Adding a Speaker Cabinet to a Valve Jr COMBO

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Buck62

Buck62

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I have an Epiphone Valve Jr combo with the 8" stock speaker. I swapped the stock Sovtek tubes with a TungSol 12AX7 and a JJ EL84 and it sounds great, with better punch and more of a sweet, musical chime to it. The only thing lacking now is that I'd like a little more low end, like you get with a 12" speaker. I was thinking that swapping out the stock speaker to a better one, like a Weber, might help, but not provide the beefier low end I'm looking for, to record with.

The stock speaker is a 4-ohm speaker. I don't want to get rediculous with spending a bunch of $$... I just want something pretty good that does the job pretty well without breaking the bank. A brand new cabinet is out of the question, because they cost too much. From what I've read, newer VJ combos like mine also have an extra wire or two so the output can be converted to 8 ohms. Is this a simple conversion?

Maybe you guys can give me some ideas on the best options here.
 
No ideas here?

Can I use an 8-ohm speaker box without doing any conversion work?

Hello? :confused:
 
Yes, you can use an 8 ohm speaker with the 4 ohm output. However, it will approximately half the power output of the amp. I can explain the theory, but someone else here would be better in the actual mechanics of wiring an output to the leads (i.e. if you need another resistor in line, how to permanently add an output jack and use either speaker, etc.)

Site sure is slow today, took me about 8 minutes to post this from the time I hit reply... I bet more people would respond if they could easily get through.

Pete
 
Do you want to build your own cabinet or just swap speakers in the VJ cab?

If you build your own, you can use 2 8ohm speakers (8's, 10's or 12's) in parallel in the cab to get the 4 ohm impedance.

If you swap the speaker in the cab, you can use one 8 ohm which as mentioned above will cut the output power in half, and probably change the tone/distortion as the amp won't be working as hard, or, you can replace it with a better 8" 4 ohm speaker.

I don't know anything about "extra wires" as I've never seen the combo. A schematic would help.
 
that little epi cab sounds decent for the money and will definitely give you a fatter sound than the 8" internal speaker. the valve junior combo is wired for both a 4 ohm or 8 ohm load. the 4 ohm tap will probably work fine with an 8 ohm speaker.

*read up on basic tube amp safety before even thinking about opening your amp up!*

iif you want to use the 8 ohm tap, it's capped off from the factory inside the amp. it's the red wire from the output transformer. the brown wire is the 4 ohm tap and the black is the common. there's not much to figure out there. red and black for 8 ohm or brown and black for 4 ohm. you could install or have someone install a switch to flip between 4 ohm and 8 ohm so that you can use the internal speaker, an external speaker, or both at the same time.

the epi single 12" cab is about $130 and adding the switching capability should be less than $10 in hardware. cheap enough for ya? a super cheap alternative to the epi cab would be to build a butt joint cube from salvaged plywood and drop a used speaker in it. an uncovered plywood cab wouldn't be pretty, but depending on the speaker could sound much better than the epi cab. your ears, your money, etc. good luck.
 
TravisinFlorida said:
you could install or have someone install a switch to flip between 4 ohm and 8 ohm so that you can use the internal speaker, an external speaker, or both at the same time.
Click to expand...

That's a great idea!

Pete
 
TravisinFlorida said:
yes, if wired parallel. if wired in series, 12 ohms. using the 8 ohm tap that shouldn't be a problem.
Click to expand...
True, but what's the point? By increasing the impedance by a factor of 3/2, you'd only get 2/3 the power output of the amp total between the two speakers. Also, it would be harder if not impossible to overdrive the amp for a distorted sound.

Edit:
Now that I think a little more :), I am assuming a constant voltage across the output, which may not be the case. Actually, I don't think I'd use more than one output terminal at a time, or connect them together, without knowing how the transformer secondaries were wound.
 
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TravisinFlorida said:
that little epi cab sounds decent for the money and will definitely give you a fatter sound than the 8" internal speaker. the valve junior combo is wired for both a 4 ohm or 8 ohm load. the 4 ohm tap will probably work fine with an 8 ohm speaker.

*read up on basic tube amp safety before even thinking about opening your amp up!*

iif you want to use the 8 ohm tap, it's capped off from the factory inside the amp. it's the red wire from the output transformer. the brown wire is the 4 ohm tap and the black is the common. there's not much to figure out there. red and black for 8 ohm or brown and black for 4 ohm. you could install or have someone install a switch to flip between 4 ohm and 8 ohm so that you can use the internal speaker, an external speaker, or both at the same time.

the epi single 12" cab is about $130 and adding the switching capability should be less than $10 in hardware. cheap enough for ya? a super cheap alternative to the epi cab would be to build a butt joint cube from salvaged plywood and drop a used speaker in it. an uncovered plywood cab wouldn't be pretty, but depending on the speaker could sound much better than the epi cab. your ears, your money, etc. good luck.
Click to expand...

Hey, thanx... I'll probably try doing the switch thing between the two outputs. Having the option of using the original speaker or a larger 12" speaker would be great. It should give me the fatter bottom end I'm looking for.

On a side note, I plugged my Digitech RP200A into this little combo and I was able to nail a dead-on Fender Twin tone as well as some very realistic boutique amp tones.

This little combo is the best $140 I ever spent on guitar-related gear. :)
 
Buck62 said:
Hey, thanx... I'll probably try doing the switch thing between the two outputs. Having the option of using the original speaker or a larger 12" speaker would be great. It should give me the fatter bottom end I'm looking for.
Click to expand...
You could use a jack like this to save the cost of a switch. When the cable to an external speaker is not plugged in, the original speaker is connected. When you plug in an external speaker, it disconnects the combo speaker and connects the external one.
 
Just for your info, as far as I can see, the little Epi cab (Which has gotten good reviews) is 16 ohm.
Not sure why they would have chosen 16 ohms but that's the only value I see listed at MF.

Buck, I actually do about a third of my gigs with the Valve Jr. head into a single 12. I use a Rocktron Utopia modeler in front of it which takes care of the lack of tone control. I guess that's what you're doing with the Digitech.
It gets strained at louder volumes but fro small clubs it does great. I'm thinking about getting a second one and modding the crap out of it.
For the money every guitarist should run out and get one.
 
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