Tube amp....It's alive....and so am I!

scott spencer

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Rochester, NY
Last October I finished my first electric guitar for my 16 year old son. http://sawmillcreek.org/showthread.php?t=43739&highlight=guitar
We were encouraged enough by the sound that we thought it merited a tube amplifier, but the CFO (LOML) wouldn't "buy" into our enthusiasm :bang:. The fiscally acceptable solution was to build one....a 3 watt, Class A "night light" from mostly salvaged parts. We used the chassis and power transformer from a 1939 Stromberg Carlson radio. This project has me way out of my element, but after several weeks of headscratching, several revisions to the schematic, and several feet of solder up in smoke, she finally glowed and sang to us tonight! Woo Hoo! :guitar: :D

It seemed like every tube amp website I looked at had huge "WARNINGS!" about how the high voltages of these things can kill you if you don't know what you're doing. :eek::dunno: So with one hand safely tucked in my pocket, I poked and prodded enough to gain some confidence that this thing wasn't wasn't going to become a turbo charged pacemaker for anyone. All systems go so far, but there's still much work to be done. The plan is to clean up the layout, then stuff the whole thing in a box from a 1928 American Bosch radio. I'll post some pics once it's presentable.....right now I'm just happy that it works and that no one got fried! :thumb:
 
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Awesome. The guitar thread definitely belonged in the OT forum, but I think maybe this thread should go in the Neander forum. Very few people make their own tube amps. When you figure out how to convert a woodworking lathe into a LP cutting lathe to cut your own records, that one goes in the Turning Forum.:thumb:
 
Cool news to see you got 'er done, Scott. I'll bet it sounds nice and rich at lower volumes, and good and crunchy when it's cranked up.

Regarding the high voltages, I learned about that (and about how capacitors store electricity) as a teenager replacing the power switch on my old Fender Deluxe Reverb. I had unplugged it, and was in the process if removing the broken switch, when my hand bumped something and ZAP! I was given a healthy shock. I scratched my head, double checked to see that it was unplugged, the went back after the switch. ZAP! again. I was thoroughly confused, since I couldn't figure out what I was touching to get the shock, and how I was getting shocked after unplugging the amp.

Long story short, I found that the clipped-off end of one of the wires to the switch was still hot, and my hand had been brushing against the little bit of copper that was exposed on the end of the wire. When I finally tracked it down and put my voltmeter on it, it still had several thousand volts hanging around in the capacitor, waiting for the next ZAP! :eek:
 
Question...

Thanks for the "plug" gang! :laugh2: Many thanks to Tom Pritchard and Ahmet Becene for answering countless questions. :headbang: I'd probably have curly hair and Marty Feldman eyes if not for you guys! :eek:

QUESTION FOR YOU GUITAR PLAYERS: :guitar: (love that emoticon! ...wonder who's idea that was Vaughn?! :D )

This amp lacks reverb. Danelectro has some effects pedals for < $20...my son has the "Overdrive" and "Distortion" pedals, which he likes....which of their pedals is closest to reverb..."Echo" or "Chorus"? ...and what's the "Flange" do?

There's a pic of the box she's going into below:
 

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Echo would be the closest to a Reverb. Both Chorus and Flanging also have pitch bending involved which doesn't sound much like Reverb. You could probably pick up a Spring Reverb Unit specifically made for guitar amps for next to nothing though.
 
Sounds like a fun project, Scott.:thumb: But I am curious as to why you wanted a tube amplifier in this day a age, other than the parts were available at the right price.;)
 
Sounds like a fun project, Scott.:thumb: But I am curious as to why you wanted a tube amplifier in this day a age, other than the parts were available at the right price.;)

Tubes have a distinctive sound character that you can't get from transistors IMO....plus tubes glow in the dark! The tube sound is often richer and sweeter, and has better resolution of fine detail than transistors. I'm pretty new to guitar amps and the tube appeal to that application, but tubes also have a more refined character when they get driven past their normal operating capabilities and distort...they distort alot more gracefully. Distortion can be a desirable sound in a guitar amp, and the circuitry is often developed with high gain in mind so the distortion can be minimized/maximized with a knob or a switch. Distortion in a solid state amp has to added with a separate electronic circuit and it's just not the same.

As always, which you "like" best is a matter of opinion, but I'm definitely a tube fan. Tubes are alive and well in the highend audio world, and are very popular as musical instrument amplifiers. They will usually fetch a premium, and there's still a huge market willing to pay for the tube benefit.
 
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scott, not to sidetrack your thread.....(i can`t play any insturment) but tube amps are considered by many to be the absolutely best way to reproduce sound and even with my ol` deaf ears i`ve gotta agree...if a fellow ever gets a chance to hear a good tube amp run through good speakers he`ll most likely not be happy with the ic amps everybody makes now ever again..
 
Gentlemen, I think I have heard that song before.:D

Let me give you my position, and then let's let it go, OK?

A tube amp by necessity requires an output transform to match the high impedance of the output tubes (3 to 6 thousand ohms) to the low impedance of the speakers (4 to 16 ohms.) A transformer is an inductor, and as such has a built-in shock absorber type response.

A transistor output is by its nature a low impedance output, may be even lower than one ohm. There is no output transformer to get in the way.

The name of the game in amplifiers and speakers is for the amp to put the speaker cone where it wants it and at the time it wants it. Ideally you would want your amp almost touching the speaker cabinet in order to keep the impedance between the amp output and the speaker cone to an absolute minimum. Of course, that would produce some undesirable effects like micro phonics or even feedback.

Due to its output transformer, a tube amp by nature cannot provide the tight control of the cone that a low impedance transistor output can. As a result you get "mellow" sound instead of the crispness of a transistor output.

Sure there are people who like "mellow" sound, and some are even willing to pay $24,000 for a tube amp, and over $10,000 for a preamp. I wonder if those people get their entertainment from spending the money rather than from using the equipment.

Then there is distortion. Introducing a distortion generating device into the amp input makes all of our discussion a moot point. The seems to be a tendency to take a guitar, give it to a simulation of a human being that needs a haircut, bath, and rehab, to see how many unnatural sounds can be generated. (What a roll model!) The last great guitarist was Chet Atkins, the rest need to take some lessons in the proper use of the instrument.


So who is getting the best sound? In the final analysis, we both are because we are hearing what we each regard as the better sound.

It has been nearly 50 years since I built a tube type amplifier, a pair of KT88s with 12AX7s driving, and with a good old Heathkit preamp running the show. One Christmas break I built a Carlson speaker cabinet out of 3/4" oak plywood. (The first time I used Waterlox for a finish.) Why a Carlson design, because their ads in the mags said "a box is not a musical instrument."

At last I am done bloviating. This post is worth what you paid for it.

Your neighborhood curmudgeon.:wave:
 
Sounds like a fun project, Scott.:thumb: But I am curious as to why you wanted a tube amplifier in this day a age, other than the parts were available at the right price.;)
Ken, to add to what Scott said, tube amps generally emphasize the odd-numbered harmonics (1st, 3rd, 5th, etc.) whereas a solid state amp generally emphasizes the even-numbered ones. To the human ear, the odd-numbered harmonics sound more pleasant. The vast majority of professional guitarists use a tube amp on stage and in the studio.You'll also find that many high-end audiophile stereo systems use tube preamps and/or power amps. They are much more expensive, but they sound better in most peoples' opinions.

However, in the past 10 years or so, there have been great strides made in using solid state circuitry to emulate a tube amp. I really like (and own several) tube amps, but nowadays when I'm playing at home, I run through one of several solid state "amp modelling" devices I have that do a very credible job of sounding like some of the more popular tube amps. The beauty of these devices is that in a box the size of a couple packs of cigarettes, I can have the sounds of dozens of different amps, just a knob turn or button push away. (I've got a Pod 2 and GuitarPort from Line 6, and the Black Box from M-Audio. And my Mesa Boogie, Fender, and Music Man amps are gathering dust.) If I were still playing on stage, I'd probably still be running a tube amp rig, but for my office/studio at home, the solid state devices and a pair of headphones can make me sound like I'm in an arena plugged into a wall of Marshalls. :guitar: :headbang:

Scott, as Doug said, the echo pedal will be closest to reverb, but I don't think the little $20 Dan Electro version will really have a credible reverb. It looks to be more strictly an echo box, which can still be a lot of fun to play with. Personally, I use a chorus effect more than reverb, but that's simply my tastes. And to answer your "flanger" question, flanging is similar to chorus effects in that it splits the signal then slightly delays part of the sound. The most common "flanger" sound is like the guitar in Heart's "Barracuda", where it sounds like it's going through a tunnel or something. A chorus is more subtle...a lot of U2 guitar work has some chorus on it. Jazz player Pat Metheny has made the chorus sound his trademark, as have many other players.

HTH -
 
Sounds like a fun project, Scott.:thumb: But I am curious as to why you wanted a tube amplifier in this day a age, other than the parts were available at the right price.;)

It's hard to play with cold hands. Those of us that live in colder climates would look pretty stupid trying to warm our hands over glowing transistors. :D
 
Hi Vaughn,
I think what you meant to say was tube amps generally emphasize even order harmonics, sand amps emphasize odd order harmonics. To the human ear, even order harmonics sound pleasant.

Rawk on! :)
 
Hi Vaughn,
I think what you meant to say was tube amps generally emphasize even order harmonics, sand amps emphasize odd order harmonics. To the human ear, even order harmonics sound pleasant.

Rawk on! :)
Yeppers, I stand corrected. It's been a while and I'm rusty. :doh: :eek: Found an interesting read while Googling "tube amp" +harmonic...

http://www.trueaudio.com/at_eetjlm.htm

Based on the article, looks like I may also stand corrected on some of my statements about the "vast majority" of pros using tube amps for performances. ;)

Thanks for the re-edumacation. :)
 
Jazz player Pat Metheny has made the chorus sound his trademark, as have many other players.
Haven't heard much of his stuff lately, but at one time he was a bit more "high-tech" than that: using a MIDI-equipped Yamaha(?) guitar to trigger synths and/or samplers. The scary part was how he could get the phrasing right for things like sax or trumpet sounds.
 
The seems to be a tendency to take a guitar, give it to a simulation of a human being that needs a haircut, bath, and rehab, to see how many unnatural sounds can be generated. (What a roll model!) The last great guitarist was Chet Atkins, the rest need to take some lessons in the proper use of the instrument.
Uh, I'll see your Chet Atkins and raise you Lee Ritenour, Al DiMeola, Larry Coryell, Phil Upchurch, Paul Jackson Jr.,...
 
...Then there is distortion. Introducing a distortion generating device into the amp input makes all of our discussion a moot point. The seems to be a tendency to take a guitar, give it to a simulation of a human being that needs a haircut, bath, and rehab, to see how many unnatural sounds can be generated. (What a roll model!) The last great guitarist was Chet Atkins, the rest need to take some lessons in the proper use of the instrument.
...
Personally, I enjoy the challenge and artistic possibilities from modifying the straight guitar tone with all sorts of electronic devices, which are all doing some form of distorting or modifying the sound. Like anything with more than three knobs, there are more bad settings than good settings, but I like trying to find the good ones. The "plain" guitar sound is just one possibility. In my final analysis, it's just six variable waveform generators attached to a chunk of wood and metal. What you do with the resulting waveforms is subjective from that point forward. If you want natural sound, get an acoustic guitar. :)

And I gotta say I'm a little put off by your characterization of guitarists as needing a haircut, a bath and rehab. My hair length is my choice (I cut it off, and the good Lord keeps putting it back on), I bathe at least once daily, and I got over the drug thing decades ago. Without rehab. (And I don't drink, either.) I've also got a lot of kids that were my students (and their parents) who would argue my status as a positive role model. ;) No worries though, you're entitled to your opinion.

And Chet was indeed one of many great guitarists, IMHO. :thumb: He'd be the first to admit there are many others, though.
 
OK Vaughn, the hair and bath was an exaggeration. But, there are a lot of xxx-rock groups that I surely would not want to be around.

Regarding the distortion, it is just "junking" up what is a beautifully sounding instrument when played in the traditional way.

I guess I am just showing my age, but it seems to me that the rock scene went to pot(literally, and figuratively) in the 70s. Give me the Mommas and the Papas and music that is identifiable as music instead of mindless beating on a guitar.

I forgot to mention, Andres Segovia is probably the best guitarist I have ever heard. Mastering the Spanish classical guitar is to me an amazing accomplishment. OK, he is better than Chet, but Chet is a darn close second.

One last thought, if an amplifier is not exactly reproducing the input given to it, it is not doing its job, be it "bottle," or "sand" based. Let the preamp apply the device compensation necessary.

So what do I listen to? In the shop and car it is KHYI country and western, KLUV olde and goodies, and WRR classical. Each has a website and broadcasts over the Internet.

Now that I have totally insulted the under 55 group, I will desist.

Curmudgeon at large, call the men in the white suits.:rolleyes: :eek: :D
 
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