Rod Elliot’s designs are cool. I’ve looked at his TDA7294 design but the warning about the power supply scared me.
I’ve also looked at one of his Mosfet designs and I think BJT one too.
I know that I could use an 8ohm speaker but I like that speaker and would like to keep the cabinet stock.
The Bandit doesn’t sound quieter through it.
Maybe I should veer away from hifi designs and look at “pro” or “live” designs (QSC, Crown, etc).
Side note: I’ve read about Frequency Dependent Dampening and Current Feedback both being ways to lower damping and increase output impedance so that the speaker behaves similarly to a tube power amp’s output transformer behaves.
Is there any truth to that? If so, does it make a significant difference?
Since this is for guitar, that reaction seems to be really important.
I have limited experience with solid state amps, but I have always been confused by people saying they sound so much worse than a tube amp.
The speaker (and the cabinet) seem to make a big difference in person.
You certainly rub shoulders with the Gods 😄😄😄
As of chipamps in Guitar amp use, they are incredibly good and practical , a GREAT invention, killer specs, inexpensive, but their very small size is a (thermal) limitation.
Namely: too much heat in a very small package with very small heat spreading surface.
Nothing more nothing less.
No problem at all if putting out, say, 40W RMS, maybe 50W for TDA729* ... and no more.
I mean in an abusive job such as MI duty.
Why? ... both are packed in a slightly enlarged TO220 case, in fact some call it "5 pin TO220"
Size and contact surface is exact same as 2 TO220 cases side by side ... way too close for comfort.
Heat put out by one gets squarely into te other half and viceversa, each can use only it's half of the heat sink, etc.
FWIW when LM3886 disappeared everywhere 3 years ago, I had to design a mini board to replace it in Servicing.
I made a discrete one 😲 based on a TIP121/126 TO220 Darlington pair.
Separated edges by about 1", mounting centers by about 1.5", so "one does not fight the other", go figure.
Worked like a charm, and even so tried not to pull more than 50W RMS out of them; any larger and I used TIP142/147 instead.
I had originally designed such a board to replace once very popular TDA1514 (Marshall Valvestate 40 , Chorus 80 and VS 40+40 rack amp of Billy Gibbons fame) which had absolutely disappeared from the market.
Someone drawn to ice power modules or chip amplifiers in general may not have the experience necessary to tackle a large discrete amplifier. Small one yes, big one no. Maybe a “first” amplifier ought to simply be in the 20 watt range. Chips can be used without requiring a heat sink the size of Texas, and far less chance of smoke and flame.
A pair of 2N3055 run at max VCER will run 40C cooler at the die level than an LM3886 on the same heat sink at the same 70V supply at war volume. Thats what’s wrong with using chip amps pushed that hard. Running it as a 20W amp at reduced supply brings the junction temperature back to the realm of sanity.
20 watts is still pretty loud. That’s all you’ll get from a pair of EL84’s. Build bigger as you gain experience.
Tubes (or more correctly the circuits that use them) do produce colorations that are hard to emulate with solid state. Not impossible, but it is its own engineering challenge, over and above making a reliable power amp. Most of the nasty “Solid state sound” can be traced to gain structure problems in the preamp. That can be designed around and produce a workable compromise.
A pair of 2N3055 run at max VCER will run 40C cooler at the die level than an LM3886 on the same heat sink at the same 70V supply at war volume. Thats what’s wrong with using chip amps pushed that hard. Running it as a 20W amp at reduced supply brings the junction temperature back to the realm of sanity.
20 watts is still pretty loud. That’s all you’ll get from a pair of EL84’s. Build bigger as you gain experience.
Tubes (or more correctly the circuits that use them) do produce colorations that are hard to emulate with solid state. Not impossible, but it is its own engineering challenge, over and above making a reliable power amp. Most of the nasty “Solid state sound” can be traced to gain structure problems in the preamp. That can be designed around and produce a workable compromise.
I don’t have any experience. I’ve stated that multiple times. I have never built an amp.
That is why I was looking at kits. I would just as happily build a kit from discreet components. Those were just kits I found when searching.
In my experience, a 15-20 watt el84 tube amp will be incomparably louder than a solid state amp rated at 20 watts. There are also other things going on that I don’t know the physics of but that’s why I made an account. I want to learn.
I don’t mind being told that I should start smaller, but I haven’t found any threads asking these questions specifically about using what I am assuming are hifi power amps for guitar. Maybe I need to get more schematics and study them.
If I could build a kit based on old rack power amps, I would. I haven’t seen a lot of info on that.
Obviously they won’t be free, but the total cost for the solid state amp would definitely be cheaper. A matched pair (or quad) of good quality power tubes is going to be more expensive than transistors.
The power transformer will be cheaper than the 2 for the tube amp.
Why would I want to design it? I’m asking about kits or at the very least examples of circuits that would work and be possible to build.
@turk 182 Watts are the same, but watts isn't always equivalent to output. I guess it can be if you're in the HiFi world where everything is suppose to have the lowest distortion possible, but with guitar amps driving the power amp section into clipping is desirable, even if just slightly. The harmonics and clipping are often smoothed out by the output transformer, so they can sometimes be perceived as not clipping (to your ears, not when measuring them).
This is why you see 20-50 watt tube guitar amps being used in bands, but anything below 50 watts solid state with a reasonably loud drummer will be inaudible. I use to think it was the speakers until I was able to run multiple amps through the same speaker cabinet. It might even have less to do with output level (db) and more to do with harmonics and "push" for lack of a better term or understanding.
This is why you see 20-50 watt tube guitar amps being used in bands, but anything below 50 watts solid state with a reasonably loud drummer will be inaudible. I use to think it was the speakers until I was able to run multiple amps through the same speaker cabinet. It might even have less to do with output level (db) and more to do with harmonics and "push" for lack of a better term or understanding.
The myth is real. More correctly, SS watts often sound worse/less loud if they are not implemented well. Design the amp and power supply for that 20 or 60 watt sand amp on the same way you would for an Iron Pig Break Your Back touring grade PA amplifier from the 1980’s and it will be just as “loud” as a 20 or 60 watt tube amp. Nobody does, for a wide variety of sometimes perfectly valid reasons. What you end up with physically DOES produce less power under real world conditions, even if you can play specsmanship games and arrive at the same rating.
Most tube amplifiers can be overdriven about 6 dB before you even NOTICE that anything is distorting at all. SS amps can do the same - but to do so makes them expensive and heavy, and usually compromises the THD20k that could otherwise be achieved. But most don’t, either because of economy or the pursuit of one PPM distortion, so there is an apparent 6 dB increase in apparent “tube watts loudness”.
Most tube amplifiers can be overdriven about 6 dB before you even NOTICE that anything is distorting at all. SS amps can do the same - but to do so makes them expensive and heavy, and usually compromises the THD20k that could otherwise be achieved. But most don’t, either because of economy or the pursuit of one PPM distortion, so there is an apparent 6 dB increase in apparent “tube watts loudness”.
ok now that we're talking about pushing the "output stage" into distortion/saturation i'll concede that a tube amp can be perceived as louder than a solid state.
and i don't care that your an audiophile or musician or just a lay person most would agree that whats coming out of a tube stage at war volume sounds better than what's coming out of the SS.
you can't push a SS output into distortion like a tube stage output, SS guitar amps designs that i've looked at all seem to rely on preamp level created distortion, diode clippers and such, whereas with tubes low watt outputs driven into saturation/clipping is a sound that is sought after.
not to seem like a tube advocate i worked with a guitar player who got his hands on an old Cerwin Vega amp, one meant for Sensurround sub use in a theater, he claimed that as a bandwidth limited amp he did not get the, as he called it "the exaggerated high end" of other SS amps.
he did have a great tone!!
and i don't care that your an audiophile or musician or just a lay person most would agree that whats coming out of a tube stage at war volume sounds better than what's coming out of the SS.
you can't push a SS output into distortion like a tube stage output, SS guitar amps designs that i've looked at all seem to rely on preamp level created distortion, diode clippers and such, whereas with tubes low watt outputs driven into saturation/clipping is a sound that is sought after.
not to seem like a tube advocate i worked with a guitar player who got his hands on an old Cerwin Vega amp, one meant for Sensurround sub use in a theater, he claimed that as a bandwidth limited amp he did not get the, as he called it "the exaggerated high end" of other SS amps.
he did have a great tone!!
The trends use to be that most solid state guitar amps rated under 100 watts are practice or beginner amps and the ones that were around 100 watts or more were for the young musician that can't afford a tube amp or possibly the working musician that wanted something reliable and loud with virtually no maintenance . As @wg_ski said, the power supplies aren't well-designed for lower watt solid state guitar amps because they aren't made to be played loud or pushed hard.
I've looked at schematics of older solid state guitar amps and most of them (except Orange) did seem to use discrete parts over chipamps. That is to say that while I can identify what components are and I could draw them out, I don't understand topology terms or how/why certain configurations were implemented or how those configurations effect things like eq of the power amp or response (FDD, current feedback, etc).
I'm thinking that I need to try to do some research on older discrete power amp designs and find some books to read up on before I'm going to be able to build something.
I have a Helix and I could buy a powered PA speaker that would make the paint chip off the walls, but I thought it would be more fun to try to build my own power amp and use a traditional speaker.
I greatly appreciate any education or advice anyone wants to provide! And thank you for the responses thus far.
I've looked at schematics of older solid state guitar amps and most of them (except Orange) did seem to use discrete parts over chipamps. That is to say that while I can identify what components are and I could draw them out, I don't understand topology terms or how/why certain configurations were implemented or how those configurations effect things like eq of the power amp or response (FDD, current feedback, etc).
I'm thinking that I need to try to do some research on older discrete power amp designs and find some books to read up on before I'm going to be able to build something.
I have a Helix and I could buy a powered PA speaker that would make the paint chip off the walls, but I thought it would be more fun to try to build my own power amp and use a traditional speaker.
I greatly appreciate any education or advice anyone wants to provide! And thank you for the responses thus far.
anyone but me remember these... with the built in distortion!!
i'd copy the output stage of a G 100, common TO3 transistors outputs as i recall should be dead simple.
there are no vintage Orange solid state designs back in the day they only made tube amps it's only since the brand has been brought back from the ether that SS comes out to play.
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I will see if I can find the schematic for the G100. I've never played one, but it was actually the interview video with Paul Rivera that put the term "current feedback amplifier" in my head.
You are correct about Orange. I will say that their solid state stuff is really good. They keep everything relatively simple in terms of controls and features and their power amp sections are loud
You are correct about Orange. I will say that their solid state stuff is really good. They keep everything relatively simple in terms of controls and features and their power amp sections are loud
It's only since someone realized they could leverage that brand with Chinese manufacturing to make money marketing a look-alike to their vintage stuff.
That said, maybe they do something innovative like a current source design, allowing the speaker something softer to reactively push against. I dunno.
It could be thermals as to why this discretization of an otherwise available integrated design makes for a more reliable product. Think about it, you have one package dissipating heat over here, a second one over there - versus both crammed onto a single small, sad surface area to pass the heat through.
One of the last conversations I had with a thermal engineer at work she said the power keeps going up, the surface area keeps going down - and they expect us to design a solution for it, no matter what.
It would be wild for an amplifier company to use the same brand and aesthetic that made them famous and have things built cheaper for them outside the US. Never seen any brand do that before, especially not a guitar amp company
In all seriousness, I have heard that vintage Orange amps were built like bulletproof works of art. Loud, clean, and well-designed. But their modern amps are not bad by any means. They wouldn't be a house-hold name if they didn't make great amplifiers and were used by tons of musicians.
Lets also not forget that part of that relaunch started the lunchbox tube amp trend. And rightly so, the Tiny Terror is probably the most rock and roll modern amp design around.
Again, the Crush amps are also held at a higher tier than most. They are one of the few companies that hasn't moved to digital signal processing for their affordable amp designs. At least they are still trying to build (and improve on themselves) analog amplifiers.
You see TR307 and TR308 there in the power amp of the first pdf? Those monitor the current going through the output devices and will clamp their drive in the event of an over current condition - on a fast cycle by cycle basis. See the table of values for R!, depending on the 50 or 100W model?
Because this design has that circuit, I'd say its power amp will survive more "punishment" than a different deign without such feature. It's something to look for when considering the efficacy of different SS amp designs for use with guitar. Not that all guitarists are abusers of their gear, but I'm sure Yamaha has learned that enough of them are, to include that "extra feature" to protect their brand reputation.
Not that a customer doesnt mind their amp not blowing up when they connect a shorted speaker cable to output #2, unawares.