Hi. I am Chris, The Guitar Amp Tech, working in Sydney, Australia. If you have a vintage valve amp, a modern valve, or solid-state amp, I will get it back to sounding its best for you.
I have some famous customers, but most are weekend warriors, like me, who are just as passionate about their sound. I also do repair work for major Sydney music stores.
There are a lot of myths in the amp world. I will do my best to address them as we cross them. Likewise, if you think I’m talking garbage, let me know.
I did my Electrical Engineering degree at the University of NSW. When I was 17, repairing my amp was my major goal in life. In some videos you can see that first bright green paneled Savage amplifier. It still doesn’t work!
Every 2 weeks I will be uploading videos of my more interesting repairs and offering some insights along the way. Some videos are short, some silly, and some detailed. It depends on time between repairs and the amp which inspires me to press “Record”.
Hi thanks for these informative and funny videos😂. Could you please make one on the subject of how safe is diming master volume on amps, with reactive loads or attenuators?
Fantastic!!! Thanks for getting so detailed in your explanations of things!! I have a 1965 Princeton NR that I need to do some checking on! I wish you lived in the USA so I could just bring my amp to you!!
I hope Fender sees these amazing vids and takes care AT LEAST of the resistors/capacitors! Either better design or metal resistors/capacitors to the chasis!
@@theguitaramptech Without the electronic / electricity, our mechanisms do not move. Sir you are sage! Keep on spreading the knowledge and wisdom. Peace out from Virginia Beach, Va!
Hi Chris, a bit late on your video, I want to remove the zeners on mine, but I’m not very educated on electronics, I do know how to solder and that’s about it, I repairs stuff watching tutorials like yours thank you very much!! I was wondering if I clip the zeners and leave the tips soldered, is that enough? Or should I I make an effort to unsolder them? I don’t know if leaving the tips is dangerous or if it will cause static noise on the signal, thanks for your help and keep the great work! Greetings from Mexico!!
Thanks for your email. I appreciate you watching and subscribing to the channel. Because the Zeners are paralled to the cathode resistor, it is fine to just clip them out.
Dreadful bloody power filter cap wiring under that piece of driftwood Chris! Too much glare on those o/p tube monitors; I could barely see them mate! Onto part 2 !---->
Thanks for your input, Neville. Yes, the amp looks like a high school project and not a premium-priced product. You are right about the glare, which I didn't notice until the editing stage. I have since replaced that overhead camera (with no monitor). I think the results are much better in the recent videos. It is SO EASY to spend money on this non-income-earning hobby of making videos, Neville!
@@theguitaramptech Yeah hobbies are expensive; no doubt! Despite whatever even minimal returns we get though, it's always money well spent due to the satisfaction we enjoy, making something work just a little bit better! Only constructive criticism being offered here Chris, & I'm glad you received it in the spirit it was intended! Hah! I was gonna say that unterminated mains wire there looks like one of those 'gimmick' capacitors I've seen used inside a couple of old valve radios. They 'peel off' a turn or three of the wire to get the right value. But it appears somebody has already mentioned it! D'oh!
How can other premium amp brands like Matchless, Deizel, Soldano, or Freidman make beautifully constructed amps to suit their boutique price-point, but Mesa makes such poor quality? All I can say in defence of Mesa, is that their marketing is sensational.
@@theguitaramptechonce I asked for and they sent me a sheath of promo material, with photos and text so luscious I wondered what they were smoking. In a pic of a bass amp it was clearly visible that the chassis lacked the grommet where the power cord entered the amp.
It'a hard to read, but its a "B". When you can't read a letter referenced this way, look at another similar amp schematic that is more legible. In this case the "B" connection goes to the 220K mixing resistor (near the Master Volume pot) as it does in other large Fender amps. Tanks for the question, John.
@@rcleon1431 The only USA hand-wired Deluxe I have worked on in Australia is the one you can see and hear in this video. Its made by Clark Amplification. Very well built.
The l is silent in solder. That's why we don't say it. 🤦 Just like when you say schedule. There's a "C" in there but you don't say it. Instead, you say "shed-jewel". Where's the "C"? It's SKED-JEWEL. There's a C in there. Just like when you say SCHOOL. You don't say shool. You don't skip the C like you do in Schedule. Makes zero sense. You observe the c in one words that starts with "SCH-" but you ignore it in another word that starts with the same 3 letters and is pronounced exactly the same. We can say solder without the L all we want. It is you all who have the messed up language 🤷 it's SKED-JEWEL. Just like School. You don't say shool. So why say shed-jewel? That doesn't make sense. At all. Where's the consistency? 🤷🤷🤦
I hope you are joking, as was I. If you didn't know already, I love the USA (except for the gun laws and healthcare ;) ) I'm heading to LA in January for NAMM. I've lost track, but between doing shows, holidays and NAMMs, it would be at least 35 trips. I may have even seen more of your beautiful country than you....Maybe. Out of interest, how many times have you been to Australia?
Kester makes liquid flux. Not sure if you know this. I have 2 different types. One is clear and is a no-clean flux. It leaves no residue behind. The 2nd is a brown liquid flux that's pretty sticky and leaves a lot of residue to clean when you're done. I won't solder without them. Even if I'm just soldering a ground wire to a pot, I drip some onto the back of the pot and solder away. It makes all the difference in the world. I actually just bought a new 2024 Hot Rod Deluxe IV for myself and it came in today. It sounds incredible! I just tested everything to be sure there were no issues. Then I put it up in the hall closet because it's for my bday in 6 weeks. 😁 For those plastic jacks, I intend on just leaving a cable plugged in all the time and never removing it. Hopefully that will put less stress on the joints so they don't break loose eventually
Just make sure you wrap you guitar lead around the handle twice before plugging it in, and always throw a towel over the control panel when you are not using it. I agree that HRD's sound excellent once they have been set up properly.
@@theguitaramptech awesome. I didn't even consider wrapping the handle. Thank you! One thing I have been wondering about. I should probably wait until it's out of warranty before I have reliability mods done like new jacks, the 5w resistors lifted off the board, new caps, etc... right? Or before doing them myself possibly. I don't gig and usually only play for 20-30 mins at a time, up to 6 or 10x a day sometimes lol. So it won't be cranked up much, only the rare times that everybody's gone, and not for hours at a time. With that, I'm hoping maybe I can get a little more use out of it before the usual issues come up. Or perhaps they won't come up at all before the warranty is up. Does that seem logical at all? Or am I dreaming?
Hi the be100 I was referring to is a pedal not a amp and what I was making as a point is that the tweed tone amp sounds good enough in its own right as evidenced in some of the videos but its a real struggle adding pedals. Interesting that the artist own videos all demo the amp without pedals.
So you prefer that the fuse be hot all the time, no matter what the switch position is? Seems like changing a fuse becomes a delicate operation. Maybe I am misunderstanding?
It is a very important and good question, Brian. What would you say to St Peter at the pearly gates when he shakes his head and asks, ‘Why would you have trusted your life to a cheap mechanical switch?” St Peter knows that if a short occurs downstream of the fuse (including the switch), the fuse disconnects the Active from entering any further into the amp. So by positioning the fuse before the switch, the entire circuit-including the switch…and YOU, are protected. Another precaution is to have the hot Active wire from the power cable connect to the REAR of the fuse holder. But you have made a valid point. I will make up a bunch of sticky labels to say: “To avoid death, remove power cable before changing fuse” Thank you Brian.
My teacher in 1976 had one of these Mk1s. I knew of them as a “boutique” amp built to do things a Fender could not do. These seem to be worthy of complete overhaul to at least benefit from quality components and workmanship. I agree that the graffiti is not worth a damn. I still swear by my Fender Princeton Reverb, but enjoy seeing this ghost of my distant past revitalized.
Thank you Brian. Yes, I too fell for the brilliant marketing of Mesa. Sadly, the reality does not live up to the hype. If one loves the sound of preamp fizz and crossover distortion, we can only put that down to matters of taste.
Pretty thorough job Chris! You tried to think of all the potential problems with this amp. It's called 'preventative maintenance'. Good stuff! They used lacing twine in Telecom years ago too. They taught us 'lacing stitch', not 'self-undoing stitch', as they called them back then. To keep everything laced in, they'd make us lace in other lengths of the waxed nylon twine along the run to lace up the 'branches'. We'd have to tie a 'constrictor knot' at the beginning of the lacing run, so it would not come undone, being sort of slippery from the wax. They never called it a constrictor knot back then, but my searching has actually confirmed the name. Just TRY to undo a tightly tied constrictor knot! - Ya gotta cut through it! I've managed somehow (?) to have a coupla big rolls of that very same lacing twine here at home! Ssshhh! Amazing stuff; you can't tear it off like electrical tape! - You'll deeply cut yourself! I've laced up a few looms on gear I've built, & even split the twine into thinner halves on the narrower looms, as it can flatten out to almost 3mm wide, which looks overdone. - Still you can't break it though! Ya gotta cut it or melt it! While we're not talking about cable ties, & after you heat tested your threaded nylon standoffs to 360° or whatever it was, I was a little puzzled as to why you didn't just use a nylon cable tie around that pair of 5W resistors, instead of contact glue? You'd just done the proof-of-concept experiment! As far as component leads 'clinched over' on the copper side of the board before soldering, I think it's a good idea. Regardless if it's a pita to replace the component. It gives extra mechanical stability to the joint, as well as more surface area of the component's lead actually soldered. When I built a pcb, I always 'clinch' component leads, except I.C's & sometimes TO-220 power devices. For neatness, I try to bend as close to parallel to the board as possible, & at 45°or 315° to the edge, whichever is most suitable to not have clinched leads shorting on each other. It looks quite neat too, & less kinda 'random'. I do this in preference to bending ' back down towards the track' as you do. - But I get where you're coming from though! I guess in that way I sacrifice a little bit of longevity for neatness! - Just a little though, cos I've never ever had a fault in anything I built or repaired as a result of a dry joint! Yep, those big old 'soldapullit' solder suckers definitely do a good job mate! I've just gotta remember to 'reload' mine over my solder 'ashtray' (a sardine tin with a felt base & a bunch of splashed [ashed] solder in it for weight), as it can spray out little flakes of solder about! Actually Jaycar sells a beige version, & new teflon tips too! - or they used to. I gotta agree with you on the solder braid too. Way too easy to overheat & lift tracks of the board with it. I find it useful sometimes when replacing SMD's (which you said you don't do), when I tin the pad then to get the pad nice & flat again for the new part. I've gotta cut the used part of the braid off very often though, as one false move not melting all the solder in contact with the braid & board will also rip fricken tracks off! Grrr! I'm old school as far as flux goes though. I use the honey type paste stuff. The pens never seem to apply enough for my liking. I'd rather apply too much & just exhale while generating all the smoke, then clean up with an I.P.A. soaked toothbrush/rag afterwards. The lid of my flux was nearly always fricken glued to the mofo jar, cos the flux goes so sticky, so I now just place an oversized plastic lid on top of the jar, & the adhesion of the flux shit securely holds the lid on till I break the seal to use the stuff! That's a nice looking ESR tester you've got there - with variable test frequencies & all! - Noice! I built the 'Silicon Chip' ESR meter in the cheap-ass jiffy box with the two 7 segment 1/2" led displays & a pushbutton. But it works a treat! It measures down to .01 ohms, but at only one frequency, at which I'm not sure. Did you clean the valve sockets? I never saw you do that. Have you seen those tiny little 'bottlebrush' type cleaners you can get for cleaning your teeth? They're called 'Pickers', or that's the brand. You can getem from Coles, & even more sizes from chemists. They're ideal for cleaning valve-pin sockets, with a dash of I.P.A on them. I love your idea of using dividers to set up & bend capacitor leads! I'm gonna steal that one! Actually I just bought a coupla metal nail files from Coles this arvo for cleaning contacts, as you suggested. At $2.50 each I bought two! - Gotta be one of the cheapest tools on my bench! Very handy to clean up my polystyrene military model parts too! Sorry bout the rant. I've gotta get a life! Actually I've gotta get a job! Too young to retire yet really.
I loved reading your comments, Neville. Please accept my apology for not responding to them all. From your experiences, I am thinking we must be of a similar age. I learned my lacing in the RAN. Yes, I (nearly) always clean tube sockets, but rarely show it in my videos as they are always too long. I used to use picksters but one boke off in a preamp tube socket and was a hell of a job to remove. Thanks for taking the time to write your message. Loved it.
@@elsaarmstrong-zp6ng yes, using DC for the heaters, especially in the preamp circuit, would definitely help with hum. On the other hand, it has also been a point of failure and adds to the complexity of the power supply.
@@theguitaramptechSimple transformer circuit with bridge rectifier and 6 volt regulator + capacitors zener diode etc ! No switch mode psu ! Linear psu would hopefully give a reliable DC supply for the valve heaters! Switch mode psu’s always noisy and unreliable in my opinion! Linear supply’s very little trouble! I have a old telephone xchange psu since the 60’s and still 48 volts DC at 10 Amps at the output! So why would DC heaters not work? Fraser
Im struggling with this amp. I find it best with a distortion pedal reverb and delay with the volume and tone at 10 0'clock Im using it in a soundproof music room playing at higher volumes and wearing music earplugs sounds great Has a great smooth growl But take the ear plugs out to hear it as the audience would.. not so good Its tone is too bright or kind of brassy not pleasing Im currently swapping the distortion pedals around to see what improvements I can get Currently I find a friedman be100 seems to work best as it has tone controls and a tight knob Now Im wondering if a better speaker might help. But once you get to speaker swap outs your really struggling Using a fender strat custom shop have tried les pauls richenbacher and custom tele with humbuckers. I find the strat works best because there are more pickup combinations
Hi Peter. Thank you for taking the time to comment on the TweedTone 12. When I was designing and prototyping it, it went back’n’forward to Artist many times for opinions I trust. Obviously, you have used the Bright Switch and the Presence (Tone) pot to take off the top end. I can only suggest that you must like a darker tone. A Strat on the bridge pickup can be a dangerous weapon! Can a speaker swap help? Sure, but do your research. Maybe a hemp cone. I must have missed the point of your comparison of this $450 12w amp to a 100w $7,000 Fiedman BE-100. Sorry.
The point I was making was that I found the amp fine without pedals but does not take pedals well except reverb and delay. The be100 I referenced is a stomp pedal not an amp. So unfortunately I think you missed my point
@@peterdempsey9153 thanks for clarifying that Peter. It’s great that we have different tastes. I designed it specifically to work with pedals or without.
Excellent videos! Fenders are very good, only concern I have is tubes/valves operating upside down! It must shorten their life and toast the caps and resistors etc above them! Any comments! Fraser!
You da Man, Chris. Thank you very much for sharing your wisdom. Keep those old electronics alive; do it right; do it with integrity; attention to detail; no shortcuts!
You have just made my day! Comments like yours inspire me and my colleagues (@PsionicAudio, @BradsGuitarGarage, @UncleDoug, @HeadfirstAmps, @TheGuitologist, and many more) to continue making videos. On the other hand, Trolls make me want to turn off my video cameras permanently. There's no money in making YT videos. Its just for the love of it, and getting to "meet" people like you. Thank you.
Hey Chris, great to see another one of your master tech videos..! Tips and expert info, just fab.. Nice bit of rocking out to Jimi..Take care..Ed..uk..😊
@@theguitaramptech Cheers Chris! Hah! I just checked, & the blue thumbs-up is there! I dunno mate. Before, it would just kinda highlight a faint white circle behind the icon whilst I was tapping it, which would extinguish when I removed my finger. The icon would remain white, as though it hadn't been tapped. So F.I.I.K. I think yanky tango are playing bloody games with my acct or sumthin. I was on a live chat the other day with Prof. Bart Kay & all my comments (& there were quite a few hehe!) got freakin deleted! I thought it was strange that no one was commenting on my comments in any way! Usually someone says something - but no, nuthin! Then I went back through the 'chat' again & it seemed EVERY comment that had a negative attitude towards the 'mainstream narrative' had been deleted! So the algorithm bots seemed to be working particularly assiduously on that occasion. But of course, my divergent or 'deviant' attitude from so much of mainstream narratives, coupled with my lack of hesitation in speaking 'my' truth, can get me into trouble sometimes. I've been 'punished' a few times by being banned from commenting for 24 hours, cos yeah, I've really hurt & bullied people you see, so I deserved to be hurt, bullied & punished as a consequence of my transgressions.
Good explanation Chris! I was thinking the dropping resistor would go in after the rectifier, & before the first filter capacitor. But you've installed it before the rectumfrier. Fair enough! I guess pre-rect is more suitable than after huh? Thinkin about it, before the rect would reduce the effective AC waveform reaching the rect., so it would have more of a valve-sag sound. Is that right?
Good job mate! Looks like you've done all the standard reliability improvements to keep this girl goin for years n years! I like the earthing improvements you've done; self-tappers for earth leads you're bloody kidding! Those Webbers are sposed to be about the best ay, so this customer is gonna be very happy with his amp. Sydney huh? I'm only about an hour's drive north of ya!
@@theguitaramptech Oh right! Yeah of course, if you're on the southern end of Sydney! No surprise there. Ya funny bugger! Let's just say I'm north of the Hawkesbury then! Tryin not to be too specific in a kind of paranoidish way. - Unlike yourself! I had a pommy friend years ago from Kogarah that I've lost contact with. He's probly gone 'home'. But yeah as they say - "I wouldn't be paranoid if everyone would stop looking at me!"
Hey Chris another detailed great video. I used to own a '77 2203 bought back new from the UK by my long suffering parents while on a holiday. Bought from Macaris London for the princely sum of around $240 AUD. Unbelievable I know but that was the price back then. Regretted selling it years later for a decent profit but really what can you do with a 100W fire breathing monster of an amp for playing around the house once your gigging days are done?
What wonderful parents! You're spot on, Robert. Where can you play 100w today? I haven't even played my 40w Brownface Concert for 17 years!! But at least we got to do it back then. I feel for the poor kids of today who will never know the feeling of being strapped to the front of a steam locomotive (aka a Superlead or a Twin on 10).
Fenders are very good amps! Only thing I don’t like is the upside down chassis! Valves operated like this going to shorten their life and toast the components sitting above! I.e. Capacitors,resistors etc! Any views on this? Fraser
Hi Chris, great video as always. Are you really sure the JMP 2204 and early JCM 800 2204 are different. I have to look into my JCM , but I think the pcb looks almost the same. Greetings from Germany Markus
Hi Chris, my good man! So great to see this video! When I start working on electronic noise issues, I start with a 'ground' up.approach. In the world of audio ground noise issues, reducing and isolating the DC ground resistances are very often the root cause of the issue. Inductance is not a significant factor at audio frequencies. Your analysis and implementation in a JMP-50 is the best part of this video (for me). And yes, Jimi with a Marshall and a Stratocaster is the ultimate test for this amp! Yea, he did not play JCM 800 amps. Congratulations on this video and you guitar playing!
Hi Chris, Denmark on the line....this were very informative videos for me, as I have two of the original Vibro-Kings that I try to maintain myself. They're both with 6V6 reverb drivers but born with different speakers (one Blue Eminence, the other Jensen Reissue) and there's small differences in the circuit, as they were revised a few times over the years...one only came with a single button footswitch for FAT, not a button for vibrato as the later versions. I have recapped both with F&T's all over the place and had som serious battles with hiss and noise at higher volumes, and various... The Vibro-Kings are like race cars and you need to keep an eye on them all the time - and quite some even give up on them because of reliability. But when they work, they're about the best sounding amps ever made...touch sensitive, three dimensional sounding and a reverb to die for. I also have two '66 Super Reverbs, Super Six Reverb, Dual Showman etc... and I know my way around in those classic amps, but like you show here, the Vibro-King is another animal - so for a guy like me that are not very good with schematics, your explanations of the circuit was very velcome, and I'm glad that I came across your videos....even though, I don't have any problems right now :-) But it made me want to open them up just to check some stuff.... Oh, and I also have one of the matching 2x12" cabinets.... but to me the 3x10 combo sounds better on its own... Thanks, Bjarne
Another fantastic video Chris. Thanks a lot. Rookie question. Why take the grounds to two separate stars instead of just one. Would that not be even better ? Cheers
In theory, you may be right, but when you consider that the Preamp is the most sensitive section to noise, because of the lower signal levels, and the power stage is the noisiest (closer to the rectifier and much less filtering than V1). Also in a Class AB power stage you have the added benefit of common mode rejection (with the OT) that you don't have in the preamp. That was bad grammar. Sorry, but I think you understand my ramblings.
That's a good question. I much prefer to solder my main earth points to the chassis. With an Al chassis we have no choice but to bolt, usually with a steel mounting system to Aluminium. I am suspicious of the galvanic potential that can cause corrosion/conductivity issues in an amp. I don't expect the resistance of Al vs Steel to be a significant difference. Good question. You made me think!
Good one Chris! I heard or read somewhere that the piano wire link between the pots was mainly to stop them rotating if their mounting nuts became loose? But I'm not sure. Does that link wire separately connect to chassis earth? - I couldn't see. What wattage iron do you use to solder the earth wires to the chassis? I bought an 80W iron from ole mate Jaycar electronics, which was the highest power iron they make, hoping it would be enough. I used to have a 250W iron with a 1 inch diameter copper tip! - Which unfortunately got incinerated when a firestorm burnt my sheds down, & nearly my house along with them. Those Vishay metal films sound like a great choice mate! - As do the fnt (?) filter caps. I like your idea of grinding down a metal nail file for the phone jack contacts. We won't tell the missus! Shshh! That original V1 was definitely kangaroo Edward, as well as not knowing the words! Did I miss the the point where you said a bit of assymetry gave nicer 2nd harmonics, but then you said the 27% difference in bias was no good? I missed the nuance there! Loose bolts all over the place was a bit of a surprise, but good thing you checked em & tightened em! Maybe a bit of nail polish might help ya reckon? Nicely done overall & you should have another very happy customer! Liked the "back in black" & "baby please don't go" sound test! - Noice!
Neville mate, you have made my day. My soldering iron is a 120W Weller. Yes, a bit of asymmetry will increase 2nd order, but its almost impossible to bias 27% difference without one valve being too hot or too cold....and too much mismatch can sound shyte to me. Thanks Neville.
I have a clone JMP 50 built here in NZ. Sounds great, but I am always looking for improvements or tweaks to taste. Grounding is something I'll check now. Cheers. So far all I have changed is I've split the shared V1 cathode, so it has the 0.68uF and 2.7K setup on V1b. I have also tried changing that coupling cap between the first two tubes. 0.0022uF instead of 0.022uF. I am not sure I'll keep it that way, plus I like the look of the mustard caps it came with. I've also tried various bright cap values. All pretty basic stuff. Maybe the biggest improvement was had by trying the various preamp tubes I have. Just looking for the least noisy combinations of them in all three slots. That and sourcing some tube shields for them helped with noise. I'd like to find a good 7025 tube. Supposed to be very quiet in V1 but still sound good. Once I got the preamp noise down, the presence control is less prone to oscillation when everything is turned up (still scratchy though, but that's normal for this design apparently). Power valves are Mullard reissue EL34. Seem pretty good so far. I have a pair of those old Sylvania 6CA7s like Van Halen used. Last time I checked they were barely within matched, so I do not like using them, plus I do not want to use them up for everyday use, because they are very rare now. It did not have a head cabinet. I ordered one from Ceriatone, but it does not look right. Ones that do look right from the USA tend to cost almost as much in shipping as the cabinet itself. Stuff that. Not sure what to do. Sometimes I think about converting it to 2204 spec, but then I think nah. Having a good sounding Plexi is nice to have, so why change it to something else is what I think. Then i toy with the idea of build a MKII master volume amp. A little above my pay grade yet, so i think I should build a 5F1 amp instead.
HAHAHA! You build a 5F1 after a JMP Plexi? No way. Yes its hard to find good modern production 12AX7s. I have had good luck with the TAD 7025s, but my favourite for V1 is a 5751. To my ear its a much better sounding tube than a 12AX7. Good luck with your fun amp journey!!
Oh no! Don't tell me I edited that out in my desperation to shorten the video. Yes, I changed them. If my memory serves me well, and it usually doesn't, I used TADs
Great job my friend. I have always been able to improve the noise floor on older Marshall’s by improving the grounding in much the way you did it. Cheers.
I bought the combo version of this amp new in 1977. I was new to the guitar and it was my first tube amp. Sadly, in 1978, I sold it to buy a solid state amp with more bells and whistles. Though I still have and use the amp I replaced it with, selling that 2104 is something I really regret. Not to mention that now it would be worth 5 times what I paid for it in 1977. Glad to see some still out there and being taken care of.
interesting you grounded the middle and presence pots to the reservoir cap ground. i never tried that. What would be the difference grounding those near the pots on a ground lug to chassis? (not to drill a hole for this amp as it is vintage)
Sure you can do a separate ground; it would be better than stock. The biggest improvement is just separating the preamp and power stages. Lyle @psionicaudio has an excellent video on grounding for Marshall amps. Check it out.
@@ampyamps I recorded this repair back in the Aussie summer (its mid-winter now), so I can’t recall amp specifics. However, I can tell you that earlier Marshall models did not have screen grid resistors. If this was the case here, I would have decided not to install them as changing screen grids can have an impact on the tone of the power stage. Thank you for noticing and commenting.
