Louis Electric Buster Hum issue

guycp

Last week I got a new Louis Electric Buster 6V6 sent to me.
Firstly I must say that this amp ticks all the right boxes for me. Sounds wonderful at medium and high volume and works great with my Strat and P90 Les Paul R4. I play blues and slide. Great tweedy sound, but firmer and more forward than a regular Tweed Deluxe. Also even with 6V6s, is much louder and bigger sounding when compared to the new Fender Custom 57 tweed deluxe.
Good cleans, clarity, and wonderful natural drive when turned up. Ideal bar or club amp. and light weight!
Everything is right about this amp.

Unfortunately it has a noticeable hum, even on standby, with nothing plugged in.
I am about to send this back, but am very loath to return it simply because it fits what I do better than any other amp that I've tried over the last few years.

So, do any other Louis Electric owners on this forum have any experience or advice about the hum that I'm hearing?
I know quite a few here have had various Louis Electric amps and I think someone took his to a tech to get a hum issue sorted out.

I also noted a couple of other minor issues which are certainly much easier to correct - second normal input jack socket is very stiff and does not 'latch', and rear top back panel vibrates loudly at certain frequencies.

If I'd bought this second hand I'd probably want to hold on to it and get it sorted, but buying new at top of the market, I feel all should be right.

Hum has nothing to do with mains supply in the house, and is noticeable as soon as it's turned on. Gets louder when standby is turned on, but is not noticeably affected by volume control or tone on the amp. Nothing plugged into amp. All valves seated properly.

I am very impressed with Louis Electric amps, and understand that occasionally any amp will show problems due to shipping or handling etc. If I didn't live so far from civilisation, I would try and get a second opinion from an amp tech before sending it back. But living in the far West of Cornwall, getting the amp checked over by someone knowledgeable is difficult.
Dilemma!

RiftAmps

Is it 50hz or 100hz hum? That would help us work out where in the amp the hum is coming from.

There are various downloadable apps for your phone that will help you identify the frequency, I use one called 'FFT Plot' but it's £4.99


Anyway, common causes of hum in new amplifiers:

• Faulty output valve
• Severely mismatched output valves
• Poor ground (possible ground loop)
• Electro-magnetically induced hum
• Faulty filter cap
• Faulty input jack
  

ourmaninthenorth

The big guns are here. 

ICBM

If it does it on standby it must be magnetic coupling from the PT to the OT - assuming it's coming out through the speaker, rather than just a mechanical hum from the PT itself (which could be being acoustically amplified by the chassis and cabinet).

Magnetic coupling is caused by incorrect siting or orientation of one or both transformers. If it's just mechanical hum then it's probably a fault with the PT, although it could just be loose - this can sometimes happen with shipping.

The issue with the second jack socket sounds like it's oriented wrongly so the spring contact hits something as the plug goes in which prevents it opening far enough.

Vibrations and rattles are unfortunately common on combo amps.

When you say 'send it back', do you mean to a UK distributor?

guycp

ICBM

Is that coming from the speaker, or from the chassis/cabinet?

RiftAmps

guycp said:

OOooof that's awful. I measured it at 200Hz with a prominent 2nd harmonic.

Send it back, it's not right.

guycp

The hum seems like its's coming from the chassis, but is also more noticeable from back of the amp, close to the speaker.
Doesn't appear to be amplified by the speaker. It is being collected by a UK distributor tomorrow. I wish I knew how to sort this out myself!

ICBM

guycp said:

The hum seems like its's coming from the chassis, but is also more noticeable from back of the amp, close to the speaker.
Doesn't appear to be amplified by the speaker.

That does sound like it's a faulty or loose power transformer.

guycp said:

It is being collected by a UK distributor tomorrow. I wish I knew how to sort this out myself!

Other than seeing if you can tighten up the mountings, there's not much you can do - if it needs a replacement PT that's a job for the distributor since you would void the warranty if you did it yourself anyway.

mgaw

not the first time an LE amp has had an issue....triple capacitor can? 

RiftAmps

mgaw said:

not the first time an LE amp has had an issue....triple capacitor can? 

Not on this model - the filter pack is on the main board

guycp

Thanks so much everyone for quick diagnosis and knowledge from experts.
Looks like it'll be going back . . .
Will be contacting Uk amp builders soon re new amp.

ICBM

RiftAmps said:

Not on this model - the tomato soup is on the main board

Edited for accuracy...

hotpickups

RiftAmps said:

guycp said:

OOooof that's awful. I measured it at 200Hz with a prominent 2nd harmonic.

Send it back, it's not right.

Wow I never heard that when I demoed one at coda, In fact everyone in that shop would vouch for that becaus I had it near to max. Albeit in the small sound proofed demo room. My poor ears afterwards

merlin

Just as a small bit of input, I have a "Warning" plate on the back of the top panel of my Columbia Reverb. There was a nasty buzz at certain frequencies until I touched it...the screws were loose. Tightened them up, job done. 

I've had issues with both of my Louis amps. The KR12 "motorboated", but only at full gain. They took it back and fixed it. The Columbia's power transformer burnt out. They took it back and fixed it. 

Lebarque

I'm afraid these things can happen with cheap and nasty amps.

ICBM

Sounds like they would do better to pay a bit more attention to building them properly, instead of pointlessly painting over the components on the board.

mburekenge

And the era of Louis Electric being  flavour of the month boutique amp brand on tfb was over. Rip.

dcg

It's a new amp, so back it goes to the retailer.  There was another string on here about a Louis Electric KR12 with problems more or less straight out of the box...looks like this is a quality problem.  Unacceptable at these prices, even though they may sound like the voice of god (and I particularly like the tone of the Buster).

ThePrettyDamned

Hmm, that board looks like one of those amps that's built in that big factory in the States.

What's with the red paint? 

ICBM

ThePrettyDamned said:

What's with the red paint? 

To hide the component values. Whether that's to conceal an original circuit and prevent copying, or to conceal a standard circuit and make it look like it isn't a copy, or just to give an air of magic unicorn dust…

Bearing in mind that it's not that difficult for anyone with a little knowledge and a multimeter to work out what the values are anyway, even if you don't recognise the circuit. For what it's worth it looks like a 5E3 with fixed bias and 6L6s, to me - so a sort of tweed Deluxe/Bassman hybrid.

Whatever the reason, it must add an extra amount of labour and cost for no useful purpose.