I've been watching this guy's videos recently, I'm not really into the metal music he records and produces (and his f-bombs but whatever), but I find him entertaining. He's talked a lot lately about different models of speakers (all 12-inch "full-range" guitar amp speakers) and their sounds, and maintains the biggest "source of tone" (at least in metal) is the speaker. Rick Beato also did a video on guitar amp speakers - apparently it's common to put different models of drivers in a 4x12 cabinet so you can choose a different driver by putting the mic in front of it.
https://www.youtube.com/channel/UC-f76NUQN5M-Z0cd0MOP5xw
https://www.youtube.com/channel/UC-f76NUQN5M-Z0cd0MOP5xw
Metal music is typically very high distortion, and of a particular type. Generally, amps for metal genres have multiple gain stages, often cascaded, with intermediate volume controls between stages, as well as other tricks to control and shape the tonality and frequency response between gain stages. By the time the guitar signal is compressed and filtered through a very high gain signal chain amp, the tonal differences between amps tend to decrease.
However, guitar speakers are produced in a huge tonal array, on purpose - that permits the player to shape their amp's sound by changing a speaker's frequency response, efficiency, reactance, compression, and so much more. In a very high-gain amplifier/speaker combo, the speaker will generally have a much larger contribution to the overall sound compared to an amp with less gain.
Rick Beato is referring to recording situations, where the microphone and mixing desk, etc. become yet another part of the instrument in the signal chain. Again, this approach to music is intended to produce electronic sounds, and not necessarily reproduce acoustic instruments, although that is also somewhat possible. Having two or four different drivers in a cabinet is a great recording technique to permit a wide range of sounds being recorded, just as when using different mics, preamps, plugins, etc., and it is not unusual for guitar players to use different drivers in their live performance rigs. The favorite cabinet/speaker combo I have is a 2 x 12" open back with two different drivers. Oh, and I should add that only one of my amps is very high gain, and it's not as high-gain as the popular metal-style amps.
However, guitar speakers are produced in a huge tonal array, on purpose - that permits the player to shape their amp's sound by changing a speaker's frequency response, efficiency, reactance, compression, and so much more. In a very high-gain amplifier/speaker combo, the speaker will generally have a much larger contribution to the overall sound compared to an amp with less gain.
Rick Beato is referring to recording situations, where the microphone and mixing desk, etc. become yet another part of the instrument in the signal chain. Again, this approach to music is intended to produce electronic sounds, and not necessarily reproduce acoustic instruments, although that is also somewhat possible. Having two or four different drivers in a cabinet is a great recording technique to permit a wide range of sounds being recorded, just as when using different mics, preamps, plugins, etc., and it is not unusual for guitar players to use different drivers in their live performance rigs. The favorite cabinet/speaker combo I have is a 2 x 12" open back with two different drivers. Oh, and I should add that only one of my amps is very high gain, and it's not as high-gain as the popular metal-style amps.
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@Tubelab_com I’m interested in the relationship between the impedance curve and the speaker response (dBSPL). For example if you take a G10 Greenback
The dBSPL does not have any features near the resonance peak in the impedance.
Why, this is the case is something I have often wondered. What I would expect to see is a reduction in SPL near resonance because the amp is driving a much larger impedance. Would be really interested in your comments!
At the risk of making still more ennemies, I'd say nobody "designs" a guitar amp.
What everybody in the business does is to start with a Fender 3f4 (Bassman) schematic, and tweak from there, for cost, for tone, or both; most well known examples are Marshall, Vox, HiWatt, and so forth. Still more tweaking gets you in the "boutique" zone, the most famous one being the unobtanium Dumble: its schematics are all over the net, and some of them are actually trustworthy; spoiler alert: look closely at its tone stack.
So, my 2 cts: find an old amp, make sure it's a 6L6 push-pull and has point to point wiring inside: PCB are not tweak friendly. Rebuild it to working condition, and start tweaking from there.
What everybody in the business does is to start with a Fender 3f4 (Bassman) schematic, and tweak from there, for cost, for tone, or both; most well known examples are Marshall, Vox, HiWatt, and so forth. Still more tweaking gets you in the "boutique" zone, the most famous one being the unobtanium Dumble: its schematics are all over the net, and some of them are actually trustworthy; spoiler alert: look closely at its tone stack.
So, my 2 cts: find an old amp, make sure it's a 6L6 push-pull and has point to point wiring inside: PCB are not tweak friendly. Rebuild it to working condition, and start tweaking from there.
The original 1952 Bassman was the 5F6-A. It is true that the Marshall JTM45 was essentially a copy of the Bassman circuit of the time, but with changes in parts like tubes, transformers, capacitors, etc.
However, before anyone reading the rather hyperbolic statement above seriously, you can find many, many different approaches to guitar amp design, tube selection, operating points, voltages, filtering, tone stacks, and other features. There are plenty of schematics available for you to verify this.
That Dumble used Fender designs as a launching point, and later in his life pretty much stopped building his own amps and just gutted and modified Fender amps for clients, does not mean they are copies of the Bassman. In fact, many of Fender's own amps are not copies of the Bassman.
Possibly. However, vintage amp prices have really skyrocketed here in the States. It is often much less expensive to start with a known schematic and buy good parts to build an amp from scratch. I have literally hundreds of Marshall variant schematics for various models and modifications by builders. That's what I've done (along with my own interpretations and modifications), since I could never afford to buy 22 vintage amps and modify them, nor would I want to.
Not too long ago, a good way to do as you suggest was to buy old PA amps, pull keyboard organ amps, or film projector amps and modify them into guitar or harmonica (harp) amps. Those donors have become expensive over the past several years.
Not too long ago, a good way to do as you suggest was to buy old PA amps, pull keyboard organ amps, or film projector amps and modify them into guitar or harmonica (harp) amps. Those donors have become expensive over the past several years.
Right: vintage stuff are way over rated, even though I fondly recall standing a few meters away from Brian Setzer playing a '63 brown face Bassman with his Orchestra: it was sonic nirvana!
More realistically, local classified ads may turn up interesting finds: I've just seen a non working Twin Reverb going for CHF350; of course it's way too heavy and too loud, but I still thought long and hard before turning it down. I also found a Champ for free at the local dumpster: not working, required a massive dose of DeOxit. One of my favorite amps is a Selmer Treble & Bass I bought 2nd hand for CHF 250.
More realistically, local classified ads may turn up interesting finds: I've just seen a non working Twin Reverb going for CHF350; of course it's way too heavy and too loud, but I still thought long and hard before turning it down. I also found a Champ for free at the local dumpster: not working, required a massive dose of DeOxit. One of my favorite amps is a Selmer Treble & Bass I bought 2nd hand for CHF 250.
Speakers transform the current of the voice coil into sound pressure but not in all frequencies. Bellow resonance, the current results displacement. At resonance, speed and above EBP, gradually becomes acceleration until the diaphragm breaks up and becomes back speed. Acoustically, frequencies above the frequency fixed by diameter of the diaphragm, 1khz for 30cm, the speed transforms into pressure. Bellow, the acceleration of the diaphragm becomes pressure. The art of designing the diaphragm of open back speaker, is maintain speed to pressure on the whole spectrum.
This is a Grundig radio of high quality with electrostatic tweeters that the speaker is driven in current mode. Look at the break up frequency compensators.
This is a Grundig radio of high quality with electrostatic tweeters that the speaker is driven in current mode. Look at the break up frequency compensators.
There is another way of increasing the presence of the speaker other than horn loaded is parabolic reflector. When the direct radiator was invented, the problem compared to horns was lack of presence, a term introduced by Bell Lab. A French electromechanical engineer Joseph Leon got an idea to load the speaker not on horn but on reflective ellipsoid and founded in 1938 Elllipson. The idea existed beforehand used in last generation of phonograph where the cover made part of the horn.
This is my version of it that makes a 6.5" speaker behave acoustically as 60cm diameter. The driver I made it from a PAudio midrange a longer stroke voice coil and JBL diaphragm keeping the carbon fiber cap. The efficiency is 97db/W/m 6db increase with reflector. Of course the guitar version doesn't need closed enclosure and can be very compact with the reflector replied.
This is my version of it that makes a 6.5" speaker behave acoustically as 60cm diameter. The driver I made it from a PAudio midrange a longer stroke voice coil and JBL diaphragm keeping the carbon fiber cap. The efficiency is 97db/W/m 6db increase with reflector. Of course the guitar version doesn't need closed enclosure and can be very compact with the reflector replied.
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I recall watching the video and saying to myself, 'But what about...". The video does show to what lengths you have to go to do good testing, in part because the author falls short of what has to be done. The architecture is important to how an amp sounds but even with the same design, operating one at 250V or at 450V will alter the sound. Agree with him turning all the controls to 10, but it is easy to test.
- have not yet watched the video but I think a soft screen supply on the outputs can sound different than one that's regulated. My old Traynor YBA3 Custom Special with Hammond output iron sounds "liquid" compared to solid state. Also, operating points of the small tubes and their plate load resistor value may alter harmonics enough to "hear".
That parabolic reflector setup looks really cool - use of one in Karlson's patent 3540544 patent is supposed to reap benefits. I have a "K18" with curved upper panel which measures decently and sounds nice on vocals.
That parabolic reflector setup looks really cool - use of one in Karlson's patent 3540544 patent is supposed to reap benefits. I have a "K18" with curved upper panel which measures decently and sounds nice on vocals.
Had a quite similar experience ages ago.
So what did that teach me?
Hunting for the equipment to find the magic tone - is a waste of time.
You better use this time for practicing.
I see Peavy has Karlson speaker for guitar but only for bass. There must be a reason, I ignor, why not for normal guitar?
Do really guitar amps sound different?
Yes indeed ! Just like for guitars and players...
1/3 for the Player.
1/3 for the Amp.
1/3 for the Guitar.
Remember just that an Audio amp doesn't shares the same sonic qualities as a Guitar amp... These are two different worlds, even if they share many common parts !
You can see some of my builts here, with tone samples : https://guilhemamplification.jimdofree.com/
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If you build amps for sale in more than "boutique" quantities you must use tubes from the list of 8 to 10 tubes that can be bought in a guitar store. There are only so many ways to connect 12AX7's and 6L6GC's, so just about everything involving the list of 8 to 10 has been seen already. There IS some serious innovation being done when the list of 8 to 10 gets augmented with opamps, FETs and transistors. Google up the schematic to something like a Hughes and Kettner Triamp and you will see that somebody still designs guitar amps.
Look up to the top of this forum and you will find the Hundred Buck Amp Challenge. Someone who called himself "tubekit" signed up to this forum with the intention of selling his low buck one tube guitar amp kit. He threw down a line like "You can't build a guitar amp for less than this. Not no way. Not no how," to which I replied "Wanna Bet" and the challenge was the result. Members were asked to design and build a working guitar amp for less than $100. My 4 tube 4 watt amp came in at about $50. Want to see some real guitar amp design and innovation, and some good old copycatting with serious cost reduction, read through the whole thread.......little by little. You WILL learn something.
After the Hundred Buck Amp Challenge ended, I took the little 4 tube 4 watt amp apart and made it into something I liked to play. Part of the redesign involved the infusion of a couple mosfets which were banned in the original design. The other neat trick was to stick a 2.7K ohm resistor in series with the output tube screens and hang the supply to both preamp tubes off the screen side of that resistor. The amp used series string radio tubes that were, and still are available for $1 each and ran from a B+ of about 165 volts. The screens didn't draw much current until the amp started to hit clipping, then the screen current want into glowing grid wire territory with a typical few hundred ohm screen resistor. It took 2.7K to control the glow. Running the preamp from the screen side of that resistor affords a pretty wide range of self limiting power output where the guitar's volume knob, or the strength of the string pluck controlled the distortion leaving the volume relatively constant.
https://images.app.goo.gl/Jwgz26ZTFrFfpgGa8
It is called black widow. I suppose the front volume loads acoustically better than free air but it should get better bass only. The opening will probably by diffraction, increase the radiation angle in consequence, decrease the brightness. It is good for hifi, but is it also for guitar?.
I believe that's the KK Audio version of a Karlson type cabinet produced by a number of small companies: Transylvania Pwer Company, Acoustic Control, Westwood, and a company in Chicago. Its made just like the Acoutic Control 115BK and Acooustic Control BC2 combo other than a rear shelf (whic does not help the response vs 115BK.
The sotry from the Chicago maker: shortly beofer John Karlson died (JAn 1973) he sold, without his wife's knowledege) rights to JBL. After Mr. Karlson passed, Anne sold license to various folks. One was a little company in Chicago. At some point early in production , this man was approched by someone represenitng JBL saying to halt production - or face a lawsuit. JBL never used the patent.
Black Widow is Peavey's line of cast frame woofers - fied serviceable and produced for decades. I wonder if they're still made in the US?
115BK is a smooth playing "Karlson"
The sotry from the Chicago maker: shortly beofer John Karlson died (JAn 1973) he sold, without his wife's knowledege) rights to JBL. After Mr. Karlson passed, Anne sold license to various folks. One was a little company in Chicago. At some point early in production , this man was approched by someone represenitng JBL saying to halt production - or face a lawsuit. JBL never used the patent.
Black Widow is Peavey's line of cast frame woofers - fied serviceable and produced for decades. I wonder if they're still made in the US?
115BK is a smooth playing "Karlson"
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