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

[slacker775]

I've actually read this entire thread and do not see anyone trying to kill this project.   I see people giving informed suggestions to actually protect you and yet you are completely misinterpreting everything they say.   Helpful - albeit perhaps not what you want to hear - information from folks that bear the scars should always be considered and integrated in your thinking.

[duck_arse]

lost me at god.

whose god?

[J0K3RX]

I would reconsider using the banana jacks for obvious reasons... Maybe consider something along the lines of what AMT has done? Perhaps use a different kind of male and female plugs, but I do like the new found use for the DB9!















 

[vigilante397]

Is there anything like an XLR plug that could be useful in this situation? Not necessarily an XLR plug, but I think something that has to go into a predefined hole (you could even use different plugs in different instances to make sure the wrong cable isn't in the wrong plug), will not rotate after it has been properly inserted, and will LOCK into place, requiring legitimate effort and fine motor skills (decreases the accidental unplugging and very small child risk) to unplug. Something like a speakon would work great as well. Obviously you couldn't call it the banana amp anymore, but I'm just trying to help, as is everyone else here. I think this idea has great potential, and I don't want you to give up on it and I hope you don't, but I hope you do realize there is room for improvement.

vigilante397 - not part of the problem, part of the solution, since 2014

[J0K3RX]

Is there anything like an XLR plug that could be useful in this situation? Not necessarily an XLR plug, but I think something that has to go into a predefined hole (you could even use different plugs in different instances to make sure the wrong cable isn't in the wrong plug), will not rotate after it has been properly inserted, and will LOCK into place, requiring legitimate effort and fine motor skills (decreases the accidental unplugging and very small child risk) to unplug. Something like a speakon would work great as well. Obviously you couldn't call it the banana amp anymore, but I'm just trying to help, as is everyone else here. I think this idea has great potential, and I don't want you to give up on it and I hope you don't, but I hope you do realize there is room for improvement.

vigilante397 - not part of the problem, part of the solution, since 2014

Nathan/vigilante397 - great ideas!! But, what if a toddler, small child just so happened to "all of a sudden" get the irresistible urge to partake of a power tube or a preamp tube (I know I would!) and let's say for example he or she tries to suck on a hot 12AX7 or 6L6?  Now we have possible shock, burned lips, broken glass, mental scars and a dirty diaper!! And, I know how I just love to drag my tongue across a nicely wound HV transformer, and don't even get me started with caps!!  

[Gerry Rzeppa]

I think this idea has great potential, and I don't want you to give up on it and I hope you don't, but I hope you do realize there is room for improvement.

Thanks.

Is there anything like an XLR plug that could be useful in this situation? Not necessarily an XLR plug, but I think something that has to go into a predefined hole

Haven't been able to find anything like that that is (a) readily available, and (b) reasonably priced.

(you could even use different plugs in different instances to make sure the wrong cable isn't in the wrong plug),

Using different types of connectors for different purposes would increase the cost, since each type of connector would have to be purchased in smaller quantities, etc. And the finished product would probabaly be less aesthetically attractive. We think color-coding is sufficient keep our intended audience from making mistakes.

will not rotate after it has been properly inserted,

I don't see why this is important.

...and will LOCK into place, requiring legitimate effort and fine motor skills (decreases the accidental unplugging...

I wish you guys had some actual experience with one of our amps. The plugs and jacks we use are really quite "tight" (they're not like the ones on a typical voltmeter). Significant effort is required both to insert and remove them; I can't imagine them getting accidentally unplugged.

... and very small child risk) to unplug.

"Very small child risk" is not a consideration in the design of this product; we're not putting these in McDonald's Happy Meals.

Something like a speakon would work great as well. Obviously you couldn't call it the banana amp anymore,

And here we meet with the "tension between competing objectives" that every designer must resolve. Connector size, color, look, feel; cost; marketing considerations; and many more. Using "speakons" would require much larger modules, would cost a great deal more, and would obsolete all of our marketing to date (company name, theme song, product recognition, etc). We thought of all the things that have been suggested here, believe it or not, in the design process that preceded release of the prototype on Kickstarter; and we thought (and still think) our design represents a very elegant balance between the various competing objectives.

Note the Project Update on our Kickstarter page. When we change the relative importance of various objectives we can offer a different product that is more suitable for actual use in a band, easier to transport, and that has all the connectors and cables fully enclosed. But note that we lose some important educational features (like ease of modification) and important market consderations (like a significant price increase).

but I'm just trying to help, as is everyone else here.

And your honest efforts (and the honest efforts of others here) are appreciated. All input is good input. The difficulty here is in getting people to see that product design is -- as I've said -- the art of balancing competing objectives. It's easy to pick out one thing -- like "safety" -- and harp on that to the exclusion of all the other project objectives. A poster here can go on and on about perceived safety considerations without ever thinking about cost, aesthetics, educational value, marketing, etc. I can't do that; I have to design a product that takes into account all of the project's competing objectives, and actually build and deliver that product to the backers on a very tight budget. So I try to create something that is reasonably priced, reasonably safe, reasonably good looking, reasonably easy to understand, use, modify, etc. And I think I've done that. Taking into account our project update, I'd say I've done it twice.

[Gerry Rzeppa]

...what if a toddler, small child just so happened to "all of a sudden" get the irresistible urge to partake of a power tube or a preamp tube (I know I would!) and let's say for example he or she tries to suck on a hot 12AX7 or 6L6?  Now we have possible shock, burned lips, broken glass, mental scars and a dirty diaper!! And, I know how I just love to drag my tongue across a nicely wound HV transformer, and don't even get me started with caps!!  

I hope you're being facetious. When we say a product is "safe" we mean "reasonably safe for the intended user". Happy Meals are safe for kids; chain saws are safe for lumberjacks. Since our amp kits are not intended for "toddlers", we -- like the manufacturer of chain saws -- don't have to worry about how our product might affect them if an irresponsible adult happens to put one within reach.

[Gerry Rzeppa]

lost me at god. whose god?

Wrong forum for that discussion. Try here: http://pleiotropy.fieldofscience.com/2009/04/rzeppa-game-show.html

[Ice-9]

This whole topic is just going around in circles and I imagine the more posts irrelevant or not will help with the search engines and kickstarter hits going but will not make anyone listen to each other.

Personally I would fail this as an idea now, but look into the copper amp idea, not as a kit build but as a ready built high quality amp.

[pickdropper]

This whole topic is just going around in circles and I imagine the more posts irrelevant or not will help with the search engines and kickstarter hits going but will not make anyone listen to each other.

I agree.  Some of us gave some opinions and advice based our previous experiences.  Obviously, Gerry feels confident in his direction and isn't looking for external feedback.  I see no indication of that pattern changing.  It might be best just to let the thread fade out.

[Ice-9]

I wonder why half of each 12ax tube is being wasted in each the modules ?

[Gerry Rzeppa]

Personally I would fail this as an idea now, but look into the copper amp idea, not as a kit build but as a ready built high quality amp.

Yes, that would probably succeed. But I really don't want to be a "boutique" amp builder. No educational value. I'm a teacher at heart. And I like stuff that's bargain-priced.

Curious aside: When I posted about my "boutique" Coppertone amps over at The Amp Garage, response was remarkably positive. See, for example:

http://ampgarage.com/forum/viewtopic.php?t=24998

http://ampgarage.com/forum/viewtopic.php?t=25393

But when I started talking about bringing tube amp building to the masses, by simplifying, removing stumbling blocks, following electron flow (rather than conventional current), etc, well, you can see what happened here:

http://ampgarage.com/forum/viewtopic.php?t=25541&highlight=enough+gerry

(The offending thread has unfortunately been removed so first-hand data is unavailable.)

[Gerry Rzeppa]

I wonder why half of each 12ax tube is being wasted in each the modules ?

The prototype in the Kickstarter video has six modules in the signal path:

input > preamp (12AX7) > volume > intermediate amp (12AX7) > power amp (6V6) > output transformer

Only one-half of each 12AX7 is used for educational purposes -- so the physical signal flow is strictly left-to-right through the modules (with no wires "doubling back"), and so the physical modules match the "life size" schematic that comes with the kit. This arrangement also provides for easy experimentation; for example, the leftmost modules can be configured in any of these ways (since the two 12AX7 modules are essentially identical):

input > preamp > volume > intermediate >
input > volume > preamp > intermediate >
input > preamp > intermediate > volume >

And with an additional volume module, like this:

input > volume > preamp > volume (gain) > intermediate >
input > preamp > volume > intermediate > volume (gain) >

Etc. The current prototype (on my bench) includes a tone control that can be inserted in various places in the circuit:

input > preamp > volume > tone > intermediate >
input > preamp > volume > intermediate > tone >

And so forth. In this newer prototype, the 12AX7 module has both sides of the tube connected in parallel for greater gain and less noise, while still maintaining "schematic simplicity" -- we treat it as a "super 12AX7" and postpone discussion of the details of the physical implementation until later in the course when the student has become comfortable with a typical cathode-biased triode amp circuit. We're thinking of offering a 12AX7 module with the halves connected in series, as well.

[Seljer]

Only one-half of each 12AX7 is used for educational purposes -- so the physical signal flow is strictly left-to-right through the modules (with no wires "doubling back")

Which means you could easily use some kind of combination of female/male jacks so the section in the direction of the power supply only ever had an exposed female jack and no exposed high voltage metal parts!

[Gerry Rzeppa]

Some of us gave some opinions and advice based our previous experiences.  Obviously, Gerry feels confident in his direction and isn't looking for external feedback.

I think you're selling yourself short. It was input from forums like this that inspired me to update the Kickstarter to include the fully-enclosed Coppertone alternative (which completely eliminates the perceived "exposed high voltage wire" problem). So the project now has two potential directions, rather than just the original one. And the backers can cast their votes for whichever they prefer by choosing the one or the other as a reward: (a) low-level, inexpensive, educational kit? or (b) high-level, more expensive, "finished product" kit?

[Gerry Rzeppa]

Which means you could easily use some kind of combination of female/male jacks so the section in the direction of the power supply only ever had an exposed female jack...

We could if there was such a thing (a) readily available in small quantities, (b) at a reasonable price, (c) in the necessary colors, (d) in an comparable size, and that (e) is solderless at the cable end (so the student can make longer and short cables to complement his own designs without soldering). Not to mention (f) single conductor, and (g) able to handle 240 volts, etc.

If you know of such a thing, please post a link and I'll give it serious consideration. The closest I've found to date is "shrouded" or "sheathed" banana plugs, which unfortunately fail on points (b), (c), and (e) above.

...no exposed high voltage metal parts!

There are no exposed high voltage metal parts in a properly assembled kit. Nor are there exposed high voltage metal parts during assembly and modification, if just one simple (and obvious) instruction is followed -- don't plug the thing in the wall unless all cables are fully inserted into the proper jacks.

[Thecomedian]

"Each day, nearly 7 children are treated in hospital emergency rooms for electrical shock or burn injuries caused by tampering with a wall outlet."

I think you may be misquoting that: "...injuries caused by tampering with a wall outlet" should read "...injuries caused by their parents not paying enough attention." What kind of people let their kids tamper with wall outlets?

But even so: 7 out of 300,000,000 is a miniscule percentage (I'm assuming we're talking the U.S. only here, the report wasn't clear). 39 times that number, according to the report, are injured by hot tap water! (We keep our water hot enough to make a cup of tea, right out of the tap; no member of my extended family has ever been injured by this means. Again, it's not the wall sockets or the hot water that's the problem: it's the parents.)

In any case, I think it's fair to call something (like a standard wall socket) that fails to injure 299,999,993 people out of 300 million reasonably safe.

<=7 per day. Almost 2.5k per year. Would you want to have a fried child on your conscience by not looking into making it as safe as possible? I think that's all anyone is saying. Color coding isn't really idiot proof like different shape jacks. I'm certain it's not easy to design a modular learning system, but most learning systems err for safety first.

Every guitar-picker knows that tube amps sound the best. And everyone knows that an amp that you build with your own hands is, well, something that's uniquely yours.

But tube amp kits cost a lot, they're hard to put together, and nobody but nerds can understand them. Which is why we're making Banana Jack Amps: all-tube, vintage-tone, easy-on-the-wallet, simple-to-assemble, crystal-clear guitar amp kits that can be put together WITHOUT SOLDERING.

I know you're going to put HV warnings in there, but the language will appeal to lowest common denominators for lack of foresight, laziness, and possibly intelligence. It may be Darwinian, but there is still some social responsibility.

It is an appealing product as it stands for someone who knows how to be careful and is a bit older in life. I hope it does work out in the future.

[Seljer]

http://uk.farnell.com/wago/2092-1306/terminal-block-pcb-6-way-5mm/dp/2352344
http://uk.farnell.com/wago/2092-1406/terminal-block-pcb-6-way-5mm/dp/2352355

Theres bazillions of connectors out there, probably something similar and right-angled too.

[Gerry Rzeppa]

<=7 per day. Almost 2.5k per year.

2.5k out of 300m is still a miniscule percentage. Which indicates a reasonably safe product (the wall socket). A kid, for example, has a much better chance of getting hit by lightning (1 in a million, on average) than getting hurt by a Banana Jack Amp (essentially zero percent, since we've only got 2.5k/300m getting hurt via wall sockets and there are billions of those within easy reach of a child, but -- even if we get fully funded -- only about 100 Banana Jack Amps, and all of those (assuming reasonably responsible customers) out of the reach of children).

Would you want to have a fried child on your conscience by not looking into making it as safe as possible?

Of course not. But I think I have made it reasonably safe for the intended audience, and it's their responsibility -- not mine -- to keep it away from small children.

I think that's all anyone is saying.

It seems to me people are saying, "Make this thing completely 'idiot proof' -- safe enough to give away in a Happy Meal." Which would be nice, but -- due to the nature of the beast -- can't be done. There's no such thing as a child-proof chain saw; nor is there such a thing as a child-proof tube amp. What, for example, stops a child from sucking on the female end of a standard IEC power cord while the male end is plugged in the wall and getting enough saliva in there to get a shock? How do we "fix" that?

Color coding isn't really idiot proof like different shape jacks.

True. But I'm not trying to make an 'idiot proof' amp kit; I'm making an affordable amp kit for reasonably intelligent students; students bright and disciplined enough to read and understand Kenn Amdahl's 217-page book, included in every kit.

I know you're going to put HV warnings in there, but the language will appeal to lowest common denominators for lack of foresight, laziness, and possibly intelligence. It may be Darwinian, but there is still some social responsibility.

Sure. And the accepted standard is: "reasonably safe for the target market -- with clear warning to others."

[Gerry Rzeppa]

It is an appealing product as it stands for someone who knows how to be careful and is a bit older in life. I hope it does work out in the future.

Thanks.