| Time to rock your world. - Click HERE for Original Thread |
| Sch3mat1c |
Enough pussyfooting around with these wimpy 300B SE "amps". Try this motha on for size!
:bigeyes:
Power supply is here:
- There are a few bugs (I think) that have to be ironed out. Try to spot them :) (There's plenty of time for that while I rewind the MOTs..)
Tim |
|
|
| halojoy |
Those Trafos will NOT, NOT be low priced,
if I ever get to find them ...
so I stay Happily Solid Discrete
like most people of the world
when it comes to POWER amps
Happy building, Sch3mat1c
You will be one of a few ;) (lucky?)
/halo - main stream artist ... :cool: ;) :cool: and Happy |
|
|
| Sch3mat1c |
Actually, I only intend to spend maybe $100 total...
[Dramatic pause while everyone passes out]
Only iron I'm going to buy is the filament trannies..the HV PT and OPT I'll wind on Microwave Oven Transformer cores.
*=- All Hail The Mighty Junk Pile -=* :D
Tim |
|
|
| 7N7 |
| quote: | Originally posted by Sch3mat1c
Actually, I only intend to spend maybe $100 total...
[Dramatic pause while everyone passes out]
Only iron I'm going to buy is the filament trannies..the HV PT and OPT I'll wind on Microwave Oven Transformer cores.
*=- All Hail The Mighty Junk Pile -=* :D
Tim |
An excellent approach.
I have long thought that 6146 has been overlooked; I have a few that I was going to use in a 40W guitar amp; I have all the parts I need, except time.
[And yes I know that Ampeg used them in the early SVT]
Keep us posted
7N7 |
|
|
| halojoy |
| quote: | Originally posted by Sch3mat1c
Actually, I only intend to spend maybe $100 total...
Only iron I'm going to buy is the filament trannies..the HV PT and OPT I'll wind on Microwave Oven Transformer cores.
*=- All Hail The Mighty Junk Pile -=* :D
Tim |
I am sorry.
I had no idea, you can build a TUBE power amp
of that kind - with low money. :cool:
This is what happens, when I speak of things
I only "think I know"
but do NOT, in fact, know so much about.
Good Luck with an interesting TUBE project
Sch3mat1c :)
/halo - have to learn more :rolleyes: |
|
|
| dhaen |
| quote: | | I had no idea, you can build a TUBE power amp of that kind - with low money |
So, Halojoy, no excuses at all for you now;)
Go....get'it:nod:
Cheers, |
|
|
| miguel2 |
| I tried a 6L6GC (new) as pass tube in my preamp PSU but the only thing I got was a blue flash inside it, along with some noise (tik). Replaced with an old EL34 and it went ok. I am also using a zener (man this one was hard!!) instead of the 0B2. Anyway, that thing is not perfect, as I need 1000uF to get rid of the hum after retification (around 180V). |
|
|
| Sch3mat1c |
I'm not going to worry about the 6L6. They're used all the time in guitar amps at 500V, meaning peak plate voltage is up to 1kV (much more if it does a flyback pulse somehow), and they manage to last a few gigs apparently... :)
(And besides, I'm gonna use my pair of EL34 in something else :cool: )
1000uF eh? Sounds like you must've had either ground loop or you forgot your PS choke...
Tim |
|
|
| miguel2 |
| Hehe. No PSU choke indeed. Those things cost money and I could not find one in the junk store. Anyway how can a choke be differentiated from a transformer (I mean in a big pile of junk)? Number of wires coming from it - 2 instead of >4? |
|
|
| slowmotion |
Hi Sch3mat1c,
| quote: | | Only iron I'm going to buy is the filament trannies..the HV PT and OPT I'll wind on Microwave Oven Transformer cores. |
Hrrmm.... tell more, please?
I have cores, I can get wire,
but what about insulation?
What do you use so nobody get zapped? :dead:
Or is that a new thread?
:) |
|
|
| choky |
***Jan Rowland, Roll Your Own Power Transformers:
http://members.tripod.com/~schemati...rm/xformer1.htm
***Patrick Turner, Output Transformer Design Calculations:
http://www.turneraudio.com.au/htmlw...designcalcs.htm
*******ransformer Basics, from Lessons in Electric Circuits:
http://www.ibiblio.org/obp/electric...ts/AC/AC_9.html
***Determining OP Transformer Impedance:
http://www.geocities.com/vintage_radio/outimp.htm
***Basics of Inductors:
http://www.hills2.u-net.com/electron/induct.htm
* VoltSecond and Mike Lefevre, What does the Transformer Inductance do
to the Loadline of the Tube?
http://www.siteswithstyle.com/volts..._LOAD_LINE.html
✔Gabe Velez, Transformers:
http://members.tripod.com/~gabevee/transform.html
* Michael LaFevre, Transformers and Phase Shift:
http://www.magnequest.com/tech2.htm
* Color codes (MarVac Electronics):
http://www.marvac.com/funpages/chokes.htm
* University of Surrey, Producing Wound Components
http://www.ee.surrey.ac.uk/Workshop/advice/coils/#turn
* David Berning, An Audio Amplifier Design Philosophy:
http://www.meta-gizmo.com/Tri/otlology/BERNINGS.htm
✔Randall Aiken, OPT's Explained
http://www.aikenamps.com/OutputTransformers.html
* Richard Sears, Trany Math:
http://richard984.tripod.com/transformer_math.htm
* Lundahl, Technical Papers from Lundahl: very short pieces from
Lundahl lab: http://www.lundahl.se/papers.html
* Pete Millett, Power Transformers for Audio Equipment:
http://www.pmillett.addr.com/images/ax_power.pdf
* VoltSecond, Damping Ringing in LC Circuits:
http://www.siteswithstyle.com/VoltS...g_in_xfmrs.html
* Plitron Site:http://www.plitron.com/Pages/sitemap.htm. Link takes
you to site index. Under "Publications". A collection of articles
including:
-Secrets of Output Transformers, Menno Van de Veen
-Measuring OPT Performance, Menno Van der Veen
-Theory and Practice Of Widebandwidth Toroidal OPT, Menno Van der Veen
-Modeling Power Tubes and their Interaction with OPT, Menno Van der
Veen
* John Atwood (One Electron), Transformer Measurements:
http://www.one-electron.com/Trans_Tests.html
* Max Robinson, Understanding the Transformer:
http://www.angelfire.com/electronic...ansformers.html
*** Dean P Currier, A Biographical History of Induction Coils:
http://radiantslab.com/quackmed/Deanbio.html
*** Edcor, Transformer Tek Notes:
http://www.edcorusa.com/gadgeteer/tek-notes_xformer.htm
Toroid Corp. of Maryland Tech.Bull. #1 ( Application Notes on
Rectifier Transformers) and #2 (International Line Voltages and
Frequencies): http://www.toroid.com/technica.htm
all that from other fellow RAT
:cool: :cool: |
|
|
| slowmotion |
choky,
Wow,thanks man, that was fast :)
Have one on me :drink: |
|
|
| SY |
Is the 330 ohm value in the diff amp cathode circuit correct? Seems like that won't give you much compliance at the swings you'll need for that stage. Why not a ccs or a bigger resistor to a negative rail? And the return of the vr tube in that same stage seems odd; I would think that the distortion would be lower if you used separate returns directly from each screen to the corresponding cathode using a vr or a zener-type circuit.
You may find that you'll need some compensation in the open loop circuit, since you've got a whole pile of HF rollofs which might make stability marginal; an RC across the plate resistor of the input stage will allow stabilization of the closed loop a bit more easily. You might also find that, especially with home-wound stuff, you've got to put a compensation capacitor across the side of the p-p corresponding to the inner windings of the output transformer.
The 6146 is a damn rugged tube and easy to drive. Good choice. |
|
|
| Sch3mat1c |
Yes, the 330 ohm is correct. It will only drop 10V, but with the high Gm of the 6CL6s, will correct distortions well. Since it is a common-mode part, it will not reduce the gain of the stage, while canceling unbalanced noises. A CCS seems an unnecessary complication, and the 40mA draw on the negative supply would be too much for it as shown.
Hmm, I suppose I could return the 0D3 to the 330 ohm resistor instead. Otherwise, I could indeed return each to its respective cathode, and use RC connection instead. (Really, I just wanted to throw in the 0D3 cuz' it looks cool :cool: ;) )
I'll muck around with stability issues when I build it. I hear it isn't quite a predictable thing to model anyway.
And, of course I'll put a Zobel(?) across the OPT :) I recommend everyone do that...send a 1-10kHz square wave through the amp, and try different Rs and Cs until it looks right. Really helped the oscillographilogical appearance of my 6L6GC SE amp.
Tim |
|
|
| SY |
It's not so much a Zobel, but rather the need to set a dominant pole at a frequency at least a decade lower than the other rolloffs to ensure closed-loop stability. That's why it's easiest to do it at the first stage. And you probably won't need that RC across the output transformer in that event, which is a good thing considering the relative AC currents between the first stage and the output.
20 mils per side on the driver is probably more than you need- the input capacitance of the pentode O/P stage won't be too excessive, and a cathode or source follower would be a better option if you want to drive the O/P stage into grid current. |
|
|
| Sch3mat1c |
Sure, I could use a 12AT7 (as plate follower) for the last stage, and it would work perfectly. But it would look so damn weak! :cool: :devily:
OTOH, maybe I could make an amp with just that - call it The Contrast, use a 6AL5 for bias supply and my RK-836 (ST-16, woot) for power supply (I only have one, so I'm not sure how I'll get around the unbalanced supply...). 12AT7 LTP splitter with 24A in negative-resistance region for CCS (oh yeah, gotta add that to the CCS thread), and maybe a quad of 6AQ5 for output.
Tim |
|
|
| SY |
| Well, for perversity sake, you could parallel 60 12AX7s per phase in the output... |
|
|
| HDTVman |
| quote: | Originally posted by SY
Well, for perversity sake, you could parallel 60 12AX7s per phase in the output... |
But only in northern areas for supplmental electric heat.
Later
Bruce:geezer:
PS that would work for you, wouldn't it Tim. |
|
|
| choky |
| quote: | Originally posted by HDTVman
But only in northern areas for supplmental electric heat.
Later
Bruce:geezer:
PS that would work for you, wouldn't it Tim. |
do not mention tha sort of stuff to Tim-he already do that (not exactly 60 pieces,but near enough).
Tim is admirerer of "strange tube in right position" cult :clown: |
|
|
| EC8010 |
Choky,
I am going to blame you for wrecking my printer by forcing me to print out a number of those excellent transformer references. I've had a quick look, and the University of Surrey reference is a nice introduction, and the Patrick Turner looks very practical.
Thank you. |
|
|
| choky |
| quote: | Originally posted by EC8010
Choky,
I am going to blame you for wrecking my printer by forcing me to print out a number of those excellent transformer references. I've had a quick look, and the University of Surrey reference is a nice introduction, and the Patrick Turner looks very practical.
Thank you. |
hehe PT is our faverite PITA guru at RAT;
for some guru,for some PITA.
I call him-Bro ,sometimes old fart..........
contrary to Tim-he is young fart.
btw I'm glad 'cause your printer :goodbad: |
|
|
| Sch3mat1c |
| quote: | Originally posted by choky
do not mention tha sort of stuff to Tim-he already do that (not exactly 60 pieces,but near enough).
Tim is admirerer of "strange tube in right position" cult :clown: |
Hehehe yep...I'll post Hept'AU7 on this board sooner or later... :devily: :goodbad: :nod: :nod: :D
Tim |
|
|
| dhaen |
Hi,
Now, Patrick Turner is the prime Rodent to attract. (No offence to already attracted Rodents). He fills more server disk space with his answers than most, and IMO it's 99% on target:)
Has anyone mentioned this Forum to him?
Cheers, |
|
|
| Sch3mat1c |
It'd be nice to have him but besides his compu-illiteracy, it'd probably take too much time...
Heck, I find I'm spending too much time already...gee, thanks guys :p :)
Tim |
|
|
| dhaen |
| Yes Tim, addictive isn't it? |
|
|
| Neutron Bob |
Hey, now that you mention it, how does one post to rec.audio.tubes? I am not set up to reply. I've run into quite a few posts that I'd love to respond to, but my news reader bounces them back!
Bob |
|
|
| choky |
| quote: | Originally posted by Neutron Bob
Hey, now that you mention it, how does one post to rec.audio.tubes? I am not set up to reply. I've run into quite a few posts that I'd love to respond to, but my news reader bounces them back!
Bob |
try asking your ISP to make RAT available to you in news account form. |
|
|
| apassgear |
Choky,
Excellent links, thanks, have to study but really hate all the math.
I roll my own using RDH4 as a guide with quite good(?) results.
BTW where do you grt your core material?
Been looking for EI 100 in M6 to wind some line pre OPT.
It's really microwave core tranies any good for OPT?
Nice having you around!!! |
|
|
| Sch3mat1c |
No, nukers aren't going to be any good (just regular NOSS I would think), but it's all I gots that's big enough... But, lemme put it this way: they are gapped, so I won't have to worry as much about saturation (though µ will be low). ;)
Tim |
|
|
| resident |
I push the CLICK HERE NOW buttons and...nothing. :bawling:
Why? :(
Bravo choky!Nice links. |
|
|
| audiousername |
Gee, a thread back from the (un)dead!
The original source of that list seems to be this document prepared by Craig Ryder. Obviously a lot of effort has been made in preparing it, and there are many links worth having a look at.
If someone has problems with the Microsoft Word document format, I should be able to convert it to pdf and post it here
P.S. The "Click Here Now" buttons seem to be popping up in most of Tim's old posts. It's probably to do with the server he was hosting the images on originally. |
|
|
| audiousername |
Ah, I think I might have found the schematics (well, it's the only 6146 PP schematic on Tim's site :) )
 |
|
|
|
|
