• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

beginner needs advice!

Old Bob

Member
2019-12-02 5:56 pm
good morning!

I am NOT going to build amps, but I thought this would be a great place to learn about tubes, and, tube amps!

I have a tube integrated amp, and love the sound.

dumb questions:

1. what can I read to learn all about tubes?

2. what do you think of a good tube preamp, connected to a good solid state amp? example: a nice Primaluna tube preamp, and a McIntosh or Pass solid state power amp?

3. I would like to try, slowly, to learn about tube rolling. I would begin with the tube preamp, and ask advice along the way!

I may say I attended a headphone show, and loved the headphones with tube headphone amps, notably Schiit headphone amps1

any and all advice is most welcome.

and THANKS!

best regards,

Bob
 
Hmmm. How deep into learning do you want to go? A great resource would be the lessons here-

http://sportsbil.com/other/Basic%20Electronics,%20Volumes%201-5,%20(1955).pdf

Go through the whole thing if you'd like an excellent, down to earth electronics primer from the good old days, or just dig through the parts you're interested in.

I'm not going to say much on the second question, other than that a preamp is rarely needed or even desirable with most modern amplifiers. Unless you need a phono preamp or similar special case you should have plenty of gain to begin with. A simple source selector with or without volume control would be a fine preamp without any extra gain or powered circuitry.

As for tube rolling, well, I'm of the camp that it will rarely give a large difference in sound but can be an interesting exercise in some circuits without much complexity, or in output stages. Best advice is to absolutely verify that any tube you purchase as an "equivalent" is actually so. Many Chinese and Russian tubes are marketed as such by unscrupulous dealers when they at some times may be wildly different unless modifications or adjustment is made to the item you intend to use them in. For instance- the 6AQ5 has the Russian 6P1P and Chinese 6P1 often sold as replacement "equivalent" tubes, when they use a completely different socket and pinout. Same with the 6N1P/6N1 being marketed as a 6DJ8 equivalent- other than gain as well as pinout they are very different electrically, but can be made to work in many circumstances.
 
2. what do you think of a good tube preamp, connected to a good solid state amp? example: a nice Primaluna tube preamp, and a McIntosh or Pass solid state power amp?
Bob
I've got a tube preamp, a dynakit PAS2, and a solid state amp designed specifically to be driven by a 12AX7 plate, the dynaco ST120.
When one board lost lands in the ST120, I had to do custom modifications to a amp board popular in solid state (AX6) to achieve the 250kohm input resistance necessary for the PAS2. And I'm no designer.
The bottom line is a heavily improved op amp mixer, the Herald RA-88a sounds better than the PAS2 with modern plastic caps. The old paper caps in the PAS2 were causing a weak channel. The mixer uses 1/10 the electricity, and doesn't require new rectifier tube & B+ e cap every 10 years. The mixer does do RIAA MM cartridge, so I can listen to my 3000+ LPs. The PAS2 can only drive 6' RCA cable. I'm using the mixer to drive 12' RCA cables, which fit better in my music room. Yhe PAS2 requires a walk around the table to switch input from LP to CD to FM radio. The mixer allows all to be at destination level at once, so no switching: And no annoying hiss or hum either.
Tubes are better at modifying sound from guitars in a pleasing fashion. Other than that, my solid state stuff like the Peavey CS800s sounds better than the tube dynakit ST70. .03% HD compared to 1% HD, it is quite audible. Yes, $$$$ could make a better sounding tube amp. The CS800s cost only ~$200 used and $50 e-caps to renew for another 20 years.
I've got tubes I still use, the Hammond H100's have 23 each and the A100 has about 12. Hammond tried to solid state convert the H100, the X77 was a hummy mess. I'm glad I can still get good 5AR4, 6BQ5, and 7591. The other tubes don't wear out, only the 199 e-caps.
 
Last edited:
A good way to get into tubes is to look up circuits and get a general idea of topologies and circuit layout and component values.

Tube amp building is fun, either point to point layout or PCB.
I always found pcb easier.
The main thing if you are going to mess with valves is safety, the blighters can bite or kill !
On my designs I always add series resistor and LED from power supply to zero volts so I know when the caps are charged up.
 
hiya Bob.

I started with a really basic cathode follower line buffer. It didn't do a lot (perfect buffer performance really!) but it taught me a lot, had an extremely low parts count, and could be placed between any device (except a turntable) and any amplifier.

That was followed by a trio of 12ax7/el84 se amps - identical, for each of my kids. Taught me a bit more, all built from recycled 60-year old consoles, low parts count, basic design that could be adjusted to see what effect it had etc etc.

Building and committing to the design taught me the practical side of the reading and chatting here.

My advice - choose a simple, basic design and build it to understand it.
 
All those resource links are great.
However, skipping the fundamental "basics" of electronics isn't wise to overlook.
What I'm saying is, in order to really and properly understand about anything electronic, and how it works, you need to first understand basic, and sometimes advanced electronic theory.
AKA "schooling", like I once had to do, decades ago.
This is of course the "rocket science" that lots of people seem to ignore and claim that it isn't - and so they foolishly bumble into things with repeated failures and wonder why things aren't working right.
And how could they? - if they don't know Ohms Laws, or resistor color codes, or the plethora of conditions that capacitors rely on to function?
And as such, dealing with anything electronic is hazardous to the uneducated tinkerer.


Yeah, I get that tired, worn out cry of "it isn't rocket science" crap from people that refuse to believe that my years of professional schooling isn't needed, and it doesn't bother me at all.
But of course, I know better.
You wanna play "technician"? - then go that extra mile like I did, just don't expect anyone like me to label you a valid technician if you only have a soldering iron and a cheap dollar store DVM, because that doesn't make you anything more than a putzer.
LOL!
I said my piece.
 
Schooling and knowledge is required, but it is in no way comparable to rocket science or astrophysics, or even semiconductor quantum mechanics (which is the closest comparison)

But wow, that is what I call "blowing your own trumpet", and what an abhorrent way to discourage a novice to take on the challenge of learning.

Thank goodness for the ignore button.

Sour old tech would be more appropriate
 
And, per KodaBMX, I've also come to conclude that there are very few ways to competently “learn electronics” short of choosing a bunch of simple projects, working thru the (frankly, simple) math, and then breadboarding them.

The mistakes made along the way … apart from sometimes-spectacular … are priceless. You'll never forget fissioning a 2.2 kΩ resistor as a capacitor bleeder at 350 V, when you had intended 220 kΩ, and misread the color-stripe-codes. Not a blam, but a snap-fizzzit. And smoke.

Same goes for hooking electrolytic capacitors into circuit … backwards polarity. Smoke.

Same goes for doing um, improvidential things … with vacuum rectifiers.

But, the lessons are priceless.
So long as one's personality isn't to repeat mistakes, mistakes teach.

Start small.
Work with low voltages to begin with.
Ramp up as your experiences … warrant.

Just Saying,
GoatGuy ✓
 
For the record, I've met many "educated" people who were just plain stupid... Education != intellect.

the smartest folks I know are complete morons, if you know what I mean.

And, per KodaBMX, I've also come to conclude that there are very few ways to competently “learn electronics” short of choosing a bunch of simple projects, working thru the (frankly, simple) math, and then breadboarding them.

The mistakes made along the way … apart from sometimes-spectacular … are priceless. You'll never forget fissioning a 2.2 kΩ resistor as a capacitor bleeder at 350 V, when you had intended 220 kΩ, and misread the color-stripe-codes. Not a blam, but a snap-fizzzit. And smoke.

Same goes for hooking electrolytic capacitors into circuit … backwards polarity. Smoke.

Same goes for doing um, improvidential things … with vacuum rectifiers.

But, the lessons are priceless.
So long as one's personality isn't to repeat mistakes, mistakes teach.

Start small.
Work with low voltages to begin with.
Ramp up as your experiences … warrant.

Just Saying,
GoatGuy ✓

Hooking up a 63 volt, 33,000uF electrolytic capacitor backwards is an experience that everyone should experience at least once :)
 
Schooling and knowledge is required, but it is in no way comparable to rocket science or astrophysics, or even semiconductor quantum mechanics (which is the closest comparison)

But wow, that is what I call "blowing your own trumpet", and what an abhorrent way to discourage a novice to take on the challenge of learning.

Thank goodness for the ignore button.

Sour old tech would be more appropriate


^^^^^ I'm used to these types of comebacks to my comments. ^^^^^


And it's not "discouragement" as I'm accused of, it's simply stating in clear yet serious terms the time-tested and proper series of requirements that all reputable technicians are required to learn in order to be as successful as possible.
We're dealing with other people's products in our business, we aren't supposed to kludge around with their sometimes expensive equipment.
It's not an option, and making mistakes isn't a laughing matter there, because it costs us money, our reputation, and business.
 

6A3sUMMER

Member
2016-06-07 6:50 am
1. If you like to read hard copy instead of your computer screen, see if your local library has a copy of "The ARRL Radio Amateur's Handbook".
If they have an old copy from the 1950s, so much the better, more tube theory and tube projects. But any year version will teach basic electronics.
You can also order a current hard copy online from the ARRL.

2. For those of you who remember Bob Pease, he had a question from an engineering student who wanted to become an analog engineer. If I correctly remember Bob's answer, he said something like: have you been tinkering with circuits, building, designing, etc. Without that, you will have a hard time becoming an analog engineer.
 
Any amateur doing a professional’s occupation is a potential liability since we do just do not have the safety aspects ingrained deeply enough. Hence I do not have the tip of one finger, and had an unpleasant experience picking up a guitar amp with no base plate. (No power, but no fuses or tubes, so power supply capacitors were still charged)

I understand where Wiseoldtech is coming from. At some point you need a grounding (sic) so you are able to predict what is going on with the mixture of AC and DC, and active and passive components.