Pass ALEPH HYBRID!!!!! (ECC88 in the first stage)

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That looks like a really nice design, but there is one important difference from the Aleph.

The Aleph uses a dynamic current source that adjusts itself based on feedback from the output. This allows it to achieve a near 50% efficiency.

The hybrid design uses a more conventional current source loaded single ended design and will thus only be about 25% efficient.

Not a big deal for the DIYer; it only means you'll need more heatsinks, but it'd be more difficult for a manufacturer.

The design actually looks more like a tube differential input stage connected to a Zen amp used as the output.

-Jon
 
This circuit is one of a half-dozen that pop up at intervals. The concept is interesting, but the execution is poor. Direct connection of tubes to solid state devices can be done, but it's difficult to do reliably and tends not to sound very good. Most hybrid circuits seem to show the weaknesses of solid state and tubes, not their strengths. You'll be better off going all solid state or all tubes, depending on what you're trying to accomplish.
The people who come up with these circuits tend to feel that they're the greatest thing since sliced bread, but then that's human nature.
For the record, I've got one or two hybrid circuits that I keep meaning to try, but that doesn't mean I've got very high expectations for them--just something I'll putter around with some rainy day when I don't have anything better to do. No one would be more surprised than me if they ended up sounding any better than mid-fi.

Grey
 
GRollins said:
Direct connection of tubes to solid state devices can be done, but it's difficult to do reliably and tends not to sound very good. Most hybrid circuits seem to show the weaknesses of solid state and tubes, not their strengths. You'll be better off going all solid state or all tubes, depending on what you're trying to accomplish.

Grey

That's probably true in this case (IMO), but not as a general rule. It depends on what the nature of the hybridization is. For example, a couple of bipolar transistors configured as a CCS cathode load in a tube diff amp can result in a much better circuit than one can get with tubes alone.
 
For the life of me, I can't think of a single classic circuit that's been hybrid. They're all either pure tube or pure solid state. Can you make a hybrid circuit that works? Of course. But it's usually just a mediocre circuit when you're done. Perhaps an interesting technical exercise--gee, look what I can do--but a great-sounding piece of gear? I ain't holding my breath.

Grey
 
Audionics BA150. Berning TF10. Morgan Jones's Crystal Palace. Curcio ST-70. Audio Research SP11. To name a few off the top of my head.

And you cannot seriously convince me that all the satisfied tube dudes with CCDAs in their power amps are deluding themselves.
 
Hmmm, you guys obviously use the term classic to mean something very different from what I mean.
By classic, I mean a design that has stood the test of time...not the flavor of the month at Stereophile or Absolute Sound. Think Dyna ST-70, for instance. CJ Evolution...oh, puhleeze...just because it went into production (even from a well known manufacturer such as CJ or ARC) doesn't make it a classic. Sure, there are lots of pieces that made it into production (no one has mentioned Counterpoint yet), but that does not in itself confer classic status on an item.
And, yes, JFETs make a nifty front end to the phono stage in a preamp, but I was talking about amps, seeing as how that's what the thread started with.
Satisfaction is a curious thing; not necessarily related to classic status. Take the Gain Clone, for instance. Lotsa people have built them and many are satisfied. Does that make it a classic? Hardly. Face it, most DIY folks are happy as clams if sound comes out the back end of something they made with their own two hands. I think of it as a variation on Beranek's Law--that if you made the parts choices, ordered the parts, paid the bill, soldered them in, etc. then to you it's the best sounding thing in the world. Very, very few DIY folks have sufficient experience or detachment to view their projects at all objectively.

Grey
 
Well, if by "test of time" you mean something made previous to 1970, you're certainly right. We didn't have suitable devices then. But the SP-11 and TF-10 were certainly not "flavors of the month." They were around for years and got continuing great reviews. Curcio's designs as well.
 
People use the word 'classic' rather freely. The phrase 'instant classic' is, in my opinion, an oxymoron, but that doesn't stop people from using it on a daily basis. It takes time to prove worth. I mean, really, how many times have reviewers gone ga-ga over a circuit, only to have it fall into a black hole before the next issue hits the stands, never to be heard from again. Arguably every issue of every stereo magazine has at least one such review, and usually more, right?
Consumers run on a slower schedule. They have to. They spent hard-earned cash on the gear and have to wait a while to let their wallets/pocketbooks recover. Add to that the all-too-human tendency to proclaim satisfaction with something that cost them so much money and it takes a while before they go out and plunk down more money for a new amp. So how many people buy a hybrid amp and love it so much that they go out and buy another when it's time? Few. Very few. Case in point--I know a guy who's stuck with an Evolution amp. He's not really happy with it, but he's got to keep it because he can't admit to his wife that he dropped that much money on something that he's unhappy with. Classic? No way. Now, the Premier One was a classic. Wish I still had mine, but that's the way life goes.
Perhaps that's a good starting point for a definition of the word classic: Equipment you used to own and wished you still had. Old Quad ESLs (not amps, I know, but they are clearly classics), ST-70s, stuff like that. Though I've never owned either Quads or an ST-70, I'd buy either one without question if I came across one in good condition and the price was right. Other gear I would be a lot less likely to jump on.
While we're on the topic, there are some relatively new thoughts on hybrid circuits over at www.tubecad.com. I'd be willing to bet that Broske's circuits would beat the one at the beginning of this thread hands down. He's a clever guy, and that's not something I say every day of the week. He earned my respect the hard way--by coming up with neat ideas and thinking things through. And he actually listens to things, too. Imagine that! It's refreshing to have someone around who both thinks and listens.

Grey
 
I am glad i got rid of the Rogers 3/5A's !!!
Then, i still have the ESL63's and my first DIY loudspeakers.

Maybe i have the chance to ask NP to take the Aleph-NULL-s off my hands.
Clearly, by the definition, the 0s does not rank any position in the divine list of classics.
But i still have it, and it cost me mucho dinero to buy one !

My dad built a record player for a reverend in the 1920s, in those days decent record players were absent.
15 years ago my youngest sister's boyfriend gave me an old Thorens player.
The same week i had a chat with "my father" about tweaking the thing, he told me the reverend story.
As my dad owned a factory with all the machinery needed for building record players in the ranks of Zarathustra's, Goldmund's, VPI's, Transrotor's and the like i asked him to produce the hardware for transforming the Thorens in a contemporary "state of the art" recordplayer.
By classic standards i must have raped a solid bit of audio history, the original Thorens today ranks high on the turntable drool list.

I hope the audio design benchmarks remain on the exhibit of the NY museum of modern art.
I still do desire to own a couple of Quad II tube amps one day.
But, the ESL's are very pleased with an added subwoofer unit underneith.
So, undoubtebly i'd wrench the Quad amplifiers to turn them into Mark 2000+.

The Dynaco, Leak, were nice to play with. I agree that some may well be kept original.
However, i believe that audio equipment is not original from the start as they re-produce sound.
The idea of audio science, which applies for the DIY audio scene too, is to achieve the highest level of reproducing the original.

I grew up listening to tube radio's. I still enjoy the sound once in a while, for nostalgic sentiments.
Given the option i'd prefer my first diy builds, i'd cherish the 0s even more.
(did i say More? :clown: )
 
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