I am not looking for a kit, moved past that hangup.
The L1 then be less cost as one input transformer, supplying heaters and B+. Not saying a no go, just mention it because previously brought up.
As for point to point, wires make more sense as I can trace them easier. Have you ever installed a FI harness onto an engine? Simply go wire by wire or trace by trace, I am not seeing the difference. I have also done other wiring, including diagnostics which I find fun (apparently normal people loath electrical diagnostics).
Not saying no or arguing, just trying to gain understanding and have a discussion. 🙂
Since it is open source, where is the BOM, please?
The BOM can be found by reading the schematic...
Not sure which post "L1" refers to. I designed the Modular Amp 1 to make excellent sound on a budget - the last time I built one for someone, the build cost was about 950$CAD for a 25W RMS of triode power - a stereo amp with automatic grid bias.
Monoblocs would cost an extra 300$ or so because you need two power supplies and two biasing systems.
The one transformer that supplies your heaters and B+ will cost a lot more than a VPT230-1090 and that SMPS, plus you get the added bonus of DC heaters 🙂
As for going wire by wire, trace to trace vs circuit board: Here's virtually the same amplifier using PCB vs point to point: The PCB is far easier to work with 🙂
Not sure which post "L1" refers to. I designed the Modular Amp 1 to make excellent sound on a budget - the last time I built one for someone, the build cost was about 950$CAD for a 25W RMS of triode power - a stereo amp with automatic grid bias.
Monoblocs would cost an extra 300$ or so because you need two power supplies and two biasing systems.
The one transformer that supplies your heaters and B+ will cost a lot more than a VPT230-1090 and that SMPS, plus you get the added bonus of DC heaters 🙂
As for going wire by wire, trace to trace vs circuit board: Here's virtually the same amplifier using PCB vs point to point: The PCB is far easier to work with 🙂
Since I just saw your other thread about OPTs, and noticed EL84 mentioned, You might be interested in my Little Miracle amp instead of the Modular Amp.
Lower power, but less money and less complicated. Cathode bias by CCS.
TL783 are out of stock but LM317 can work instead.
https://www.diyaudio.com/community/threads/the-little-miracle-pcb.373177/
Lower power, but less money and less complicated. Cathode bias by CCS.
TL783 are out of stock but LM317 can work instead.
https://www.diyaudio.com/community/threads/the-little-miracle-pcb.373177/
I will be bluntly honest since kind of touched on it. You were the first person to respond, back on 6 February. Now that I have spent countless hours on the L1 and post a BOM for review, then suggest this. Almost seems suggesting the BOM is worthless. Then, find out have to do many hours building a BOM is even more off putting. I have mentioned numerous times looking for about 10 watts in this thread, so makes me even more wonder the purpose, though I have a very hard time seeing folks care (I have attachment disorder because of being emotionally abandoned and all forms of abuse by my biological mother), instead, often see it the other way. [Side note. Working on this as I rather not be single all my life. Being an INTJ I already come off as cold.]
This is not to say I wouldn't, need to be shown this is a better design, my logic is superior to emotions. I have not seen any specifications on distortion, separation, dampening, output power, etcetera.
By the way, I am intrigued by the compactness, neat. 🙂
What does this mean?
What is the difference?
Hi Adriel,
Just for the sake of it, have a look at this:
http://www.r-type.org/articles/art-003f.htm
10+10W, very simple, schematic, BOM, performance figures including distortion, uses cheap tubes, instructions for building including chassis etc. Made by very reputable company, Mullard.
Regards,
Jose
Just for the sake of it, have a look at this:
http://www.r-type.org/articles/art-003f.htm
10+10W, very simple, schematic, BOM, performance figures including distortion, uses cheap tubes, instructions for building including chassis etc. Made by very reputable company, Mullard.
Regards,
Jose
How is it simple with the additional circuits for inputs and tone controls, plus additional tubes? Just curious, maybe simpler in another way.
My other concern is looks to be designed for 78 record player, same for the pre amplifier. Furthermore, neither have RIAA equalization.
Please note it has 3 tubes per channel, not 5. Every ECL86 has a high u triode and a power pentode inside.
The design has high gain, yes, but no RIAA equalisation. It does include tone, balance and volume control. Passive tone control requires extra gain to compensate the loss. If you do not want the tone controls, just remove it, then you can reduce the gain increasing feedback and by other means.
From the description:
"Sensitivity
The sensitivity of the basic amplifier for an output power of 10W is 2.3mV without feedback and 23mV with feedback. The sensitivity of the complete amplifier, including tone controls, is 210mV.
"
The main reason I pointed to this project is that it is cheap and includes description of everything, from BOM to chassis build.
The design has high gain, yes, but no RIAA equalisation. It does include tone, balance and volume control. Passive tone control requires extra gain to compensate the loss. If you do not want the tone controls, just remove it, then you can reduce the gain increasing feedback and by other means.
From the description:
"Sensitivity
The sensitivity of the basic amplifier for an output power of 10W is 2.3mV without feedback and 23mV with feedback. The sensitivity of the complete amplifier, including tone controls, is 210mV.
"
The main reason I pointed to this project is that it is cheap and includes description of everything, from BOM to chassis build.
Thanks. The compactness is why I called it the Little Miracle - it was a miracle I was able to make it all fit in a 100mmx100mm footprint.
CCS = constant current source.
LM317 is a 37 volt regulator, TL783 is a 125V regulator.
Since you've asked for BOM of these (you're the first one since I posted the designs actually), I'll assemble one.
Do you want a list of parts and values or a specific parts BOM made through a place like LCSC?
Example
1 x 300R 1/2W resistor vs 1 x VO MO1/2WS-300Ω±5%-ST52
or
2 x 12V Bidirectional TVS diode vs 2x P6KE12CA
I'm inclined to make a BOM in the first style because it frankly doesn't matter who makes the 300R resistor or what composition it is as long as it fits. Same for the TVS diode example.
CCS = constant current source.
LM317 is a 37 volt regulator, TL783 is a 125V regulator.
Since you've asked for BOM of these (you're the first one since I posted the designs actually), I'll assemble one.
Do you want a list of parts and values or a specific parts BOM made through a place like LCSC?
Example
1 x 300R 1/2W resistor vs 1 x VO MO1/2WS-300Ω±5%-ST52
or
2 x 12V Bidirectional TVS diode vs 2x P6KE12CA
I'm inclined to make a BOM in the first style because it frankly doesn't matter who makes the 300R resistor or what composition it is as long as it fits. Same for the TVS diode example.
How then is it a substitute?
My thinking also, though since I was/am going to build a L1, provided the link. Also, what one person chooses might not be the same as someone else. In other words, if you want to make one, recommend doing the first style.
It's a substitute because the highest voltage expected across it is about 30V. I use TL783 for the extra margin but it's not strictly required, and the only situation the Little Miracle will have a 30V cathode voltage is when using EL86 or 6P43P tubes in triode mode.
I overspec and overbuild my designs because they are more robust that way.
I had a tube arc over in a Modular Amp on power up which was strange to me because I had been using it for hours earlier in the day. Oh well, sometimes tubes die.
The arc lasted about 3 seconds, and the main fuse blew. I replaced the tube and the fuse and voilà! Working amplifier again. No blown parts because they are designed to take that type of overload.
A normal tube amp OPT might have failed from the overload, too - Another reason why I continue to use my unconventional "OPT" design of interleaved power toroids for trioded sweep tubes.
I overspec and overbuild my designs because they are more robust that way.
I had a tube arc over in a Modular Amp on power up which was strange to me because I had been using it for hours earlier in the day. Oh well, sometimes tubes die.
The arc lasted about 3 seconds, and the main fuse blew. I replaced the tube and the fuse and voilà! Working amplifier again. No blown parts because they are designed to take that type of overload.
A normal tube amp OPT might have failed from the overload, too - Another reason why I continue to use my unconventional "OPT" design of interleaved power toroids for trioded sweep tubes.
So what is it using for power supply?
I had a bit of a relapse, so mental clarity is basically non-existent...
So then what does one do if want to play LPs after the 1950s?
Then back to where we are with having to design a feedback loop when there is no information on doing this, plus, don't have the tools for such.
What makes it cheap?
By the way, the EL84 tubes I mentioned earlier are now in Frankfort German Post.
My brain is not working at all today... So what is the purpose of this part?
I have not seen it in other tube builds.
I did also, notice instead of 3 watt resistors I went with 5 watt. Also, I live in a desert.
Wow we.
It replaces the typical resistor so you can set the current precisely and match the current of the pair.
I did some looking on the website, what about a stereo instead of six tubes, four tubes? http://www.r-type.org/articles/art-007.htm
Or go the other way and have eight. 😛 http://www.r-type.org/articles/art-008.htm
This is the most specifications I recall being specified for an amplifier.
My bad, I forgot to count the rectifier tube, because I I only use silicon for rectifiers. 7 tubes total, 3 per channel + rectifier 🙂
Most LP players include equalisation pre-amps these days I'd expect. Not an expert on that subject though.
ECL86 and EF86 can be bought for a very small price. But many of the options you have been looking at, like that Audio Note or Tubelab's SPP are also cheap. The OPTs are in any case the elephant in the room.
Great, we now have defined the output tubes, I will stop talking about ECL86, one variable less 🙂
EL84 is a very nice tube to work with, easy to drive, plenty of reasonable OPTs to choose from.
That's a single-ended design, you probably can get 3W out of it, not more. Nothing wrong with that if you have the right speakers (high sensitivity). Too low power for my taste 🙂
That one is one of the classic topologies:
EL84 output stage
ECC83 Phase inverter (LTP style)
EF86 (triode connected) for voltage amplification.
I think the EF86 is an overkill, the ECC83 has plenty of gain to be able to be driven from a typical line output voltage. But removing the EF86 will require also modifying the global negative feedback loop, because it is connected to the EF86.
I would not go for this one myself, I'm not a fun of the ECC83 used to drive output tubes. I would use SPP, or Koda's blocks. I seem to recall he uses a 6F12P, pentode triode strapped for voltage amplification and the triode as a Concertina (split load) phase splitter. That can easily drive a pair of EL84s.
I also would like to note that there is nothing magic with negative feedback network, and they do not burn speakers if one is careful. First of all, you never connect a speaker to the amp for the first time. You always use a 50W 8ohm resistor, therefore any potential instability won't harm the speaker. You tune everything, and only connect the speaker when you see a very nice sinusoidal signal in the 8 ohm resistor after applying the nominal input signal. You do not need an expensive oscilloscope for that, just a PC sound card a resistor divider and a decoupling cap to be able to see the output signal. You can use the sound card as signal generator as well, REW software, for example, will handle all of that.
Having said that, having a nice oscilloscope is great. But it is expensive.
Not any I have seen. Plus, I might be crazy enough to build one.
This looks to have the circuitry in the pre amplifier, maybe what it was assuming? http://www.r-type.org/articles/art-155.htm.
While on the topic, does this have the RIAA circuit? http://www.r-type.org/articles/art-162.htm
I am sorry I was not clear. In the beginning, I was informed 10 watts be plenty and given a couple of tubes, ECL86 was not on that list for some reason. I am fairly set on the L1, though the Elektor Electronics really got me thinking. Sometimes we have to say goodby to our first love because not a great match. 😛 (Being silly.)
I was being somewhat silly. If it was a must to practice a build or two, I do that and use it in the workroom with headphones; not going to take up a lot of space and don't need stereo for background, just nice.
Does that mean a great design?
What does LTP style mean?
About 500mV input, if that makes a difference.
Mind me asking why?
Okay.
Appreciate knowing this. The resistor to enable the circuit to complete, right?
How do you see a wave with these bits? I thought a screen be required?
I have no clue what you just said...
Jose, tried finding the answer, instead find a number of triodes driving EL84s, including Dynaco amplifiers, weird. You think be an answer out there, guess have to rely on you for an answer, was hoping to remove one.
Here are some examples: https://www.yoursoundmatters.com/best-turntables-with-built-in-preamp/
You are right, that one is a dedicated pre-amplifier circuit (no power stages), and it includes RIAA circuitry indeed.
No, it does not. They say that it is designed to be used with a record player with crystal pickup. I'm not an expert, just did some googling, looks like crystal pickups (the older type, modern are magnetic pickups) just need a high impedance input, which this amp supplies. It is nothing more that a two-valve amp, using ECL82 (ECL86 cousin), with passive tone control circuitry at the input.
The topology does not necessary guarantee a great design. You can make a great design with many different topologies, and also can completely screw up any of them. When I say "classic" I mean that it is used a lot. A topology does not include the specific of tubes, or transformers etc. That is my definition, others may have a different opinion. Let's try an example:
Topology: Voltage amplifier + concertina phase invertor + ultralinear push-pull stage + global negative feedback.
Design using the above topology: Tubelab's SPP
ECC83 and it's cousins 12AX7/6N2P are low current triodes with big internal plate resistance. Those are great for voltage amplification (u ~100), but not optimal to drive power tubes. Will they work? Yes, they will, especially with EL84 and 6V6 output tubes, which are notoriously easy to drive. Will I design my amp using ECC83 to drive the output tubes? Nope. A 12AT7 would be a much better compromise, plenty of gain and current to drive an output stage. There are many, many options out there.
A push-pull requires input signals with different polarity (or phases, depending how people name it). Therefore you need some kind of circuit that takes your input signal and generates two outputs, one with the same polarity as the input and the other with inverse polarity. Those two signals are fed to the push-pull stage.
LTP stands for Long Tailed Pair. There are other styles to achieve the same result, for example Concertina ( also named Cathodine, split load). This is very well explained here:
http://www.valvewizard.co.uk/cathodyne.html
http://www.valvewizard.co.uk/dcltp.html
http://www.valvewizard.co.uk/acltp.html
Yes, you should never operate a tube amplifier that uses output transformers without load. It can damage the output transformers or tubes. You use the big powerful resistor in the early stages of testing, when you do not know, for example, if your amp is oscillating due to wrong polarity supplied to the feedback circuit, or parasitic oscillations, some tubes, especially the ones that were designed for radiofrequencies, not audio, can be prone to oscillate at very high frequencies. Using a resistor for load instead of a speaker allows you to detect and fix those potential problems before you plug a real speaker.
Just in your computer screen, just like this (this is REW software BTW):
REW is a piece of computer software that can use a sound card to a) Measure a signal at the sound card line input, including "oscilloscope" function, as shown in the screenshot above, and b) Generate a signal with given frequency and amplitude oon the sound card line output. You can use that signal as a reference for your amplifier, instead of using a CD or record player output, the reason being is that it is much easier to check for things when using a perfect sinusoidal signal in the input at a given frequency than looking at random waveforms from real music.
There is a very good writeup here: https://www.diyaudio.com/community/threads/how-to-distortion-measurements-with-rew.338511/
Always remember, you have to condition an amp signal before sending it to the sound card, you can see the example in that thread. The yellow 8ohm resistor is the one I mentioned above being used instead of a speaker.
REW website: https://www.roomeqwizard.com/
It is free and runs on Windows/Mac/Linux.
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Concrete is quite conductive. Back in 1959 I lived in Boloxi Mississippi and we had an enclosed concrete porch with a refrigerator outside. This was back in the day when a lot of houses still had wiring with two prong unpolarized plugs. If you weren't wearing shoes and touched the refrigerator, you got a shock, a big one!