Purchased a used Rectoverb.. a few questions.

[Neil27]

Hi there,

I recently purchased a rectoverb 1x12 combo from ebay, it sounds great, however there is a rattling/ringing noise when the amp is turned up a little and played. this noise is also heard when the top of the amp is lightly taped with my finger, Even when the amp is turned off!!

I figured it was a bad tube, I powered off, took out one of the power 6l6's and taped the top, and it seems it was this tube causing the noise.. is this what would be called a microphonic tube?

I guess i have to replace this tube right?, i have heard that both power tubes need to be replaced at once is this true? and what tubes would you recomend that are on the cheaper side? an once in will i need to change the bias?

Another thing that i noticed when opening up the amp was that it look like it has been repaired/moded. The power transformers seem to have residue of some sort on them and dents/scratches. Does it look like cause for concern?

one last thing...is the screw (circled) ment to be sticking out like that?

Sorry about the mass of questions, but this is the first tube amp i have purchased.

Thanks for any input. Is appreciated
Neil

 

[Addictedtokaos]

Dont worry. I just got my first rectoverb earlier this summer. Its also my first tube amp. If you do some searching around Im sure you will find a lot of stupid questions that "I" asked. Ive already blow 3 fuses, fried 2 sets of power tubes, and reversed my reverb tank connections. But these things are built tough. My only suggestion Ive still yet to learn myself is "Always make sure you have your speaker connected." Unless you want to go through tubes and fuses like myself

Does sound like one of your 6L6s is going microphonic. Best way to tell is turn the amp on with your guitar connected and tap the tub with a pencil. if either of them makes noise other than the sound you'd get when taping a glass bottle then they need changing.

And yes, you need to get a matched pair. You cant just replace the one that has the issue.
From the 6L6 tubes i tried, I like Sovteks (im pretty sure they are the same as the Mesa 430 you currently have). Alot of people like JJs. SEDs are nice but for just a basement jammer I cant justify the price.
And Mesa's are fixed bias, they run cool. So unless you change the tube type to EL34s you dont need to change anything.

I believe that glue stuff on the PT is normal I have it too.

My screw is missing. I too would like to know what that is for!?!?! (Terrabang!)

Good luck and Enjoy the Mesa! They are awesome.

 

[Neil27]

Thanks for your reply, Very Informative However i still find the power transformers weird, I dont like that the amp was tampered with.. but hey, what can i do.

If any one else has any info, especially about that screw I would love to know.

Neil.

 

[Blaklynx]

That screw may be an anti-rattle screw or an earth screw. I'm not 100% sure. There was a thread some time ago about 'some screw that sticks out from the chassis' that fetched a lot of talk. I think it had to do with the Lone Star Special amplifier. If you do a search you may find it. If you do find it, it may have no relevance for the rectoverb. So take caution.

Now, I think the screw may extend up to the cabinet and as it presses against the wood it creates pressure, pushing the chassis slightly downward to prevent rattle. I think on the chassis where the screw touches there may be a foil sheet. I'm not sure. If there is a foil sheet, I'm not sure what the relevance is. A ground? I don't know. If the screw does extend up to the cabinet, you don't want to over-tighten it. I think it should be just enough.

Having said that the screw may extend up to the cabinet, it may happen that the screw extends up to the PCB. This is maybe where it acts as a ground. Again, I'm not sure. If it does extend up to the PCB, you really do not want to over-tighten as you may crack the PCB causing some major repair = beware.

Having said all of the above, I could be wrong..... :lol:

As for the tubes, give them a tap as suggested. A decent set are JJ 6L6's if you stick with 6L6's. I've never had trouble with them. ATM, I run Winged C EL34's.

Good luck.


EDIT: As for the transformers, I think you don't have an issue. It may be the way they're finished/painted. I haven't paid attention to mine but I dare say from your photos that's how they're made.

 

[58boogie]

I have the same exact screw sticking out on my rectoverb, so I would not mess with it. Call Mesa if you want an answer and let us know what they say. Other than that, the 430 6l6's are the older version,so they may be original to the amp. With the 440's being the new issue. New Mesa tubes power tubes will only cost you $42 and keep the old ones as a spare set. My transformer also looks similar.

So I would try new power tubes first, since it is a lot cheaper/faster than taking it to a shop and paying $60 or more bench fee to find out you only needed power tubes. I like the mesa tubes and they are an easy find at most guitar centers or you can get them factory direct in a few days.

This thread has some internal pics on page 2 and theories on the screw:
http://forum.grailtone.com/viewtopic.php?f=4&t=25342

 

[Addictedtokaos]

That screw may be an anti-rattle screw or an earth screw. I'm not 100% sure.

LOL :lol:

I do seem to get some extra noise/buzz that may seems ground related. I wonder if that if that has anything to do with it. But if it is a earth screw I should definitely replace it.

 

[Addictedtokaos]

More info on that screw.
http://www.grailtone.com/forum/viewtopic.php?f=4&t=25342

From what I can gather it is a grounding/stabilizing screw for the PC board.

You just want to make sure it is snug.

Now I have to track down what size and type of screw it is since my used Recto didnt have one.

 

[Neil27]

thanks for the replies. I am quite confident that i will just have to change the 6l6's to some new ones for the amp to sound as good as new.

When buying tubes would there be *that* much difference in terms of sound quality? I am looking for the tightest bass at high gain, if it matters.

these are at a good price...http://www.thomann.de/gb/sovtek_roehre_6l6wxt_paar.htm

also these.. http://www.thomann.de/gb/tad_rt212_roehre_6l6gc_duett.htm and

http://www.andertons.co.uk/valves/pid9280/cid594/electroharmonix-6l6-platinum-valves-matched-pair.asp?utm_source=googlebase&utm_medium=pricecomp&utm_campaign=GoogleShopping

also, what is the difference between the red, yellow, green and grey mesa 6l6's tubes?

I will spend a bit more if its really worth it for the tight bass. if not, i may just go for the cheap electroharmonix.

Thanks for any help. Neil

 

[58boogie]

Go with a matched Mesa set to get factory spec tone, color does not matter that much. but yellow or grey seems to be what most new amps I have seen are shipped with. While some can hear a major difference in power tubes, I think that Mesa tubes are a no hassel/ no doubt way to go, and I have not heard a lot of people say that Mesa tubes are not great, even though they may prefer a different brand. If you have a $1600 amp, don't but a set of tubes just to save $10.

I agree with the thinking that power tubes should be clean with max headroom and you should let the preamp tubes do the talking (distortion).

Back on the original topic, I do think that rectoverbs take a vibration beating since they have so much presence and huge bass tone. My rectoverb will shake a whole room, so I can just imagine what the tubes and chassis go through...

 

[Neil27]

are mesa 6l6's just Sovtek 6l6's but rebranded?

 

[Blaklynx]

thanks for the replies. I am quite confident that i will just have to change the 6l6's to some new ones for the amp to sound as good as new.

When buying tubes would there be *that* much difference in terms of sound quality? I am looking for the tightest bass at high gain, if it matters.

these are at a good price...http://www.thomann.de/gb/sovtek_roehre_6l6wxt_paar.htm

also these.. http://www.thomann.de/gb/tad_rt212_roehre_6l6gc_duett.htm and

http://www.andertons.co.uk/valves/pid9280/cid594/electroharmonix-6l6-platinum-valves-matched-pair.asp?utm_source=googlebase&utm_medium=pricecomp&utm_campaign=GoogleShopping

also, what is the difference between the red, yellow, green and grey mesa 6l6's tubes?

I will spend a bit more if its really worth it for the tight bass. if not, i may just go for the cheap electroharmonix.

Thanks for any help. Neil

Different brand tubes will give you slightly different tones. I cannot say which brands will do what to your tone as I've never had the opportunity to try 4~5 brands. In fact, for 6L6's, I've only had the Mesa and JJ's. I replaced the Mesa tubes as I did not know how old they were when I got the amp so I paid no real attention to them. So I went by popular opinion and got the JJ's and I can't complain. Now I run EL34's.....

As for the colour Mesa uses, I've heard two stories:
1. The colours represent a matched bias range or
2. They represent a break up range, ie. how early or late the tubes will break up when the amp is turned up. Somehow, I suspect this is related to bias..... :?

Whichever way, you want the same colour tubes in your amp. You can ask a 3rd party supplier that you want Mesa colour 'green' tubes and they'll give you tubes based on that colour. Make sure that you tell them it's for a Mesa Rectoverb amp. Also, choose a decent supplier, not some dodgy-bros-hardware-store pty ltd...... :lol: When I got my Winged C EL34's I told my supplier I wanted Mesa 'green' coloured tubes. He told me they don't break up too early nor too late... somewhere in the 'middle'. They suit me.

Keep in mind, if you buy Mesa tubes and one fails, you can use the other tube as spare and get another pair the same colour. If one tube of the new pair fails, replace that with the first spare tube to get you out of trouble. You can be fairly confident that no damage will be done. If you try this with 3rd party tubes, you really aren't 100% confident that the tubes will be matched as accurate as Mesa's tubes, thereby running a risk to a degree. In this case, you'd replace both all the time. Anyway, this is what I think. It'll be good to hear from others about this.

To tighten your amp, get a tubescreamer type pedal. There's plenty of info on this site about this topic if you search. Also get an EQ pedal IMO.

Have fun with the amp.

 

[Addictedtokaos]

Mesa 430 STRs = Rebranded Sovteks 6L6WXTs
Mesa 440 STRs = Rebranded TADs GCs

There is a chart somewhere on the interweb that breaks this down.

EDIT:

This is what I was looking for:
http://www.watfordvalves.com/products.asp?id=27

 

[clutch71]

Hi there,

I recently purchased a rectoverb 1x12 combo from ebay, it sounds great, however there is a rattling/ringing noise when the amp is turned up a little and played. this noise is also heard when the top of the amp is lightly taped with my finger, Even when the amp is turned off!!

The noise your describing sounds like preamp noise to me and not power. With power tubes failing you'll most likely experience volume swell or a lack of bass response. I'd pick up a preamp tube and start swapping them out one at time until you find the offending tube. I'd start with V1 as this tube does the most work.

I'm thinking the rattling your hearing when the amp is off is the reverb tank and this is normal.

Be warned...being a combo the power tubes will be subject to vibration from the speaker. This tone will have a shrill glass breaking tone to it. There are tube dampers you can buy to combat theis but only occurs at high volume.

I don't think there are any issues with your power transformer. I can tell from the back that yours is a series 2. Interesting that they moved the choke from the series 1 to series 2. Here's a shot of my old series 1 and you can clearly see the choke in a different location.

 

[domct203]

Mesa 430 STRs = Rebranded Sovteks 6L6WXTs
Mesa 440 STRs = Rebranded TADs GCs

The STR-440 is not a TAD 6L6GC. The TAD is a Black Plate with angled getters. The STR-440 is a grey plate with the traditional flat getter.

The STR-440 looks like a Chinese tube, most likely a Shuguang supplied by Ruby.

Dom

 

[Neil27]

Hi there,

I recently purchased a rectoverb 1x12 combo from ebay, it sounds great, however there is a rattling/ringing noise when the amp is turned up a little and played. this noise is also heard when the top of the amp is lightly taped with my finger, Even when the amp is turned off!!

The noise your describing sounds like preamp noise to me and not power. With power tubes failing you'll most likely experience volume swell or a lack of bass response. I'd pick up a preamp tube and start swapping them out one at time until you find the offending tube. I'd start with V1 as this tube does the most work.

I'm thinking the rattling your hearing when the amp is off is the reverb tank and this is normal.

Be warned...being a combo the power tubes will be subject to vibration from the speaker. This tone will have a shrill glass breaking tone to it. There are tube dampers you can buy to combat theis but only occurs at high volume.

I don't think there are any issues with your power transformer. I can tell from the back that yours is a series 2. Interesting that they moved the choke from the series 1 to series 2. Here's a shot of my old series 1 and you can clearly see the choke in a different location.

I am pretty sure the noise is coming from the power tubes, and also that the noise when i tap the top when turned off, is the same thing as when turned up.

It is a strange 'glass' sound, like you have mentioned (like glass hitting glass). but I am not turning up the amp massively loud, have only played it in my room so far, master volume no more than 3 of 10 i would say at most.

I took out the right side power tube tapped the amp while off and could no longer hear a noise. I have ordered a new set, hopefully that should solve it.

do you think the amp is safe to play as it is?
Also.. what do you mean by a choke?

Thanks.Neil

 

[Blaklynx]

I am pretty sure the noise is coming from the power tubes, and also that the noise when i tap the top when turned off, is the same thing as when turned up.

It is a strange 'glass' sound, like you have mentioned (like glass hitting glass). but I am not turning up the amp massively loud, have only played it in my room so far, master volume no more than 3 of 10 i would say at most.

I took out the right side power tube tapped the amp while off and could no longer hear a noise. I have ordered a new set, hopefully that should solve it.

do you think the amp is safe to play as it is?
Also.. what do you mean by a choke?

Thanks.Neil

Ummmmm........ don't take out the power tube(s) and then switch your amp on! You're asking for trouble. I realise that you're tapping the top of your amp while off to hear any rattles etc., and that you seem to have found a suspect tube applying this method.

With all the tubes in place, turn the amp on, set a reasonable volume and gain and then tap the tubes. You need to hear through the speaker which tube may be microphonic. Try this also if you haven't done so already. Search web for 'microphonic tubes/valves'. There may be something on youtube to give you an idea.

If the amp sounds OK while you're playing, I don't see any harm unless the volume starts to play up on you, ie. starts to swell. In other words, volume goes down then up, or cuts in and out. If it's not doing that, you'll be OK as you don't seem to be pushing your amp hard.

As for the choke, I read about this the other day and for the life of me, I cannot remember exactly what it does :lol:. From memory, when the power supply coverts AC voltage to DC voltage, there is still some unwanted AC frequency (or hum) in the DC signal. The choke is to cancel or 'choke' any unwanted AC frequency (or hum) that may be present in the DC voltage, thereby allowing clean DC voltage through the amp. Google it.

Let us know how you go.

 

[Neil27]

I put new power tubes in and the sound has gone I got some mesa 6l6 greens

When i took one tube out of its packaging it sounded as if something small was loose inside, however i still fitted it and it lights up and sounds fine. Is there anything to worry about there?

 

[Addictedtokaos]

The STR-440 is not a TAD 6L6GC. The TAD is a Black Plate with angled getters. The STR-440 is a grey plate with the traditional flat getter.

The STR-440 looks like a Chinese tube, most likely a Shuguang supplied by Ruby.

Dom

I was just going by what they said on www.watfordvalves.com

"Mesa 6L6GC STR-440 is the latest 6L6GC from the Chinese factory.
This valve replaced the STR-427 as the Chinese made improvements to the valves high voltage stability and sonic clarity.
The valve distorts very easily when driven at moderate levels. This makes it a good valve for blues but it lacks the character and definition of the Winged C Svetlana 6L6GC, Harma 6L6GC-STR
If you want exactly the same valve as the STR-440 then you will need to order the T.A.D 6L6GC-STR."

Believe me, Im not tube expert!