Anybody point me in the direction of a SS guitar amp kit? Preferably with step by step guide.
Thanks in advance 🙂👍
Thanks in advance 🙂👍
Moved to Instruments and AmpsNot a kit - but rather close:
I've build my own version of Rod Elliots 100W guitar amp (https://sound-au.com project #27) for my son, and he was quite happy with it.
It can be scaled down by using a smaller transformator or by just using an 8 Ohm speaker (currently I have 25W with a Celestion A-type 12" speaker).
You can get the PCBs from Rod E - and then it is "just" a matter of getting the components. The description with the project is semi-detailed - but have a look for yourself.
Cheers, Martin
What sort of guitar? Electro-acoustic (sometimes just called "acoustic" in North America), or electric?
What sort of amp? A little toy one for living-room use? A big loud one that will make you a social pariah and set tongues wagging in the village/housing complex?
Since thoglette suggested a little toy amp: Digikey sells a nice little LM386 amp already built on a little PCB, ready to go: https://www.digikey.com/en/products/detail/dfrobot/DFR0064/6588477
It can be powered by an old USB charger (5V DC), or a 9V flat battery, or any small DC power supply up to 12 VDC, say, 9 V.
By itself, the board has no volume or tone controls, and will have the typical "too clean until it suddenly becomes too dirty" characteristic when you plug a guitar in. It may also have an input impedance that's a little too low to be ideal for an electric guitar. But it might work well with an electro-acoustic guitar, which has its own onboard tone controls and preamp.
If you want to use this with an electric guitar, you can easily add a simple preamp in front of it to sweeten the clean tones a little bit. A single JFET is a good start; try using it configured as a Fetzer Valve http://www.runoffgroove.com/fetzervalve.html ).
I would suggest using a 10k trimpot for Rd, rather than a 50k one. 50k is really too large, and will end up set to nearly one extreme. A 10k trimpot will be less "twitchy" to set.
This still has no tone controls, and will sound midrange-dominant and dull until overdriven. If that's not to your taste, Runoff Groove has several other (more complex) JFET-based circuits that you can place ahead of the Digikey LM386 board.
The J201 FET or MPF 102 FETs used in some of these old circuits may not be available any longer. If this idea appeals to you, we can help you find a JFET that is still available, and which will work in this circuit.
-Gnobuddy
What sort of amp? A little toy one for living-room use? A big loud one that will make you a social pariah and set tongues wagging in the village/housing complex?
Since thoglette suggested a little toy amp: Digikey sells a nice little LM386 amp already built on a little PCB, ready to go: https://www.digikey.com/en/products/detail/dfrobot/DFR0064/6588477
It can be powered by an old USB charger (5V DC), or a 9V flat battery, or any small DC power supply up to 12 VDC, say, 9 V.
By itself, the board has no volume or tone controls, and will have the typical "too clean until it suddenly becomes too dirty" characteristic when you plug a guitar in. It may also have an input impedance that's a little too low to be ideal for an electric guitar. But it might work well with an electro-acoustic guitar, which has its own onboard tone controls and preamp.
If you want to use this with an electric guitar, you can easily add a simple preamp in front of it to sweeten the clean tones a little bit. A single JFET is a good start; try using it configured as a Fetzer Valve http://www.runoffgroove.com/fetzervalve.html ).
I would suggest using a 10k trimpot for Rd, rather than a 50k one. 50k is really too large, and will end up set to nearly one extreme. A 10k trimpot will be less "twitchy" to set.
This still has no tone controls, and will sound midrange-dominant and dull until overdriven. If that's not to your taste, Runoff Groove has several other (more complex) JFET-based circuits that you can place ahead of the Digikey LM386 board.
The J201 FET or MPF 102 FETs used in some of these old circuits may not be available any longer. If this idea appeals to you, we can help you find a JFET that is still available, and which will work in this circuit.
-Gnobuddy
Attachments
Please define your needs a little better.
No big deal about the power amp, any size available, its power supply, etc. ; the problem will be a dedicated Guitar Preamp.
Some pedals approach such functions, but are generally designed to be plugged into an existing preamp, so ...
Rodd Elliott offers many power amps but one Guitar preamp; if you can get the boards from him you can save on postage by ordering all at once in the same package.
Some ideas:
1) Rod Elliot´s, only current full and well documented SS Guitar Pre and Power Amp, read it a few times at least to have an idea of what you need:
https://sound-au.com/project27.htm
2) same basic structure as above, but using a "preamp style" guitar pedal.
Marshall Guv´nor and is descendants are basically "a Marshall SS preamp inside a pedal" and can straight drive a generic SS power amp.
One of many pages describing them.
Uses strip/vero board so it´s easier to build at home.
Drive any small/medium power amp from it, say abTDA2030/LM1875 one for a typical home practice amp, or anything larger.
http://tagboardeffects.blogspot.com/2012/12/marshall-guvnor.html
At most need some tweaking to raise output level from typical 100-200 mV to about 1V, which is doable.
Guess some PCB (or Veroboard) layouts are available at the Guitar Pedal sites.
Much better than the crude FET "Tube Amp emulators"
No big deal about the power amp, any size available, its power supply, etc. ; the problem will be a dedicated Guitar Preamp.
Some pedals approach such functions, but are generally designed to be plugged into an existing preamp, so ...
Rodd Elliott offers many power amps but one Guitar preamp; if you can get the boards from him you can save on postage by ordering all at once in the same package.
Some ideas:
1) Rod Elliot´s, only current full and well documented SS Guitar Pre and Power Amp, read it a few times at least to have an idea of what you need:
https://sound-au.com/project27.htm
2) same basic structure as above, but using a "preamp style" guitar pedal.
Marshall Guv´nor and is descendants are basically "a Marshall SS preamp inside a pedal" and can straight drive a generic SS power amp.
One of many pages describing them.
Uses strip/vero board so it´s easier to build at home.
Drive any small/medium power amp from it, say abTDA2030/LM1875 one for a typical home practice amp, or anything larger.
http://tagboardeffects.blogspot.com/2012/12/marshall-guvnor.html
At most need some tweaking to raise output level from typical 100-200 mV to about 1V, which is doable.
Guess some PCB (or Veroboard) layouts are available at the Guitar Pedal sites.
Much better than the crude FET "Tube Amp emulators"
This one (Flamma Preamp) is very hard to beat in terms of bang for the buck.
Honestly, even if you set price-point considerations entirely aside, the sound quality is excellent by any reasonable standard; the only trouble is, there's nothing left to DIY!
The Flamma Preamp goes for an almost unbelievable $76 USD: https://www.amazon.com/FLAMMA-Digit...le/dp/B08LMLRQ44/ref=sr_1_2?crid=ATQ805D62NET
Everything, from very good amp simulations to speaker cab simulation, is already inside the Preamp. All you have to do is run your guitar into it, and run its output to a flat frequency response powered speaker (or a headphone amp).
You get 14 different simulations - models of 7 different famous tube guitar amps, each one with a clean and a dirty channel, for a total of 14 distinct sounds. Want an instantly recognizable Fender clean tone? Model 1 on the clean setting has what you want.
This is the kind of versatility that you really can't get out of an analogue guitar preamp, whether "toob" or solid-state. Digital modelling does it easily, but until just a few years ago, every digital guitar modelling device I heard sounded like garbage, at least until you got well above the $1000 USD price point.
But, at least to my ears, that has changed dramatically in just the last year or two. The Flamma Preamp is the most striking example I know of.
Since the Preamp's output is an instrument-level audio signal, you can run its output into any favourite guitar FX pedals you own. This lets you easily do things like have reverb and delay after the (Preamp) distortion, which are otherwise impossible with a real guitar amplifier except in studio situations. (You can't run the speaker-level output of a guitar amp through your Hall Of Fame reverb pedal.)
Of course you can also put any of your FX pedals at the input of the Preamp, as you normally do with any real guitar amp.
In the Covid era, loud amplifiers are completely out of the question for those who, like me, live in apartments. So my living room guitar setup is now based around a Flamma Preamp, a couple of other guitar pedals, a home-made headphone amplifier, a pair of small mini-Hi-Fi speakers rescued from a thrift store, and a little Lepai class-D power amp. If the TV is off, I play through the Lepai and speakers; if the TV is on, or it's late at night, or I just want a bit more SPL at my ears, I use the headphones.
-Gnobuddy
He´ll find this ... I guess 🙂
Not sure what an OP sees when logging in, guess he gets a reminder or something.
A Moderator might tell.
EDIT: nice preamp.
In any case, there siill is a lot to diy: a power amp, its power supply and the speaker cabinet, which in trye Guitar amp combo tradition, should be "all together" with a handle on top he he.
Suggestion:for home/garage use in Covid times, one solution could be a 15W amp (TDA2030/LM1874 based) with its own power supply or a similar Class D one fed from an old laptop brick , driving a guitar 6/8/10" speaker (suggestions below) which is a most important part of sound, forget Hi Fi speakers, all inside a small wooden cabinet, you can even buy one of those cheap grey carpet covered (or uncovered, just paint them black) "car speaker" cabinets, dirt chep, and mount electronics and speaker inside.
Don´t forget the top handle 😉
It may end up looking similar to this :
Not sure what an OP sees when logging in, guess he gets a reminder or something.
A Moderator might tell.
EDIT: nice preamp.
In any case, there siill is a lot to diy: a power amp, its power supply and the speaker cabinet, which in trye Guitar amp combo tradition, should be "all together" with a handle on top he he.
Suggestion:for home/garage use in Covid times, one solution could be a 15W amp (TDA2030/LM1874 based) with its own power supply or a similar Class D one fed from an old laptop brick , driving a guitar 6/8/10" speaker (suggestions below) which is a most important part of sound, forget Hi Fi speakers, all inside a small wooden cabinet, you can even buy one of those cheap grey carpet covered (or uncovered, just paint them black) "car speaker" cabinets, dirt chep, and mount electronics and speaker inside.
Don´t forget the top handle 😉
It may end up looking similar to this :
Last edited:
TDA2030/LM1875 is a great chip amp for a portable combo. With a good guitar speaker these things can get pretty loud. You can use the preamp's output level as a master volume though and dial it down to really low level for home use.
Particularly for a portable guitar application, I think there are overwhelming advantages to using a contemporary class D amplifier board, rather than an much older class B design (popularly but rather incorrectly referred to as class AB).
A class D amp is more efficient, runs cooler, is lighter (tiny heatsink), and costs less per watt.
But the fact of the matter is that we have no idea what the OP actually wants...or wanted, nearly two weeks ago.
-Gnobuddy
True a Class D amp may be the way to go, you could fit those boards into a pedal enclosure too. I haven't played around with them but
saw a few TPA3118 based modules that are really tiny. Maybe one day I'll wire one up and see how it compares.
saw a few TPA3118 based modules that are really tiny. Maybe one day I'll wire one up and see how it compares.
Rod Elliot's designs appear to be great. Anyway, in the preamp I'd put a 1 MΩ resistor across the Bright switch.
Best regards!
Best regards!
...with the usual proviso that it will sound like every other high-NFB solid-state guitar amp: clean tones will be too clean, sounding thin and cold when you play an electric guitar through it.
My experience is that this sort of Hi-Fi clean preamp works well for electro-acoustic guitars, acceptably for hollow-body archtop electric guitars in a jazz context, tolerably for semi-hollow electric guitars (like the ES-335), and very poorly for solid-body electric guitars ('Strats, Les Pauls, etc).
Too-clean is not the only problem with this type of SS guitar preamp, built around op-amps and textbook Hi-Fi building blocks. Elliot claims his low-impedance diode clipper (D2/D4/R14, here: https://sound-au.com/project215-p27-revisit.htm) will distort less harshly than more common higher impedance versions of similar circuits. That may be true, but only a mother, ahem, Hi-Fi audio engineer, could love the raw sound of an electric guitar fed through two reverse-parallel clipping diodes.
Physicist John Murphy figured out, decades ago, that for overdriven guitar to sound good, the duty cycle of the output waveform needs to vary with signal amplitude. This happens automatically with vintage capacitor-coupled guitar amplifier designs, as average bias current through the various gain stages unintentionally shifts with input signal level, due to the nonlinearities in the amplifying device.
However, duty cycle modulation doesn't occur at all with textbook op-amp gain stages, or the sort of anti-parallel clipping diode approach Elliot uses in his preamps. Instead you get a predictable and perfectly symmetric output waveform, which sounds like a predictable and boring buzz.
John Murphy designed an op-amp circuit that created duty cycle modulation when overdriven, by using a small-signal diode to deliberately shift the op-amp operating point dynamically with signal level. That circuit was used in a number of Carving solid-state guitar amps over the years.
I found sound clips of some of those old SS Carvin amps on the 'Web a few years ago. To my ears, guitar clean tones were thin, sterile,cold, and unpleasant, just like every other op-amp based electric guitar preamp. But overdriven tones were definitely richer and better sounding than the generic diode-clipper circuits we've all been listening to for years. Murphy was definitely on to something.
I think a combination of a JFET stage (or stages) to add a little low-order harmonic distortion to warm up the cold clean tones, and John Murphy's duty-cycle-modulating op-amp distortion stages, might be very interesting to try. Perhaps that will finally produce an analogue SS guitar preamp that actually sounds halfway decent.
Then again, you could simply plunk down $76 (USD) and buy the remarkably good-sounding Flamma Preamp discussed above. 🙂
This old (1994) article about John Murphy makes interesting reading: https://www.trueaudio.com/at_eetjlm.htm
-Gnobuddy
There is this Russian guy who went very far with jfet triode emulation, here is a thread on the solid state guitar amp forum. Very impressive.
Or a Flamma Preamp. 😀
Seriously, I spent many years of wasted effort building solid-state electric guitar amps (because I was a starving student with no money to buy a known good guitar amp). Every single one I built sounded awful. It was incredibly frustrating.
As it turned out, I had what turned out to be a very unfortunate combination - a brain that knew a lot about solid-state Hi-Fi audio design, along with a musician's ears.
I did not know that Hi-Fi audio circuits sound awful with electric guitars, and that is why every one of my attempts produced bad sound. Even less did I know that only a bad amplifier sounds good with electric guitar - but it has to be "bad" in just the right way!
Valves were obsolete before I was born, and I had never even seen one, though I had been building electronic circuits since about age eight. So I never paid any attention to valve (tube) guitar amps - why waste my time and energy on ancient, obsolete technology?
As it happened, I also taught myself how to play guitar in isolation, with no musical buddies who knew better than me, so there was nobody to tell me how wrong I was about valves. I remained ignorant for a long, long time.
After two decades of bad guitar tone, discouraged and at the brink of giving up electric guitar for good, I finally tried my first tube guitar amp. The first strum of a simple chord was a jaw-dropping revelation. THAT was the sound I had been missing all those years!
You may believe that "only tubes will do" is nothing more than a silly superstition. But I heard a dramatic difference, right away. And I wasn't favourably biased - I came to tube amps with the negative preconception that building with old, obsolete, glorified light-bulbs from the dawn of audio electronics a century ago, made no sense at all. My very first Fender tube (hybrid) amp, a Super Champ XD, converted me at the first strum.
The simple truth is that a very simple DIY tube guitar amp will generally sound much better than even a much more complicated analogue DIY SS guitar amp. Throw together a couple of 12AX7s and a 6V6, and, if you have a good pair of ears, it will sound much better than Rod Elliott's quad-opamp, 14-discrete-transistor, juggernaut.
For decades, you also had another route to horrid SS guitar sound: there were plenty of affordable DSP-based digital guitar preamps / multiFX units out there, all of them uniformly horrid-sounding. Line 6 started making nasty-sounding DSP amps in the mid 1990s, and by 2010, they had lots of equally nasty-sounding competitors. I should know, I was dumb enough to buy several of them, only to be frustrated by bad guitar tone and rapid ear-fatigue every time.
But Moore's Law continued to hold for DSP chips, and DSP processing power per dollar continued to climb rapidly. Somewhere along the way, DSP chips became powerful enough to run good-sounding tube amp models in digital modelling preamps - but it would cost you at least $1000 USD to buy one of them. Kempers, Axe-FXs, and AmpliFIREs sounded good, but you could still buy a real Fender tube amp for less.
All that changed Just in the last year or so. At least according to my ears, we passed a watershed moment: really good-sounding, DSP-based digital guitar modelling preamps, at very affordable price-points, arrived for the first time. The Fender Mustang Micro ($100 USD initially), and the Flamma Preamp ($76 USD) are both spectacularly good IMO.
I heard about the Mustang Micro first, before I became aware of the Flamma Preamp, via this excellent Cosmo Music demo:
Personally, I loathe the "plug straight into your guitar" design of the Mustang Micro, which invariably manages to put the control you want where you can't see it. If your guitar has its output jack on the edge of the body, as most do, your Mustang Micro is in danger of being broken any time you set your guitar down on a music-stand. But there is no arguing with the quality of the onboard amp models and sound effects.
So there you go. I don't like SS amps like Rod Elliott's design, because I know from long experience that this type of SS amp invariably sounds lousy to me. But I don't blindly insist on "toobs", either - just on a good-sounding amp, no matter what technology was inside. If you got great sound out of an affordable box full of pigeon-feathers, beeswax, and rusty nails, I would gladly buy and use it.
The pigeon-feather amp isn't here yet, but today, digital technology has made it possible for a $76 DSP preamp to sound about as good as a large box full of tubes, and better than some. Fantastic!
-Gnobuddy
Thank you for the reminder! I'm familiar with KMG's work. And I agree, it's very impressive!
While KMG did a fantastic job of getting a single LND150 MOSFET to sound like one of the triodes in a 12AX7, I found out that he did overlook one detail. On the breadboard, when you load the output of one of KMG's MOSFET stages, the output voltage falls far more dramatically than a real vacuum triode.
In other words, the output impedance of his MOSFET gain stage is much too high.
A little thought revealed the source of the discrepancy.
A real 12AX7 stage with a 100k anode resistor has an output resistance of around 40 kilo ohms, because the tube's own anode resistance (plate resistance in America) of roughly 70 k appears in parallel with the 100k external anode resistor.
The little MOSFETs KMG used, however, have a much higher output resistance - the Id/Vd curves are very nearly horizontal, unlike the sloping Ia/Va curves of a vacuum triode.
As a result, the output impedance of one of KMG's MOSFET gain stages is closer to 100k than to 40k. There is no 70k anode resistance to parallel the 100k resistor, and make it appear to be only 40k. So the output resistance is much too high.
I think this could be fixed with some experimentation. Replace the 100k drain load in a KMG gain stage with a 39k resistor. Now tweak the KMG combination of diodes and resistors connected to the MOSFET source, to get back the voltage gain and distortion characteristics of a half-12AX7. It will mean lowering the unbypassed source resistance, and maybe also reducing the number of Schottky diodes in the source network.
That should produce an even better MOSFET emulation of a half-12AX7 triode than KMGs original design.
There is an even simpler way: simply add a second LND150 as a source-follower, direct-coupled to the drain of each KMG MOSFET stage. Add a 39k resistor in series. Bob's your uncle, you now have a 40k output resistance!
Of course this doubles the number of LND150s you need, but the little MOSFETs are cheap. Eighty cents apiece at Digikey, in Canadian money.
-Gnobuddy
Thanks for that insight, may be very usefull for future experiments. So far I have been mostly interested in trying to use the KMG trickery on low voltage stages, with j113 jfets. But never focussed much on the output impedance and how that affects the sound, interesting new angle.
I still have a dream that it is possible make a simple solid state guitar amp that behaves and sounds 'rock&roll'. But it has to be Lo-Fi, as you say, basically a bad amplifier. It should be like a vox or fender 5e3, biased well into class A region, no or very little feedback. And use jfets where you can.