Diode Noise

[cnumb44]

My LSC sounds really good and quiet, but the other day I noticed a slight buzz when I am in silicon diode mode. Just sounds like a little bee, not really obnoxious. It is there when I am in 100W mode on either channel or, in 50W mode with Silicon selected. When I am in rectifier mode all I get is a very slight amp hum. Of course, that means I am only able to play in 50W mode to not hear the little buzz.

Is this just me being too picky? The nearest mesa repair place to me is about 1.5 to 2 hours away, so it isn't any easy commute and I'd have to leave it for a while.

I did order a power conditioner to see if that will help. The power here can be a bit noisy, or so I've discovered.

Just wanted to know if anyone else has that some noise and if it is considered normal. I'll probably bother Mesa tomorrow just to talk to them. They are very good at calling back.

 

[old-guy]

Jerry,
I have the LSC 1x12. I've got the same thing. I usually play in 50w, tweed power w/ tube rectifier. The other day I switched to full 50w and 100w silicone diode and I got this slight buzz. I was sitting there saying "now what the hell is causing that?" Do me a favor, please let me know how you make out with the power conditioner. You're right it's not "huge" but I think it's annoying. I'm gonna take it off tweed, play full 50w / 100w and leave it on diode for a week or two and see what happens. I know I'm "no help" but at least you know you're not alone with the "buzz".

I'm glad you brought it up. (I thought it was just me)

Bob

 

[old-guy]

Jerry,
Well, here goes my typical "bad luck." I have to call Mesa today.
My buzz has now turned into a full-time hum. Tweed, full, 50w, 100w, silicone diode, tube rec., it doesn't matter. The hum increases even more if I bypass the loop. And we're not talking "loud volume," but definitely a pretty loud hum. (Never had it before) I tried plugging into a different circuit in my house that's 100% clean with nothing on it but the amp.
Didn't help.
Like I said I'm gonna call Mesa today. Luckily I own a pickup (truck) and there's a factory authorized sevice center about 20 minutes from me, so if it has to go it's no big deal. But I'm kind of hoping it's the tubes or something simple. (I just don't feel like lugging this thing around) I'll let you know how I make out.

Bob

 

[jbird]

I'm gonna guess it's nothing to do with the rectifiers.

 

[old-guy]

Well Boys .................................. I called Mesa today and talked with Chris. He talked me through different things over the phone, The bottom line ------------ "well Bob, you're gonna have to take the amp to a service center. I can determin that the problem is somewhere in the power section and it's not the tubes. I just can't say exactly what it is but there is a problem."

So, I took the amp to the sevice center this afternoon. 10 minutes from my house and these guys ARE PROFESSIONAL. Great place, They even sat a talked with me about Mesa's amps, other amps, tube amps, solid state amps, real interesting stuff. Now at least I'm not worried about my amp being in good hands. The only down side is 2 to 3 weeks until I get it back. THAT SUCKS!!!!!!!!!!! Guess I'm going "acoustic" for a while.

I think that all you guys that own the LSS wished this on me! I bet you're all sitting back laughing saying "I always knew the Special was a better amp." Sure, that's it, go ahead, kick me when I'm down. Honestly, if I could afford it I'd like to own both.

As soon as I find out what was wrong with it, I'll post it on the board.

Hey Jerry, how'd you make out with your "buzzing diode?"

Thanks guys!
Bob

 

[cnumb44]

I just shipped my amp back to Mesa on Saturday. There are no close by techs here in Connecticut and the one that is closest is awful slow. My experience was almost word for word for what happened to you. Must be the closeness of Mars or something.

The silicon diode mode got so obnoxious that I couldn't even use it. The MB customer support was very helpful and there is a part of me that actually likes having it back at the factory - it just costs me the shipping, but the time sounds about the same as if I took it to a local tech - it'll be 3 weeks.

Just out of curiosity, what was your tech's opinion of Mesa amps?

I think they have good build quality compared to Marshalls and Fenders I have seen. The best built amp I ever saw/owned was an Aiken. It was also quiet as anything. Talk about attention to detail and dedication to the tube amp cause! I wanted a channel switcher with a clean and drive channel so that is why I went to the LSC. The Aiken 2 channel Sabre was a head only and about $2500.

 

[old-guy]

Hey Jerry!
Sorry to hear that you had to send your amp back to Mesa.
I do agree with you about having "peace of mind" with sending the amp back to them. I "should" have mine back by Monday, Nov.7th. I took it to a place called Davidson Electronics. If I had gotten a "bad vibe" when I walked in I'd be doing the same as you. There is no other place around here to take it. If I'm not happy for any reason when it comes back, then I'm going to "plan B", back to MB. But honestly they really did seem to know their stuff, very professional, the building was large and modern, very clean. The first thing that they did was check the cabinet. I laughed and said "It's perfect, there's not a mark or scratch on it including the bottom." They smiled. (yeah, I'm neurotic about my gear)
As far as their opinion of Mesa's amps. Their tech "Pat" the guy that does all the work on MB products really likes them. He really loves the clean tone of the LSC. As soon as I uncovered the amp and he looked at it he said to me "you gotta be into the clean sound". I said yep, but it's got some great overdrive in channel 2. He also said it was a great concert amp, the tone at higher volumes was fantastic. One of the other techs there didn't like 2 things about MB. He hates the fans and he hates HAVING to use MB tubes for warranty work. But I also got the feeling this guy wasn't crazy about tube amps in general. He talked with me for an hour about "boutique", "vintage" and "modern" tube amps. Whether I ageed with him or not, he was very interesting to listen to, and he did know his stuff about "tube amp history." I think he feels that with all of the research and advances being made with SS amps, that it's just a matter of time before they achieve the "tone" of a tube amp with the dependability of solid state.
Hey, all I know is I GOT NO AMP! When I get it back I'll do a new post and let you know what was wrong and what they did. When yours comes back do the same. We'll compare notes! I don't play out so I have no other amp. It's been 1 1/2 weeks and it's really getting to me.
This REALLY SUCKS!
I hope yours comes "home" soon! Good luck to both of us!

Bob

 

[cnumb44]

Thanks for the update. One good thing is that I have a nice Martin HD28 that is wonderful to play, so at least I am not without a guitar.

It was good to hear the views of the tech's. I know MB is a good manufacturer, but sometimes it is nice to have it reinforced. Since my 2x12 cab is realtively empty right now I took a look at the build quality and was very impressed. If they pay that much attention to the cab, then you've got to think the amp gets a lot of attention.

I will definitely post what I find out from Mesa when they take a look. It will be good to compare notes and see if we had similar issues.

Hope you find a six string outlet in the interim!

 

[old-guy]

So "you" took the chassis out of the cab and shipped it back that way? What an idiot I am. Here I am thinking "man, the amp is so heavy it must have been a fortune in shipping costs." How did the removal go? ****, I would have sent mine back too. Hopefully these guys will be careful with my cabinet. (You know I'm gonna check it out real good when I pick it up)


HD28, now that's one beautiful guitar. The one thing about Martin, you have one now that sounds great, it gets even better as it gets older.
That happens to me my personal favorite. (Martin) Any electronics? Or straight acoustic. If the day comes (extra $$$$$$$) I would love to get one. I'd go just acoustic, there's just something about a guitar with rosewood back and sides, nothing replaces that "sweet sound."
Take good care of it! That's definitely "a keeper for life."

Now we sit and wait .............................................................................
Enjoy your Martin!

 

[cnumb44]

Just the four screws that hold it in. I turned it upside down and set it on an old milk crate. That way I removed the screws and the chasis just rested in place. You have to take one of the pack panels off, but it is made to remove by taking out 6 screws. Unplug the reverb, power and speaker and it just lifts out.

I took the power tubes out (they requested that) and wrapped the chasis in bubble wrap. I tucked some newspaper in the underside where the circuit board is just for safety sake. Wrapped each tube in bubble wrap and put it in a box.

Here's a trick I came up with. I've shipped a few amps and I like to buy some of that stiff pink insulation board that you can get at Home Depot. I cut out a piece that fit in the bottom of the box and then taped the bubble wrapped chasis to it. That keeps it protected from anything breaking through the cardboard and keeps it from shifting during shipping. You can also cut out the styrofoam to easily customize the packing. A 4x8 foot piece costs less than $10 and you can use it for lots of packing.

As far as the HD28 goes - it is pure acoustic. I love the sound and smell of rosewood. It is great to have both electric and acoustic. I am very fortunate.

 

[old-guy]

Thanks for the info. on taking the amp apart and packing it for shipping.

I made a copy of your instructions and put it in with my MB papers just "in case". (1 more week to go)

Thanks
Bob

 

[cnumb44]

I got a call from Rich at Mesa yesterday and do they did the complete test of the amp and found no problem. They did install a change to the grounding that they said will help a little - it was a standard fix or release or whatever they call it. On another note, they also fixed a problem with my reverb.

I'll get the amp back in about 10 days and will let you know how it is.

I've dealt with their customer service guys directly 4 times now and they are, in my mind, the definition of great customer service.

 

[old-guy]

Yo Jerry!

Re: The Fix

"It helped a little." I don't know if I like the way that sounds.
Was your amp nice & quiet when you first got it? Mine was. I guess we'll have to wait and see once you get it back. What are you going to do if you still got "bees?" Did Richard leave you with a "positive outlook" or with a "question mark" as far as the success of the repair. (You know why I'm asking.)

Thanks for the post, much appreciated.

Bob

 

[cnumb44]

I can't fault Mesa's customer service. Rich has been nothing but great while I have had them work on this problem. They did install a grounding fix and tested the amp. In their view it is exhibiting normal noise levels now.

The amp came home a couple of weeks ago and I wanted to live with it for a while before I posted. There is no longer the diode related noise in either channel. There is a little increase in hum when I switch, but that is to be expected.

Channel 2 sounds much better and has what I would call a normal hiss for a high gain amp. You only notice it when the gain/master is way up and you can't stay in the room with the amp that loud!

Channel 1 continues to have a noise problem. With moderate gain and the master approaching 12 o'clock I have what I would call a transformer hum - the kind of hum/buzz you would hear from an electric motor. Passed 12 o'clock it becomes very loud and if I play with a mild attack the noise is louder than the guitar. Again, I hardly ever get to this volume level and around 11 o'clock on the master and lower gain, it is normal noise.

I am told that this is normal for this amp. For $1600 I think the design should be better. I'm thinking through my options right now, but I really like the sound of this amp. I've tried several other similar style amps over the past few weeks (Rivera, Bogner, etc.) and haven't found one that hits the spot the way the LSC does.

I won't post any more on this topic. Thanks,

 

[cnumb44]

So after sending my LSC back to Mesa and having them look at it the noise still persisted on the clean channel, 100W, full power mode. I could not put the master for the channel passed noon because the hum was louder than my guitar. It was frustrating. If I used tweed power at 50W and kept the volume down it sounded OK, but for what I paid I expected it to work.

Just for a little history, just before the problem started I had a power tube go on me. I was using Mesa power tubes and was playing one day when the volume started to lower and a crackling sound happened and then the power went off.

I immediately unplugged from the AC and checked the fuse. It was blown, so I looked at the tubes and sure enough one of the 6L6's was clearly blown - it had black fog inside and the glass had been deformed.

Next day I called Mesa, they verified the bad tube and sent me a replacement. A week or so later I started to notice the sound.

Fast forward to getting the amp back from Mesa and finding that it wasn't really fixed. After living with it for a while and deciding that I liked the amp enough to try and get if fixed. I called Voodoo Amps in Ithaca and looked at their web site. Trace answered a number of my questions and i thought I would take the chance so I sent them the chassis.

It took them about 5 days to get the amp on the bench and they had the problem isolated and fixed in 45 minutes. There was a bad screen grid resistor on one of the power tubes. I talked with Anthony, the tech at Voodoo who did the work, and confirmed that a tube going bad would be the leading cause for the screen grid resistor to get fried.

It seems like Mesa would have been able to find this as fast as anyone, especially since they had it on record that my amp had previously had a bad power tube. They were always very responsive and helpful when I called, so I won't fault them on their attitude. That doesn't cut it for me anymore since I don't think they know how to trouble shoot their own equipment.

The guys at Voodoo work on amps all day and play guitar in bands at night. I think their experience is what made the difference.

While it was there I had them install a bias trim pot so i can put whatever 6L6 tubes I want in the amp. That wasn't a big decision for me since I wan't going to use the warranty from Mesa anymore so voiding it made no difference to me. Setting the bias is something I am comfortable doing and have done on all my amps since I owned a Marshall DSL50.

I love the sound of the LSC. I haven't played a Roadking, but I think the LSC is unlike any other Mesa I have heard and it hits all the tones I want. Now that it is running normal I am re-energized by the tone. It is interesting that since I have had the bias control installed, I feel a bit more freedom to run the amp the way I want to and not being tethered to Mesa tubes and their bias settings. It may be immaterial, but I like to have that bit of control back.

I am back to playing guitar and enjoying the sound of this amp. i guess that means there is a happy ending to all of this!

 

[tele_jas]

What about calling Mesa and letting them know you sent the amp to them for repairs and it didn't get fixed, but you sent it to Voodoo and the isolated the problem and fixed it..... See if Mesa will pay for it? They may not since you had the bias pot installed, but it's worth a shot.

Just a little FYI... I was looking for a good amp to play rock/hard rock/ and country and I had the LS and LSC suggested to me SEVERAL times, but they just didn't have the recto sound I LOVED so I passed on it and tried several other Mesa amps (Tremoverb head, Tremoverb combo, Rectoberb) before getting a Road King. The Road King is the best amp for me to play all those styles and blows away all the others in the rectifier series.... The clean isn't quite the same, some would say it's not as good as the LS series but I really like it. But if you don't need all the other gain options, I'd stick to your LS.

 

[cnumb44]

Tele, thanks for the feedback. I like my LSC. If I ever changed it within the Mesa line, it would be for a Road King. They sound like awesome amps and I love the idea of 4 separate channels. You've got to be able to find your sound (or severla of them) there somewhere.

I was going to write Mesa a note and explain what I did. I hope it improves their support. They obviously take this very seriously, so I am certain they'll have a reaction and improvement.

I like a clean channel to play some country style rock (Wonderful Tonight by Clapton is a good example). That is more of a rhythmic arpegiated type playing. For leads, I really like a bit of a drive, almost blues type sound, so I think the RoadKing would probably be fine for what I like to play around with. I just costs $1000 more than an LSC (although I do see them on e-bay every so often at good prices - and that takes some control not to pull out the plastic!)