thicker aluminum, it should include a recess in the bottom of the plate around each socket hole. I don't think there's any way to do that later with hand tools.

 

RE: Aluminum plate thickness for amp project, posted on June 6, 2015 at 12:45:38
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Thanks very much for bringing this up - it had not occurred to me. The smallest of the tube sockets is affected as you mentioned, and I certainly will not be mounting it on top of the plate.... It is for a 12au7 tube, and the tube is slightly smaller than the upper lip of the ceramic tube socket (for which the hole will be cut). Careful insertion would probably avoid a problem. My first inclination is to carefully bevel the 1/16th off the top of the plate around the 2 tube holes. Hopefully that will look reasonable if done carefully (not much really needs to come off). Probably would not be able to see the entire tube socket from an almost horizontal perspective, but don't think that will bother me much....

Regards -- Roger

 

RE: Yeah but, don't use all the advice ;-}, posted on June 6, 2015 at 16:36:51
kitch29

 

RE: Aluminum plate thickness for amp project, posted on June 7, 2015 at 06:36:54
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Ran into one other plate related question (so far).....

I need to undermount the 805 tube socket, and am down to 2 options. I can cut a section of Al tube (1/2 dia) and use a through bolt. Option 2 is a ceramic standoff which is threaded on both sides. I am tending toward the Al solution, as I figure the through bolt would be stronger. I can use fibre washers between metal as well as ceramic contacts to eliminate any vibration or rattling. Is there some reason ceramic standoffs would be better??

Regards -- Roger

 

RE: Aluminum plate thickness for amp project, posted on June 7, 2015 at 08:57:03
caffeinator
Audiophile

Posts: 1729
Location: Pacific Northwest
Joined: August 22, 2003
 Either one sounds fine. The ceramic standoffs are likely insulated whereas the through-bolts would be conductive; sounds like you've taken that into account.

I'd use the through-bolt approach mainly for aesthetic reasons - you can get a socket-head capscrew, a countersinked fastener or somethings else that looks good to have a clean appearance on top, whereas the standoff would show a nut and exposed threads. Of course, you could use an acorn nut to dress that up, if that's your style.

Why 1/2" tubing? You shouldn't need very big fasteners for the tube sockets. Even #8 would be overkill, #10 way over, and 1/4-20 crazy over. If your local hardware store has a good fastener section (maybe with those vendor-stocked boxes from Dorman or Hillman, etc.), hunt around, they should have bushings or spacers for standard fastener diameters that should do the trick.

If isolation from vibration is a particular concern, you can get isolating standoffs - they have threaded studs on both ends and a rubber body in the middle. Same problem with nuts on the top surface, and not too sure they are actually necessary or beneficial, but would be the gold standard for vibration isolation.

 

RE: Aluminum plate thickness for amp project, posted on June 7, 2015 at 09:39:23
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Hello,

Thanks for the reply. I am thinking 1/2" od tubing mainly because the recess in the ceramic socket for the support is a bit over 1/2", and I figured I would get as large a support footprint as possible to minimize wiggling of the socket. The through screw can be a whole lot smaller than 1/2". I will probably try to keep the screw size as much the same as possible for the entire plate, since it would look the best and even a small diameter screw probably has plenty of strength for the application.

Regards -- Roger

 

Socket Mounting, posted on June 7, 2015 at 10:46:30
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 Which sockets are you using? The large EF Johnson sockets were designed to be mounted on top of a plate. The bottom of the socket is machined and registered for this purpose, but the upper surface is glazed and only roughly dimensioned. When I designed my 211 amps, I decided early on not to use the top surface of the sockets for mounting. I wanted to be sure there was no slop that could cause vibration, or worse, an uneven mounting surface that might cause the ceramic to crack. The only way to accomplish that was to machine a circular sub-plate that the sockets could sit on. I've never seen anyone else do this, including commercial manufacturers, but I think it's the only way to do it right.












 

RE: Socket Mounting, posted on June 7, 2015 at 13:03:00
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014






Hello,

The sockets were acquired by the initiator/prior owner of the project, and I don't have a clue as to the style/maker.... I have however attached a couple of pictures that will hopefully tell all!!

The upper surface, to which the 1/2" tube would butt, is indeed glazed. I put my small straight edge flat across the glazed base mounting hole, and it does look as though is pretty much perpendicular to the brass cylinder (excuse me for not knowing the proper terminology). I was planning on using a fibre washer (or felt) between the tube and the ceramic as well as the tube and bottom of plate (good buffer to prevent vibration and provides a bit of friction to keep the Al tube from rotating).

Regards -- Roger

 

RE: Socket Mounting, posted on June 7, 2015 at 15:16:19
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
 Not custom or as overbuilt as yours may be, but perhaps okay for common sockets?


"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

Why Do Images Disappear on the Asylum Server?, posted on June 7, 2015 at 19:30:20
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 I can no longer see the image in my post above. If I attempt to view it separately, the Asylum server returns a File Not Found error message. This is a frequent occurrence, but only on this site. Anyway, here it is again...

EDIT: Isn't it odd, the minute I posted this, the image in the post above reappeared. The same exact thing happened earlier today, so I had deleted the earlier repost. Very strange...




 

RE: Socket Mounting, posted on June 7, 2015 at 19:33:52
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 I don't use Chinese parts. That aside, the rings you linked don't appear to solve the problem. Unless I missed it, there's nothing to support the sockets from underneath. Again, some people might not consider that important, but it's not how the sockets were designed to be used.


 

RE: Socket Mounting, posted on June 7, 2015 at 19:46:29
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 Those are Chinese sockets, so I really don't know how well they'll work. Personally, I would toss 'em and hunt up some real EFJ made-in-USA sockets for a project like this. They're pretty common on eBay.

The other potential issue mounting this style socket with nothing underneath is the fact there are only two through-holes. That raises the possibility the sockets will rock and loosen over time. A company like Front Panel Express can probably cut round mounting plates to support the sockets from underneath. It would be worth sending them a sketch to find out.

 

RE: Socket Mounting, posted on June 7, 2015 at 20:18:02
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Thanks very much for letting me know about the sockets - not good news, but better than after they were already in. I will indeed try and run down a pair of EF Johnson sockets. Of course, if these are Chinese, then the 6l6gc and 12au7 sockets are probably the same..... Is it fair to say that if there are no brand marks on the sockets they are Chinese?? As you might have already guess, I am anything but an expert on this.... I am looking to use good quality parts (within some reasonable budget) and put together a solid project. Lucky I am not in a rush !!!

Thanks and regards - Roger

 

RE: Socket Mounting, posted on June 7, 2015 at 21:41:13
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 I'm not sure all the US sockets will show a brand name. However, the pin contacts are formed differently than the ones you have, and no American manufacturer ever gold-plated their sockets. I just ran over to eBay, and all the US-made 211/845 sockets look old and tired at the moment. Be patient and you'll get a good pair, even if you have to buy them one at a time. Vintage octal and 9-pin sockets are easier to find, although they frequently sell for more than I think they're worth. Belton sockets have also been recommended by Jim McShane as a good modern replacement for octals and miniatures.

 

RE: Socket Mounting, posted on June 8, 2015 at 06:03:24
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Thanks for your help in this. I am fine with patience - for some reason I have a strong aversion to Chinese products, so any inclusion would be from ignorance rather than intent. There are some nice NOS vintage sockets out there, and the prices are higher but not prohibitive. Any particular brands I should look for or avoid. I think I am going to stick to ceramic.

Thanks -- Roger

 

RE: Socket Mounting, posted on June 8, 2015 at 06:29:16
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 Some users have reported odd noises or susceptibility to vibration associated with ceramic sockets (octals and miniatures). I can't confirm that, but almost all my vintage sockets are bakelite or similar. The only exceptions are ceramic octals that I use for high voltage applications (more than +750V). Good luck with your project!



 

RE: Socket Mounting, posted on June 8, 2015 at 21:25:33
drummerwill
Audiophile

Posts: 965
Location: St Louis Mo.
Joined: January 7, 2003
I did something similar with my 845 sockets. I mounted them to thick pieces of Teflon, and attached that assembly to my chassis underside..

That's gonna be one fine looking 211 amp.

Willie

 

RE: Socket Mounting, posted on June 9, 2015 at 02:04:34
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
 Fair points TK. I think I understand what you are suggesting now.

regards,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

211 Amps, posted on June 9, 2015 at 08:03:18
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 Thanks, that's a really old photo. These were completed, then torn apart again for various changes. Among other things, I'm adding auto bias for the 211s. I have the design worked out, but it was a challenge because they're A2. If all goes well, I'll have everything done by the end of summer.

 

RE: Socket Mounting, posted on June 10, 2015 at 16:13:04
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 Hello,

I saw a National Co. socket that would work probably better than the Johnson, since the National is built to be undermounted. Any feedback on the relative quality of the two? Is the National a solid socket choice?

Regards -- Roger

 

Lug vs solder tab connections on 805 socket, posted on June 10, 2015 at 16:46:43
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014
 The National socket that seems to offer better mounting has only lug connections, while the Johnson has lug and solder connections. Do solder connections offer better performance, or are the two connection methods pretty much a wash?

Thanks -- Roger

 

RE: Lug vs solder tab connections on 805 socket, posted on June 10, 2015 at 17:47:27
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 Can you post a picture? I don't recall ever seeing anything on these sockets except solder lugs. They're held in place with #10 screws through the ceramic base.

 

RE: Lug vs solder tab connections on 805 socket, posted on June 10, 2015 at 18:44:37
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014



Here is a picture. Looks like he only has one, so not really an option.....

 

Socket Pinout, posted on June 11, 2015 at 09:26:23
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 I haven't used that type. I'm sure it's supposed to have solder lugs between the washers, they've just been removed. Incidentally, not all of these are for the same pinout. If you wire them as marked, and it turns out the G and P are swapped, you'll have trouble. Not really a problem as long as you know about it, but I'd prefer to have those markings in the correct locations if possible.


 

Eby gold plated the sockets for Radar use, I have several and posted such last year~nT, posted on June 11, 2015 at 14:02:37
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 ~!
The Mind has No Firewall~ U.S. Army War College.

 

RE: Eby gold plated the sockets for Radar use..., posted on June 12, 2015 at 08:21:02
Triode_Kingdom
Audiophile

Posts: 10044
Location: Central Texas
Joined: September 24, 2006
 Just to confirm, are you sure it wasn't done after the fact by someone else? I'm also curious how tubes this large (i.e. slow) would be used in radar. Do you have any more info on the origin or use of those sockets (I didn't see your previous post)?

 

RE: Eby gold plated the sockets for Radar use..., posted on June 24, 2015 at 11:47:33
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 Here is the link from AA forum... The British invented RADAR and as you know... the lower the frequency the farther the range... a triode would be more than sufficient, the antennae plays just as big a part as it should match the frequency being beamed, moreover the technology progressed to the cavity magnetron, the beginning of fast food via microwave.


As an aside, {as I have learned} a 6SJ7 may be electrically very similar to a 77 or 6C6... the fact remains, aurally the 6C6 will soundly trounce the 6SJ7... pun intended. As usual, more is going on than just reading by the numbers. Size of the plate for older tubes making a difference?

Perhaps.



The Mind has No Firewall~ U.S. Army War College.

 

RE: Aluminum plate thickness for amp project, posted on July 9, 2015 at 09:15:47
rogerh113
Audiophile

Posts: 506
Location: San Francisco South Bay
Joined: October 20, 2014



Hello,

Thanks to all of your suggestions and advice, I was able to 'machine' the top plate. I am pretty happy with the result, especially for a 'garage job'. I still need to drill a few holes around the periphery once the wood base is completed, and probably a few more for internal supports for caps, etc.

Regards -- Roger

 

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