In 2006 we traveled to San Diego during vacations. Visited such nice towns like Solvang, Santa Barbara, old San Diego, staying couple of days in each. On the way back we stopped as well in Long Beach, on Queen Mary ship that serves as a hotel now. Pleasant Valley is quite far from Pleasant Hill, that is in Northern California, near San Francisco. The next time if I go there I will definitely visit you!
I agree with you. But today the best practice for high quality is to draw a PCB on computer then order boards from some company that specializes in making them. However, a single board will cost you more then hundred bucks, but if to order one hundred of them it will be something like ten dollars or less per board. When you have a budget on R/D it is not a problem, but for a hobby or a small company it may be too costly, to order a single board for the first draft of the prototype.
Mine was design of thick film ICs. The first and last project was a microwave movement sensor for security. Then I went to a different town and changed carreer from developer to support engineer then manager of support of railway radio and electronics. Then I changed my career path again, to support computer hardware, then to software development, then to build Internet and Intranet systems. But all that time audio design and singing/playing were my hobbies.
I see the easiest path for newcomers to day is to buy some ready made Chinese amp, then tweak it. However, building from scratch may be more entertaining and rewarding, in terms of self-education.
God bless you Ivey; I wish you good health so we may work together discussing good ideas and practical solutions!
Anatoliy
Well, rats!!!!!!!!!!!!!!!!!!! What about us crusty oldens'?
It's assumed that old farts have the nous to find things out for themselves.
I watched a few episodes of a TV programme called "Grumpy Old Men" before I realised it was comedy, not a documentary. It was composed of lots of "interviews" with blokes > 45 whingeing about, well, everything. I was in complete agreement with them...
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Well I'm not 'old' yet, but I'm practicing the grumpy part in order to be prepared
Anyhow, I have to say how excited I was to see this thread and then pop over to the thread on Wavebourns tower and see Gyrators in a hybrid. I would never have understood what I was looking at before. But over the past weeks and months I've gone in a huge circle of learning. I started with SS Class AB as my first project. Then I went off to learn about feedback, zero feedback and lots of feedback, then I went off to learn about Nelson's designs and their simple (yet complex) approach. Now firmly a Class A advocate I started looking for inspiration from old SS designs like JLH. Then I realized how they all stem out of things the tube guys did years ago. I started to see how nice it was to work with chokes and transformers. Then I started to put things together in my mind - how about a SS equivalent of a choke to load an amplifier stage, how about tubes up front for their linearity. And as the mist started to clear I stumbled on this thread which lead me to the tower and WOW THERE IT IS, gyrators (I'm thinking they are like chokes) loaded onto tubes with SS outputs. I feel like another light bulb just went on. My next big circle of learning is going to start with this Tower. [first I still have to build some simple SS Class A projects to finish the last big learning circle].
Thank you very much you guys !
Anyhow, I have to say how excited I was to see this thread and then pop over to the thread on Wavebourns tower and see Gyrators in a hybrid. I would never have understood what I was looking at before. But over the past weeks and months I've gone in a huge circle of learning. I started with SS Class AB as my first project. Then I went off to learn about feedback, zero feedback and lots of feedback, then I went off to learn about Nelson's designs and their simple (yet complex) approach. Now firmly a Class A advocate I started looking for inspiration from old SS designs like JLH. Then I realized how they all stem out of things the tube guys did years ago. I started to see how nice it was to work with chokes and transformers. Then I started to put things together in my mind - how about a SS equivalent of a choke to load an amplifier stage, how about tubes up front for their linearity. And as the mist started to clear I stumbled on this thread which lead me to the tower and WOW THERE IT IS, gyrators (I'm thinking they are like chokes) loaded onto tubes with SS outputs. I feel like another light bulb just went on. My next big circle of learning is going to start with this Tower. [first I still have to build some simple SS Class A projects to finish the last big learning circle].
Thank you very much you guys !
Hi Bigun;
if you are interested in Gyrator load of tubes, you may consider this thread as well:
http://www.diyaudio.com/forums/tubes-valves/143687-gyrator-question-8.html#post1837303
And this:
http://www.diyaudio.com/forums/tubes-valves/140699-anti-triode-sepp-how-do-best.html#post1778215
if you are interested in Gyrator load of tubes, you may consider this thread as well:
http://www.diyaudio.com/forums/tubes-valves/143687-gyrator-question-8.html#post1837303
And this:
http://www.diyaudio.com/forums/tubes-valves/140699-anti-triode-sepp-how-do-best.html#post1778215
Bigun:
Why don't you tell Wavebourn and I, just how big you plan to make this Class A.
20 watts, 50 watts..., 100 watts even. Because the bigger they are. The hotter they get.
Class A audio amps above 10 watts have there own set of problems that must be dealt with. Heatsink size is the first. Transformers, chokes, regulators, protection, etc.
You looked over WaveBourn thread, and as you seen, he used 30 elect. caps. That is a lot of jouls. It will and can, knock you for a loop.
I have a drawing of a 25 watt Class A. Built in a tower design, similar to Wavebourn's, yet easier to build. Requiring fewer tools and parts.
So give us a yell, if you like.
Take Care
Ivey
Why don't you tell Wavebourn and I, just how big you plan to make this Class A.
20 watts, 50 watts..., 100 watts even. Because the bigger they are. The hotter they get.
Class A audio amps above 10 watts have there own set of problems that must be dealt with. Heatsink size is the first. Transformers, chokes, regulators, protection, etc.
You looked over WaveBourn thread, and as you seen, he used 30 elect. caps. That is a lot of jouls. It will and can, knock you for a loop.
I have a drawing of a 25 watt Class A. Built in a tower design, similar to Wavebourn's, yet easier to build. Requiring fewer tools and parts.
So give us a yell, if you like.
Take Care
Ivey
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O.K. tympani1d:
Wavebourn and I, will not forget you too.
BTW; do you know of Nigel, he is selling several items on eBay Uk. One of the items that he is sell is a PCB package called "PCBCAD30", with the follow up being called "PCBCAD40".
They sell for 15.00 pounds. A small sum, but I wonder if it is any good. You can buy alot of beer for 15.00 pounds.
I ask him to email me a copy; but no reply. So..., do you know any thing about it? Seen it, used it?
Give me yell O.K..
Take Care
Ivey
Wavebourn and I, will not forget you too.
BTW; do you know of Nigel, he is selling several items on eBay Uk. One of the items that he is sell is a PCB package called "PCBCAD30", with the follow up being called "PCBCAD40".
They sell for 15.00 pounds. A small sum, but I wonder if it is any good. You can buy alot of beer for 15.00 pounds.
I ask him to email me a copy; but no reply. So..., do you know any thing about it? Seen it, used it?
Give me yell O.K..
Take Care
Ivey
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Joined 2009
Paid Member
OK, I've done some reading.
First thing I noticed, the 'gyrator' load on top of the first tube in the Tower-III thread - I already invented that a few weeks ago
At the time I was setting up a CCS loaded output and wanted to make it SRPP/Aleph so I pulled a signal from the output to the base of the transistor in order to get some counter-modulation. I used an AC coupling for that. Ok it's not the same and I suspect yours is better. I was looking at something similar at the front end (preamp) and adding a cascode to protect the voltage at the collector - I can see this would lead me to your SVCS, at least 'kind of'. Or more likely I still don't understand your circuits.
I'm very grateful for the knowledge you guys make available.
Anyhow, to give a few more details of my plans.
I had two old linear power supplies given to me, from which I've recovered 4 transformers. Each has a single 25V secondary. I plan to build 4 simple low power Class A amps as I've never done anything other than Class AB. I will not achieve 10W into the load, more like 6W but heatsinking may still be a challenge as I have some off the shelf heat sink to use up and it's not that meaty - maybe a good match to the low power though. It's just for fun, I'm not trying to make 'the final amp' for my desk but to learn some stuff, have fun along the way (I'd go buy new Trafo's for that). It's all SS, I'm not yet ready for glass - but I keep a Continental 6AX4 on my desk to remind me of my future plans.
So, roughly - simple power supply with CLC. Output will be BJT followers (if that's the right language) operated in some kind of PP (i.e. some kind of anti-triode if that's the right term). I'll experiment with some different front-ends. At least one version will be zero global nfb and one will have some global nfb.
As a result of all this I will then be brave enough to look at glass....
First thing I noticed, the 'gyrator' load on top of the first tube in the Tower-III thread - I already invented that a few weeks ago
At the time I was setting up a CCS loaded output and wanted to make it SRPP/Aleph so I pulled a signal from the output to the base of the transistor in order to get some counter-modulation. I used an AC coupling for that. Ok it's not the same and I suspect yours is better. I was looking at something similar at the front end (preamp) and adding a cascode to protect the voltage at the collector - I can see this would lead me to your SVCS, at least 'kind of'. Or more likely I still don't understand your circuits.
I'm very grateful for the knowledge you guys make available.
Anyhow, to give a few more details of my plans.
I had two old linear power supplies given to me, from which I've recovered 4 transformers. Each has a single 25V secondary. I plan to build 4 simple low power Class A amps as I've never done anything other than Class AB. I will not achieve 10W into the load, more like 6W but heatsinking may still be a challenge as I have some off the shelf heat sink to use up and it's not that meaty - maybe a good match to the low power though. It's just for fun, I'm not trying to make 'the final amp' for my desk but to learn some stuff, have fun along the way (I'd go buy new Trafo's for that). It's all SS, I'm not yet ready for glass - but I keep a Continental 6AX4 on my desk to remind me of my future plans.
So, roughly - simple power supply with CLC. Output will be BJT followers (if that's the right language) operated in some kind of PP (i.e. some kind of anti-triode if that's the right term). I'll experiment with some different front-ends. At least one version will be zero global nfb and one will have some global nfb.
As a result of all this I will then be brave enough to look at glass....
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I suggest you look up "Zenkido" article on Google, it is 2 PDFs. It describes very basic hybrid amplifier with MOSFET (source follower) output and some interesting ideas (most notably: Pass CCS) combined. 10W is easily doable, anything more than that and you're likely to end up with blown transistors like I did
I think that output stage is a great starting point to which different voltage amplification stages could be attached - you don't have to go the
"Aikido" route, you could start with a simple common cathode VAS first and then expand on it (or use solid state, as initially planned). Granted, Class A is inefficient, but is also the easiest to set up (when follower topology is used) and easiest to understand.
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I don't drink an alcohol, so I can buy one and let you know, is it good or not.
I paid for PCBCAD40 on eBay 5 days ago, but still no message from the seller.
Should I remind him?
All items are sent out straight away and marked as despatched on ebay.
Regards NIgel
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