in need of some quick guidance (noob to tube amps)

Mike D

Mike D

New member
Hey guys. Just got my Jubilee back from the shop to have it serviced. Mine is a 2x12 combo with 2 16 ohm speakers. The first question I have is shouldn't the impedence switch be set to 8 ohms and not 4 ohms? It was set on 4 when it left the shop today. The second question is a complete newbie question, so I apologize ahead of time. What should the mains voltage selector be set on? 120, 220, or 240? Right now it is on 120. I live in the U.S. (New Jersey) and the electricity is fairly new. Thanks for your help guys.
 
Re: in need of some quick guidance (noob to tube amps)

If you've got two 16 ohm speakers the amp should be set at 8ohms...if they're wired in parallel, they probably are......If you're living in the USA you want the voltage set to 120.....


*Info corrected*
 
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Re: in need of some quick guidance (noob to tube amps)

metlking said:
If you've got two 16 ohm speakers the amp should be set at 8ohms...if they're wired in series, they probably are......If you're living in the USA you want the voltage set to 120.....
Click to expand...

2 16 ohm speakers in series would be 32 ohms. They are likely wired parallel. That would be 8 ohm.
Maybe the shop was cranking it through a 4x12 while they had it....
 
Re: in need of some quick guidance (noob to tube amps)

OK, that's what I thought... I figured it was supposed to be set on 8 ohms. I played it unknowingly set at 4 and I think it sounded a little off... I don't know, weak? Would this happen if was set at 4 ohms instead of 8? Also, the switch consists of something that looks like a slit, are you supposed to use something it particular to adjust it?
 
Re: in need of some quick guidance (noob to tube amps)

Yes it should be set to 8 ohms. Use a coin or screw driver to turn it. There might be some slight tonal difference changing from 4 to 8 ohms.

Mains voltage should be set to 120. When you get famous and tour Europe, those other settings will come in handy.

Welcome to the wonderful world of tube amps. Marshall combos are one of the coolest but most overlooked types of amps out there.
 
Re: in need of some quick guidance (noob to tube amps)

Reload in 5 said:
2 16 ohm speakers in series would be 32 ohms. They are likely wired parallel. That would be 8 ohm.
Maybe the shop was cranking it through a 4x12 while they had it....
Click to expand...

Yes, thats what I meant! The Bud Lights of last night where confusing things a bit........:nervous:

Info corrected in my original post-Thanks!
 
Re: in need of some quick guidance (noob to tube amps)

One more question guys... is there a certain smell that is common when running a tube amp? I'm not sure I'd call it like a burning smell, but it is giving off some smell. Is this just the heat or is it something I should be concerned about? I just had it serviced, I'd be pissed if I had to send it back!
 
Re: in need of some quick guidance (noob to tube amps)

I use a guitar pick to adjust the impedance selector on mine. I also notice a 'warm' smell when I've been playing through it for a while; I wouldn't worry as long as it sounds ok and you don't see smoke. The power tubes are extremely hot when operating, so this doesn't sound unreasonable.
 
Re: in need of some quick guidance (noob to tube amps)

Yeah, no smoke, just a certain smell. I'm assuming this is normal. Sorry to be asking so many questions but I'm so new to tube amps and just want to make sure I'm doing things right. Btw, the background noise or whatever you want to call it that you hear at higher gain/volume settings... can I remedy any of that with a noise suppressor/gate? I'm not using any pedals right now, but will. If the problem is noise from preamp gain, would a gate/suppressor in the FX loop help any?
 
Re: in need of some quick guidance (noob to tube amps)

If you use a lot of preamp gain, any tube amp will hiss. Mine certainly does and I used to run a HUSH in the effects loop to deal with it. After a while I got sick of the HUSH choking off sustain when I didn't want it to, so I sold it. These days I'm happy that my amp doesn't hiss a loud as a Recto and I deal with the hiss.

One thing you can try is to turn the volume on your guitar all the way down. If the noise continues, it's probably preamp tube hiss. If you're hearing a hum that stops when you turn down the guitar, you need to look at how your guitar is grounded.
 
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