Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ratgon on February 11, 2016, 06:15:30 pm
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Sorry to bring this up again and so many people have reached out to help but I'll be damned if II can figure out how to get this thing running. At first it was silent and some very nice help addressed that so now the amp is clearly on, humming and such but I cannot figure out what to do with the inputs. There seem to be so many different approaches to it. Hoffman's layout only addresses 2 of the four inputs. Other sites have approaching the majority of input resistances on board. etc. I KNOW i'm just completely freezing up over this thing but I'd give anything for a straight illustration or pic of someone's Hoffman 5E3.
Thank you!
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Try hooking up just one. Get the amp working with that one, then worry about the other 3. At least, that's what I'd do.
In fact, I've never hooked up 2 inputs. It's too complicated for me. :laugh:
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I'm almost ashamed to tell you I have tried that. With switch craft and the Marshall type. But let me ask you this. If I just hook up one simple one do I bridge the two grids together since now pin 7 has no input going to it?
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No.
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So just leave 7 open then? Thanks
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Temporally ground it to kill any noise. :icon_biggrin:
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I gave you a link to a very clear explanation of how to wire those jacks. An actual picture that is annotated, even showing where to make a solder connection. What don't you understand about that?
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Here is a snip-it from the 5E3 schematic.
Uncle Doug on Youtube has a video where he explains in detail the classic Fender input circuit.
There are some changes necessary when you go to a single input configuration.
But those changes just make the circuit perform the same as when you use just the Hi input jack on the Fender circuit.
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Sluckey....you absolutely did and if I didn't thank you then then I am now. Truly. In fact that configuration is where it stands now. Exactly as it appears in the picture. The only thing I've done differently is to add the shielded cable from the junction of the two 68k resistors to V1.
Clearly the issue lies with me. Maybe the issue lies elsewhere. God knows the isn't a lack of help from you all. The whole lot of you have been super patient trying to help me with this.
The irony is that I got my EE degree but instead of ever using it I moved to LA to become a rockstar. So you can imagine that I feel even a bit more like an idiot now.
But Rudy, thanks for your help. All of you. I really dig this forum and this whole new obsession with trying to learn all this stuff. And I can honestly say I've tried every bit of advice given. So obviously somethings wonky on my end.
But I'm gonna keep trying.
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And thank you Paul as well. You've been a big help as well.
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Exactly as it appears in the picture.
Then the problem lies somewhere else.
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Exactly as it appears in the picture.
Then the problem lies somewhere else.
I can't remember if Sluckey or I posted this link yet, BUT this is what you need to do. It's a great way to double check your wiring. :icon_biggrin:
http://el34world.com/Forum/index.php?topic=17701.0 (http://el34world.com/Forum/index.php?topic=17701.0)
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So I'm not even clear on what your symptom is now. :w2:
Apparently you made a change to the output that has the amp making some sound now.
No more Silent amp. :icon_biggrin:
But then you went to the input and confused me. :dontknow:
The Hoffman 5E3 shows 2 single input jacks each feeding through 1/2 of a 12AY7.
Is this how you built it?
Or do you have 4 input jacks?
Which is basically just putting a Hi & Lo on each of the original inputs. :dontknow:
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Ratgon, my impression, for what it's worth, is that you have too many projects and too many threads and just generally too much going on at once. This is not a good state of mind to be in when you're working with electricity. My recommendation is to put everything on the shelf and walk away from it for a few days or a week. When your mind is clear and you're ready to resume, pick one (1) of the non-working amps, and start over again with the step by step diagnostic process that I believe several of the members have referred you to. Do not look at or even think about the other ones, or be scanning Craigslist for yet more projects, until you get this one figured out and working properly.
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And I'm still betting that when you figure out what is wrong with one of those amps, you'll discover that it's a simple mistake that you made on all three amps. I would tackle the 5F1 first since it's the bone dry simplest of the three.
Post some more big pics of the 5F1 that show the entire amp.
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Ratgon, my impression, for what it's worth, is that you have too many projects and too many threads and just generally too much going on at once. This is not a good state of mind to be in when you're working with electricity. My recommendation is to put everything on the shelf and walk away from it for a few days or a week. When your mind is clear and you're ready to resume, pick one (1) of the non-working amps, and start over again with the step by step diagnostic process that I believe several of the members have referred you to. Do not look at or even think about the other ones, or be scanning Craigslist for yet more projects, until you get this one figured out and working properly.
YES, YES, YES!
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And I'm still betting that when you figure out what is wrong with one of those amps, you'll discover that it's a simple mistake that you made on all three amps. I would tackle the 5F1 first since it's the bone dry simplest of the three.
YES, agree!
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Exactly as it appears in the picture.
Then the problem lies somewhere else.
I can't remember if Sluckey or I posted this link yet, BUT this is what you need to do. It's a great way to double check your wiring. :icon_biggrin:
http://el34world.com/Forum/index.php?topic=17701.0 (http://el34world.com/Forum/index.php?topic=17701.0)
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Okay, here's the deal in a nutshell. A big nutshell but still a nutshell. First things first I just want to thank you all for your help and patience the last week or so since I found this forum and started barraging you all with all my unfocused questions and issues.
About five months ago, out of nowhere, literally out of just nowhere I got the idea to want to learn how to make tube guitar amps. About a year ago I finally finished and released a record I'd been wanting to make for years and years and finally spent about a year making this full double record. So anyway it was done and I just wanted to make something. I play guitar but I've never been a gear guy so having this desire to want to learn all about tube amps was kinda outta left field. So I start looking for a kit to build. I found one and built it. Then another. And then another. This whole time I'm reading alI can about this whole little world of tube amps. Usually my creative obsessions last about 2-3 days. Like clockwork. So at about three months of obsessively building three kits and trying to mod them I figured I'd start trying to build from schematics, parts lists and layouts. That led me here and also to all the amazing Uncle Doug videos and trying to build one of his projects.
Cut to a week or so ago when I started reading the forums here and realized there was this whole group of people into this whole deal for the same reason as me. Just the love of building something.
So basically you all encountered me at a particularly obsessive, excited and completely unfocused period. Mind you, five months ago the idea of how a tube amp might work had really never crossed my mind beyond whether or not my amp might need new tubes or not and who should I call to sort that out for me.
But a bunch of you said and echoed the same basic thing. Basically settle my ass down and focus. Great advice.
The bottom line is that I just fucking love all this stuff and I'm really stoked to have found a whole crew of people into this stuff who know so, so much more than me.
So thanks again for all your help and your patience. I'll reel it in a bit. It's getting kinda crazy with half a dozen works in progress around here which, of course, just leads me to the next obsession. Woodworking for the cabinets.
Thanks
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By the way, I stayed up all night working on a mod on yet a different amp but I'll save all the questions it raised for later.
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It's all good!
I tend to get scatterbrained myself when excited. :l2:
Excitement can push you to learn and do so much more.
But that excitement can die a rather horrible death without keeping the car on the road and crossing the finish line once in a while. :w2:
That excitement can turn into dread, if every time you get behind the wheel you end up crashing into a tree or just stuck in the ditch. :sad2:
How about we focus on getting you across the finish line with your 5E3? :think1:
Then maybe you can try to make it around the course in a different vehicle. :BangHead:
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Thanks Paul. Good advice. And as for Slucky's posted pics of how to wire the input, I have done it and he's right. Obviously the issue lies somewhere else. So I'll start with going through Hoffman's wiring checklist again. Eventually something will expose itself.
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By the way, I stayed up all night working on a mod on yet a different amp but I'll save all the questions it raised for later.
So you put a turbocharger on a vehicle you couldn't get across the finish line in it's un-souped up state? :dontknow:
Let's get you making multiple laps around the course, before buying nitros kits and installing them on your vehicle. :BangHead:
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And I'm still betting that when you figure out what is wrong with one of those amps, you'll discover that it's a simple mistake that you made on all three amps. I would tackle the 5F1 first since it's the bone dry simplest of the three.
Post some more big pics of the 5F1 that show the entire amp.
I changed my mind!
I'm with sluckey on this one.
Let's get you around the course in the simplest vehicle you got! :icon_biggrin:
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I couldn't resist throwing up a shot of current works in progress and my breadboard system that i made but is currently in a state of metamorphosis as I build little modular breadboard systems for add-on mods. All silent of course.
I'll get some proper Champ shots up shortly. It's in a state of dissaray at the moment as well but I really would love to get that one done first!
Thanks.
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I've got a lot of vehicles in various states of build too.
But I do have 2 working vehicles to drive in this pic, the 2 on the right side of the pic.
They are also a good guide for me to use in building more like them.
As a recording artist, you are like an F1 driver.
You are now attempting to build and design your own race car.
You are experiencing temporary distress about taking your newly built vehicles on the track,
and the wheel falls off, the exhaust is dragging, and the steering is not responding to your input.
Resulting in you being stuck in the ditch.
I know you can drive the hottest vehicles in production, but since you are now building your own vehicle.
You need to start with a very simple design, that after you built it will take you around the track.
Then you can ride it hard and see if there are some things you would like to improve in it's design.
The Champ is a great simple vehicle to start with. Then you could try to change it's motor.
I like a Champ with a 6AQ5 as it's motor, and a 6BQ5/EL84 is also a good motor to test out in the Champ design.
The Army taught me KISS. (Keep It Simple Stupid).
After you've built some Champs, and then swapped their engines, then you can move to a simple PP 2 cylinder design to build.
Your 5E3 comes to mind, as the next hill to climb after getting some Champs past the finish line.
By the way, your breadboard is impressive for a newbie! Better than mine. :laugh:
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Hey Paul, I dig that analogy. It's funny, after I finished my first kit I sat there looking at it for a week. I dreaded turning it on. Clearly it wasn't going to work and I'd never figure out what the hell the problem was. Well, I finally just said screw it and followed the first time power up instructions. Worked and sounded perfectly!
And thanks for the breadboard compliment. The best thing about it is the use of those rows of springs. Just push em forward and stick in the wire.