instant comparison ultra - tweed twin

psst

psst

Inspired
I have one of these head amp switcher. It's for using one cabinet and two heads, and when you switch to one of them, the other one gets a dummy load.

thpics.jpg


So I used it for a *real* comparison between real preamp and poweramp, and axe's preamp and poweramp (no cabs or mics in the equation here).

For me a A/B comparison is the only valid, anything that takes more than a couple of seconds to switch cables makes you loose the perception of sound, and using two identical cabs it's not valid either, they are placed in different places in the room (even if they are together) and your ears position with respect to them is different too.

So I tried with my HIWATT DR-103 and my Fender "Big Box" '57 Tweed Twin with Axe's emulations of those same amps.

Axe goes to a non-valvular power amp, pretty linear (a Crown).

The Hiwatt was easy to get exactly the same sound, to the point I was playing rhythm and switching and it was not possible to know if I switched or not. Using a real Fuzz Face in front of them gave exactly the same sound too.

hiwatt-71-010.jpg


Then I tried with the Tweed Twin, after playing a little bit with the Damp and presence, I could get exactly the same sound too in clean.
When I pushed the Drive in the real one, there was a very small difference in the upper highs, but almost exactly the same sound.
Explanation could be that the one in the Axe is the Bassman Tweed, and although they are exactly the same circuit, the difference between them is the transformer and double number of power tubes (one has to feed a 4x10 cab and the other a 2x12).

TTHP_BigBox-5F8-A-1960.jpg


Pretty happy with this thing. Next I'll try with my Dual Rectifier trem-o-verb.

Also next thing is making IRs of my cabinets. I already did that with my Hiwatt cabinet, and after some different reference mic re-positions and experiments (two meters away from the cab, more or less) I could get a IR that really sounds like a "real cab" sound through my FRFRs. Could not get it with the "official" cabs in the Axe, but now I'm completely happy.
 
That's how I test the models.

The issue I've had with the older amps, especially Fenders, is the variability from unit to unit. No two sound exactly alike. I attribute this to the rats nest wiring. The old Fenders tend to have resonances in the power amp, most likely due to parasitic feedback. This causes a peak in the frequency response at a high frequency. I have a way to model it but since it's so variable and inconsistent I don't use it. I've also found that if you like that sound you can replicate it with some EQ after the amp block. Use a peaking EQ around 10K with a fairly high Q. Adjust freq, gain and Q to taste.
 
Once again, a methodical process shows just how close you can get with the Axe-Fx, if that is your intent. I've done the same comparison with tube amps I own, using an IR of the cab that I acquired myself, also at a mic distance of ~2 meters, and comparing Axe-Fx/FRFR to the amp. It is true that the two cabs being in different positions has an effect, but the difference due to position is small and can be controlled for by reversing the two and comparing again.

I was not interested in perfectly cloning the sound of one example of a tube amp with a specific set of control settings - that is not possible with another example of the same model amp - only in satisfying myself that the Axe-Fx can replace a tube amp to my satisfaction. It can, and it can also make amp sounds that you would be hard-pressed to get from any physical tube amp.
 
That's how I went about comping my wah.

I've actually done staight A/B testing with my recorded tones from tracking in years past to match them on the same monitors. I can (and have) nailed pretty much every tone I have loved getting over the years with my rigs. And a straight A/B for me is of recorded tones. Then I improve on them to match my taste.

For you to do it with a live amp and the Axe-FX is even deeper down the rabbit hole.

And the key to all this IMHO is to think like an engineer; put EQ and (some) effects AFTER THE CAB. You can do things in any manner of ways; it's fun to be able to create what you want too.
 
Great thread. But, I have to admit that I was hoping to scroll down and see sound clips demonstrating it. Do you have any?
 
I love this stuff. Great post, psst.

The wonderful thing about the Axe is that it's capable of sounding so much like a tube amp that you can't tell the difference (and many different tube amps at that, including some that don't even exist), and yet it's also capable of doing so many other things that a tube amp could only do with difficulty (and some time with a soldering iron) or not at all.

The info about parasitic feedback is really useful to know, too.
 
psst said:
Also next thing is making IRs of my cabinets. I already did that with my Hiwatt cabinet, and after some different reference mic re-positions and experiments (two meters away from the cab, more or less) I could get a IR that really sounds like a "real cab" sound through my FRFRs. Could not get it with the "official" cabs in the Axe, but now I'm completely happy.
Click to expand...

And after that post these presets.
Well, I've tried to put some smilies but I don't know how to do that........
 
Brian G said:
Any chance that you could share the cab IR you made?
Click to expand...

Of course.
http://www.pinktones.net/psst/hiwatt-alf.syx

Cabinet: 2x12, closed back. 70's Fane drivers.
Flat response microphone, 1.90 meters from the cabinet, pointing to the center (not center of a speaker, center of the cabinet, between both speakers). Sweep through a Crown power amp (non valvular, of course).

I don't know if it's useful for anyone but me, cause I really think cabinet sound is very personal, and it varies *so dramatically* moving the mic that there's not "one sound" of the cabinet but a lot of them to choose from. This is the one I chose.
 
psst said:
Cabinet: 2x12, closed back. 70's Fane drivers.
Flat response microphone, 1.90 meters from the cabinet, pointing to the center (not center of a speaker, center of the cabinet, between both speakers). Sweep through a Crown power amp (non valvular, of course).
Click to expand...
What were the elevations of mic and cabinet from the floor?
 
psst said:
"Floor" of the cabinet, around 50cm elevation. Mic, 50cm + half the height of the cab.
Click to expand...
That means there is a floor reflection in the IR. If you zoom in and look closely at the signal trace in a .wav editor, you will see a peak about .7 milliseconds after the first peak in the IR.

The effect of a reflection with this time relationship to the direct sound is a cancellation around 700-800 Hz, then at 3 times, 5 times, 7 times, etc., that frequency. This behavior may not be objectionable, but it can be eliminated by placing the nose of the mic on the floor (assuming a hard, non-carpeted floor), aimed in the direction of the speaker. In this scenario, called a "ground plane measurement," the floor reflection occurs such a short time after the direct sound (typically on the order of microseconds), that its only effect is to create a frequency-independent 6dB increase in the SPL seen by the mic.

If you use the ground plane technique, you still can get reflections from nearby walls within the 21.3-ms window of a 1024-point IR. You can eliminate those if your test space is large enough by placing mic and speaker 3 or 4 meters from the nearest room boundaries.
 
I was going to say the same thing Jay said...but since he already said it- there is no need for me to do the same ;)

I did an A/B awhile back with a Blackface- I determined for myself at that point there was no need for me to ever do that again...The axefx nailed it.
I still enjoy hearing these stories.
 
Jay Mitchell said:
psst said:
"Floor" of the cabinet, around 50cm elevation. Mic, 50cm + half the height of the cab.
Click to expand...
That means there is a floor reflection in the IR. If you zoom in and look closely at the signal trace in a .wav editor, you will see a peak about .7 milliseconds after the first peak in the IR.

The effect of a reflection with this time relationship to the direct sound is a cancellation around 700-800 Hz, then at 3 times, 5 times, 7 times, etc., that frequency. This behavior may not be objectionable, but it can be eliminated by placing the nose of the mic on the floor (assuming a hard, non-carpeted floor), aimed in the direction of the speaker. In this scenario, called a "ground plane measurement," the floor reflection occurs such a short time after the direct sound (typically on the order of microseconds), that its only effect is to create a frequency-independent 6dB increase in the SPL seen by the mic.

If you use the ground plane technique, you still can get reflections from nearby walls within the 21.3-ms window of a 1024-point IR. You can eliminate those if your test space is large enough by placing mic and speaker 3 or 4 meters from the nearest room boundaries.
Click to expand...

I think that I'll bring one of my 4x12s outside and do a 20sec sweep, just to see how that would sound. What do you think, Jay? Since it's a sweep file, the outdoor ambience should be of less importance, and it's a parking lot, so the space is big enough.
 
FractalAudio said:
The old Fenders tend to have resonances in the power amp, most likely due to parasitic feedback. This causes a peak in the frequency response at a high frequency. I have a way to model it but since it's so variable and inconsistent I don't use it. I've also found that if you like that sound you can replicate it with some EQ after the amp block. Use a peaking EQ around 10K with a fairly high Q. Adjust freq, gain and Q to taste.
Click to expand...

I aded an EQ, put like 7db or so in the 8KHz and now it's spot on, both clean and dirty, no difference at all doing A/B.

Also I spent some time comparing the Orange channel of my Dual Rectifier and the Red channel with the Axe's counterparts. After some time tweaking, I could nail it too (just with the AMP block, nothing else, the only exception I did is the EQ after the Twin as I said in the previous paragraph). Had to turn "Deep" quite high, like 6.5...

It would be nice to have the Blues channel too, I like it.

The Clean channel was easy with a Blackface block.
 
Please post your Hiwatt patch. I would like to A/B it with my DR-504. I have a similar set up with a Radial Cab Bone pedal so that I can A/B the Axe with other amps. I was able to "nail" my Marshall 1987, Fargen Miniplex 2 and Randal MTS Plexi module. In fact, I actually preferred the sound of the Axe when all was said and done. Basically, there are such minor differences between the Axe and the real deal that it is difficult to say one is actually better than the other.
 
FractalAudio said:
That's how I test the models.
Click to expand...

I really would encourage you to post the results as patches and place them online or better introduce a bank of dry amp models as they could be a really good starting point for most of the users!
 
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