Wigwam Jones
Caesar non supra grammati
(post 5 has "ALL" the amp info figured out and listed by Kegger)
This thread is started at the behest of Kegger, whom I am currently working with (along with Squidward) to build a Compactron-based amplifier at low cost.
It all started a couple months ago, when I found a reference to an old article in Nuts-n-Volts magazine for a Compactron-based stereo amplifier. A 'compactron' is a simple enough idea - in the last days of tubes, GE had the bright idea to keep them alive a little bit longer to compete with transistors by placing the guts of two or more normal tubes inside one glass envelope. So a compactron is a twofer, or a threefer, etc.
As I understand it, a lot of these were used in TV's, as 'sweep tubes' (whatever that is) and as a result, they have a very linear characteristic curve (this is a good thing for music fidelity). They're also dirt cheap, because there were millions made, and because they don't get routinely poached by eBay shoppers looking for tubes for their crunchy guitar amps.
So I bought an old copy of the magazine, gave it to Squidward, and asked if he could help me build an amp. He was interested, got Kegger interested, and the next thing I knew, it was off to the races. Squid would call me every so often and tell me about some new idea that Kegger had to make the unit even more interesting, more powerful, more cool, more...well, you get the idea.
I had no problem with that - Squidward told me that he and Kegger were going to each build themselves one as well, and I thought cool, should be great.
After some time, though, I thought back to the original idea. A pair of 6T9 compactron tubes, a pair of cheap Edcor output transformers and one power transformer, and a handful of parts.
That was the original purpose of the 'other' thread. I wanted to see if anyone was like me - wanting to build the absolute cheapest, easiest to build amp possible, learn about amps along the way, and have some fun. I didn't mention this history in that thread because I didn't necessarily want the design to be a compactron-based tube, just something easy and cheap and bog-standard.
The problem is, as Kegger pointed out to me on the phone, that all the old hands are not going to want to build a crappy amp. They want to help, but they want to build amps that interest them. So that's kind of how that thread went to hell and scared off all the n00bs like myself.
Kegger said hell, let's just do the basic compactron amp, el cheapo style, but with room to mod it after it's done. He even started speaking Klingon to me about PakProtector's bizarre mathematical formulae - yeah, sounded like Greek to me. But he agreed to do the original amp I wanted - with the exception of a more 'interesting' tube, the 6LU8. I'll let him explain why it is better than the 6T9 that the original Nuts-n-Volts article called for (because I don't know).
http://www.nj7p.org/Tube4.php?tube=6LU8
It's like saying you are interested in new curtains and the next thing you know, someone's ripping up your driveway because if you're going to do new curtains, you definitely need a new floor, and if you're going to do that, you probably want to spruce up the paint, and if you're going to all that trouble, the yard should be resodded, and man, look at the cracks in that driveway. Guys, chill. All I wanted was new curtains.
So no harm, no foul, no blame.
But this thread is about the 6LU8 compactron amp for next to nothing in price, easy construction, and nothing else. Anybody wants to add that EL34's singled-ended to a borgwarner 4 speed transmission and a Dana 60 with locker would be the better way to go is going to get a pinch. Start your own bizarre notion thread, this one's mine.
We're going to do this week by week, with lots of photos and explanations and time for people who want to join in to source their parts and tools. That's because I'm broke alla time and I've got nothing for tools - not even a soldering iron. So slow, easy, cheap, and well-documented is what this is all about.
And there you go. Now Kegger can wax philosophical or something.
This thread is started at the behest of Kegger, whom I am currently working with (along with Squidward) to build a Compactron-based amplifier at low cost.
It all started a couple months ago, when I found a reference to an old article in Nuts-n-Volts magazine for a Compactron-based stereo amplifier. A 'compactron' is a simple enough idea - in the last days of tubes, GE had the bright idea to keep them alive a little bit longer to compete with transistors by placing the guts of two or more normal tubes inside one glass envelope. So a compactron is a twofer, or a threefer, etc.
As I understand it, a lot of these were used in TV's, as 'sweep tubes' (whatever that is) and as a result, they have a very linear characteristic curve (this is a good thing for music fidelity). They're also dirt cheap, because there were millions made, and because they don't get routinely poached by eBay shoppers looking for tubes for their crunchy guitar amps.
So I bought an old copy of the magazine, gave it to Squidward, and asked if he could help me build an amp. He was interested, got Kegger interested, and the next thing I knew, it was off to the races. Squid would call me every so often and tell me about some new idea that Kegger had to make the unit even more interesting, more powerful, more cool, more...well, you get the idea.
I had no problem with that - Squidward told me that he and Kegger were going to each build themselves one as well, and I thought cool, should be great.
After some time, though, I thought back to the original idea. A pair of 6T9 compactron tubes, a pair of cheap Edcor output transformers and one power transformer, and a handful of parts.
That was the original purpose of the 'other' thread. I wanted to see if anyone was like me - wanting to build the absolute cheapest, easiest to build amp possible, learn about amps along the way, and have some fun. I didn't mention this history in that thread because I didn't necessarily want the design to be a compactron-based tube, just something easy and cheap and bog-standard.
The problem is, as Kegger pointed out to me on the phone, that all the old hands are not going to want to build a crappy amp. They want to help, but they want to build amps that interest them. So that's kind of how that thread went to hell and scared off all the n00bs like myself.
Kegger said hell, let's just do the basic compactron amp, el cheapo style, but with room to mod it after it's done. He even started speaking Klingon to me about PakProtector's bizarre mathematical formulae - yeah, sounded like Greek to me. But he agreed to do the original amp I wanted - with the exception of a more 'interesting' tube, the 6LU8. I'll let him explain why it is better than the 6T9 that the original Nuts-n-Volts article called for (because I don't know).
http://www.nj7p.org/Tube4.php?tube=6LU8
It's like saying you are interested in new curtains and the next thing you know, someone's ripping up your driveway because if you're going to do new curtains, you definitely need a new floor, and if you're going to do that, you probably want to spruce up the paint, and if you're going to all that trouble, the yard should be resodded, and man, look at the cracks in that driveway. Guys, chill. All I wanted was new curtains.
So no harm, no foul, no blame.
But this thread is about the 6LU8 compactron amp for next to nothing in price, easy construction, and nothing else. Anybody wants to add that EL34's singled-ended to a borgwarner 4 speed transmission and a Dana 60 with locker would be the better way to go is going to get a pinch. Start your own bizarre notion thread, this one's mine.
We're going to do this week by week, with lots of photos and explanations and time for people who want to join in to source their parts and tools. That's because I'm broke alla time and I've got nothing for tools - not even a soldering iron. So slow, easy, cheap, and well-documented is what this is all about.
And there you go. Now Kegger can wax philosophical or something.