Sand-based life forms and other anomalities . . .
However, I must add that the impression of "screaming loud" is important to someone miking a speaker for a recording, and small amps are preferred for this purpose by many pros. When budget constraints don't intrude, use the tube rectifier. I would do so on another design given the chance. And there are less expensive tube rectifiers out there than the types commonly used in most store models that would work fine in a small amp.
Which points to another issue. There are thousands of tubes out there that go begging for buyers at $1 per tube. So it isn't at all necessary to go to semiconductor followers just to get around the need for current in a low impedance output. Take the question of blocking distortion. What is needed isn't a voltage follower (which is an extra and intrusive addition to the circuit), but drive. That's why it's called a driver. Being also a phase inverter doesn't absolve a stage of this responsibility. The 6EB8 will provide all the drive needed by a phase inverter to feed a pair of 12A6s in a PP circuit, and the excursions into grid current slide off the circuit as insignificantly as water off a duck's back. The 6EB8 simply delivers all the current that is needed. And it isn't the only 25 mA tube out there.
I know of a certain hi-fidelity amp in which that combination works just fine. And being hi-fidelity you can be sure that any blocking distortion that reared its ugly head would be immediately noticeable. But it isn't, because it doesn't. And the 6EB8 is feeding a pair of .22uF mylar blocking caps!
My point is this: there may be many ways to accomplish a task in "electronics." But there is only one way to build an "all-tube" amp. And that is to use only tubes for the active elements in the amp.
Yes, ultimately (very ultimately, at the peak of volume) it affects the tone, but the rectifier is not an "active" element.
A voltage follower, on the other hand, is an active element. And is, in the above uses, undeniably an extra gain stage added simply (and unnecessarily) to substitute for providing the output current needed from the stage in the first place.
= My 2 cents on this detail.
Point taken. True. I took the liberty of expressing my sentiments in hyperbole, yes.
Again, granted. These are all valid points. As for the power supply rectifiers, we are making allowances due to the cost of using tubes for this purpose and the relative unobtrusiveness to the output sound. But for a purist, no. The power supply rectifier HAS TO be a tube. Solid state rectifiers don't introduce the needed voltage sag when heavy current is being drawn, and this voltage sag is an important part of the tone that says "screaming loud." But we're building a 2-5-Watt amp here. Screaming loud is ruled out by that criterion alone.
However, I must add that the impression of "screaming loud" is important to someone miking a speaker for a recording, and small amps are preferred for this purpose by many pros. When budget constraints don't intrude, use the tube rectifier. I would do so on another design given the chance. And there are less expensive tube rectifiers out there than the types commonly used in most store models that would work fine in a small amp.
Which points to another issue. There are thousands of tubes out there that go begging for buyers at $1 per tube. So it isn't at all necessary to go to semiconductor followers just to get around the need for current in a low impedance output. Take the question of blocking distortion. What is needed isn't a voltage follower (which is an extra and intrusive addition to the circuit), but drive. That's why it's called a driver. Being also a phase inverter doesn't absolve a stage of this responsibility. The 6EB8 will provide all the drive needed by a phase inverter to feed a pair of 12A6s in a PP circuit, and the excursions into grid current slide off the circuit as insignificantly as water off a duck's back. The 6EB8 simply delivers all the current that is needed. And it isn't the only 25 mA tube out there.
I know of a certain hi-fidelity amp in which that combination works just fine. And being hi-fidelity you can be sure that any blocking distortion that reared its ugly head would be immediately noticeable. But it isn't, because it doesn't. And the 6EB8 is feeding a pair of .22uF mylar blocking caps!
My point is this: there may be many ways to accomplish a task in "electronics." But there is only one way to build an "all-tube" amp. And that is to use only tubes for the active elements in the amp.
Yes, ultimately (very ultimately, at the peak of volume) it affects the tone, but the rectifier is not an "active" element.
A voltage follower, on the other hand, is an active element. And is, in the above uses, undeniably an extra gain stage added simply (and unnecessarily) to substitute for providing the output current needed from the stage in the first place.
= My 2 cents on this detail.
P.S.
One further thought:
A semiconductor in the power supply adds zero thermal noise to the circuit. Because any micro-volt thermal noise that is generated gets drowned when it goes swimming in hundreds of microfarads of filter capacitor.
A semiconductor connected to the signal chain, however, does interject noise into the signal. Put a 100uF cap to ground from there and the signal goes into oblivion with the noise.
And although I agree that everything generates thermal noise, I must now take the opportunity to insist that tubes, as active elements in a circuit, do not introduce the kind of thermal noise that semiconductors do. In a semiconductor, the thermal noise is activated in a solid. This presents itself as a resistance to the flow of signal current, having a big effect on the signal. In a tube, well, you simply don't get convective thermal activity in a vacuum. There's no way for the vacuum to introduce molecular agitation into the electron stream. Period. So the location of control, the place where the electron stream is regulated, is noise-free, because there is no thermal resistance to the flow of electrons.
I know about the quantum noise of plate/screen "decisions." But that isn't thermal noise. And I know about electrons bouncing off of a plate in a pentode. Yes. But the triode has neither. And for some reason, the thermal activity that ejects the electrons from the cathode doesn't very much get reproduced in the signal, because that stream is moving freely through a vacuum when it is controlled and is controlled only by a "hands-off" electric field. Not so in semiconductors.
Bottom line: yes, they do. Semiconductors introduce thermal noise in a way that tubes don't.
That's my story, and I'm sticking with it.
One further thought:
A semiconductor in the power supply adds zero thermal noise to the circuit. Because any micro-volt thermal noise that is generated gets drowned when it goes swimming in hundreds of microfarads of filter capacitor.
A semiconductor connected to the signal chain, however, does interject noise into the signal. Put a 100uF cap to ground from there and the signal goes into oblivion with the noise.
And although I agree that everything generates thermal noise, I must now take the opportunity to insist that tubes, as active elements in a circuit, do not introduce the kind of thermal noise that semiconductors do. In a semiconductor, the thermal noise is activated in a solid. This presents itself as a resistance to the flow of signal current, having a big effect on the signal. In a tube, well, you simply don't get convective thermal activity in a vacuum. There's no way for the vacuum to introduce molecular agitation into the electron stream. Period. So the location of control, the place where the electron stream is regulated, is noise-free, because there is no thermal resistance to the flow of electrons.
I know about the quantum noise of plate/screen "decisions." But that isn't thermal noise. And I know about electrons bouncing off of a plate in a pentode. Yes. But the triode has neither. And for some reason, the thermal activity that ejects the electrons from the cathode doesn't very much get reproduced in the signal, because that stream is moving freely through a vacuum when it is controlled and is controlled only by a "hands-off" electric field. Not so in semiconductors.
Bottom line: yes, they do. Semiconductors introduce thermal noise in a way that tubes don't.
That's my story, and I'm sticking with it.
No need for P-P? I guess we could have just called this the 'Make the best SE amp you can for $100 bucks contest'. I purposely went to P=P to give some variety to the game not because it is louder. The 6V6 at 300V I am using right now is louder than anything I got out of my P-P experiments so far. I also went this route as others may be able to benefit from my endeavors if they decide to go this way. Much more information on doing a little Champ out there than doing a P-P with a 70V transformer.
Mosfets were decided to be OK way back when, I put a number of schematics for all to see with them as follower or PI, neither that supply gain (voltage) or would color the signal to any great extent. It is just as neutral as a resistor as far as guitar goes. As they say, different strokes, if any out there had an aversion to SS then they could pass by any design that uses them.
Lots of $1 tubes out there. All good and wonderful. That is until a design becomes popular and that $1 tube is now a $5 or $10 tube. I decided to use tubes that are not necessarily low buck obscure tubes. I wanted the average person at the end of this contest to get a tube with little effort at a reasonable price. 12AX7, can get them anywhere, 12AU6, 12AQ5, enough out there for any number of builds. And if they become scarce just change the filament transformer and use 6AU6's or 6AQ5's, no shortages of them. Or just run the heaters in series and a resistor in line with the 6AU6 on 12V. I would prefer an amp I help spawn be around in 20 years passed on to another generation.
As far as the rest of your post, I left it out and will not comment on it because I feel it does not show you in the best light. We are all just having a bit of fun here, nothing to take seriously.
I really do not like to disagree with someone, but I cannot accept that a 12AX7 of any kind can be had for a "reasonable" price under about $12 USD. That's more than ten percent of the price ceiling for this "challenge" I have not spent that on the total for all three of the tubes in my design.
And I agree that there are many ways to do things and different people will prefer different things for solutions to their own needs. And there are also many forums for discussing the design of a tube amp, even many other threads in this forum. It happens that this particular thread was started to achieve a particular design goal. If it is wrong for me to draw anyone's attention to that original purpose, then forgive me. I was not aware that such was an offense against anyone's integrity.
But I am somehow also somewhat sensitive to the origin of this "challenge" and knowing how and why it originated have to take exception to several of the things you said.
I, too, could build a modest PP amp. I have done so. But it puts out a bit more than 5 watts, which is what I understood the rules of this game to be. I could redesign it to put out less. But that's only a personal choice. I don't mean to imply that a PP amp is not welcome here. Nothing of the sort, please. I am simply pointing out that since it is not a necessary prerequisite to the achievement of the stated goal, a need to deal with blocking distortion is therefore also not a necessary problem to be solved, either. If you wish to submit a PP amp, by all means do so. If you need to solve the blocking distortion problem, then by all means do so. I have no problem with these things. I am simply pointing out that the original design goal was to build an amp with no solid state devices in the signal chain. If someone other than the OP who created the challenge has changed that requirement, then I don't feel that it is a legitimate change. YMMV. But I haven't seen any evidence that the person who created the challenge has ever restated it as broadly as I'm seeing here.
If we don't have to follow the rules, well, then perhaps I should find other people to play with and other games to participate in. But it happens that one of my designs was savagely attacked and ridiculed in this forum, and this thread was the result of the presumption that a better amp could easily be built at a competitive price.
I happen to disagree with that presumption. And I think it has been soundly defeated by the sum of all the results of those who have participated in this thread. Achieving the goals as originally stated is NOT so easy as was presumed.
Perhaps you did not read the exchanges that led to this thread. If so, then you misjudge me. There is nothing whatever in my recent posts to put me in any bad light. I am, for the most part, merely commenting on the technical issues relevant to an original challenge which was the source of this thread. If I took some amusement at the extent to which this thread has excused the very things that were once belittled in order to set all of this in motion, I think I am perfectly well within the bounds of decency to do so. Thus, perhaps you protest too much about that.
If you have read the exchanges that led to this thread, and you are familiar with its history, then I believe that it is you, sir or madam, who are out of line with your personal attack.
I am merely trying to follow the rules that were set down by the person who originated this "challenge." Yet I seem to be the only one here who thinks that this is important.
Perhaps this is the reason that the original challenger has not been seen in this neighborhood in quite a good many weeks now. I don't wish to presume, but is it possible that having so many of those who jumped into his challenge changing the rules on him until it no longer resembled his original description of the goal led to his disgust with the whole thing?
That's not for me to say. But I will continue to strive to achieve the goal that he established in the first place without regard to the goals that are being pursued here by others. And I am not doing this for the sake of his offered donation to the DIYaudio site, though I would like to see it happen. I am doing this simply to remove the stain from my own reputation, which was unfairly smeared here.
Perhaps you serve a loftier purpose that that. That too, is not for me to say.
I don't understand the statement that implies blocking distortion is not an isue with an SE design. Blocking distortion can be generated in any tube stage with the (im)proper design.
I've done it by accident, iirc George stated he had done it in a preamp stage.
A sufficeintly large cap and RC time constant in a grid circuit with grid current is all that is required. It is topology independent beyond that.
There are several 12AX7s in the $7-$10* range (granted still high compared to the $ menu), if you want a 12AX7 for less than that, go with a 6N2P ($3-4).
*AES, Tube Depot and others Sovtek $9, JJ Spyral Filament $9.75, Chinese $7.95,
I've done it by accident, iirc George stated he had done it in a preamp stage.
A sufficeintly large cap and RC time constant in a grid circuit with grid current is all that is required. It is topology independent beyond that.
There are several 12AX7s in the $7-$10* range (granted still high compared to the $ menu), if you want a 12AX7 for less than that, go with a 6N2P ($3-4).
*AES, Tube Depot and others Sovtek $9, JJ Spyral Filament $9.75, Chinese $7.95,
JJ Electronic 12AX7/ECC83 - $9.75, I splurged rather than use a Chinese one at $7.75. I did a number of other buying decisions that makes it harder to keep in the $100 limit but then I was trying to take the aproach of what would make a good sounding amp. If I saw a schematic for a $100 amp would I buy the parts as listed? I would have sprung for the couple of extra bucks for the JJ rather than the Chineese. And speaking of, did someone mention not needing to buy a chord? That is another $3.15 that I could put towards more features. I would assume everyone can scrounge one up from an old computer but I did not think that was fair game.
As far as the rules of the game, we discussed the parameters. We came up with, SS is ok as long as it is not used to modify the signal, we did not have a 5W limit. It was also decided on a $100 limit rather than the sum that you ask for your amp. That in itself does not seem fair if this was a case of comparing others to your amp. And I agree one of your designs was savagely attacked and ridiculed spawning this challenge. I for one said I had no problem with what you were charging for the amp you delivered. I did say that it sounded like you were whining though, I did not want to bring it up again but... And yes I did read the original exchange. And I do agree with you nothing you said in the previous exchanges had put you in a bad light, not sure why you are starting now.
This challenge was set up as an alternative for people who want to build a small home amp. The rules were formed on the way rather than up front, just the way it worked. As I said I am not here to win a chalange, but if it makes you feel better I will remove the offending device and throw it in the dust bin.
As far as the personal attack on you, I just looked over my posts on the last couple of pages. Could you please point out the attacks, I could not find them myself.
Well....well. Nothing wrong about being passionate. You love, you hate. That's fine by me. I think this 'flame of passion' (hyperbole) has a lot to do with Tubekit being over sensitive about his 'primitive' design. Please take into account the several meanings of the word primitive before taking offense.
Some of us just pointed out the limitations of a 1 tube guitar amp and the fact that you can build a better thing for almost the same money. Not talking about profits here, just an amp for personal use.
I'm cool. I don't care much about what others are doing really: it doesn't mean much to me until I get to hear some audio clips. So what they put inside and outside their amps is not my business. I'm just trying to build a cheap, good sounding amp; I'm sure others are using different approaches to reach the same goal. Anyway, this is a contest. Build yourself what you think would sound best and you will win. You may also win the argument between tubes/SS in the process.
Anything can happen though. We always have to factor in human subjectivity, human weakness, human stupidity, etc. If my design doesn't win it will be because others are deaf or stupid. Or both.
Some of us just pointed out the limitations of a 1 tube guitar amp and the fact that you can build a better thing for almost the same money. Not talking about profits here, just an amp for personal use.I'm cool. I don't care much about what others are doing really: it doesn't mean much to me until I get to hear some audio clips. So what they put inside and outside their amps is not my business. I'm just trying to build a cheap, good sounding amp; I'm sure others are using different approaches to reach the same goal. Anyway, this is a contest. Build yourself what you think would sound best and you will win. You may also win the argument between tubes/SS in the process.
Anything can happen though. We always have to factor in human subjectivity, human weakness, human stupidity, etc. If my design doesn't win it will be because others are deaf or stupid. Or both.
This is my first time checking in for a while, and evidently it's an opportune time. Folks, let's back down from the bickering a bit, and simply enjoy the exchange of creative ideas.
As I explained in a post several pages back, I am currently dealing with my father's terminal illness. My absence has nothing to do with 'disgust'; it has everything to do with real-life demands on my time and energy.
Tubekit, I appreciate your contributions to this thread, and respect your design ideas. But you need to tone down the hyperbole and develop a little thicker skin. It was, after all, your absolute statement about your amp kit being the ne plus ultra of low-cost circuitry which triggered this challenge. I thought that statement was over the top, and several others agreed. In your posts which have followed, I've gained a lot more respect for you than I had originally. You've demonstrated far more expertise and work on practical development than I initially (and incorrectly) assumed.
There are always problems communicating by written posts instead of face-to-face conversation -- nuances are lost, opportunities for clarification are delayed. Sometimes there are language and cultural misunderstandings, e.g. several of costis_n's posts raised my hackles, but I resisted responding reflexively and emotionally. In the grand scheme of things, a perceived insult on the internet about a basement construction project is trivial.
The whole point of this 'challenge' was to be creative, flexible, and most of all, to have fun. This isn't a legal battle, or a military campaign. If the rules drift a bit, that's fine. If the deadline slips, that's OK, too. Let's remember that we're dealing with a hobby, not life-or-death.
I AM dealing with life-or-death, and will be heading back to the hospital as soon as I post this.
Perspective, gentlemen -- take a breath and lighten up a bit.
I switched the pentode to the first position and the triode in back, I do not think I like it as much but my memory of how it sounded may not be as accurate as I like. Kind of a pain rewiring it back and forth to determine the differences (especially with my rats nest), there has to be a better way.
So I started drawing, time to change some wires again.
So I started drawing, time to change some wires again.
Yeah I know, get a life. But the schematic I posted earlier on converting from paraphase to cathodyne bothered me. The schematic I posted bothered me. For some reason I thought it could be simpler and I did not like the phase reversing when going from one mode to the other. So I went back and re-looked at it. Seems one switch was redundant so now only a three pole switch is needed rather than a four pole. I also reconfigured it so that the phase does not flip when changing modes. Not a big deal on the 5D3 and 5E3 but it does matter between the 5B6 and the 5E6 Bassman that uses negative feedback. Might never get used but I like to get it right in case anyone wants to use it.
Nice to see you back, bst. I wish you strength to deal with your troubles and trying times. My father is 90 years old, is very frail, and has recently broken a promise to refrain from humiliating me as his last act on earth. I do understand the kinds of difficulties that can completely dominate ones' every waking moment. I know what it is to be a man of sorrows and acquainted with grief. And to be facing an unpleasant circumstance that can never be reversed or altered once it is set in stone. If I have been a little "testy" lately, please bear this in mind. To think of what I just revealed above is to find myself mentally "digging my fingernails into the palms of my hands". Day and night without relief.
It is also good to hear that you are not "disgusted" and are comfortable with all the changes to your original specifications. Much of my agitation had as much to do with the sense that your original intentions had been simply tossed aside as with the sense that this challenge was any kind of rational response to the claimed shortcomings of my poor man's amp.
Which is somewhat echoed in Kimi's comment above that one could build "a better thing for about the same money," a statement I will have to disagree with one last time (since 2 is not "about the same" as 1), and then let it go. Especially since I rather agree with almost everything else that Mr. Madrid said. My feelings about the origin of the thread aside, its goals and specifications now make a great deal of sense. So long as its purpose is not simply to silence me, I can see it as a worthy one without being false to myself. Suddenly, in a flash of inspiration, I do see the value of opening up the possibilities to a variety of designs outside of the rather confining space of the original concept. And this will remain so even if I do continue to have a visceral aversion to the idea of putting semiconductors in the signal path of a vacuum tube guitar amp as a fix for poor design choices or as a cheap shortcut. I do understand that there are designs which combine solid and vacuum gain stages that produce effects not obtainable with either one alone. And I may even applaud the use of such. In a mic pre or keyboard amp, yes, I just very well might. Perhaps someday I might even be persuaded to see the advantages of a guitar cord that carries no current and reluctantly admit one or more of them into my own circumstances. I grant that it's possible, anyway.
First, I agree that the statement was over the top (even if I have yet to see the evidence that it was also false.)
But more importantly, if I've gotten far enough to have earned your respect as being a person with something of value to contribute to this dialog, then there is no further need for a defense of my integrity. I'll let it rest when I click "Submit Reply."
As for having a thicker skin, let's take a moment to answer someone else's question:
Not to belabor it, but simply because you asked:
Granted, it's subtle. But it's a slap in the face nonetheless. It's a polite euphemism for "you are misbehaving."
I was more direct, true. I said, and only presuming that you knew the whole history of this thread, that you were the one who was "out of line." You admit that you do know it. Pot and kettle time. So there's no reason for everyone to be standing around staring at just me with goggle eyes.
Agreed. Which is why some of us may occasionally feel the need to explain a previous comment at length.
While I'm inclined to just agree without further qualification--after all, it does for the most part express a healthy attitude toward this thread--I can't. From your point-of-view from the starting line, this is, perhaps, all true. From mine, not as much. I saw sales drop to almost nothing after your comment. So it wasn't quite as much "fun" for me back then. I had spent and borrowed considerably to make that little "poor man's" amp available to those for whom it was the only option in their budget at the time. (And still is.) Once people began to realize that they simply could not get something better for less anywhere else, sales began to creep back up.
Not life-and-death, perhaps, but then, each of us, in his own way, is dealing with a life-and-death issue. Every day. Not everyone realizes that fact every day, as you now do.
But I agree. Let's lighten up. May the best man win. And learn something he didn't know before.
May everyone else share his prize to some extent or other.
I'd like to add one more thing...isn't life grand and full of surprises? Who could have known that in a thread about a cheap tube amp one would read such a display of both reasoned and passionate discourses. Hey, I'm glad I did and I'm also glad of being glad when I should instead be bored because there is no music to be heard lately on this thread.
Start tuning up your guitars because there's only two weeks left. Just a reminder.
Start tuning up your guitars because there's only two weeks left. Just a reminder.
"Time's a waistin'" --Snuffy Smiff
WAIT! Did I hear you right? Did you say "two weeks"?
I thought the deadline was tomorrow, October 15.
I was (am) in a panic because I didn't (don't) know when I was (am) going to find the daylight hours (think neighbors) to make recordings, and find the time to draw the circuit, and get it online with a BOM!
Two weeks?!! Are you sure?
(I'll take your word for it but I think I'll check back for confirmation after I record something.)
I just changed my "beater" strings a few minutes ago. Yesterday, I changed the strings on a Martin. I'm digging out my recording mic as we speak . . .
WAIT! Did I hear you right? Did you say "two weeks"?
I thought the deadline was tomorrow, October 15.
I was (am) in a panic because I didn't (don't) know when I was (am) going to find the daylight hours (think neighbors) to make recordings, and find the time to draw the circuit, and get it online with a BOM!
Two weeks?!! Are you sure?
(I'll take your word for it but I think I'll check back for confirmation after I record something.)
Resistors introduce thermal noise too, but we can't leave them out based on that quality alone. I tend to use mosfets as voltage followers late in the signal chain where the signal level is already high. A few microvolts from a mosfet buffer at the output tube's grid where the signal level is tens or hundreds of volts will not be heard.
If the "sand in the signal path" thing does not work for you, don't use it. Easy solution. If it causes heartburn for a few others here, I will rip the mosfets out.
My parents force fed my brothers and I music lessons (and a bunch of other useless things) starting at about age 5. It took a while, but I started liking the lessons after we found a decent teacher. My first guitar and amp came from the music store and the amp annoyed my father so much that it vanished one day. I had an electric guitar and no amp. My father "upgraded" his old Magnavox mono HiFi to a "modern" solid state Sears stereo and I got the old Maggie. It took me about 7 seconds to twist the wires of a guitar cord to the wires in the tone amp and a long career of craziness was born. This was somewhere in the mid 60's. Within a few years I was making tube based guitar amps from scratch out of old TV sets. In high school I even made a few guitar amps using those transistor thingies. Yes they sounded different, especially when cranked. It wasn't a sound that I liked, so most of my stuff used tubes, besided old TV's were free then.
I have made guitar amps, and HiFi amps and a zillion other electronic gizmos ever since using tubes, transistors, and IC chips. I am an electrical engineer by trade having worked for Motorola for the past 38 years. I have learned to set the specifications for a design up front and use the best device for the job in every circuit. I am fully aware that the MAIN criteria for a guitar amp IS tone. There was a period of time back in the 80's when I was a tube guitar amp tweaker and I built and sold quite a few custom amps back then. There was no sand in any of them except a few solid state rectifiers.
As family obligations grew (wife, kids...) I got out of that world and haven't built a guitar amp since, other than a few experiments that were never finished, and a fes amps for my daughters friends in high school. Now that I have ventured back into the guitar amp world, from admitedly a different prespective, I will do what I want and do it my way. I don't expect anyone else to agree with me. Some of my ideas will work and some will suck, but I am not afraid to try anything. The worst thing that will happen is the neighbors call the cops......That isn't new either.
The picture in my avatar.....It came from one of my "experiments". It rocked, put out over 200 watts, and yes contained mosfet followers:
The 833A SE Amp Prototype
That is a matter of opinion. Frankly I am not doing any of this to win a challenge. The 4 tube design I posted only has sand in the power supply. Sag is provided by small filter caps and a barely sufficient power transformer. The bigger amp can be built without the mosfets. I tried it both ways and prefered the way the tone stack worked when fed by a low impedance source (mosfet buffer).
It's doubtful that I will have time to finish either amp. I too have lost my mother and my mother in law this year. I got along with Sherri's parents a lot better than I did my own, and I have made dozens of trips to her hometown (I got back this afternoon) over the last 4 years assisting Sherri in dealing with her mothers terminal cancer. This has put me behind at work and with my Tubelab stuff. The BS doesn't get any easier after the relative passes either. Now it's probate, unhappy relatives and lawyers.
If bang for the buck was the only criteria then it would be real hard to beat the Fender Mustang series. We are all free here to make what we want. If we all wanted the same thing the world would be a pretty boring place. A true tube amp purist tends to shun sand based life forms as well a PC boards often for the same reasons.....because it's always been that way. I tend to accept both.
If you have a capacitor connected between the driver tube and the grid of the output tube, with the usual resistor from the grid to the bias supply (or ground in a cathode biased amp) then your circuit IS succeptable to blocking distortion, also known as "farting out". There are things that can be done to reduce the effect, but it can not be totally eliminated. The usual cures are driver transformers, or a cathode follower feeding the grid directly.
Most HiFi amps are not usually run into clipping. Guitar amps are.
I developed the PowerDrive circuit to eliminate blocking. It has worked well in HiFi applications and shown promise in some guitar amp experiments. The explanation is here, but it is somewhat old. I have learned quite a bit more that I haven't had the time to post:
PowerDrive
It was not my intention to "savagely attack" anyone. That is just not my style. I saw what I thought to be a challenge, and I replied "wanna bet". I have not heard your original amp, and you haven't heard mine (sand free version), but I believe that either one could stand against the other, and the personal preference of the listener (perspective user) would mean more than anything else in choosing a winner.
I was trying to make an amp for one of my daughters friends about 14 years ago. We were tweaking with my Mexican Strat and both agreed that it sounded like S... He returned with his ES335 and absolutely loved the amp.
An awful lot of those DSP things are getting sold......Someone must like them.
Not misbehaving but the goodwill you have achieved in the last little while was being undermined. If you are in a crowd of people with food on your face would you not apreciate someone going, psst, and kind of indicating to discretely brush it off? It took me a bit of though on how to phase it trying not to be harsh and yet to get the message across, tried to be subtle as I could.
Yes you mentioned it a little while ago and I posted my relief when we were corrected and the date was said to be the end of the month, not the 15th. Seem to recall something that it is not all that fixed but not worth the effort to go back and see what was said.
Now, the reason I stopped in, a mistake in the schematic I posted on switching between cathodyne and paraphase, the switch at the top does nothing, it should bypass the 47k resistor and put the supply voltage on the 56k. Sorry for the confusion.
Chaps, at the moment I'm an interested bystander, watching and learning. Don't make me dig out my badge, I really don't want to.
Anyway in the mean time, I'm bodging together a little project using a pre based on the AX84 extreme project with, (sorry Tubekit!), a chip amp power stage. Plan is to convert it once you folks come up with the killer design, but give me something to play with until then.
Keep up the good work!
Anyway in the mean time, I'm bodging together a little project using a pre based on the AX84 extreme project with, (sorry Tubekit!), a chip amp power stage. Plan is to convert it once you folks come up with the killer design, but give me something to play with until then.
Keep up the good work!
Should a guitarist expect voltage from a wire in a magnetic field?
And that's good because I have made a few changes recently and now I can't seem to get rid of some hum that keeps getting louder with each change. Putting things back the way they were doesn't seem to help, either.
I think it was a mistake to put the return jack from the reverb tank right next to the filament transformer. It looked like a nice open spot when I was drilling holes in the chassis but it think my lowest level circuit is now taking a bath in a magnetic field.
The weird thing is that shorting out the resistor in the dry circuit that attenuates the dry bypass going into the tone stack to keep if from overpowering the reverb return at the point where they meet, reduces the hum. But it seems to be coming from the plate of the reverb recovery amp, and it's not above that plate resistor, only below it, so it isn't from the power supply. The return signal from the tank is so small that it appears to get lost in the fuzzy cloud of noise on the scope at 5uA per box vertical deflection (using a 1x alligator clip for a probe), the same indistinct fuzz I see with nothing connected to the probe except that it seems to wiggle a little more, so I'm blind from the middle of that tube on back to the tank output.
Turning down the reverb mixin cuts the hum. Pulling the reverb cables out of their jacks doesn't affect it. I think a reason the attenuation resistor contributes to the hum is that it is a high impedance (470K) back to the 100K volume pot wiper, and when it is shorted, it reduces the impedance of the recovery amp output, . . . but it has that much of an effect? And then the dry signal is three times too loud.
But the source has to be that magnetic field. And there's no obvious place to move these reverb send/receive jacks.
And I did make some recordings this evening, despite the hum. Took me quite a while to get everything hooked up and dialed in, so the experience was a valuable one. And now I can examine the, uhh, "results", yes, that.
It's a good thing there's time to rehearse a bit more and play these things over again in front of an open mic. Yes, it is. A very good thing.
Remember that time when one-by-one everyone in the bar got up and sauntered out and the only person left after about fifteen minutes was the guy with the guitar?
Well, anyway, I just did. I may not ever have seen such a thing, but I just "remembered" it.
Thanks, I'll look around for it.
And that's good because I have made a few changes recently and now I can't seem to get rid of some hum that keeps getting louder with each change. Putting things back the way they were doesn't seem to help, either.
I think it was a mistake to put the return jack from the reverb tank right next to the filament transformer.
It looked like a nice open spot when I was drilling holes in the chassis but it think my lowest level circuit is now taking a bath in a magnetic field.The weird thing is that shorting out the resistor in the dry circuit that attenuates the dry bypass going into the tone stack to keep if from overpowering the reverb return at the point where they meet, reduces the hum. But it seems to be coming from the plate of the reverb recovery amp, and it's not above that plate resistor, only below it, so it isn't from the power supply. The return signal from the tank is so small that it appears to get lost in the fuzzy cloud of noise on the scope at 5uA per box vertical deflection (using a 1x alligator clip for a probe), the same indistinct fuzz I see with nothing connected to the probe except that it seems to wiggle a little more, so I'm blind from the middle of that tube on back to the tank output.
Turning down the reverb mixin cuts the hum. Pulling the reverb cables out of their jacks doesn't affect it. I think a reason the attenuation resistor contributes to the hum is that it is a high impedance (470K) back to the 100K volume pot wiper, and when it is shorted, it reduces the impedance of the recovery amp output, . . . but it has that much of an effect? And then the dry signal is three times too loud.
But the source has to be that magnetic field. And there's no obvious place to move these reverb send/receive jacks.
And I did make some recordings this evening, despite the hum. Took me quite a while to get everything hooked up and dialed in, so the experience was a valuable one. And now I can examine the, uhh, "results", yes, that.
It's a good thing there's time to rehearse a bit more and play these things over again in front of an open mic. Yes, it is. A very good thing.
Remember that time when one-by-one everyone in the bar got up and sauntered out and the only person left after about fifteen minutes was the guy with the guitar?
Well, anyway, I just did. I may not ever have seen such a thing, but I just "remembered" it.