Banana Jack Amps: No-Solder, All-Tube Guitar Amp Kits

[tombaker]

Did you take length into consideration when designing this amp? And/or portability?
I understand the buyer/builder would have to provide their own chassis but how long does the signal chain measure? Seriously?
I feel like some design elements have been overlooked in favour of banana plugs. They aren't that good.

[Perrow]

I trust my own judgement.

I haven't looked at your product yet, but from what I've read here I wouldn't let myself or anyone I love near it.

R.G.  is a trusted member here, and I think I speak for almost every member of this community when I say that if he says a product is flawed, you'd better think twice before disregarding the advice he's giving you.

[merlinb]

Careful, if you listen to RG long enough you'll never get anything done, because you'll be too busy wringing your hands. Sometimes you just have to do it. 

(The IEC connector in a box is, however, a deathtrap).

[bool]

I thereby declare ... this thread is going bananas!

[Perrow]

Careful, if you listen to RG long enough you'll never get anything done, because you'll be too busy wringing your hands. Sometimes you just have to do it.  

 (The IEC connector in a box is, however, a deathtrap).

True and true,  and I guess true.

[Luke51411]

To the guy in the $600 banana suit? C'mon!

[slacker]

I would at least make the signal path plugs and power ones a different size, that makes it a bit harder to plug yourself into the mains. I also count about 30 connections, points of failure, between input jack ground connection and mains earth, that can't be clever.

[merlinb]

I would at least make the signal path plugs and power ones a different size, that makes it a bit harder to plug yourself into the mains. I also count about 30 connections, points of failure, between input jack ground connection and mains earth, that can't be clever.

Since the circuit is in plastic boxes there is no requirement for mains earth, except for the power transformer core which is metal of course. If Gerry put the IEC socket, transformer and earth all in the same box it would at least put the project in the grey area rather than in the immediately illegal area.

A further modification would be to have each jack lead permanently wired to its downstream box (and use those safety jack plugs/sockets). That way you at least can't get a direct connection to B+ when a lead is unplugged.

[Gerry Rzeppa]

I would at least make the signal path plugs and power ones a different size, that makes it a bit harder to plug yourself into the mains. I also count about 30 connections, points of failure, between input jack ground connection and mains earth, that can't be clever.

Did you take length into consideration when designing this amp? And/or portability?
I understand the buyer/builder would have to provide their own chassis but how long does the signal chain measure? Seriously?
I feel like some design elements have been overlooked in favour of banana plugs. They aren't that good.

It's an educational product, guys. A hands-on no-solder way of explaining how a tube amp works -- the various subsystems and how they fit together. (Sing along! "Oh, the input's connected to the preamp, and the preamp's connected...").

And, with a handful of optional modules, it lets the student easily try different configurations to see (and hear) what happens (in accord with clear instructions, of course). What, for example, are hi- and lo-gain inputs? How do they work? What happens when we put the volume control before (instead of after) the first amplifier unit? How does a single-knob tone control differ from a Marshall-style tone stack? from a Fender-style? How much loss do we suffer from a tone control/stack? What happens when we put an additional amplifier unit after the tone control/stack? before the tone control/stack? What's the difference between a "gain" and a "volume" control? Where do they go in the circuit? What do they really do? How does an EL84 power amp differ from a 6V6? How does each sound? Does a solid-state rectifier sound different than a vacuum tube rectifier? What effect does additional (or less) power supply filtering have on hum levels?

The kind of stuff that's very hard to do without banana jacks.

[mac]

A good and certified Fender or Marshall can kill, even when components are soldered, as usual.
A banana amp is not, and can kill too.
I wrote as usual in red because a lawyer will have little trouble trying to convince a jury that is custumary in this industry to solder components. And it is very likely that most jurors know what a solder is, or have seen a soldered pcb.
Just a thought

mac

[samhay]

Gerry - how long do the power caps stay charged after you turn it off?
If you are using it as a demonstration tool, it might be nice to have some way to bleed these caps, so that one can quickly switch the modules around without having to worry about grounding them through someone.

[Gerry Rzeppa]

...a lawyer will have little trouble trying to convince a jury...

"The first thing we do, let's kill all the lawyers.'' -- Henry VI, Part II, act IV, Scene II.

[Gerry Rzeppa]

Gerry - how long do the power caps stay charged after you turn it off?
If you are using it as a demonstration tool, it might be nice to have some way to bleed these caps...

There's a bleeder resistor in the rectifier/filter module. Down to 5 volts in less than 3 seconds.

[R.G.]

It's an educational product, guys. A hands-on no-solder way of explaining how a tube amp works -- the various subsystems and how they fit together.

Oh. Kewl! OK, then, it's only for educational purposes - and thereby specifically intended for people who almost by definition don't know how the things work or what the dangers might be. 

I missed the section in the Kickstarter that said that "this is for educational and/or experimentation uses only, and not for long term use outside a supervised environment." Can you give me a link to that section?   

I do notice that we've convinced you that you need to at least disclaim use without a cabinet, and make that explicit. That's new, like the "is it safe" FAQ was new after the discussions here.   

Although "cabinet before taking his amp "on the road"" does at least implicitly imply that it is durable enough to take on the road.

And [#5] it's not us you have to convince.   

[Gerry Rzeppa]

...it's only for educational purposes - and thereby specifically intended for people who almost by definition don't know how the things work or what the dangers might be.

It's primarily for educational purposes. Somebody's first tube amp kit. Something that will give him or her enough confidence and courage to take up soldering, and later build more difficult (and less safe) amp kits.

I missed the section in the Kickstarter that said that "this is for educational and/or experimentation uses only, and not for long term use outside a supervised environment." Can you give me a link to that section?

Kickstarter is for products in seminal (or concept) form -- products that will undoubtedly develop in different directions depending on feedback from the backers, funding, market demand, etc. The Banana Jack Amp in the video is clearly labeled as a prototype. The one on my bench is already a different and improved model. Hence, the Kickstarter description is intentionally generic and open-ended, suggesting various routes for further development of the basic concept.

I do notice that we've convinced you that you need to at least disclaim use without a cabinet, and make that explicit.

If somebody is using our modules in an educational environment, the modules will probably not be installed in a cabinet; if somebody has constructed an amp for use on the road, our modues will probably be installed, securely, inside a cabinet. It's up to the user. We're marketing components, not finished products -- like the guys who sold me the tube sockets and transformers and power-cord connectors in the first place; our components are just at a little higher (and more convenient) level. Note that this greater convenience does not change their nature as components; it just makes them easier to assemble: as push-in connectors on the back of a wall socket (in addition to screw terminals) makes them easier to install, but doesn't change their nature as electrical components.

That's new, like the "is it safe" FAQ was new after the discussions here.

As I mentioned above, it's expected that a Kickstarter prototype -- and the description thereof, especially the FAQs -- will develop over time. When I first posted the project, I didn't have any frequently asked questions -- in fact, I didn't have any questions from backers at all! I've been adding to the FAQ on the Kickstarter site as people write directly to me there.

Although "cabinet before taking his amp "on the road"" does at least implicitly imply that it is durable enough to take on the road.

"On the road" means different things to KISS and the kid down the street. I can easily envisage an amp suitable for lugging to local gigs made out of our modules securely fastened and enclosed inside a typical tolex-covered cabinet.

And [#5] it's not us you have to convince.

Exactly whom do I have to convince? The backers on Kickstarter? They're already on board. Perhaps the folks at Tube Depot who sell those "scary" S5 kits (http://www.s5electronics.com/thome.html) and who have expressed an interest in selling ours as well? I don't see them having a problem with our design. Whom?

[R.G.]

 

It's primarily for educational purposes. Somebody's first tube amp kit. Something that will give him or her enough confidence and courage to take up soldering, and later build more difficult (and less safe) amp kits.

Well, it's tempting to say that learning which end of the soldering iron to hold onto would be valuable experience for someone who intends to go messing about with things which are dangerous to touch, but I won't go there.

So which part of the description says it's primarily for educational purposes?

Kickstarter is for products in seminal (or concept) form -- products that will undoubtedly develop in different directions depending on feedback from the backers, funding, market demand, etc. The Banana Jack Amp in the video is clearly labeled as a prototype. The one on my bench is already a different and improved model. Hence, the Kickstarter description is intentionally generic and open-ended, suggesting various routes for further development of the basic concept.

The bureaucratic version of that tends to be "when in doubt, mumble", but I won't go there either. So is the Kickstarter funding for building a prototype? Don't you already have one of those?  Or will the kickstarter funded prototype be better, faster, whatever? Will it be anything like the one on the bench?

If somebody is using our modules in an educational environment, the modules will probably not be installed in a cabinet; if somebody has constructed an amp for use on the road, our modues will probably be installed, securely, inside a cabinet. It's up to the user. We're marketing components, not finished products -- like the guys who sold me the tube sockets and transformers and power-cord connectors in the first place; our components are just at a little higher (and more convenient) level. Note that this greater convenience does not change their nature as components; it just makes them easier to assemble: as push-in connectors on the back of a wall socket (in addition to screw terminals) makes them easier to install, but doesn't change their nature as electrical components.

OK, I get you. Like Tom Lehrer's song "Werner Von Braun", "... der rrrrockets go up, who cares vere dey come down? Dat's not my department - says Verner Fon Braun".

As I mentioned above, it's expected that a Kickstarter prototype -- and the description thereof, especially the FAQs -- will develop over time. When I first posted the project, I didn't have any frequently asked questions -- in fact, I didn't have any questions from backers at all! I've been adding to the FAQ on the Kickstarter site as people write directly to me there.

Kewl. So how many people wrote directly to you there to ask if it was safe, and what were their questions?

"On the road" means different things to KISS and the kid down the street. I can easily envisage an amp suitable for lugging to local gigs made out of our modules securely fastened and enclosed inside a typical tolex-covered cabinet.

Yep. I can easily envisage a neutron bomb being suitable for transport encased in a steel and lead sarcophagus welded to a railroad car and escorted by a convoy of tanks, Army Rangers and overhead air support. "On the road" means different things to different people, I guess.

So for local gigs a typical tolex covered cabinet is OK. Good. At what distance do you exceed "local"? 20 miles? 30 minutes in a car? 30 minutes in a plane?

Exactly whom do I have to convince? The backers on Kickstarter? They're already on board. Perhaps the folks at Tube Depot who sell those "scary" S5 kits (http://www.s5electronics.com/thome.html) and who have expressed an interest in selling ours as well? I don't see them having a problem with our design. Whom?

The first person who gets shocked by the wires or burned by the open air tubes, or their parents or guardians, lawyers, judge, jury, and/or heirs. That would be a great start.

Just sayin'.

But whomever that is, it's [#6] not us you have to convince.

[Gerry Rzeppa]

So which part of the description says it's primarily for educational purposes?

Pretty much the whole illustrated center section of the blurb: "If you've read this far, you're bright enough to learn how it all works. Kenn Amdahl's delightful book, "There Are No Electrons: Electronics for Earthlings", is included with every kit [illustration of educational book]. Combine that with our step-by-step instructions and life-size schematic diagrams that explain traditional nerd-squiggles in the same simple terms that Kenn uses [illustration of schematic]... and add to that our crystal clear modules that you can take apart WITHOUT TOOLS so you can see all of the wee bits and pieces [photo of exposed components inside a module]... and you've got an educational package that can't be beat."

So is the Kickstarter funding for building a prototype? Don't you already have one of those?  Or will the kickstarter funded prototype be better, faster, whatever? Will it be anything like the one on the bench?

The Kickstarter funding is for the further development of a prototype into a commercially viable product. In our case, the final version will most likely include optional modules (tone controls, different kinds of rectifiers, etc), and may also include standard and/or optional speakers, enclosures, etc. It all depends, again, on what the backers have to say, the amount of funding that is realized, indications of market demand, etc.

OK, I get you. Like Tom Lehrer's song "Werner Von Braun", "... der rrrrockets go up, who cares vere dey come down? Dat's not my department - says Verner Fon Braun".

Not quite that cavalier. The packaging and instructions will be chock-full of warnings, cautions, and other admonitions encouraging safe use.

So how many people wrote directly to you there to ask if it was safe, and what were their questions?

Two so far. The first asked, "Is it safe to run hundreds of volts from the transformers down a banana jack? Even barring component failure, what about user error? Isn't there strict electrical compliance issues for safety that might not even allow something like this to be sold?" The second was more statement than question, and too lengthy to repeat here: suffice it to say it was essentially a not-too-concise summary of the objections raised on this forum.

Yep. I can easily envisage a neutron bomb being suitable for transport encased in a steel and lead sarcophagus welded to a railroad car and escorted by a convoy of tanks, Army Rangers and overhead air support. "On the road" means different things to different people, I guess.

C'mon, now. I'm sure you can picture our modules securely screwed down inside a typical "tolex" speaker box with some kind of cutouts exposing the input jack, the volume control, and the face of the power module -- without exposing any of the banana jacks or cables. And I'm sure you can imagine such a configuration being reasonably reliable over a long period of time.

So for local gigs a typical tolex covered cabinet is OK. Good. At what distance do you exceed "local"? 20 miles? 30 minutes in a car? 30 minutes in a plane?

I'm not sure it's distance that matters; it's more the kind of abuse the amp gets on the way.

The first person who gets shocked by the wires or burned by the open air tubes, or their parents or guardians, lawyers, judge, jury, and/or heirs. That would be a great start.

Hopefully, no one will fall into that category. But since such concerns don't stop other amp-kit manufacturers, I don't see why they should deter us.

But whomever that is, it's [#6] not us you have to convince.

I'm not sure why you keep saying that. Is it simply that you'd like the last word?

[vigilante397]

Just read this entire thread. Commenting so it's easier to follow along as it progresses

[PRR]

> follow along as it progresses

[tubegeek]

Prediction: this thread will not progress.