1 X 12 Maverick Hum (again)

[plucker]

Hi I have a lovely 1 X 12 Maverick Combo that was all sorted and running well but just lately there is a hum just on the clean channel on both valve and solid state rectifier settings all valves are good (tested by subbing them with known good ones).

Lead channel is fine no hum at all its just on the clean channel anyone any ideas what this could be ie caps or earth checks I could do.

Also Im thinking about changing the stock MC-90 Speaker and was thinking about the Celestion Gold Alnico any one used this in the Maverick or any more ideas please

Thanks

 

[BostonRedSox]

This is either a tube or power supply issue. Always think simple first. More likely than not, the issue is a simple one. Tube amps and have tubes crap out all the time. It is just the nature of tubes as I am sure you are aware of.

First, what channel is the hum present in? All channels? One channel? One mode? Does turning down the gain or treble change this hum? Often, people push their treble and gain too high which will cause lots of microphonics from preamp tubes. This is natural and can even point to a faulty tube if the noise is bad. Do you play loud often? If so, power tubes should be changed out every 6-8 months. Preamp tubes can indefinitely be good, but generally are good for 1.5-2 years. If the hum is present in one channel, most likely it is a preamp tube. Just refer to your manual to see which V slot tube to swap out.

Also, with the amp on and the guitar plugged in, find the channel(s) with the hum. Pull out your instrument cable from the amp. Is the hum still present? If it isn't, chances are the hum was caused from your guitar (poorly grounded, too close to the amp, maybe even the cable itself). Your power source can also be the cause of the hum. I know in my apartment I used to get hum from a series of outlets that also shared many large appliances on the same line. I didn't figure this all out though until this past winter actually. I was sick with the flu and added a space heater, humidifier, and fan up to the outlet via a power strip and ended up tripping the circuit breaker. There was just too much going on in that line, which also used to give my amp massive noise/hum issues. Plugging my amp into a different, separate line, I found that my amp is quiet as can be!

Try to isolate whether it is a tube issue, power issue or guitar/settings issue. Those are the usual suspects, outside of some internal amp defect.

 

[BostonRedSox]

If the hum is apparent in your clean channel, also check the reverb setting on your amp. Reverb picks up everything and amplifies noise. If you have any noise coming from dirty power, it will be amplified with the reverb knob. Also, swap through the pickups on your guitar. If the noise is only apparent from one pup position, chances are the issue is with the guitar, cord, or power supply.

 

[plucker]

Thanks for the quick replies it turned out to be the connector going to the board the big one thats split into a 3 pin and 7 pin I think, the wires are sort of crimped into it one was a little brown with heat on closer look it was not making a good contact, I think its on the ground loop so cleaned it up recrimped a bit and now all quite again

I took photo's ill try and put them on here they may help someone else with a similar problem

Could still do with advice on the speaker must be a few here with vast amounts of knowledge

Thanks again

 

[BostonRedSox]

No problem. I would like to know more about the Celestion Alnico Golds as well. I have a Roadster that I have been contemplating using Alnico speakers with to give its clean and tweed modes more authenticity. Andy from ProGuitarShop has stated that two Celestion Alnico Blues can easily handle 50 watts even though they are rated together as being 30 watts. Just an FYI about the Blues.

 

[plucker]

Anyone help on the speakers ? please

 

[stymie13]

Man, if you could post some pics that would be great. I have a 4x10" Maverick combo and have been through all the same checks: cables, ground, tubes, etc. The local amp tech told me that's just how these amps sound. I absolutely LOVE this amp but would be happier with it if I could quiet the hum. Thanks!!!

 

[Monsta-Tone]

Right on! Good job on finding the problem. I don't have any pictures of a European voltage Mav, but pretty sure you're talking about the white plastic connector on the lower right hand side of the board if you are looking in from the front of the amp.
It looks like a weak spot in design, but I've never actually seen one of these fail.

Man, if you could post some pics that would be great. I have a 4x10" Maverick combo and have been through all the same checks: cables, ground, tubes, etc. The local amp tech told me that's just how these amps sound. I absolutely LOVE this amp but would be happier with it if I could quiet the hum. Thanks!!!

Your local amp tech needs to be fired!
That amp should be dead silent!
My old Maverick would hum like crazy at practice. We practice every Saturday in my Living Room, one of the perks of living in the middle of the forest!
One day, I plugged into a different circuit just to see.
Magically, the hum was gone!

Normally, this would be the way most people find out.
But....I've been an electrician for over 22 years and an amp tech for over 10!
Should have been the 1st or 2nd thing I tried!

Before you reach in your amp's chassis, please discharge the filter caps.
The easiest way is to:
Unplug the amp
Plug a guitar in
Turn the Standby switch to play position
Play the guitar through it for a few minutes with no power

I use a 1K resistor to drain them, but most people don't have one sitting around.

Here is a shot of the connection from the power transformer to the main circuit board:

Here are a couple more of the board:

 

[plucker]

Thanks Monsta-Tone yeah here are the pics of the connector easy to see the hot spot.

By the way it also cured some relay chatter at switch on.

Yes I think you are right maybe a weak spot, I think if it re occurs I will just solder them direct thanks for the reply

 

[94Tremoverb]

Unfortunately the Gold was not available when I had my Maverick 1x12" or I would have tried it, and I think it would have been great. I did try it in my Blue Angel before I sold it, and it sounded fantastic - to me, it sounds very like an "Alnico V30", it's chunkier at the bottom end and a little darker at the top than a Blue. I currently have it in my Tremoverb alongside one of the stock (very well broken-in) V30s, and it's quite similar but just a little brighter and sweeter.

I've also just acquired a Heritage G12H-30 which I've put in a little Traynor YCV20 I picked up - it's spectacularly good, and I think it would suit the Maverick sound as well. Much better than the standard G12H-30, although that's pretty good anyway! It will be OK for power rating if you don't crank the Mav beyond the point of power-stage distortion on the dirty channel, and maybe even then... G12Hs are tough. (But it's an expensive speaker to risk it with, I know.) It's actually quite similar to a more open, clearer Mesa C90, which I tried in the Traynor before it - and which sounded good, but is overkill for a 20W amp and I could more usefully use it for something else...

 

[stymie13]

Great photos guys. Thanks a lot for taking the time to post. I'll check mine out and make sure the connector and pins are good. I don't play my Mav much at all right now due to the current project I'm working in. Seems a shame to let such an amazing amp just collect dust but I LOVE it and can't bring myself to part with it.

 

[94Tremoverb]

I really dislike the use of push-connectors like that in an amp. That sort of overheating from poor contact in the connector is fairly common (as well as occasional open-circuit failures). Something you expect to see in a Behringer rather than a Mesa...

If you can be bothered, it's worth removing the whole thing and soldering the wires directly into the PCB. I didn't have my Maverick long enough to get around to it though.