for those that have done it, how do you get from admiring an amp to designing and building one?

[beckstriad]

Something that has always been interesting to me is how a builder starts working on amps and how that translates into designing your own circuit or refining an existing one. I’d be interested to know how you go from looking at other designs and then want to make your own and how that process unfolds. How do you know what to do?

 

[Voodoosound]

I can only tell you from a players perspective. I get ideas of what I want built by curiosity of “what if”. It’s usually well thought out from a what I want it to do and why I think this design will do it. I’d say I have about a 90% success rate with my ideas. For that other 10% I usually get told by the people I am asking to build my ideas that’s probably not going to work. In some cases I have it built anyway. At least I used to. And sure enough. Yeah, didn’t work how I perceived. By on very rare occasion those don’t do it ideas work even better than I expected.

Now since I don’t build amps I refer to those I call experts and even legends in this field. You and I are both lucky to know these people and in many cases call them friends. Hopefully, one or some of them will come here to answer your question better than I.

 

[jkelley]

Well, the answer to this question would probably be different for everyone, but for me it's a very long story that started with an interest in radios and electronics at about 8 years old. I got an electronics kit for Christmas and wired little circuits and built crystal radios. Someone gave me an ARRL Handbook that had explanations of DC circuits and how resistors and capacitors reacted to the flow of current. This helped me to gain a gut instinct for what these things actually did.

In high school I took an electronics class and got an after school job at a TV repair shop where I learned how to fix TV's. By then I started playing in bands and formed an acquaintance with guitar amps. In college I studied electronics, had a radio show at the student radio station, and continued working part time for TV repair shops. When I graduated I was offered a job at a Palm Springs TV station as a video engineer. I ended up repairing TV cameras, studio consoles, and 2" video tape recorders - and I started playing in bars.

That lasted a couple more years until I moved back to Orange County to start work at Music Man as production line tech. I learned how to manufacture guitar amps there. I got along well with everyone there except Forest White - and he ran the place (or at least he thought he attempted to). He kicked me out the door, and about a year later Tommy Walker kicked Forest White's butt out the door.

So being unemployed I started playing in clubs around OC and began doing repairs for music stores on the side. Eventually it became apparent that I wasn't going to become a rock star so I contacted Dale Fortune about renting space for a test bench in his shop. I began doing repairs and mods for the players who did business with Dale. Called the business Active Guitar Electronics. I learned how changes to circuit components affected the sound and how it looked on the oscilloscope. Heard a lot of different guitar amps as they came in for various things - boosting gain, adding post phase inverter master volumes, noise problems, tone problems etc.

Mesa Boogie amps began proliferating at that time and I was not a fan of the sound of their kazoo-like pre-amp distortion. None of the master volume amps of the day sounded good to me, so there was need of something better. A niche. One day someone brought in his beloved Ampeg SB-12 portaflex amp. He used it for guitar and loved the sound of it, but his girlfriend had decorated the amp with a potted plant in their home. One day water and soil from the plant overflowed down into the amp chassis. When she turned the amp on to see if any damage had been done sparks and flames erupted. I determined that both of the transformers had fried. But at the time replacement transformers for older Ampegs were not available, and on top of that the amp used these weird output tubes - 7868's, which I couldn't get. A complete redesign of the power supply and output section was needed. When all the final tweaks were completed it sounded absolutely glorious, and I had every guitar player who came through the shop plug into it. As they played I studied how the signal looked at each stage as it progressed through the amp. The thing I learned was that it stayed absolutely clean all the way through the amp and didn't clip until it hit the output tubes. (At the time this was a revelation.) The push-pull output section produced the kind of overdrive everyone seemed to prefer over the overdriven class A preamp tubes. The early Fortune amps were basically replicas of that modified amp.

Of necessity I designed a power attenuator to act in lieu of a master volume. I then added reverb. Next iteration I added a duplicate preamp and channel switching, and eventually started experimenting with the Line Amp idea. The old adage is 'necessity is the mother of invention' - and it's true. Identify a need and work the problem until the solution is found.

 

[Voodoosound]

Great information Jim. Thanks for sharing.

 

[TimAE]

This is kind of a neat topic. To echo Jim above, I'm sure everyone starts with some affinity for things that make sound and sparks. As a child I also had quite the fascination with music and the mechanisms that created/transmitted it. We were pretty poor when I was a child so getting fancy trinkets wasn't exactly in the cards. Christmas toys that ran on batteries were destined for the makeshift "workbench" in my bedroom as when the batteries ran out,... rarely did more batteries arrive. So, inevitably, I'd begin some sort of disassembly with two things in mind: 1. How does this thing work; and 2. Is there a way to plug it in? Needless to say, I tore up a lot of stuff and had my share of electrical stimulation - if you will. Fast forward to adulthood where I earned my BSEE in the Navy, and subsequently worked as a Sr. Petroleum Engineer for several Oil Service and Completion companies, I was able to get quite the good electrical / chemical education with resources to also satisfy my tinkering habit that never ceased.

I had learned to play guitar and drums as a kid. Been in a few talent deficient bands, owned some recording outfits, production junk, yada, yada. ALWAYS making and listening to music, rarely watching TV at all. In recent years, I've ditched the TV altogether. Don't even own one. So, I immerse myself in electronics, gadgets, music or silence, most of the time. Around late 2007, I was working a rotation in the Northern Slope of Alaska (Prudhoe Bay) and was online shopping for a vintage Vox AC30. I verbally expressed my disgust that even ones that looked like they were drug behind a truck for 15 years were still going for $2,000 at that time. A colleague of mine overheard me whining and asked a couple key questions to me. "Hey, aren't you an electrical engineer?" I replied, "yes". "Then why don't you just build your own?" Silly how that never occurred to me. Which is probably why I couldn't figure out how to make the old 4-track that ran on 8 D-cell batteries run on 115VAC as a kid. So,..... I found and downloaded RCA Radiotron handbooks and went to work on a small and quick design - just to prove concept. I bought a Crate V5 donor for chassis and iron, built a small 1x10 cabinet out of poplar, and found a used Celestion G10 on Ebay. I had maybe $80 in it, including the excessive glue and finish nails.. Wired it up,... screwed it together,... plugged it in,...... flipped the switch. Holy shit - nothing caught fire. It really didn't sound that great, and there was some pretty decent noise floor, but hey! It Worked!!

From there two major points in my life collided. The need for music and the need to constantly tinker. Shortly later, my serial entrepreneurship kicked in as well. With guitar amplifiers, I wanted to do things a bit different. I at least wanted to start with a desired outcome and work my way backwards simply using whatever it takes to set-up the equipment to work. There's nothing truly new under the sun, and I know that, but, I at least wanted to say it wasn't "based" on anything, or a copy of...... Just trying some new recipes over here. I hope to make people smile and forget how to talk every time they turn one up. Once in a while, I get one right.

Cheers.

 

[beckstriad]

Well, the answer to this question would probably be different for everyone, but for me it's a very long story that started with an interest in radios and electronics at about 8 years old. I got an electronics kit for Christmas and wired little circuits and built crystal radios. Someone gave me an ARRL Handbook that had explanations of DC circuits and how resistors and capacitors reacted to the flow of current. This helped me to gain a gut instinct for what these things actually did.

In high school I took an electronics class and got an after school job at a TV repair shop where I learned how to fix TV's. By then I started playing in bands and formed an acquaintance with guitar amps. In college I studied electronics, had a radio show at the student radio station, and continued working part time for TV repair shops. When I graduated I was offered a job at a Palm Springs TV station as a video engineer. I ended up repairing TV cameras, studio consoles, and 2" video tape recorders - and I started playing in bars.

That lasted a couple more years until I moved back to Orange County to start work at Music Man as production line tech. I learned how to manufacture guitar amps there. I got along well with everyone there except Forest White - and he ran the place (or at least he thought he attempted to). He kicked me out the door, and about a year later Tommy Walker kicked Forest White's butt out the door.

So being unemployed I started playing in clubs around OC and began doing repairs for music stores on the side. Eventually it became apparent that I wasn't going to become a rock star so I contacted Dale Fortune about renting space for a test bench in his shop. I began doing repairs and mods for the players who did business with Dale. Called the business Active Guitar Electronics. I learned how changes to circuit components affected the sound and how it looked on the oscilloscope. Heard a lot of different guitar amps as they came in for various things - boosting gain, adding post phase inverter master volumes, noise problems, tone problems etc.

Mesa Boogie amps began proliferating at that time and I was not a fan of the sound of their kazoo-like pre-amp distortion. None of the master volume amps of the day sounded good to me, so there was need of something better. A niche. One day someone brought in his beloved Ampeg SB-12 portaflex amp. He used it for guitar and loved the sound of it, but his girlfriend had decorated the amp with a potted plant in their home. One day water and soil from the plant overflowed down into the amp chassis. When she turned the amp on to see if any damage had been done sparks and flames erupted. I determined that both of the transformers had fried. But at the time replacement transformers for older Ampegs were not available, and on top of that the amp used these weird output tubes - 7868's, which I couldn't get. A complete redesign of the power supply and output section was needed. When all the final tweaks were completed it sounded absolutely glorious, and I had every guitar player who came through the shop plug into it. As they played I studied how the signal looked at each stage as it progressed through the amp. The thing I learned was that it stayed absolutely clean all the way through the amp and didn't clip until it hit the output tubes. (At the time this was a revelation.) The push-pull output section produced the kind of overdrive everyone seemed to prefer over the overdriven class A preamp tubes. The early Fortune amps were basically replicas of that modified amp.

Of necessity I designed a power attenuator to act in lieu of a master volume. I then added reverb. Next iteration I added a duplicate preamp and channel switching, and eventually started experimenting with the Line Amp idea. The old adage is 'necessity is the mother of invention' - and it's true. Identify a need and work the problem until the solution is found.

Really appreciate you giving such a detailed answer, Jim. How similar are the Fortune amps in design to your original single channel reverb amp?

 

[beckstriad]

This is kind of a neat topic. To echo Jim above, I'm sure everyone starts with some affinity for things that make sound and sparks. As a child I also had quite the fascination with music and the mechanisms that created/transmitted it. We were pretty poor when I was a child so getting fancy trinkets wasn't exactly in the cards. Christmas toys that ran on batteries were destined for the makeshift "workbench" in my bedroom as when the batteries ran out,... rarely did more batteries arrive. So, inevitably, I'd begin some sort of disassembly with two things in mind: 1. How does this thing work; and 2. Is there a way to plug it in? Needless to say, I tore up a lot of stuff and had my share of electrical stimulation - if you will. Fast forward to adulthood where I earned my BSEE in the Navy, and subsequently worked as a Sr. Petroleum Engineer for several Oil Service and Completion companies, I was able to get quite the good electrical / chemical education with resources to also satisfy my tinkering habit that never ceased.

I had learned to play guitar and drums as a kid. Been in a few talent deficient bands, owned some recording outfits, production junk, yada, yada. ALWAYS making and listening to music, rarely watching TV at all. In recent years, I've ditched the TV altogether. Don't even own one. So, I immerse myself in electronics, gadgets, music or silence, most of the time. Around late 2007, I was working a rotation in the Northern Slope of Alaska (Prudhoe Bay) and was online shopping for a vintage Vox AC30. I verbally expressed my disgust that even ones that looked like they were drug behind a truck for 15 years were still going for $2,000 at that time. A colleague of mine overheard me whining and asked a couple key questions to me. "Hey, aren't you an electrical engineer?" I replied, "yes". "Then why don't you just build your own?" Silly how that never occurred to me. Which is probably why I couldn't figure out how to make the old 4-track that ran on 8 D-cell batteries run on 115VAC as a kid. So,..... I found and downloaded RCA Radiotron handbooks and went to work on a small and quick design - just to prove concept. I bought a Crate V5 donor for chassis and iron, built a small 1x10 cabinet out of poplar, and found a used Celestion G10 on Ebay. I had maybe $80 in it, including the excessive glue and finish nails.. Wired it up,... screwed it together,... plugged it in,...... flipped the switch. Holy shit - nothing caught fire. It really didn't sound that great, and there was some pretty decent noise floor, but hey! It Worked!!

From there two major points in my life collided. The need for music and the need to constantly tinker. Shortly later, my serial entrepreneurship kicked in as well. With guitar amplifiers, I wanted to do things a bit different. I at least wanted to start with a desired outcome and work my way backwards simply using whatever it takes to set-up the equipment to work. There's nothing truly new under the sun, and I know that, but, I at least wanted to say it wasn't "based" on anything, or a copy of...... Just trying some new recipes over here. I hope to make people smile and forget how to talk every time they turn one up. Once in a while, I get one right.

Cheers.

Thanks for sharing that, Tim. When you were working as an engineer, were you building or repairing amps the whole time? Or was the AC30 your first foray into anything amp building related?

Did electrical engineering school teach you to work on electronics (soldering and the like)?

 

[Voodoosound]

Thanks Tim. Great insight.

 

[TimAE]

Thanks for sharing that, Tim. When you were working as an engineer, were you building or repairing amps the whole time? Or was the AC30 your first foray into anything amp building related?

Did electrical engineering school teach you to work on electronics (soldering and the like)?

I didn't actually build an AC30. I was just looking to buy one. I ended up building a 30 watt 6L6 amp as my first "real" amplifier build. I learned electronics working in the Navy as an FC (Fire Controlman). I performed maintenance on radars, weapons guidance, gun and missile systems.

 

[beckstriad]

I didn't actually build an AC30. I was just looking to buy one. I ended up building a 30 watt 6L6 amp as my first "real" amplifier build. I learned electronics working in the Navy as an FC (Fire Controlman). I performed maintenance on radars, weapons guidance, gun and missile systems.

That’s incredible. What would you recommend as a good starting place for someone with no electronics experience to learn how to work on an amp?

 

[TimAE]

It's always a good idea to learn what the basic components do, at least in a generic way. If you understand what resistors, capacitors, inductors, transformers and tubes do, you can then understand how those components can work together and against one another. Building an amp is a lot of give and take. from there, learn ohms law to some degree and how to use the basic tools- multi-meter, soldering iron, etc. Then just go to mojotone, weber, ceriatone, or many of the other amp kit vendors out there and build a Fender 5E3. They're easy and very tweakable, so you can see how changing particular component values affects the performance of the amplifier.

 

[beckstriad]

It's always a good idea to learn what the basic components do, at least in a generic way. If you understand what resistors, capacitors, inductors, transformers and tubes do, you can then understand how those components can work together and against one another. Building an amp is a lot of give and take. from there, learn ohms law to some degree and how to use the basic tools- multi-meter, soldering iron, etc. Then just go to mojotone, weber, ceriatone, or many of the other amp kit vendors out there and build a Fender 5E3. They're easy and very tweakable, so you can see how changing particular component values affects the performance of the amplifier.

thanks for sharing. I have always been interested in learning how that stuff works. That sounds like good advice for getting going.

 

[willie k]

Mojotone offers a 5E3 build course. I don’t know much about it, but I have seen it advertised. You basically build their kit with guidance. They promise a completed working amp.

As far as soldering goes, the main points are make sure the unit is unplugged, and heat your work, not the solder. The solder will flow onto the heated work. Do not move the work until it cools. A proper flow will be shiny when it cools. Keep the tip of the iron clean. Use no more heat than necessary. With a little practice you will be soldering like a pro. I find it therapeutic.

 

[beckstriad]

Mojotone offers a 5E3 build course. I don’t know much about it, but I have seen it advertised. You basically build their kit with guidance. They promise a completed working amp.

As far as soldering goes, the main points are make sure the unit is unplugged, and heat your work, not the solder. The solder will flow onto the heated work. Do not move the work until it cools. A proper flow will be shiny when it cools. Keep the tip of the iron clean. Use no more heat than necessary. With a little practice you will be soldering like a pro. I find it therapeutic.

That would be really fun and interesting. I will hopefully find the time one of these days.

 

[Geetarman74]

This is one of the most interesting and enjoyable threads I’ve ever read on any forum. Sincere thanks to Jim and Tim for the biographies and insights!

The amps both of you have made for me represent the pinnacle of 30+ years of searching for the perfect amp.

 

[jkelley]

Really appreciate you giving such a detailed answer, Jim. How similar are the Fortune amps in design to your original single channel reverb amp?

Sorry for the late reply. I just now saw your question. The only difference was the front panel.

 

[beckstriad]

@Stark I would love your input as well.