Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tbone55 on October 09, 2021, 05:05:07 pm
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Hi To Everyone Here,
I performed the Blues Jr Mod just before Covid started and the amp seemed to be working perfectly. A little bit of noise but not anything abnormal. Since then I haven't played it and the other day decided to to give it a workout. It seemed to be a lot more noisy than I remember. If you turn either the volume or master volume up the noise gets louder. I honestly don't remember the amp being this way.
Would appreciate suggestions on starting to trouble shoot this problem.
Thanks.
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> a lot more noisy
"Noise": Hiss? Hum? Buzz? Whine? Bleeps? Rattle? Crackle? Gurgle? Martian radio?
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I performed the Blues Jr Mod
Which Mod? The Hoffman Blues Jr. Conversion? or the repair of the tube mounting board? Or, one of the many BillM mods?
It's hard to offer advice without knowledge of the "mod" in question.
The Hoffman BJ Conversion should be very quiet.
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My apologies, should have been a bit more specific with respect to what noise and which mod I did.
I did the Hoffman Blues Jr Conversion to a turret board and tube sockets.
I would probably define the noise as hum and a bit of hiss. I should add that I didn't use the stock Blues Jr power transformer but opted for one a bit more powerful that came standard in another Fender model. I can't recall the model number but it's a Hammond transformer that's readily available. Bill recommended it to me.
Thanks.
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Bill Machrone? The father of BJ mods? (and my favorite journalist of all time).
IMO, these amps do hiss a bit. Should not be bad. They generally don't hum, at least in my experience, and I have owned three of them.
Do you think this is a 60 cycle of 120 cycle hum? Does it hum when the instrument is not plugged in? Does the environment have an effect (eg, one location vs another)? Do you have a lot of Led bulbs in the area (I have one spot in my house with LED strip lighting that is very noisy and is to be avoided). Does it change when volume is turned up or down? Does it change when V1 is pulled?
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Picture of the wiring may be usefull
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Latole is correct.
This is a PCB amp, modded with a power transformer and Hoffman tube socket board.
So it is possible that his AC wiring has strayed close his signal path, or the socket board has been miswired.
Edit: My bad, I missed the turret board part of his reply.
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It's modded with a turret board and a tube socket board, AFAIK because that's what he said. That would make it no longer a PCB amp.
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TBone is this what you have https://el34world.com/Hoffman/images/Img_8758_small1.jpg
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TBone is this what you have https://el34world.com/Hoffman/images/Img_8758_small1.jpg
Yes, that's it.
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Bill Machrone? The father of BJ mods? (and my favorite journalist of all time).
IMO, these amps do hiss a bit. Should not be bad. They generally don't hum, at least in my experience, and I have owned three of them.
Do you think this is a 60 cycle of 120 cycle hum? Does it hum when the instrument is not plugged in? Does the environment have an effect (eg, one location vs another)? Do you have a lot of Led bulbs in the area (I have one spot in my house with LED strip lighting that is very noisy and is to be avoided). Does it change when volume is turned up or down? Does it change when V1 is pulled?
I think it's 60 cycle hum. Without the guitar plugged in (Stratocaster) I get very little hum when I turn up the master volume and a bit of hiss when I turn up the volume but amp I'd say is quite quiet. Sounds like the single coils are picking up the hum. I do have Led recessed lighting throughout my basement. Plugged in my humbucker guitar and the amp was almost as quiet as without having a guitar plugged in. With coil split option activated on this guitar the amp still remained relatively quiet. Its looking like the single coils of my strat are the problem. I've got the cavity shielded and a shield underneath the pick up cover as well. This amp is a monster. Turning the master volume just past 2 is loud. You have to turn the input volume all the way up just to get some breakup. Tons of headroom in this amp.
Thanks for the help. If you have any other suggestions please let me know.
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I had to laugh because I just built an offset g-tar with Jazzmaster pickups and went through the same thing with one of my Fender BJs in the workshop. The guitar was about 90% done, and the time had come to check the wiring of the guitar, so I plugged it in and I got a buzzing sound like a bee in your hat. All of my other guitar builds have been with humbuckers, or with active single coils. That is, very quiet.
The Jazzmaster pickups are noticeably noisier. This is a known thing, of course, but I wasn't ready for it and thought: "What the hell is my amp doing now?" Well, of course, all was ok when I shielded all the guitar wiring and cavities -- in other words, finished the project. And my amp is back to normal! Except when it is directly beneath this one LED strip in the ceiling . . .
Anyway, best of luck with your amp. I built a Hoffman BJ about 5 years ago, and it is solid as a rock, very quiet, sounds good, takes pedals well -- and it's not my shop amp that buzzes with the LEDs.
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Acheld,
I have a Jazzmaster at home. A real '60, she's very quiet.
Someting wrong with yours
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Well, of course, all was ok when I shielded all the guitar wiring and cavities -- in other words, finished the project.
sounds like there is no problem to me
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I had to laugh because I just built an offset g-tar with Jazzmaster pickups and went through the same thing with one of my Fender BJs in the workshop. The guitar was about 90% done, and the time had come to check the wiring of the guitar, so I plugged it in and I got a buzzing sound like a bee in your hat. All of my other guitar builds have been with humbuckers, or with active single coils. That is, very quiet.
The Jazzmaster pickups are noticeably noisier. This is a known thing, of course, but I wasn't ready for it and thought: "What the hell is my amp doing now?" Well, of course, all was ok when I shielded all the guitar wiring and cavities -- in other words, finished the project. And my amp is back to normal! Except when it is directly beneath this one LED strip in the ceiling . . .
Anyway, best of luck with your amp. I built a Hoffman BJ about 5 years ago, and it is solid as a rock, very quiet, sounds good, takes pedals well -- and it's not my shop amp that buzzes with the LEDs.
Well, guess I'm not alone after all. We all seem to get ahead of ourselves and then fall behind creating problems of our own doing. :laugh: I have to agree, this amp is rock solid and really takes pedals well. It has so much headroom. I do have my strat shielded with copper foil and also have a shielding plate under the pickguard. The shielding and the pickguard plate are connected as they're supposed to be. My last option is to shield the pickups themselves with shielding tape and copper tape and ground it to the negative side of the coil. I remember an article in Premier Guitar about doing this. Will have to check it out. One other thing, my POD HD500X seems to introduce noise itself even though I have a noise gate in the patch. I don't hear any noise with headphones connected to it. Electrical stuff, go figure.