*HELP* Complex rig. Mesa 400 Non Plus. JJKT88's. Lots of Pedals.

[godspeed68]

Hey guys.

I'm completely lost on this one.

First I'll describe everything, then I'll post my chain.

Here goes:

I've been using a 1986 Mesa 400 (non plus) for 3...almost 4 years now. It's been retubed with the classic JJ Electronic KT88/ECC83s combo.

Generally once a year, I "blow" a power tube. By this, I mean there is tube failure, resulting in damage to other electrical components of the amp (ie: filament resistors, screen grid resistors etc etc). I've seen a blue flash shoot out of the amp in the past during tube failure, I've melted solder joints in the amp just due to heat...

So once a year I get new tubes, have some work done on it, and I'm good for another year...not as long as I'd like my tubes to last, but I've become used to it at least...


until...

I blow out my amp in Boston and take it to a *to remain nameless* tech on the east coast.

A new KT88 is put in, a bias mod is installed, and I'm sent on my way.

Fast forward to last month.

I start hearing static during the attack of my notes. Turns out, you can even tap on the chassis and hear it.

I take it in to the local shop, and after tapping all over the inside of the amp, the shop guys say it's either a tube problem, or a circuitboard problem.

So I send it to a local amp tech. Really reputable guy. He finds some weird **** inside of the amp - a 220ohm resistor where a 2.2k resistor should be...so he did some stuff to it and sent it back.

It worked well but sounded different...for two gigs.

I blew it out again - this time there was no burning electrical smell. Tech says it was a blown ECC83S pre tube. He puts some "old military grade RCA's" in it.

During our next rehearsal, I notice my Lehle D.loop switcher's "Buffer" fails. It cuts my signal out completely. I also notice that I hate the sound of the tubes. I also notice that my tone because EXTREMELY compressed, and just about disappeared at times while playing.

It was when I moved my Fulltone Bassdrive pedal into the front end of my amp that I blew a KT88...literally within 30 seconds.

My tech talks to Mesa, and gets some upgraded parts that will lower the B+ voltage in the amp some...(not sure how that affects the the amp) And I talk to Eurotubes for quite sometime before eventually ordering another re-tube.

My tech installs the tubes and finds that even with the bias mod, he can't get the tubes to bias where he wants them...removes the cheap bias circuit and installs a resistor to test the amount of current going to the tubes.

Also informs me that the KT88's are MICROPHONIC!!!

I take the amp to see for myself...

You can hear a tap through the speakers when you tap the tubes.


so here is where i am at and what i am asking...

I need someone to comment on the build quality of the JJ KT88's.

What problems should I expect when using KT88's in a Mesa 400 (non plus) at consistent loud volumes?

Is my amp not able to handle the signal chain that I'm using?

Is my signal chain "in-correct'?

Is there a better tube to use that is not NOS and completely out of my price range?


overall is there something I should be doing differently???

Am I doing something wrong with my signal?

--------------------

FRONT END BOARD



EFFECTS LOOP BOARD


Signal Chain

>'s designate direction of path, ()'s will describe the settings of the respective pedals, and [ ]'s and { }'s designate parallel loops.


FRONT END BOARD (powered by Voodoo Labs Pedal Power 2 Plus):
Stock passive Fender '62 RI Jazz (Full volume) > MOOG Analog Delay (drive and output controls at 2:00) [EHX Bass Microsynth] > Lehle "Little Lehle" True Bypass Looper/Bypass Switcher [BOSS RC-20 Loopstation (Input Gain and Playback Output levels at 12:00)] > MOOG Lowpass Filter with expression pedal (Drive at 1:30 - The drive setting is active even when the pedal's effect is bypassed) > Damage Control TimeLine Delay (No gain controls, even mix) > INPUT 2 OF 1986 MESA 400 NON-PLUS HEAD.


EFFECTS LOOP BOARD (also powered by a second Voodoo Labs PP2+):
Mesa Effects Loop Send > Fulltone Bassdrive (Older model. Made in '03/'04 I believe. Middle switch is in the "F" position - it's the loudest and most full sounding. Volume is at 10:30, Tone is at 2:30, Overdrive is at 2:30, Boost is at 9:00) > Lehle "D.Loop SGoS" (Two way True Bypass Looper/Bypass Switcher with adjustable Buffer Volume set to 10:00) [Loop A Send- EHX Micro POG (Dry at 1:00, Sub Octave at 11:00, Octave Up at 1:00) > Maxon AD-999 Delay > Loop A Return] [Loop B Send - Radial "Big Shot" A/B/Y {A - Dry Signal} > Side A Return of BOSS LS-2 Line Selector {B - Heavy Electronics "Radio Havana" Lo-Fi (Older model, Gain and Level set to 3:00) > BOSS RC-50 Loopstation (Instrument Input and Master Volume set to 12:00)} > Side B Return of BOSS LS-2 Line Selector - BOSS LS-2 Output (with A and B Levels set to 12:00) > Loop B Return] > Mesa Effects Loop Return (Effects Blend set to 7:00)


Mesa is fed into a Bergantino NV610.


Mesa EQ settings - Middle @ 7, Bass @ 4.5, Treble @ 4, Master @ 7-8 but no higher than 8 (seems to be no mans land above 8), Volume 2 @ 4, Volume 1 @ 0. Active EQ settings have no db markers, but there is a slight boost at 40, 625, 1560 and 3900. 100 and 250 are just about level, if not cut slightly.

--------------------





To anybody who helps me address this problem - Thank. You. Very. Very. Much.

[godspeed68]

It is notable that my front end board boosts the signal hitting the preamp substantially due to the drive controls on the Moog Lowpass Filter.

Also - all of my overdrive/distortion happens in the effects loop as to drive the power tubes...

[godspeed68]

bump the craziness.

[morganmcd]

distortion in the effects loop?

[Destructobot]

Nothing you can do with the pedals will make the amp go all haywire like that. Slamming the front end just makes the preamp tubes clip.

Sounds like you need a new tech. I've been through that crap before, until I found a top quality amp tech. There's no excuse for that crap - those techs you used should offer to fix it for free when you get problems that quickly after they've worked on it.

[BassmanPaul]

To clear up a question, when you installed the '88s the amp was biased to suit them? And every time you replaced a tube set or did you just replace the blown tube????

[agreatheight]

Originally Posted by Destructobot

Nothing you can do with the pedals will make the amp go all haywire like that. Slamming the front end just makes the preamp tubes clip.

I am not a professional tech, but this is my feeling as well.

[James Judson]

Welcome to the world of tube amps. As an electronic engineer I'm amazed tube amps last as long between service as they do. The elements inside a tube are very delicate and couple that with a 80lb chassis. Then move that thing a couple times a week. Can't count how many times I had to tell well meaning girls to "please put that down, I don't need any help".

I recommend finding a really good tech (they are few and far between) and carry a complete set of tubes.

As a bass player for 40 years plus I can't imagine the need for all those pedals. If you can not get a decent sound just plugging straight into your amp then you need to 1. change your axe or 2. change your amp or 3 learn to play. I know what your response is "my tone" or "my genre" or "your to old to understand". I get compliment from other bass players that my tone is awesome and they don't realize half my "tone" is that kick drum.

Just my $.02 and YMMV

[Mr. Foxen]

Amp probably needs a full overhaul rather than patching the most obvious problem. Might besomething that isn't directly related to the failing components. Take it to someone actually interested in fixing amps, rather than making it work and taking your money.

[BassmanPaul]

A few comments on James' post if I may. While I agree that I do not understand the need for that many pedals it's not my rig, my sound nor my performance. If the OP feels that the pedals help him entertain his audience who am I to gainsay him. IMO the same applies to James. I have a few pedals which get used infrequently. When I do use them they can be a lot of fun. BTW I'm coming up on a half century of being a slave to my basses.

As I posted earlier tubes are much tougher than folks think. Moving a tube amp was a perfectly normal activity just a few decades ago. They don't have to go in for a 5000 mile check out/service. There are hundreds of tube amps out there still happily using the same tubes they started out with. Granted back then 100W was a big amp but still they got dropped, fell off stages, got banged around in the truck, the whole shebang of misfortunes and they still worked day after day, week after week and year after year.

Finding a good tech is a given unless one learns how to fix the things properly for themselves.

Carrying a set of tubes doesn't do you much good unless they are matched to the tubes already installed. Setting the bias correctly for a new set of tubes is vital for long life of the output stage. Replacing just one tube in a set is rather like the Goldilocks story, it could run too cold, too hot or, if you are very very lucky, be just right.

[godspeed68]

Originally Posted by morganmcd

distortion in the effects loop?

Yes. I know it's weird, but the Bass Drive directly drives the power section this way. Overdriven JJ KT88's sound amazing to me.

[godspeed68]

Originally Posted by Destructobot

Nothing you can do with the pedals will make the amp go all haywire like that. Slamming the front end just makes the preamp tubes clip.

Sounds like you need a new tech. I've been through that crap before, until I found a top quality amp tech. There's no excuse for that crap - those techs you used should offer to fix it for free when you get problems that quickly after they've worked on it.

It's amazing the amount of people that say the same thing, and I for the most part agree with it, unless there is some sort of malfunction with a pedal...

As far as the tech is concerned - He is quite literally one of the best in town. Maybe I'll have to take it elsewhere...

Also, his prices are very reasonable.

[godspeed68]

Originally Posted by BassmanPaul

To clear up a question, when you installed the '88s the amp was biased to suit them? And every time you replaced a tube set or did you just replace the blown tube????

When I blew my amp out in Boston, I took it to Fuchs in NJ. This guy does work for The Police and builds very high end amplifiers.

He replaced a single tube rated to match the rest of the KT88's that tested out "acceptable" to him. Also, he installed a bias mod. I did not see it myself, but I'm pretty sure he had a single trim pot control the entire bias circuit.

Normally, I have the entire sextet replaced with tubes that are rated to match a 400 non plus, sockets cleaned and tensioned...everything.

[Smallequestrian]

Originally Posted by James Judson

As a bass player for 40 years plus I can't imagine the need for all those pedals. If you can not get a decent sound just plugging straight into your amp then you need to 1. change your axe or 2. change your amp or 3 learn to play. I know what your response is "my tone" or "my genre" or "your to old to understand". I get compliment from other bass players that my tone is awesome and they don't realize half my "tone" is that kick drum.

Just my $.02 and YMMV

Thanks for your wonderful contribution. Remember, not everybody plays classic rock.

[godspeed68]

Originally Posted by James Judson

Welcome to the world of tube amps. As an electronic engineer I'm amazed tube amps last as long between service as they do. The elements inside a tube are very delicate and couple that with a 80lb chassis. Then move that thing a couple times a week. Can't count how many times I had to tell well meaning girls to "please put that down, I don't need any help".

I recommend finding a really good tech (they are few and far between) and carry a complete set of tubes.

As a bass player for 40 years plus I can't imagine the need for all those pedals. If you can not get a decent sound just plugging straight into your amp then you need to 1. change your axe or 2. change your amp or 3 learn to play. I know what your response is "my tone" or "my genre" or "your to old to understand". I get compliment from other bass players that my tone is awesome and they don't realize half my "tone" is that kick drum.

Just my $.02 and YMMV

I really appreciate your advice. It's important to remember the simplicity of your advice, as you can get lost in a lot of bull$**t and forget that you are a bass player.

How all of these pedals are set up and what they produce: Has nothing to do with my technical ability, but instead has everything to do with experimental sounds - taking things that are conventional and doing unconventional things with them.

I understand that because you are experienced, you can appreciate a bassist doing his thing.

[godspeed68]

Originally Posted by Mr. Foxen

Amp probably needs a full overhaul rather than patching the most obvious problem. Might besomething that isn't directly related to the failing components. Take it to someone actually interested in fixing amps, rather than making it work and taking your money.

What do you mean by "full overhaul"?

[iamdenialNJ]

Your rig ****ing slays man...never did like my mesa 400+. Sorry, I can't help but damn re-tubing every year!? Something sounds wrong....

[godspeed68]

Originally Posted by iamdenialNJ

Your rig ****ing slays man...never did like my mesa 400+. Sorry, I can't help but damn re-tubing every year!? Something sounds wrong....

Thanks man.

Yeah - I get some volume out of this thing. I have to keep up with the Green Matamp that my guitarist uses.

[BillJarrett]

Have you thought about contacting Rich at Mesa and discussing your problem, as well as possibly a referral to a Mesa tech locally?

[godspeed68]

Originally Posted by BillJarrett

Have you thought about contacting Rich at Mesa and discussing your problem, as well as possibly a referral to a Mesa tech locally?

I guess I left that conversation up to my tech and Mesa.

During the conversation they concluded that it was either a tube problem or something with my pedals.

Eurotubes insists that my tech doesn't know what he is doing.

My tech insists that there isn't a currently produced high quality KT88 on the market.

I don't know who to side with on this one.