Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: hesamadman on August 15, 2013, 05:41:33 pm
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Here we are. All the stuff came in the mail today. I mounted my tube sockets and did the heater wires. Much cleaner than before. Could still be better but it is getting better.
I have one tube socket that doesnt match. Well i tried twisting pin 1 and pin 8 sideways so I could just stick a wire straight through it (saw tube depot do it on pre amp tubes) well.... the pin broke. I wont be doing that again.
Any thoughts?
(http://i89.photobucket.com/albums/k205/fratbasher/photo13-1.jpg) (http://s89.photobucket.com/user/fratbasher/media/photo13-1.jpg.html)
(http://i89.photobucket.com/albums/k205/fratbasher/photo23-1.jpg) (http://s89.photobucket.com/user/fratbasher/media/photo23-1.jpg.html)
(http://i89.photobucket.com/albums/k205/fratbasher/photo32-1.jpg) (http://s89.photobucket.com/user/fratbasher/media/photo32-1.jpg.html)
(http://i89.photobucket.com/albums/k205/fratbasher/photo42.jpg) (http://s89.photobucket.com/user/fratbasher/media/photo42.jpg.html)
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It would have been more organized if I ran a black AND red from the transformer but I ran 2 blacks. From the first tube I then ran a red and black. I just didnt have any read when I wired the first set of wires.
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I would rewire the heaters if it were me. The way you have yours twisted the two sides of the AC are not really twisted together at the tubes. Lost of slack there. The idea behind twisted your heater wires is to try to minimize AC hum. Your two AC sides aren't really twisted together much near the sockets. The wires from each individual side are twisted but that doesn't help in heater string noise reduction/rejection. Here's a photo of the heaters from my recent 2204 build. See how the two sides of the heater string stay fairly well twisted only separating at the sockets to connect to the pins? That's the general idea you are going for. Those big loops of slack heater wire that you have may act as radiating antennas for AC heater hum.
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You're learning, hopefully (and I know that may sound snotty) that producing neat wiring is not that easy. Well...it is when you've done it ten times. usually not before.
I myself don't think you'll have any technical (eg; hum) issue with the way it is. But I WOULD try to cut 3/4"-1" out of each of the right hand loops.
One problem as I see it is that your "split" point, the point where the twisted pair coming from the left, feeding the tube, and the "output" pair, feeding the downstream tube make their turn is different for each tube. It is not uniform. I believe you could get a better look if you tried to make the split point uniform...and it could be 7 o'clock, 6 o'clock, or 5 o'clock relative to any tube. But: All the same.
And, I would focus less on twisting the input & output wires-to-the-pin together once they make the turn. One of the conundrums is, if you twist several feet of wire in a twist drill to make your complete filament string, then cut that long length up, when you go to unwind the individual wires to make the connections per-tube, the wire is usually coiled up to an extent that you can't really uncoil it well. You can see this on the last tube in your chain. The single wires look "twisty". The individual wires taken out of the twisted pair will still show curviness and it is hard to get out. What's funny, is if you go to Google Images and look up "filament wiring" you'll get about 8 different techniques. Some of this is personal style. I like (without claiming this is any kind of "standard") to have the "Main line" twisted and when the indiv wires make the turn, they are untwisted but very coherent with each other. Like on Sluckey's pix on the orig thread. (Except he did not twist his "main line". But the indiv wires going to the tube....I like to see those so on top of each other with the same curvature, that they look like only one wire. >>IT'S NOT EASY TO DO THIS laid against the chassis! It's MUCH easier to produce a cleaner looking string wiring it "fender-style, "up in the air".<<
Anyway, to get that look, you pretty much have to cut & strip the two individual wires going to each pin at the same time. It helps to handle everything less. Untwist less, bend less.
Keep at it. I absolutely promise you, the first 20 things I built looked sketchy. I applaud your willingness to accept constructive critique.
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You're learning, hopefully (and I know that may sound snotty) that producing neat wiring is not that easy. Well...it is when you've done it ten times. usually not before.
I myself don't think you'll have any technical (eg; hum) issue with the way it is. But I WOULD try to cut 3/4"-1" out of each of the right hand loops.
One problem as I see it is that your "split" point, the point where the twisted pair coming from the left, feeding the tube, and the "output" pair, feeding the downstream tube make their turn is different for each tube. It is not uniform. I believe you could get a better look if you tried to make the split point uniform...and it could be 7 o'clock, 6 o'clock, or 5 o'clock relative to any tube. But: All the same.
And, I would focus less on twisting the input & output wires-to-the-pin together once they make the turn. One of the conundrums is, if you twist several feet of wire in a twist drill to make your complete filament string, then cut that long length up, when you go to unwind the individual wires to make the connections per-tube, the wire is usually coiled up to an extent that you can't really uncoil it well. You can see this on the last tube in your chain. The single wires look "twisty". The individual wires taken out of the twisted pair will still show curviness and it is hard to get out. What's funny, is if you go to Google Images and look up "filament wiring" you'll get about 8 different techniques. Some of this is personal style. I like (without claiming this is any kind of "standard") to have the "Main line" twisted and when the indiv wires make the turn, they are untwisted but very coherent with each other. Like on Sluckey's pix on the orig thread. (Except he did not twist his "main line". But the indiv wires going to the tube....I like to see those so on top of each other with the same curvature, that they look like only one wire. >>IT'S NOT EASY TO DO THIS laid against the chassis! It's MUCH easier to produce a cleaner looking string wiring it "fender-style, "up in the air".<<
Anyway, to get that look, you pretty much have to cut & strip the two individual wires going to each pin at the same time. It helps to handle everything less. Untwist less, bend less.
Keep at it. I absolutely promise you, the first 20 things I built looked sketchy. I applaud your willingness to accept constructive critique.
I noticed that my first tube pin 2 heater wires were not twisted also. After I had wired it, but I checked out a lot of other builds and assumed I may be Ok. All of the things you mentioned, I will take into consideration on future builds. As far as changes on this one, the only thing you suggest I do is cut back some of the excess on my first preamp tube?
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Two wires twisted together that go to the same pin doesn't constitute a "pair" in a "twisted pair" hum reducing wiring scheme. those big loops you have that go to the same pin are more less a single wire that happens to be twisted together. The 'pair' runs 2" apart for 2-3" untwisted...
Here's what I'd do: Run the pair from the PT in the corner of the chassis, like you have it, to pin-2, connect one lead to pin-2, and the other run over the top, across the tube socket, to pin-7. For the next tube, pin-7's wire comes back over the tube socket to meet up with it's "pair" on the chassis side of pin-2. And then twists it's way down to the next power tube. No big loop around the base of the tube socket, the PAIR goes 'unpaired' for 1" or so, instead of 3+"
Also, most preamp tubes (12ax7) have lower amperage requirements than power tubes, so you can use 20 (or even 22??) gauge wire as you move down the chain after the power tubes.
(If that makes twisting easier).
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I would just make the four changes I've indicated and leave it at that. You probably want to eliminate the "foldback-and-tape" or "foldback & tie-wrap" thing you did. As you can see, you've created those foldback points far enough away from the socket so that you are forced to make those big wide arcs with the black-black @ 1 & 2. But/And...if you do that NOW you are going to be left with narly bends in the black which, judging by the first preamp tube, you won't be able to smooth out of the wire that well.
These techniques originated over the old-timey desire to create so-called "service loops" in wiring, where the ideal was to be able to cut the wire TWICE and resolder it to the terminal with excess wire that was there from original construction. Let us update our view so that if properly done, filament wiring, in particular, might be passed on to our grandchildren without having to resolder wires. Thus we don't need the excess, we don't have to do that foldback thing.
Not all wire is created equal in terms of how it behaves when twisted.
When it is all said and done, IMO the better look results NOT from twisting 3 feet of wire in your drill and then cutting it into 3" lengths and then unwinding to reach the indiv sockets. It comes from using nice, relaxed wire and hand-twisting in between sockets. Other will disagree with this. When you twist in the drill, it is VERY easy to overtwist and then you get that curly look when you unwind it. And it (that curliness) is hard to get out and it's hard to make the two wires going to one terminal nice and coherent with each other....which to my eye, makes a better look. Understand, I am just sharing my experience and not trying to tell you how to meet NASA specs. Understand also that we are strictly talking "look"...in the end, none of this matters in any measurable nor visible way once the amp is buttoned up.
(http://i172.photobucket.com/albums/w32/ttm4/wiring_1_zps421dde48.gif)
Just shorten the wide arcs (1 & 2) in the black-black and get the "split" or "breakout" point on the first preamp tube more like at 6 o'clock to that socket.
There is such a thing as overobsessing over this. The good look comes from evenness and repetition of the size and shape of the arcs. I am not going to tell you this comes easy. When you are starting, it seems like a lot of tedious work, but hopefully this is a learning experience for you and you seem to know that learning is often irritating.