Is anyone here using load boxes and impulse response to record their guitars?  
 
I ran into this great video by Pete Thorn on the subject and I'm fascinated by it, but I barely understand it.  I'm a line out DI kinda guy, because I have never, ever been able to mic a guitar cabinet and even get compromised results, much less anything satisfactory and I do not live in a situation where I can drive my room with a tube amp anyway.  
 
I understand the load boxes, it's the impulse response set up that's confusing to me.  Does anyone have experience with this and how do you like the results?  
 

I generally use a similar sort of setup, but slightly different.

The amp's speaker output connects to a Palmer speaker emulating DI box. The XLR out from the DI goes to the interface, the speaker out to a Palmer load-box. I could use a single Palmer combination DI and load-box, but I bought them at different times so I don't.

As a setup it works pretty well, though the Palmer DI leans towards a more Celestion speaker eq curve with flat mids and a treble boost than a Jensen response - the deep mid-scoop Jensens have is missing and Palmer's "American/Mellow" setting just rolls off huge amounts of treble and is quite unlike a Jensen. Adding eq in the DAW can put in a Jensen-style mid scoop centred around 500Hz when necessary. The DI box doesn't have a flat setting that doesn't impose an eq/response curve on the XLR output, so further speaker modelling isn't an option unless the Palmer's curve is first compensated for in eq. I dont add a fake microphone in because I regard the mic as a compromise that's necessary to capture sound in moving air, but not something to add in when it's not needed just because I'd have to use a mic to record a "real" speaker.

For bass I use an MXR bass preamp, then if I find it helps, add a fake speaker in the DAW, either using impulse responses or just a speaker cab in Amplitube/whatever. Again, it works pretty well.

The big advantage of DIs that take their feed from the amp's speaker outputs rather than a line out from the pre-amp is you can crank the amp a bit to get the power-amp and its valves saturating, which is a different sound and feel to pre-amp overdrive. Just never be tempted to run a valve amp without the correct impedance load on the speaker outputs. A transistor amp is likely to survive the experience, depending on it's design, but a valve circuit will take damage, quite possibly very serious and expensive damage.

A guitar amp generates distortion three ways: the triode preamp (odd-order harmonics), the push-pull power amp / transformer (even-order harmonics), and the speakers (odd-order and intermodulation distortion). When you take a line out signal, you're only getting the preamp distortion. When you use a microphone in front of the speakers, you get all three, which is why it's usually preferable for distorted tones.
 
The problem is that you have to push a power amp very hard before it starts to deliver juicy distortion, because you have to pump enough current through the transformer to saturate it. That means cranking it up, which is often impractical.
 
Placing a dummy load (usually a large resistor) in place of the speakers allows you to push the power amp hard, but silently. 'Now, you at least have two of the three distortion sources working for you. But you still don't have the desired speaker/cabinet distortion. You also don't get whatever the room and microphone might have added to the tone.
 
Using an impulse response allows you to emulate the contribution of the speakers. Because the IRs were created using real microphones in front of real speakers in a real room, the convolution processor is able to accurately reproduce the effects of a specific speaker/microphone/room combination. Best of both worlds, in theory.
 
The downside is that you're stuck with the IRs you have and can't do much to alter them. With microphones, you might find that the tone can be improved by moving the microphone an inch or two. But that's not an option if you're using an IR, which is a snapshot of somebody else's setup.
 
Pete Thorn is taking it one step further and creating his own IRs. That's a lot of work, and you may find that you can get acceptable (or even better) results using other peoples' IRs. That way, you're not limited to the equipment you own personally. Maybe you want the sound of a Marshall with a ribbon mike one day, and a Twin Reverb with an SM-58 another day. 

Thanks Bit.  That's a great explanation.  I noticed Pete is using a Two Tones plugin for his IR file, in Logic as his DAW software.  I'll have to do some research to see how this will work in Cakewalk.     
 
Sounds like I would really benefit from others IR's.  I love the purity of doing my own, but like you say, it's a lot of work and I'm not sure that cost / benefit really justifies it and you can get a lot of variety, via from people who know what they're doing when mic'ing cabinets.  
 
I think I need to at least hear a good tube amp with a reactive load.  
 
Not so funny story....so when I got robbed a few years ago, I bought a Mesa Boogie Rectoverb 50W 1x12 tube amp with the insurance money and fell instantly, deeply in love.  But all my experience had been with a Marshall Valvestate 8100 SS output to a cheapo Behringer DI box with cab sim.  Since I always recorded DI, I simply set up my Mesa the same way.  And because I'm a complete dumbass, I disconnected the speaker....you know where this is going.  
 
They said I didn't fry the transformer but I swear it never sounded the same.  
 
But, I have to say, that line out sound was still better than anything I've been able to accomplish with my Marshall. I'm dying now to know how that Mesa sound would improve with a reactive load.  And then, with a good IR instead of that silly Behringer cab sim.  I do remember being disappointed at how flat and compressed the sound was compared to what I was hearing out of the cabinet.
 
 

all of my recordings i've posted,
and the ones on my last 2 albums,
were mostly recorded using a Mesa Boogie Mark IIb 60 watt tube head...
amplifier speaker out into a palmer PDI-09 (it has a filter cab EQ, same as TLW describes).....
PDI-09 'thru' and into a WEBER MASS LITE attenuator.....
out of attenuator and into speaker cabinets....
 
xlr out of pdi-09 capture the full output of the amplifier, and goes directly to DAW Interface (either into a mic pre and into my soundcard, or directly into my soundcard from the pdi-09)
 
so, basically, i can run the amp as hard as i want, capture the tone, but after that happens, i can attenuate the level of volume thru the cabinet at any volume i want, and it does not effect the direct capture.
 
it also means that i can capture TWO signals at once; a direct signal, and if i want, a miced cab signal, which i can then blend in any configuration i want.
 
 
i can detail this more for you, if you like, 
but the bottom line is, i'm not using modelers or IR's, tho i think pete thorn's stuff sounds AWESOME.
 
 
 
here is a quick little vid i did recently,
just to learn how to edit a video and pull audio from Sonar into it..
 
one side, is purely direct.
one side was close miced with a Shure KSM44.
 
 

batsbrew
all of my recordings i've posted,
and the ones on my last 2 albums,
were mostly recorded using a Mesa Boogie Mark IIb 60 watt tube head...
amplifier speaker out into a palmer PDI-09 (it has a filter cab EQ, same as TLW describes).....
PDI-09 'thru' and into a WEBER MASS LITE attenuator.....
out of attenuator and into speaker cabinets....
 
xlr out of pdi-09 capture the full output of the amplifier, and goes directly to DAW Interface (either into a mic pre and into my soundcard, or directly into my soundcard from the pdi-09)
 
so, basically, i can run the amp as hard as i want, capture the tone, but after that happens, i can attenuate the level of volume thru the cabinet at any volume i want, and it does not effect the direct capture.
 
it also means that i can capture TWO signals at once; a direct signal, and if i want, a miced cab signal, which i can then blend in any configuration i want.
 

Thanks, I'm pleasantly surprised at your recording chain. I just figured you mic'd everything. That's very encouraging. Loved the vid.

So on your mic'd side you have a cabinet and speaker keeping IR from having a job. Your DI side won't but it still has two of the three elements Bit was talking about, mixed with your mic'd side.

It's a great sound.

Now, Pete says that your output from your DI is affected by the load characteristics connected to the amp. The more resistive the load, the flatter the impedance characteristic. So it sounds compressed and dull.

He actually demonstrates this on the video above, around 13 or 14 minutes I think.

I would think then, the more you turn up your attenuator, the more resistive the load will become, and the tone and sound should change on your DI side.

but remember..
 
i'm taking the palmer feed directly off the speaker out of the amp....
 
before it hits the attenuator.
 
that fact is key.
 
 
the palmer is applying a 'hardware' version of a IR..... it's a EQ circuit, that implies the tone of a miced 1x12, 2x12 or 4x12.....
 

so, the attenuator is not really doing anything until after the palmer has already gotten it's signal..
 
also, the mass lite, uses a speaker motor for it's load.... in addition to 'some' resistive load, it does not work like a thd hotplate, or marshall power brake, that kind of thing...
 

The particular impedance loading a loadbox, which completely replaces a speaker, unlike an attenuator which lowers the volume that reaches the speaker, should make no more difference to the amp's sound or volume than using an 8 Ohm speaker rather than a 16 Ohm. Assuming the speaker or loadbox is connected to the correct output on the amp, of course.

The Palmer loadboxes have an advantage over some others in that they're not simply a bank of fixed resistors an a heatsink but they present a reactive load to the amp which is much closer to the real-world load a speaker presents. They can also reliably handle pretty hefty amps, which might be useful if someone's only amp is a 100W 1960s or 70s Marshall or a Blackface Twin they like to crank to get the power stage working hard.

And while I've yet to damage a valve amp by forgetting to connect the speaker I have had a couple of solid state amps burn out in the past because of a short in the speaker cable. In one case because the lead got accidentally tripped over an pulled from the cab - no worries, it'a a solid state amp, except - the person who tripped over the lead then stood on the jack plug, squashed it and pushed the connectors inside it together. The other one was a rubbish jack plug that allowed its connectors to move enough for them to touch.

batsbrew
so, the attenuator is not really doing anything until after the palmer has already gotten it's signal..
 
also, the mass lite, uses a speaker motor for it's load.... in addition to 'some' resistive load, it does not work like a thd hotplate, or marshall power brake, that kind of thing...
 

Ah, I see what you're saying.  But keep in mind, these are audio 'circuits'.  Outputs and inputs are just how we describe the signal flow conceptually, but inputs and outputs make a circuit together, and each effects the other.  
 
Something has to provide the load to your amp, and I believe that is your attenuator.  Your Palmer is providing connection to your load speaker, or attenuator in this case, on your Thru input.  So, the output of the Palmer is effected by the kind of load you have connected to its Thru input.  
 
And it would be super easy to test.  Just disconnect your attenuator / speaker circuit *for a second* and listen to the sound change.  With no load, it should be effected.  If Pete is correct about this, the load characteristics will change the audio circuit the Palmer is getting its sample from.  
 
It's not something that was obvious to me, at first but after listening to Pete explain it and demonstrate it, and then considering electrical theory, it all makes sense now.  Pete also posts in the Rig-Talk forum and he explained this amp/load relationship with respect to line-out capture, in writing to another poster:
 
http://www.rig-talk.com/f...c.php?f=3&t=166679
 

"But you can't "take the load out of the equation"- just because you put the ISO line out box 1st after the head, the amp still reacts to whatever it's being loaded with, downstream, so to speak... and that affects that line out sound. Even if the line out box is right after the head's speaker out. And it makes a big difference (the load). The difference between a decent reactive load and a resistive load is quite big, your grandma could hear
it.  ok, my grandma...." 

 
Every time I say "Pete said" I hear my little sister "Mom said!!"  ha ha