Epiphone Valve Jr, What are they good for?

[TIMBO]

Hi guys, Haven't had much to do with them and i am able to pickup one for a good price. Plays well and is in good condition. Thanks

[toomanyslurpees]

I picked one up and tweaked for the sake of tweaking, Watts tube audio sells turret boards for them, I threw one in and the total was still under $200. Amp sounds good, it has no clean, it's fun and cheap.

[ampgeek]

I have seen a lot of folks turning those into Marshall'esque 18 watters (1974X IIRC).  Many use the term Baby Will conversion.  Lots of demos on Youtube indicate it to be a real screamin monster!  Looks like a ~$180 conversion including new OT.  I have a parts list around somewhere for that and will post it up if I can find it.

Cheers,
Dave O.

[ampgeek]

Here is a link to the Baby Will conversion low down.
Looks pretty cool!
Have fun,
Dave O.

http://guitaramplifierpcbs.com/liteiib.aspx

[bigdaddy]

Honestly all they really need is a tone stack to be minimum usable pratice amp IMO. With only a volume control you just cannot control much of anything. There is enough room in there to turn it into an 18 watter or a KT88 champ if you like. Just make sure the trannys fit in before you permanently mount it.

Watts does sell nice conversion boards that fit right in. Use better parts and add a bass and treble control. That way now you have a pretty good sounding 5 watt head. Or just use the stock amp but put some switches in there to control the bass and treble.

You can do a lot of things with it. Mine is now a firefly. Not an original part left in it. When I plugged it in the sound was so bad I tore it apart almost immediately. The Blackheart is a lot better sounding from the factory. All it is basically is a Valve Jr. with a tone stack, same guy designed them both from what I understand. I don't think the stock PT can be used for anything more then what it is, maybe you can add another EL84 in parallel but that's would be it.

Just thought I'd add this in case you were thinking about doing the whole Plexi thing to it, which IMO doesn't sound anything like a Plexi. I'll say it a million times a single 12AX7 set up right has all the gain you need even with a TS. If you want to go into real overdrive territory use a pedal. Adding extra gain stages really just turns these low wattage amps into into buzz saws, although some people like that sound, or it is their sound. If you want to go higher gain use an EF86 or 5879 with either 1/2 of the 12A whatever or both triodes in parallel, I used a 6AV6 also. Now you have a truly higher gain preamp without the buzz saw.

[tonewood]

BigDaddy-

When you say-

"If you want to go higher gain use an EF86 or 5879 with either 1/2 of the 12A whatever or both triodes in parallel"-

are you talking about adding the pentode for the input or a second stage?
also, will the existing PT handle the extra tube or would I need a bigger PT?

Thanks

[TIMBO]

Thanks guys,I already have two small amps ( champ and stinger)both have their own sound, i think the Jr sounds similar. If i was the do a full rebuild i think i would try for something different( its a combo). Looking through the countless schems to see what might fit (board size, existing holes, trany size etc.) I was thinking maybe the High Octane might fit.I've heard good and bad about this amp, any comments. Thanks

[Geezer]

Here's a great project for a VJr>>>>

http://www.el34world.com/Forum/index.php?topic=3156.msg25903#msg25903

The "original" (1st schem on the thread) is the best one.
I recently had the amp back in for some servicing/tweaking a few days ago & it really is a great sounding amp. (the owner plays a stock tele & wanted a bit more Paisley-type overdrive, so I upped the V1A Rp to 220k....did the trick)

HTH, Geezer

BTW, the original/stock PT on the VJr can easily handle 2xEL84's & several 12A_7's. The several I've done don't even get warm.

[Geezer]

BigDaddy-

When you say-

"If you want to go higher gain use an EF86 or 5879 with either 1/2 of the 12A whatever or both triodes in parallel"-

are you talking about adding the pentode for the input or a second stage?
also, will the existing PT handle the extra tube or would I need a bigger PT?

Thanks

Here's a circuit I added a 5879 to (in a gutted VJr chassis)>>>

http://www.el34world.com/Forum/index.php?topic=3156.msg74828#msg74828

It's a total rebuild, but might give you some ideas on how to add a pentode into an existing circuit.

G

[TIMBO]

Sounds great  :grin:Got all the necessary parts.Will it all fit in the combo and will the OT/speaker handle the extra power. Thanks

[bigdaddy]

On SE amps I prefer to use the pentode as a driver. It's much easier to set the circuit up that way. You're really not asking a lot of gain from the pentode it just provides naturally more gain and high end gain that a 12A whatever just cannot provide. So I used them to drive the power tube.

You can do whatever you want in terms of tone stacks or whatever with the pentode driver, no worry about insertion lose and like I said you get that high end Marshall or Brit sound a 12AX7 just cannot provide in this type of amp. I have tried so many combinations and soncially the closest thing to a true Plexi was a triode from the 12AX7 or 12AY7 into a TS into an EF86. Setting the EF86 for less then maximum gain made the problematic EF86 not an issue. In other words no microphonic issues.

Another bad design is the TS before the power tube on SE amps. Many disagree but it's just my observations from countless designs and modification to those designs. I even used dual pentodes and had a dual EF86 driving an EL34 for an awesome sound. It did that Brit thing well, Hi-Watt, Orange, Vox, Marshall.....whatever. It had a lot of tonal flexibility by adjusting the gain and tone of each tube. I even used a dual 6SJ7 that kicked. A really cool SE amp I built was 1/2 a 6SL7-TS-6SJ7-6L6GC.

Many different combinations of preamp and power tubes in SE operation.

[6G6]

I think a few have been used as harp amps.
Mod to get whatever level of OD you want,
then mike into PA.

[TIMBO]

Thanks for the feedback they all sound great :smiley:I didn't want to get into an involved build but thanks anyway. The amp itself sounds great ( new 12AX7EH and mullard EL84) and not a buzz to be heard. Surfing the net and came up with the HOT ROD version of the VJ and to my surprise the PCB had extra components that the standard VJ did not have ( DC filaments,220k bleed,220r in the filter stage,extra 22uf/450v cap). So i thought of using the PBC ,and adding the extra bits would be the way to go.I found a demo of the hot rod and was surprised to find that not only did it have a reverb but you could use it as a reverb pedel, GREAT!!!There so many MODS for this amp i'll start with the schem (copy of the Gibson schem) and see what you guys think. Thanks

[TIMBO]

Hi guys, Made the necessary changes but waiting on the 100uf+100uf cap can to arrive. I've also updated the schem and finished the faceplate.There seems to be an endless amount of mods for this one so feel free to add to the pile.I'm also thinking of adding another 200uf to the EL84 cathode after i have had a listen to it. I've not been able to find a manual for this amp so i was hoping that someone could explain how the LINEOUT works or could i be able to work it so as to be able to plug it into a FX loop.Thanks

[TIMBO]

A couple of pics.

[DummyLoad]

they seem to be the most popular donor chassis on the planet right now... would that be an accurate assessment? 

i've come close to buying one just to join in on the fun - problem is, every time one comes up on craigslist in the area for a price i'm willing to pay,  i'm too slow on the draw! 
  

[TIMBO]

I've got to admit this mod was the result of a impulsive buy. We have a place called CashConverters (second hand shop) that has the general stuff and its rare if they have any valve amps. So when i found it i had to buy it, just because the parts alone would cost more.I'm thinking if it is a success i might convert it to a turret board Thanks

[jeff]

I turned mine inot a nice post speaker reverb unit ala valco. Problem was I have the head and mounting the tank in the head picked up a lot of transformer hum.

 Anyone know what the current ratings on the transformer are? Seems cool but that transformer was meant to run 1 EL84. Can it take the extra draw of two push pull?

260v@?mA
6.6v@?mA
12V@?mA

[TIMBO]

Hi Jeff, I've got the JV up and running but i don't have a clue to answer your question.Some direction maybe.As said VJ is up and running and sounds MAGIC   Quiet, lots of grunt and very bluzy. The reverb is good (short tank) so i don't know if i can expect much more.In one of Geeza's post on a VJ he talked about adding more filtering to the standard 22uf of the EL84 cathode but i don't think it added anything. Overall a great little amp. Valve Data posted. Thanks

[Geezer]

Anyone know what the current ratings on the transformer are? Seems cool but that transformer was meant to run 1 EL84. Can it take the extra draw of two push pull?

260v@?mA
6.6v@?mA
12V@?mA

The un-used 12v is a clue........Epi used that same PT on several other amps, all of them larger in power output than the VJr (cost saving measure.....buy LOTS of 1x PT rather than a separate PT for each model). The 12v is used to run the DSP effects on some of them.

I have run 2xEL84's + 3x12AX7's on several builds & the PT doesn't even get warm.

G

[jojokeo]

Timbo, what is the "reverb out"? Is that supposed to be a "line out" instead?

[TIMBO]

Hi jojokeo , I'm glad you asked.I think that it is a LINEOUT but i haven't had a conformation from anyone that it is. I did read that the unit can be used as a stand alone reverb but have not found a user manual to how it is used. For the moment i have wired it to a stereo jack.So if there is some more info out there i would be interested. I did have a thought of putting a FX send , return either side of the 3M resistor to be able to connect it to other amps. Any thoughts, Thanks

[jojokeo]

It appears to me that the 'fixed' line out is correct going to the lowest/supposedly tip part of the jack and w/ a switching jack the OT is protected from no speaker being plugged in and/or also serving to be used w/out a speaker for quiet recording.

The lowered signal point btwn the 10M&100k can be also taken to a 'send' jack & returning the signal before the vol pot there. You could ignore the two resitors and instead run the full signal w/ a vol pot before the 'send jack'  that gets switched in when plugged in giving the output vol control to your send pedals or into another amp's power section (return/power-in).

[TIMBO]

Thanks jojokeo, I think i understand the part of the jack grounds the speaker out, but you might have to draw me a picture for the other part. Thanks

[jojokeo]

I haven't much experience w/ Jschem but thanks to this it's forcing me to try a bit more on it. Here's what I have done in the past if I wanted the send/return and variable lineout options.
HTH, Joe

[TIMBO]

Thanks Joe, You did a great job. Thanks for confirming what you were saying.

[jojokeo]

Thanks timbo, I think I can work w/ the program a bit better now since I found & printed some info basics. I wish there was an "edit > undo" ability w/ the program but things are easily deleted and fixable. Do you know how to copy & paste a section from another saved schematic/file? I had no luck w/ numerous tries. Or is there a tutorial/help thread you can point me to?

[TIMBO]

Jojokeo, there is a new program on the startup page i think it is a lot better.The more you use it the easier it is to use. I use the other program PC Express and found it ok. Stick with it.