Speaker Resonance Controls

hi,

first post here. Cool threat, very informative.

While waiting here for my unit, and look on the graphs on the first page..hmm...with my very little electricity knowing:

Could it be that the little impedance lines with there behavior between 1k and 5k in consumption with the output-transformer (in real world) have to build some little transients? The transformer and the speaker-coil are together a resonant circuit, or not?

While playing with the guitar through these frequency band, this have to react, very minimal, as result maybe more dynamic/live-feel?...or i'm wrong?

best regards
frank
 
Absolutley love this thread. I would love to see a regular "lesson" on the forum as others have suggested. Kind of goes along with the Fractal University 101 thread that GuitarDojo started in the News and Announcements / Read Me section.

Anything that helps me/us understand how to get the most out of our unit is appreciated.
 
Last edited:
tried this out .. works very well :) just like revoicing the amp but not like 1 dimensional with an eq
 
This info is great, thanks Cliff.

Cliff mentioned he does not use the eq for his patches generally now but uses the resonance controls to "eq".

I tried that with good success but had a pretty radical shift downward in high freq resonance, like from 14k to 5.5k for a VHT More higher gain patch.

I like the result but notice that most patches have high freq resonance form 13k to 19k.

Anyone know of any graphs showing the higher order network from real amps such as a Marshall into 4-12 greenback, v30s etc. Or Fender bassman etc into a few cabs?

How radical are people getting in using these parameters to eq their patches?
 
Last edited:
My observations in this post is only for high gain patches!

When I run my Axe II through studio monitors, Adam A7X, then Speaker resonance tab very useful in shapeing the tone. I use it a lot and I follow Scott P suggestion when creating tones.
In contrast with SS + Cab, in my case Matrix GT800FX + Mesa 4x12 V30, I've found out this tab is useless. It took me a while before I realized that it was that setting which made ​​it impossible to get a natural sound. I've owned some nice amps through the years: mesa triple rectifier, mesa MarkIV, 5150 and triaxis...

I could not understand why the sound was so digitally through the poweramp when the tone from the Adam and the recordings sounded great! I had in mind to pick up triaxis + 2:90 again and only use Axe II for effects in my live rig. I even tried new cables, another poweramp and different cabs.

I've read many topics where users have encountered the same problem as me and finally I read somewhere(!) to lower the speaker tab settings. That's when I tested to flat Speaker resonance curve and added a 12db bass boost peq. Wow, finally! Now it sounds like a real preamp. Recto finally sounds like a recto from the poweramp!

Question: Speaker Resonance tab is the only FRFR solutions (and recordings)?
 
Last edited:
shotgunn said:
I still don't really know what I'd be listening for. I've been timid and have avoided tweaking these parameters so far.
Click to expand...

That's one of the great things about the x/y settings... Copy x-->y and tweak y, then compare to the untweaked x to see what the settings do. I didn't know what I was listening for, now I've graduated to "slight understanding."
 
FractalAudio said:
These controls are so powerful that I made a separate GUI page and graph for them. Don't overlook their importance in your tone-shaping quests. I always start with these before resorting to the graphic EQ or EQ blocks (in fact I almost never use any EQ). If you have some favorite speakers you can try to find published impedance data to help match the response. I use a device called a "Woofer Tester" to measure the impedance of speakers. About a $100. Probably not something for the casual user though.
Click to expand...

This is the kind of stuff we can really use. I "forced" myself to go through every page of the menu and this was one that surprised me.

Now I'm thinking poor man's woofer tester: "simple transconductance IC circuit for $5", use a flat sine wave sweep from computer program used to take IRs (or even the AXE IR sampler!) passed through the transconductance IC amplifier then applied to the speaker terminals, record the output voltage of the sweep applied to the speaker terminals, deconvolve to create an "IR" of the speaker's "transconductance response", use Alberts program to determine the impedance curve. Transconductance ICs are available for a few bucks. If you're good with a soldering iron and can etch boards it should be a piece of cake unless I'm missing something. A few resistors and small caps, a 9 volt battery to power it, 1/4" input and output jacks in a small box and your gold.

Let me have my coffee and think about what I'm missing!
 
Last edited:
(sigh) I am stumped. I cannot figure a way to explain this one. It is not *exactly* as it might seem based upon description (to me at least). I usually back this parameter down a bit to allow the amp to "breathe" a bit more, usually .8-.9 (no rules, just a starting place). Over "1" usually feels way too claustrophobic for me. As far as the relationship of this with Speaker Impedance.. very, very subtle IMO.
 
Cliff explained it Nikki and I missed it. My mistake.

From the manual:

"At lower settings (of Transformer Match) the
speaker resonance will be more pronounced, at higher settings the speaker resonance will be less
pronounced."

This is not what I am observing. There is zero change in the "pronouncement" of the speaker resonance as the Transformer Match parameter is changed.

UPDATE: My questions got answered earlier in the thread, shame on me for not reading more carefully, but I think the manual is wrong per the above and per Cliff's statement that only the primary impedance of the OT is changed.

No big deal - I like the controls very much!

Thanks.
 
Last edited:
FractalAudio said:
Yes, the speaker resonance stuff changes the virtual impedance seen by the virtual power amp.

Transformer matching sets how much impedance is reflected to the tubes. The higher the matching, the greater the impedance seen by the tubes. IOW, it's the OT primary impedance. Most amps are usually well matched or slightly under-matched. Some amps, like Trainwrecks, are over-matched. The primary impedance is quite high. This causes the power tubes to go into clipping easier.
Click to expand...

I thought I read this thread but I missed this. That answers my question. It's designed to change just the OT's primary impedance.

That's cool. I actually like that better, but I still think the manual is wrong.

Nevermind!
 
Last edited:
No offense to your questions but I don't think the average guitar player really gives a hoot about this. I think your over thinking this. Time to play your guitar and not worry about it.
 
DaveP said:
No offense to your questions but I don't think the average guitar player really gives a hoot about this. I think your over thinking this. Time to play your guitar and not worry about it.
Click to expand...

No offence taken.

There's nothing stopping you from simply passing over my posts once you realize you aren't interested. I agree, the average guitar player doesn't give a hoot, nor do they understand how amplifiers work. But there are a few who do care and who do understand, or who want to learn to understand. Some of us know how real amps are built and how they should behave, and knowing this information makes it easier to get tones we want instead of randomly turning data wheels until we get lucky.

Again, no offence taken, and no offence intended

Thanks for the feedback. I deleted my redundant posts.
 
Last edited:
Anybody ever figure out where the speaker resonance has to be set for the stock cabs? Posted anywhere?
 
zentman said:
Anybody ever figure out where the speaker resonance has to be set for the stock cabs? Posted anywhere?
Click to expand...

I asked about that a couple of times, to provide the Amp -> Spkr settings for the factory cabs.

To my knowledge, this hasn't been posted by anyone so far.

Richard
 
barhrecords said:
I asked about that a couple of times, to provide the Amp -> Spkr settings for the factory cabs.

To my knowledge, this hasn't been posted by anyone so far.

Richard
Click to expand...

I don't think we'll ever get that information. When Cliff said "use your ears" that told me that the info probably doesn't exist. It's highly unlikely that all (if any) of those cabs were tested for impedance and documented. Who even knew at the time the RW and OH IRs were taken that speaker impedance would be an exposed, adjustable parameter?

Also, the mic placement probably has more of an effect on the frequency response (excepting FFs) than the speaker impedance.

Just my 2 cents.
 
Thanks for this information!!! Truly valuable! Amazing results!

I have been studying amp design recently, as I realized my knowledge on the subject was minimal. Although I still have only a tiny bit of knowledge on the subject, I find that it helps me understand posts like these.

This control has a profound effect on the speaker-amp combination on many levels.

Thanks for the info, and such an amazing machine!
 
You must log in or register to reply here.
Back
Top Bottom