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My Valve Junior has arrived, lets talk more mods!


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Well my Valve Junior finally showed up this morning. I've been waiting just over 3 weeks, the seller was a bit slow, and the address apparently got ripped off the box, so it was returned to them and they had to send it again. Still, it's here now, and it seems in good nick, just needs a bit of a clean.


Plugged it in, and wow. Not a good wow either. The sound that came out if it is completely uninspiring! Perhaps I expected too much. And of course my other amp is a Peavey Classic 50, which is in a completely different league. And it would be just my luck that I find some fantastic settings on the C50, and the VJ shows up the next day so it probably seems more average than it is.


It's just muddy, and undefined. especially when you crank the volume up. I didn't expect it to break up as much as it did, so that's a positive, but the negative is that it seems to get muddier the more it breaks up.


So I definitely want to make some mods now. But first I think it might be a good idea to identify just what model I have. The serial number is 04068358, can anyone tell me what model I have from that? It has one 4 ohm speaker jack in the back too, I think the more recent ones have 4, 8 and 16 ohm jacks do they not?


I think I'll undertake most of the mods on this site, they seem like good, simple improvements to make, and as I said, I don't want to fork out too much cash on it since it's just a practice amp really.



Oh, and obligatory pic.


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looks like you bought yourself a Version 1.

You have to be careful as most of the mods are V1 or V3 and some things are different.

Like the heaters if I recall. And some differences like R1 is 68K instead of 1M.

and I think some caps..?


never did a V1.


one thing for sure. the voltages are a mess.. you're beating up your tubes. the voicing is funky and it's overall not the best of the versions.

Hope you got a deal.

There's a faq here isn't there? probably start there.

duhvoodomans stuff is good but I haven't been there a while so I don't remember which version he dealt with.


still a lot of potential so don't be discouraged. Just read your safety info over and over and over!


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His is a V1 I think, originally had the 68K R1 value, which he switched to 1M, among other things. So that helps. This scematic that he links to on his site appears to be for a V1 too.



So there seems to be plenty of info on V1 mods. Will probably look into the transformer mod too, and possibly a speaker change later on down the line. lots of local amp building folk who can probably help out with parts there.

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i've had some interesting v1's.. your combo appears to have the big logo which is whack for an old one..but anyway.. some v1s have v2 boards..the output board where the 4ohm speaker socket is should have 2 blank spots either side for mounting stereo sockets..so then you just need to drill the chassis and rewire the board a little.. i have mine setup with 1st socket is speaker (with switch above to select ohms), 2nd socket is headphone and 3rd is line-out..


anyway you should open it up and check it out!!..pop the 4 plastic things on top and remove the chassis (after removing the back, or during :-)..then you'll have a better idea of what you'll need to do..post pics of the inside if possible :-

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Ok fellas, I started to modify it today. I was planning on following Duhvoodoomans page pretty much all the way, but it seems that my VJ is a little different.


Here's a pic.


Excuse the enorminty of it, but it needs to be big so you can see


This is Duhvoodooman's



As you can see, his has 3 large filter caps, while mine has 4, and a 5th one, that I'm not sure what it's for. I'm guessing mine is a V2 board. I have installed new resistors in R1 and R2 as per duhvoodooman's page. And I've also installed the bridge rectifier and capacitor on that, ensuring it's installed the right way of course, and connected the orange wires to their appropriate places. What I need to know is which terminals on the rectifier will I connect to T5 and T6. I can't see that one Duhvoodooman's page.




Also, if you look at his page, he wired a large 100uf 450V capacitor in parallel with the small filter caps on the board. Can I still do this to mine? Is there any need to do this to mine? Where will I connect it if so? I'm guessing it's no different, I just have an extra cap, so I could wire it to the right most one in my picture, and it would work the same, correct?


You'll also see he fitted a 60pf ceramic capacitor to the empty C3, or at least to one of the terminals, then to a switch, which he later changed for a 100pf one for more brightness. I opted for the 100pf one outright, and was going to wire it into both terminals of C3, so it is on permanently, not connected to a switch. Of course, mine is different, and I don't seem to have a C3, let alone an empty one. Again, can and do I still need to fit this cap, and if so, where do I put it?


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No sweat! You have a version 2 VJr, so you don't need to worry about the extra filter cap, or the version 1's heater mods.


Except for the bias mod, which outlines good biasing procedure for any SE cathode biased amp, just concentrate on mods specific to the v2/v3 VJr's.


Here's the VJr bias info.



Plenty of great mods listed here. http://www.sewatt.com/node/16248



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So I don't need the bridge rectifier to convert the tube voltage to DC? Is it already DC?


Well this is a shame, because I like the mods that Duhvoodooman did, now I have to figure out what I can do to achieve the same sort of result for a V2 amp.

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C12 is next to the bridge recitifer for the heaters on your board.. hence you have 2 now.


its not a shame - your amp was already closer to duhvoodoomans..


you do undertand a V2 is better than V1 (hence why duhvoodooman had to do mods to get his V1 to be more like a V2 which you already have). and a V3 is slightly more improved again, although I'd prefer to have your V2..it's better for modding :-

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Yep.. it's a V2.

Looked like a V1 in the pic, to me!

But you should have known immediately by looking at the board.. it's pretty obviously different than the V1 on duhvoodoos site.

I'm sorry if I misled you, I really didn't mean I KNEW you had one..

Still you haven't hurt anything.


look at this:


Those changes you see from stock are pretty much what everyone does.. with some additions and tweaks to personal choice.


And yeah. you've done the right thing coming in with quesitons.. saved yourself doing something twice!

C3/4 at 1uF 35V electrolytic radial leads..

C1/2 .022 sprague orange drop, or mallory, or sozo. but for the stock board.. I'd got with sprague as the leads are easier to get in there.


By the way... when you put in any components.. look at the size of the leads. often they are bigger..

so shine 'em up with a file around the area that's gonna push through. for good contact.

and put a bit of a point on them so they don't push the solder pad off when they go through.. and don't make them longer than they need to be.. just enough to get through the board.


Your main objective is gonna be to get the voltages corrected.. then get to the mods for tone and performance.


And that's what you'll probably be following overall.


and read that link gil put up!


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