You see I'm not going to remove the switch until I have a suitable replacement for it because the switch would most likely end up getting damaged while trying to take it out to measure the hole
Does anyone know the diameter of the hole for the on/off switch on an epiphone valve junior head?
Quote by AcousticMirror
maybe a soldano hot mod?

Thanks, checking them out now!
Update! After wiring in a pcb and two red leds, I shorted the attenuator bulb and with some crafty wiring (thanks to Mikey) the leds now light up indicating the bulb short and an assortment of resistors takes up the load.
All tested with my new multimeter! (the only flaw with my old one is it didn't like electricity)
Thanks guys
Quote by bubb_tubbs
Dumbass kids...

I'm retired.
Quote by Cathbard
Have you taken into account that the lightglobe has resistance that will add to the total impedance of the speaker? Even if it doesn't blow you are going to be putting added strain on the output.
What you need is an L-Pad of sufficiently high a power rating. Stop doing what you are doing now, it can only end in tears.

It's the natural compression I'm looking for and the same idea has already been used by amp manufacturers in the 60's,
I know what you mean by the bulb adding resistance but its a 3 watt amp and a small light bulb, I'm not going all Tesla on this, an amp tech friend popped around this morning and checked the wiring of it and had no objections, however he said I'd have to use a mathematical formula for total impedance if I keep the resistor in the circuit
Quote by Cathbard
With the exception of rectifiers, pretty much every pin is used on a socket. So how are you going to split it up into two?
No, you don't have double adapters for tube sockets - you add an extra socket if you need an extra valve.

I'm invisioning a double adapter for an electrical socket, only for tubes adding a socket takes time, knowledge, skills, this theoretical adapter would be plug and play or 'plug, plug, plug and play' as it were.
Quote by AcousticMirror
hmmm would be great idea.

you're not being sarcastic are you?
Something that turns one tube socket into two,
Does this exist?

I assume extra components would be required inside the adapter itself, but hey Bill Gates said xbox live was a stupid idea at first
Quote by Frood
Guitar George, he knows all the chords, but he's strictly rhythm, he doesn't want to make it cry or sing

Dire Straights - Sultans of Swing

...All the chords?
Quote by Zaphod_Beeblebr

there should be a sarcasm and satire button somewhere
Well as Barrack always says...


Nah doesn't matter, sure john mayor has never played a solo in his life

Now that I think of it you may enjoy classical guitar, doesn't have to be classical music but its played in more of a rhythmic style as opposed to lead
Quote by ragingkitty
I was gonna say Tung-Sols for the clarity and definition.

Honestly I'm not entirely convinced that just by plonking in some different tubes you get a whole new sound out of the same circuit, but if it works... .

No, no, you're right but I bought the amp used with some mods already made and
I've put in some more so I can understand why people are saying "NO it not do the bR00tz never!" but I'm using an extra preamp, some pedals and a modified circuit

No, new tubes will not give a valve junior really high gain, quite obvious,
Yes, modifying the amp in other ways can give a valve junior high gain, acoustic mirror has also shown this.

EDIT: one of the old tubes just red plated in a different amp no doubt the condition of the tube contributed to the lack of clarity
Quote by ECistheBest
oh ok nvm. good thing u got good results from modifications to your own taste haha

Ah no you're grand, a miscommunication, thanks though!
Quote by ECistheBest
yea dc coupling gives u awesome results that aren't so awesome.

so you're trying to maximize distortion. to do that, u can do few things. it won't lead to pleasant sound tho, but you can get more distortion out of it.

-jumper R6
-clip R7
-replace R3 with 220k
-replace R4 with 180k
-jumper the treble cap of the tonestack, clip R17 and R15
-for tonal properties, you might want to increase R18 to 270k, replace C4 and C3 with 2uF, 1uF respectively.

these are suggestions. doing all of the parts that increase gain will probably result in unpleasant sound.

Oh no, maximising distortion is not my aim at all My board doesn't conform to the schematic in some areas, R1 and R2 is one of those areas, in my amp they're reversed which caused some confusion which is why I created the thread.

But now I've done some more eccentric mods using parts of old amps and moving the tone stack and the results are great I just have to solder it all in because right now its croc clipped and then it's done
A neighbour of mine kindly offered me some old tubes out of a butchered/melted/raped mesa boogie head and by zakk wyldes beard there is a world of difference, its no longer classic rock crunch, it's leaning more towards djent, it is a bit too fuzzy but dialing back the gain fixes that and in d standard its perfect!

It is a blues amp (with more than a few crafty mods and tricks ) doing modern metal gain and I am extremely satisfied.

It's no longer a thick and bassy tone which was perfect for the bluesy stuff,
It's now tight and clearly defined and articulate with much more clarity in riffs and chords and there's a lot more high bite than before.
Quote by TheQuailman
Yeah, and I'm still telling you you won't make your tone any more metal no matter what tubes you put into the VJ. The only thing I could do to make one of my VJs sound metal was plugging it into a 2x12" cab and putting distortion boxes in front of it.

But fine, you just want good tubes. I like putting TADs in everything since mine stubbornly refuse to break. For a cheaper option, JJs are prefectly fine though. I'd say get a JJ EL84 along with a JJ 12AX7, and maybe a Tungsol and TAD 12AX7 to try and see if you can hear much of a difference between them (plus it's nice to have backups).

I have pedals chillax
fulltone ocd version 4, yes the worst in my opinion and a Maxon overdrive 808
Quote by TheQuailman
No.... no, that doesn't work. That will never work at all. There's a lot more that goes into a good high-gain tone than just distorting the living hell out of everything, and trying to get distortion out of a VJ will just make everything muddier.

You want the VJ clean and all your dirt from whatever pedal/preamp you're using.

hey I never said I wanted to turn everything to eleven, my set up as is can do the metal thing with good success but I want a little more gain at the high end and my tubes are gone microphonIc so I need new ones anyway
Quote by ECistheBest
i hope you didn't DC couple it.

what's R19? valve JR doesnt have an R19. o_O

Harley benton ga5h its a valve junior clone with a bass control so the parts are slightly different
dc coupling?
why would letting ac and dc through be bad?
okay what I've done is the equivalent of bypassing r15 on a valve junior is that dc coupling? I think it is
Quote by coolstoryangus

Well I could get the lend of a good Mic to record it if there's a demand for it, otherwise I'll upload a video to youtube via smartphone
Quote by Dave_Mc
oh ok.

I have no idea about that kind of thing if it works then cool

I know, its heresy
Quote by Dave_Mc
oh ok

jjs are a pretty good bet for a warmer tone, as PP182 said. compared to the stock sovteks, anyway.

what pedal do you have, if you don't mind my asking?

well I'm actually using a Marshall solid state combo going into the junior via the lineout and that goes into the marshalls speaker so thats where I get my distortion, reverb, delay, chorus, compression etc and before anybody says that a crap setup, I know it is but it sounds pretty good and my playing makes up for it
Quote by PussyPunk182
I'd revalve your junior with some JJs, a 12ax7 in the pre and whatever you want in the power section. Then get yourself a distortion pedal, probably not an overdrive because pushing this amp will just get you a heavy blues lead sound (probably a good one too).

Get a barber dirty bomb, I'd say.

Yeah I've used the amp stock with a boss eq and it was amazing! It was blues bliss!!! and I can't even play real blues!
Quote by Dave_Mc
there's no way a higher gain tube is gonna give you metalcore with a valve junior. you need several cascading gain stages to get you that.

best bet is to try a pedal or two...

Sorry I should have mentioned I have a pedal
I just want that BIT more gain not full blown death metal dimebag amounts of gain

you know something a bit darker tone wise
Quote by AcousticMirror
go back and do the things I told you to do.

I'm not trying to be a Dick or anything but what you've suggested can't be applied to the schematic, for example lifting the ground on r19, r19 is a fixed resistor lifting the ground side will create an open circuit, and lifting the ground on the bass pot is not going to bypass it (although it would on a normal tone pot)
The other suggestions I'm awaiting parts for.
I have bypassed the tone stack by connecting the positive and negative wires before they reach the tone circuit, and the volume increase through a 50w 12" speaker is monumental!
However, the schematic you provided was of great help, thanks again.
It would seem as though I have to order from the UK...which is quite the inconvenience....somebody prove me wrong!
Right now I have a Marshall preamp tube, I think It's a 12ax7 but it doesn't actually say and an EH EL84L which rattles and squeels -_-

So the Marshall is crunchy and that's about it, leads aren't brilliant, kind of like van halens brown sound with the frankenstrat, which is cool.

I want something with a teeny bit of fuzz so I could crank it and get some metalcore out of it like my curse by killswitch engage, which right now sounds okay with these tubes but I want...'more'

Also this the tone right now is very dark and I want some more highs

Someone suggested this to me:

Would this fit the bill?

ps I'm not looking for an exact copy of any particular bands tone but I like the early van halen tone I have now its just that's pretty much all it can do well, so id like to able to pull off some higher gain, modern metal stuff

any preamp or output tubes you can suggest would be much appreciated!
Quote by jof1029
the schematics im looking at show R2 in line with the input, and R1 going to ground. sounds like like your version of the schem has it the other way.

but to get more gain you want to lower the inline resistor, and increase the resistor to ground. it looks like people are dropping the inline resistor to about 22k and the resistor to ground is increasing to 1M.
so basicly, this:

So I snipped JP1, bypassed the first inline resistor (the one you reduced to 22k) and also bypassed R6 and R7 and removed the tone stack. The result?'s verrry loud...bassy, almost farty and the attack is extremley harsh....I'm probably going to undo everything except the JP1...unless Anyone can suggest better tubes for overdrive because this sound is terrible, right now I have a Marshall 12AX7 (with black writing) and an EH EL84L
here's a little piece of info for you guys, compared to an epiphone valve junior head a Harley Benton ga5h's resistors R1 and R2 are actually reversed!

So as invaderJim says bypassing R2 would ground the signal on an Epi but on the Benton bypassing R2 increases the amount of signal that is allowed into the preamp and R1 bypassed grounds the signal completely
Quote by Invader Jim
if you jumper R2, it will ground out the signal.

my knowledge of tube circuits isn't as good as it used to be but lowering R1 should increase the input level. it won't give you 'more gain' because this is all before the first gain stage. jumpering R1 may not be good for the tube or w/e. like i said, i'm quite rusty.

Okay thanks,
I've read multiple other articles that say jumpering R1 will allow the guitar's input to push the preamp tube harder, making the sound more distorted, I should have distinguished what I meant by 'gain', but you're right it will shorten the life of the tube.

Once again, it's Jim to the rescue!
Simple question

Apparently these two resistors cut the input signal in HALF!
I know R1 can be bypassed and many replace R2 with a 10k or 22k, but can they both be jumpered for more gain?

Thanks Lads.
Quote by AcousticMirror


replace r1 with a 1 meg resistor and switch the locations of r1 and r2 so that 1meg to ground comes first and then 68k into the grid.

better yet replace the 68k with a 47k or 22k.

you can jumper r7.

you'll need a grid stopper on the power tube. 1.5k connected to pin 2 of the power tube. you'll have to cut a trace so if you don't do it it's ok too.

lift the ground of r19.

You don't know how much that schematic has helped me! You Sir, are a genius.
Quote by AcousticMirror
lift the ground on the tone control.

I think* this is an active tone control because the lower you put it the more treble you have in the tone and vice versa, there is also a small pcb attached to the pot with components on it, will lifting the ground wire work for an active control?
Again, I'm not 100% sure it's active but it looks that way
I want the head to function as if it was an epiphone valve junior head in terms of how soon the sound distorts, because I've heard the Harley Benton has a lot more clean headroom due to the tone pot.

I don't want so much clean headroom,
even on full volume the sound is pretty clean.

So how do I get the head to work as if there was no tone control?
Pretty much anyone could put flashing lights in a humbucker.......but this is level of workmanship and efficiency is just awe inspiring
I'm using a lightbulb in series with my speaker to act as a cheap attenuator and compressor for my valve junior head, and it works nicely.

My only worry is that with the amount of playing I do the bulb is sure to burn out sometime, leaving the head powering an open circuit.

I have heard of wiring a suitable resistor in parallel with the speaker and light bulb but if the light bulb does burn out the net impedance will increase, will this damage the head?

Does anyone have any other ideas to prevent an open circuit from burning out the output transformer?

My idea is to run the power supply from the mains into a thermal fuse which would lie across the output transformer and in the event of the head being powered up with no speaker the OT would start to heat up and thus set off the thermal fuse,
Does anyone see any flaws with this theory?

Thanks in advance guys.
Quote by OldRocker
What would be better is the AC zip cord. Like those you have on lamps, radios, etc.

About those speaker wires, they may not be heavy enough to handle the current.

Thanks Matey, you saved me having to hack up a good cable!
Quote by Oldmonkeys
just use a paperclip rubberband combination... gives the best tone.


there is a reason they make speaker cables, get a real one

Does the colour of the rubberband matter? Because I only have green