Yes, that's the new trend.
They try to fully remove power amp and speaker out of the equation by grossly overrating both and making speaker HiFi/ recording studio monitor flat.
Not my cup of tea, but hey ... a way to go for some.
Personally I prefer a halfway point: a large loud (but not "monster") SS power amp, but driving an efficient Guitar speaker.
Again, to each his own.
They try to fully remove power amp and speaker out of the equation by grossly overrating both and making speaker HiFi/ recording studio monitor flat.
Not my cup of tea, but hey ... a way to go for some.
Personally I prefer a halfway point: a large loud (but not "monster") SS power amp, but driving an efficient Guitar speaker.
Again, to each his own.
A large, loud (but not monster) SS power amp still needs to be well-behaved to work well as an instrument amp. The overload characteristics of a poor one are still particularly nasty and aren’t going to help anyone’s tone.
Just because an amp clips VERY hard and very flat on top does not mean it sounds bad as a guitar amp. Quite the contrary - it is exactly what you want when you run out of headroom. TOO MUCH clipping simply means the amp is undersized. My BEST tube amp clips hard and flat, and doesn’t even sound like it’s clipping, even when the scope tells me that it is. The more that a solid state amp approaches that behavior, the better it tends to sound. Regardless of the application. That same behavior happening in the preamp ahead of ANY treble boost (or bass cut) sounds like hell. Poorly thought out op-amp based preamps have a nasty habit of doing just that - giving rise to the hated “transistor sound”.
Poorly built (or cheaply built) transistor power amps tend to have horribly tilted waveforms, conducted power supply ripple, stick to the rails, and possibly have gross crossover distortion that shows up at HIGH levels. All that stuff sounds awful. Doesnt matter if you’re playing a guitar at war volume or music. It just sucks.
OTOH, if that “clean clipping” is the only source of distortion it’s not going to sound right either. Guitar amplification needs the proper coloration in the preamp stages -which is why a hi-fi amp just doesn’t work plugging a guitar straight into it.
Just because an amp clips VERY hard and very flat on top does not mean it sounds bad as a guitar amp. Quite the contrary - it is exactly what you want when you run out of headroom. TOO MUCH clipping simply means the amp is undersized. My BEST tube amp clips hard and flat, and doesn’t even sound like it’s clipping, even when the scope tells me that it is. The more that a solid state amp approaches that behavior, the better it tends to sound. Regardless of the application. That same behavior happening in the preamp ahead of ANY treble boost (or bass cut) sounds like hell. Poorly thought out op-amp based preamps have a nasty habit of doing just that - giving rise to the hated “transistor sound”.
Poorly built (or cheaply built) transistor power amps tend to have horribly tilted waveforms, conducted power supply ripple, stick to the rails, and possibly have gross crossover distortion that shows up at HIGH levels. All that stuff sounds awful. Doesnt matter if you’re playing a guitar at war volume or music. It just sucks.
OTOH, if that “clean clipping” is the only source of distortion it’s not going to sound right either. Guitar amplification needs the proper coloration in the preamp stages -which is why a hi-fi amp just doesn’t work plugging a guitar straight into it.
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You missed one. There is a 45 volt 100 mA version of the 6CW5 called the 45B5/UL84. These tubes contain the same guts as the EL84 except the screen grid. It is closer to the cathode so the UL84 needs to be treated like a TV sweep tube with about 175 volts on G2. Up to 25 watts can be extracted from a pair into a 3300 ohm load on about 300 volts.
The HBAC taught us how to make a low buck amp. I made the little 4 tube 4 watt amp for under $50, but it had a big brother that made 15 to 20 watts for under $100. It is the amp head that is seen on top of the cabinet in post #58. I put one of my 6600 ohm OPT's into it wired for 3300 ohms and now get a bit over 20 watts at 3% THD and the meter reads 27 watts with all the knobs dimed and the low E string plucked....not really a valid test though.
I am including the schematic. All of the mosfet stuff in the preamp cathodes can be ignored. They are part of a variable gain idea that did not work and was bypassed. I will stuff some J-fets into the PCB and try again when I have the amp open. The similarities to a "Marshall 18 watt" schematic were intentional. My "too many diodes" power supply shows how to make a tube amp with a $20 power transformer. An 80VA isolation transformer is used to power all the series wired tube heaters, provide 340 volts of B+ and 170 volts for the output tube screen grids. I added an extra preamp tube since 12AX7's with a 20 volt 100 mA heater (the 20EZ7) are rare and expensive, so I used 26AQ8's which were cheap but have lower gain. The amp had way too MUCH gain so one stage was bypassed in the current amp.
I agree with you, op amp clipping is not a pleasant distortion to my ears either. A lot of SS guitar amps can suffer from that, if the designer is not careful. Guitarists/bassists like to push the inputs of amps, and overdriving an op amp input is not going to give the "expected results" the musician wants.
A +/-15 volt power supply is a severe limitation in a guitar front end! Pickups can produce a lot of peak voltage, and the headroom offered by a simple 12AX7 cannot be ignored. Biased at low current, they will also produce compression as the output voltage tries to skyrocket rather than just clip off at +/-13V. You can “fix” this limitation - it’s just not simple and intuitively obvious. What you end up needing are lower noise op amps so that the front end gain isnt so high that it clips right away. Do all the processing 20 dB below levels that you’re used to working. Then amplify the signal.
Sure it would be more interesting to do a SS amp, but it could take some time and money to get there. I doubt the OP will feel too happy with a blown output section due to high frequency oscillations. If he had more experience or we all would be tinkering the circuit along with him then I might say yes. I have my own ideas on building a SS amp, just do not have the time to devote to it right now.
Actually I thought of using a laptop supply for the heaters. About $4 in a thrift store. Did not realize they were that inexpensive. Mind you, I was hoping to get the transformers from the same place to not have to pay multiple shipping charges.
https://www.antekinc.com/as-1t300-100va-300v-transformer/
Since transistor can directly drive a load.
What is the point.
Driver stage with transformer was a interest.
There is not really a benefit and it complicates the design.
Good luck getting stable bias and making it thermally stable.
Why make wild guesses, you would have to be able to
at least model the amplifier in spice simulation.
To get voltage swing and matching needed
the model would help you figure out the needed ratio.
for needed frequency response and wire gauge needed for
current involved, good luck.
What is the point.
Driver stage with transformer was a interest.
There is not really a benefit and it complicates the design.
Good luck getting stable bias and making it thermally stable.
Why make wild guesses, you would have to be able to
at least model the amplifier in spice simulation.
To get voltage swing and matching needed
the model would help you figure out the needed ratio.
for needed frequency response and wire gauge needed for
current involved, good luck.
Its easier to not re invent the wheel.
Your either building 6V6 , 6L6 or EL34
output pair.
And there is power transformers/ output transformers
already to go. Including the low voltage/high current
windings for the heaters. Already integrated into the power
transformer
Its a Celestion G12H Creamback 75 watt speaker.
Higher wattage would be mostly for headroom, but maybe I am thinking about it in the wrong way.
I found out the guy before me used a 75 watt 112 amp and had no problems keeping up. I worry that 30-40 watts would not be loud enough with a 1x12
More speakers usually means more weight. Partially defeating the purpose of ss over tube amp (not entirely)
This is actually similar to how the other guitar's amp is behaving.
It uses digital amp modeling that runs into an ICEPower 100 watt @ 4ohm load. Speaker is a 100 watt 4 ohm Celestion design that is suppose to be more flat so that the speaker modeling will be part of the tone shaping. The cabinet is open back so it is more like a traditional amp experience.
I could buy an FRFR speaker - a powered PA wedge or one of the ones that are more like a traditional guitar cabinet (Kemper Kab, Line 6 Power cab, Laney FR112, etc), but I think that a traditional amplifier might sound and work better for this type of band,
As I learn more, I am realizing that it might be more cost-effective to buy something off-shelf. The Boss Katana is a 100 watt (8 ohm) head that has a power-amp in so I can just use the power amp or I can use the digital preamp if I want. The power amp is Class AB but I have no idea what they are using.
I see them used for under $300 often. Also, if I combine my 16 ohm cabinet with a second 16 ohm cabinet, that will put me at 8 ohms. The amp also has power reduction (100, 50, and 1 watt settings)
I that doesn't stop me from wanting to build and try out different solutions.
Honestly, I didn't know that HiFi/music amplifiers were that much different than solid state guitar amp's power section until I started learning about the different circuits and techniques to make them behave more like a tube amp with an output transformer. My plan was going to be to use a variety of preamps and effects then another eq at the end right before the power amp (high and low cut) to try to get it to work better for my situation.
I feel like I've come pretty far since that thought
I have no idea. I am going to have to read through these pages and figure it out.
I almost feel more lost than when I started this thread
Yes correct 1x12 or 2x12
pretty normal for keeping up with most band situations.
75 watts is the thermal rating of the voice coil
before it melts.
Standard underhung voice coil with not much more than
1.5 to 2.5 mm of linear travel.
They hit breakup with about 10 to 15 watts
they turn to flubber with 25 to 30 watts.
Depends if sealed or open back.
Open back has no cone control, so the hit breakup
very quickly open back.
Its 100 dB so yes not much real power is needed
to reach band levels with guitar speakers.
Having heard couple zillion celestion loaded 1x12
guitar cabs over the years.
Better to understand as a engineer what voltages are
involved and how much transformer VA you actually need
to get to band levels with typical underhung speakers.
And know how much actual voltage the speakers can take
before they turn to flubber.
And how much voltage would literally destroy them.
Or simple look at what is involved with a zillion 1x12
solid state combo amps sold since the 70s.
Rectified rail voltage wont be around much more than 25 0 25
maybe 30 to 35 volt rails for bigger guitar amps.
And transformer wont be much more than 80 to 160 Volt Amps
which is more than enough to obliterate a 1x12
For " 100" watt amp transformer usually pretty weak to strong
180 to 250 volt amp.
Its a " 75" watt speaker so you need " 100" watt for overhead right?
NO... 75 watts is the thermal rating. Then turn to flubber with no more
than 30 watts. And depending how much you goose bass open back.
they will be physically damaged with far far less power.
pretty normal for keeping up with most band situations.
75 watts is the thermal rating of the voice coil
before it melts.
Standard underhung voice coil with not much more than
1.5 to 2.5 mm of linear travel.
They hit breakup with about 10 to 15 watts
they turn to flubber with 25 to 30 watts.
Depends if sealed or open back.
Open back has no cone control, so the hit breakup
very quickly open back.
Its 100 dB so yes not much real power is needed
to reach band levels with guitar speakers.
Having heard couple zillion celestion loaded 1x12
guitar cabs over the years.
Better to understand as a engineer what voltages are
involved and how much transformer VA you actually need
to get to band levels with typical underhung speakers.
And know how much actual voltage the speakers can take
before they turn to flubber.
And how much voltage would literally destroy them.
Or simple look at what is involved with a zillion 1x12
solid state combo amps sold since the 70s.
Rectified rail voltage wont be around much more than 25 0 25
maybe 30 to 35 volt rails for bigger guitar amps.
And transformer wont be much more than 80 to 160 Volt Amps
which is more than enough to obliterate a 1x12
For " 100" watt amp transformer usually pretty weak to strong
180 to 250 volt amp.
Its a " 75" watt speaker so you need " 100" watt for overhead right?
NO... 75 watts is the thermal rating. Then turn to flubber with no more
than 30 watts. And depending how much you goose bass open back.
they will be physically damaged with far far less power.
The FDA (fully differential amp) I'm building does this. The first stage is an LTP generating two out of phase signals, getting about 50VRMS undistorted for a 3V input. Those signals go through a dual "pre" control into a second tube arranged as the so-called "cold clipper". What emerges is two "halver-sines" going into another dual control, as input to the next stage, and the output tubes which can clip the tops off the halver-sines. Then the signal looks more like a modified square wave from an AC power inverter than a audio signal.
The details of the "next stage" are in flux; I just ordered the tube I want to try there last night. (I saw on line where Fred N made it work for audio amplification) The idea is based on my experience playing and singing through compressors and my seemingly natural affinity to "ride that wave". Kind of like Gilmour does with his stacked compressors. What wave is that? The amplitude envelope signal, controlling the VCA in the compressor.
I want my amp to play dynamically, that is the tone / harmonic content changes with the input signal. Obviously they do that anyway; let's just make that aspect even more apparent, if not more in your face. Why? Because you can. Wish me luck - I actually roughly heard what I want it to do, but I'm simply using the wrong tube at that point in the signal chain for what I'm trying to do.
Unless you happen to like the sound of a transformer enough to mitigate that complexity. And they do have a sound - all you have to do is run a signal through one and look at a spectrum analysis of what emerges. Couldnt be something common to Neve mixing consoles and Fender Princetons that so many have heard and like... I feel like I've said this somewhere before - Deja Vu.
Not a small signal transformer for a mixing console.
Those are off the shelf and easy to implement
Transformer for a solid state amplifier driver stage or amplifier output stage.
More than familiar with the topology
And more than familiar with the issue to implement bias and bias tracking.
There is real reasons to use transformers for small signal.
Making mystical magical guitar tone for power amplifiers
is easily done. Just use a transformer coupled tube amp.
There is probably at least 5 to 10 manufactures of transformers
and you could have a transformer by mail in 3 to 5 days.
And just make a good old tube amp.
Shoving transformers on solid state amplifiers is utterly pointless.
And dont even care to market a amp " That emulates a transformer tube amp"
Use 70 volt transformers for ceiling speakers. Frequency response is garbage.
But hey it would be just a high pass filter since they dont usually go below 80 Hz very well.
They are just 70 volt line distribution transformers for ceiling speakers
Be easier to use a tube preamp and shove a transformer in there somewhere.
Already been done for magical DI boxes that sell for about 2 grand.
I am a little confused by this. So, please bear with me.
Most amplifiers that I see and are solid pretty closely match the speaker wattage to the amplifier.
For example, my Peavey Bandit 112 using 80 watts at 8 ohms. It has a Shetfield 1230 in it which is a 75 watt speaker.
To be fair, I have gigged this amp a ton over the years and have never pushed the preamp volume past hallway (it doesn’t have a master volume).
I have also ran it into a 4x12, when I was younger and didn’t know about back problems (disconnected the internal speaker) and the volume control was closer to 3.
I don’t think that you said it, but someone else said that solid state amps sound better when pushed almost full. Do you find that to be true? I was always under the impressions that the harder it’s pushed, the more likely it is to break.
I guess that is why I assumed higher wattage=more headroom=less stress on the amplifier.
I know that you are speaking more about volts and how important of a factor that is. I don’t know the output voltage of the Peavey Bandit, but I’m happy to try to measure it if you I can with my multimeter!
With a budget of $200? Actually with the Antek
Hit breakup at 10-15 watts? I listened to a podcast which had a Jensen speaker designer and he said at low levels you get the same amount of breakup as high levels.
Megatrab, the $100 Challenge thread is over 100 pages long. And it was not a dozen people pulling in different directions. This is the normal process given the type of question, starting from scratch. I would like to see a SS amp that is designed to clip the output in a musical fashion, little global NFB, I also think a stiff power supply rather than one that sags a bit like a tube amp is going in the wrong direction. Like it or not we like the sound of tube amps, SS amps can sound good clean and well into overdrive. Getting the edge of breakup sounding good might be a challenge. If that is not a concern, a power amp built to hifi practices might be fine. Speaking of SS (and transformers), the 'Fet version of the JCM800 using LND150 mosfets'.
http://milas.spb.ru/~kmg/index_en.html
Some SS stuff.
https://www.jeanpierrepoulin.com/PDF/transistor.pdf
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No, you don't hit breakup at 15 watts but you hit x-max. Breakup refers to cone moding, which is independent of drive, for the most part. When you hit x-max you suddenly lose motor strength. Its a fundamental property of high sensitivity drivers - in order to have a lot of coil in the gap there isn’t much room for it to MOVE before some comes out of the gap.
Tube or solid state, in order to work within a $200 budget your transformer choices are limited. Antek toroids are the best bang for the buck, barring picking up a surplus bargain somewhere. 20 years ago you could do so quite reliably. Not anymore. For a power trafo that will make 300VDC the 1:1 Triad toroids keep up well. Some of the little (<100 VA) Hammond EIs are also cost effective, but you can’t go turning them around and using them for OPTs, just B+.
Tube or solid state, in order to work within a $200 budget your transformer choices are limited. Antek toroids are the best bang for the buck, barring picking up a surplus bargain somewhere. 20 years ago you could do so quite reliably. Not anymore. For a power trafo that will make 300VDC the 1:1 Triad toroids keep up well. Some of the little (<100 VA) Hammond EIs are also cost effective, but you can’t go turning them around and using them for OPTs, just B+.