| Author |
Topic: Speaker selection using a DAW for emulation of EQ curves |
Helmut Gragger
From:
Austria
|
Posted 4 Feb 2013 11:50 am |
|
(I nearly had forgotten that I had made this write-up  )
Preface:
Many years ago I was looking for a steel guitar amplifier rig, in times before everything abounded in internet.
There were a few specimen available (mostly the same as today), which all were equally excellent if you believed in their marketing.
At this time I was in contact with a guy abroad, a private person, who was dissatisfied with what was available and had a company make a steel guitar amplifier plus cabinet according to his specifications. He claimed that this was much superior to all others and I bought one.
It was not cheap, and while I still use the head, I hated the speaker from the beginning.
It was a 15“ speaker with an aluminium dustcap (allegedly for more treble) not unlike the ones used today in an undersized cabinet. A typical (pedal) steel guitar arrangement even today.
Recently I built my own cabinet with a 12“ PA speaker (Eminence Delta Pro 12A) in a „detuned“ cabinet according to the specifiations of Kevin O´Connor from Londonpower in Canada.
A detuned cabinet is similar to an open back cabinet in some way, except it is open to the front. It also has similarities with a stock 2x12 cabinet.
This approach has many advantages. It also has a clear disadvantage: size.
Although much bigger, this universal cabinet (I use it for all sorts of stringed instruments) beats the dedicated 15“ steel guitar cab hands down tone-wise. The Eminence driver has turned out a fortunate choice later.
Being encouraged by the excellent results of my build, I now entertain the thought of building a 10“ version, which will be half the size (still big for what you may expect for a 10“ speaker).
Speaker selection utilizing a DAW program:
Choosing a suitable speaker is not easy. Despite the presence of the internet, little can be found for 10“ speakers for steel guitar usage. This format is just not popular. Some people use 12“ speakers, but mostly 15“. Whatever you find, somebody has claimed to have found the best speaker for (pedal) steel guitar, and everybody else seems to repeat this like a mantra.
Of course, being inventive can turn out rather expensive in this place. Trying out drivers will not be available to many. The chance of building a cabinet that turns out a failure plus the wasted cost for a driver will stop most people from even trying.
On paper they all look the same, a little more bass here a little dent there and a litte peak there.
What does this sound like?
Of course, the cabinet will modify the driver´s response to an extent. A too small cabinet will diminish bass response for example. But what would those speakers sound like if they were all built into cabinets „where they feel well“?
Having a DAW (digital audio workstation) on my PC, I went and created a few EQ settings that (hopefully) emulate the responses of a driver. This is easier than you think.
I used the following setup:
* find or create an audio file (.wav) that contains white noise. Audacity can create noise.
* White noise contains all frequencies with equal levels.
* Loop playback this track in your DAW.
* Get a parametric eq plugin (such as the free NCL parametric EQ)
* Get a spectrum analyzer plugin (such as the free Voxengo SPAN)
* link those into the effect chain of the noise signal.
* Adjust the spectrum analyzer until you see about the same amount of decibels on the screen as the graph from the driver datasheet displays.
* Set a LP and a HP filter on the param eq with 12 db/Oct rolloff (that is what speakers do...)
set the frequencies, Q´s (resp. Bandwiths) and gains to complement the driver´s graph.
* Set additional peak filters for notches and peaks
* Use shelve filters for gain steps.
* save this „patch“ with the name of the driver you are emulating.
* Check the decibels for peaks and notches twice, also the octave rolloffs.
* Make a couple of such responses of the drivers of interest.
* Make note of the signal level at one kHz of the „loudest“ driver you have and for all others adjust the overall eq gain so that the response reflects the dB level relative to the loudest. (For example, if you have a -45 db noise signal at 1kHz for the most efficient driver, say 100dB, and some other will have an efficiency number in the datasheet of, say, 98dB, adjust the overall eq gain to -47dB and store that.)
Due to the logarithmic nature of the ear, 3dB changes in loudness are barely audible.
However, you may notice that a speaker model appears louder than another, although it has a lower efficiency figure but has a high peak in a frequency band that the ear is most sensitive at.
Record some piece of
* clean guitar
* distorted guitar
* steel guitar
* bass
* whatever interests you
* remove the noise signal and loop over the other track(s) and cycle through the simulation filters.
* Buy the driver that sounds most appealing 
This will not guarantee that you like the driver inside the enclousure later, but it is a good starting point, if not the only.
By this method I found that the 15“ Eminence that has been much hailed in steel guitar circles, has the same nasty honk that I hated on the speaker I already have. So much for somebody else´s taste...
Some others were not bad.
The SICA speakers (10“ and 15“) all sounded mid-deficient and thus weaker. Not to my taste.
Most of the Eminence Pro drivers (Neo) were not bad, but not the best either.
The 12“ Eminence I already have (Delta Pro 12A) won the contest hands down.
I finally landed with a Faital Pro driver that sounded much similar to the Delta Pro 12A despite the graph that has a lot of ripple.
For fairness, it must be mentioned that such a response cannot be replicated with an EQ, but, as I said, 3dB level difference are hardly noticed.
It was also interesting, that the 10“ speakers did not noticeably lack any bass. I believe that the argument of „15 inch moves more air“ is a) a phrase copied from others and b) irrelevant for high power drivers, as long as you stay within sane levels.
After all, by using this method, I was able to narrow my choice of drivers down to a few. This is a clear advance to before, when I had no clue what to look for.
Have fun,
-helmut
_________________
feel at home at: http://me.aquataur.guru |
|
|
 |
Kerry Johnson
From:
the Bay Area, CA
|
Posted 4 Feb 2013 5:11 pm Faital Pro 12 inch speaker
|
|
Helmut,
Is this the 12" Faital Pro speaker you are referring to?
Thanks
Kerry
Last edited by Kerry Johnson on 6 Feb 2013 12:35 pm; edited 1 time in total |
|
|
|
Helmut Gragger
From:
Austria
|
Posted 5 Feb 2013 6:40 am
|
|
No, its the 10PR300. A 10" Neodyme Bass/Midrange.
They call it the PRO series, although this is meaningless.
A speaker distributor (I think it was the SICA dealer) mentioned, that tags like that turn people off rather than attracting them because they think they cannot use the driver.
-helmut
_________________
feel at home at: http://me.aquataur.guru |
|
|
|
Karlis Abolins
From:
(near) Seattle, WA, USA
|
Posted 5 Feb 2013 6:42 am
|
|
Helmut,
I built a London Power detuned 15 inch cab with a Weber California speaker. The Weber speaker has an aluminum cap. I really loved the cab/speaker combination but the speaker cab was huge. I subsequently built a smaller London Power 10 inch cab with another Weber speaker which has a paper dust cap. It is a much more usable cab because of its size. However, the 10 inch speaker with the paper dust cap lacks a little "sparkle".
I never got an undesirable sound out of the 15 inch cab and I regret getting rid of it. I ultimately built a bass-reflex cab using the 15 inch speaker. the cab is smaller than the London Power design but still too large to take out anywhere.
The original 15 inch cab combined with a London Power-inspired tube amp gave me some of the sweetest sounds I have ever gotten out of my pedal steel.
Karlis |
|
|
|
Helmut Gragger
From:
Austria
|
Posted 5 Feb 2013 7:41 am
|
|
Karlis,
good to hear from other builders.
The 15" detuned will be overwhelming to the point of being unbearable  .
Actually, dependent on the wood the weight is not the main issue, it´s the size.
I am astounded that the smaller speaker lacks sparke, it should extend farer up. Must be your choice of speaker. Weber sounds like a guitar speaker which may not be the best choice for steel due to their usual mid-hump.
I am also building an amp system, inspired by Londonpower, however, I use lateral mosfets.
have fun,
-helmut
_________________
feel at home at: http://me.aquataur.guru |
|
|
|
Karlis Abolins
From:
(near) Seattle, WA, USA
|
Posted 6 Feb 2013 5:54 am
|
|
Helmut,
I think you are right about my choice of speaker in the 10 inch cab. If I get serious about it, I will probably change the speaker.
Karlis |
|
|
|
Helmut Gragger
From:
Austria
|
Posted 15 Mar 2013 1:02 pm
|
|
Karlis,
I think I stumbled over the explanation for this phenomenon. Just finished my 10" enclosure (pics to come) with a driver that on paper should extend beyond a 12" driver.
However, it sounds more mellow. Remembered you instantly.
Just today it dawned on me when I grasped my trusted Strat. On this, I have removed the tone controls and replaced them by two rotary switches that dial a row of progressively increasing small capacitors for treble-cut and bass cut.
This lends the guitar great versatility and a whole new range of tones.
It so happens, that when you have selected the middle range of capacitors that tone all of a sudden starts to sound brighter than with the cap disabled, although the treble range is limited. This stems from the fact that the cap is resonant with the pickup´s voice coil and forms a pretty big hump, that, although the treble range is smaller technically, the hump makes it sound brighter because the tonal balance was shifted.
Same thing must happen on the speakers, where a 12" (or even 15"), although better towards the bass range, may sound brighter than a 10" if it has an upper mid hump that many datasheets expose.
I presume the manufacturers do so exactly for the very purpose.
have fun,
-helmut
_________________
feel at home at: http://me.aquataur.guru |
|
|
|
Helmut Gragger
From:
Austria
|
Posted 4 Aug 2013 9:37 am
|
|
I have finally sewn this into my web pages with pretty self-explanatory piccies and soundfiles.
look down for "Speaker Driver Assessment With Shaped Noise using a DAW"
There are a few samples of all time favourite (not by me anyways ) steel guitar speakers.
have fun,
-helmut
_________________
feel at home at: http://me.aquataur.guru |
|
|
|
