The Behringer hasnt arrived yet, I'll let you know how it works out weight wise and sound.
Ah, you're forgetting the power supply! All electrically operated things need one (some several, like a computer...) and it's mostly analog engineering. Certainly the level of integration has even included the output inductor itself (Intel...) but someone somewhere has to know what's going on analog wise from the AC / DC input to power supplied.
Let's say the boss says "I want current to be drawn from the whole AC input voltage cycle". What new engineer is going to have some level of understanding for that? It's going to have to be somebody and that would be the kid that took the analog design courses at their university. There will always be room for such an engineer, though perhaps hard to find these days...
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The original Acoustic brand died many decades ago (1970s?). Then, in the early 2000s, someone bought the rights to the brand, and decided to re-launch new Acoustic products.
IIRC, the initial lineup included the AG30, the B20 (20 watt bass practice amp with a 12" speaker), the AB50(?), a wedge monitor for acoustic basses, and a number of larger bass heads, cabs, and combos.
The AG30 and B20 both punched well above their price class, in terms of sound quality. I have one of each.
The AG30 does not have any sort of compressor onboard. It was aimed at the singer/songwriter sort of thing, with two mic/line inputs that could be used for a microphone and an electro-acoustic guitar. It was never intended for electric bass.
The AG30 is basically a wedge-shaped monitor / keyboard amp / small vocal P.A./ acoustic guitar amp, with a nice 8" mid-woofer that includes a post-mounted coaxial plastic (Mylar?) dome tweeter. What struck me right away is that it doesn't have that "boxy" sound common to most similar products, and the treble is even and pleasant to listen to. The sound is pretty close to neutral, with a slight "chestiness" (slight low bass emphasis) which is easily dialed out.
To my ears, the AG30 sounded as good as similar Roland wedge-shaped keyboard amplifiers, but at half the price. It was a very easy shopping decision to buy one!
(I bought a second one later, and used to use both at jams - one facing the room, the other facing back at us, as a monitor. I left the second one behind when I moved from L.A. to BC. I still miss it, eight years later.)
Unfortunately, the timing behind the relaunch of the Acoustic brand could not have been worse. Acoustic relaunched right around the time of the Great Recession of 2008. The next five years were very difficult years for any US consumer electronics company to survive.
I believe Guitar Center took over the brand, and made the Acoustic line-up one of their house brands.
-Gnobuddy
I have been reading Merlin Blencowe's book Designing High Fidelity Valve Preamps, and also came across an article posted in 2021 on Elliot Sound Products website: Designing with JFETS. One of the comments that often comes up is the variability of JFET parameters, and although this is indeed the reality, as well as a decrease in the availability of JFETs intended for audio/linear use, there are also a lot of points to consider regarding variability of valves. For the most part there are well established circuit designs for common valve preamps using "standard valves", and they are more plug and play..they work well within a well designed circuit, but designing from scratch with a different valve involves much the same considerations. The same can be said for BJT designs. What I find compelling about JFETs as amplifying stages is distortion increasing gradually (low order harmonics) with increasing signal amplitudes. With soft limiting on a couple of CS stages, that effect can be enhanced. I used a diode (with series/parallel resistance) in inverting negative feedback from drain to gate. This squishes half of the signal cycle at the stage output. The gate is now a virtual ground for AC signals, and I put a series resistance at the input of the signal path..whether it absolutely needs to be there is debatable. Will try and take some time to build out a more complete "no op-amp" preamp circuit soon.
I saw an Ibanez TSA-15H amp for sale on line and was considering it, as it has a pair of 6V6 on the outputs, 12AX7 driving. I managed to land the schematic and - yeah - it does have those with a typical tone stack between the 'AX7 stages, but also what looks like a "tube screamer" circuit upstream made, you guessed it, out of op-amps. Back to back diodes in the feedback of the 2nd op-amp.
Lost interest after seeing the schematic. Which poses in interesting question for the engineering types; how many times have you "lost interest after seeing the schematic"? In any piece of audio gear?
Lost interest after seeing the schematic. Which poses in interesting question for the engineering types; how many times have you "lost interest after seeing the schematic"? In any piece of audio gear?
You are missing the point here, big time 😉
The built-in TS is a feature here, they charge extra for it, and it is even mentioned in the amp name (guess where the "TS" bit comes from).
And OF COURSE it is made out of "Op Amps", has "clipping diodes", etc .... what else would you expect in a 9V battery fed Guitar Pedal?
One of the most successful by the way, and used by some of the best Guitar Players.
Not surprised at some DIYA Forum member "listening with his eyes" by the way 😉
Here, a TS pushing a Fender amp:
from: https://happybluesman.com/how-sound-like-stevie-ray-vaughan/
Well. I wonder if either of those two diodes were conducting any when he did the behind the back thing? A nice watch - thanks - I almost finished a documentary on him just last night.
I guess you cant argue with success. I've seen that diode arrangement driven in all tube circuits, and I can understand why Ibanez didnt architect it using all tubes when, they already have something that cant be beat and it's then just a matter of connecting half A to half B.
The closest I've ever come to a song like that was me playing bass and some other guy on guitar. In all actuality, especially these days, I'd have no use for a TSA-15H anyway, which is the practical reason why I didnt buy it. But admittedly, the discussion here did have an influence - enough for me to check out the schema and see what made it tick. And then go "yecch" - perhaps an inappropriate response.
So considering it's perhaps the most played circuit in the world, by people light years beyond what any of us here might ever achieve in terms of performance tone, is the notion of "Oh my God - an op-amp at the input!" something that's just...ridiculous? As in, as you say, "listening with your eyes"?
I guess you cant argue with success. I've seen that diode arrangement driven in all tube circuits, and I can understand why Ibanez didnt architect it using all tubes when, they already have something that cant be beat and it's then just a matter of connecting half A to half B.
The closest I've ever come to a song like that was me playing bass and some other guy on guitar. In all actuality, especially these days, I'd have no use for a TSA-15H anyway, which is the practical reason why I didnt buy it. But admittedly, the discussion here did have an influence - enough for me to check out the schema and see what made it tick. And then go "yecch" - perhaps an inappropriate response.
So considering it's perhaps the most played circuit in the world, by people light years beyond what any of us here might ever achieve in terms of performance tone, is the notion of "Oh my God - an op-amp at the input!" something that's just...ridiculous? As in, as you say, "listening with your eyes"?
Indeed, it is very effective at both overdriving a tube amp, and adding harmonic distortion in a complementary way. Plus you get some EQ shaping that boosts mid/high frequencies, which does a nice job of thickening the sound and filling in some of the mid-range dip present in a lot of Fender and Marshall type amps. Some people don't like the "mid-hump" response, but I think that is more a matter of "modern" tastes and progression of styles.
Wouldn´t be so harsh as to use the word "ridiculous" (I reserve that for fanatically praised snake oil ideas) but:
1) Op Amps are the most useful gain block on Earth and do almost anything (including many "tube things") as long as:
2) they can swing between +/-15V rails,
3) you are clever enough to design the proper FB net.
4) and I mean almost anything: asymmetrical clipping, rounded peaks, bias shifting, gain variation/compression, duty cycle modulation, even humming-popcorn_noise-hiss-buzz
As of "listening with your eyes" ... you said so yourself !!!!!
😉
In 1979, you would expect exactly that - clipping diodes and an op-amp. The resulting sound was very nasty, only becoming tolerable if you fed it into a tube amp to remove the nastiness. Add delay and/or reverb or modulation as well, and then you could turn that nasty sound into long singing violin-like sounds.
The pedal sounds nasty on its own. (Unless you're one of the people who like the sound of fuzz-boxes.)
Ibanez was even forced to use worse-sounding symmetrical clipping because Roland/Boss already had a patent on better-sounding asymmetrical clipping that they were using in some of their own OD pedals.
Today, we can do much, much, much better than op-amps and clipping diodes:
Notice that THERE IS NO TUBE AMP in Kingman's demo of the Flamma Preamp. What you're hearing is entirely inside a 9V guitar pedal, nothing more, except for the parts of the video where Kingman variously adds delay and/or an external overdrive pedal - yes, a Tube Screamer!
This pedal does not sound nasty on its own.
And that is exactly the key: the tube amp that follows the TS "sandpapers off" the harsh edges from the TS, leaving you with a musically usable sound. Let's not forget the delay and reverb from the large venue.
Eager young guitarists who wanted to emulate their wealthy guitar heroes tried running a solid-state tube screamer direct into a solid-state guitar amp in the bedroom. The resulting sound is often described as "a wasp in a jam-jar". Harsh, buzzy, unpleasant.
Anyone want to find and listen to a video of a Tube Screamer feeding directly into a powerful clean solid-state P.A system?
No? I didnt think so. That sounds like a swarm of 100-cc dirtbikes at full throttle, mixed with the sound of ten million angry wasps in a jam jar. Harsh, unpleasant, nasty, painful to listen to.
As Shanx said, the other key to the TS was EQ. It helped compensate for the midrange dip in classic Fender amps. Sucking out the midrange was Leo Fender's recipe for shimmering clean tones, but that same EQ curve works poorly for single-note rock/blues solos. For that, you need some sort of midrange peak, and both the TS and the Klon provided it.
Yes, op-amps are extremely versatile, and can do everything from precisely calculating definite integrals of mathematical functions, to providing precise signal conditioning inside medical electronics. They are an absolutely amazing invention, and have reached a level of perfection that makes them one of the huge shining stars of contemporary analogue electronics. They have thousands of applications where they are the perfect solution to a engineering problem. No sane and well-informed person would say otherwise.
But if you simply whack a couple of feedback resistors around an op-amp, set it for even a relatively small voltage gain (+20 dB), power it from 9V, and feed it a raw e-guitar signal, it will clip harshly for a big part of each note.
Raising the power supply voltage to +/- 15V may keep that first stage from clipping harshly, but it only transfers the problem on to subsequent stages of the amplification chain. If one or more of those stages is a tube amp that overloads gracefully, you can end up with good sound. If those later stages are just bigger and badder op-amps (all modern solid-state audio amps are just bigger op-amps), then the harsh clipping problem will simply occur in the power amp instead of the preamp.
I proved, quite clearly, in a recent thread, that this problem exists. I've been hearing ugly gritty harsh clipping from solid-state guitar amps for decades, though I didn't know exactly what I was hearing, or why it occurred. Only recently, I finally figured out exactly what I was hearing. Now I've provided the explanation, along with objective evidence. There is no longer reasonable room for doubt.
For some of us, that sort of harsh op-amp clipping is a very unpleasant sound.
Musical tastes vary widely, and I'm sure that somewhere, there is a guitarist who loves the sound of harsh clipping, and she/he may even have an audience that enjoys that sound. All good wishes to them, but it is not a sound I ever want to hear.
Are there ways to tame the harsh clipping inherent to high-NFB amplifier stages? That is a perfectly valid question, and well worth exploring. It is already being explored on other current threads on this forum.
But simply whacking standard high-NFB non-inverting or inverting op-amp preamp blocks, followed by a high-NFB power amplifier, will produce the sort of gritty clipping sounds that sound so very unpleasant to me (and to many, many other guitarists).
To avoid that, you need stages that overload gracefully, without harsh clipping, somewhere in the chain between guitar pickup and speaker. Doesn't matter how you accomplish that - whether you use tubes, JFETs, BJTs, or eye-of-newt-and-toe-of-frog. As long as you find a way to create graceful, gradual, progressive, soft clipping, there is a good chance at success.
-Gnobuddy
How does a tube amp removes nastiness? Assuming it is the transit you are so sensitive to how does the tube amp alter the first offending mS of harshness when the peak is gone? With a Tubescreamer (for example) the clipping diodes chop off the offending peaks before the second stage overloads so you can not blame the second IC stage for the harshness.
I have no idea. But I can hear that it does.
It's not a subtle effect, either. Stevie Ray Vaughn and other many other blues guitarists of his time could have run their Tube Screamer straight into a solid-stage rack-mount transistor guitar amplifier if they wanted. None of them ever did, because that combination sounds absolutely disgusting.
Same story with delay. How does delay after a Tube Screamer or, even worse, a Fuzz-Face, remove that horrible harshness? No idea, but it is very easy to hear that it does. There is probably a complicated mathematical convolution function that would explain why.
Same story with reverb after clipping, either alone, or in conjunction with delay. Reverb removes the harshness. Is this an actual electrical effect in the signal? Or does it happen in the listeners ear/brain? I have no idea. But there's no doubt that reverb after distortion reduces audible harshness.
The whole story with those horrible-sounding 1980's rack-mount SS guitar preamps and power amps is fascinating. They sounded atrociously bad, and after a few years of being brain-washed into using them, most guitarists realized this, and went back to using the older generation of tube amps.
But the SS guitar FX pedals remained. As long as you used them along with a tube amp, you could produce good sounds.
I've tried good FX pedals (like the Boss Blues Driver) into small SS (not tube) guitar amps. The combination sounded absolutely vile.
For me, FX pedal into SS guitar amp has always sounded vile, for the past several decades. That's finally changed with the Flamma Preamp. I can run my EHX Soul Food Overdrive into the input of the Flamma Preamp, and get good sounds out of the pair. The Flamma Preamp works the same sort of magic as a good tube amp, removing some of the audible harshness from the Soul Food.
How? I have no idea.
It took me from roughly 1985 to 2022 to finally understand why I was hearing that gritty harshness in the "clean tone" of solid-state guitar amps.
I am unlikely to live another 37 years. I may never figure out how a tube guitar amp removes audible harshness from a harsh-sounding Tube Screamer or other distortion box.
I will keep thinking about it, though. 🙂
-Gnobuddy
A clipping Tube amp removes nastyness, by re-clipping the nasty edges off.
Plus other things such as increasing Bass at resonance because of poor damping, using a brutally frequency limited speaker (24 dB/oct above 2.5kHz 😱 ), inroducing assymmetry where there was none, etc.
Tube amps are "sound processors" which as a secondary job drive speakers 😉
I laugh when people talk of Fender sound as "Fender Clean" 😉
Seeing that these distortion pedals came about due to non-master amps being too loud to overdrive then the effect is due to the single triode stage before the volume control (Fender, gain stage - tonestack - gain stage). So maybe only one triode is all that is needed?
I think you could, if you drive that input triode stage, and then there`s the tone stack. If it`s a Tweed Type they are less lossy than the Black Face era TMB stack. So the recovery triode gain stage after will be driven more or less, depending on that stack. I did a three stage JFET-JFET-MOSFET preamp with only volume control after the 1st stage, with no tone stack just a master volume out.. that can get into some heavy overdrive sounds! But it`s a progressive type of distortion that does respond well dynamically, lowering the input volume cleaned up the signal, to almost clean-ish.
Well that's weird. I posted a reply last nigh, pushed the "Post reply" button - I swear I saw it here and this morning, poof - gone! Let's try that one again (in Daffy Duck voice)
I had a circuit, some 40 years ago, built using a transistor array chip, something like a CA3018, that supposedly implemented this;
I was interested in it at the time because the "design note" or whatever I had copied at work then showed an oscilloscope trace with really rounded tops on a squarish looking waveform. Versus the cleanly cleaved-off head and tail of a diode clipper. Unfortunately, I never built it, so I cant say how it sounds as the distorting / harmonic generating element in a signal chain with a guitar as input.
The piece of paper may be floating around in my files somewhere. It used to have the IC taped to it, but that's as far as it ever went with me at the helm. If I find it, I'll post it here.
I had a circuit, some 40 years ago, built using a transistor array chip, something like a CA3018, that supposedly implemented this;
I was interested in it at the time because the "design note" or whatever I had copied at work then showed an oscilloscope trace with really rounded tops on a squarish looking waveform. Versus the cleanly cleaved-off head and tail of a diode clipper. Unfortunately, I never built it, so I cant say how it sounds as the distorting / harmonic generating element in a signal chain with a guitar as input.
The piece of paper may be floating around in my files somewhere. It used to have the IC taped to it, but that's as far as it ever went with me at the helm. If I find it, I'll post it here.
Sorry but you got it the exact opposite way.
These pedals came to FURTHER overdrive amplifiers NOT designed to do so (even Rose Morris Marshall ads bragged about the loud distortionless sound ) which barelyclipped with then curent pickups.
From: https://www.vintageguitarandbass.com/adDetails/488
>>>>>>>>>>>>>>>>>>>>>>>
Marshall advertisement (1967)
The Sound of Success
Marshall Amplifiers
Rose-Morris Marshall advertisement from late summer 1967 (September / October). This advert shows a number of acts that use Marshall equipment: Roy Orbison and the Small Faces (who had been on tour together in the UK earlier in 1967), the Jimi Hendrix Experience, and the Who.
Rose Morris had included images of Rickenbackers in the majority of Marshall advertising through 1967, but their relationship was coming to an end. Pete Townsend is pictured here, with a Rickenbacker, but this montage would be recomposed, replacing them with Procul Harum on a similar advert placed between November 1967 and January 1968.
Marshall's solid sound is behind all these great groups. Marshall world's most powerful, distortion-free amplification equipment. 😱 Put Marshall behind you! Select your own particular set-up; over three dozen separate units 18 watts to 200 watts.
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
No Di Marzio super distortion pickups way back then, current amps matched current (weak by today´s standards) pickups, Strats and Teles could not do so unaided, only ones who could were Humbuckers hence tbe popularity of Les Pauls, and Jimi Hendrix HAD to resort to a nasty fuzz to do his thing.
Even DEric Clapton and Ritchie Blackmore cheated, all used Dallas Arbiter German ium Boosters in their setups, without even mentioning ghem.
I co me from thatb era, and remember pMusicians im prting a Strat or LP and "A Marshall" at great expense .... and NOT havin g the sound they expected, by far.
I personally saw one of our great Guitar players , Hector Starc, throw a Strat against a wall, in frustration, (greatly damaging it) , because "the d*mn thing would not sustain/overdrive even with all amp knobs on 10", and borrow a LP from a fellow Musician .
Gibsons were as rare as hen´s teeth because being of solid construction they could not be easily bootlegged into Argentina (a guitar case advertised to the World you were bringing one in), while bolt-on neck Strats were plentiful, because you could unbolt it and hide the whole guitar inside a regular "clothes" suitcase.
Hector Starc was envied because he had TWO Fender amps, a Bandmaster and a Dual Showman, both always used "on 10" of course, and his secret weapon was a Standel rack preamp, used to boost them to death.
The preamp being very clean and SS of course.
Amps were not "too loud to overdrive" ; on the contrary, were "too weak to be heard", so they were used "on 10" all the time, and since that was not enough, "wall of amps" had to be built up.
Remember: NO PA (by today´s standards), HUGE venues, thousands to tens of thousands people.
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I think it is in the other thread.
Discussion: Unwanted clipping in solid-state e-guitar preamps
https://www.diyaudio.com/community/...id-state-e-guitar-preamps.391513/post-7204675
Yes, the 70's were a time when we used stage amps to fill the room with sound (been there, done that). In the 80's with better PA's (tube screamer introduced in '79) people were using the pedals more for distortion than just to goose the amps. At least around here that was the case.