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

[Gerry Rzeppa]

Now on Kickstarter, looking for backers:

https://www.kickstarter.com/projects/1335354839/banana-jack-amps-no-solder-all-tube-guitar-amp-kit

Check it out. Tell your friends. Thanks!

 

[Gerry Rzeppa]

UPDATE UPDATE UPDATE

We've added the "Coppertone" option. See the Project Update:

https://www.kickstarter.com/project...-amps-no-solder-all-tube-guitar-amp-kit/posts

 

[JMFahey]

Banana Jack Amps: a KILLER Amp ... literally
For those who are tired of life and might want to end it with a flash, search no more, https://www.kickstarter.com/projects...guitar-amp-kit are here to stay.

A seemingly nice and original idea when drawn on a paper napkin, HORRIBLY put in practice by Mr Gerry Rzeppa .
https://www.kickstarter.com/projects...get/video.html

The idea is that you have 9 pre built (soldered, of course) modules and you interconnect them to build and mod amps "without soldering".
LEGO style of course.

Problems:

1) banana jacks are used for interconnection (duh !!!)

An externally hosted image should be here but it was not working when we last tested it.

as it's easy to see, all have a thick 3/4" exposed ... er .... "banana" on the end, which of course is metallic and is used to carry voltage and current.

We all know the kind of voltages which are used in TUBE amps

2) as shown, this amp has input on left, power to the right, with mains to the extreme right, and sequence follows classic Tube Amp signal path .

Now IF you connect left to right, the exposed tip banana you are holding in your bare hand, carries no voltage, because voltage comes from the right.

BUT if you plug any right hand banana, and hold the left in your hand while reading the leaflet or whatever, you WILL have voltage.

How much voltage?

Well, the rightmost box is directly connected to mains, so those grey banana jacks carry live and neutral 120V (240V in Europe). (0:34 in the Video).
Which you can grab when fiddling with the banana.

They go to the Power transformer.

Now it starts getting better:

The PT boosts to 300+300VAC , and dutifully sends them to the rectifier tube ... through another pair of bananas, again grey but now sporting some 600VAC end to end.

Just what I needed for my homemade

An externally hosted image should be here but it was not working when we last tested it.

I think you already got the idea.

The rectifier supplies more than 300VDC to the Output Transformer, the preamp tubes get their share (think 250V DC) , always through nice exposed end bananas.

3) By the way , even if using shrouded bananas (which he already said he won't, because they cost almost 6$ each instead of less than a buck apiece) , the flimsy plastic boxes can be opened without tools (sic).

4) don't forget to check the actual SOUND of this execution device:

https://d3mlfyygrfdi2i.cloudfront.ne...2Fkickskin.swf

 

[Gerry Rzeppa]

The idea is that you have 9 pre built (soldered, of course) modules and you interconnect them to build and mod amps "without soldering".

Correct as far as it goes. The design goals were three:

(1) Produce an educational kit, that
(2) Results in something interesting and useful and that is more than a toy, and that
(3) Is built entirely with "basic" or "fundamental" electronic components (like resistors and transformers rather than op-amps and microprocessors).

Problems: 1) banana jacks are used for interconnection.

I think that should be listed under "Features" rather than "Problems".

We all know the kind of voltages which are used in TUBE amps

That's why our instructions include cautionary warnings, in bold, colored, eye-catching text, on every page.

And of course our voltages are no different than any other small valve amp kit. For example, in assembling these popular kits (Untitled , MOD 102 Guitar Amp Kit | MOD Kits DIY) the student manually cuts and strips high voltage transformer wires and solders them to the rectifier circuitry with a hot iron; with our kit, the student connects the transformer module to the rectifier module with a few color-coded banana cables. In both cases, perfectly safe operations if the thing is not plugged in; in both cases, dangerous if the thing is plugged in.

...Now IF you connect left to right, the exposed tip banana you are holding in your bare hand, carries no voltage, because voltage comes from the right. BUT if you plug any right hand banana, and hold the left in your hand while reading the leaflet or whatever, you WILL have voltage.

Only if you're fool enough to plug the thing into the wall and turn it on -- contrary to the warnings on every page of the instructions -- before you build the thing! And again, the same dangers are present in every other tube amp kit.

How much voltage? ...120V ... 300+300VAC ... 600VAC

Actually, the highest voltages carried on a single cable in the current prototype are 120 vac and 240 vdc.

By the way, even if using shrouded bananas (which he already said he won't, because they cost almost 6$ each instead of less than a buck apiece)

It's true that we've had trouble finding an affordable source for shrouded banana plugs and jacks. But we haven't stopped looking. And we're now offering "cabinet, panel, and speaker kits" to compliment our modules and to support more permanent installations where the cables, once connected, would be out of reach inside the cabinet. See the photos below for what they'll look like.

the flimsy plastic boxes can be opened without tools.

I wouldn't call our plastic cases "flimsy"; they are precision manufactured and 1/8-inch thick. And the fact that they open, easily, is a feature -- especially in an educational product -- not a "problem". We want the student to have access to the basic components so he can study them. And for the third time, I don't see how this differs from other amp kits where the student can poke around in the open chassis any time he pleases.

Note that we hope to offer a variety of modules in addition to the nine Mr. Fahey mentions: various tone stacks, gain controls, alternate power amps; and voltmeter and ammeter and perhaps even 'scope modules as well.

Here are a couple of pictures of our prototype Coppertone amp kit, to give you an idea of how our modules (mounted to the back of the copper panels) might be enclosed:

This is the "totally enclosed" option we're not offering on our Kickstarter Project Update.

 

[Gerry Rzeppa]

Apples to Apples

Okay folks, let's see if we can put this "safety issue" to rest by comparing apples to apples. Here we have:

Top Left: An assembled Banana Jack chassis, ready for testing, further mods, etc.

Top Right: An assembled Mojotone Bassman chassis, ready for testing, further mods, etc.

Bottom Left: A Banana Jack chassis installed in a user-designed cabinet.

Bottom Right: A Mojotone Bassman chassis, installed in a user-designed cabinet.

An externally hosted image should be here but it was not working when we last tested it.

I really don't see why anyone would think the stuff on the left is more dangerous than the stuff on the right. Seems to me, at the chassis level, the Banana Jack kit is much safer than the Mojotone Bassman. And once they're each fully enclosed, well, they're fully enclosed.

 

[JMFahey]

Bottom Left: A Banana Jack chassis installed in a user-designed cabinet.

An externally hosted image should be here but it was not working when we last tested it.

That one is not a Banana Jack Amp by any means but a Coppertone Amp, which uses conventional metallic chassis and is enclosed in wooden cabinets.

FWIW the Coppertone looks safe enough, while the Banana Jack Amp is visibly dangerous.

FWIW UL , CSA , IEC, TÜV, SEMKO, and all other Electrical Safety Agencies in the World do not allow exposed metal parts carrying dangerous voltages nor parts which can be opened without tools allowing access to such voltages.

That's why, for example, panel fuse holders with bayonet or screw caps which can be opened without tools (just with the bare fingers) are not allowed any more on new equipment.

Modern ones require at least a screwdriver tip to be opened.

And now there's a trend to either not have externally accessible fuses or at least mount them in a small plastic tray so it extracts them for replacement ... but previously disconnects them from both fuse clips.

An externally hosted image should be here but it was not working when we last tested it.

While your bananas can be pulled any time from a powered amplifier exposing high voltages.

It's not enough writing a ton of warnings, Electrical Safety Agencies won't rely on that, it must be physically impossible to access parts with dangerous voltage without disassembly, pulling screws,etc.

Those Tube amps chassis you (wrongly) show as examples of stuff "as dangerous as yours" are not right: they live permanently inside a cabinet, and are only pulled from them but Techs, in a Servicing environment.

The usual amp labels clearly say "Danger of shock" "Refer Servicing to qualified personnel" ... plus the danger is permanently enclosed.

You supply no labels, the warnings are in the manual (something People is often known not to read) and anyway pulling a banana is kid's play .

I repeat:
In your amp, death is only one banana jack pull away ... which is very easy to do even for a small kid.

 

[Gerry Rzeppa]

An externally hosted image should be here but it was not working when we last tested it.

That one is not a Banana Jack Amp by any means but a Coppertone Amp, which uses conventional metallic chassis and is enclosed in wooden cabinets.

I beg to differ. That's a virtual prototype of a Banana Jack Amp in a Coppertone-style cabinet. Here, for example, you can see the clear plastic Banana Jack volume control module (with an appropriate knob) attached to the back of the copper panel:

An externally hosted image should be here but it was not working when we last tested it.

And that's only one way you can use our Banana Jack modules to construct a fully-enclosed tube amp of your own design -- without soldering!

With Banana Jack Amp Modules, you can quickly figure out what you want on your bench (using the same caution you would with any other amp kit), and then install your circuit in the cabinet of your dreams. All without soldering! and de-soldering! and re-soldering!

Good stuff.