2550x Trouble shooting

[Jaymz77]

I thought i would start a new thread about this since it is not longer a build, its trouble shooting.

For some weird reason, the amp works fine, until you crank the clean gain, then it gets a fuzzy type distortion (almost like your radio sounds when its not quite on the right frequency) and loses volume. The volume part even comes and goes to an extent.
It was suggested that i might have a bad solder joint and to go through and check them, which i have done and the problem is still there.
All this started 1 week ago when i accidentally unplugged the cabinet with the head still on, it may have had some signal go through it but only at low volume and only for 5 seconds. After that the amp was humming badly, so i turned it off and let it cool. It then came good.
The next night the problem was back.
I managed to trace the hum to a weak earth connection so that is now solved but this crapping out with the clean gain cranked is still there.
If i leave the gain at 9 o'clock like i usually do the amp is fine, it is also fine on the lead channel where there is MUCH more gain on tap.

Im really at a loss with this and desperately need some assistance.
Cheers

[SILVERGUN]

Hey jaymz,
Good luck with this.....we all know how frustrating troubleshooting can be

There's a couple things that you should do to speed up the process.....
- Bring over the schematic from the other thread
- Show us the actual layout you wound up using
Most important:
- Get us some close up, in focus, hi resolution pics,,,,especially in the area around your input circuit (jacks, preamp volume pot, etc. etc)

Anyone who stops by to help will want this stuff.....I just stopped by first

[stratele52]

Did you check output tubes ? 

Transformer ?

These are the first ( and only? )  damaged with no speaker.

If good , check Phase Inverter circuit .

[Jaymz77]

I'll have to post pics and schem tonight. Can't do it from work.
I thought power tubes, but would it present itself on the lead channel as well? Lead channel has heaps more gain and it's fine. Tranny must be fine too
Everything works fine EXCEPT when on clean with the gain cranked.

[SILVERGUN]

I thought power tubes, but would it present itself on the lead channel as well? Lead channel has heaps more gain and it's fine. Tranny must be fine too.

You are thinking correctly......if the problem was further "downstream" (PI, power tubes, OT), then yes (based off of the 2550x schem. that was posted),,,,it would/should affect the lead channel also....
The fact that it doesn't,,, helps narrow your focus through the first stages.....start there, triple check everything and post the pics

These guys can fix anything.......don't start overthinking and looking at parts of the circuit that aren't directly connected/related to that specific area.....the fix is usually a lot easier than we make it out to be.......finding it is the tricky part

[Slimtim]

Bad res. or cap. on the clean side maybe?Or maybe that tube is going out that runs there.

[Jaymz77]

Thanks guys.
I've had everything from bad solder joint, to bad cap/ res, to tubes, to ot.
That is a big range.
I'm a bit frustrated that I don't know enough to diagnose myself without help.
From what I can work out, I have contradicting symptoms.
This only happened after hot plugging the cab, yet that would suggest the problem is in the output which would mean that it's there regardless of channel or eq settings. But it's not.

Another symptom I didn't mention is that when the amp is on and you switch to standby it kills the sound, as it's supposed to, but then when you turn the power off it hums through the speaker. With standby off! Weird.

This is all made harder by the fact that's it a matter of days before everything is closed. I'm thinking I might just grab some power tubes and if it's not them I have a spare set. At this time of year I would rather not spend any unnecessary money, but I want to be able to play it while I'm off work!
AAARRRGGGHHH!

[SILVERGUN]

1)I'm a bit frustrated that I don't know enough to diagnose myself without help.

2) From what I can work out, I have contradicting symptoms.
This only happened after hot plugging the cab, yet that would suggest the problem is in the output which would mean that it's there regardless of channel or eq settings. But it's not.

3) Another symptom I didn't mention is that when the amp is on and you switch to standby it kills the sound, as it's supposed to, but then when you turn the power off it hums through the speaker. With standby off! Weird.

4)This is all made harder by the fact that's it a matter of days before everything is closed. I'm thinking I might just grab some power tubes and if it's not them I have a spare set. At this time of year I would rather not spend any unnecessary money, but I want to be able to play it while I'm off work!
AAARRRGGGHHH!

I numbered your issues so it would be easier to address:
1) EVERYONE needs help with this stuff.....there are regularly posted troubleshooting questions from guys who have many amp builds under their belt.........you picked a mid-complicated circuit to build, so unfortunately your learning curve is gonna be a big one

2) Yup, but you'll have to diagnose and fix them one at a time,,,by dividing and conquering the schematic

3) It's VERY important to mention everything........there could be a big clue in the smallest detail

4) Stay patient and let us help you fix one thing at a time until it's done.......don't freak out and just start tearing it apart (we've seen that before, and it won't solve anything)

From here out just make concise accurate reports and directly answer the questions that are going to be thrown at you.....pictures will tell us a lot....don't be embarrassed....don't try to fix it by yourself....

If the amp hums continually after you turn the power switch off,,,,then you possibly have that switch miswired,,,,and I would start there
If it only hums for a short period of time after you switch it off,,,,,that might be the length of time it takes for the caps to discharge
Troubleshooting 101:
-The amp cant hum indefinitely without power being applied to it = power switch wired incorrectly OR power cord wires are shorted to something they shouldn't be

When troubleshooting off of a schematic, it makes sense to separate sections of the circuit to isolate issues.....
Start here and figure this part out, confirm all connections, and ask any questions you might have.

Good luck and BE SAFE

[Jaymz77]

Great response, thanks heaps.
The supply side of things is fine ( however I will double check) I am actually an electrician.
That being said I am an electrician, not an electronics tech so my Achilles heel is my component level knowledge. And I don't pretend to know much in that department, just the basics really.
What I find I struggle with is knowing which components do what job in an electronic circuit like an amp. That kind of knowledge is what would make trouble shooting easier.

As for the bit about the hum on power off, it's a couple of seconds worth. But I don't recall it happening before this issue.
Do you think it's worth me grabbing some tubes before the shops close for Christmas, or is the tubes being the problem a low likelyhood?

I will post some pics and schem when I get home. Damn work computer.

[silverfox]

I'm new at this so keep that in mind.


Save the money on the Power tubes. If it works fine on one channel then I don't see how it could be the final output. Do you? That's like replacing the differential when there's no power in reverse but the forward gears work.

Where is there a negative feedback connection from the output back to the phase inverter connected.

JMZ77 Don't do this until someone with more experience confirms it is a good idea. What does the Forum think of this idea: Lift the 100K resistor in the feedback circuit and see what happens.

I did a search of your symptoms and came up with someone else that built perhaps the same amp you have and from the same information. The schematic looks the same as the one you posted in your prior topic. Check this page for similar problem and the ultimate solution.

http://forum.metroamp.com/viewtopic.php?f=7&t=23389

Silverfox.

[Jaymz77]

Thanks mate.
 I wish I could tell you where the nf is but I don't have a clue!

I kind of liken myself to a pianola. Just feed the paper in and music comes out. Ie, give me a plan and I'll build anything, just don't ask me to explain how it works!

I'll have a read of that link.
Cheers

[SILVERGUN]

1) The supply side of things is fine ( however I will double check) I am actually an electrician.
That being said I am an electrician, not an electronics tech so my Achilles heel is my component level knowledge.

2)As for the bit about the hum on power off, it's a couple of seconds worth. But I don't recall it happening before this issue.

OK...good
1) As you continue to rule out sections of the circuit that ARE wired correctly,,,,use the schematic as a guide,,,and highlight the parts that you check and confirm......move through the circuit from the supply, through the power transformer, rectifier, and highlight everything as you go until you work your way to the root of the problem............don't guess and don't believe in magic  

2) Your filter capacitors store power while the power and standby switches are on.......when you turn the standby switch to the standby position, you are interrupting the B+ supply, and the caps will slowly drain that stored power to ground
If you wait a minute after putting the amp in standby,,,and then switch the main supply power switch off,,,you might not hear the hum because the caps will have already discharged,,,,BUT if you hit the standby and then immediately hit the power switch,,,you could be hearing the hum for the duration of the time it takes for the caps to discharge......that might explain why you didn't hear it before  

Sorry I don't have much time to go further,,but there are guys here who know much more than I do.........someone will step up...
It is my humble opinion that anyone who builds an amp has a responsibility to understand a schematic of that amp, and be able to service it,,,,,so this is not a bad thing,,,just a necessary learning experience.
 

[silverfox]

The 100K resistor is the one connected to the Presence Pot at one end, and the 4 ohm tap on the output transformer at the other end of the resistor. I used a layout from the WEB for your amp. It looked like the one you posted here the other day.

Disconnecting this circuit may make the amp sound slightly different so don't be surprised if that is the case. Again, the reason for doing this is to see if the problem is related to that part of the circuit. Just lift the 100K resistor at one end and that will disconnect the circuit.

If you have read the page listed, there are some wiring errors mentioned in the layout and construction. That may be what the problem is.


Does the problem described on the referred page above sound like your problem also??

Silverfox.

[Jaymz77]

Yeah i read that thread and it does kind of describe my issue in the sense that it sounds like a dying battery.
OT primary wiring is ok. 150 odd ohms pin 3 to pin 3, 88 odd ohms centre tap to each pin 3.
I tried lifting the 100k resistor and it made zero noticeable difference to the tone/ sound of the amp and the problem is still there.

Here are the drawings i used.

[TIMBO]

Hey James, I can confirm that the schem is good and that I used it as well
http://www.el34world.com/charts/Schematics/files/marshall/25aniv_silverjubilee_25_50w_2550.pdf
It matches the marshall one as well.

The only changes is the extra gain pot and the preceding coupling cap is changed from .022 to .033.

I just talked to the guy that has mine and has it set at "10" cause that's where it sounds best, sorry 

I would be unusual for a pot to be bad so if you can swap the wiper connection from the clean to the lead just to rule out the pot being funkie

[Jaymz77]

Will do.
Im off to my lesson now so ill try later.
I just swapped a few of the HT wires to some of a bigger gauge. not so much for the gauge of the wire but for the fact the insulation has a higher rating.
Nothing.
Im starting to think its a tube because it only happens after a minute or two, i.e. warm up  time.

[stratele52]

Everything works fine EXCEPT when on clean with the gain cranked.

I did not read that before .

If lead clean work , it is not the tube or OT

If it is an hand made amplifier  there is a good chance that several errors are present due to lack of experience.

A revision in detail of all solders and  wiring for breakage is required.
The problem in Standby and overdrive seems to have no relationship together

[SILVERGUN]

Hey James, I can confirm that the schem is good and that I used it as well

That's extremely important, because without a confirmed schematic you have no solid basis for your troubleshooting

I tried lifting the 100k resistor and it made zero noticeable difference to the tone/ sound of the amp and the problem is still there.

OK, good....that means you have eliminated the NFB circuit and you can highlight it and move on

Here are the drawings i used.

Are these an exact representation of YOUR amp?.....if you've made any changes we will need to know in order to amend the schematic

Try to get those pics up, and hopefully we'll be able to see where the problem is  
Another step that you could take would be to post short videos of the problems as they occur.....that'll get us as close to working side by side with you as possible....

Here's something for you to try: (all I am doing is giving you a visual confirmation of the caps discharging, in relation to the hum)
- WITH THE AMP OFF AND YOUR SAFETY GLASSE ON, Take your multi meter set to DC volts and connect the black lead to ground (clip it on so you don't have to hold it) , and clip the red to the area circled on the attached pic of your layout......you will be monitoring the B+ voltage we were talking about earlier
- With those 2 leads clipped in place (no hands), switch on the power, wait, then switch the amp out of standby-----mark down that voltage (you should be seeing your full B+ voltage)
- Then after the amp warms up a bit,,,,switch the amp into standby and then immediately switch the power off----while watching the meter
- Does the hum you hear after the power switch is off seem to match the voltage dropping as you see it on the meter??....and does the hum lessen and slowly subside as the voltage drops towards zero?.........get it?

RIGHT NOW WE ARE ONLY TROUBLESHOOTING THE PROBLEM YOU STATED ABOUT THE HUM WITH THE POWER OFF......without a solid, properly functioning power supply it won't make sense to try to solve the clean gain problem.

Divide and conquer Mate  

[Jaymz77]

Thanks again for a great reply.
I will get pics up ASAP, video too if I can. I have my bum hanging out as most of us do at this time of the year (Aussie slang for busy busy busy)

The drawing are a complete representation of my amp, I have even kept the layout as depicted.
The only changes are that I uses desperate switches instead of push pull pots, I have added a foot switch jack in parallel to the rhythm clip switch to make it foot switchable and I think I reversed the contacts on the relay so that the indicator led on the panel is ON when in lead mode. (Or it might have been that I connected them back the front to begin with and then corrected it, can't remember how it's supposed to operate). I don't believe these changes would affect the amps tone etc.
Otherwise it's as drawn.

I will try your suggestion tonight. However, last night when I upgraded the wires for the HT part of the circuit and tried it, I didn't hear the hum on shutdown. I will confirm tonight because i was on my way out at the time.

Cheers for your help.

[Jaymz77]

Well...
Im home early today and i thought i would try what Timbo suggested and swap the wipes for the gain pots to see if the clean gain pot was dodgy.
It SEEMS to be ok like that. I don't want to speak too soon (knock on wood, rub a Buddah's belly) but that MIGHT be the problem.
That being said, the problem didn't reappear on the lead channel as you would expect when i swapped the wiper leads.
All i can think of is that maybe that channel is so distorted that its harder to hear. Not sure. But even the volume dropping thing didn't seem to happen. Weird.

Anyway i will keep you all posted and report back when i have worked it for a bit longer. The issue would normally present itself within a minute or 2, i just played for 10 and it seemed ok. I mean, there was a bit of crunch there but I'm pretty sure it was within the normal range considering the gain was cranked. Im sure if i plugged my Les Paul in there would be more crunch.

Anyway, fingers crossed.
Ill chuck some pics up anyway in case we have to revisit this.
Don't pick on my work too much, this is my first amp 
Oh, and that last post should read "separate switches", not desperate switches, damn auto correct.

[Jaymz77]

The forum won't let me upload anything over 1600kb.
I haven't had such low res pics for 10 years. They would be too small to see anything on

[TIMBO]

Hey James , you need to compress your pictures down to under 600KB per picture. I have Microsoft picture manager that can do it, do you have anything like that.

[Jaymz77]

Here we go. but aren't they a bit small to see much?
Anyway your gain pot wiper suggestion seems to have worked Timbo... Fingers crossed

[Jaymz77]

more

[Jaymz77]

more

[Jaymz77]

Don't pick on my newly work too much!
Most of the untidiness is due to me scratching around looking for this problem.
But fingers crossed it seems ok

[TIMBO]

James, Those pics are great.

[Jaymz77]

Cheers.
The board came out pretty good except for the bit around the bias pot. The pot i used was a different shape to the one in the layout and i had already drilled the holes for the turrets, so i kind of had to modify it on the run.
I was going to route the wires all nicely etc, but thought i might get crosstalk. The twisted wires you can see are the heater wires, relay coil wires and led wires. Everything else is loose. Makes working on it easier too.
I made a cabinet, got some tolex to match my Mesa cabinet and it looks good.
Just have to get the Mesa leather corners and the faceplates made. Going for laser engraved stainless faceplates.
As a bit of a joke, i called it the JRM2550x (JRM is my initials) and put my signature where Jim Marshall's would normally be!

[Willabe]

but aren't they a bit small to see much?

Heck no!

Hover over the picture and click they will open up very large. Or click on the title under the picture and it will open up full without having to slide the picture around to see everything.


           Brad      

[SILVERGUN]

You did a great job with the pictures Jaymz.....
Don't worry too much about how it looks, especially if it's just for you,,,the most important thing is that it works properly and sounds like you want it to sound.

Let us know if there is still a specific problem(s) to be solved.....if there's something still not right,,,only you will know

But other than that, just CRANK IT, and be proud of what you made
 

Make sure to post some pics of the completed cabinet when it's ready

[Willabe]

Don't pick on my work too much, this is my first amp  

Pick on what? It looks real good and for a 1st amp it's great!

I think it's safe to say that most guys build a Champ or tweed Deluxe for a 1st build, I did, 5E3. You chose a pretty big amp for a 1st 1 to build.

You have nice evenly twisted pairs of wires and your R's/C's look good on the board.

There's some wires that look like they could be shortened up a little and some of your solder joints are a little messy but those things come with more experience. As you build more you'll get better at those things.


             Brad      

[Jaymz77]

Thanks for those kind words guys.
Ill post pics of the finished product.

[Jaymz77]

Right, this is really starting to shit me.

Amp has worked fine since last post. I ran my tv through it for a few days to burn everything in, but it made no real difference to the sound.
So then i decided to try a few of the mods i have seen to see how they effected the tone.

1). When i built it i could not get Malory's in a couple of values so i used what i think was a Malory copy. I have since tracked down a couple of these values so i replaced the caps in question. I was not expecting to hear a difference, i just wanted it to be all Malory's.
I know when you make changes you should only change 1 thing at a time, but since this Malory cap change was planned regardless i decided to remove the bright cap while i was at it to see how it sounded.
All i can say is WOW, what a difference. The clean channel was always WAY WAY WAY too bright, now it is fantastic. Interestingly, the 2550x schematic uses a 1000pf cap for the bright cap. Most forums i have read say that Marshalls use 470-500pf bright caps. Wonder why the 2550x is double the value? One planned mod is to try a 470pf cap there to see how it sounds.

Anyway, i class this mod 1 as successful.

2). With all the talk going on about different circuit revisions in the Jubilee, i decided my next mod would be to convert to the new revision.
The only differences seem to be slightly different values in some locations (people with much more experience than me seem to think these won't make any audible changes), slight differences in the bias circuit (which should have no effect on sound) and the newest version does not have the 47pf cap across V1.
So with the removal of the V1 cap being the only difference that should have an effect on sound i decided to try it.
I have to say my initial impressions are that it doesnt sound quite as good without the cap, but i don't have enough time on the amp in this state to make a firm judgement.

The main reason i don't have enough time on it is because THE PROBLEM THAT STARTED THIS THREAD IS BACK!!!!! Bloody Hell...

Its doing that thing again where if the clean gain is wound up past 3 o'clock the signal deteriorates over the course of a few minutes to become very grainy and harsh (almost like a pedal battery is dying, as someone else described) it also loses volume.
I tried swapping the wiper wires on the 2 gain pots as Timbo suggested before and it made no difference (when previously this solved the problem)
I poked around with a few solder joints that didn't look as nice as some of the others AND THIS MADE IT WORSE!!!!

This is really getting disheartening as i am in love with this amp when its working right.
If anyone can assist with this i would greatly appreciate it.
I thought i had left this issue in 2013...

[Willabe]

I tried swapping the wiper wires on the 2 gain pots as Timbo suggested before and it made no difference (when previously this solved the problem)
I poked around with a few solder joints that didn't look as nice as some of the others AND THIS MADE IT WORSE!!!!

Sounds like bad solder joints.


           Brad     

[Slimtim]

Are you using shielded wire?

[Jaymz77]

Bad solder joint seems the obvious but i have checked and rechecked them, so i don't know...

Shielded wire? Yes, but for the signal path to and from the preamp tubes only, not to and from the pots.

But you know the ridiculous thing? Its gone this morning...
I fired it up to play around with it and it was not doing it. The only thing i did differently this morning was that i slowly wound the gain up (searching for a particular tone) until i ended up finding my tone with the gain on max and still no issue.

Its weird. Unless it was too late last night and i was hearing things. Otherwise there is some sort of intermittent issue there.
Any suggestions?



Has anyone ever noticed how, besides almost taking your head off with its brightness, the removal of the bright cap changes the gain levels/ performance? With the cap i had to have the gain around 3 other wise it started to break up too much, now i can have the gain cranked (when the issue is not present) and it just gives that beautiful warm, glowing, ever so slightly breaking up, mid rangey, gainey Frusciante-ness. It did take a little bit of balancing to get the warmth and glow without too much punch on the bass strings when you strike them a bit harder.
Anyway i seem to be closer than i ever have been before (which is more or less spot on) to what has always been my hardest tone to nail to my satisfaction.
Some people seem to be able to just fall into that tone. For me it was always a struggle.

[Slimtim]

Yep max or close to it is the sweet spot for the dirty gainy stuff.Don't you just love tube amps?

[TIMBO]

Hi James, I ended up putting a 390p in that bright cap position. Just a thought on your problem it may be a resistor that once warmed up breaks down and for that to happen it could be a larger wattage power resistor 

[Jaymz77]

Thanks Timbo, ill keep it in mind if the issue returns.
Im liking the amp with no bright cap at all. I still have the treble on about 4.

[Jaymz77]

Well its back... Again...
I spent a few hours playing the other day and it was ok. Having said that, i kept thinking i was hearing the issue come and go but could never confirm it. I thought i may have been imagining it on this occasion.
Now, tonight i fired it up and the problem was back within a few mins.
This is killing me.

Is there some way i can post a sound clip on here? That might make it easier to pinpoint

[SILVERGUN]

Is there some way i can post a sound clip on here? That might make it easier to pinpoint

Most guys here get an account on a music hosting site like soundclick or soundcloud and then upload sound clips there and just put links to the clips here....
It might work well in your case so that we can here what you're hearing

[Jaymz77]

I tried to record a clip tonight, but do you think the silly thing would play up? NOOOOO!
Stay tuned, i post something when i can...
Cheers

[Jaymz77]

Im still working on getting a sound clip of this issue...
But i have some new information that might help someone smarter than me figure this out.
I have recently been experimenting with my signal chain and setting the amp up for my different guitars. I had been running my Boss ME-50 through the effects loop since my last post and apart from sounding friggin amazing, the issue with the amp had mysteriously vanished.
Today i was experimenting with having the ME-50 up front to see which way i preferred (i had notice the tuner function wasn't liking a bit of noise). When i tried it this way the amp was noticeably louder and within a few minutes the issue had returned.
I then removed the ME-50 all together and went straight in, problem still there and volume still louder. I have now gone back to having the ME-50 through the loop.
For some reason it seems as though something in the amp is crapping out with too much signal. When the signal is cut a little bit, like when i have the ME-50 running through the loop with a bit of compression (even with a bone dry signal) it seems as though the signal is cut just enough for the amp not to crap out.
The amp does seem warmer with the ME-50 through the loop too. Even with nothing on.

I guess i am happy that i can use the amp and get the sound i want in a way that doesn't make it shit itself, but i really want to know what this damn problem is!!!
I should be running the ME-50 up front but i can't and it really bothers me knowing there is a problem there.

Oh and its started making a POP after a minute or so of turning the standby on. Only does it once each time....

[TIMBO]

Hi James, I'm no real expert on this and I don't know the function of ME-50, but most of the guys use TIME based FXs in the FX loop. Also the FX loop in the Jubilee although appears PASSIVE could actually be an ACTIVE type as it is jammed between the two triodes of the TS driver.
In most builds the FX loop is just before the PI. So your FX may be increasing the signal too much 

[Jaymz77]

Timbo, the ME-50 is a multi effects unit.

The funny thing is, the ME-50 seems to CUT the signal when connected through the effects loop.
When connected up front, or when not connected at all, is when the problem appears.
So there seems to be too much signal in its normal state.

This is real weird.

[Jaymz77]

OK...
Here is a link to a video i recorded today.
1) ignore my lame ass playing, it was just for the recording.
2) if anyone cannot understand me, let me know
3) the problem seemed to appear a touch quicker than normal... <1min - 1min
4) in the second part (with the effects in the loop) notice how much warmer and smoother it sounds, as well as quieter. Only a bit of compressor and a touch of reverb used.

If i think of any other points i will add later.
Here is the link...

http://youtu.be/9hQg6eYq93U

I really hope someone can assist with this...

[Jaymz77]

Bump...

[SILVERGUN]

Hey Jaymz, I listened to your clip and nothing stands out to me as "that's it for sure"

If it were in front of me, I would take an oscilloscope and probe it in the signal chain in different spots....watching the wave form....even use a dummy load instead of your speaker, so you don't get a headache

It would be very helpful to have a signal generator, so that you wont have to play and you could just concentrate on finding the issue...
They make simple apps that you can use on your smartphone that will just generate a simple sine wave that you should try to get matched to the amplitude of your guitar signal...

It's the best not-too-technical approach to getting to the bottom of your problem.
Only problem is, you need a scope....they do have apps for those as well (I have no experience with using them).....so with 2 phones you "might" be able to see what's happening 

[Jaymz77]

Thanks for the reply.

Can you actually hear what I'm talking about tho?
I wasn't sure how clear it came through in the video. After all it was recorded on my phone...

It's starting to look like I might have to take it somewhere. I have access, through my teacher, to a guy named Pete Reynolds, who builds the "Reynolds Valveart" boutique amps here in Sydney. He is a bit of a guru who should be able to sort it if he is willing to have a look.
I would really like to solve the issue myself to save money and learn something at the same time but it's looking like I might have to submit.

Cheers again.

[SILVERGUN]

Can you actually hear what I'm talking about tho?
I wasn't sure how clear it came through in the video. After all it was recorded on my phone...

It's starting to look like I might have to take it somewhere. I have access, through my teacher, to a guy named Pete Reynolds, who builds the "Reynolds Valveart" boutique amps here in Sydney. He is a bit of a guru who should be able to sort it if he is willing to have a look.
I would really like to solve the issue myself to save money and learn something at the same time but it's looking like I might have to submit.

Yes, I can hear enough to know that you do have a problem...
Look at it this way,,,if you're going to want to do this more in the future then I would highly suggest that you take the money that you're going to pay someone else to fix your amp,,,,and buy a scope off of ebay, and learn how to use it....(it's not that tough)

If you need a quick fix, then pay a pro....if he's reasonable, he might be able to look at it and tell you how to fix it