Same on reverb
Stuff sits for awhile then buy after one or 2 price reductions.
Everybody uses in ears or modelers.
So mountains of stuff to grab.
Peavey did a bunch of 4x10 bassman copies.
Also a good deal just buy the whole amp.
Like the 90's when a Marshall JTM was 500 to 900 bucks
you could buy a used traynor for 45 bucks and its the same circuit.
And the traynor had better hammand transformers.
Bought atleast 3 of them with toasted tubes.
And would just buy chinese EL34's from Mesa to reload them
I find your anecdote fun I guess, but not particularly helpful. In fact, most of your comments are more confusing than helpful.
If distortion starts at 15 watts (even if it isn't audible), then what would be the purpose of 100 watt amplifier?
I don't down tune. I don't play doom. I've never used a 1x12 cabinet that was "fart city". Obviously more speakers will increase the volume. Are you offering to transport and carry it?
Using giant stacks to play a local bar is not only silly, undoubtedly will come with the label "douche bag". That just isn't practical or necessary for any gig. The "I need it for my tone" excuse reflects more on a lack of talent/technique than anything.
I know this thread is long, but its almost like you were reading a different thread where someone said "I need be unreasonably louder than every band in the entire city and have so many speaker boxes that I have to carry in so that my back will be so messed up I won't even be able to perform" which is in fact not what this thread is about.
I know that I started this thread asking for help, but I was pretty specific about wanting to build a solid state amp. I also never set my budget at $200. I just said that transformers alone would be at least that much. I did also point out later that I could buy a used Boss Katana for under $300 which has a power amp in which goes straight into their 100 watt Class AB power amp, which also has output options for 50 watts and 1 watt.
If I wanted to build a tube amp, I would probably just build it from a kit offered by MojoTone or Ceriatone. It would be insane for a novice to try to create a PCB layout and then order them (most places I've seen have a minimum order of 5 for PCBs). I would build it on turret, tag, or eyelet board. I would buy the specific transformers for the specific tube amp.
Rebuilding or repurposing an old non-functioning amplifier does sound like fun, but it also sounds WAY above my current skill level. Its also not something I am interested in doing at the moment. If I had a kit, I can build it with the parts included and source the readily available parts it doesn't come with. I would love to rebuild an old amp at some point, but I wouldn't even know where to begin.
The reasons I thought a solid state amp would be the better choice mostly comes down to cost, but also it will definitely be easier to build.
I think I have enough information on here to make it happen. I'll make a new thread about it as it comes along.
If I wanted to build a tube amp, I would probably just build it from a kit offered by MojoTone or Ceriatone. It would be insane for a novice to try to create a PCB layout and then order them (most places I've seen have a minimum order of 5 for PCBs). I would build it on turret, tag, or eyelet board. I would buy the specific transformers for the specific tube amp.
Rebuilding or repurposing an old non-functioning amplifier does sound like fun, but it also sounds WAY above my current skill level. Its also not something I am interested in doing at the moment. If I had a kit, I can build it with the parts included and source the readily available parts it doesn't come with. I would love to rebuild an old amp at some point, but I wouldn't even know where to begin.
The reasons I thought a solid state amp would be the better choice mostly comes down to cost, but also it will definitely be easier to build.
I think I have enough information on here to make it happen. I'll make a new thread about it as it comes along.
I did just find out that there is a guy on the GroupDIY forum that is selling boards for the Orange CR60/CR120
Orange CR60/CR120 power amp boards
It doesn't have all the parts like what comes with a kit, but I bet that I can source all of the part somewhat easily. I just need to get the right power supply.
Here is the schematic the same user shared
I haven't studied the schematic against the one from eBay but here is that one too
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If your speaker hits x-max (or x-lim) at 15 watts at 82 Hz, it hits the stops at 60 watts at 164 Hz and 240 watts at 328 Hz. And that second harmonic is stronger than the fundamental - even before any frequency shaping in the amplifier. The 100 watts still makes it louder.
The transformers for a small tube amp typically start at $200 - if you buy ones made for the purpose. You get away cheaper only if you cheat and use things other than what they were made for. For SS at 100 watts, the one you need is $58 (400 VA Antek). The $85 600 VA certainly won’t hurt anything.
No, a novice shouldn’t build a home brew PCB for a tube amp. Point to point with solder-lug terminal strips is the way to go. It can be made safe and reliable. The same cannot be said for solid state - you NEED a PCB for the majority of it, even if you run the output pair(s) P-t-P on the heat sink. SS at a high level of reliability isn’t necessarily easier. For best reliability and proper thermal tracking it really should be all on one board, and engineered together with the heat sink. If you do a chip amp that’s absolutely required. Tacking a bunch of wires directly to the pins and making a rats nest is a recipe for an amp that quits or starts a fire the first time it is accidentally dropped. Novice layouts often don’t work well with chip amps - they are more difficult than they appear just looking at a schematic. Add that to the fact you’ll need to bolt it to a flat on one side heat sink that‘s 4x8”, with 2 to 3 inch fins.
https://www.antekinc.com/as-1t300-100va-300v-transformer/ $42
https://www.tubesandmore.com/products/transformer-fender-output-hot-rod-deluxe-and-blues-deluxe $59.95
Not quite a small tube amp, about $100.
On a SS amp, a PCB is not needed although the cost of one is reasonable. Could always buy a board for a design that is promising and could be modified. Back in the day we built amplifiers etching our own boards and there was a fair amount of blank empty spaces on them, no need to cram everything in a tight spot. On early amp chips, I can attest to them being good power oscillators. Mind you I was a teenager then and have learned a little since then. If the SS amp clipping is a no-no, maybe modify one that has a protective circuit and rather than just clamp when the outputs are in danger maybe utilize it as a sort of compression limiter? Mind you, you could always make a circuit to sit before the amplifier and adjust it to limit before clipping occurs.
https://www.tubesandmore.com/products/transformer-fender-output-hot-rod-deluxe-and-blues-deluxe $59.95
Not quite a small tube amp, about $100.
On a SS amp, a PCB is not needed although the cost of one is reasonable. Could always buy a board for a design that is promising and could be modified. Back in the day we built amplifiers etching our own boards and there was a fair amount of blank empty spaces on them, no need to cram everything in a tight spot. On early amp chips, I can attest to them being good power oscillators. Mind you I was a teenager then and have learned a little since then. If the SS amp clipping is a no-no, maybe modify one that has a protective circuit and rather than just clamp when the outputs are in danger maybe utilize it as a sort of compression limiter? Mind you, you could always make a circuit to sit before the amplifier and adjust it to limit before clipping occurs.
Understandable, just trying to save money while presenting something that (if not burned) has a good chance of success and even superiority. Note that "build from someone's kit" does not guarantee success, unless of course that kit has been vetted by multiple positive reviews, then more likely will be a success for you as well.
You seem to be fully enamored with the "chip amp" approach for electric guitar amplification. Since I've been suggesting large old transistor iron with big discrete output devices and the tube amps - I cant seem to compete with the made up mind. So I'll take my bow, good luck to you and perhaps another reading the thread recognizes the efficacy / $ for guitar amping of the used crap I presented here.Here is the schematic the same user shared
@jjasniew I want to say thank you for your contributions and that I am not completely sold on using a chipamp, but they are the most readily available.
I would love to build an amplifier based on discrete components, but since everyone is saying that its a bad idea to build one anything except a PCB, then I have to go with what is available to me.
I would love to build an amplifier based on discrete components, but since everyone is saying that its a bad idea to build one anything except a PCB, then I have to go with what is available to me.
Thanks for the links. I will save those for the future!
Could that power transformer also power a tube preamp stage or would I need more power?
I would be happy to modify an existing circuit, especially those not meant for guitar. I would very much like to try an amp that utilizes current feedback or a way to lower damping and more reaction between the output and the speakers.
Having a circuit before the amplifier is probably going to be the best idea. I've been thinking about that too. Compression/limiting, a gain stage that's made to be pushed by a preamp (like a phase inverter), and EQ (either fixed or to simulate presence and resonance if its not possible to actually manipulate negative feedback).
I am ordering TDA7194 PCBs so I guess that will be my first one.
If you’re worried about difficulties in making a PCB for a discrete amp, it’s even more of a necessity with a chip amp. I guess you figure you can just buy a kit? The problem with SS kits is they never put out the power they say they do. You may end up with a 25-50W amplifier when it’s advertised as “100”. Unless you know up front what it will put out on a given TRANSFORMER, and that it won’t be running the chip within an inch of its life.
There is artwork (ie, gerbers) floating around for the Apex amplifiers. Fully discrete, use generally available parts, and within reason, scaleable. You could take something like the 500W PA amp and run it on +/-53V, and make a bulletproof 100W/8R. JLC is cheap enough where the shipping will be more than the cost of the 5 boards (But still cost less than say, Sunstone).
There is artwork (ie, gerbers) floating around for the Apex amplifiers. Fully discrete, use generally available parts, and within reason, scaleable. You could take something like the 500W PA amp and run it on +/-53V, and make a bulletproof 100W/8R. JLC is cheap enough where the shipping will be more than the cost of the 5 boards (But still cost less than say, Sunstone).
The preamp usually uses about 10% of the idling power in a tube amp, usually less voltage than the output tubes need. Normally there is just one transformer. I have not added current feedback to an amp yet, maybe the others? The TDA7294 looks interesting, hope it is an original and not a knock off.
Current feedback to an amp - you mean “transconductance strapping”. In general it works, fairly easy with chip amps and most regular “Two stage plus followers” transistor amp. Easy to try out for yourself and see if you like the result. It makes a high output impedance, where gain in proportional to speaker impedance. It can be emulated in the front end, giving the ability to model the low end response of more than one speaker (not limited to the voicing of the one you have). Which is better? The jury is out, and will probably end in a mistrial.
Interesting.
That said, all (EBay board, Orange clone, DIYAudio members) are using the same schematic: the one suggested in datasheet for simple and bridged TDA 7294.
Just compare them, so here winner is the best made PCB.
Meaning: for any given configuration (simple or bridged respectively) all will put out same power, sound same, etc.
All are using +/- 40V supplies which I already mentioned is the important parameter.
King of Techs Enzo used to say: "the amplifier is just that thingie between power supply and speaker"
Only difference is that bridged one puts out twice the voltage do is more suitable for 16 ohm speakers, everything else stays the same.
Russian page with the chip with current feedback.
https://datagor.ru/amplifiers/chipamps/86-usilitel-madfeedback-1-tda7293.html
Found it from this page, could be more nuggets in the thread, also speaks of knockoffs.
https://www.diyaudio.com/community/threads/optimizing-tda7294-output.226437/page-46
Not too much information.
https://another-electronics.blogspot.com/2008/12/tda7294-dc-servo-amplifier-current.html
A comment.
I built up a similar circuit and it oscillated badly.
Turned out there were 2 problems.
1/ Feedback resistor needs a very short path as tracks have inductance and cause instability.
2/ I had just used a gain of 10 and the amp needs at least a gain of 22 to be stable.
It must have a good sized heat sink on the amp.
Also it needs 3 power rails, +,- and zero volts or it will probably die.
And two more.
https://www.thanksbuyer.com/tda7294-2-x100w-current-feedback-audio-power-amplifier-board-27331
freestompboxes.org/viewtopic.php?t=19361
https://datagor.ru/amplifiers/chipamps/86-usilitel-madfeedback-1-tda7293.html
Found it from this page, could be more nuggets in the thread, also speaks of knockoffs.
https://www.diyaudio.com/community/threads/optimizing-tda7294-output.226437/page-46
Not too much information.
https://another-electronics.blogspot.com/2008/12/tda7294-dc-servo-amplifier-current.html
A comment.
I built up a similar circuit and it oscillated badly.
Turned out there were 2 problems.
1/ Feedback resistor needs a very short path as tracks have inductance and cause instability.
2/ I had just used a gain of 10 and the amp needs at least a gain of 22 to be stable.
It must have a good sized heat sink on the amp.
Also it needs 3 power rails, +,- and zero volts or it will probably die.
And two more.
https://www.thanksbuyer.com/tda7294-2-x100w-current-feedback-audio-power-amplifier-board-27331
freestompboxes.org/viewtopic.php?t=19361
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