Epiphone Valve Junior Head for Sale

true, but internets are in infinite supply, so we can always award more if we need to.

 

About the dummy load thing, besides improving sustain does it change your tone in a bad way? Apparently there is a tone difference between dummy loads and speaker simulating loads like the Weber Mass...

 

here's the final word on purely resistive dummy loads - they sound really, really, REALLY ****ing nasty if you aren't running the signal though a compensation circuit of some sort afterwards. i built a dummy load + line out into an amp i made for someone because he insisted on having a line out of some sort after the OT. it was horrendous. changed resistor values on the tap in order to drop line out impedance, but that didn't help at all either. only when i plugged the speaker in did things improve somewhat, and it was tolerable after i ran the signal into impulses.

the other downer - it was noisy as hell because you don't have the high-frequency roll off happening around 5kHz like a real speaker does.

the weber MASS attenuators are supposely a lot better than resistive loads, but i've heard read mixed reviews of those too. the best attenuator/dummy load/line out i've personally heard to date is the SPL transducer, but that comes with a hefty price tag.

i'll just stick to power scaling+miced cab.

 

^thats what emulated outs are for
plug a the load into the cab out
plug the headphones in the emulated out and..play
i ordered 6 16ohms resistors rated at 10w yesterday
this is going to be my first diy
wish me luck...
btw flood i havent soldered things before do you suggest making the dummy on a breadboard
and will i need heatsinks along with it?

 

i still maintain that they sound pretty shite. anyway, what schematic are you using and what amp are you planning to run into the load? you have to be careful with these things. e.g. the dummy load needs to be rated for a bare minimum of twice the wattage of the amp you are planning to push into it. some amps can't handle being run full-tilt into a resistive load, so be careful or you will smoke your output transformer. how do you plan to build and house the load, and what final impedance are you aiming for?

 

Home-Made Dummy Load Tutorial - Save Money!!! - Ultimate Metal Forum
i plan to use this schematic basically you wire all the resistors in series to make one
i'l be using it with a 6505 head which has variable resistance i am aiming for 16 ohms
and i was thinking to mount them on a breadboard but i am confused the heat generated can melt the breadboard so...
also look into this
Tube-Town GmbH - Hot Stuff Cool Sounds

 

ok, stop EVERYTHING you're doing and toss your resistors, really. good thing you asked your questions beforehand. this is why a little knowledge is a dangerous thing. i would not go to ultimate metal for any DIY - there's tons of forums there dedicated to DIY and amp building with people who are a lot more knowledgeable.

wiring all your resistors in series to make one, in your case, will give you a 96 ohm resistor. if you meant parallel, you will get 2.6 ohms. in both cases with a power handling of max 60W. both of these would have you looking for a valve junior pretty quick.

a. wiring your resistors in series would present a load of about 100 ohms to your secondary, and thus a value of around 11.8 kOhm on your primary. your amp will, quite literally, breathe fire.

b. the amp would take a 2.6 ohm load connected to the 4 ohm tap quite well, but not 8 or 16 ohms. there's another problem though - that max 60W capacity. since most WW/cement covered power resistors are the fusing variety - open circuit when blown. open circuit at the speaker = see a.

the only post that even comes close to being relevant to your needs is this: Ultimate Metal Forum - View Single Post - Home-Made Dummy Load Tutorial - Save Money!!! - the picture more than the post. that is the way you should be building your dummy load, and no other.


if you plan to connect it to the 8 ohm output, your target dummy load is thus rated at: about 6.5 ohms and 240W. you can get this by using 6x 20 ohm resistors rated at 50W each, at best of the type shown in that pic, connected in the following way:

// = parallel; + = series

(20//20)//(20//20)+(20//20)

use a decent gauge SPEAKER wire to make all connections and you will have a dummy load at 6.7 ohms and 300W. heatsink that to a metal plate and you should be fine with pretty much any 120W amp with an 8 ohm speaker out.

if you do not know how to connect the resistors in parallel and series then i would seriously advise you to buy a commercially available attenuator or dummy load and not risk your amp.

 

N00b question - how did the power rating change based on the ohmage? You mentioned 60W on the 4ohm output and 240W on the 8ohm. Is there a formula? I know I can look it up but meh.

 

it doesn't at all; maybe my explanation was a bit muddled, let me reiterate:

deepsal HAS ordered 6x 16 ohm resistors rated at 10W each. this gives him either 96 (series) or 2.6 ohms (parallel) in total, but in both cases the maximum power is 6x 10W = 60W.

deepsal NEEDS an equivalent resistor (resistance dependent on what speaker impedance he uses) of rated at a minimum of twice the power of his amp. the 5150/6505 runs 4x 6L6GC at between 450V and 485V on the plates and is rated at 120W. hence, he needs 2x 120W = 240W. 300W won't hurt.

 

Oh you meant that the resistors, being able to handle a max of only 60W, would fry and create an open circuit since the amp can run up to around twice that much. Got it.