single ended amps
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Hello,
This excellent sticky I am sure covers it ..
http://www.audiokarma.org/forums/showthread.php?t=163570
Frannie
This excellent sticky I am sure covers it ..
http://www.audiokarma.org/forums/showthread.php?t=163570
Frannie
mhardy6647
Lunatic Member
No difference except that in parallel SE, there two or more output devices applied in parallel, to provide for increased output power. For transformer coupled SE, the input impedance of the output transformer primary has to be adjusted to allow for the paralleled output devices (e.g., halved to accommodate two paralleled outputs).
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BeerCan
Tá mé ar meisce.
You guys forgot the most important part, single ended amps sound better.
I am just recently finding this to be true. I have drunk the kool-aid so to speak. Or at least my new se amp sounds better than what I had
Single Ended = $
Single Ended Parallel = $$
(I kid, I kid - I know somebody will be along shortly to point out that there are inexpensive SE/SEP rigs out there)
mhardy6647
Lunatic Member
One gets what one pays for.
Redboy
a few good watts
This is true. However, if one pays only for parts, one can have one crazy good amplification device.
mhardy6647
Lunatic Member
I know, I have one of yours...
Thanks! I'll keep that in mind! :scratch2:
That all depends, I was just reading some post the other night and asked a few questions about an amp a member here built. I was ready to start a project till I found out the cost, not cheap by any means. He used some big 833c tubes so they require some pretty high voltages, but he has the same speakers that I own and they need a decent amount of current. The tubes were reasonable but the Iron was very expensive, $11,000 dollars in DIY amps is not my idea of inexpensive.
Maybe I might try building some mono blocks using the 211 tubes, they seem to be a fairly good tube, I am really wanting to start a project.
btol
Well-Known Member
Squidward was able to build this for me: http://www.audiokarma.org/forums/showthread.php?t=592801.
SEUL/Triode Strapped, uses el84's, $400 to my door.
SEUL/Triode Strapped, uses el84's, $400 to my door.
jazbo8
Well-Known Member
Magz's project is not for the faint-of-heart, the HV needed is pretty scrary. OTOH, the 211 seems rather low-power for the task, you would need to parallel quite a few of them to drive the Infinity, so the filament requirement would be quite a challenge. For transmitting tubes at more reasonable HV voltage, the 13E1 seems to be a pretty decent choice, you can check out some of Patrick Turner's designs.
I own an Audionote Kageki (uk) parallel single ended triode (2a3) amp. Even with two tubes per channel, these monoblocs only output about 6 watts per channel. I like the sound of this amp very much--expansive soundstage, extremely good dynamics (lively sounding), harmonically dense sounding, and clarity without being excessively lean or brittle sounding.
I had an amp designer/builder over and he heard my system. He commented that the amp sounded very good and he would love to build and sell parallel SET amps himself, but, he found them to be problematic. He said that he could never overcome the problem of the two tubes becoming quickly unbalanced, with one tube ending up doing all the work. This has been a problem other designers have remarked about as well. Purist will also say that using more than one tube muddles the sound and detracts from clarity. That probably is true to some extent; it is a tradeoff made to gain more output.
I had an amp designer/builder over and he heard my system. He commented that the amp sounded very good and he would love to build and sell parallel SET amps himself, but, he found them to be problematic. He said that he could never overcome the problem of the two tubes becoming quickly unbalanced, with one tube ending up doing all the work. This has been a problem other designers have remarked about as well. Purist will also say that using more than one tube muddles the sound and detracts from clarity. That probably is true to some extent; it is a tradeoff made to gain more output.
That will inevitably be a problem if the two valves are sharing one bias voltage or one cathode resistor. However, it is possible to design round that problem.
The most obvious reasons for paralleling any topology that I can think of would be for power and/or impedance considerations.
I think the specific practical reason we see so many modern parallel SE topologies compared to PP is that in order to get more power out of a tube amp you either have to move up to the next class of power tube, or parallel them. Consider that anything north of 500VDC starts to look a little scary in terms of components, safety, etc. At that voltage you can find a lot of PP amps that put out well over 30WPC. A lot of SE amps in that voltage range put out around a dozen. To get more power from SE at those voltages a lot of manufacturers parallel the devices. It makes a lot of sense, especially in the case of tubes like 45 or 2A3 where the non-paralleled version puts out so very few watts as to restrict the real-world compatibility to a narrow speaker class. A lot of people read about the "magic" of a certain tube, want to try it for themselves in SE, and simply can't because their entire system has evolved in a completely different direction up to that point.
This is not to say that paralleling output devices is a cure-all for the power problem. There is a trade off between complexity of circuit, and power gains realized. A simpler circuit will result in the natural imbalances between the tubes disproportionately favoring one tube, which then gets run harder, which exacerbates the problem, and you only realize a fraction of the power gain expected.
A more complex circuit could do all sorts of stuff to smooth over tube matching efforts, but in my opinion at that point you start to move away from the simplicity and purity that single ended amps are known for. If I needed more power from a specific tube, I'd just go and make it push-pull at that point; Then again that's just me.
I think the specific practical reason we see so many modern parallel SE topologies compared to PP is that in order to get more power out of a tube amp you either have to move up to the next class of power tube, or parallel them. Consider that anything north of 500VDC starts to look a little scary in terms of components, safety, etc. At that voltage you can find a lot of PP amps that put out well over 30WPC. A lot of SE amps in that voltage range put out around a dozen. To get more power from SE at those voltages a lot of manufacturers parallel the devices. It makes a lot of sense, especially in the case of tubes like 45 or 2A3 where the non-paralleled version puts out so very few watts as to restrict the real-world compatibility to a narrow speaker class. A lot of people read about the "magic" of a certain tube, want to try it for themselves in SE, and simply can't because their entire system has evolved in a completely different direction up to that point.
This is not to say that paralleling output devices is a cure-all for the power problem. There is a trade off between complexity of circuit, and power gains realized. A simpler circuit will result in the natural imbalances between the tubes disproportionately favoring one tube, which then gets run harder, which exacerbates the problem, and you only realize a fraction of the power gain expected.
A more complex circuit could do all sorts of stuff to smooth over tube matching efforts, but in my opinion at that point you start to move away from the simplicity and purity that single ended amps are known for. If I needed more power from a specific tube, I'd just go and make it push-pull at that point; Then again that's just me.
Wigwam Jones
Caesar non supra grammati
Simple terms that make sense to me as a tube newbie:
One output tube per channel = single-ended.
Two output tubes per channel = push-pull or single-ended parallel.
Two tubes per channel are only push-pull if each one handles one half of the 'cycle' of positive to negative. Meaning like bicycle pedals, when one is up, the other is down.
If the two tubes act like one big tube, meaning they each handle both sides of the voltage swing in unison, then they are single-ended parallel.
Tube guys, how'd I do? I know there is lots more to it, but that's a 'basic topology' answer without delving into the intricacies of phase splitters and the need for air gaps in output transformers, multiple pentodes in one bottle, and etc.
jazbo8
Well-Known Member
+1 for applications like driving low sensitivity, power-hungry speakers like the Infinity mentioned above, push-pull would be easier to do than PSE unless you have the big budget and/or skill like Magz. I did not know this, but the Infinity RSIIb has a nominal impedance of 4 Ohms, and dips to a mere 1.4 Ohms at 9kHz - try driving that!
ScaleAutoArt
Super Member
You guys forgot the most important part, single ended amps sound better.
:thmbsp::thmbsp::thmbsp:
I rotate Vaughn's creation, a Morrison Micro 2A3 amp, into my office system on a regular basis. For intimate listening, nothing even comes close...
