Cold bios for the out put tubes is quite normal in a harp amp in my 5E3 (or it was when i started) I hav a pair of 6l6's cold biased so as to only out put 20 watts max as I hav a 25 watt speaker in there i don't wana blow up, trying to make it sound jus like ( or at least close to) big red. although trying to make a 12ax7 sound like a 6sl7 is hard might hav to change over to octals, what I need is portability
and here's a real rats nest for ya
and here's a real rats nest for ya
Attachments
Very interesting tube switcher for comparing tubes:
https://www.youtube.com/watch?v=VkjVvTRP1h0
Interesting that only one had a good low noise rating.
What do people think of the sound differences?
https://www.youtube.com/watch?v=VkjVvTRP1h0
Interesting that only one had a good low noise rating.
What do people think of the sound differences?
It's time to wake this thread up from it's long sleep.
As this challenge was getting under way I figured out that my fulltime engineering career was on life support with an unknown remaining lifespan. All the engineers that were my age were disappearing, worked to the point of quitting, forced into a situation that couldn't be rectified and fired, or just laid off.
I decided in 2011 that I would leave south Florida when the end came. We bought some land in rural West Virginia that contained a derelict mobile home, cleared the garbage and overgrowth from the property and made the mobile home safe and secure enough for storage.
Sherri and I both lost the last of our parents in 2011. We spent nearly a year each cleaning out their houses and finding homes for their lifetimes of collected "stuff". It was this awakening that led us to the realization that we both had far too much "stuff" AND we would need to move what we kept over 1200 miles. How much stuff????? Come on, I had over 100,000 vacuum tubes and about a ton of transformers. Really.....do you know how much it would cost to have a commercial moving company move it all.....stuff had to go, and fast. Sherri and I gave away, sold, or tossed out about 3/4's of our stuff, and began to move the "good stuff" into the mobile home in West Virginia, one Honda load at a time. This was noted in posts 1080 and 1081.
I began taking on all the tasks at work that most other engineers refused, and picking up the slack by doing the work of two guys who were laid off. This extended my corporate life expectancy quite a bit, but left little time for tubes.
In 2012 it became obvious that my time was short, so we had met with a home builder to have a new house built on our property adjacent to the mobile home. There was about a year of prep work that needed to be done up front, by us including the removal of an abandoned house that contained asbestos, septic tank removal and replacement, land clearing and grading, and last but far from least, convincing Comcast, AEP, and Frontier to move a power pole.....
Some of our "stuff" followed us up here on every trip we made. It was stashed in the mobile home.
In 2013 I got an official letter from the CEO of Motorola.....it said that I could sign the papers and lay myself off for a rather large sum of money, OR wait a few weeks and be laid off with NO money.....DUH, what a choice. I signed the papers. My exit date was postponed 3 times during which most of my friends WERE laid off. Yes, all the old timers gone.
I March of 2013 I left Motorola after 41 years, 3 months, and 1 day. At that time there were two people in the building who had been there longer than me.
We finished the last or our responsibilities, and set the wheels in motion for construction of our new house. In June we put our house in Florida up for sale and drove north in the first of what was going to be 3 26 foot rental trucks full of "stuff". We were unloading that first truck in West Virginia when we got the call. Our house in Florida had sold and we had to be out of it by July 1....are they nuts. No they have CASH.
What does all of this have to do with guitar amps, and this thread???? Well I had two amps working and a third was working before I blew it up. When we had to clear a house in 3 weeks, all that stuff just got thrown into boxes, moved to WVA and thrown into one of 3 places. No clue where anything went.
It is now 2015, we have been living in our new house for 6 months, and I am in the process of building a new lab. In Florida everything was stuffed into a 10 X 10 foot room, lab, listening room, cabinet shop, I even rebuilt an engine and a transaxle on the same workbench where the Tubelab amps were designed. Here I have a 2000 square foot basement.
Sherri and I have adopted a new hobby. We call it "box shopping." we go to one of the storage locations, open a random unmarked box of "stuff" and figure out what to do with the contents. Well, we opened a random box, and there it was. Amp 1.4 from this challenge, just as it was last seen somewhere in about 2012. The Tolex had peeled from the cold, but the chassis was still stuck in the cabinet just as it was when I tossed it into a box over 3 years ago.
Well, what do you think happened next.....carefull power up to check for damage??? No way, plug it in and stand back. Gee, it still works, and sounds kinda like I remember. OK, but not awe inspiring. So I got a pair of Vice Grips and ripped the chassis out of the cabinet, flipped it over and started modding the $#*& out of it. YES, I like it....still not done until I see some smoke though.
The first schematic was posted back in post #1021. I made some changes, and noted all the component values and put the "final" schematic in post #1279. I made a wooden cabinet in post #1200, and put a picture of the half finished amp in post #1253. It must have been tossed into a box shortly after that, because that is exactly like I found it.
I plan to continue tweaking on this amp until I get it into a state that I would use it daily. Why? because, at this point I have no other guitar amp. I sold or gave them all away before moving.
If there is any interest, I'll post the progress here, or in a new thread. I have modded it a bit, so now it's Amp 1.5, and I have already modded it some more since those pictures were taken. Right now it has stunning clean tones, but it doesn't have enough gain to crank yet. Still tweaking.....I will post a new schematic when I'm happy with it.
Yes, as threatened back in the thread somewhere, I stuck in the mosfet PI. It really fixed the amp up. The self split output stage wasn't clean and only made 1.9 watts. Now the output stage can make 4 watts at 2% distortion.....until you push it.
Somewhere in a box near me, are two more amps. One of them made about 15 watts and rocked! The other....well I squeezed it a bit too hard and let the smoke out.......
As this challenge was getting under way I figured out that my fulltime engineering career was on life support with an unknown remaining lifespan. All the engineers that were my age were disappearing, worked to the point of quitting, forced into a situation that couldn't be rectified and fired, or just laid off.
I decided in 2011 that I would leave south Florida when the end came. We bought some land in rural West Virginia that contained a derelict mobile home, cleared the garbage and overgrowth from the property and made the mobile home safe and secure enough for storage.
Sherri and I both lost the last of our parents in 2011. We spent nearly a year each cleaning out their houses and finding homes for their lifetimes of collected "stuff". It was this awakening that led us to the realization that we both had far too much "stuff" AND we would need to move what we kept over 1200 miles. How much stuff????? Come on, I had over 100,000 vacuum tubes and about a ton of transformers. Really.....do you know how much it would cost to have a commercial moving company move it all.....stuff had to go, and fast. Sherri and I gave away, sold, or tossed out about 3/4's of our stuff, and began to move the "good stuff" into the mobile home in West Virginia, one Honda load at a time. This was noted in posts 1080 and 1081.
I began taking on all the tasks at work that most other engineers refused, and picking up the slack by doing the work of two guys who were laid off. This extended my corporate life expectancy quite a bit, but left little time for tubes.
In 2012 it became obvious that my time was short, so we had met with a home builder to have a new house built on our property adjacent to the mobile home. There was about a year of prep work that needed to be done up front, by us including the removal of an abandoned house that contained asbestos, septic tank removal and replacement, land clearing and grading, and last but far from least, convincing Comcast, AEP, and Frontier to move a power pole.....
Some of our "stuff" followed us up here on every trip we made. It was stashed in the mobile home.
In 2013 I got an official letter from the CEO of Motorola.....it said that I could sign the papers and lay myself off for a rather large sum of money, OR wait a few weeks and be laid off with NO money.....DUH, what a choice. I signed the papers. My exit date was postponed 3 times during which most of my friends WERE laid off. Yes, all the old timers gone.
I March of 2013 I left Motorola after 41 years, 3 months, and 1 day. At that time there were two people in the building who had been there longer than me.
We finished the last or our responsibilities, and set the wheels in motion for construction of our new house. In June we put our house in Florida up for sale and drove north in the first of what was going to be 3 26 foot rental trucks full of "stuff". We were unloading that first truck in West Virginia when we got the call. Our house in Florida had sold and we had to be out of it by July 1....are they nuts. No they have CASH.
What does all of this have to do with guitar amps, and this thread???? Well I had two amps working and a third was working before I blew it up. When we had to clear a house in 3 weeks, all that stuff just got thrown into boxes, moved to WVA and thrown into one of 3 places. No clue where anything went.
It is now 2015, we have been living in our new house for 6 months, and I am in the process of building a new lab. In Florida everything was stuffed into a 10 X 10 foot room, lab, listening room, cabinet shop, I even rebuilt an engine and a transaxle on the same workbench where the Tubelab amps were designed. Here I have a 2000 square foot basement.
Sherri and I have adopted a new hobby. We call it "box shopping." we go to one of the storage locations, open a random unmarked box of "stuff" and figure out what to do with the contents. Well, we opened a random box, and there it was. Amp 1.4 from this challenge, just as it was last seen somewhere in about 2012. The Tolex had peeled from the cold, but the chassis was still stuck in the cabinet just as it was when I tossed it into a box over 3 years ago.
Well, what do you think happened next.....carefull power up to check for damage??? No way, plug it in and stand back. Gee, it still works, and sounds kinda like I remember. OK, but not awe inspiring. So I got a pair of Vice Grips and ripped the chassis out of the cabinet, flipped it over and started modding the $#*& out of it. YES, I like it....still not done until I see some smoke though.
The first schematic was posted back in post #1021. I made some changes, and noted all the component values and put the "final" schematic in post #1279. I made a wooden cabinet in post #1200, and put a picture of the half finished amp in post #1253. It must have been tossed into a box shortly after that, because that is exactly like I found it.
I plan to continue tweaking on this amp until I get it into a state that I would use it daily. Why? because, at this point I have no other guitar amp. I sold or gave them all away before moving.
If there is any interest, I'll post the progress here, or in a new thread. I have modded it a bit, so now it's Amp 1.5, and I have already modded it some more since those pictures were taken. Right now it has stunning clean tones, but it doesn't have enough gain to crank yet. Still tweaking.....I will post a new schematic when I'm happy with it.
Yes, as threatened back in the thread somewhere, I stuck in the mosfet PI. It really fixed the amp up. The self split output stage wasn't clean and only made 1.9 watts. Now the output stage can make 4 watts at 2% distortion.....until you push it.
Somewhere in a box near me, are two more amps. One of them made about 15 watts and rocked! The other....well I squeezed it a bit too hard and let the smoke out.......
Attachments
Very nice George! I've just dug mine out as well. I had a friend who was given a new guitar as a gift and also just found his wife is pregnant and I decided he needs a nice amp as a baby shower gift. I don't like half of what I did on the first try so I'm completely redoing my amp, including things like a MOSFET phase splitter and buffer. I've also got a few construction tricks up my sleeve to hopefully keep the total cost of amp and speaker/cab under $200.
There are two half finished work benches in here now. I got all the wood cut before the cold and rainy stuff came. I will have plenty of indoor time in the coming months to work on the lab.
The lab I had in Florida evolved over 35 years. When I first built it I the 70's I was making guitar amps, music synthesizers and large but wimpy "home computers." The PC, Apple II and TRS 80 were not yet invented. Throughout the 80's the computer stuff (and computer based music) took over the lab. I never had the room to deal with two large projects simultaneously.
Now I plan to have three separate dedicated workspaces. There will be a space for tube amps, guitar and HiFi, analog synthesizers, and computer stuff....haven't I been here before?
Sometimes a new shiny object will take over your mind, and reroute priorities. In this case it is an old and not so shiny object....Amp 1.4.
Ever hear the term "circuit bending?" Wikipedia says:
Circuit bending is often practiced by those with no formal training in circuit theory or design, experimenting with second-hand electronics in a DIY fashion. Inexpensive keyboards, drum machines, and electronic children's toys (not necessarily designed for music production) are commonly used. Haphazard modifications can result in short circuits, resulting in the risk of fire, burning, or electrocution.
I did this kind of stuff with guitar amps radios, and whatever we could find as a kid. A ham radio guy and mentor once told me that you would not blow anything up by poking around in a circuit with a capacitor, so I tried it, and kept experimenting. I did blow stuff up, and I still do.
NOTE, all the circuits I played with as a kid were tube circuits since it was the 1960's and the capacitor in question was probably a .05 uF non polarized paper cap. I had already learned that electrolytics will explode.
Well, last night I tried some random "circuit bending" with my little amp. The difference is that now I understand what I am doing. Well, positive feedback can make for some rather unusual sounds....More poking around today.
I have a Fluke 5205A with your name on it -- good from DC to 100kHz. Can't lift it myself.
Usually that's how I make prototype boards. I was unlucky enough to find out that my first two laser printers used toner that was "not compatible with the transfer process". The old HP LaserJet 4L used "high temp" toner that only worked if you superheated the iron on the kitchen stove first. Atypical of my luck with HP products, it lived for 20 years! I got a cheap Brother laser printer, and found the same issue. I gave it to my daughter and got a cheaper Canon which works good.
For SMD boards that require good detail, I sometimes use the photographic method with pre-sensitized boards.
For one off super quick simple stuff just draw our circuit o the board with a Sharpie and etch. Be prepared to fix a few open runners.
Not sure what I would do with a 120 pound high voltage source, but I could think of a few interesting experiments. Sherri and I both decided to cease dragging things home that we didn't really need, but if I am ever in New Jersey.....
Cool user name......unfortunately we used that name for a particular project manager at work. If he inserted himself into your project, he became a "series resistor to the flow of progress."
I spent the morning tinkering with the amp some more. I still haven't found the magic combination that will allow super nice clean tons, and still get nasty when cranked. The front end doesn't quite have enough gain. When I plug in my "Hammer of Thor" (DiMarzio pickups) it rocks quite well, but the $50 swap meet Squire Strat is clean with everything turned up all the way.
Tonight, I plan to move the volume pot to the right one stage and test some more.....
Maybe the right answer is to add a 5th tube.......
This simple circuit doesn't have a tone stack, just a single knob tone control. It isn't like any other control I have met, and I'm not quite sure where it came from. I think I found it in a vintage amp design, then warped it a bit. It will see some more tweaking before it's done. Yes lifting the .01 uF from ground does boost the gain a bit, not as much as I want.
The schematic as it was 4 years ago is in post # 1279.
I added a split load PI between the triode and the 32ET5's. It is wired up pretty much in the standard way, except there is an LND150 mosfet where the 12AX7 goes. I found this one day when I physically stuffed two mosfets into the 12AX7 socket on a guitar amp I made years ago. The gain stage didn't sound tube like, but the PI passes for tube sound since it has no gain either way.
Wasn't Me,,,
And Dang!!
Its nice to see George back isn't it? Lot of water under the bridge since this thread started!
Maybe some new idea's will pop up as well!
