Lack of bass en dual rect

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atticus_21

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Hi, I’m new with the mesa dual rectifier sound
I bought this amp but I felt a little disappointed with the bass sound. I thought it would be more “powerful” in therms of Bass. Even with max bass in the knob.
Is that normal??
Im from Chile
This is my amp.
 
What kind of power tubes are in it? EL34 tubes have more mid response and less bass response when compared to 6L6GC tubes, and a different tonal profile. If you want big bass from a Rectifier, IMHO you need those 6L6GC tubes.
 
I would agree with tbonesullivan on the tubes. I stated the maintenance thing as I had lost all bass on my Roadster a while back. Turns out it was from removing the tube shields too many times from tube rolling and not pulling the chassis out. Trying to get the tube shields in some of the spots was tricky. When you struggle to get the shields back on, that is when you start dropping aluminum from the shields and the chassis (that is made of aluminum as well).
 
What kind of power tubes are in it? EL34 tubes have more mid response and less bass response when compared to 6L6GC tubes, and a different tonal profile. If you want big bass from a Rectifier, IMHO you need those 6L6GC tubes.
6L6GC
 
Gain - 12 o'clock
Treble - 0
Mids - 9 o'clock
Bass - 2-3 o'clock
Presence - to taste

Clean Boost ( w/ SD-1 or Tubesscreamer )

Pummel through V30 cab.

Enjoy the best Rectifier tones IMO
 
Hi, I’m new with the mesa dual rectifier sound
I bought this amp but I felt a little disappointed with the bass sound. I thought it would be more “powerful” in therms of Bass. Even with max bass in the knob.
Is that normal??
Im from Chile
This is my amp.
Welcome to the forum.

I’m guessing this is a used amp? If yes you should at the least put in new power tubes, 6L6GC.

What model Dual Rectifier is this? 2-channel? 3-channel 100W? 3-channel multi-watt?

What kind of cabinet are you using? How many speakers does it have? Open-back or closed-back? What brand/type of speakers?

Lastly, what guitar and pickups are you using?

Dom
 
First question, do you have the user manual for the amp? That may be helpful in dialing in the amp.

If the amp does not have the sound, it could be related to a few things. Mostly with the preamp tubes. If the V3 or V4 tubes have been used for some time, the tone will change.

Also if this was a used amp, it could be due for some cleaning. You need to remove the chassis from the head shell to do this. It is also helpful if you have access to compressed air.

things you will need:
Acetone, in a can or even nail polish remover will work.
Small amount of silicon oil
Q-tips (small cotton swabs on a paper stick).
Compressed air from an air compressor or from a can of air used for cleaning computers.

After you remove the chassis, placed it with the tubes facing up onto a flat surface, Remove all of the tube shields, followed by the preamp tubes. Keep them sorted in the position you removed them.

Look at the tube shields first, it should have a black rubber o-ring. It if is silver in color, that is aluminum dust, you can clean that off with some oil on a paper towel or cloth. WD-40 or any silicon based oil will work. Remove the o-ring to clean them and place them back on to the shields.

The next thing to look at is the area around each preamp tube socket. If you see any metallic dust on the PCB around the socket, that is why the bass is not present, I had this issue with the Roadster not too long ago.

Take a Q-tip and saturate the one end in acetone. You will need to collect as much of the aluminum dust around the tube socket as possible. No rubbing needed, just press the Q-tip down onto the area, if you can move it ok but try not to strip the cotton on the pins and leads of the components poking through the PCB.

Do this around all of the preamp sockets.

When you have cleaned up as much as you can using the Q-tips, it is time to use compressed air.

The Best is from an air compressor and a spray nozzle, even an air brush would work if it is small enough. The trick is to disperse the left over dust with the force of the air. Try to do this with the chassis on its side. Compressed air in a can may result in liquid coming out that will frost up on the PCB surface, it should evaporate. Try not to pool too much fluids on the Board surface. Why I recommend compressed are from a compressor but it will do the trick. Do not worry about the liquid from the compressed air can, it is not conductive. I have used that to chill active parts while they were operating and conducting current. However, the trick is to disperse as much of the dust that has accumulated from many tube changes or removal of the tube shields. Getting as much up with an acetone dipped Q-tip will help remove most of it. Do not use alcohol as that will not fully evaporate and may leave behind a residue.

Put the preamp tube back in and see if that fixed the issue. If not, it may be due for some new preamp tubes.

Had similar issue with the Royal Atlantic too, That trick fixed the problem with lack of tone or gain.
Why would anyone put acetone around anything plastic... it literally dissolves (some kinds of) plastic.

You don't need any of this. All you need is a blob of blue tack or Power Tack and just dab it on and pull it off. Hell, you could even use masking tape to pick up loose debris. Acetone is not ideal. Compressed air is not ideal as it'll just blow the same crud everywhere else.
 
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Why would anyone put acetone around anything plastic...

You don't need any of this. All you need is a blob of blue tack or Power Tack and just dab it on and pull it off. Hell, you could even use masking tape to pick up loose debris. Acetone is not ideal. Compressed air is not ideal as it'll just blow the same crud everywhere else.
Thank you for your comments. I was wrong to suggest it.
 
The advantage with acetone is that it will flash off quickly, but yes you don’t want it to get onto anything plastic.

Denatured alcohol would work in a situation like this, as well as the blue tack and masking tape.

Dom
 
As for plastics and acetone, styrene and PVC are susceptible to damage, Even denatured alcohol can result in damage as a blend with some petroleum distillates, it is not just pure ethanol. Isopropyl alcohol that is bought in stores or pharmacies is diluted with water. You need something that is closer to 75%. Ether will clean PCB surfaces too. Typical solutions for PCB cleaning is a blend of denatured alcohol and acetone.

The trick is not to saturate the surface or to use it on the tube socket, that is not the area of concern, just the perimeter around it, mostly the component leads of the parts on the other side that comprise of the gain stage circuits. I am assuming that Mesa uses a Rosin flux or they may be using an acidic no-clean flux when they process the boards through the wave solder. I had found with the two amps that had this aluminum dust from getting the tube shields in place will cause signal loss.

Tried cleaning it up without any fluids, it was a no go. The dust was stuck to the board surface. A small cotton swab on a stick (Q-tip) did help to pick up the dust as well as break it free from the surface. Also it is easier to get the Q-tip under the hook of the component leads.

I do not have blue tack. Perhaps that would work out well. Doubt you can work with it in the narrow area but if there is a will there will be a way. Waud it around a stick, if it does not fall off, it may work. I have tried tape of different types, blue painters tape as well as electrical tape, I did not try the rubber tape though, that would work I believe, it is tacky but not a puddy. The issue is the surface to be cleaned, it is not flat as it is laden with sharp cut leads that were bent over during the component insertion process of the PCB assembly. Even a Q-tip will get shredded from those leads. Heck I even tried a small brush that would fit, did not work. Compressed air by itself, did not remove the bulk of the contaminants. Not even sure why I bother to write this,

Go ahead and crap all over my comments, I do not care. As I said before, I will no longer suggest anything that may be of help. I did delete my post due to getting pissed off, however, there was that what if-someone used a liberal amount of fluids to clean the board, not a good thing. I will go back to being silent and not bother to participate.

The point is, if there is any aluminum dust or other contaminants surrounding the socket on the board surface, that contamination if it is metallic will result in signal loss. If the board surface is clean, then no worries, change the tube and that should correct the problem.
 
I watch a lot of amp repair videos, and all that most use on the video is isopropyl. I think naptha would also be good, though definitely not as "harmless" as isopropyl in terms of exposure. I mean you could probably also use straight ethanol as well.
 
I use naphtha and denatured alcohol everywhere. The naphtha flashes off nice, and doesn’t hurt guitar finishes and most common materials, but on a PCB I stick to the alcohol as much as I can.

BTW don’t try to clean a Roadster’s face plate with alcohol, well isopropyl at least. I was out of denatured and used isopropyl to clean some junk off the amp and it was taking the screen printing off with just a quick wipe with a q-tip. I started around the knobs and noticed the GAIN printing coming off. I was quite surprised.

Turned out ok in the end, seeing it was the gain for CH’s 3 & 4 I re-labeled it ‘ANGRY’, which inspired me to also relabel the channel masters ‘LOUD’. Turned out to be a great conversation starter at gigs LOL.

IMG_9439.jpeg


Dom
 

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