For the new builders

[Luthierwnc]

I have seen a number of new folks logging-on and being interested in building a "D" as their first DIY amp. This a great hobby. I have certainly enjoyed making and playing my own stuff.

There is one caveat, these are very complicated amplifiers and probably not the best "first" amp. Space is at a premium in these chassis'. There are a lot of things that affect the tone and a lot of things that can make or break the project -- even with the layouts and advice available here. If I could offer an avuncular suggestion, build something simple for your first amp. There are lots of sites that specialize in some very cool circuits that include everything you need for a successful project.

I am certainly not the most knowledgable guy here but I have been soldering for about ten years. I have learned about every hum, squeak, squeal and notch that a badly made amp can produce. Over time, I have learned to fix them. I also know which ones are which and the where to start looking. Other things include how much room different components actually take, keeping some wires away from others, a system for checking every solder joint, a system for checking your layout diagram and a system for double-checking the soldered amp with the schematic. You have to do the same for a Spitfire or an HRM.

If you are determined to make your "D" first (which is a worthy ambition and much better than not making anything), try to build and test it in stages. Hardwire the clean channel directly to the PI and make sure it is dead clean with no hums, clicks or buzzes. Check your voltages, check your physical connections, get the bias right. Don't stop until it sounds great. Then add in the relay supply and OD (remember, most of the relays we use will be normally-closed in the clean mode when inactive). If there is a problem, you know where it isn't. Same for reverbs and active loops.

Above all, make your safety procedures habits. My soldering iron is plugged into an outlet strip along with one of the work lights. The light switch is taped permanently on. If it is shining, the iron is hot. All work pieces are plugged into a variac in parallel with a red Xmas light. If that light is on, the amp is hot. It isn't such a big deal with these circuits but I have an alligator clip on a wire with a 2Watt insulated 10k resistor on the other. It is clipped to the chassis and I hit the rail a couple times after it has been on to bleed the caps. Know when to use a screwdriver and when to use a chopstick. Keep your left hand off the chassis. Put a little fan on the same strip as the soldering iron so you don't have the fumes come up in your face. Ask a lot of questions.

Sorry for the rant but you might find something useful in it. If you get the itch, you are going to make more amps anyway. If you can make a Wreck or JTM45 or tweed sound great, you'll have covered a lot of the bases. When you get to the "D", you'll understand the refinements.

Skip

[Bob-I]

If you are determined to make your "D" first (which is a worthy ambition and much better than not making anything), try to build and test it in stages. Hardwire the clean channel directly to the PI and make sure it is dead clean with no hums, clicks or buzzes. Check your voltages, check your physical connections, get the bias right. Don't stop until it sounds great. Then add in the relay supply and OD (remember, most of the relays we use will be normally-closed in the clean mode when inactive). If there is a problem, you know where it isn't. Same for reverbs and active loops.

The only difference I'm mention is to do the relays later. Hard wire the OD side and make sure that's working perfectly, as Skip described above.

Above all, make your safety procedures habits. My soldering iron is plugged into an outlet strip along with one of the work lights. The light switch is taped permanently on. If it is shining, the iron is hot.

Good idea. Another one, the one I use is to have a soldering station that shuts off after a set time period.

All work pieces are plugged into a variac in parallel with a red Xmas light. If that light is on, the amp is hot.

I disagree with this one, because it doesn't tell you when the amp is plugged in. I have an outlet right on my work surface and I don't put my hand in there until I have the cord in my hand.... let me repeat I HAVE the cord, not someone else.

Keep your left hand off the chassis.
Skip

Very important!! I'm left handed and it's hard at times but it's important because the left hand is closer to the heart.

Great post Skip!

[Luthierwnc]

You're right. I didn't word that well. Put all the components in (especially the ones that are easier to do before the board is bolted in) but activate and test them in order. The preamp/power amp is first. You are only testing the CL, PI and power tubes. I'll put the others in to sneak a peek at the voltage drop and draw but take them out for noise control. This tells you if any of the big stuff is wrong. Is everything grounded? Any weak solder connections? Did the bias cap explode? What is the heater voltage?

Then test the OD hard wired (jumpered), the relays and the effects. I don't do this as rigorously anymore but I am always prepared to undo things and test each part individually.

Thanks for mentioning the cord. My variac is the only outlet within reach (other than the soldering set-up) The little light is handy. When I turn out all the shop lights, a quick scan tells me if I am "burning in the tubes" unintentionally.

sh

[d95err]

Hi, I guess I'm one of those newbies, although I've actually already followed your advice and built a simple amp first. My first build was a MADAMP kit. They are dead cheap and very easy to mod - perfect for a first build.

In addition to just building a simple amp, I think it's really important not to settle there, but to tweak it and mod it and tweak it again... That's the only way to really learn how different components affect the sound of the amp.

On the theory side, I've used three major sources of information:

1. Web forums (this forum, 18W forum, AX84)

2. I read just about everything from Schematicheaven and tried to figure out how every amp worked

3. Kevin O'Connor's book "The Ultimate Tone". I'd say that's the perfect book for someone who wants to learn about amp building and modding without having to get an Electric Engineering degree first.

[mr_chrish]

This is one of the best posts I've read, and I've been reading every other day for the last month or so. I've been looking for a sort of A-B-C, wondering what order to do things in, finally found some answers! I also like that you encourage us newbies to build and be merry, to try things out and ask as we go along. So a couple of questions:

1. I want to start "light". Is it possible to start with a hybrid A based model with just a clean channel and no reverb and effect loop?

2. If that works, then I can ad more later?

3. How complicated is a reverb circuit? (Is there such a thing as a 'reverb circuit') What kind of parts would I need?

Thanks,
Christian

[Bob-I]

1. I want to start "light". Is it possible to start with a hybrid A based model with just a clean channel and no reverb and effect loop?

You could do that.

2. If that works, then I can ad more later?

You'd have to plan for that. I often build in sections, but you have to plan the layout before starting or it'll never work out.

3. How complicated is a reverb circuit? (Is there such a thing as a 'reverb circuit') What kind of parts would I need?

Thanks,
Christian

Not terribly complex but by the time you start adding these things in the amp becomes pretty complex.

[mr_chrish]

Hm, looks like it would be just as easy to follow the hybrid schematic and maybe test things as I go along.

Thanks,
Christian

Btw, got a chance to talk to Mike Stern today, he was giving a clinic at the local jazz festival. It was my first time talking to a guitarist of that caliber, althought it was just for a minute or two I really enjoyed it. He seems like a nice guy.

[Luthierwnc]

I think a Hybrid A with no loop or reverb would be a good start. Although, without the overdrive it is basically a blonde Bassman. Put another way, without the overdrive it isn't an Overdrive Special. Your next project can be a reverb-o-loop!

I agree with Bob-I that you have to figure out where everything goes before you start. That is one of the most fun parts of the project -- designing the layout and selecting the components.

These steps are probably on another dedicated build site but you have to have a project agenda. First, select the schematic. Select the layout. Get a chassis to match the above and the appropriate faceplates. Get the rest of the parts. Don't be surprised if you need to reorder or have extra stuff for the parts bin. Put the heavy stuff (transformers, choke) on first. Protect the faceplates.

Complete as much of the component board as you can before you attach it to the chassis. Leave plenty of wire on the leads because what you drew as a straight line takes a lot more wire in 3D. Pre-wire anything that will be hard to access when it is attached. Double shrink tube high voltage connections. They aren't rated for 450 volts.

Write your steps down and check them off as you go. When I am soldering, I break it down in sections and try to commit enough time to complete each module. First tube, second tube, filaments, power caps -- you get the idea.

I think the most important thing is to allow yourself some slack for on-the-job training. You will learn more than anyone could tell you by the time you are done. Pick an amp and go for it. One of the real joys in life is the first time your neighbor yells, "Hey, cut that f%&*@G! thing down!"

Skip

[mr_chrish]

Thanks again, great tips.

But I want to make shure I understand things right before I start,

1. I want to go for the Hybrid A with no reverb or loop. But the overdrive is still there?

2. Is there any schematic with the reverb and loop removed, or is that easy enought for me to do myself?

3. How big is the Hybrid A? 100w? If so, I really don't need all that power. Is it possible perhaps save both parts and money on building a 50w or a 75w? I'm really in the dark here, this might be way off.

Thanks,
Christian

[Luthierwnc]

Yes, Hybrid A with OD but no loop or reverb. The schematic doesn't show either of those. Glasman's reverb-o-loop is a very cool project and will handle the effects duty brilliantly -- just be sure to put send and return jacks in the back of the amp.

The posted schematic calls for a pair of 6L6 tubes which are good for 40-50 watts, depending on who you ask. 100 watts is probably a little too ambitious for a first effort. sh

[skyboltone]

Skip:
I think that your initial post in this thread is right on. Some weeks ago, Omar instituted the amp-wiki site and there is nothing in it so far as I can tell. I suspect that the reason is that it's voluntary. Most of us aren't willing to jump in there an post our own articles. That's why we need a nomination procedure.

I nominate your initial post, or some such expandification of it.

Respectfully putting you on the spot, I remain, your
pal....sorry.

Dan

[Luthierwnc]

How flattering! It is all in the public domain. I rate myself 6-7 on the electronic theory. 8ish on scratch build technique. Mostly I hang around trying to bone up on the former and share a few shop tips.

If I ran the world, I would just have people get their Bachelors at AX84 or 18-watt and come here for their post-graduate work. Those sites are more geared to include process in the build -- BOM, what to do first, etc.

My main thrust was that even the simplest amps can: motorboat, oscillate, yowl, squeak, squeal, spark or channel radio stations. After enough years of shocking yourself, you know more or less what those noises mean and where to start looking for the problem. When the amp is humming like it doesn't know the words, the tonal difference between a Xicon and an Orange Drop on V1b might elude you.

You don't have to start with a klunker, either. The best amp I've made in years is a copy of the DR Z Z28. Two preamp tubes, three knobs. The turret board looks like a desert compared to a "D". Over a single 12 it is just magic. You can figure it out from the acplink page. It is the one in Walnut. The one above is a Route 66 clone which is identical except for the power section. Point being, you can make a really good amp and learn the basics on the first try and move up to the bigs on the next. sh

[Bob-I]

Beautiful stuff Luthierwnc. I get by on the building part but I'm no craftsman on the cabinets My Peavey cabinet was eaten by a groundhog while I was letting the tolex glue dry.

[Normster]

Yup, gorgeous...and you haven't even posted pics of the matching guitars yet!

[Luthierwnc]

The 336 was a gamble because I had no idea how to tune the cavities. They tap out nothing alike but it worked.

I've only made two truly matched sets of guitars. One pair was a classical and a steel string from the same plantilla and the same woods. If you look at the gallery on the Zia site in my profile there are a pair of left-handed, double-neck guitars I made for the Gagan brothers. They both played guitar and bass so instead of having to switch instruments, each had their own guitar rig and a single bass amp to share. Switches on the guitars controlled the output along with an A/B box on the floor. I only made one of the necks and all of the hardware was theirs. One likes single coils, the other buckers.

Some of you might recognize Tim and Joe Gagan as amp and FX builders in their own right. Joe made the prototype for these by cutting two instruments in half with a skill saw and gluing them together. It was called the evil twin. sh