guidothepimmp
Hi all,
I touched on this in the TS808 thread but thought I'd ask in a separate thread. For all you tube amp owners, how noisy does your amp get on the overdrive channel?
I find that whether my gain is from 3 upwards and the master vol goes anywhere from 2 up, it gets that irritating buzz/ hum , you all know it, like when you have a distortion pedal on with the gain and level on high for both.
is this quite normal for tube amps? my clean channel is sooo quiet, its just my gain that drives me nuts. All my guitars are properly grounded, it is definitely originating frm the amp. That said, I know SS amps backwards but am not to valve tech savvy,
so for all you amp whizzes, does this sound normal to you for a valve amp, or should i let a tech have a look at it? I have never heard other valve amps to make my own mind up so im at a loss a bit...
thoughts? any mods that can be made? caps? transformers? valve changes? I have TAD's in there at the mo... good tubes? average?
Thanks
Ray
I'm waiting for Matta and Fritz to sort out Fritz' Laney Cub (pilot light and hum) and then I'll check if I can take a crack at it. But they taking so long to get to it , hey!
RobK
I'm waiting to see what happens too, as my Laney also hums and has the same light problem. However, I've noticed something funny abou the light. It seems to go off on its own when tha amp is sitting idle. It's like the thing goes into standby or something. Doesn't come out of it, though. Going to time how long it takes to go off and check whether it does it while I'm playing too, just to see if it's a random thing or not. Weird
Ray
No sheeez, mine gives a flicker when I turn it on. then it flickers every now and again when I'm playing. the flickers again when I turn it off. I am sure it is just something loose that needs fixing but honestly I'm a bit nervous to open up and the light isnt the most serious issue. the humming is.
FatBoy
We will be tackling my Cub next Monday, well matta will be doing all the work, I'm just gonna sit there and pretend that I know what he is talking about. Will keep you guys posted!
RobK
Been watching this thing for over half an hour now and it still hasn't gone off. Blerrie typical ?
As far as the hum/buzz goes, I don't turn it up loud enough to hear it and I use a boss blues driver to add a bit of distortion at the quieter volume. Works ok for me for now.
Gearhead
Afaik the hum gets into your output through one or more of the following:
- stray EM waves from the transformers being picked up by small signal wiring;
- ditto, from the heater wiring;
- ditto, from the power wiring;
- improperly grounded heater wires cause current fluctuations inside the tube;
- the noise in your power supply is amplified along with the signal.
So the solutions are simple as well:
- change all the small signal wiring to coaxial and ground the sleeves on one end;
- check your power supply for leaky caps, or bypass big cans with smaller ones or even put in a choke;
- put grounded steel plates between parts with unshielded wires (like around pots, tubes and turret boards) and em sources like trannies and heater wires;
- make sure heater and power wires are properly twisted;
- make sure you don't run signal wires along with heater and power wires;
- put metal sleeves around the heater wires.
Since I am no tube guru I'm sure I have missed a few points here.
The other thing to consider is that you mention it is only audible in the gain channel. This will always be the case since it abviously has more gain to amplify the noise. Having said that, you might want to focus on the wiring around your gain channel.
inflames
Well if you live in SA then you should know of our "dirty" power.
Depends on where you live as well. Tube amps are very much affected by dirty power.
The hum or fizz effect will be a possible effect of dirty power.
One piece of advice would be to get a power conditioner. I personally have my eye on a Furman.
I have heard stories where guys played gigs with tons of hum at a certain venue. Once they hooked up a power conditioner there troubles were gone!
Just my 2c worth ?
Wizard
Both of my amplifiers are hum free while in Bothners ... but acquire some humming characteristics in my house.
"The house that hums"
Could be Frank Zappa lyrics
inflames
Both of my amplifiers are hum free while in Bothners ... but acquire some humming characteristics in my house
Are you sure that it was normal power? I'm pretty sure that the big boys do some power conditioning in store. I might be wrong :-\
RobK
It could very well be power. It could also be my guitars, who knows. At the moment it isn't bothering me, and if I crank the amp up, I'll soon be deaf enough for it to not bother me too ?
I'm just curious to see an expert opinion.
Gearheads suggestions sound good to me, though I won't be touching anything inside the amp because all the solutions attempted by me will end up with a BZZZZZTTTT!!!! and the smell of something burning ?
Wizard
I got a new cable.
A Fender "Vintage Voltage".
Since then things have been much better.
The tech suggested (rightly or wrongly) that my cable might be faulty and be picking up hum from light dimmer switches in the house.
It's a cool cable anyway ?
Manfred-Klose
What is hum? ?
for a long time a battled with hum because i did not understand what it was, i took me lots of posts and questions to be totally be hum-free and.
1.Get a power conditioner for your amp(which by the way protects your amp from being damaged)
2.Get your guitar shielded inside with copper foil(some vintage guys argue that it affects the tone)
3.Get a good quality cable with good connectors(this is common sense)
4.If you got a pedal infront of tube amp to boost gain, get a good and clean power supply for it, or something that cleans up the power.
........sure i do get a little bit of hum when my amp is crancked, but hey thats cool.
aja
RobK wroteall the solutions attempted by me will end up with a BZZZZZTTTT!!!! and the smell of something burning ?
That means your hair's on fire...
matta
Gearhead pointed out many of the problems above, many not that plausible in a SMALL amp to implement, but some are.
I find that some of the BIGGEST problems with the newer PCB amps are poor layouts, poor dressing/implementation of the heater wiring, poor filtering of the power supply, which in turn dumps all that ripple noise into the circuit and lastly poor mechanical layout. On MOST of the Chinese amps (Laney, Fender, Epiphone etc) the power transformer is WAY too close of the OT... on the Champion 600 you can PULL the tubes and turn the amp on and still here the hum that is radiated from the power trafo into the OT.
Laney were gracious enough to send me the schematics for the Cub 8 and Cub 10 and the implementation of the indicator lamp isn't great... it uses an LED in parallel with a power diode across the filament winding to rectify it to DC, problem is that if the forward-biasing isn't set correctly or fluctuates it will cause the LED to stop illuminating... They have reported it to the Laney Tech Department, but not sure there is any remedy/quick fix.
What I would do it REPLACE the lamp with an AC lamp with an incandescent bulb, which is how ALL the vintage Fender and many boutique amps are wired. I'm not sure one can FIT a lamp into the chassis, I'll have to get back to you on that when I look into Fritz's amp on Monday.
There is also a HUM ADJUST pot on the heater lines INSIDE the amp, I will adjust this in Fritz's amp and see how much of a difference it makes...
The circuit is quite interesting, it isn't a Champ Clone, it has a bunch of mods which tend to yield the tamer break-up that I heard when I played the amp... but with a couple nips and tucks one can modify it into a 5F1 type circuit.
The filtering is done by a solitary 100uF cap, too low for my liking, another area we can beef up, prob part of the contribution to the hum problems, we can also convert the heaters to DC to make it even quieter, like I do on the Champ 600 and look are how they have run the heaters.
Lastly, RE hum in valve amps, there is NORMAL hum and ABNORMAL hum, turn on any 30-100W amp and you will hear a hum, that is the power transformer, sometime it is mechanical, actaully vibrating against the chassis, other times it is radiated EMF, some hum is to be expected, but you need to dicern between good and bad hum...
Cheers
Matt
TomCat
matta wrote
but you need to discern between good and bad hum...
? ?....Ahum......I like that...... 8) 8)
matta
Well it is the truth... there is a point of diminishing returns. A valve amp is going to be noisier, generally, than a solid state amp, the thermionic noise ALONE is WAY louder than solid state... part of the reason we moved over, quieter, easier to maintain, cheap to build... I actually feel great when I turn on my old AC30 or Bandmaster and hear the white noise come through the speakers with the faint sound of radiated EMF in the output path... but once I hit a chord and all hell breaks loose I know that any floor noise from the amp with be drowned out by my terrible playing ?
For studio amps, esp. low wattage variants you need DC heaters or at least pay critical attention to the heater wiring, beef up the power supply and a couple general all round tweaks to lower ac hum, but that is for critical applications.
Matt
TomCat wrote
matta wrote
but you need to discern between good and bad hum...
? ?....Ahum......I like that...... 8) 8)
RobK
I don't mind hum, in fact I think it sounds cool when you power up something like an amp and there a bit of hum there - gives the impression of serious power/volume coming up ?
Mine doesn't hum, though, it buzzes, and it seems to only do it when the guitar is plugged is which is leading me to think it's the electronics on the guitars themselves(2 different guitars). Don't think it's the cables as I've tried three different ones with the same result.
The light thing I'm not too worried about, and as it turns out it seems to be a random thing. Also, the light doesn't go out completely. On the Cub 10 you can open the light housing and you'll still see the 4 little led's glowing softly.
Thanks Matt for taking the time to look through the circuits and give us your opinions. I look forward to more once you've had a chance to open and work on one.
guidothepimmp
yaw! so i'm clearly not alone in this...
Thanks for the suggestions folks, i'll certainly look into a power conditioner.
Matt, ever had a look at the guts of a LC30 MKii laney? I was interested to read what you wrote about the cubs, didnt realise they were made in China. Mine says made in UK?! Just wondering what the quality of the circuitry is like in these?
I understand that there may be more noise out of a tube amp, I guess what I was getting at was, is my hum more than normal or the expected amount on a regular gai channel.
I am aware of the "dirty" power phenomenon too. Also with the power supplies for pedals. Regular power supplies are waaaayyyyy noisier than the actual pedal supplies.
Think im going to look for a power conditioner. Thanks folks
matta
Hey Guido,
Nope, never looked into a LC30. RE being made in China... to be honest there are amps made in china that re BETTER quality than many of the high volume production amps made in the USA/China... to assemble Stateside/UK you need to lower costs because labour is more expensive... so first thing to go are quality components, circuit boards end up with traces that break if you just stare at them wrong... no silkscreen on the PCB's... some of the production amps I've worked on just scare me with their poor build quality. This is not to say the Chinese don't get away with murder either... lets just say that there is a reason a handmade, point to point assembled amp costs what it costs for a reason... they just seem really expensive when you compare it to the 'cheap' stuff, but in a different league.
That is why I continue to preach buy an old amp form the 50's/60's/70's and restore it, it will serve you MUCH better, is easier to repair/fix and will last longer... either that or if you can afford it support your local amp builder today and revolt against the solid state revolution (I actually have that on a T-Shirt!).
Ok, one last thing on power filtering... it fixes a symptom NOT the cause... I understand that in some cases it is impractical to fix the cause, i.e gigging in a club with poor line voltage/grounding scheme's etc, but sometimes the fixes can be made for less than the cost of the filter/conditioner device and will give you clean power through out your house, not just the socket(s) on the filter/conditioner.
Cheers
Matt
guidothepimmp wrote
yaw! so i'm clearly not alone in this...
Thanks for the suggestions folks, i'll certainly look into a power conditioner.
Matt, ever had a look at the guts of a LC30 MKii laney? I was interested to read what you wrote about the cubs, didnt realise they were made in China. Mine says made in UK?! Just wondering what the quality of the circuitry is like in these?
I understand that there may be more noise out of a tube amp, I guess what I was getting at was, is my hum more than normal or the expected amount on a regular gai channel.
I am aware of the "dirty" power phenomenon too. Also with the power supplies for pedals. Regular power supplies are waaaayyyyy noisier than the actual pedal supplies.
Think im going to look for a power conditioner. Thanks folks
