Amp prototyping

[a_e_a]

Hey Guys,

I just recently finished my first build and I have the bug. Now I am looking at not only building another but building something I can learn from.

My idea is to build something similar to a beavis board http://www.beavisaudio.com/bboard/
for amp design rather than pedals.

I was thinking a hard wired el84 or 6v6 single ended output with a breadboard to try different preamps and basically not have to solder/desolder everytime I want to try different values and see how they affect tone etc.

Has anyone done this? What do you guys use when prototyping amps? Thanks for the help guys!

[tubeswell]

A hunk of wood with some brass/copper screws in it for soldering parts onto. Or if you want to get more refined, a hunk of wood with some terminal/tag strips screwed onto it. There you go. (Been done before many-a-time I might add). But don't expect superior shielding.

[overtone]

Tubeswell is right, especially with a single ended output section you will have to learn to listen past the buzz and noise. But I find being able to quickly prototyping your own ideas is well worth it.

I use two rows of terminal blocks on a timber board about two and a half feet long to test ideas and layouts before committing myself. That board sits in another base-board which can safely take the bolted down transformers to the rear side. I also have about ten or so aluminium boards pre-wired with octal and noval sockets terminating at terminal blocks. There are various strips or places where I can write notes on, like B+2, or G-2 etc. for each connection. That is really useful because it can get to look like a mess.
If you use terminal blocks or a breadboard with a similar spacing to what you will eventually use (tag strips / turrets / eyelets, pcb etc.) you can get good feedback on the space requirements of your layout.
This is a really basic set up for quick tests. I have seen guys using HV breadboards for longer tests, but that is a much larger financial investment.

[jmohr58]

Using the methods of HV breadboards or putting it on wood with correctly spaced terminals would be okay, but please do not consider using the type of breadboards which are in this Bevis Audio kit. That would be an electrocution waiting to happen with the voltage/amperage levels that exist in tube amp circuitry.
I used those same breadboards learning digital and low voltage analog circuits and for that they are okay, but a death trap for high voltage.
Tubewell and overtones ideas are much safer.
In additon, those smaller breadboards do introduce stray capactitance into your circuitry that can effect what you are building even on a low voltage level. It was not a problem using TL and CMOS IC chips but building analog it was always something to keep in the back of your mind.
The idea is a good one but design something on a large flat block/board of wood with screw down tag strips attached or small metal studs with wood threads on one end to mount into the wood and metal thread on the other end to attach wires to with washers and nuts. You could get a multi screw Ground bus bar out of a fuse box for a ground point to mount on the wood from THD or Lowes possibly.
Just be careful and respectful of the High Voltage levels as I am sure you are already aware of since you have already built an amp.

[markr14850]

There are some ideas here: http://www.tubelab.com/The_Tubelab.htm

[jmohr58]

Great link,
Really good idea.
I am sure several guys will find this a good approach.
Thanks, I may be off to the hardware store today!

[markr14850]

Be sure to shop around for the pegboard. Some online places charge obscene amounts - like $60 for one panel.

Here you can find a 2' x 4' section for $17.79: http://www.doitbest.com/Pegboard+and+pe ... 112976.dib

BTW, let me know if you find a way to cut it that isn't a complete mess.

--Mark

[surfsup]

Daaaaammmnnnnnn!

[img:657:532]http://www.tubelab.com/images/TL3/Tubelab3.jpg[/img]

[overtone]

A lot of knobs in that photo.

Those are very good points made by jmohr58 above.

One thing that I would like to say about the European style terminal blocks, as shown in the picture above, is that it is easy to make a bad connection. Often I find them to be the cause of electrical faults in buildings. You need to make sure that the leads or cables really are being gripped and held in place by the screw. When the lead or wire is small, which will most likely always be the case for us, they can slip alongside the screw, and not be held in place. The high end ones have a shoe under the screw to prevent this.

I forget the British name for what I am calling a terminal block, but it is Lusterklemme, Blockklemme oder Reihenklemme in Germany. Some of them on the market are just junk but most Hardware stores here have the 700V rated ones. Barrier strips are more heavy duty. I have some nice ones in ceramic, but I usually just use a similar type to those shown in the photo.

[Structo]

I always thought these things were cool.

These are a bit expensive but you could certainly make up some boards like this yourself and make a modular prototype system that you join together in different stages.

[img:500:165]http://www.tubesandmore.com/cemirror/inv/P-TB8-2-2.GIF[/img]

[img:500:133]http://www.tubesandmore.com/cemirror/inv/P-TB9-3-2.GIF[/img]

http://www.tubesandmore.com/scripts/fox ... POXYBOARDS

[FunkyE9th]

I've been thinking of using these.. http://apexjr.com/images/coloredposts.JPG but haven't gotten around to it. It's a dollar a piece so it gets expensive quick.

[davent]

More ideas.

http://www.angelfire.com/electronic/fun ... rding.html
http://www.angelfire.com/electronic/fun ... be_BB.html
http://home.polstra.com/amps/breadboard/

dave

[DonMoose]

So, in that TubeLab setup, what are the modules made of? The breadboard is perf'd plastic, but the blocks are ... ?

[a_e_a]

Hey guys thanks for the info!
some great ideas there and exactly what i was looking for.

I was never looking to use a standard breadboard like on the beavis. (i dont want to die haha) just liked the concept of nondestructive building and testing. I realize it is still a lot of work but putting something together and being able to try different things will teach me more than building amp after amp imo.

It is all well and good to read all the theory and what other people think does what but you gotta experiment yourself to figure out what things sound like. especially as tone is so subjective.

Thanks again for all the help! I'm sure I will be able to build something from the ideas here. Ill be sure to post once I do in case anyone else is interested...

Also keep posting if there are more ideas around!! Can never have too much info!!

Cheers

[Cliff Schecht]

This is where the term breadboarding came from, people literally taking their bread boards, putting a bunch of nails and terminal strips down, and wiring everything up point to point. Pic from Pete Millett's site.

[img:552:736]http://pmillett.com/images/EL34BB.JPG[/img]