Dual Rectifier Problem

Hey guys here's the deal:

I have a Mesa Boogie Dual Rec. It is about 2 years old. I read online that you know your tubes are going because your tone will sound muffled/muddy. That is exactly what was happening with my amp.

I brought it to my local guitar shop to have the tubes replaced. I received my amp a couple of days ago. I plug in my guitar and I am experiencing the same muddy/muffled sound. I tried this with multiple cables and different guitars.

Can you guys please help me troubleshoot what causes a muffled/muddy tone? Thank you all very much for all your help.

2yrs in age is getting up there.. how many hrs do you think you have on them?

Did you replace the preamp tubes? They generate most of your tone so they should be looked at first when trying to find problems.

You don't have to buy new tubes just start swapping them one at a time with a tube that's lying around or maybe with V4 or V5 that's in your amp already.


Greg

Did you replace ALL the tubes? Muffled/muddy usually a symptom of power tubes, but you could have a bad preamp tube as well. At the very least I would change V5 (phase inverter) when retubing the power section.

Check EVERYTHING in your setup... FX pedals/racks, all the cabling including speaker wires, try running your guitar straight into the amp, no pedals, nothing in the loop, loop select on Bypass. If it's okay like that, add a piece at a time until you find the offender.

Other things to look at: speaker cable plugged in to the right jacks on amp and cab, batteries in active pickups, blown speakers, check your electricity for adequate voltage and proper ground, batteries/power supplies for FX devices, loose wires inside speaker cabinets, tubes could still be a problem...just because they're new doesn't mean they are good.

yes all of the tubes were replaced.

someone on another form said, "could be your caps going bad". What are those? What does that mean? What do they do? Any comments would be appreciated.

Put the old tubes back in and see if the amp sounds the same.



Greg

because i had it done at my local guitar shop i don't know if he still has the old tubes.

I HIGHLY doubt you have a bad cap (capacitor) in a 2-year-old amp. Anything is possible, but the caps usually last 10-20 years and often longer.

Don't pay a tech to change your tubes...its as easy as changing a light bulb. Mesa amps don't require rebiasing, so as long as you go with tubes rated to work in Mesa amps its just plug 'em in and go. Plus you can keep your old tubes for spares (assuming they are still good).

If the caps were going bad [which I have seen recently in a couple of newer Dual Recs] the clean channel often times will tend to have a fuzzy
non pleasant strange distortion following the notes when played. You will also notice it on the distortion channels, but you may have to listen closer to catch it depending on how far gone the caps may be.
Is the amp noisy [like a rushing roaring sound] when just sitting with nothing plugged into the input with the amp off standby [ready to play]??
Does the amp sound like this outside of your home [at any other location]?
What power tubes are you using [EL34 or 6L6]? Is the bias switch set correctly?

Ok so call me crazy, but I would be questioning if they actually changed the tubes or not....I don't trust guitar center personally, I think they take advantage of people who they think they can. I see them screw so many people out of good money on trades, and I see how they sill people things that aren't right for them.

Guitar Center sales people work on commission. They don't sell the right stuff, they sell the highest profit margin stuff to get PAID at the end of the day. Someone once told me their average turnover is 90 days for a sales person. Most of them have no clue what it is you're asking for, so how can they know what to sell you to start with...LOL!!!! I've never met one that had any kind of technical expertise to help diagnose a problem. They probably did change the tubes, just to make the sale on the new ones.
Trade ins are a whole other issue with them. They have to call a centralized 'buyer' and get approval to take a piece on trade, and that person sets what GC is willing to give you for the trade allowance. Its usually about half of what market value is [from experience]. They want to double their money when they sell it. Trading in is never a good idea, you will lose every time.
Back to the problem at hand...
Does the #1 channel sound this way as well as the #2 and #3?
You said the amp was about 2 years old. Could it have been an older one that just never sold before? Mesa did make some design changes in the duals. It would help to know which circuit we're dealing with. Many things can effect the audio path, not just simple tubes. A bad cable, a dirty pot, etc..

I just want to clear some things up about guitar center. Now I'm not saying this is true for every guitar center, just the one I worked at. I would say the majority of the people I worked with while I worked there knew a decent amout about what they sold. Some were weaker than others, but for the most part they were good. Nearly all of them but maybe three or four were dedicated to getting people the best solution to what they needed. The people that were not talked a good game and were probably ex-drug dealers. I went to college for an AAS in production, and am very knowledgeable in studio gear and synths. I could talk for hours about the pro's and con's of recording systems and synthesis methods.

There are many times they will sell things below advertised price. I still get good deals because I worked there and I have a few people I talk with. All you have to do is ask. But there is a catch, they can only go so far with prices. A mesa amp has maybe a 50 dollar markup, they are not going to lose money to sell you an amp unless your buying a ****-ton of other stuff. Then they'll take the price off the other stuff. But things like cables, effect pedals, some guitars, and a few amps have a pretty high mark-up, and if your get to know your salesperson, he may mark it down.

As far as re-tubing your amp goes, again I can't comment on the store in your area, but the one I worked at did NO in house repairs or servicing. It just wasn't done, we sent them out to one of three businesses in the area depending on what it is. I'm sure the one near you does the same thing.

And trade in's are always a touchy subject with people. They don't want to feel like their getting screwed but really. How much do you seriously think your three channel dual rectifier is on resale? If you think it's going to sell for $1,000 dollars, why would Guitar Center give you $1,000 and make no money off it? They're going to give you the best deal they can give you, and have it be financially sound. I had a friend get into a tax problem and have to sell his tremoverb. Guitar center bought it for 1000, and sold it for 1200. Thats a fair deal for both people. There is no incentive to buy your wah for 60 dollars, or your line 6 spider for 300 dollars. They won't sell that well, if at all. And the final choice for trade-ins is made by the store manager, not some guy on the phone. If your not getting the deal you want, ask to talk with the store manager and ask him why. They will tell you. The store manager that I worked with was a dick, but he would never lie a customer or screw a customer over. It's bad business.

DTheater512 - What are your settings? What type of guitar/pick-ups are you using? What cabinet are you using? Are you running any effects? If so what and how are you running them? If so, have you removed them from the signal path to see if that might be the problem?

ok guys so here is the deal...

I only get a muffled sound when I plug in my delay into my fx loop. I came home and set up my rig like I always do. I found that I was still having that muffled sound. So I then unplugged everything and went straight into the amp and it was fine. So by doing some process of elimination I found out that it was my fx loop. Could this mean that maybe V4 (the preamp tube for FX send and FX return) may still be bad?

Any thoughts or comments? Thanks

Could be the V4 preamp tube, but more likely you are overdriving the input on your delay. What are your settings, specifically Channel Masters and FX Send? Try FX Send at around 1:00-1:30, Output 11:00+, bring up volume gradually with Channel Masters until you get it where you want it. This way you will be sending less signal thru the loop.

What dealy are you using?? I know for fact that the LINE6 dealy pedal [the big one DL4] will NOT work in the fx loop correctly.
There will be a level mismatch with this unit. Its only designed to work at instrument level. Even on the front end of the
amp it caused a big tone change. It muffled the signal badly.
Use a quality delay, TC Electronic, Eventide, etc...