if you do guitar amp repairs for any time at all, you will likely come across someone like the guy in this Vid:
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His Fender Pro 185 ( 150watt rated with 2 x 12inch speakers ) has a small amount of background hum, plus a slight hum in the reverb. But that is NOT how he sees it.
Repairers can be expected to fix faults that develop, but something that has been that way since manufacture is another story - often being near impossible or uneconomic to fix.
The two repairers mentioned wisely chose not to waste time trying.
amount of background hum, plus a slight hum in the reverb. But that is NOT how he sees it.
has been that way since manufacture is another story - often being near imp ossible or uneconomic to fix.
Many things are uneconomic, and some customers unreasonable. But fixing bac kground hum from new is often an easy job. If the psu is unregulated, addin g lf filtering sometimes sorts it. I used to like CDC filters, capacitor di ode capacitor, the D acts as a low R nonlinear resistor. The upside is volt age drop is limited, and the filtering gets better as output volume drops. Of course hum can also be caused by a host of other things not as simple to fix.
Reminds me of the guitar amp that had had the wrong transformer fitted, giv ing twice the wanted voltage. Distorted & cut out often. A rework of the ps u configuration sorted it. It's a lot easier if the transformer gives half the required voltage!
** As the background hum in the Pro 185 is independent of control settings, I have a hunch that is due to magnetic field from the AC transformer infecting the earth/ground patterns on the PCB near it.
That is industrial equipment, for use on stage. Not for home listening levels. The hum is quite quiet compared to the volume of the unit that it would be well within the original specs.
I have the same problem in my field. Our pinball games use industrial style art, chrome, electronics, etc. They hum, whistle, rattle and make all sorts of mechanical noises that may be a nuisance in the home, but inaudible (relatively speaking) in an arcade - where the equipment was designed to be used defines the minimum acceptable background noise levels.
Once I point that out most people are quite understanding!
Actually, that is the point. If the hum is at the same level no matter how loud it is set, it is simply not suitable for home use or whatever. There i s such a thing as a power soak though that can cut the output itself down w hich would take the hum with it.
At the music store there was a discussion about fan noise, I said something to the effect that when you are on stage they never hear that, but when yo u are at home listening to Mozart or some shit, that is different.
Most people do not use a 150 watt amp to practice in the kitchen. That does n't mean they are not assholes.
w loud it is set, it is simply not suitable for home use or whatever. There is such a thing as a power soak though that can cut the output itself down which would take the hum with it.
ng to the effect that when you are on stage they never hear that, but when you are at home listening to Mozart or some shit, that is different.
esn't mean they are not assholes.
It doesn't make them assholes either. It's the wrong attitude for a custome r facing position.
Well, at least the youtuber didn't trash the two repairers who looked at it.
One should never believe a technician who has been doing repairs for decades, but if it's on the internet, it must be true. Therefore...
The commenters below the video probably convinced him that the noise he's complaining about is part and parcel for that type of amp.
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I think the customer's main beef is the amp is too noisy to record.
Now, it could actually turn out to be this customer does not know how to record a typically noisy combo, and this is all a bit of a red herring.
He might be needlessly compressing the f**k out of it, which raises the noise floor by the amount of compression applied. You are REALLY going to hear that hum now.
Whatever, I think the customer doesn't have much of a clue about what he has, and how best to use it.
When I worked at the music store a couple years ago, they had a digital eff ects box. this is meant to go in the effects loop of an amp or a mixer. the y had it right between the guitar and the amp. HELLO, this thing is designe d to operate on 300 or 400 mV, not TWO that you are giving it !
should be outlawed. A speaker cable is used on the input from the guitar to amp and they wonder why it hums. And then a shielded cable designed for lo w level, they plug a speaker into a 400 watt amp with it and wonder why it goes bad.
There's more, they had a little band, actually not bad, but the guy decided he wanted a speaker switcher on these two amps, one was BTL and the other wasn't. Blew the breaker in the wall. Yeah - "I never connected them togeth er". Well then how come we got blown outputs in both and they blew the main circuit before the internal AC fuses blew ?
One time they could tell I drank the night before, and I mean drank. I wasn 't feeling all that great, not a hangover but kinda close. so I go to say m y goodbyes at the end of the day and the boss says "Get you to a bar immedi ately". Well he had a heart attack and is dead and I am alive, and he was a bout ten years younger than I. So there. Rot. Meantime I will be well prese rved. LOL
Phil likes to f*ck with me but so what ? I know what the f*ck I am doing an d nobody can take that away. They are fixing my eyes this year and I am get ting my resume' or CV whatever ready. If nobody bites I will start my own e nterprise, and then pay zero taxes. HAHA.
I was in very bad physical shape but that is changing. They told me I almos t died after the injury, but I didn't. Almost died is my middle name and I will be baack.
At any rate, people are so clueless, they'll plug a magnetic cartridge into a tape loop and wonder why it is not loud enough, and a tuner into the pho no and wonder why it is so muffled and distorted.
Seems to me if you had a way to dispose of the bodies...
** He kinda did really - suggesting they must be deaf not to hear the obvious ( to him) humming.
FYI: The Fender Pro 185 has a FET muting circuit which opens when a jack is plugged into the input - that is why he plugged in a lead, fingering the tip to get some hum.
I also wondered for a minute if the power is that room might be missing its earth link.
Anyhow, I posted the vid so folk could observe the typical whiny attitude of these "never happy" kind of guys.
mall amount of background hum, plus a slight hum in the reverb. But that is NOT how he sees it.
hat has been that way since manufacture is another story - often being near impossible or uneconomic to fix.
t it.
vious ( to him) humming.
k is plugged into the input - that is why he plugged in a lead, fingering t he tip to get some hum.
ts earth link.
of these "never happy" kind of guys.
These are the types of guys that would comment on the sound of their band t o me at the board. I would usually direct them to an unused channel to adj ust. Each time the "adjustment" would make a difference to the sound of th e band. pretty amazing for an unconnected channel...
** I used to get that BS a lot once from incompetent studio "engineers".
Dynamic mics were often pushed up against the grille cloth of a cab ( live sound reinforcement style ) and significant hum then heard in the control room monitoring.
Fact often was the amp did not audibly hum at all - the mic ( usually a Shure 57 or 58) was picking up supply frequency mag field from the amp's power transformer.
Any dynamic mic's voice coil alone can do this plus 57s & 58s have *unshielded* matching transformers in the handle that do an even better job.
** I used to get that BS a lot once from incompetent studio "engineers".
Dynamic mics were often pushed up against the grille cloth of a cab ( live sound reinforcement style ) and significant hum then heard in the control room monitoring.
Fact often was the amp did not audibly hum at all - the mic ( usually a Shure 57 or 58) was picking up supply frequency mag field from the amp's power transformer.
Any dynamic mic's voice coil alone can do this plus 57s & 58s have *unshielded* matching transformers in the handle that do an even better job.
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