Construction methods in tube instrument amps

A quick survey of the four main types of tube musical instrument amplifier construction methods (point-to-point, eyelet board, turret board, PCB). Rob from Auburn Amps discusses the pros and cons of each technique as they relate to manufacturers and hobbyists/small builders.

[@richardmerriam7044]

The military still uses vacuum tubes for some applications. I've been looking for a part time job soldering eyelet boards, and there is still some work out there.

[@bertrace4558]

Very informative and very well done! Thank you!

[@auburnamplifiers1786]

Thanks very much for your comment!

[@bretfuzz925]

Thanks. That was awesome. My worst nightmare amplifier was a true p-p. I would regularly have to take it apart and re-solder broken leads from vibration.

[@auburnamplifiers1786]

Thanks very much for this interesting and useful comment. True point-to-point was better suited to equipment that didn't get moved around much, like early consumer radios and TVs.

[@kaseysimons128]

enjoyable watch

[@CaptainRon1913]

It helps with these newer printed circuit board designs, if the board is on the bottom where the tubes can sit right side up and allow the heat to rise away from the circuit board. A very quiet computer fan could be placed in the cab to direct the heat out as well. No idea why amp manufacturers don't do this. At least none that I've seen

[@auburnamplifiers1786]

You're quite right that thermal design is far from ideal in most mass-produced amps. Mounting tubes on circuit boards gained a bad reputation because it's so poorly done in most cases. But if tubes are upright and boards have ample copper and ventilation holes, and if the enclosure is well designed and made from thermally conductive materials, tube life and overall reliability improve significantly. We do these things in our Solitaire three-tube DI for example, which doesn't need a fan to achieve excellent ventilation. The same approach works for higher powered amps as well. Designers at most amp manufacturers aren't ignorant; they're just bowing to market pressure to build amps to specific price points and with conventional layouts, even if these are inherently flawed. But there are always manufacturers like us at the fringe who are free to creatively focus on engineering, design and build quality. We're not interested in manufacturing thousands of amps. We feel it's more important to provide instruments that deliver the goods flawlessly and conveniently year after year without ever needing mods or kid gloves.

[@777bigbird]

In your opinion sir , what do you think the actual cost of parts to construct a 50 watt rms tube amp would be ? What tubes would you use and what design would be the easiest / simplest and less likely to have problems ? Was Hartley PEAVEY on the right track with his earlier classic series ?

[@auburnamplifiers1786]

Hi, Ben. Thanks for your question. There's no one answer unfortunately, as it all comes down to what features you'd want and how resourceful and skilled you are. You can go a long way in building an one-off musical instrument amp cost effectively if you can repurpose an existing chassis and/or transformers. If you'll be buying output tubes, check the prices of the various types before making your final choice; their costs range considerably and will have an impact on your project cost. An isolation transformer with a voltage doubler can often make an acceptable plate supply, and a 12V LED power supply can serve as filament supply. Some hobbyists can put an amp together from things they have lying around, which can be a fun challenge. Repairing a non-functional used amp can be an affordable solution. Kits aren't as cheap as they used to be, but they can also be good value. The important thing to keep in mind is that tube amplifier voltages can injure or even kill you, so it's best for you and your family if you don't tackle anything beyond your skill and knowledge level. Re the early Peavey Classics: yes, good amps, good platform, and a respectable alternative to the usual suspects. Good luck with your quest!

[@hootowl6354]

Well done, sir. I can't tell you how many times I've heard the term 'point-to-point' misused. Even amplifier companies do.

[@auburnamplifiers1786]

True! It's equally frustrating to hear established manufacturers talk about folklore like "EL84 chime". No wonder guitarists get confused.

[@Visceri_CSKTS]

Thanks for the video! Well-presented. The true point-to-point stuff made me queasy!

[@auburnamplifiers1786]

You're very welcome. It's a curious thing that the chaos inherent in what are often the most efficient systems - whether in amplifiers or in nature - makes humans queasy.

[@jonathanj-g-yyelle6144]

Thank you for taking the time, and effort, to explain this to us. Happy New Year to all of you and good health.

[@auburnamplifiers1786]

Thanks and Happy New Year to you too!

[@ruthbroadway3157]

Thanks for the videos Rob. As i'm getting more into the repair world these are very helpful!

[@YoureNowOnTV]

I know more now than I did before I watched this video. Thanks ! 😀👍

[@italianbirdvideos6190]

Thank you. Very interesting.

[@giulioluzzardi7632]

Thank-you for that "Clear" and "Concise" description of the board terminology and thier differences. BTW , what is the amp at the start on the video Still? Looks very well put together and designed. HIWATT 100 IN THE PIC?

[@auburnamplifiers1786]

Thanks very much for your positive comments. Yes - that's a Hiwatt.

[@NullStaticVoid]

Always wondered if turret board was related to wire wrap construction. It seems like it would be good for that. Maybe prototype on wire wrap, then solder down when its good?

[@auburnamplifiers1786]

The wire-wrap I'm familiar with is an entirely different animal, and was commonly used for prototyping early digital circuits based on DIP packages (e.g. TTL). I don't think I've never seen this kind of wire-wrap used for analog circuits. It did sometimes find it way into finished one-off and very low production products, sometimes after being soldered just as you describe. But it was kind of a mess to troubleshoot, and stray capacitance was a problem (although it could actually be beneficial in many audio circuits).

[@brendanwalsh108]

Hi Rob, thanks for this which I found very interesting. I wish I'd hung on to my Marshall and Hi Watt amps from the seventies. They just did a job as far as I was concerned back then and I never once looked inside. Happy new year.

[@auburnamplifiers1786]

You're welcome. It's a good sign that you never had to look inside your old amps. You can still get that level of build quality and reliability these days, but generally not from the better-known brands. A happy and successful new year to you as well!

[@Riverdeepnwide]

Great to hear from you again Rob, thanks! 👍🏻

[@mikecamps7226]

I'm glad that you created this production and the photo's of the past. I grew up in a Home Appliance Store as the family business....RCA. SO I really appreciate the nostalgia......in the infancy of electronics......all new uncharted territory....and design ! SO creation of devices that never existed before....operating conditions and environmental aspects applied on top of that....and material science. Wrestling the nature of the beast. Caveman discovering FIRE was pivotal, and electronics is still FIRE as for HEAT. They had to maintain a seal for the vacuum aspect and the glass to metal as the pass through and the material science of expansion & contraction with due considerations of the whole as a mechanism. I'm sure today there would be a polymer solution as an enhancement. BUT HEAT is exceptionally vital in the equation, and specially when the components are subject to drift due to heat and aside from the material science.....and if the unit is designed as a HEAT TRAP. So its a point of something being stabile as per the math and on the paper and applying that to real world and all the factors in the operating conditions as with carbon composition of yesteryear as being what was available and that it drifts UP in value with exposure to heat....not factoring the internal heat created by movement of electrons, so what is on the paper starts going sideways in the practical aspect and application. You touched on...CROSS TALK, but should expand that and radiational fields generated with "things" being energized and the physical relationship to each other.....because it all varies between the construction methods...whether it be the ancient birdsnest point to point method....which carried with it the premise that its the Ends of the Leads and the connection is where that component "technically ends", and a "wire" factor starts should a wire be involved....or another direct connection to a component. The Lead out of the body of the component is not counted as "wire"....by convention, but then there was no standard for lead length. (you trimmed to fit relative to component placement). Cross talk and oscillation due to material science & function, and layout design.......and as a consumer good it becomes the manufacturing assembly line & mass production.....without mistakes when everything had the human element involved.....AND not talking about designed obsolescence

[@auburnamplifiers1786]

Fascinating perspective! Thanks very much, Mike.

[@bradleystereoguitaramplifi9616]

Those photographs of the early manufacturing facilities are fascinating.

[@auburnamplifiers1786]

So true. It's worth noting that some contemporary large manufacturing facilities are not fundamentally different.

[@Rodedog55]

Thank you for your video and the educational content you're sharing here. I'm interested in learning much about these amplifiers and need all the help I can acquire. Much Appreciated ! Cheerio !

[@auburnamplifiers1786]

Much obliged, and good for you for undertaking your mission. It's more work, but sticking to established info sources with the occasional scary formula and graph will help you steer clear of hearsay and balderdash. Good luck on your knowledge quest!

[@DrHarryT]

I have a Soundcraftsman PM860 Professional mosfet amp which has a 50V per micro second slew rate. It has zero noise and is clean and crisp when combined with EV musical instrument loudspeakers.

[@qddk9545]

And what has that to do with this video ?? I have an electronic tooth brush with turbo speed.

[@DrHarryT]

​@@qddk9545 It has to do wit the face that the technology of todays solid state amps meet or exceed the capabilities of yesterdays tube amps.

[@qddk9545]

@@DrHarryT They don´t 🙂

[@erikaharrison5357]

Ｐ𝐫Ｏ𝕞Ｏ𝓢ｍ

[@fiddlix]

Excellent overview of tube amp manufacturing technology. Some manufacturers (hint F) just never seem to learn 🤦‍♂️.

[@auburnamplifiers1786]

Thanks very much, David. I'll try to post more videos when I get a chance.

[@robertjamesrobson2907]

@Syd McCreath Interesting! I hadn't heard that before! Thanks!

[@brentstewart59]

​@sydmccreath4554HIWATT amps are just an absolute thing of beauty. Mil spec construction is just simply a class above and to this day nothing else really compares

[@smeh3929]

@@brentstewart59 Підтверджую! Гітарні підсилювачі HIWATT: це еталон якості за всю історію виготовлення підсилювачів у всьому Світі. По будові в середині вони найкращі 👍🙂 У майстернях в руки інженерів для ремонту музиканти приносять дуже рідко. Надійні!

[@ZombieLincoln666]

You look like David Bowie

[@auburnamplifiers1786]

Maybe I should consider a career change :)

[@hywel4605]

if you take the componants off the mother board you get a better sound; mother boards you sending the signal through a led track. i tried on hi fi speaker crossovers and was blown by the improvement

[@iansmith9554]

It is very pleasant to listen to someone with a good vocabulary, and the ability to cogently structure each sentence into an excellent extemporaneous lecture.

[@auburnamplifiers1786]

Thanks very much for your kind comment, Ian. I'll happily accept 'extemporaneous' as a euphemism for 'completely devoid of planning' :)

[@rjlchristie]

Arghh, it's "solder" not "sodder".

[@auburnamplifiers1786]

Like many words in English, it's pronounced differently in different regions. Both pronunciations are correct. Dictionaries can confirm this.

[@rjlchristie]

@@auburnamplifiers1786 Only considered considered correct amongst "American English" speakers. But anyway, what is it with dropping the "l'? You yanks have no problem with words like soldier which also has a d following an "l". Sorry to rant but recently lazy US pronunciation has been driving me up the wall. For example one can;t seem to get away from hearing "twenty" turned into tweeny and from the loss of the "t' from just about everywhere it appears after an "n". So we get the best inner-views from tweeny-twenny-three about inner-nashnul events other inner-resting topics etc. I've got another century of having tweeny rubbed in my face every time I hear a date. Antarctica is another word that consistently defeats you. Eeyore.

[@auburnamplifiers1786]

@@rjlchristie I guess you can be grateful that international English pronunciation is among your biggest bugbears. :) I am not American; I am from a different former colony, all of which have developed their individual dialects. Even within a single nation, pronunciations and even meanings shift over time. This is the nature of language, and is one of the aspects of English in particular that has aided its uptake as what is now essentially a near-global creole. Learning to roll with the changes - in anything - will help keep you positive and focused on more crucial matters.

[@volkspanzer831]

It's like you limeys saying "aluminum" as al-u-menium. Relax, things are pronounced differently sometimes.

[@rogerleelewis3621]

To quote a very wise man (me) “If that’s the worst thing that happens to me, I’ve had a pretty good day.”

[@danamarcy5414]

Thanks I learned allot. VE6KBI