Electronics engineer

[luap]

I want to disconnect the speaker on my amplifier and run the speaker output into a speaker soak DI box, "a millennia td-1 to be precise"."The reason why I don't want a speaker connected to my amplifier is because my family's complaining about the noise I make".Now I want to put a 6 ohm resistor"which is the ohms of the speaker" between the +/- speaker wire to simulate a loaded speaker. My question is, is this the right way to do it and if so what voltage resistor or type should I use?
Thank You.

[grahluk]

Originally posted by luap
I want to disconnect the speaker on my amplifier and run the speaker output into a speaker soak DI box, "a millennia td-1 to be precise"."The reason why I don't want a speaker connected to my amplifier is because my family's complaining about the noise I make".Now I want to put a 6 ohm resistor"which is the ohms of the speaker" between the +/- speaker wire to simulate a loaded speaker. My question is, is this the right way to do it and if so what voltage resistor or type should I use?
Thank You.

I think I know what you're trying to do but am not clear on how you are getting there or if that will be the best way to do it. Basically you want to load your amp's output "for the sound" but pad it down to a managable volume for practice. Firstly, you must have the correct impedance load on the amp. If your amp's output is rated for 4, 8, or 16 ohms (most common) the total load must match. The td-1 is a great box and does far more than what you are intending but I don't know if that's the ideal solution. The td-1 says it is supposed to be used in parallel with your speaker. If this is the case it's "speaker soak" is probably quite a high impedance so that it doesn't adversly affect what the amp sees as a load. The idea is that the td-1 can accept speaker level signal and turn it into preamp friendly level for recording. Basically a DI for a power amp. Unless I'm wrong it does nothing for volume control of the speaker. It just taps off it in parallel. If you already have the td-1 then your only bet for volume control is to disconnect the speaker entirely. You would then run the output of the td-1 into another audio system (powered monitor, small amp, mixer to headphones, stereo, etc) and use the td-1 for voume control. I would only do this though after finding out for sure if the td-1's "power soak" is sufficient and correct to be the sole load on the amp's output. It should be a reactive load at the correct impedance of the amp. I'm doubting that's the case though by it's use description and size. Previous guitar amp power soaks were made up of banks of high wattage resistors wired to produce the correct impedance desired for the amp. Conventional wisdom had it though that a purely resistive load affected tone at best and caused damage to the amplfiers output transformer because it was a constant load. A speaker being a reactive load (an inductor) changed impedance slightly depending on the frequency of the signal. I say this is conventional wisdom only because I've not seen any hard science on the matter of resistive loads frying output transformers. I have seen plenty of amps though that have been fried by using a power soak. Was it the resistive load or was it just that the thing was run into meltdown because now your ears didn't ring after playing through a power soak for more than a short time with everything at 11? If you really want to make it simple though there are very nice reactive power attenuators for instrument amplfiers. The one that comes to mind is THD's Hotplate. I've used them and known others that have them also and never heard anything bad from it. Each one is basically built to a specific impedance (4, 8, 16 ohm). They have an amp input that completely replaces the speaker as a load. It has a speaker output so that you can then connect the speaker back up but has stepped levels off attenuation to the speaker output. In effect it's like putting a volume knob between your amp and speaker where the td-1 just taps off that connection without breaking it. There are probably some other makes of this sort of load device but that's the one I know of.

[grahluk]

Then again you can always just get a POD and headphones.

[kidtexas]

Weber makes a power soak thingy which is essentially a speaker without the cone. The advantage of this over a resistor or a power soak is that, much like a speaker, the imedance of the thing varies with frequency. I've not heard it myself but had grand intentions of getting one at some point.

http://www.webervst.com/mass.html

[luap]

Thank you grahluk for your response
Yes I do have a td-1 and a pod 2 that I have out grown. I love the excellent sounds of the td-1 but sometimes I need a slight distorted sound that my fender amplifier gives me. Millennia say that the speaker MUST be connected to the amplifier in parallel with it for it to work correctly, and then I go out of the td-1 to my DAW. My problem is, I don’t want to hear the Fender's speaker, so I thought I could disconnect the speaker altogether and put a resistor in its place to simulate a speaker load so to speak, to keep the td-1 happy. I actually did try a 1.5 volt 6 ohm resistor for a couple off seconds and it sounded fantastic, but then the resistor fried, probably due to the low voltage of it. I don’t want to do anymore test's to avoid any damage, so I am hoping somebody here can come up with a good idea to simulate the speaker load.

[luap]

kidtexas
AH, this just may be the solution to my problem.
Thank you very much.

[luap]

Another thought
Why don't I get an old 6 ohm speaker and cut out the paper cone so it wont emit any sound
Would that work?

[ninohernes]

Originally posted by luap
Another thought
Why don't I get an old 6 ohm speaker and cut out the paper cone so it wont emit any sound
Would that work?

The voice coil would not stay centered properly in the gap. The cone stays centered in the gap with the help of the spider, (at the apex of the cone) and the surrounds. Cutting out the cone would eliminate the surrounds, causing the voice coil to tilt back and fourth in the gap, causing rubbing, and it might eveh prohibit the voice coil from moving. Also, the opisite could happen, with no surrounds to hold it back, the voice coil would go flying out of the gap.

[bernieL0max]

a guy i worked for a couple of years ago used electric kettle elements as a load on amplifiers when testing... you might want to try this; a word of caution though, they get hot!

obviously you want to find one with a resistance as close to that of your speakers nominal value... from memory he used several in series or parallel, whatever he needed to get the right value.


other thing is build a sealed enclosure for the speaker, with lots of sound absorbing material... stick a mic (SM57) in there permanently for recording... you get the *real* amp/speaker sound then.

you can run this sort of rig hard (if it's built right) with very little noise eascaping into the room.

[Jay Kahrs]

Originally posted by grahluk
The one that comes to mind is THD's Hotplate. I've used them and known others that have them also and never heard anything bad from it. Each one is basically built to a specific impedance (4, 8, 16 ohm). They have an amp input that completely replaces the speaker as a load. It has a speaker output so that you can then connect the speaker back up but has stepped levels off attenuation to the speaker output. In effect it's like putting a volume knob between your amp and speaker where the td-1 just taps off that connection without breaking it. There are probably some other makes of this sort of load device but that's the one I know of.

Wow.

First of all...any powersoak like the Marshall, THD Hotplate, Dr. Z Airbrake etc. CANNOT be used to terminate an amp. They work as master volume controls and are packed with resistors to turn an amp down. They don't provide a load for the amp. Running an amp into one of these without a speaker attached to it WILL DESTROY your amp. At the very least you'll take out the power tubes and most likely some caps and resistors too. If your lucky the output transformer will be ok, though chances are it won't be.

The only box I know of that will totally take the load off a tube amp and can be used without a cab is the Palmer.

Cutting the paper cone out of a speaker won't work, in a nutshell it's because the speaker will no longer function and will cease to provide a load to the amp. Nino kinda summed up the technical reasons behind it.

Honestly, for silent guitar recording either use the POD or a silent speaker chamber like the Demeter or Randall. There's no easy way out of it. Maybe build out a closet or something with a lotta soundproofing. There's no easy way out of it.

[grahluk]

Luap: I think you are on the right track now. The weber device looks good and is cheaper than the THD unit I mentioned. I knew there were other devices out there since the THD came out. Looks like a good choice.
Jay & everyone: I don't know about all the power soaks out there but I do know about the THD and Marshall ones. Yes stay away from the Marshall. I have known this from first and second hand experience that it will fry your output transformer. If I remember right it uses resistors and a coil (fan motor) as a load. As you play the fan speeds up. A supposed beneficial byproduct is that the unit was self cooling. Not quite. The output connected to the speaker was just a secondary of the load transformer that had multiple taps. As you turned it down it notched the transformer ration down. The THD one I can recommend. I have one that's been in use for about 8 years on a custom built 4x10 Bassman. No problems. I know others that have punished them as well without consequences other than wearing out power tubes at a much faster rate. The load inside them is a small network of coils. While the weber is actually a coneless speaker (magnet and all) the THD looks like a speaker to the amp output. It's just a bunch of wire windings but instead of the electromagnetic movement that happens with a speaker those coils just dissipate heat into heat compound filled channels in the aluminum chassis. I read the weber site. It seems much of their comparison to "other" units pretty much takes aim at the hotplate. I can see why the weber is cheaper/easier to produce. The THD is a rather pretty anodized piece of machined aluminum. That's gotta cost. If I were walking into the situation today I would take a look at both and try them out with my amp. The Weber may be just the ticket. Good luck.

[Jay Kahrs]

Originally posted by grahluk
I don't know about all the power soaks out there but I do know about the THD and Marshall ones. Yes stay away from the Marshall. I have known this from first and second hand experience that it will fry your output transformer. If I remember right it uses resistors and a coil (fan motor) as a load. As you play the fan speeds up. A supposed beneficial byproduct is that the unit was self cooling. Not quite. The output connected to the speaker was just a secondary of the load transformer that had multiple taps. As you turned it down it notched the transformer ration down. The THD one I can recommend. I have one that's been in use for about 8 years on a custom built 4x10 Bassman. No problems. I

I've been using a Marshall Powerbreak on a Vox AC30 for a while with no problems. One of my friends and clients has been using one with a Univox head also with no problems. Guess it's a case of YMMV.

FWIW, I think the Hot Plate sounds a bit better and the light bulb compressor is a cool option to have, but on the flip side it's a fixed ohmage. I needed something that was varible so I opted for the Marshall. I've heard nothing but raves about the Dr. Z which also has different taps on it. Also, Ken Fischer from Trainwreck designed it so it can't suck too badly. thumbsup

[tINY]

Too bad you don't have a twin. You could wire the speakers out of phase with each other and it wouldn't make much sound at all....


-tINY

[Jay Kahrs]

Originally posted by tINY


Too bad you don't have a twin. You could wire the speakers out of phase with each other and it wouldn't make much sound at all....


-tINY

FYI, if anyone tries this at home it may cake your output tranny and make a whole lotta smoke.

[luap]

Thanks everyone for your suggestion,but I have come to the conclusion that nothing beats a real speaker!
So I will take bernieL0max advice and built an enclosure.
Paul

[tINY]

Originally posted by Jay Kahrs
FYI, if anyone tries this at home it may cake your output tranny and make a whole lotta smoke.

Explain how this could be. I'm rather curious....

Both speakers are still hooked up, but moving in oposite directions. Other than sealed cabinets (very few twins are sealed) the load is gonna be exactly the same as if they are wired in-phase. Even with sealed cabinets, the acoustic effects on the impeadance won't be enough to change the loading on the transformer much.



-tINY

[Jay Kahrs]

Well, first of all the theory is kinda out the window. I've wired two 4x12's out of phase with each other powered by the same head and they both move air. If the speakers are in series or a series parallel configuration there's a good chance that the tranny (also depends on how it's tapped) won't like it too much. At best nothing will happen, at worst...a meltdown.

[tINY]

Wiring two 4x12 cabinets out of phase...

First off, the cancellation won't be so good (to much distance between them). Secondly, it the amp can normally drive a pair of 4x12s and you simply switch the two wires going to the second cabinet, but otherwise wire them normally, everything should be fine (except you will loose all your meat at the low end).





-tINY