New Studio 22+ Owner

[TiPiMods]

Just got a wonderful, clean 1991 Mesa Studio 22+ with EQ and reverb. The last owner stated he didn't play it for some years, so the pots made a lot of noise and had some dead spots. After cleaning with Deoxit F5 they work flawless again. Had also some issues with the send and return jacks, sometimes the sound dissapeared or becomes very low and crackling, then suddenly comes back to full volume. Had to clean the jacks and to plug in and out a few times to make the contacts work when nothing is plugged in.
It had original Mesa preamp tubes and some no name USA 6BQ5.

Next thing I did was measuring the output tubes current and found it much too high, they where dissipating nearly 14W. Found some nice NOS Brimar EL84 I bought some time ago for my Fender BJ but never used them. They idled at just 70% and sounded also a lot better.

Man, this little boy got some nice lead sound, creamy and lots of gain, easy feedback, really fluid...
as I always do, I tried different tubes and found out, that with 5751 in V1 and V2 the balance between clean and lead is much better than with 12AX7. The rhythm channel stays clean a bit longer (with a Strat till about 7 on the volume, with my Robben Ford Esprit till about 4) On the lead the gain is reduced but quite enough for my purpose, maybe I switch back a 12AX7 in V1, but right now I love it. Articulate, even with lots of gain, and this nice dynamic reaction on the picking attack. I heard someone once describe it like the sound it makes stepping on a plum :wink:

Also very interesting: tried the 22+ with my EV12 Thiele. Sounds flat, dull and lifeless compared with it's stock Black Shadow. Plus the stock speaker is a lot louder!

the only minus on this amp is the hiss and the hum. I cannot imagine to use the cleans of this little beast in the studio. My MKII is dead silent in comparison, also the BJ. Its quite the same hiss on clean and on lead. No other amp I know does that.
Someone knows a cure?

But anyway it's a great low watt amp with some amazing sounds.




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[tonejam]

Congratulations, that's one clean looking Studio 22+!
I use a 12AY7 in mine to even up the channel volumes, and it works great.
Yeah, they are too noisy for studio work, makes their name ironic. But what a great sound! I bought mine in 1990, after reading a review in Guitar Player magazine, which described them as "the best lead sound available". I bought an Express 5:25 about a year ago, but sold it recently. It just didn't sing like the 22.
cheers, Bill.

 

[TiPiMods]

hi Bill
did you change both V1 and V2 to 12AY7?
cheers

 

[RR]

hi Bill
did you change both V1 and V2 to 12AY7?
cheers

I can't recall but I changed 12AX7s with 5751 and 12AY7 but I don't recall which sockets (V1, V2) so it gave me a good balance between the lead and rhythm channel for my use. You do lose a lot of the preamp gain but I wanted my Studio .22+ to be have like a Mark IIB with EL84s!

If I needed a lot preamp gain, I'd get something like the Mini-Recto to specialize in this department.

As for the hum ... gosh, when I got mine, it hum and crackled. Since it was on warranty I sent it back. They claimed there was a run of Studio .22s that had flaw. It was corrected and was much quieter.

I tried it with a few speakers and find the Celestions (G12-H30[?]), Tone Tubby 40/40 as well as the stock speaker Black Shadow worked best with my Studio .22+.

 

[tonejam]

Just the V1 (if that's the one that most affects the overdrive, I get confused with this and the Express amp, I think it's a matter of changing V2 with it. Anyway, I'm 95% sure V1 is the one). You do lose some overdrive, but there's still plenty.
Also keep in mind the levels even up as you turn the master up. I have a mod in mine from London Sound that lets you turn the master volume up without getting too loud. This and the 12AY7 make the amp much more manageable.
I do agree with RR's comment. The .22 is noisy, but not necessarily THAT noisy. It might be worthwhile getting yours checked out.

The stock speaker was great, but I now have a 30 watt Weber alnico Blue Dog in mine which is creamy!
anyway, enjoy!
Bill.

 

[TiPiMods]

As I understand the schematic, V2 is the first tube the clean signal hits, when switched to overdrive the signal goes to V1 first and than overdrives V2a and the rest of the tubes. Quite unique, and different from the Mk series.
So if V1 has less gain V2 does get a lower signal and therefore doesnt overdrive that much. on the other side V2 is the tube which gets overdriven and therefor is more involved in the sound of the distortion.
I changed both tubes for a 5751 so the clean channel also stays clean a bit longer. If you want an overdriven rhythm sound and a not too saturated lead it's probably better to have V2 a 12AX7 and V1 some lower gain tube. I will experiment with that.

What I did to reduce some hum is: I put a shielded cable from the input to the board and the one which comes from the middle lug of the volume pot and goes to the board. I also found out that the chassis had no contact to the shielding foil on top of the enclosure, so I took some steel whool and cleaned the foil from the paint. That did reduce a lot of the hum.

I suppose the hiss is some inherent problem of the design of this amps, so I think I have to live with that.

 

[Bob Anthony]

Congrats! The S22+ is a temperamental little beast, but is a fine amp. I highly recommend getting the gain mod done that many have done to balance the two channels. I switched out the VS-12 with the Mesa MC-90 to make the sound less harsh, but stuck the original in a cab and run the two together, occasionally adding a rotating speaker. This makes for a much richer sound. On another note, Which issue of Guitar Player has the review of the Studio? I have a mountain of issues, many of which are going to be up for sale, and would like to find the issue or read the review.

 

[stokes]

An amp that age needs the filter caps changed.An amp that has sat unused for that long needs new filters even worse.When caps sit for long periods the electrolyte dries up from not having any current pass thru them.Causes hum at best,can explode at worst.Exploding filter caps cause a mess,I cleaned one up once and you cannot pay me enough to do it again.Worse than that,shorting caps can take other things with them,like transformer.Have the caps changed,use good quality caps,not the asian Xicons or whatnot.I like Sprague and F&T's.It will get rid of the hum and keep your amp from a catostrophic failure.

 

[tonejam]

It was actually a review of the Studio preamp, Bob. Guitar Player Magazine, April 1989.
This from reviewer David Hicks.....

"As usual though, I do have a beef! While the overdrive is as smooth and deadly as I expected, it doesn't have the amazing harmonic structure of the .22. This isn't too surprising, though; no one else's amp has it, either. I have a high opinion of all MESA/Boogie's products, but if you haven't heard a .22 in overdrive, it's my theory that you haven't heard the very best lead voice available."

not a bad rap for MESA's budget model, hey? I bought my 22+ in 1990.

 

[TiPiMods]

I highly recommend getting the gain mod done that many have done to balance the two channels.

What does the gain mod? does it lower the gain?
Because with the original 12AX7 tubes its like: clean/full shred.
With 5751 in both V1 and V2 its more balanced but the difference in gain is also huge.

An amp that age needs the filter caps changed.

I know that's a critical point with amps of that age and maybe not played for some time. On the other side I have a BF Deluxe from 63 with all original ( the nice brown paper) caps, which sounds fantastic and works flawless. I wouldn't go on tour with it, but I use this amp quite regular for club gigs in town.
But thats quality from the 60ties. A lot more of my Amps from the 80ties needed a recap.

I have to put out the board ( I hate that) to look if the R131 change was made and the other mods recomended for the footswitch circuit.

 

[stokes]

The gain mod involves replacing R292,a 470k resistor,with a 500k pot so you can vary the output from V1 when in lead mode.Pretty easy,effective mod.You have to cut the trace on the PCB between C5 and LDR2,one leg of the pot is connected to C5,other outer leg to LDR2 and the wiper to ground.
As for your BF Deluxe,if you like the way it sounds,thats up to you,but you are playing a "time bomb" with caps that old.If you change them it will definately change the way the amp sounds,which you may or may not like,but everybody I've done cap jobs for have been very pleased with the improvement in tone and response.I agree the caps they used in the early days were 100% better,but they werent made to last 50 yrs,and your amp does not "work flawless" as you think,it may work to your liking,but those old caps are putting a lot of strain on your amp.But back to the .22,what you describe with the effects loop jacks is quite common in amps with that circuit,keep in mind that the jacks may have to be changed eventually.If your pots still have any scratchiness,check for leaky cap feeding that pot.If you want it to be quiet,and they can be dead quiet,change the filter caps.There is also a lot of noise in these high gain amps from the tube in V1.All preamp tubes have a certain degree of microphonics,if a tube is noisy in the V1 position doesnt mean it is bad,its just not usable in that position,I have at least a dozen old stock preamp tubes that cant be used in V1 of my MKIIC+ but work fine in my lower gain Fender type amps.It takes some trial and error and trying different tubes.Like I said earlier,all preamp tubes have some degree of microphonics,age causes it to become worse and it shows itself sooner in a high gain circuit.

 

[igfraso]

I sent my Studio .22+ to Mike Bendinelli for him to add a fourth volume pot at the back of the chassis.
With this "Lead Drive" pot, you can dial the gain of the clean and the lead channels independently (it resembles more of a Mark II and III).

It is a very common mod in these amps. You can call it "Gain mod" if you want but it is actually a "Lead Drive Pot mod". It doesn't affect the gain available, it just adds a pot so you can dial in the amount of gain you want.

 

[TiPiMods]

thanks a lot for sharing your knowledge and a lot of useful information.

@stokes: from a technical standpoint you are right for sure, but I love the sound of the Deluxe a lot, its not so "boomy" and bass heavy like a lot newer Fenders, very organic and more midrangy. A tech once inspected it and said, if the caps look that good, no bubbles, foam or anything like that I can leave them alone, plus, what you said too, the sound will definitly change with new caps. I could also change all the plate resistors as this old carbon resistors produce a lot of hiss, but I want to leave this beautiful piece of history as original as possible. My main live amps are a Boogie MkIIB and a modded Fender BJ, and for the real loud Rock stuff one of my Marshalls.

One other question to the "tech" guys here: do you know, why the 22 has quite the same amount of hiss in the clean and the lead channel? this is very specific, no other amp I know behaves like that.

 

[stokes]

ery hard to diagnose via an internet forum based on a descriotion of "hiss".But noises are troubleshot by finding where they are introduced into the circuit.As you describe the noise as being identical in the clean and lead modes it is undoubtedly something associated with both channels.Since V1 is only in play with the lead mode,you can probably count that out.V2 is utilized in both modes,pull that tube and see if the noise stops.If so,it is something associated with that part of the circuit.Heres where it becomes difficult to pin down from where I sit,you call it hiss,but is it actually hiss,buzz,hum,static.Could be anything from a dirty/loose tube socket to a bad plate resistor and many things in between.If I had that amp in my shop,I would probably strongly suggest new filters,knowing the history of them,before trying to get ti the bottom of any other problem.It may sound to you like I'm trying to make $$$,but that is not the case at all.Bad filters cause all kinds of problems,not just the "classic" symptoms.Many times that alone cures what may seem to be another problem.In regards to the tech that told you your caps are okay because they arent bubbling or showing any signs.I wouldnt put much faith in that.Caps have a definitive life span,just like tubes.Manufacturers,even in the '50's and '60's say they have a shelf life of only 10 years,they arent meant to be used in a circuit for 50+ years.I understand that people want to keep things stock for vintage appeal,but not in an amp you want to play.Look,its your amp,you will do what you like,but if that BF Deluxe came to me evn for something simple,I wouldnt even turn it on with those old caps in there.In all the years I've been working on amps,I've only had to turn away one customer who didnt want to change the caps in a vintage amp,and he was back a year later for a new PT and all associated components.And I have never had anybody less than elated with the improvement afterwards.I gave a guarantee,on this board,a couple years ago,that if your caps are more than 10 yrs old,I would change them and if you didnt notice an improvement,I'd put the old ones back and thered be no charge.I had a few from this board take me up on it,as well as others from various contacts and nobody ever wanted the old ones put back.Caps are the heart and soul of your amp and need to be replaced from time to time,even the manufacturers will tell you that.

 

[TiPiMods]

Tweaked and experimented some more today and found some nice solutions: I put back a 12AX7 in V2 so the clean channel is a little fatter again. Especially with a Strat and the Volume at about 6 it's a real meaty, hairy sound on the edge of breakup. V1 stayed a 5751 so the lead sound has a bit less gain. (I am thinking about a lead gain poti on the back as some of you suggested, let's see)

I also shielded the conection between the middle lug of the master volume and the board, which was a nearly 25cm long single unshielded cable. Helped a lot, no increase of hum now, when you turn up the master.

The hiss comes definitly from V2, if I pull this tube the amp is nearly quiet. tried different tubes, but even with brandnew ones there's not much of a difference. No problems with microphonics though.

regarding the footswitch issue some users tell: seems that my .22+ is factory updated with the right R131 (1k/2W) and also the cap on the picture with the MB signature beside looks like a factory update.

 

[TiPiMods]

BTW: was the hardwood cabinet also an option for the 22+? I never saw one.
But I saw older Studio 22 out there with a hardwood cab.
thanks

 

[TiPiMods]

short update:
I played the 22+ on some gigs the last few weeks and have to say it's a really great sounding amp. Easy to carry, easy to dial in a great sound both on rhythm ans lead
And one more nice thing: the Studio Slip cover from Susan Bendinelli, originaly made for my Mk II, fits perfect on the Studio 22+

 

[nogalian]

An amp that age needs the filter caps changed.An amp that has sat unused for that long needs new filters even worse.When caps sit for long periods the electrolyte dries up from not having any current pass thru them.Causes hum at best,can explode at worst.Exploding filter caps cause a mess,I cleaned one up once and you cannot pay me enough to do it again.Worse than that,shorting caps can take other things with them,like transformer.Have the caps changed,use good quality caps,not the asian Xicons or whatnot.I like Sprague and F&T's.It will get rid of the hum and keep your amp from a catostrophic failure.

I bought a MkIIC from the GC once (on line sales) and when it arrived I took the chassis out to see it looked like the amp had been used in KFC's fryer area!! What a mess. Couldn't figure out where in the world this amp had been used! So I am guessing, based on your post, the caps exploded in this dude at some point?? Is that what it looks like? I did not know they would explode! I guess I better play my older amps more!! Use it or loose it

 

[TiPiMods]

yes, play em loud :twisted:
every two weeks I fire up all the amps in my studio to keep them in shape. plus it is fun to plug in and listen to all their great voices.
I must say: in nearly 40 years of playing and tinkering around, modding, repairing tube amps, old tube radios etc I never ever saw one with exploded caps. (I mean, I dont do that for living, I am musician, not a technician, tube amps are more like a hobby)
What I know is: caps explode when the polarity is wrong, (we did that when we where teens for fun...)

merry X-mas

 

[nogalian]

I guess I better play my older amps more!! Use it or loose it

yes, play em loud :twisted:
every two weeks I fire up all the amps in my studio to keep them in shape. plus it is fun to plug in and listen to all their great voices.

:lol: :lol: Right ON TiPiMods!! Best RX I have recieved in a long time!! :lol: :lol:
My Wife is gonna LOVE this advice!!! :shock: