• 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.

The worlds least efficient amplifier

Status
Not open for further replies.
Jump to Latest
Jeb-D.

Jeb-D.

Member
Joined 2005
diyaudio.com/forums/swap-meet/157276-garage-sale.html#post2023179
#1
Quite possibly that is.

Thought I'd share the schematic since I'm finally; pretty much done, tweaking with it. I'm sure some of the sand masters will laugh at my screen regulator, but it seems to be doing the job quite well.

Puts out 14-16Wrms (varies between output tubes). Uses 3dB of NFB. Its -3dB between 70-80kHz. It relies on harmonic distortion cancellation. So the distortion characteristic varies depending on how you set the input pentodes Vg2.

Overload characteristic is quite good, especially for a cathode biased amp. There are a few things going on which may be hard to notice at first glance. These "tricks" significantly reduce blocking distortion when the amp is over driven (even with the larger sized caps).

I can post some measurement data if there is any interest.

Best Regards and Happy Holidays. Booze it up responsibly😉
An externally hosted image should be here but it was not working when we last tested it.
 
Last edited:
#2
Pretty cool Jeb! Novel somewhat RH like feedback arrangement.. (CF inside the feedback loop)
Wondering about LED bias on the pentode, wonder how that would that affect your distortion canceling?

Here's the amplifier that I once nominated as the world's most inefficient amplifier.. Six 6C33-C-B per channel, and I never succeeded in getting more than 25Wrms per channel out of them. The power target was 120W into 4 ohms, and about 200W into 8 ohms.. They were quite effective voice coil fryers.. Sadly they never reached fruition because I this was about the time I started to get interested in SE amps, and ultimately after sitting in storage for years I gave them away - they were subsequently scrapped for the custom power transformers.. Here: http://www.kta-hifi.net/projects/amp_page/6c33amp/6c33.html

I suspect I would like your's a lot better..

Have a great Holiday!
 
Last edited:
#3
Jeb-D. said:
Quite possibly that is.
Click to expand...

No not really. For pure inefficiency, you can't beat a resistor-loaded parafeed. You'd be lucky to hit 10% with that.

I'm sure some of the sand masters will laugh at my screen regulator, but it seems to be doing the job quite well.
Click to expand...

It isn't a regulator. It's an active decoupler (a.k.a. capacitance multiplier). Serves to isolate the load from any AC riding on the DC rail. Used the same idea with very high gain SS amps to prevent instability. It's also a good way to replace heavy and expensive ripple chokes. Done that too.
 
#4
kevinkr said:
Pretty cool Jeb! Novel somewhat RH like feedback arrangement.. (CF inside the feedback loop)
Wondering about LED bias on the pentode, wonder how that would that affect your distortion canceling?

Here's the amplifier that I once nominated as the world's most inefficient amplifier.. Six 6C33-C-B per channel, and I never succeeded in getting more than 25Wrms per channel out of them. Sadly they never reached fruition because I got interested in SE amps, and gave them away - they were subsequently scrapped for the custom power transformers.. Here: 6c33

I suspect I would like your's a lot better..

Have a great Holiday!
Click to expand...

I went the same route; OTL to SET. My OTL failed as well. It was my own experimental topology. It did put out 20W with 1 pair of 6C33C's and it had good steady state/ sine wave performance. However it had some really strange transient behavior.

The LED would probably change the distortion characteristics quite a bit (as would bypassing the resistor). I had to try several different loads on the pentode before I got the desired behavior. The LED could probably be done with good results, but you would most likely have to re-tune the plate load on the pentode.
 
#5
Miles Prower said:
It isn't a regulator. It's an active decoupler (a.k.a. capacitance multiplier). Serves to isolate the load from any AC riding on the DC rail. Used the same idea with very high gain SS amps to prevent instability. It's also a good way to replace heavy and expensive ripple chokes. Done that too.
Click to expand...

Technicalities 😉 The DC output impedance is also low enough to prevent Vg2 DC voltage from moving around.
 
Last edited:
#6
Re. low efficiency, my SE OTL probably beats almost anything.
It employs 4x PL504/channel in a choke loaded CF topology and consumes over 200W constantly to produce 2x 0,75W @ 8R. Not very eco in any sense of the word, sounds quite good though.
 
#7
Fuling said:
Re. low efficiency, my SE OTL probably beats almost anything.
It employs 4x PL504/channel in a choke loaded CF topology and consumes over 200W constantly to produce 2x 0,75W @ 8R. Not very eco in any sense of the word, sounds quite good though.
Click to expand...


Just wondering if that 0.75W is a typo or is it really just 750mW? I guess that would have to win the award for world's most inefficient amplifier, or the world's most musical space heater.. 😀

Merry Christmas!
 
#10
Steve Bench had an amp on his web page that may realy take this prize. I believe he
used 16 6as7's in inverted mode for ~ 16w single ended otl power and it only burned about 540w! per mono block! My memory isn't all that good I may be wrong about that power output it might have been more like 8w. I am sad to say it looks
like that web page no longer exist.
 
#11
woody said:
Steve Bench had an amp on his web page that may realy take this prize. I believe he
used 16 6as7's in inverted mode for ~ 16w single ended otl power and it only burned about 540w! per mono block! My memory isn't all that good I may be wrong about that power output it might have been more like 8w. I am sad to say it looks
like that web page no longer exist.
Click to expand...

Yes, his original site is long gone, but it has been fully mirrored here:

Steve's Tube Pages

Thread on subject here: http://www.diyaudio.com/forums/tubes-valves/132421-mirror-steve-benchs-site.html
 
#15
Crazy 100 kg amp

There is one crazy tube amp built in Russia, it weight 150 kg and outputs only 6W RMS. Designer of this monster is shizo-tweako who (as usual 😀), claims to be the only single man on earth who discovered how properly construct tube gears.😱

His last model "Maestro Grosso" has only 1.1% efficiency, and new one (in development) only 0.3%.

if the last go into mass production, Russia as the biggest oil/gas exporter may be forgotten once and forever😡
 

Attachments

  • 72890695.jpg
    72890695.jpg
    157.3 KB · Views: 285
Last edited:
#16
LinuksGuru said:
There is one crazy tube amp built in Russia, it weight 150 kg and outputs only 6W RMS. Designer of this monster is shizo-tweako who (as usual 😀), claims to be the only single man on earth who discovered how properly construct tube gears.😱

His last model "Maestro Grosso" has only 1.1% efficiency, and new one (in development) only 0.3%.

if the last go into mass production, Russia as the biggest oil/gas exporter may be forgotten once and forever😡
Click to expand...

Mad people are not that bad if they just simply exist and don't spread their madness to others. But there, in Russia, a whole site's community seem to went mad (audioportal.su) - they do not tolerate those thinking different, ban and opress them, like a typical sect 🙁 Used to be an old member to that site, but approx. a year ago had to give up and leave from there, as one not willing to support the ruling idea of the Party (similar to what have happened in former USSR - either join the party, or die). This is the newest fashion, "proven" to be true by "witnesses" and a very disappointing trend in general.
Now, everyone is going to be curious - what's behind? Of course - it's business, what else can be? But, we're smart enough already, so it's not so easy to sell your stuff without proper amount of b@llsh@t following the product. One of that monsters cost around $150K, if I'm not mistakin'... Therefore there are huge "theories" ('coz we aren't believers, right?) behind - why it's so necessary to have excessive "gigafarade" caps in PSU's and cathode bypasses, as well as excessive OPT's that can go down to 0,7 Hz at -1 dB and up to 200 kHz. Also, being Parralel SE in nature, these amps facilitate matched tubes, selected out of thousands, of course 🙂 "Theories" are explaining, why the non-audible part of the spectrum affects the sounding, and therefore is necessary for the "True Audiophiles"... And in Russia, historically, nothing is valuated more, than being "true" and better than the other, so such meaningless things can be sold.
 
#17
About 30 years ago I say a listing of a couple of far out tube amps in Audio magazine. I don't rember the company name of exact specifications but it
went something like. 10W triode amp 40 lbs, pump and compressor 380lbs !!!
Hay that was many many beers ago and I probably have the weights way off
in fact the pump and compressor may have been 720lbs all I rember is thinking
the casual thief is going to have a hard time steeling the whole thing!
 
#18
Vikt0r said:
Mad people are not that bad if they just simply exist and don't spread their madness to others. But there, in Russia, a whole site's community seem to went mad (audioportal.su) - they do not tolerate those thinking different, ban and opress them, like a typical sect 🙁
Click to expand...

Podobnaja publika - prosto sboriwe tuporilih wizofrenikov s maniakalnim urovnem samovnuwenija. Metodi le4enija nauke neizvestni :t_ache:
 
Status
Not open for further replies.
Top Bottom