Using a tech21 power engine to power a valve junior.

  • Thread starter Thread starter projekt_420
  • Start date Start date
P

projekt_420

New member
I just bought an Epiphone valve junior head. I just love the way it sounds. The low wattage however will make it hard to battle with a whole band in a live situation. I was thinking about using a powered cabinet like the power engine 60 by tech 21 as a speaker instead of the passive cabinet it comes with. I know thats not really the most "regular" of setups, but i tried the VJ into the slave input of a behringer 60 watter and it was loud! And boy did it sound sweet. I just want to know what i should look out for in order for my gear not to explode.
Thanks,
Christ
 
projekt_420 said:
I just bought an Epiphone valve junior head. I just love the way it sounds. The low wattage however will make it hard to battle with a whole band in a live situation. I was thinking about using a powered cabinet like the power engine 60 by tech 21 as a speaker instead of the passive cabinet it comes with. I know thats not really the most "regular" of setups, but i tried the VJ into the slave input of a behringer 60 watter and it was loud! And boy did it sound sweet. I just want to know what i should look out for in order for my gear not to explode.
Thanks,
Christ
Click to expand...

FireExtinguisher.gif


Never run the output of one amp into the input of another. Also never run a tube amp without a proper speaker load because it's very hard to get that little puff of smoke back inside the transformer.
 
ok, you should really read the manual of the Power Engine...

i really can't understand how you got it to work. the way i understand PE - it has a "line-level" input, which gets amplified by PE's transparent power amp and fed into PE speaker. I am no electronics buff, but I don't "get" how that setup wouldn't fry the amp (and even sound sweet).

maybe PE has a "speaker in", which bypasses the power amp and lets your Epi VJ drive the PE spaker cab? That seems more consistent with your results.
 
I ran the output of the VJ into the slave input of the Behringer. It worked. Seing as the PE is all slave i thought maybe it would work. Would it? Or will that dude with the crazy picture be right?
 
the 'slave input' on the PE is a line level input. the outputs on the VJ are speaker outputs which are a multitude of the power of a line out.

the input on the PE will get immensely overloaded AND won't be able to provide sufficient load for the tube amp.

you will destroy both the VJ and the PE.


make sure to post some pics!


edit what you need is an extension cab.
 
Last edited:
but he already said that it both worked and sounded great.

i've never seen a connector on an amp marked "slave". they're either Line In, Line Out, Speaker In, Speaker Out, etc. (I'm nost saying that I've seen it all).

what does it say on the input and what does it say in the manual?

:o
 
Gear_Junky said:
but he already said that it both worked and sounded great.

i've never seen a connector on an amp marked "slave". they're either Line In, Line Out, Speaker In, Speaker Out, etc. (I'm nost saying that I've seen it all).

what does it say on the input and what does it say in the manual?

:o
Click to expand...
I've seen plenty of line inputs marked 'slave'. It's not so common now but it used to be. It generally was used to describe a powered speaker that could be run off a line signal from another amp.
And the reason it worked is that line levels can be as much as a couple of volts and even more. Hell, some things can put out even 10 volts as a line level so line inputs often can deal with fairly wide voltage ranges. Since the Valve Jr. is a 5 watt amp ..... voltage-wise, it's only putting a few volts into the input. It's quite possible that it may not hurt the slave speaker.

But it's absolutely a bad idea for the amp because tube amps are very sensitive to what load they're running into. That VJr is rated fro from 4 to 16 ohms. The input load of that slave is gonna be somewhere in the thousands or tens of thousands ...... NOT an acceptable load for that amp.
Anything is possible but I suspect that the amp'll die at some point ...... not so sure about the slave.
 
great explanation Lt. Bob, thanks! I hope it gets read on time by projekt_4 before it's too late :D
 
projekt_420 said:
thanks guys. so attenuator huh? that will work for sure?
Click to expand...

You don't necessarily need an attenuator, per se. What you need is a simple dummy load for the VJ, and simple voltage divider to give a nice line out.
The dummy load is easy - just use a big resistor that has the same value as whatever speaker it wants. I'd use one of the 8 ohm 20 watt non-inductive power resistors they sell at Radio Shack - they're cheap, they can take the full power of the VJ no problem, and they're made specifically for crossover networks, so amps don't mind them. For the voltage divider, you could just have a simple potentiometer - say, 10K to 100K linear or audio taper, wired up like how you'd usually wire a volume control. Use that to set a nice level so that the input of the slave amp doesn't distort and you're good!
I've done simple slave setups like this for my friends and they've had good luck with it. We slaved a Traynor YBA-1 into a big solid state power amp and almost shook my house apart. We didn't use a dummy load in that setup because he wanted to still use the Traynor into a cab onstage and have the slave amp for adding more cabs/power... but the principle is the same no matter what setup you do.
 
I think that requires a lot more soldering and technical know how than i'm capable of. Is there anything i can just bolt on?
 
Cool guys, appreciate the help. One last question... what does the ohm ratings mean anyway? I decided to forgo the Power Engine Idea for now and just get a proper cab from avatar. I was thinking a 1x12. Could you guys please give me suggestions on what speakers to get and at what impedance. Im looking for VOLUME, clarity and vintage character i suppose.
 
Also, what does the micromass attenuator really do? Would i be able to use both the line out and amp out at the same time? What do the knobs do?
 
projekt_420 said:
Cool guys, appreciate the help. One last question... what does the ohm ratings mean anyway? I decided to forgo the Power Engine Idea for now and just get a proper cab from avatar. I was thinking a 1x12. Could you guys please give me suggestions on what speakers to get and at what impedance. Im looking for VOLUME, clarity and vintage character i suppose.
Click to expand...
Well ....... for volume you're gonna want a speaker with a high sensitivity.
Guitar speakers can range from say around 97db to as high as 103db sensitivity. That's usually measured at 1k ...... 1 watt.
So the higher that number .... the louder the speaker will be IF that same standard is used to measure that characteristic so be sure to check how it's measured.
You can go to Emminence's website and they have response curves and specs on all their speakers so it's a good place to start to get a handle on what speakers do and figure out what you might need.
 
projekt_420 said:
Also, what does the micromass attenuator really do? Would i be able to use both the line out and amp out at the same time? What do the knobs do?
Click to expand...

An attenuator allows you to crank the amp for tube saturation while maitaining a low volume. Basically it acts as a secondary master volume that will not affect tone. Weber adds EQ into some of their attenuators, but I don't think the micro mass has any. Yes you can use the line out and speaker out at the same time. Just make sure to have the attenuator full on if you plan on going line out only, so it acts as a dummy load.
 
You must log in or register to reply here.
Back
Top