It's time for some tube amp questions !

[seadi123]

I've never worked with tubes , but they seem a LOT easier to work with , instead of "microscopic" transistors and op-amps . Especially 8 pin op-amps , they are like nightmares ! Are tube amps easier to build ? And also what are the parts that cost more on tube amps besides hardware (chassis , enclosure , speaker ...) ? 1 tube usually cost 15$-25$ , how comes transformers cost so much more Are there any alternatives to transformers ?

Also 1 last question . Lets say i use 1 tube for the preamp stage , can i use a op-amp for the power stage ? Like the TDA2040 ? It would run on 9v and there would not be need for transformers . It would not be an all tube amp tho , but a solid state .

Can someone tell the cheapest way to build an all tube amp ? 1 tube preamp + 1 tube poweramp , transformers ?

[StarGeezers]

 Sead...  I'd suggest you go here www.wattkins.com  .. all your tube amp  questions will be cheerfully answered...  

[GibsonGM]

Hi!  Well, yeah, I thought a lot of the same, 'way back when', ha ha.   I still like to mess with tubes - they sound Awesome - but are NOT easier to work with than BJTs, FETs etc.    They are much harder!   :oO     My opinion, YMMV.   It is slower, too, again my opinion...you have to work slowly and smart when you're in there...

Why harder?  Because you have to REALLY design with tubes...you have to start at the power supply and do a lot of gymnastics to come up with the correct voltages (HIGH voltages, most often) for your circuit.   You need to run the heaters, which draw a lot of current, thereby messing up your carefully-laid plans, lol.  You don't just pop in a 9v battery.   It's not TONS more difficult, but you may find that you need a lot more stuff (and a lot more knowledge) than you thought, as opposed to just going to the junk box and pulling out a few resistors, caps and transistors to make a nice circuit for yourself.  If you burn something with tubes, it is gone forever - not just a 50 cent chip.  Toast that OT, and you just spent $80, you know?   BJT stuff seems more....intuitive...to me.  

You have a lot of 'power problems' with tubes....you need to put the heat SOMEWHERE....this means getting power resistors, expensive caps to deal with the voltages, etc.   NOT a good way to start out, IMO....after you really dig into transistors/opamps and stuff, THEN you may wish to carry on into tubes.   FETs sound amazingly tube-like, you know!  I'm not discounting lower voltage circuits, but really - don't you want to build a classic amp that was on the market??      

Transformers cost $ because they are big iron and a lot of copper wire, labor-intensive and few people need them anymore - so there ya go, market value.  Alternative - SMPS, switching power supply like a Nixie supply, but that doesn't get you as high a voltage, and may require some tweeking to get right.   A few circuits work ok at lower "starved plate" voltages (search on here), and there ARE sub-mini tubes that run at 12V (car radio tubes....).    Those are good to play with, to just get a 'sense' of what is going on, and are safe to learn on.  But may leave you wanting "more", IMO.  They are mostly overdrive, not the sound of a JCM800.  

You CAN use an opamp for an output stage, or a traditional transistor output....many feel you are losing the warmth of the tubes, tho, which is the entire reason you built it in the first place!  Research "preamp vs. power tube distortion".    May be better to use FETs.....1 tube won't get you much in the way of distortion, by the way.   Good "modern" stuff takes over 4 stages, speaking generally. More like 6.  Classic rock, more like 3-4, meaning 2 dual triodes like the 12A*7 series.  

After you build for a while, I'd suggest doing some research and getting a kit for a Marshall 18W!  Build that sucker up, you have directions, and it's hard to mess up.   You get a GREAT, REAL tube amp (I mean, $400 kit gets you a $1200 amp!), real power tube distortion (!!), and you can mod the thing to your heart's content - which gets you in the door, gets you comfortable working with the voltages and techniques that are unique to tubes.  

Don't get me wrong, I LOVE tubes, tube sound, and designing odd, freaky and cool stuff, ha ha.  BUT....May sound weird, but I feel it's better to work backwards from the 70s pedals like Dist + and move back into tubes after you really have a handle on things.  There is a reason they left tubes and introduced these other devices.   Just my thoughts on it!    Check out Merlin's site, he has TONS of info to review, and is on here to ask questions of....

http://www.valvewizard.co.uk/  

[seadi123]

Thank you very much GibsonGM I guess i'll have to go back to my tiny stuff and hope to not lose my patience . I still haven't found a non-tube amp that sounds GOOD . Maybe after some time i will build the 18w marshall , or a tweed 5f1 , since im not looking for too much gain . Thank you very much for the sub-mini tube amp suggestion , they look realy interesting Cheers

[PRR]

> can i use a op-amp for the power stage ? Like the TDA2040 ? It would run on 9v and there would not be need for transformers

It will "run" on 9V but output "power" will be 1 Watt. It really wants _dual_ 16V supplies (for 12W-18W).

So now you need 6V for tube heaters, +/-16V for power stage, and 250V for tube plates (there's butt-loads of difference 250V versus 16V on a tube stage). THREE (really four) power supplies! All with the transformers you dislike.

I suppose a hefty One-Spot or similar could feed a few heaters (via dropping resistors) and a one-watt chip. But not the tube plates, not in any way "similar" to the Classic Tube Sound got with 250V.

> the cheapest way to build an all tube amp ?

You want to listen to a *cheap* tube amp?

If you can't stand the heat, stay out of the kitchen.

OR decide you WILL spend whatever it takes to Do It Well.

The cheapest way is to BUY a Epi Valve Jr and hack it up. Asian mass-marketers can sell the whole amplifier much cheaper than you can buy parts. I spent around $480 to build a 13-Watt super-Champ; the Jr is a 6-Watt Champ-clone for $99 at your nearest Banjo World. The power transformer is very adequate. The OT is not as bad as a lot of the stuff we bought in the 1960s. The speaker... well, it speaks, but a better (bigger!) air-slapper is always wise. The EL84 (instead of 6V6) is a matter of taste. And the Jr's circuit is made to not show-up their $199 DeLuxe clone... rip it out and do it as an AA-Champ with a nice Twelve, it'll sing. Jr for $99, essential parts just over $100, decent speaker just under $100, you come out at $300 with a unique true-tube amp.

[teemuk]

And at that price you can probably buy a very good but used tube amp. Last time I remember discussing something involving using cheap amps as modification platforms I checked ebay and a mint Peavey Classic 30 was auctioning for about 300 bucks. That put a quick stop to my urges to purchase a $#%¤ Valve Junior and spend $200 extra to mods that merely make it "ok". Not great or even good. Just "ok".

...But this is DIY so enough of that. But "cheap" isn't usually very fitting name for this hobby, especially when it starts to involve the ancient tube technology.

[seadi123]

@PRR I would not need 18w output , so i could use a SMPS to power the tubes and the op-amps with 12V . I know it would not sound like a tube amp , i'm not even trying to get SO close , but i'm pretty sure it would sound WAY better then 1W ic-based amps !

@teemuk i know buying used amps is great , but i live in Albania (EU) , and there is no way anyone is shipping here .

Now i know the word "cheap" maybe pisses you , but the point is i live in a 3rd world country . I have to find cheap alternatives to almost anything . I have even built my own guitar ! So , CHEAP is very important around here

BTW here is a picture of the queen