Help Understanding Impulse Response and Cab Emulators (repost from Lounge forum)

mrspag

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274
So I'm kind of new to the world of modern day multieffects processors. I bought a Boss GT100 last year and it has replaced my pedal board live. I love it. I run it straight into a peavey tube amp or an ac30 depending upon the size of the venue into the send return. I find that I like setting the gt100 output to direct so that I get the speaker emulation with the preamp. As we are now playing larger venues and are mixing everything I'm interested in running it direct. I know from running the gt100 direct into the small board and PA in the practice space we have and, also from runnning it direct with headphones, that it doesn't sound as good as running into a tube amp. When I run it direct I go from the guitar cable mono out on the gt100 to the board with a guitar cable.

I was thinking of getting a passive DI box and then I ran across the Palmer PD 109 The Junction DI box. It seems to be better suited because it has an analog cab simulator. This of course caused me to research on the web and TGP and find out about the two note cab pedal, the amt Pangea, and the whole impulse response thing.

So, I'm really not sure where to go. What is the best solution for using the gt100 direct into a board for live or recording. I see that the more expensive effects like the helix and the ax8 have a balanced out and built in IR. Would using one of the standalone IR boxes or the Palmer DI and the gt100 be a similar solution? I'm really not sure which way to go. I don't mind spending money I just don't want to spend it on stuff I don't need. I really like the sounds I get from the gt100 and the preamps it has.
 

Multicellular

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7,880
So if you are running into an amp on stage, I don't understand why you'd want a cab IR. Your ac30 or Peavey have cabinets. An IR might be used if you are running direct into the PA because the PA has speakers that are 'full frequency'. Guitar speakers, in contrast, really attenuate some frequencies, highs in particular. For recording, if it were me, I wouldn't add a piece of gear on stage, I'd record it direct and use one of the even free IR loaders available in the DAW. For fancy, Recabinet or the cabinet tech in Amplitube 4 also simulate some of the dynamic properties of speakers that IRs can't.
 

mrspag

Member
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274
So if you are running into an amp on stage, I don't understand why you'd want a cab IR. Your ac30 or Peavey have cabinets. An IR might be used if you are running direct into the PA because the PA has speakers that are 'full frequency'. Guitar speakers, in contrast, really attenuate some frequencies, highs in particular. For recording, if it were me, I wouldn't add a piece of gear on stage, I'd record it direct and use one of the even free IR loaders available in the DAW. For fancy, Recabinet or the cabinet tech in Amplitube 4 also simulate some of the dynamic properties of speakers that IRs can't.
Thanks for helping me understand the difference. My thought with getting the cab IR was to run direct to the board, without the amp onstage being mic'd, and either getting a box that does the cab IR or the Palmer type unit that has the analog cab emulation. Instead of going straight from the boss gt100 mono guitar cable out to the board unbalanced. I'm trying to find out if either DI option would improve the sound direct over the boss gt100 straight to the board.
 

Multicellular

Member
Messages
7,880
Thanks for helping me understand the difference. My thought with getting the cab IR was to run direct to the board, without the amp onstage being mic'd, and either getting a box that does the cab IR or the Palmer type unit that has the analog cab emulation. Instead of going straight from the boss gt100 mono guitar cable out to the board unbalanced. I'm trying to find out if either DI option would improve the sound direct over the boss gt100 straight to the board.
Yes that is right, a cab ir if your multiFX doesn't have cabinet emulation could sound better direct to board. Forgive me if I misunderstood your first post.

What I don't know is if the gt100 has cab emulation or not.
 

mrspag

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274
The boss gt100 has cabinet emulation but it's not IR. You can play around with the cabinet size, a couple of different mics, and the distance and placement of the mics from the cabinet. It's not the best.

So, let me make sure I understand this (after reading some other recently posted great threads that are discussing this, too). My boss gt-100 doesn't have a balanced out. So, if I wanted to use IRs for the cabinet emulation I'd turn off the cab emulation on the boss gt100, go out from the output mono to something like an epsi, and then into maybe a passive DI box to the board?

If I have that right, would the IR improve the sound enough to make it worth it, in theory (I know it's subjective)?
 

Lele

Member
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1,604
The boss gt100 has cabinet emulation but it's not IR
Most (or any among the modern devices) uses IR convolution to simulate cab+mic, because it's easier and efficient. But often the IR data are too small (too few), because of the calculation load in real time, and the result can be not very realistic or accurate. Even if you can't load customized IR files, it does not mean that the GT100 (or any other similar multi-fx) does not use some ROM with this type of data.

My boss gt-100 doesn't have a balanced out. So, if I wanted to use IRs for the cabinet emulation I'd turn off the cab emulation on the boss gt100, go out from the output mono to something like an epsi,
Yes!

and then into maybe a passive DI box to the board
This is what I don't understand. Why do you need a passive DI box? You could go directly from the EPSI (or AMT CP100) into the mixer.

If I have that right, would the IR improve the sound enough to make it worth it
Big question... o_O Even if using custom IR files will give you more accurate tones similar to a real speaker+mic situation, nothing will guarantee that you will like it better...

PS: if you have a PC, and a DAW software, you could try to use it to treat your GT100 sound (without its own cab emulation) through IR convolution, and see if it is a better solution for you. So later you can decide if a IR convolver is worth your money/time.
 

eriwebnerr

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2,670
PS: if you have a PC, and a DAW software, you could try to use it to treat your GT100 sound (without its own cab emulation) through IR convolution, and see if it is a better solution for you. So later you can decide if a IR convolver is worth your money/time.
Agreed - start here. Play your GT100 with cabs off then load an IR into a plugin to see what you think. I thin Ownhammer and RedWirez both have some free IRs you can try. In any event you should be able to find sone pretty decent free IRs or a V30, Greenback and or CElestion Blue for reference. Then you can load those into a free IR loading software like LeCab2 by poulin. I also think Two Notes has a free version of their software you could check out.
 

mrspag

Member
Messages
274
This is what I don't understand. Why do you need a passive DI box? You could go directly from the EPSI (or AMT CP100) into the mixer. said:
From looking at the EPSi it looks like it doesn't have a balanced out. Isn't it better to run direct into a board with a balanced out, so I would need a DI box?
 

Lele

Member
Messages
1,604
a passive DI box to the board
I think most players would not have any benefit with an additional DI box.
The output of any multi-fx is not hi-impedance like the pickups any more, so noises and interference should not be an issue.
Anyway, I can say, I never used any DI box after my multi-fx or preamps into the mixer.
 




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