If the speaker only has 1mm of VC overhang or less it’s quite possible. And not unusual for a guitar speaker. The idea is to maximize midband sensitivity at the expense of LF capability. You normally don’t feed it full amp output at 82 Hz - there is usually quite a bit of bass cut employed. Model them in any given speaker box program. Some are designed/voiced for low end grunt. They will fall at the LOWER end of the sensitivity range - say, 94 dB/2.83V/1m.
Correct .8 to 1mm Xmax is about normal for guitar speakers
it is underhung within the gap of course.
The gap might be 5 to 8mm and suspension is pretty tight
so mechanical damage is not as easy as a overhung speaker.
But they have to be designed that way so guitar players can blast them open back / open baffle
without smacking the rear magnet
But why talk thermal ratings with guitar players
rather paper aluminum or kapton coil formers yada yada
30 75 or 150 watts rating
They hit distortion rather quickly about 15 watts regardless and max SPL for a single 12" is about 119 dB regardless. Since all of them wont be much more than .8 to 1mm and few rare special design that go to 2mm
Why would we simulate or even talk to people that design speakers LOL
should make wild guesses, and use add copy wattage ratings for live sound engineering.
Last edited:
There's a lot of great technical info here so far...
For the more esoteric though...
And, I'm just stating another opinion here—earlier there was a comment about all tube guitar amps being 50 variations of one amp—while this is probably true (wow Leo Fender?), my ears do tell me a different story in the search for what I like, and it seems a little simplistic to me to rule out the details like that in a broad stroke... but this thread reminds me of the conversation I have with myself all the time regarding tube guitar amps and vinyl playback.
On paper neither of these sonic efforts make any sense, solid state and digital, win no contest, on the page as far as my research tells me and I'm no self described expert in anything. BUT. I can tell you that i have yet to find a playback method that bests, to my ears, vinyl playback (and I'm not alone—and would happily give up records if I heard something better)... and I have yet to hear a solid state guitar amp that moves me as a guitar player, this IS more complex a condition that just what I hear, as "feel" is a thing. I'm surely biased, but really i don't think I am. LOL.
Is it possible there's something organic in these "analog" methods that vitalizes the human at a level that isn't quantifiable? (but is fun as hell to argue about?)
Here's a dirt cheap tube amp that people seem to love.
and here's a dirt cheap solid state amp that people seem to love.
The specs are likely pretty comparable in reality despite the advertised wattage difference. A lot might depend on what exactly you want to play....And when it comes to "solid state" guitar amps—is "modeling" a thing vs. the "sound" of whatever chip is chosen to base a DIY SS design on? The SS amp above is playing back a programmed version of X amp—that was probably a tube amp.
I wonder.
Let us know what you decide to build! Or buy....
(PS—I'm NOT a "tube" guy. The hi-fi music setup is fully solid state, I've played with tubes there, but all the components are relative—and ALL the details paint a picture and seem to matter...)
For the more esoteric though...
And, I'm just stating another opinion here—earlier there was a comment about all tube guitar amps being 50 variations of one amp—while this is probably true (wow Leo Fender?), my ears do tell me a different story in the search for what I like, and it seems a little simplistic to me to rule out the details like that in a broad stroke... but this thread reminds me of the conversation I have with myself all the time regarding tube guitar amps and vinyl playback.
On paper neither of these sonic efforts make any sense, solid state and digital, win no contest, on the page as far as my research tells me and I'm no self described expert in anything. BUT. I can tell you that i have yet to find a playback method that bests, to my ears, vinyl playback (and I'm not alone—and would happily give up records if I heard something better)... and I have yet to hear a solid state guitar amp that moves me as a guitar player, this IS more complex a condition that just what I hear, as "feel" is a thing. I'm surely biased, but really i don't think I am. LOL.
Is it possible there's something organic in these "analog" methods that vitalizes the human at a level that isn't quantifiable? (but is fun as hell to argue about?)
Here's a dirt cheap tube amp that people seem to love.
and here's a dirt cheap solid state amp that people seem to love.
The specs are likely pretty comparable in reality despite the advertised wattage difference. A lot might depend on what exactly you want to play....And when it comes to "solid state" guitar amps—is "modeling" a thing vs. the "sound" of whatever chip is chosen to base a DIY SS design on? The SS amp above is playing back a programmed version of X amp—that was probably a tube amp.
I wonder.
Let us know what you decide to build! Or buy....
(PS—I'm NOT a "tube" guy. The hi-fi music setup is fully solid state, I've played with tubes there, but all the components are relative—and ALL the details paint a picture and seem to matter...)
Last edited:
Nothing to spin you head, already told him 25 to 30 volt rails is all you need for a single 1x12
and the VA wont be much more than 80 to 160 depending if your a manufacture and want to rate it
at " 4 ohms" for max nonsense wattage rating possible.
If 1x12 aint loud enough use a 2x12 manufactures figured that out a long long long time ago.
pretty simple to make a amp for a 1x12
Since we are " making" a amp its good to know what voltage and current
you expect from a transformer that will power it.
And since it was clearly described what max SPL and voltage to expect from guitar speakers.
It will be a huge mystery why so so many 1x12 combos dont go over a certain power rating
He's been trying to get help to build an SS amps to faithfully amplifiy his already cooked and seasoned Guitar sound for 5 pages and he got 4.5 pages of naysayers telling him to build something else he does not want to.
NO suggestion was even to build a 100W+ Tube amp which potentially could do that but to build all kinds of 210-15-20W tube amps, many using WONKY tubes and UNTESTED designs "so they clip nice"
WHERE does he ask for that?
Not in this thread for sure.
It must be very frustrating by now.
To boot, SS amos are unfairly bring accused of all kinds of 60's problems: rail sticking, dropping squarewave clipping, self destruction with full power high frequencies, the works.
Guys, it's 2024!
Not forgetting that those problems were already tackled in the 70s!
Driver transformers? ..... SERIOUS? ..... why not suggest Germanium too? 😉
@JMFahey thank you for saying that.
Now that I’ve heard a lot of back and forth on this thread, I think that if I stick to my idea of building a solid state power amp is to either go with a bridge TDA7293/4 or clone the power amp of an existing discrete solid state guitar amp such as Peavey, Epiphone (Triggerman 100), Yamaha G100, etc.
The thing is, I know what I would like the power amp to be able to do, but I don’t know how to manipulate or build one to do it.
I’m willing to learn so maybe the first step is to try to duplicate something already known to work?
This might be a silly question but would it be a bad idea to build it on Tagboard? I have quite a bit of it.
Now that I’ve heard a lot of back and forth on this thread, I think that if I stick to my idea of building a solid state power amp is to either go with a bridge TDA7293/4 or clone the power amp of an existing discrete solid state guitar amp such as Peavey, Epiphone (Triggerman 100), Yamaha G100, etc.
The thing is, I know what I would like the power amp to be able to do, but I don’t know how to manipulate or build one to do it.
I’m willing to learn so maybe the first step is to try to duplicate something already known to work?
This might be a silly question but would it be a bad idea to build it on Tagboard? I have quite a bit of it.
Those problems still exist in 2024 - thanks to the BEAN COUNTERS making PA amps cheap. You can make it totally free of those artifiacts, and it starts with a big enough transformer and two 10,000 uF caps. Or 20,000 for stereo. And no, a smaller amplifier does not use smaller caps - it’s based on the TIME CONSTANT between the cap and the load impedance. And when you scale the impedances UP to tube levels, it turns out the typical 100 uF cap is plenty. Its one reason they clip as nicely as they do.
We can of course go all tube, make it clean as a whistle with all the headroom you’ll ever need (200 watts). Uses no exotic or hard to source parts, and is now full tested. Design details have been posted in my “6550“ thread. Each one now comes with a $1500 price tag post Covid. Even half the power is serious money. A solid state “equivalent“ can be built for about half, and doesn’t weigh much less. That BGW clone is fully tested too - I’ve been running it for 20+ years. And it has gigged with 2 ohm loads at war volumes for hours.
I was trying to suggest alternatives that are loud enough, a little more sane and a lot less costly.
We can of course go all tube, make it clean as a whistle with all the headroom you’ll ever need (200 watts). Uses no exotic or hard to source parts, and is now full tested. Design details have been posted in my “6550“ thread. Each one now comes with a $1500 price tag post Covid. Even half the power is serious money. A solid state “equivalent“ can be built for about half, and doesn’t weigh much less. That BGW clone is fully tested too - I’ve been running it for 20+ years. And it has gigged with 2 ohm loads at war volumes for hours.
I was trying to suggest alternatives that are loud enough, a little more sane and a lot less costly.
Attachments
Yes duplicate something that is known to work.
And or understand basic amplifier topologies
and the can of worms that come with it.
Basically yes you just need to know how a amps work.
And other things that you can add because your not marketing a amp.
You can beef it up, add more transistors for heat dissipation
and use larger more healthy transformer than most manufactures.
You can also use better semiconductors than the usual general purpose
amplifiers
You can reduce the usual somewhat noisy power supplies used
and also beef them up. Not much different than " Hi FI "
amps.
You can breadboard a amp yes.
But for reliable operation and high power it leads to a PC
board, and learning how to lay out a pc board.
Something also “known to work”. I had two of these homebrew units an used them gigging for my entire college career and a little beyond. Supposed to be like a Crown DC300A, but with all the improvements that were made for the PV CS800 and full comp outputs which are less prone to oscillation. I got 80v/8A EI transformers for next to nothing (toroid $85 today from Antek). So that determined the size of what got built. With 8 output transistors per channel they are good for bridging into 4 ohm, with a DJ at the helm. I was that DJ and I do not have irrational fear of clipping. Two pair is enough for most normal use. One works just fine on +/-42 volt rails (Can reduce the SOA circuit resistors to 3.3k). I’ve used this same thing scaled to all kinds of power levels over the years, and made them with class G and H multi rail supplies. Hi fi, instrument, PA. The SS one above uses a symmetrical VAS (like the BGW), +/-84V, and 7 pairs of outputs. I’ve gone bigger, too. The original KM441 transistor set is NLA, but works if the substitute is designed for the same purpose. 15003/4 outputs, C5200/A1943 drivers, and your favorite fast TO-126 for the vas and predriver for these rail voltages. For a single channel use a 400VA trafo for +/-55-60, and 300 VA for +/-40-42.
Attachments
To have a fully working amp within a Month and minimal "new variables" or "unknowns" , out of your latest options I would pick the bridged TDA7294 option.
Why?
Because apparently the PCBs are available.
Not a full kit (which would be great for a first build) but the most complex part of it.
Components are standard and cheap, a PT will be easy to source.
If anything Antek probably has a suitable one, no need for filament windings, etc.
If not exact match found, pick one 2 or 3 Volts lower, which is safer.
Heatsinking?
Follow what original project suggests and if it says nothing, copy what other bridged or stereo 7294 projects use.
One BIG problem for DIYers is sourcing all parts, so let's keep that simple.
You'll need a suitable chassis.
Commercial ones are available, DIYAudio offers some nice ones too, and some matching heatsinks too.
If not, just as an example, my very first amps were built on local shop made ones.
Since I come from a rural town in the middle of the Pampas, all I found was the local tinsmith, a guy making food and water holders for hens , pigs and cattle, drain gutters, etc.
He had the necessary shears and folders 😄
Somebody above suggested a HVAC shop ... same thing.
Or maybe somebody doing bodywork for trucks.
He made me a U shaped chassis out of 1.5mm (1/16") aluminum.
Not rigid on its own but I screwed in right and left sides made of hardwood.
The resultant box was rigid.
Early Marshall chassis were built that way 😲
Notice the upside down U shaped aluminum chassis, bolted on both ends to a cast aluminum block for rigidity.
I suggest aluminum over iron because it does not need special finishing, does not rust, is easier to drill, punch, file, etc. because it's softer, etc.
The option would be to clone a commercial amplifier, such as the Yamaha 100.
Excellent amps, but you would have to design a PCB from scratch 🤷🏻
Which in general requires debugging/troubleshooting/tweaking.
Fine for a commercial product which will sell hundreds or thousands, not so much for "just one"
Why?
Because apparently the PCBs are available.
Not a full kit (which would be great for a first build) but the most complex part of it.
Components are standard and cheap, a PT will be easy to source.
If anything Antek probably has a suitable one, no need for filament windings, etc.
If not exact match found, pick one 2 or 3 Volts lower, which is safer.
Heatsinking?
Follow what original project suggests and if it says nothing, copy what other bridged or stereo 7294 projects use.
One BIG problem for DIYers is sourcing all parts, so let's keep that simple.
You'll need a suitable chassis.
Commercial ones are available, DIYAudio offers some nice ones too, and some matching heatsinks too.
If not, just as an example, my very first amps were built on local shop made ones.
Since I come from a rural town in the middle of the Pampas, all I found was the local tinsmith, a guy making food and water holders for hens , pigs and cattle, drain gutters, etc.
He had the necessary shears and folders 😄
Somebody above suggested a HVAC shop ... same thing.
Or maybe somebody doing bodywork for trucks.
He made me a U shaped chassis out of 1.5mm (1/16") aluminum.
Not rigid on its own but I screwed in right and left sides made of hardwood.
The resultant box was rigid.
Early Marshall chassis were built that way 😲
Notice the upside down U shaped aluminum chassis, bolted on both ends to a cast aluminum block for rigidity.
I suggest aluminum over iron because it does not need special finishing, does not rust, is easier to drill, punch, file, etc. because it's softer, etc.
The option would be to clone a commercial amplifier, such as the Yamaha 100.
Excellent amps, but you would have to design a PCB from scratch 🤷🏻
Which in general requires debugging/troubleshooting/tweaking.
Fine for a commercial product which will sell hundreds or thousands, not so much for "just one"
@JMFahey
I think you’re right. The TDA7294 would probably be the best way to get my feet wet.
I may look around for an Orange Crush schematic. I think the 60 watt and 120 watt use the 7294 chip.
I’m interested if they do anything different than a HiFi power amp.
When it comes to power, should I go for extra? Is toroidal better?
Stay away from smps?
From what I’ve read, tube guitar amps use less filtering, under-rated transformers (exceptions exist, like HiWatt), and have low damping and high output impedance. There are also a lot of amps that get a lot of distortion from pushing the phase inverter into clipping.
I can see adding a preamp stage right before the power amp that is meant to be overdriven.
But should the rest of it be simulated or can this be done with a solid state amp?
I know that Quilter amps have a limiting circuit to keep the power amp protected. They also have a way to lower damping
I think you’re right. The TDA7294 would probably be the best way to get my feet wet.
I may look around for an Orange Crush schematic. I think the 60 watt and 120 watt use the 7294 chip.
I’m interested if they do anything different than a HiFi power amp.
When it comes to power, should I go for extra? Is toroidal better?
Stay away from smps?
From what I’ve read, tube guitar amps use less filtering, under-rated transformers (exceptions exist, like HiWatt), and have low damping and high output impedance. There are also a lot of amps that get a lot of distortion from pushing the phase inverter into clipping.
I can see adding a preamp stage right before the power amp that is meant to be overdriven.
But should the rest of it be simulated or can this be done with a solid state amp?
I know that Quilter amps have a limiting circuit to keep the power amp protected. They also have a way to lower damping
I don’t usually look to The Gear Page for actual useful information but the first post here was helpful
The Amp Myths
“Now, there is a way to reduce damping factor and make a solid-state power stage behave much like a tube output stage. That is done by changing the topology such that the speaker forms part of the resistive divider that is the feedback loop. The resistance used to ground, Rg, of the resistive divider used for the feedback loop is less than the nominal impedance of the speaker, which functions as Rf. The feedback loop determines the gain of the output stage. The formula for gain equals Rf divided by Rg plus 1. If Rf goes up, the gain of the circuit goes up; hence, it causes power to increase with increases in load impedance much like a tube amp. Marshall first used this topology with their ValveState amps. The tube in the preamp is about as much for show as it is for sound.”
The Amp Myths
“Now, there is a way to reduce damping factor and make a solid-state power stage behave much like a tube output stage. That is done by changing the topology such that the speaker forms part of the resistive divider that is the feedback loop. The resistance used to ground, Rg, of the resistive divider used for the feedback loop is less than the nominal impedance of the speaker, which functions as Rf. The feedback loop determines the gain of the output stage. The formula for gain equals Rf divided by Rg plus 1. If Rf goes up, the gain of the circuit goes up; hence, it causes power to increase with increases in load impedance much like a tube amp. Marshall first used this topology with their ValveState amps. The tube in the preamp is about as much for show as it is for sound.”
If you have your heart set on this amp, ebay cant be beat; https://www.ebay.com/itm/325729464495
If you like to solder, you can save a couple $ and get the full kit. It's less than $20 assembled! At least it shows the schematic, which you could present here for questions. Like how to invert one of the channels to get your push-pull, or implement the feedback differently.
You'll still need a power supply and thermal solution. Ebay and like places cant be beat for SMPS power, which is fine to start with, IMHO, particularly for guitar. We used to make them droop output voltage with current - like a transformer and diodes - so there is a way to do that too. It's just the opposite of what everyone wants - that "tight regulation" - so it's unlikely to get that off the shelf.
I think the chassis ebay offers are expensive. $28 to ship an aluminum chassis; c'mon - I can add...
I'd start simple , the goal being to have a working and competent amp within, say, 1 Month.
Properly mounted inside a chassis and case, inside a cabinet, even if only 4 MDF pieces glued and nailed together, which you can actually move around (breadboards can not or should not 😄), so you can actually take it to your rehearsal room and use it live, driving your 12" speaker and playing with your friends.
That beats experimenting alone in a musty spiderweb covered dungeon or asking in a Forum 100:1 😄
Then you tell us how it behaves, live, besides your friend's commercial amp but above all against that unbearable noise source: the drummer!!! 😉
Properly mounted inside a chassis and case, inside a cabinet, even if only 4 MDF pieces glued and nailed together, which you can actually move around (breadboards can not or should not 😄), so you can actually take it to your rehearsal room and use it live, driving your 12" speaker and playing with your friends.
That beats experimenting alone in a musty spiderweb covered dungeon or asking in a Forum 100:1 😄
Then you tell us how it behaves, live, besides your friend's commercial amp but above all against that unbearable noise source: the drummer!!! 😉
I was trying to simulate a person that designed speakers, no luck, so I guess I have to ask. Could you show measurements of guitar speakers distorting at 15W?
You still are talking about volts when inquiring minds want to know how guitar amps manage to put out low frequencies for the drop-D crowd.