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#1
Hey again fellow UGers,
Today I broke down and couldnt hold back my wanting to mod my Valve Junior. I decided to only do one mod today, but thats ok because its a good one .

I know your all like finish your pedals and stuff, but this only took up one morning so its good. Ok so what is it you may be asking. Well its a Gain switch. It goes between higher gain and lower gain.

Pictures (Sorry for a bit of blur, but you can make it out):






I plan in the future to do some more mods like to change the Fender Low style input into the Fender High style input for a higher input impedence and more sparkle.

Kerry
#4
Heres the soundclips!

1. This one is with the amp by itself. PRS Custom 24 Ten-Top on treble pickup. When the switch it down its on the lower gain, when the switch it up its on higher gain.
http://aronnelson.com/gallery/albums/album90/Alone.mpg

2. This one is using my built Marshall BluesBreaker (75% Gain, 75% Tone, 100% Volume), and my So Simple Compressor V2 (Compression Sensitivity 0% [This doesnt mean no compression, its about the same as 100%], Volume 100%). With my PRS as the guitar on the treble pickup. When the switch it down its on the lower gain, when the switch it up its on higher gain. This is one of my favorite tones I have gotten out of this thing!
http://aronnelson.com/gallery/albums/album90/With_Pedals.mpg

Kerry
#5
I am by no means an expert in electronics but it looks like the switch simply acts as a bypass for that particular resistor (the one you soldered to on each end) to give you the higher gain setting? Is that all you needed to do to achieve this mod?
Guitars:

Epi LP Standard HB W/ EMG 81/85
Ibanez RG470
OLP Tin Top

Amp:

Epi Valve Standard

Effects:

Custom Pedal Board

Boss DS-1 | Boss TU-2 | MXR Blue Box | MXR ZW-44 | DOD YJM308 | VS Jekyll & Hyde | Vox ToneLab SE
#7
It looks like he added a switchable jumper on R9.



If you replaced that resistor it looks like you'd just get a gain boost.


EDIT:
Which he already said I see:

Quote by call1800ksmyazz
Heres the soundclips!

1. This one is with the amp by itself. PRS Custom 24 Ten-Top on treble pickup. When the switch it down its on the lower gain, when the switch it up its on higher gain.
http://aronnelson.com/gallery/albums/album90/Alone.mpg

2. This one is using my built Marshall BluesBreaker (75% Gain, 75% Tone, 100% Volume), and my So Simple Compressor V2 (Compression Sensitivity 0% [This doesnt mean no compression, its about the same as 100%], Volume 100%). With my PRS as the guitar on the treble pickup. When the switch it down its on the lower gain, when the switch it up its on higher gain. This is one of my favorite tones I have gotten out of this thing!
http://aronnelson.com/gallery/albums/album90/With_Pedals.mpg

Kerry

Oops.

EDIT #2:
And he just posted again at the same time.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#8
Quote by call1800ksmyazz
I plan in the future to do some more mods like to change the Fender Low style input into the Fender High style input for a higher input impedance and more sparkle.

Kerry


I'm not sure about the epiphone valve jr (though I'm pretty sure this applies), but usually the input resistor is chosen to match the input to the first preamp tube.

Edit:
Looking at the schematic, you could replace the two 68k resistors with 1-33k resistor.
Last edited by greenbox at Dec 10, 2006,
#9
But I have heard that this amps input section is based on the low input of a Fender amp. I havent studied many Fender amp schematics, but this amp probably has a few things based off of Fenders.
#10
you might be thinking about the input styles between a isolated ground and attaching a 1-Meg resistor to ground from the input (atleast, I think that's what you might be talking about). Anyway, if you change the input resistor, you'll also get twice the gain (since the 2-68k resistor's act as a 34k input impedance with a voltage division of 1/2.)

Atleast, that's what I thought you were talking about, you might or might not want to do that.
#11
Thats basically what I am talking about. The mod is to take away the 68k resistor to ground, and replace the first input resistor (68k) with a 22k resistor. This changed it from the Fender Low input to the Fender High input, or as they say.
#13
your time is well spend modding it
a new OT is probably a good idea too,
and the gain, bright, and master volume mods are also pretty fruitfull
and you might go ahead and inprove the power supply filtering as well, along with a nylon input jack, to help with any noise you are probably getting

there is so much you can do with that amp in terms of modding though, thats why im getting one, for christmas

i'll be watching this thread..
#14
My next mod is going to be a Master Volume after the second half of the 12AX7 and before the power tube. This is so I can put the full preamp tube overdrive without the sometimes crazy powertube overdrive/saturation.

Standby switch really isnt needed in this amp. So I dont really need to waste a switch.

I am also going to do the higher impedence input when I open it up again.

The power supply fix has already been done in the new V2 Valve Junior Heads so thats no problem. The jack is also fine, but if I do change that, thats at the bottom of my list.

My dad suggested me getting a new speaker or cab for it. I think im going to get a Celestion (probably V30) and put it in my Hartke. Or we may go to a car place that puts speakers and stuff in cars, and see if they have a speaker box without speakers we can use to build a cab.
Last edited by call1800ksmyazz at Dec 11, 2006,
#15
you're not really changing the input impedance, you're actually lowering it, but what you are doing is removing the voltage divider (so you effectively get an extra gain of 2 in your amp)

same idea though. Although, for the longest time now, I've been meaning to make an octave down or a tube screamer. I've just been really lazy.

as far as the master volume pot goes, sounds like a good idea (i'm not entirely sure, but it looks like you could just replace the 220k resistor after V1 with a 250k pot or something. But i'm sure you know what you're doing.
#16
^-I am exactly replacing the 220K resistor with a 250K pot. That was my whole idea. I guess now it has been approved since you came up with that too.

Wow I just decided to try my Hartke 12" 60w speaker with my Valve Junior instead of my Hughes and Kettner's Jensen 10" 30w speaker. The difference is incredible.

The Jensen:
*More trebly.
*Gets tube overdrive when amp is on 25%.
*Gets full tube saturation when amp is on 50%+.

The Hartke:
*Much, much warmer and thicker.
*Extremely loud! Freaking 10 times as loud as the other speaker. I was playing at 25% volume with my BluesBreaker overdrive and Compression pedals, with my guitar at 2 volume, and now I have a headache from it!
*Absolutely NO tube saturation and barely any tube overdrive, even with an overdrive pedal.

Conclusion:
The Jensen can get a GREAT heavy classic rock tone with overdrive and compressor. The Hartke has an amazing clean tone with the overdrive and compressor and every note is easily picked up. However the Hartke has NO good heavy tones.

I am probably going to get a Celestion V30 or Greenback and mount it in a cab (I will probably build a cab) and then I will have a good selection in all of the tones I need!
#17
Maybe you could wire the amp to all of the speakers with a switch for each one...
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#18
Yea I keep going back to play through the amp. I just got the absolute BEST tone for classic rock through the Hartke cab. I can get Marshall Plexi-like tones from this baby. Then with the H&K's Jensen speaker, I can get the oldschool metalish tones.

I just realised that this amp could possibly be one of the best I have tried with my pedals backing it. At least I know that I have found my tone. And finding your tone is a long and hard journey. Well... making pedals is good because it adds to your personal tone and you find what you like
#19
Well anyways... I did it. I spend the last few hours adding the Master Volume, and fixing the Input resistors to give a higher impedence and a clearer, sparklier sound. This input mod makes a hell of a lot of difference on the amp's muddy/bassyness when clean. Its not that bad standard, but a lot better with the treblier sound.

Heres where I removed R5 (220K) and replaced it with a 250K pot. Thats the Master Volume and comes after the second half of the 12AX7 preamp tube.

Heres where I took out R2 and R1, the input resistors, and replaced them with a 22K resistor and a 1M resistor.

Heres the new front of the amp. Yes I am going to get a new Master Volume knob. This is all I have at the moment.


The new, triple modded VJ is awsome... Whats comming next? I dont even know yet...

Kerry
#20
Aw sweet i would never trust myself to mod a amp unless it was something shitty. But good job Kerry
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#21
Thanks! I was scared at first, not because of high voltages, but because I didnt want to screw it up. But I did the first mod and got addicted. Its not extremely hard to mod this amp, but what makes it incredibly hard is that theres so many wires going to the board that its hard to get under it even after you take off the screws. But in time I managed...
#22
youre gonna need a intervention soon Kerry if you dont stop
Quote by rabidguitarist
I even tried dressing up as a fly myself, and throwing myself out of the window in the hope that they will follow me. But to no avail.

Quote by daytripper75
we have a Llama forum, and still no drum forum.
#23
yea kerry get off the mods

get professional help man, nobody wants to see you go this way
lol

kool beans
#24
Heres some new sound clips with various built pedals and pickup switching to show split humbuckers (single coils) and humbuckers with the amp. Settings can possibly be seen from the video. Guitar Settings are always at Volume-10, Tone-10 unless otherwise noted.

1. http://aronnelson.com/gallery/albums/album111/BluesBreaker_and_SHO_1.mpg
Marshall BluesBreaker into my Vintage Boost (MOSfet). Pickup switching in order: Bridge Humbucker (PRS HFS), Outside Single Coils (Parallel), Neck Humbucker (PRS Vintage). Nice crunch, cranked tube amp tone. I realised that by setting the Volume on the BluesBreaker back, you can get warm tube tones.

2. http://aronnelson.com/gallery/albums/album111/BluesBreaker_and_SHO_2.mpg
Marshall BluesBreaker into my Vintage Boost (MOSfet). Just the lead from Panama.

3. http://aronnelson.com/gallery/albums/album111/BluesBreaker_and_SuperFuzz.mpg
Marshall BluesBreaker into Marshall SuperFuzz. Pickup switching in order: Single Coil (Volume on 3), Bridge Humbucker (PRS HFS), Outside Single Coils (Parallel), Neck Humbucker (PRS Vintage). Some rhythm with the nice vintage/classic fuzzy crunch. Then a little bit of neck humbucker thick lead at the end.
#25
i kinda want to buy one of thoughs and mod it so it has 7-12axz tubes and possibly an el34 but probaly not the el34, i really like yours though i think maybe a bright switch and a dark switch would make yours possible the best lil tube amp for under a houndred bucks, actualy it would rival 300 buck amps
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#26
^-You mean 12ax7 tubes? Or do you mean you want to put 7 12ax7s in it? :P You cant put in a EL34 without some major surgery to this thing. It has totally different pinouts and all.

I think a bright and dark switch would make this thing awsome. Once I think of a good idea for one I will put it. And I think this thing already rivals a $300 amp. I would buy this thing for $200 stock if that had been the price and I knew what I could do to it.
#27
what about adding an EQ, a standby switch, using different tubes and more interesting stuff like that?
#28
What about puting in a switch to take it from pentode to triode? I hear thats pretty easy to do and that in the 3 watt triode mode is supposed to sound much warmer and more midsy. I have no idea how to do it mind you.
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#29
Quote by t heff
i kinda want to buy one of thoughs and mod it so it has 7-12axz tubes and possibly an el34 but probaly not the el34, i really like yours though i think maybe a bright switch and a dark switch would make yours possible the best lil tube amp for under a houndred bucks, actualy it would rival 300 buck amps

Putting in that many tubes would probably go past the PT's current rating. Adding an EL34 isn't gonna help.

You could possibly add one more 12a*7 though and stick in some reverb, that would be very nice. I'm thinking of buying one and doing this...is there enough room for a tank in the back 1800?
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#31
you should put in some trimpots for those mods, instead of just a fixed resistor

that way you'd get adjustment
on/off and everywhere between
#33
what other mods have you been doing/ could one do to this amp to make it sound better/give it more versitility?
#34
Cords idea on a triode mod for the EL84's is a good one. I'd add a switch as you probably won't want it on all the time. You should get a somewhat darker tone, but it's got balls for sure. Sounds nice with a Rangemaster.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#36

I had this around on my HDD. That should do you.

Btw, you are discharging these caps first, aren't you?
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#38
Quote by That_Pink_Queen

I had this around on my HDD. That should do you.

Btw, you are discharging these caps first, aren't you?


ha
why discharge the caps first?
getting shocked by filter caps is good fun


friend of mine's uncle got shocked by a millon volt cap bank he was useing for a pulse laser (like in the '80s), he doesnt remember though
but he almost died, had memory loss, the whole thing


so the lesson to be learned:
always discharge your filter caps kids
#39
^-Naaa. I love waking up the next morning in the middle of a burned down house from a soldering iron left on when I was shocked and dropped it on the carpet therefore causing the house to become ablaze and kill eveyone but me who got an incredibly powerful shock knocking me out

I know, what a sentance.
#40
what a sentence indeed

of course, the 60hz coming off your wall is worse in some ways, like how it grabs onto you, and how 60hz just so happens to be what your heart runs at
its one of those things thats going to happen eventually, ive got three times under my belt, none of which involved working on electronics