Soundwise these are gems. Sound fairly similar to mark amps of that era, but dont need to be loud to sound good. Great practice amp for your livingroom.
This monster was manufactured when there were more brands of decent quality and decent priced EL84 valves available. You did a great job in your repairs to tame the beast.
The Inspector Gadget theme was worth the price of admission alone. As I understand it, those things were used a lot for lead work in studios (rather than general workhorse).
I have owned Studio .22 and .22 +. I have modded the .22 to have the Lead Master and Lead Gain, etc. I changed some fixed resistors to control the gain and volume for the gain channel vs cutting traces and putting in pots. I found that a speaker change was a must. I had great success with the Eminence Wizard in this amp. Great vid series, Brad!!
Always interesting to see your work, Sir. I've got the "boogie" badged .22 (not the +) that's had a few tweaks and it sounds pretty decent. It's long overdue having its nappy changed though so I might give that a shot, having seen these videos.
I had one of these for my first "good" tube amp. I liked it at the time, although it really was more suited to higher gain than I desired. A decent drive sound, a very good clean sound as I recall, overall a bit boxy. Ate tubes every 6 months like clockwork, and that's when USA Sylvanias were available from Mesa at a reasonable price.
I'd say all of that about this unit. I do maintain several amps that run over 400v on the plates of EL84's and they seem to be stable over the long term providing the plate and in particular, the screen dissipation is kept in check.
a MOSFET /zener B+dropper might help here...I have several Peavey Bravos, and they feed their el84s 420V ;) In the end you got the little Messa sounding pretty good!
MOSFET would be the better option, but mounting it in this amp would present several challenges. I really shouldn't need to redesign every Mesa that comes in, but here we are, I guess. LOL!
The Zener diode is an easy way to reduce B+ it’s just a matter of getting the right zener (voltage and power ratings). Brad, why do you like a MOSFET, I opt for a circuit with minimal components where I can. Less to go wrong.
@@TheBoomtown4I used to love his channel, then it somehow went in strange places. When his wife left and everything was everyone else’s fault, I had to bounce. I went back recently to see if he’d gotten better, but sadly not. A nutter indeed.
Just to let people know - RX BrownBox's are now available in Australia for 240V at DeluxeGuitars, they are called a "BROWNBOX 200". I personally own one, they work great and are built like a tank. I often see voltages up to 247V where I live. I run my amp at 230V through the BrownBox, and you can hear a tonal improvement from running on direct mains. The BrownBox isn't cheap, but will last you a lifetime, and it will end up paying for itself in valve saving.
Another great video, Brad. Could you not reduce the B+ using the "power Zener" (i.e. MOSFET + Zener) method? That approach should leave the heater voltage alone.
Super trilogy - and three parts isn't too many for me! :) (Then again, I'm not one of the cool kids.) My son's pal has a DC-3 that eats tubes and not so long ago almost went up in flames. Poor guy has had it "repaired" multiple times ... if only he could get a fix as good as this one!
Sounds like it may be too far gone for repair if it went up in flames. Believe me, mate, I am very sorry to hear that and I wish I could help out. Let me know where you are via www.bradsguitargarage.com.au/form/contact-us/ And I'll check if there's someone nearby we can trust.
Why not power scaling for the plates and screens? Split the B+, power section side hits the variable mofset, preamp side flies past it. VHT does this in a hamfisted way to get "bedroom" volumes, way simpler than the London way tho.
those pots are the worst... usually the clip inside the pot snap right off. I resurrected on by dissecting the pot in front of him and found it was glued together before that
load the power supply with a resistor in series after the first cap . Even a small resistor before the first cap and a small cap before that resistor. My thoughts.
@@BradsGuitarGarage You just answered the question I was about to ask (whether a high wattage chassis mounted power resistor would have been a suitable option).
Could you drop the plate voltage by adding a dropping resistor between the B+ and the center tap of the output transformer. I have never tried it but was wondering if it is even possible.
Wasn't that a rebadged Princeton with the guts swapped out? It was def Carlos saying this little amp can really boogie! By def...l mean guitar mag folklore!
That would dissipate a lot of power. A MOSFET would be a better option, but mounting it would be another challenge that this amp design doesn't lend itself to.
Soundwise these are gems. Sound fairly similar to mark amps of that era, but dont need to be loud to sound good. Great practice amp for your livingroom.
I can understand the struggle working on Mesa amps, but they sound really good. Great job sir per usual!
This monster was manufactured when there were more brands of decent quality and decent priced EL84 valves available. You did a great job in your repairs to tame the beast.
The Inspector Gadget theme was worth the price of admission alone. As I understand it, those things were used a lot for lead work in studios (rather than general workhorse).
Mesa/Boogie never ceases to confuse me.
I have owned Studio .22 and .22 +. I have modded the .22 to have the Lead Master and Lead Gain, etc. I changed some fixed resistors to control the gain and volume for the gain channel vs cutting traces and putting in pots. I found that a speaker change was a must. I had great success with the Eminence Wizard in this amp. Great vid series, Brad!!
Good work, mate!
I'd love to do a deep dive on modding these things, but I just have nowhere near enough spare time to do so.
Against all the odds you made this thing sound great. Nice one!
thanks for the link for standoffs
13:40 really dialed in a nice tone here. Great vid and demo after.
Thanks Brad.
you make me realize how much i still don't know..... I love your way of dialing in an amp!
you got my sub!
Another Ill designed amplifier from “The Spirit in Art in Technology”…way to go Mesa..!
Great work you are an outstanding craftsmen
Add a small transformer 240 to 50volt to take down the voltage by 50 volt or whatever you find suitable..
Always interesting to see your work, Sir.
I've got the "boogie" badged .22 (not the +) that's had a few tweaks and it sounds pretty decent. It's long overdue having its nappy changed though so I might give that a shot, having seen these videos.
High quality content,
Niche, but well made. A+
I had one of these for my first "good" tube amp. I liked it at the time, although it really was more suited to higher gain than I desired. A decent drive sound, a very good clean sound as I recall, overall a bit boxy. Ate tubes every 6 months like clockwork, and that's when USA Sylvanias were available from Mesa at a reasonable price.
I'd say all of that about this unit.
I do maintain several amps that run over 400v on the plates of EL84's and they seem to be stable over the long term providing the plate and in particular, the screen dissipation is kept in check.
a MOSFET /zener B+dropper might help here...I have several Peavey Bravos, and they feed their el84s 420V ;) In the end you got the little Messa sounding pretty good!
MOSFET would be the better option, but mounting it in this amp would present several challenges. I really shouldn't need to redesign every Mesa that comes in, but here we are, I guess. LOL!
@@BradsGuitarGarage with great brains comes great responsibility..if you let it ;)
The Zener diode is an easy way to reduce B+ it’s just a matter of getting the right zener (voltage and power ratings).
Brad, why do you like a MOSFET, I opt for a circuit with minimal components where I can. Less to go wrong.
Thanks Brad, interesting videos. I remember Guitologist had an EL-84 Mesa on his channel, a DC-3. He had trouble with the bias circuit iirc.
So then the guitologist has mesa biasing, legal and mental problems. Guy’s a nutter.
@@TheBoomtown4I used to love his channel, then it somehow went in strange places. When his wife left and everything was everyone else’s fault, I had to bounce.
I went back recently to see if he’d gotten better, but sadly not. A nutter indeed.
Just to let people know - RX BrownBox's are now available in Australia for 240V at DeluxeGuitars, they are called a "BROWNBOX 200". I personally own one, they work great and are built like a tank. I often see voltages up to 247V where I live. I run my amp at 230V through the BrownBox, and you can hear a tonal improvement from running on direct mains. The BrownBox isn't cheap, but will last you a lifetime, and it will end up paying for itself in valve saving.
Good to hear, mate! Thanks for letting us know, I'll look into it.
Another great video, Brad. Could you not reduce the B+ using the "power Zener" (i.e. MOSFET + Zener) method? That approach should leave the heater voltage alone.
I don’t know why Brad didn’t use the zener diode to reduce voltage. Very easy and effective.
Farking good video once again chief. Thank You
Seems like you rebiased a win. Increased the voltages barely 5% and got a 30-40% drops in idle dissipation. Straight to the pool room there mate!
Super trilogy - and three parts isn't too many for me! :) (Then again, I'm not one of the cool kids.) My son's pal has a DC-3 that eats tubes and not so long ago almost went up in flames. Poor guy has had it "repaired" multiple times ... if only he could get a fix as good as this one!
Sounds like it may be too far gone for repair if it went up in flames.
Believe me, mate, I am very sorry to hear that and I wish I could help out.
Let me know where you are via www.bradsguitargarage.com.au/form/contact-us/
And I'll check if there's someone nearby we can trust.
I had a bias pot on a 1964 Twin Reverb with the same problem, was a pain to figure why the bias keep jumping around.
Why not power scaling for the plates and screens? Split the B+, power section side hits the variable mofset, preamp side flies past it. VHT does this in a hamfisted way to get "bedroom" volumes, way simpler than the London way tho.
Thanks, dude!
Everyone else has been too polite, but I really think that Brad should be called on the outrageous visual pun in the thumbnail 😉
those pots are the worst... usually the clip inside the pot snap right off. I resurrected on by dissecting the pot in front of him and found it was glued together before that
load the power supply with a resistor in series after the first cap . Even a small resistor before the first cap and a small cap before that resistor. My thoughts.
That would need to be a chassis mounted power resistor, I think we'll be fine in the case.
@@BradsGuitarGarage You just answered the question I was about to ask (whether a high wattage chassis mounted power resistor would have been a suitable option).
zeners are your best friend dropping b+
Love the little “Hall of the mountain king” riff for the true champions.
Is the Standby switch circuit as poorly designed as everything else, perhaps overvoltaging the filter caps or causing the switch to fail prematurely?
Could you drop the plate voltage by adding a dropping resistor between the B+ and the center tap of the output transformer. I have never tried it but was wondering if it is even possible.
El84 is the battered housewife of valves...
So far from the original "Boogie" that Santana had it's a crime.
Wasn't that a rebadged Princeton with the guts swapped out?
It was def Carlos saying this little amp can really boogie!
By def...l mean guitar mag folklore!
You must have a good backlog if your bias notes were done on June 11th. (lol, dumb joke) Thx for the great work.
would a voltage regulator on screen supply a good solution to prevent destruction on el84s? let say bringing down voltage to 250 volts...
That can work, but the easier way to do it is with Zeners on the screen supply. This will affect plate dissipation also.
@@BradsGuitarGarage Cheers Brad 👍🏻
I seem to recall somewhere Kurt Cobain used these in his live rig feeding a power amp. Can anyone recall?
First "mod" I would do is blutak on the 750hz slider so it can't go above halfway😂
HAHA! Yes. Lock and tag that bugger out!
How many hours did you have into that repair, or should I say days?
Nothing too dramatic, coupla hours.
Any thoughts of trying a high wattage sag resistor to drop the B+, to run the tubes at lower B+.
Just saw someone else floated the idea already.
That could work, but would totally change the response of the amp, I think we'll get away with it on this one from past experience.
@@BradsGuitarGarage, maybe a heavt duty zener diode to drop the voltage a bit?
That would dissipate a lot of power. A MOSFET would be a better option, but mounting it would be another challenge that this amp design doesn't lend itself to.
Well we found out what Mesas are good for: Grieg’s Peer Gynt. 😄
"sprayin the loob around like a drunkin sailor "
A Mexican standoff calls for a Mexican beer and a plate of nachos.
That amp is worth the repair only because Kurt Cobain used it hehee grreat job
That thing should be taken out of circulation permanently
Nah, she's sweet now, mate!
Nice job Brad.
Don’t get ‘the shits’ about 3 videos, it’s been an informative series, and a good laugh as usual.
@@TheMorganOrganyeah, they were all interesting. Was happy to see the new vids pop up. Didn’t bother me at all.
You're far too kind about that thing. It's got virtually no redeeming features except its aesthetic.
I hate Mesa amps. In the 80s I tried the triple rec. They suck
there was no triple rec in the 80s ..... just sayin' 😂
I looked back in our videos. Your right the mesas showed up in the 95 videos. Thanks for pointing out my mistake.@@pacocasanovas1605