Little Sweetie Forum amplifier project

[Curious_George]

12 minutes ago, henry4841 said:

one must remember Russia sent a missile into space before we did. Like a lot of stuff they did they got the info on how to do it from the west in secret. 

Russia could not even build a reliable rocket engine, that is why we beat them to the moon. Plus, we took the smarter German scientists.  von Braun was one smart guy.

[henry4841]

Morning guys, early morning for me. I have been watching one of Roger Modjeski's seminars at the Burning Amp Festival held in San Francisco every year the last couple of days freshening up on tubes and their circuits. Every time I watch any speaker at the Burning Amp Festival I learn something new about audio and electronics. Roger was an audio engineer that once taught at Stanford. Let that sink in, taught at an Ivy League school. In country boy language 'really knew his stuff.' I said knew, past tense,  being he passed away in 2019. He appeared at the BAF twice, 2015 and 2018. I can almost guarantee you will learn something new every time you watch one of his speeches on tube circuits. 

Right at the first of the video he throws out the input cap and ground resistor in the front end from someone's amplifier. Not physically. That is what Maynard and I discussed a few days ago. I see both of them as good insurance but like Roger said not essentially necessary. He had an unconventional way of designing amplifiers as well. Doubling the voltage on the power tube but lowering the current reaching the same dissipation figure recommended in the tube data sheets. He was very successful doing it this way. One of his old used amplifiers brings thousands on Ebay now. When giving one of his speeches in a crowd of engineers and geeks his knowledge and calculations flow like water from his mouth. For anyone wishing to understand tubes and tube amplification better I highly recommend watching his two BAF seminars. He loved teaching best of all of his talents. 

 

 

[henry4841]

Something else I wanted to mention about Roger, he did not like a lot of 2nd harmonics judging by what was said on the video. He wants to cancel it out even in a SET. For those that do not know a SET amplifier as a rule has a good bit of 2nd harmonic, most every one. To me a little 2nd harmonic gives an amplifier some personality. I like it. That is the reason I prefer single ended amplifiers over push pull ones. Do not get me wrong I like PP amplifiers but my preference is single ended. SET tube amplifiers are all single ended class A. This Sweetie amp by Maynard has a lot of personality. There are many like myself that will love the sound of the Sweetie and then there are those, not so much. Same thing about any SET tube amplifier no matter who sells or designs it. Nelson Pass in his First Watt amplifiers builds some personality in each and every one of them. He has stated that he has on a few occasions introduced some 2nd harmonics when there was not enough of it in some of his First Watt designs. The Pass Labs amplifiers, not so much. Different crowd of buyers. I have a SET 45 tube amplifier I throwed a lot of money, for me, into. Tried to build it as best I could without going extravagant. I have heard many times over the years how well it sounds. Mine is not one of my favorite amplifiers. It is a SET but very clean and sterile sounding. Over the years I have wondered why I disagreed with those that praises the sound of the 45 tube. My thoughts at this time in my life is I do not have a trained ear to appreciate the sound the SET 45 tube amp delivers. I believe the praise comes from it's ability to reproduce lets say a violin string accurately. I have very little experience ever hearing a violin and certainly not in my house. I do not know how a good violin is supposed to sound. My experience of music is what I enjoy and what I am use to hearing in a singer of band on a recording and not live music. I do believe I have a pretty good ear on what sounds good for most. My best friend who passed away 2 years ago was paid to work the sound board for the local bands in my area. Bands considered his hearing to be what they wanted their audience to hear. Every time I finished a new amplifier he would come over and listen to it with me and we would discuss what we were hearing. Did not always agree. He preferred the sound of an open baffle full range speaker setup I have over the sound of my big horns. I still use the bass bin of my LaScala's but set a big horn on top of it when I listen this way. The best compliment he could give is when he said I had my system dialed in the way he liked when he worked a sound board. He also toured for a few months with a professional band. Never can remember the name of that group. He had to remind me every time the  subject came up. He only toured with them for a few months. Told me it would have killed him if he stayed much longer. I will not go into the whys but will only say too much of a good thing. At least what one thinks is a good thing when they are young.

 

I say it again, enough rambling from an old man early this morning.  

[henry4841]

Below is the one other time Roger gave a 1 hour lesson at the BAF 2018. You may have to start in at the first since I am in the process of watching it again. He died the next year from cancer at 68 years old. You young guys are living in a wonderful time. When I was 20 years old we did not have videos of a teacher, professor?, that taught at Stanford talking advanced tube circuitry for free on the net. You must realize it cost the parents of kids going to Stanford a small fortune to spend 4 quarters hanging out with this guy and we get to see 2 lessons from him for free. One does not have to have degrees to make it in the electronic world. Companies actually want whoever can the do the best job the fastest. I believe there is a misconception that if you have an electronic engineering degree you will get a high paying job designing circuits when it actuality you will most likely be repairing PCB board rejects from the factory floor. They have the time required to fix and repair a board down pat much like the flat rate book mechanics have at a service center. Like the average time to find and fix a board is 45 minutes. The boss expects you to repair 10.66 of them in a day or you will be looking for another job. The graduates with an electronic degrees that go into designing new products are in the top 5 or 10% of the graduating class. Companies want the best minds doing the designing. 

 

My son that makes the most money of my 4 boys never went to college. Two of my other sons did, one from Auburn and the other from a community college called Troy. The one that graduated from Auburn went on to become a lieutenant commander or possibly commander before retiring from the Navy. But Eric, the one that only went to high school, is making 6 figures and the 1st number is not a 1 selling encryption software to large companies. The company he works for sells the software that the techs working at a large business use to create a unique encryption different from anyone else. They are not like consumers who just buy a mass market for everyone software. If they did that they would be broke into by hackers the very first day. Now he just flies mostly in the USA for business meetings but a few years ago he was flying all over the world teaching the engineers at companies that have bought the specialized encryption software from the co. he works for. As most know the big money is in sales in most any company. He went to India many times. Tells some hair raising stories about the drivers on the road there. Also went to Dubai a few times as well. Said he did not like it so much. Nothing much to do there for the 1 or 2 weeks he had to be there. His favorite place to go to was Singapore. Always enjoyed going there. The point is here he is, without a college degree, he is making big bucks because he gets the job done. He was a computer geek right when computers were making a scene in the consumer market. Could always find him at home in front of his Apple as a teenager. 

 

If one can understand this Sweetie 3 circuit amplifier you will have a good foundation to grow on. I mean really understand what is going on in this amplifier. What every component in the circuit is there for and why. Then you can gradually add more and more circuits into your repertoire. If you spend some time watching Roger's videos and try and soak in all that he is saying you will be on your way for enjoyment in the hobby of amplifiers or possibly more than just a hobby one day if you learn young enough. When he mentions something, a circuit or a new word, that you do not understand do some googling and find the answer to your question. Going to SS from tube is easy since a lot of the info is much the same just using a different active device. All the parts around an active device are there just to make the active device, whether tube or SS, work the best it can. At least as much as the talent of the designer knows how. Mass market amplifiers are now switching over from tubes and transistor to chip amplifiers, class D. But still there are components around that chip to make it work correctly just like a discrete tube or transistor.  

 

https://www.youtube.com/watch?v=1pU3jNquDUo&t=1390s

[henry4841]

Just thought I would add, my boys get their smarts from their mother. My ex and I were like oil and water but no question about her being smart. She went on to become a successful business woman and even got on her picture on the front page of a local circulating magazine last month showcasing her success. Me, I am still just a good old country boy.

[Marvel]

On 9/6/2022 at 3:41 PM, Curious_George said:

Plus, we took the smarter German scientists.

 

Kidnapped you mean? They were held for a few years before being brought to the US. For sure we didn't want the soviets to get them...

[Curious_George]

25 minutes ago, Marvel said:

 

Kidnapped you mean? They were held for a few years before being brought to the US. For sure we didn't want the soviets to get them...

They didn't complain...

[Marvel]

I worked with a German lady who lived not far from the Russian border. She said she left home and literally ran to the west. She told me that 'what else would you expect me to do? I was 16 and the Russian army was 20 miles away.'

 

She was a hoot! Had great stories to tell.

 

Back to the amp...

[Islander]

On 9/6/2022 at 12:41 PM, Curious_George said:

Russia could not even build a reliable rocket engine, that is why we beat them to the moon. Plus, we took the smarter German scientists.  von Braun was one smart guy.

 

Times have really changed.  Now the Russians make all the good rocket engines.  The big ones that NASA uses for the Saturn V, the RD-180 model, come from Russia and cost $23 million apiece, and they get used once, unlike the Space-X boosters.

 

Some time ago, NASA bought 29 of those engines, so even if US-Russia relations are frosty right now, NASA is set for rocket engines for a while.

 

As for the Russian space capsules, according to Chris Hadfield, now retired, but former astronaut, former team leader on the ISS and former launch chief at Houston Space Centre, the capsules are upgraded after most launches, so nearly every flight has the astro- and cosmonauts (there is always a Russian in the middle of the 3-seater, at the controls.  Well, it is their spacecraft.) riding in the most advanced and reliable version of the Soyuz.  They’ve been doing this for a long time, without an accident for decades.

 

One odd thing is that the Soyuz capsule comes down on land, and since it’s not a spaceplane, it falls down and lands where it lands, not always close to the designated arrival site.  In the wilds of Kazakhstan, where it lands, there are nomadic tribesmen who sometimes find it before the rescue team, and strange scenes have ensued.  One time, after the capsule opened, two tribesmen thought it was a boat and couldn’t figure how it was on the prairie, so far from water.

 

Another time, after the space travellers climbed out, one tribesman climbed in and started looting the capsule, grabbing whatever he could pull loose.  Luckily, the rescue helicopter arrived right then.

 

Anyway, the Russians have certainly caught up to the US in space.  You know how the ISS is up high, but it does encounter enough air molecules to slow it slightly, meaning that it has to be boosted higher on a regular basis?  It’s not done by using the little attitude thrusters.  All they can do is keep the station pointed the right direction.  Instead, one of the Russian boosters, after it delivers supplies and/or new crew, pushes the space station until it’s high enough and moving fast enough to stay up in its orbit.

 

About a year ago, during the boosting process, the booster went out of control and its engine continued to fire after it should have shut off, and nearly put the whole space station into a spin.  Luckily, the crew acted very quickly and got things under control.  Everybody in the space biz does their best, but as Chris Hadfield puts it, “What’s the next thing that could kill me?”  This is what astronauts have to think of at all times.  It’s pretty serious business.

[Marvel]

34 minutes ago, Islander said:

 Everybody in the space biz does their best, but as Chris Hadfield puts it, “What’s the next thing that could kill me?”  This is what astronauts have to think of at all times.  It’s pretty serious business.

I need to watch his music video from the ISS again. Great stuff.

[Islander]

11 minutes ago, Marvel said:

I need to watch his music video from the ISS again. Great stuff.

 

Also check out I.S.S. Is Somebody Singing?

 

It’s a music video with Chris on the ISS and Ed Robertson of the Barenaked Ladies, plus a high school choir.  It’s national anthem material in my opinion.

 

 

[Marvel]

That's the one I meant. Gives me goosebumps.

 

@Islander

 

Reposted in the YT video section

[henry4841]

44 minutes ago, Islander said:

 

Times have really changed.  Now the Russians make all the good rocket engines.  The big ones that NASA uses for the Saturn V, the RD-180 model, come from Russia and cost $23 million apiece, and they get used once, unlike the Space-X boosters.

 

Some time ago, NASA bought 29 of those engines, so even if US-Russia relations are frosty right now, NASA is set for rocket engines for a while.

 

As for the Russian space capsules, according to Chris Hadfield, now retired, but former astronaut, former team leader on the ISS and former launch chief at Houston Space Centre, the capsules are upgraded after most launches, so nearly every flight has the astro- and cosmonauts (there is always a Russian in the middle of the 3-seater, at the controls.  Well, it is their spacecraft.) riding in the most advanced and reliable version of the Soyuz.  They’ve been doing this for a long time, without an accident for decades.

 

One odd thing is that the Soyuz capsule comes down on land, and since it’s not a spaceplane, it falls down and lands where it lands, not always close to the designated arrival site.  In the wilds of Kazakhstan, where it lands, there are nomadic tribesmen who sometimes find it before the rescue team, and strange scenes have ensued.  One time, after the capsule opened, two tribesmen thought it was a boat and couldn’t figure how it was on the prairie, so far from water.

 

Another time, after the space travellers climbed out, one tribesman climbed in and started looting the capsule, grabbing whatever he could pull loose.  Luckily, the rescue helicopter arrived right then.

 

Anyway, the Russians have certainly caught up to the US in space.  You know how the ISS is up high, but it does encounter enough air molecules to slow it slightly, meaning that it has to be boosted higher on a regular basis?  It’s not done by using the little attitude thrusters.  All they can do is keep the station pointed the right direction.  Instead, one of the Russian boosters, after it delivers supplies and/or new crew, pushes the space station until it’s high enough and moving fast enough to stay up in its orbit.

 

About a year ago, during the boosting process, the booster went out of control and its engine continued to fire after it should have shut off, and nearly put the whole space station into a spin.  Luckily, the crew acted very quickly and got things under control.  Everybody in the space biz does their best, but as Chris Hadfield puts it, “What’s the next thing that could kill me?”  This is what astronauts have to think of at all times.  It’s pretty serious business.

I've seen the youtube doc on that Russian engine. Watched it twice. I forget what was so special about the engine but it is something special about it and it was built decades ago. 

[Islander]

13 minutes ago, Marvel said:

That's the one I meant. Gives me goosebumps.

 

You must have seen him do Space Oddity.  A spaceman, singing about a spaceman, in space.  The guitar on the ISS is a Larrivee parlour size model, and I just learned that there are two of them on the ISS, so there was a jam in 2018, with two NASA astronauts on guitar, two cosmonauts on flute, and an astronaut on an improvised drum.  Pretty cool!

 

Chris Hadfield - Space Oddity:  

 

 

[Islander]

Back to the amp.  Sorry about that.

[henry4841]

What you guys think of what I came up with for an amplifier chassis. You have to admit it looks solid with wood and thick sheet aluminum. One thing for sure it is one of kind. I bet If I had it my office when I was working all the guys would be drawn to it to take a look. Hillbilly folk art SET tube amplifier. You find things like this In places like Maggie Valley NC. For those that do not know there are no chain restaurants in Maggie Valley. It's where old folks go to vacation to relax and get away from it all. Neat little town nestled in between a number of mountains. I use to like to go around this time of year when the leaves start changing. Busy time for the Smokies. I really like the look. People are doing that real rustic look to old rusty cars. Get it mechanically redone and the insides real pretty but leave the outside alone and just spray some clear over it. I think it is called a rat rod. Is that right? Just a passing fad probably. I would not care to have one. 

 

 

[henry4841]

Guys the test I ran using Arta may be flawed. I have not tested my new signal generator with Arta to see how clean the signal coming out of it is before running it into the Sweetie. If the signal generator has a dirty signal the amplifier is going to to amplify the dirt. I just assumed the generator is clean. Assume nothing when doing any test. I will try and remember to do that sometime today. 

[henry4841]

I think in a past post I called the 6Y6 a pentode when it actually it is a beam tetrode, tetrode 4 pins instead of the 5 pins in a pentode. Interesting history about it's development. Some guys in England built the first pentode and got a patent on the design. Anyone building a pentode tube had to pay the English guys a royalty to do so. The USA guys decided to design a tube that does the same thing as a pentode with just 4 pins and presto we have the Beam power tube. And do not have to pay a patent fee to the English guys. You tech geeks can net it and find the details if interested. I found the history interesting when I read about it years ago. 

[henry4841]

5 hours ago, henry4841 said:

Guys the test I ran using Arta may be flawed. I have not tested my new signal generator with Arta to see how clean the signal coming out of it is before running it into the Sweetie. If the signal generator has a dirty signal the amplifier is going to to amplify the dirt. I just assumed the generator is clean. Assume nothing when doing any test. I will try and remember to do that sometime today. 

I did delete my findings using Arta on the Sweetie yesterday. The reason being is that my new signal generator has too much distortion to give an accurate picture of what the amplifier is doing. I just hooked my generator up to Arta and below is what I found. Way too much internal distortion to use with a harmonic distortion analyzer. My findings yesterday was terrible wrong about the Sweetie. I still have one of those Chinese wonders and I will see how it looks on Arta and possible give an accurate picture of the distortion analysis on the Sweetie. 

 

Pictures are the distortion of the signal generator I used yesterday along with another picture of my setup to use Arta. Laptop with Windows, signal generator, decent external sound card and attenuation box. I still have the plans for the attenuation box for someone to build if interested in playing with the harmonic profile of your builds. As you can see way in the picture too much distortion to use with Arta. 

 

[henry4841]

My other signal generator profile. Harmonics are better along with noise floor but higher distortion number than the new signal generator. New for me that is. 1.42% total distortion and noise in the signal generator. Even a higher number than the other generator .66% but the profile of the characteristics of the signal look better. But neither one is good enough to get an accurate picture of what the amplifier harmonic profile truly looks like. Oh well had fun playing with Arta again. I do have the HP radio frequency generator I use for tuner alignment and I believe it does have an audio frequency output as well. Have to check it at some other time. Probably better than either one of these cheap generators even though it is 30 or more years old. Comparing the pictures of both the generators you can see the new generator has many more higher frequencies distortion inherent in the signal than the $100 Chinese generator. Neither one looks very good for distortion work though. 

 

I do still have what is called a FFT distortion function on my oscilloscope I could use for a general idea of what the amplifier is doing but I am not going to play with it today.