Power Soak

aron · August 31, 2005, 12:59:54 PM

QuotePurely resistive loads don't present a varying impedance to the amplifier the way a real speaker does. This is supposed to have an adverse effect on sound and possibly on the output transformer. I don't know if I'd bother with a purely resistive load.

Right, that's what everyone says but I know from experience that the results are not always the case. The Trainwrek Air Brake is purely resistive and it sounds as good as reactive loads. Sometimes a pure resistive load can actually make the amp sound more alive. It depends on the type of music and your equipment. All I am saying is don't rule out trying it.

stankyfish · August 31, 2005, 01:06:51 PM

Quote from: aron
Right, that's what everyone says but I know from experience that the results are not always the case. The Trainwrek Air Brake is purely resistive and it sounds as good as reactive loads. Sometimes a pure resistive load can actually make the amp sound more alive. It depends on the type of music and your equipment. All I am saying is don't rule out trying it.

That's good to know -- because the resistive loads are nice simple devices to build. I'd still be a little worried about possible damage to the output transformer; although I don't know what effect, if any, a resistive load would have on it.

aron · August 31, 2005, 01:14:21 PM

I'm also sorry to say that every attenuator is not as good as the real thing cranked so unfortunately that's what we need to deal with right now.

In some cases, the change might be for the better for some people, but the attenuator usually makes the amp less "alive".

stankyfish · August 31, 2005, 01:19:41 PM

Quote from: aronI'm also sorry to say that every attenuator is not as good as the real thing cranked so unfortunately that's what we need to deal with right now.

In some cases, the change might be for the better for some people, but the attenuator usually makes the amp less "alive".

Maybe time spent on building an attenuator would be better spent on an iso box so you can crank the amp and let the magic happen naturally. The iso boxes I've seen seem to be way overpriced compared to what you get.

aron · August 31, 2005, 01:24:12 PM

Good idea. I've never tried an iso box. I wonder if the small cab will adversely affect the tone?

stankyfish · August 31, 2005, 01:38:37 PM

Quote from: aronGood idea. I've never tried an iso box. I wonder if the small cab will adversely affect the tone?

From what I've read, yes. You would need some EQ as the sound that you get from an ISO box can sound a bit tight. I read a great article about this and what bands you need to EQ, but I can't find it...

space_ryerson · August 31, 2005, 04:53:13 PM

I've built my own ISO box, and I like the sound of it. It can be a bit tight, but it cuts through the mix pretty well on recordings. I think the tightness is due to the fact that if the ISO box is truely acoustically dead, then you are only hearing the speaker. It's room ambience that is probably what makes an amp sound 'loose'. When most people record with a regular amp, even if the amp is close-mic'ed, you are still hearing room ambience. Re-amping the recorded guitar parts into a room, and mic'ing the room is one solution that can be implemented.

Dave_B · August 31, 2005, 07:27:39 PM

Quote from: stankyfishI'd still be a little worried about possible damage to the output transformer; although I don't know what effect, if any, a resistive load would have on it.

I have the same concern, but I'm pretty sure it comes from the stuff I've read about Powersoaks. As clever as Tom is, the rumor was that the PS was not real good about impedance matching, and that it could eventually damage an output tranny.

Personally, if Ken at Trainwreck was building them, that's about as good an endorsement as I could ask for.

petemoore · August 31, 2005, 08:25:13 PM

Maybe time spent on building an attenuator would be better spent on an iso box so you can crank the amp and let the magic happen naturally. The iso boxes I've seen seem to be way overpriced compared to what you get.
This is sort of similar to partial blockage of the air, soaking a bunch of power [but not all of it] into a 'thing' like cardboard or...very simple, attenuates the amp, lets the speakers load the amp 'naturally' and lets you still hear some of the amp on stage or whatever...yupp looks funny and is 'untechnical' yet quite effective.

Ed G. · August 31, 2005, 09:06:10 PM

I've got a weber minimass and I find it does its thing best at low to moderate volume levels. If your amp, like my super reverb sounds good at '4' to '5' (not distorting, but punchy and dynamic) but at gigs your anal retentive soundman only lets you turn up to "2" or so, this thing can help. It also gives more control over the volume. I don't use it to get cranked tone at bedroom levels. It sounds too dark and compressed that way. I love mine, I can finally play clean leads without distortion or compression, the amp makes its own compression.

sir_modulus · August 31, 2005, 09:11:42 PM

Let's put this as the general rule...almost all well designed attenuators work well, as long as you don't attenuate too much. If you're looking to make the map quieter and have a speaker cab attached, then by all means go for a resistive load unless you attenuate too much. I personal prefer a Bridged T attenuator for smaller amps, and a special L-pad (of my design...uses inductors and caps to provide a bit more realism for more attenuation) for all the high wattage builds.

Cheers,

Nish

diydude · August 31, 2005, 09:52:19 PM

Quote from: stankyfish
Quote from: aronI'm also sorry to say that every attenuator is not as good as the real thing cranked so unfortunately that's what we need to deal with right now.

In some cases, the change might be for the better for some people, but the attenuator usually makes the amp less "alive".

Maybe time spent on building an attenuator would be better spent on an iso box so you can crank the amp and let the magic happen naturally. The iso boxes I've seen seem to be way overpriced compared to what you get.

Saw Junior Brown live once...got right up there next to the stage to check out his equipment. He had some kind of thick cloth quilt that fit perfectly over the front of his Fender Twin. A small hole was strategically placed in the quilt that allowed a single SM57 to butt up against the original Fender speaker cloth. Then he had his guitar sent thru the monitors at a lower level (I think). What a superb natural power tube overdrive sound!!!

sir_modulus · August 31, 2005, 11:10:25 PM

I once saw an idiot with a metal band trying to crank a twin with a an ancient dod grunge pedal infront of it....damn them fenders are loud buggers! :shock:

Cheers,

Nish

aron · August 31, 2005, 11:30:16 PM

Yeah, Fender amps can be amazingly loud. My Blond Bassman can be really loud when pushed with a Shaka!

WGTP · September 01, 2005, 10:02:10 AM

Don't some of the big time guys use an attenuator after their 100w plexi and then run the signal thru line level effects into big power amps (possibly solid state, since they aren't supposed to be coloring the sound) and then into 4 4-12 cabinets to get a processed studio sound?

stankyfish · September 01, 2005, 10:07:42 AM

Quote from: WGTPDon't some of the big time guys use an attenuator after their 100w plexi and then run the signal thru line level effects into big power amps (possibly solid state, since they aren't supposed to be coloring the sound) and then into 4 4-12 cabinets to get a processed studio sound?

I had read that the guitarist from Queensryche (playing live) would run his amp into a 4-12 iso cab for loading purposes only, and take a direct out into the board - so there was no actual speaker miking at all.

petemoore · September 01, 2005, 11:36:41 AM

Get a super heavy duty watt handling 4'' or as small a speaker as you can find that'll handle the amp, then put it in as small a cabinet as you can make for it, 'seal' the cabinet for sound [using wood or something] so that it isn't loud enough to be heard. Use That as a power soak...
Match or mismatch the ohmage to your speakers for a lo/hi switch, or also add a some lesser resistance for 'some' fine tuning of attenuation levels, and a more constant resistance type sound.
If the ohmage of the PS described is the same as the speaker cab, the speaker cab will share 1/2 'n 1/2 of the power from the amp. If the PSoak is 1/2 the ohmage it'll soak up the lions portion of available output, your speaker cab will be 'quiet' at high output levels.
If you start with an odd' ohmage for the Psaok dummy cab, this will make all the sharing numbers change...you can work with it to get the right amount of soak/output left for the soundcab.
Don't exceed the min ohmage rating on the output section of your tube amp.
I had a resistor attenuatoin a sound man gave me...got hot like stove burner, had large brick resistors in it, and a rotory switch, changed the 'timbre' a good bit at 'more attenuation' settings.

Dave_B · September 02, 2005, 09:24:32 AM

Quote from: petemooreGet a super heavy duty watt handling 4'' or as small a speaker as you can find that'll handle the amp, then put it in as small a cabinet as you can make for it, 'seal' the cabinet for sound [using wood or something] so that it isn't loud enough to be heard. Use That as a power soak...

Would it be possible to remove the cone, or at least cutout a large portion of it, to reduce the sound level? Is the cone needed to keep things aligned? (I know very little about driver construction.)

sir_modulus · September 02, 2005, 10:06:51 AM

enter the weber mass...it's the speaker mass...just the voice coil assembly designed to run with no cone. It provides a responsive load that sounds more like a speaker.

Cheers,

Nish

Dave_B · September 02, 2005, 10:14:06 AM

Quote from: sir_modulusenter the weber mass...it's the speaker mass...just the voice coil assembly designed to run with no cone. It provides a responsive load that sounds more like a speaker.

Cheers,

Nish

That's what I figured, but for us DIY'ers, I didn't know if there was a pole piece or some moving part that relied on the cone to stay aligned.

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