What is nicest sounding 1watt amp config of the many types/tube setups?

[jibberish]

Sanity once again has grabbed hold and I believe i want to build a tiny amp first.    Less parts, less to go wrong deal. also, it will be good for just getting the feel of tube stuff.

So i'm just fishing for opinions, as preliminary looking at circuits indicates there are quite a few different configurations that work.  Maybe some have serious disadvantages or just dont sound nice or w/e

i also have a hammond from the 60's that has what sure looks like 2 different power amps in it..so i need to do some homework and see if maybe i have something that i can mimic or swipe even.

thx in advance.

[Hemisaurus]

You want absolute simple and cheap? Look at space charge tubes? They were designed for use in cars, run from 12V, won't kill you, and you can use like a $3 radio shack transformer for output, if memory serves.

[jibberish]

you know, how when you look at all thes little 1watt heads or combos or schematics, they use different amp circuits and different tubes. i was just wondering if one type typically has a nicer sound than others.  just looking for a direction to choose a circuit.

just cheap isnt the deal.  i want to get the feel of it too, but i'd rather go for something that isnt a documented dud

[Hemisaurus]

http://diy-fever.com/amps/pearly/

Not the link I was thinking of but similar, I think it was a 12K5 and a 12U7, but you could use a 12AU7 if you want.

It wasn't just cheap, there's a big safety factor if you are only playing with 12V, and why bother with high plate voltages on a small amp. Plus they are proer sized, makes them easy to work with, and get sockets for. Google things like sopht amp and space charge.

[dunwichamps]

I have done this before. I built a ~1W power amp with an ECC99 output tube and the preamp was kind of like a rodded Orange OR minus the cathodyne as the output stage was self split

http://dunwichamps.com/ECC99_Combo_Amp.html

Easy to do, and u can do it with leftover parts. Transformers are not a huge requirement as there is very little power in the amp


I gutted a 1x8" combo amp as the shell and used a hammond chassis and tranny, 2 12ax7 pre tubes 1 ecc99 output. bax stack voume and master


Self split output stages are simpler and less efficient as compared to using a long tail pair phase inverter. It all depends on how complex you want to the circuit to be. A traditional design would use a LTPI. An ecc99 is a really nice bigger triode which has a much higher voltage swing than a 12au7 or 12ax7. You could build a nice amp to rip on with just 2 preamp tubes and a ECC99. Wont be a gain banger but it would be good for a small apartment.

I can post a schematic for u

[Hemisaurus]

Found this, the guy even has a schematic, low power, low voltage tube amp.

The nice thing about low voltage construction is you can use regular caps, an old 12V wall wart, you can get pretty much everything you need at the shack, except the tubes and sockets.

[jibberish]

a) thanks tons for putting your time into this.  i actually am able to, and AM appreciating these ideas and info.

ok, so there is no b....nm

Anyway..
this low voltage amp idea is something i should do, just to do it, for sure.  ya i'm a TTL lover, so no problems there.
and yes, talk about handy-dandy, no worry safety, and inexpensiveness.  no arguments here.

I also really really have some insane ideas regarding standard amps. that OR-120 looks like a righteous final goal. BUT,i only learned transistor amp theory, so as such, i at least know wtf an amp really is, but not much more with the tube technology.
SO the tube voodoo is its own black art with its own lingo, specs, tests, yada yada. and fun voltages heh.

So i actually was thinking more of the overall materials experimenting i want to do.. if i have to mess up a piece of resin or something, id rather have only drilled w/e 20 holes and not 120, and used only 1/4 the size of material for w/e. i want to do some noise studies , horsing around with shielding, etc etc ETC.... so all of that is much less resource waste while designing if im using a small  size/component count circuit but still is akin to any loaded up one of higher power.(in a past life i was a product mgr of a control electronics line..i was the final say a-z. you will see things after 10 years of dealing with the engineering dept. and not just my shit, they had many projects..great exposure to materials/techniques. see a ton more onsite at customer installs or potential sales sites) went to half a dozen trade shows every year, worked most of them too. talk about seeing some shit. i saw some shit.

im explaining this to stop if there is any "wtf is with this guy" deal. i have a crazy different perspective, and you'll see my thought patterns and nature of questions tend to reflect that a bit. and you never know, with me slinging mud, something from my industrial control world MIGHT be super when implemented into the music world..i have no idea, just have to play it out and see what happens.

this whole thing really started years ago looking over red giant's marshall heads a few times. i thought even then, utilitarian on the inside for sure. then i start seeing some amps where the builder took a bit of resources and parlayed them into some aesthetics. sexy IS sexy. i love the music, i want to build thee sexiest righteous sounding amp ever. or have a total blast trying

[Hemisaurus]

A tube is a high voltage, low current transistor. Now you know all about tubes, a triode is very similar to a regular transistor, even more similar to a FET, if you learned about those? The extra grids in a pentode are there for electron control and usually have a set voltage on them, the screen isolates the control grid (think base) from the high voltage on the plate (think collector) and also helps the electron flow once the tube is on, it's generally held at high voltage, but lower than the plate obviously. The suppressor grid is generally grounded or connected to the cathode (emitter) and is there to catch stray electrons from the plate.

Theres no reason you can't make a full tone stack amp from space charge tubes, the main difference between a 12(A)U7 and 12AX7 is the gain 13dB vs 20dB. You can also connect power tubes in parallel for more power, without needing to have a push pull transformer and phase splitter.

Weber have a flea output transformer, that does 3W and has 4K and 1.5K primaries and 4 and 8 ohm secondary taps, it's suitable for high voltage tube stuff as well.

Because I'm mentioning space charge tubes as an option, theres also regular HV tubes as well, some 12AX7's and a small pentode, EL84 or 6V6 or 12BK5 or so.

[Chovie D]

Sanity once again has grabbed hold and I believe i want to build a tiny amp first.    Less parts, less to go wrong deal. also, it will be good for just getting the feel of tube stuff.

So i'm just fishing for opinions, as preliminary looking at circuits indicates there are quite a few different configurations that work.  Maybe some have serious disadvantages or just dont sound nice or w/e

i also have a hammond from the 60's that has what sure looks like 2 different power amps in it..so i need to do some homework and see if maybe i have something that i can mimic or swipe even.

thx in advance.

would a 1 watt tiny amp be simpler to build than say a tweed champ?
My buddy made a reaslly  nice 18watt clone out of hammond chassis and trannies i think

[dunwichamps]

Yes easier to build than your run of the mill 5e3 tweed.

Although i believe an 18W (2 x 6v6 or 2 x EL84) amp is fairly easy to build when you look at the bigger picture of amp building. I know of a lot of 1st time builders doing that amp very successfully.

[Hemisaurus]

I think that a simple single-ended (Class A) amp is generally an easier build, just because you don't need to wire up a phase inverter. It's just easier because it's less components, then space charge (low voltage tubes) are even easier because there's no HV supply, if you use a 12V DC wart, you can use that for the heaters and the plates and screen, if you use a 12V AC wart, you can run the heaters from that, rectify it to what, say 18-20V DC for the plates, and drop it down for the screen grids.

You can simplify a 5F1 circuit, by using a silicon rectifier, which cuts it down to two tubes, and as you don't need a 5V heater for the rectifier, that can broaden your power transformer choices. I think having one double triode 12A(?)7 and a single power tube, is an easy build, if you need more power you can use an EL34 or 6L6 or 6550, there are some nice single ended 15-25W output transformers available in the $30 range.

I have an all tube preamp sketched out, which has a single switchable 6550 power section, so that it can function on it's own as a small amp, but you can turn the power section off to just use the preamp. Another one on the when I have time stack. I really designed it purely as a preamp, and then thought, well I can just add in a power tube, and an output transformer, and have a whole amp.

[dunwichamps]

You can use a self split output stage to avoid a phase inverter

check here

http://ax84.com/media/ax84_m276.gif

There some flea amp based PT, and OT sets, any old reverb driver can be used as an output transformer because they are used in Fender reverb circuits driven off 12at7s.

I think you can do a HV B+, even tho its definitely more dangerous, potentially fatal

[Hemisaurus]

You can just parallel up tubes on an SE transformer as well, most SE xfmrs don't have a center tap and a PP xfmr won't do single ended at any power.

[jibberish]

this is some rich shit. thank you..oh boy like christmas.   you guys are one helluva knowledge pool.  and i know, the best way to learn voodoo shit is to have experience with it. 

and ya, i think to just say "i whooped it together and it makes noise" i'm going to start the shopping list for the low voltage stuff. 

chovie, i keep looking at some of this stuff...these little amps have like no component count.
i keep coming to the same conclusion:
" i HAVE to be able to cook something up fairly easily looking at the 1 watt amp circuits "
so i'm gonna do it.   i will post progress too as i win or fuck up or hit the wall. 

i have a ton of research and other homework to do now.
if some kind of regulated dc is needed, i like powerblocks, i would use SS for non-tone affecting crap like rectifiers, clamps, buck-boost w/e. stable bias voltages or w/e no problem

and i know 1st iteration will be just the clean amp essentials so i can "feel" the tube and what it does through its operational range. y'all have a HUGE advantage, those who have spent mega hours playing thru a tube amp, you have a feel. so i think i really need to listen to a tone of a lot of tube amps now too.  with no vector you are a ship with one oar in the water.  you can tell :"whats a good circuit to try first" is a total "help me get a direction" plea.

Fuckin' A! got some direction now
[throws a big thumbs-up]

[dunwichamps]

a lot of shit can be learned by reading through ValveWizards shit

I have both his book, great for builders with some experience but please read his first Ch1, its available for free

http://www.freewebs.com/valvewizard1/Common_Gain_Stage.pdf

Goes over basic operation of a Class A preamp stage, biasing, load lines. Perfect stuff whether you use a low voltage or high voltage setup.

Also plenty more on his site
http://www.freewebs.com/valvewizard/

[Hemisaurus]

Hey Dunwich, whats a nice cheap little power transformer to couple with the Weber flea OP xfmr, if you were looking at using normal triodes and a small power pentode?

[dunwichamps]

Hey Dunwich, whats a nice cheap little power transformer to couple with the Weber flea OP xfmr, if you were looking at using normal triodes and a small power pentode?

which power pentode a 6v6 or EL84? or something I do not know about Dont know if Webers OT can handle a 6v6 or EL84 your more likely use a 125 series hammond.

I used a Hammond 269Jx last time I built a flea amp with a ECC99.

500V C.T. @ 69ma
6.3V @ 2.5A

43 bucks at CEDist
42 bucks at Angela

If you dont need that kind of power

269EX is 40 bucks @ Angela

Antek has a 120V tranny for 25 bucks with a double you could get a good voltage

AN-05T120

Heres a 40V secondary with a double that you could get fairly low voltages but still nice,

11 bucks

AN-0240

[Hemisaurus]

Hmm, yes to the first Antek, it's like an isolation tranny with a heater, no to the second, no heater 

I need to crack their code, here's one for $25 two heaters a 320V and 300V 50VA AN05T320

[dunwichamps]

Hmm, yes to the first Antek, it's like an isolation tranny with a heater, no to the second, no heater  

I need to crack their code, here's one for $25 two heaters a 320V and 300V 50VA AN05T320

all their stuff has no center taps so you have to use bridge rectos to get what you want

The heater lines have no CTs but no biggie just make a artificial center tap with 2 resistors

Spec sheet on tranny i first suggested

http://www.antekinc.com/pdf/AS-05T120.pdf

watch your size on that tranny its

3.4" in diameter and 1.6" in height

[Hemisaurus]

I do like toroids Remember I pasted that Plitron 400W output behemoth?

Eight KT-88's, I'd need to remortgage the house every retube

[dunwichamps]

I do like toroids Remember I pasted that Plitron 400W output behemoth?

Eight KT-88's, I'd need to remortgage the house every retube

or whore yourself all night

yea 8 matched 88s is nuts.

They are nice PTs, low noise, and nice profile. Good for this kind of app

[jibberish]

quick question: Does anyone actually manufacture those space charge tubes like how the russians started making HV tubes again.

i'm not too keen on having to rely on luck to get something done like finding parts.

that little sophca u7+k5 amp is a cute little circuit. looks like all standard cap and res values which i should have all of already (maybe not all(if any) that need to be >1 watt<--which may be needed because these tubes are current hogs).

but if even finding the tubes is a crap shoot..i dont know....probably if i cant get satisfaction regarding a constant supply, i'll leave the space charge tube amp alone and continue on to the HV 1 watt circuits. 

[Hemisaurus]

NOS only AFAIK, but tube store or tube depot had 'em last time I checked.

[mawso]

The valvetone impact is the nicest low watt amp i've played.  I think it ends up being 2 watts not 1.  But anyway it's great, and people have built their own versions of them.

I have never played a Hall Amplification Lil' Devil but the clips I've heard nevertheless make me want one.  They sell it as a kit as well as a completed amp I think.

As best I understand it, both of them run 2 power tubes in Class AB, and I like that sound better than a Class A amp.  Most really low watt amps are too "spongey" and not "punchy" sounding enough, if that makes sense.

[jibberish]

thx mawso. that is a key opinion.   

ya, that's all i was finding looking for the 12volt tubes.  old stock.  that means there is a finite amount. cool for screwing around one time to do it, but uselesss for anything further.  and from what reading i did, those 12v amps do not sound better than HV tube amps anyway.

i tell you what, that was HUGE for car radios though vs HV, gotta appreciate that.

50 year old tubes..gotta be a little nervous about that