Rectoverb combo issue

[donnievaz]

Hi, I'm the pissed/disappointed new owner of an older series 1 Rectoverb combo. I just bought it used, drove a couple of hours into a neighboring state to get it and it has issues. First off, I fully admit that I'm a dumbass for not cranking it up when I tested it out. The kid I bought it from's dad was upstairs and I was trying to be as little a disturbance as possible. STUPID! I got it pretty cheap so I'm not that distraught but it stills sucks to have to deal with this.

Here's the symptoms and what I've done so far. All the symptoms are more noticeable the higher the volume goes. Just for reference, I played a Single Rectifier Solo 50 head at GC yesterday to get a better idea of what this thing should sound like.

1. The clean gets dirty way earlier.
2. At anything higher than bedroom volumes the pushed mode is unusable. It sounds like a maxed out fuzz pedal that cuts out intermittantly.
3. The dirty channel is better but still sounds off.

What I've done:
Swapped power tubes. First I put in a set of JJ's that I had laying around. These seemed to help the dirty channel somewhat but not completely. Next, I ordered a set of TAD 6L6's and had him pick out a set that's compatible with the Mesa as far as current draw thinking that that may be part of the problem. Turned out to be no significant difference from the JJ's. I also swapped a bunch of preamp tubes with no luck. I'm going to try a more scientific approach tonight and do one at a time hoping to eliminate all possibilites. I'm thinking this problem goes beyond tubes.

Has anyone else had the same issues?

Thanks!

 

[MusicManJP6]

Replace the preamp tubes one at a time with KNOWN GOOD tube(s). It sounds like a bad tube IMO. Also make sure none of the pots or jacks are scratchy - including the FX loop mix pot and FX jacks. Might be worth cleaning all pots and jacks with deOXiT. Check the speaker connection too. Good luck!

 

[Jak0lantern01]

I'd say swap the pre-amps also. I have to admit, though, that my Recto combo's cleans are really never all that great, even with fresh tubes. That's why I love my Stiletto.

 

[donnievaz]

Tested all the preamp tubes last night, all good. I did some more fiddling around with the settings and found that the pushed mode problem goes away if I back off of the clean channel master. I was also able to get some half decent tones out of it after playing with all the settings but still feel that something's not right. For one, the clean channel in clean mode is not clean with the gain at anything over about 8:00. This is in comparison to the head I played which stayed clean up through at least 12:00. I know I can't expect Fender Twin cleans out of this thing but it should be a lot better than what I'm getting.

The lead channel sounds pretty bad as well. I did manage to get a pretty good tone out of it in vintage mode with the mid dimed and bass & treble at about 9:00. I wish I had access to a good working model so I could do a real side by side comparison. Any volunteers in the MD DC or Northern VA area? :wink:

 

[Jak0lantern01]

Trust me, I've had similar findings with mine too. The head you mention, was this a 50 or 100 watt head? The 100W would give you more headroom and slightly better cleans. I still think you should try an entirely different set of preamps, like the combo offered from Doug's. It made mine sound a lot nicer. I ran a Eurotubes combo in my recto, no good at all (IMO), even though I hear a lot of peeps like that combo in the Stiletto.

 

[donnievaz]

Trust me, I've had similar findings with mine too. The head you mention, was this a 50 or 100 watt head? The 100W would give you more headroom and slightly better cleans. I still think you should try an entirely different set of preamps, like the combo offered from Doug's. It made mine sound a lot nicer. I ran a Eurotubes combo in my recto, no good at all (IMO), even though I hear a lot of peeps like that combo in the Stiletto.

The head I played was a Single Rectifier Solo 50. I may have to break down and buy a new set of preamp tubes. I was talking to a tech/designer friend of mine last night and he was recommending a bias mod. I may do that anyway but I've got some more basic troubleshooting to do before it gets to that. I have the schematic, so I think I'll pull the chassis when I get some time and give it a quick runthrough in case there's something obvious.

 

[fishyfishfish]

Have you tried a jumper cable in the effects loop? Sounds like the same problem I had with my lonestar.

 

[donnievaz]

Have you tried a jumper cable in the effects loop? Sounds like the same problem I had with my lonestar.

No but I'll give it a shot. I've had that problem before. Most recently with a Laney AOR 30. I doubt that that's what's going on here but will definitely try it, thanks.

 

[donnievaz]

WooHoo!! Fixed it!! Turns out it was a burnt out resistor on the power tube socket board. I was hoping it would be something simple and obvious and sure enough it was. Sounds like a whole new amp. Thanks for all the support and suggestions

 

[musicmasterguitarist]

i have a rectoverb series I also, and have similar issues that you mentioned...

my main complaint with this amp is:
the clean channel isn't as clean as it used to be, as when i first purchased the amp years ago..
the amp seems to have lost something in the tone. it's hard to explain.

but i have replaced tubes...
cleaned sockets..
switched from using the combo 1x12 to using a vox 2x12 spk cab.
i like that much better...

biasing.. i was under the impression that this amp had a fixed bias?
but i am going to recheck the tubes..
especially the power tubes to see where they are at on my tester.

i have a question though, after you had your amp serviced...
now does it produce a really nice clean tone in channel I?

any info. greatly appreciated.
thanks

 

[donnievaz]

biasing.. i was under the impression that this amp had a fixed bias?
but i am going to recheck the tubes..
especially the power tubes to see where they are at on my tester.

i have a question though, after you had your amp serviced...
now does it produce a really nice clean tone in channel I?

any info. greatly appreciated.
thanks

There are 3 bias methods.

1. Cathode bias. Requires no adjustment or tube choices, just pop new tubes in and go. Most single ended Class A amps use this.

2. Fixed adjustable bias. Majority of the amps out there use this. NOT Mesa though. Bias has to be set when changing output tubes.

3. Fixed non adjustable bias. Mesa uses this. The tubes must have a current draw that falls within the range set by the bias resistor(s) used in the design of the amp. Mesa branded tubes have already been sorted out for this but you don't have to use them. If you tell your tube dealer which amp they're for, they will choose the correct tubes for you. This is only true if you use a good dealer such as KNOS, or Eurotubes. I'm sure there are others but those are 2 I've dealt with.

My amp: When I fixed my amp, EVERYTHING improved vastly including the cleans. In my case I got lucky. One of the screen resistors was burned up. If you look inside the chassis you'll see a small separate board about 1"x4". There are two 1K 2watt resistors on that board. Check both with an ohmmeter and make sure that they're at or very close to 1K. DO NOT DO THIS IF YOU HAVE NO EXPERIENCE WORKING ON AMPS. YOU CAN DIE!

 

[donnievaz]

OK, I took my amp in to my friends shop on Friday. We bumped up both screen resistors to 1K 5W, and did a bias mod. All I can say is WOW! This amp sounds 1000x better than when I first got it. It sounded much better after fixing the screen resistors but the ability to set the bias is the icing on the cake. The amp is just much warmer and more musical to my ears with the bias properly set. After this, I really have to wonder what the hell they were thinking when they designed it the way they did.

 

[pokerrules47]

They are designed to last a long time with the tubes you buy from mesa boogie. Non-technical guys love the fact that for the most part, boogies are bullet proof. To get decent tone out of an amp, you have to build in adjust-ability. Doing this creates a situation where you aren't going to be as reliable as you would want. Mesa found the middle ground. They had to have some constants, to keep the amps as reliable as possible, so they setup a fixed bias platform that has worked for them quite well.

That being said, the fixed bias platform isn't for everyone. So, more technical people modify the amp to allow adjustments to the bias. This comes with some risks (i.e. blowing tubes and what not) but if you know what you are doing, you can possibly get a better sound out of the amp.

 

[musicmasterguitarist]

thanks for the input.
i am not currently using this amp anymore.
the music my band covers requires more clean tones than anything.
although the rectoverb amp gets great overdriven/distorted tones, i am now using a
15watt fender superchamp xd into a celestion 1x12 which i put in the mesa combo cab.
the fender gives a great clean tone...which i wish i could get from the mesa.

thanks again.

 

[donnievaz]

That being said, the fixed bias platform isn't for everyone. So, more technical people modify the amp to allow adjustments to the bias. This comes with some risks (i.e. blowing tubes and what not) but if you know what you are doing, you can possibly get a better sound out of the amp.

In this case, MUCH better tone. The difference is not subtle at all.