Login / Register  0 items | $0.00 NewWhat is KVR? Submit News Advertise

IR vs Cab

jm1
KVRer
 
15 posts since 24 Jun, 2015

Postby jm1; Fri Aug 18, 2017 3:44 pm IR vs Cab

Hi, I have always wondered how IRs compare to a recording a live cab, specifically with dynamics. From what I understand (and maybe I am way off here), but the IR is created by using a sine wave signal with a sweeping frequency range and then blasted through a power amp to the speakers at a certain level, and I am assuming since each impulse is one file that it was done with one volume level. So my questions are:

1) Are IRs just captured at what the creator thought was the optimal level?
2) How would an IR would compare to a live cab with someone who plays with a large dynamic range?
3). Does the output of an amp sim have the same impact on the cab/IR tone (speaker behavior, cab resonance, etc) of an IR as how playing an amp loud or at a low volume would?

So basically, does an IR stay as dynamically accurate as a live cab...?

Thanks.
User avatar
Kazrog
KVRian
 
853 posts since 24 Oct, 2009

Postby Kazrog; Fri Aug 18, 2017 4:21 pm Re: IR vs Cab

jm1 wrote:Hi, I have always wondered how IRs compare to a recording a live cab, specifically with dynamics. From what I understand (and maybe I am way off here), but the IR is created by using a sine wave signal with a sweeping frequency range and then blasted through a power amp to the speakers at a certain level, and I am assuming since each impulse is one file that it was done with one volume level.


Guitar speakers are 95% (or more) linear in terms of deviation from linearity, which means the relative frequency response curve of a given speaker does not change at any normal level. In other words, a Celestion Vintage 30 (for example) will always have this same relative frequency plot shape irrespective of SPL level:

Image

Of course if a speaker gets physically damaged, this can change a lot - we're talking about a normal range of operation here, though.

The level of an IR capture is relatively unimportant - the most important aspect is to have it loud enough to drown out background noise (especially if you're using a condenser mic.) All Recabinet IRs were captured in an isolation booth at high volume levels (above the pain threshold if you were standing in the booth.)

jm1 wrote:1) Are IRs just captured at what the creator thought was the optimal level?


Essentially, yes. As I said above, it's not worth fussing about too much as it has almost no effect at all.

jm1 wrote:2) How would an IR would compare to a live cab with someone who plays with a large dynamic range?


Same answer - it would be about 95% the same on a bad day.

jm1 wrote:3). Does the output of an amp sim have the same impact on the cab/IR tone (speaker behavior, cab resonance, etc) of an IR as how playing an amp loud or at a low volume would?


It absolutely can and does - a good modeler will emulate the way that tube power amps couple with speakers. Also, on the speaker modeling side, if you're obsessive about accuracy, some dynamics modeling helps complete the effect (which is why I built that into Recabinet.)

jm1 wrote:So basically, does an IR stay as dynamically accurate as a live cab...?


Absolutely. If you set Recabinet's "Dynamics" control at 50%, and toggle the feature on and off, you'll hear what the difference would be in the case of a speaker with fairly substantial deviation from linearity compared to most. It's an effect I like, but most _modern_ guitar speakers are actually more rigid than this. The behavior at 50% models the most nonlinear vintage speaker I could find. At 100%, it's exaggerated by a factor of 2, and at 10-15%, it's about in the range of a modern, rigid as hell Chinese-made guitar speaker.

What's funny is they are building "better" speakers today, but they don't sound as interesting to our ears. It's important to remember that guitar is definitely not hi fi.
Shane McFee
CEO/CTO - Kazrog LLC
jm1
KVRer
 
15 posts since 24 Jun, 2015

Postby jm1; Fri Aug 18, 2017 7:43 pm Re: IR vs Cab

Awesome, thank you for such an excellent explanation!

Moderators: Moderators (Main), Kazrog Mods

Return to Kazrog

Who is online

Users browsing this forum: CCBot (commoncrawl)