Actually I have shared a picture of populated boards. Here it is again, while making music.
Should I make another thread somewhere else?
I have stated that Folsom is not in possession of a device that can measure exactly how low the distortion is, but it could be 100x better than a stock EC7293 - based on simulation. What's more important, really, is that it has error correcting feedback and that is a marvel to which I feel should be appreciated. It does very nice things for high frequency phase.
The prices are cheaper than other items that have similar amounts of work into them. I didn't really want to directly compare with DIYA projects, but would point out the popular Mod86 costs more (actually a fan of Tom and his work, we've chatted a little, cool guy). The pricing for these boards includes a lot of support. There are many projects on here that may be sold at give away pricing, but they are by older more established people. If I'm being honest they've made it harder for younger designers that want to contribute but don't have the stability many more decades can bring.
There are no fancy parts in particular on this amplifier. Perhaps you consider Dale RN resistors fancy? They can certainly be swapped out. The capacitors needed for full power are not of any sort of "audiophile" variety, but are higher voltage than often seen in DIY & good spec. It could be possible to use very large snap caps, that would make the boards enormous, and not affect the price much either way. Nothing changes the fact that all of the suppliers lean towards more limited amounts of higher voltage capacitors.
As far as complex setup, the feedback section needs a stable voltage in order to work correctly. A consistent recommendation on the solarcell approach is in the works; but the battery works very good and for a long time.
Thank you for your comments. I do understand a desire for as much information as possible, and wish that I could include a nice set of graph from a very expensive piece of equipment. But what I have is a track record of selling a pretty good number of a very simple amplifier project, the DIY7297 & Antipole. People still grab some PCB's now and again. Some people use it as their summer amp because tubes and class A are too hot, others use it year round, some have made it into an all-in-one digital to amp receiver, etc.
Should I make another thread somewhere else?
I have stated that Folsom is not in possession of a device that can measure exactly how low the distortion is, but it could be 100x better than a stock EC7293 - based on simulation. What's more important, really, is that it has error correcting feedback and that is a marvel to which I feel should be appreciated. It does very nice things for high frequency phase.
The prices are cheaper than other items that have similar amounts of work into them. I didn't really want to directly compare with DIYA projects, but would point out the popular Mod86 costs more (actually a fan of Tom and his work, we've chatted a little, cool guy). The pricing for these boards includes a lot of support. There are many projects on here that may be sold at give away pricing, but they are by older more established people. If I'm being honest they've made it harder for younger designers that want to contribute but don't have the stability many more decades can bring.
There are no fancy parts in particular on this amplifier. Perhaps you consider Dale RN resistors fancy? They can certainly be swapped out. The capacitors needed for full power are not of any sort of "audiophile" variety, but are higher voltage than often seen in DIY & good spec. It could be possible to use very large snap caps, that would make the boards enormous, and not affect the price much either way. Nothing changes the fact that all of the suppliers lean towards more limited amounts of higher voltage capacitors.
As far as complex setup, the feedback section needs a stable voltage in order to work correctly. A consistent recommendation on the solarcell approach is in the works; but the battery works very good and for a long time.
Thank you for your comments. I do understand a desire for as much information as possible, and wish that I could include a nice set of graph from a very expensive piece of equipment. But what I have is a track record of selling a pretty good number of a very simple amplifier project, the DIY7297 & Antipole. People still grab some PCB's now and again. Some people use it as their summer amp because tubes and class A are too hot, others use it year round, some have made it into an all-in-one digital to amp receiver, etc.
I think Nick suggests that you should build a full unit and give it to folks to test and give their opinions. Some third party reviews would work wonders for adoption.
I built a DIY7297 + Antipole and I am very satisfied. Would have joined the group buy, but I have too many projects in the pipeline, so will probably just get it later.
I built a DIY7297 + Antipole and I am very satisfied. Would have joined the group buy, but I have too many projects in the pipeline, so will probably just get it later.
Same for me.
I have assembled many TDA7293 in the past as single, dual parallel and even up to four devices in parallel. They all sounded pretty good but were all a little missing in the upper frequency range, missing the little sparkle at the top end. Mind you, that was most likely due to the design/implementation of these cheap Chinese boards. Tom proved it with the Modulus86 at the time, compared to standard LM3886 designs.
120$ for a stereo PCB set is not inexpensive BUT if the amplifier sound is truly great than it is well spent money.
All the best!
Do
Destroyer OS, I fully agree with you on all your points above.
It is interesting that you mention Tom's work on the Modulus86. He was able to turn an average chipamp into a great amp by working out the details of a very tidy implementation, and he documented and published his results every step of the way. It wasn't an easy start for him neither. He had to fight common myths and quasi religious anti class-D crowds. But he had the numbers to prove it, and as soon as people starting building his amp, he built traction for his products and has finally (I hope) reached cruising speed.
You might not need to have the testing equipment in-house, you can talk to Tom and have him run the tests on your amp (it is a service he provides after all)
In the meantime provide data such as input impedance, total gain, etc... (I know the main ones are covered already in your post)
Give as much info as possible and eye candy is always welcome
What Sorinv has advised might not be a bad idea, build a loaner amp that you would circulate around, lots of people have done it, and with great results.
Just to make things clear, I do not feel that the price is high, just that it is not in line with the information the DIY crowd needs in order to pay that kind of money.
Regards,
It is interesting that you mention Tom's work on the Modulus86. He was able to turn an average chipamp into a great amp by working out the details of a very tidy implementation, and he documented and published his results every step of the way. It wasn't an easy start for him neither. He had to fight common myths and quasi religious anti class-D crowds. But he had the numbers to prove it, and as soon as people starting building his amp, he built traction for his products and has finally (I hope) reached cruising speed.
You might not need to have the testing equipment in-house, you can talk to Tom and have him run the tests on your amp (it is a service he provides after all)
In the meantime provide data such as input impedance, total gain, etc... (I know the main ones are covered already in your post)
Give as much info as possible and eye candy is always welcome
What Sorinv has advised might not be a bad idea, build a loaner amp that you would circulate around, lots of people have done it, and with great results.
Just to make things clear, I do not feel that the price is high, just that it is not in line with the information the DIY crowd needs in order to pay that kind of money.
Regards,
as a lurker here, i would also suggest coming up w/plans & instructions for a conventional power supply for the 9v feedback section, as well as battery and/or solar. i, for one, am interested in neither of those. at the end of the day, i want something i can just plug in, turn on, and forget about. i don't want to have to replace batteries, unless it's something like every 5 years, or so. and i am not sure solar would be adequate, unless it could be powered by low-level room lighting.
ymmv,
doug s.,
still needing to get busy on my 7297 amp builds...
ymmv,
doug s.,
still needing to get busy on my 7297 amp builds...
sorinv thank you for the kind words
Indeed, the stock TDA7293 is ok but lacks a full picture. The EC7293 doesn't sound anything like it. The 7293 is just a slave to the specialized input & feedback.
Nick, I need to point out the Mod86 is what you say, a chipamp turned into a great amp. But it's class AB servo controlled, not classD. You might be thinking of Bruno P, on classD. (We read stuff on DIYaudio, constantly)
While the EC7293 does have low THD (how low not known), the feedback of this amplifier has memory distortion about as close to zero as you can get. That linear distortion figure isn't equated in a typical harmonic distortion figure - it isn't additive in such a way that just a THD measurement can express it. My point being is that a lack or gain of a THD measurement doesn't explicitly define the sound of the amplifier. So I hope that can be taken into consideration while looking at this project.
Doug, the solar power would be a turn key solution if you put a solar source inside of the amplifier. I'm working on a compact solution. And I will report ASAP. I just got some in the mail to test.
As much as I want to send out a demo amplifier, I don't have private payback-free money this time. I will if I can, but right this minute I cannot.
Indeed, the stock TDA7293 is ok but lacks a full picture. The EC7293 doesn't sound anything like it. The 7293 is just a slave to the specialized input & feedback.
Nick, I need to point out the Mod86 is what you say, a chipamp turned into a great amp. But it's class AB servo controlled, not classD. You might be thinking of Bruno P, on classD. (We read stuff on DIYaudio, constantly)
While the EC7293 does have low THD (how low not known), the feedback of this amplifier has memory distortion about as close to zero as you can get. That linear distortion figure isn't equated in a typical harmonic distortion figure - it isn't additive in such a way that just a THD measurement can express it. My point being is that a lack or gain of a THD measurement doesn't explicitly define the sound of the amplifier. So I hope that can be taken into consideration while looking at this project.
Doug, the solar power would be a turn key solution if you put a solar source inside of the amplifier. I'm working on a compact solution. And I will report ASAP. I just got some in the mail to test.
As much as I want to send out a demo amplifier, I don't have private payback-free money this time. I will if I can, but right this minute I cannot.
Ok, so everyone has not been into the battery in particular. Folsom is working on a solution that uses LED lights, the basics of PCB are just about worked out. I will have to test the solar cells with the LED of choice.
I've already got some solar cells. They basically only respond to warm light color. Initial test with a single LED desk lamp thing can make them hit voltage, so it should be reasonable to get plenty from a Festoon bulb.
The battery option will still exists, and will feature a very convenient extra transistor to make sure your speaker won't see even a handful of mv DC once the battery dies. (wasn't a "problem" before, but now it's got a double step so you can relax twice as much)
I've already got some solar cells. They basically only respond to warm light color. Initial test with a single LED desk lamp thing can make them hit voltage, so it should be reasonable to get plenty from a Festoon bulb.
The battery option will still exists, and will feature a very convenient extra transistor to make sure your speaker won't see even a handful of mv DC once the battery dies. (wasn't a "problem" before, but now it's got a double step so you can relax twice as much)
Nearly got it wrapped up, and will start a new thread that carries over names.
Question if anyone chimes in... The PSU board will have a mains filter on it (120/230v).
Would people like to see terminals like these on it (they're cheap, only need 2 per amp):
But it is also possible to use something a bit fancier that *might* have better conducting materials (a reasonable assumptions since they have considerably more conductivity for high voltage and current):
The levers compress the wire. They're pretty neat, but they are like $8~and $6~ instead of $2~. (You would need 1x $8~, 1x $6~, and 1x $4~ per amplifier)
The ones I really wanted to use have copper in the material and are big screws, but I'd have to do a big group buy outside of this to get them custom ordered... That is possible but I doubt it'd happen real have.
Video of them at work
Question if anyone chimes in... The PSU board will have a mains filter on it (120/230v).
Would people like to see terminals like these on it (they're cheap, only need 2 per amp):
An externally hosted image should be here but it was not working when we last tested it.
But it is also possible to use something a bit fancier that *might* have better conducting materials (a reasonable assumptions since they have considerably more conductivity for high voltage and current):
An externally hosted image should be here but it was not working when we last tested it.
The levers compress the wire. They're pretty neat, but they are like $8~and $6~ instead of $2~. (You would need 1x $8~, 1x $6~, and 1x $4~ per amplifier)
The ones I really wanted to use have copper in the material and are big screws, but I'd have to do a big group buy outside of this to get them custom ordered... That is possible but I doubt it'd happen real have.
Video of them at work
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You should keep it at a standard lead spacing like 5.00 or 5.08 and this would allow us to use something of your choice? I usually use the terminals that use compression but screw type
An exemple would be :
1729160 Phoenix Contact | Connectors, Interconnects | DigiKey
But everyone uses whatever they like in the end.
Do
An exemple would be :
1729160 Phoenix Contact | Connectors, Interconnects | DigiKey
But everyone uses whatever they like in the end.
Do
They need to be 15A for the safety ground, so most average ones are ruled out for 120/230v. (voltage being another concern)
Also I want 12ga to fit so that compatibility with IEC inlets and such is simple. It should be as easy as connecting some left over 12ga from a DIY power cord to the PCB, then the transformers leads itself will be used on the other side. It is possible to use different ones, but I prefer a congruent look for this one section. Smaller copper based ones are used to connect secondaries, DC output, and all connections on the amplifier boards (if you want to use them, these holes are compatible with appropriately sized wire).
I'll check on lead spacing to see if I can work it for easy pitch compatibility. The board is tight on space in this section.
Also I want 12ga to fit so that compatibility with IEC inlets and such is simple. It should be as easy as connecting some left over 12ga from a DIY power cord to the PCB, then the transformers leads itself will be used on the other side. It is possible to use different ones, but I prefer a congruent look for this one section. Smaller copper based ones are used to connect secondaries, DC output, and all connections on the amplifier boards (if you want to use them, these holes are compatible with appropriately sized wire).
I'll check on lead spacing to see if I can work it for easy pitch compatibility. The board is tight on space in this section.
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Yes, but not all of the connectors will require that 15A rating.
Another exemple :
0395443006 Molex, LLC | Connectors, Interconnects | DigiKey
I really don't mind the other connectors, just saying
Thanks
Do
Another exemple :
0395443006 Molex, LLC | Connectors, Interconnects | DigiKey
I really don't mind the other connectors, just saying
Thanks
Do
The ones you specified, but specifically the more expensive one.
You could also use fast tabs .250 ?
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