Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: p2pAmps on April 22, 2016, 04:59:03 pm
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Cheers from Nashville...
I am making a very poor quality video showing how I build a Hoffman PR amp. I will keep adding more as I go along but my hopes are I will help those of you who are just getting started. The techniques I use work for me but are by no means hard and fast rules as there are always many right ways. If you can pickup on anything I am doing that helps you that would be great.
Disclosure. I suck at making videos and trying to hold my iPhone with one hand while doing a task will be painfully obvious ...
Mike
! No longer available (http://www.youtube.com/watch?v=qPTSCCxncfs#)
and part 2
! No longer available (http://www.youtube.com/watch?v=QFg8wqKaNcg#)
Part 3
https://www.youtube.com/watch?v=vb9rm_yAhSI&feature=youtu.be (https://www.youtube.com/watch?v=vb9rm_yAhSI&feature=youtu.be)
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Great Video thank you for sharing
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People type "lol" but I actually did laugh out loud uncontrollably when a saw "Tremendous Reverb Amp"!!
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People type "lol" but I actually did laugh out loud uncontrollably when a saw "Tremendous Reverb Amp"!!
LMAO... I'm a smart ass what can I say !
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No, I think it's accurate for your Fender-style amps!
And great work on the video! I watched it and know there will be a lot of new builders who will certainly appreciate you pointing out all the fine points of what seem like "obvious tasks" (but really aren't until you've boogered a few of your own builds).
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Nice, Mike!
Here's a little thing I do on the drill press when I need to cut out a straight line in metal. You may find this useful for drilling out your wire feed-thru holes in the parts board, to get those holes uniformly spaced away from the turrets. Since you're the neat freak!
Using 2 "C" clamps, clamp a piece of wood to the drill press table as a fence. Shown here on my 1938 Cincinnati. The fence does not need to be straight relative to the table. Be sure the bit does not hit the table when it drills thru your work. Now you can drill any number of holes all equidistant from the fence.
1: On metal, soon you will produce enough burrs on the underside so that the work will not sit flat on the table. File or grind them off periodically as needed.
2: Use a VERY short bit, or have it sucked up into the chuck so that very little is exposed. The less drill exposed, the closer together you can make the holes. Eventually you will break off a bit when it wanders. No getting around it. Go buy somebody's envelope of drill bits at a flea market so you have a dozen you can bust now and again. Best is to have only say 3/4 of an inch sticking out of the chuck. It takes a little practice to determine how closely you can drill the holes, and it's different in steel vs alum.
(http://i172.photobucket.com/albums/w32/ttm4/2004-12-31%2023.00.00-12_zpsf2wfaaq7.jpg) (http://s172.photobucket.com/user/ttm4/media/2004-12-31%2023.00.00-12_zpsf2wfaaq7.jpg.html)
Of course you could use a hacksaw to cut the metal without the drilling, but if the holes are there you can cut a large piece of metal super fast by joining the holes, cutting along the line of holes. It's definitely more useful when cutting out a square opening for a transformer. Use a cruddy old pair of dykes to cut out the undrilled area between holes, remove the cutout piece, then file away. Makes nice straight lines if you're careful. Yeah, the leftover piece of metal has a phenomenally sharp and raspy edge on it before you file or grind it off. Wear gloves.
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Key Point for you new solder-slingers:
At about 7:25 of Part 2, a wire is being soldered to a turret. Look very close and you'll see the iron is contacting both the turret and a portion of the wire on the right side of the turret. The solder is being added from the left side of the turret.
To get a good solder joint, both the turret and wire need to be hot enough to melt solder. It is not enough to use the iron to place molten solder on the joint, even though it might seem to hold (but really won't if you apply force to the joint). So you heat the work and apply the solder to the work a bit away from the iron itself. When the work is hot enough to make a good joint, the solder will melt.
Also notice the moment there's enough solder on the joint, you get the iron off of it. That happens about 7:29 in the video. Turrets and teflon wire don't mind heat, but some components can't handle prolonged heat, and PVC-insulated wire will have its insulation melt back away from the heat. While bigger parts will take longer, you'll see it's all of 4 seconds to apply heat, solder and get off the work. (The total time will really depend on you having an iron sized appropriately for the mass of the item you're trying to solder)
High-five for good soldering technique!!
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This is awesome....boy wish I watched it before I struggled through mine , but all good :P
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I'm still watching them, but they're outstanding, thanks! Subscribed :) (on both my personal and my film one where I do my builds)
~Phil
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Nice, Mike!
Here's a little thing I do on the drill press when I need to cut out a straight line in metal. You may find this useful for drilling out your wire feed-thru holes in the parts board, to get those holes uniformly spaced away from the turrets. Since you're the neat freak!
Using 2 "C" clamps, clamp a piece of wood to the drill press table as a fence. Shown here on my 1938 Cincinnati. The fence does not need to be straight relative to the table. Be sure the bit does not hit the table when it drills thru your work. Now you can drill any number of holes all equidistant from the fence.
1: On metal, soon you will produce enough burrs on the underside so that the work will not sit flat on the table. File or grind them off periodically as needed.
2: Use a VERY short bit, or have it sucked up into the chuck so that very little is exposed. The less drill exposed, the closer together you can make the holes. Eventually you will break off a bit when it wanders. No getting around it. Go buy somebody's envelope of drill bits at a flea market so you have a dozen you can bust now and again. Best is to have only say 3/4 of an inch sticking out of the chuck. It takes a little practice to determine how closely you can drill the holes, and it's different in steel vs alum.
(http://i172.photobucket.com/albums/w32/ttm4/2004-12-31%2023.00.00-12_zpsf2wfaaq7.jpg) (http://s172.photobucket.com/user/ttm4/media/2004-12-31%2023.00.00-12_zpsf2wfaaq7.jpg.html)
Of course you could use a hacksaw to cut the metal without the drilling, but if the holes are there you can cut a large piece of metal super fast by joining the holes, cutting along the line of holes. It's definitely more useful when cutting out a square opening for a transformer. Use a cruddy old pair of dykes to cut out the undrilled area between holes, remove the cutout piece, then file away. Makes nice straight lines if you're careful. Yeah, the leftover piece of metal has a phenomenally sharp and raspy edge on it before you file or grind it off. Wear gloves.
Hey there,
So yeah I like the idea of using a fence on the drill press. I actually have one I made for mine with a stop. In the case of the turret board I can eye ball it in and it is super close so I just do it that way. Your way would certainly be precise however. When I have done G10 eyelet boards for twins and Bassmans I do use my fence as there is a long row of holes to drill.
I really appreciate any comments as I am always looking for more ways to perfect what I do.
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:nice1:
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Great thread.....some of us schematic readers who think we can build need to see this stuff.....because the schematic and layout drawing seems tougher once you start to actually try to put it together, there is more involved and I for one love to see how you all do it :)