Some of Bruces thoughts

[MyOwn]

So I'm a TS lover....If you read through the post "Really not that long" Bruce comes through....

http://tubehifi.websitetoolbox.com/post/newbie-to-kitswhich-one-8178509?&trail=15

Edited July 27, 2016 by Steve_S

[NOSValves]

Hmmm 4 days without a comment I wonder why

[CECAA850]

The tube section is one of the slower areas of the forum.  There are many members who have and love TS gear, myself included.  Maybe the link just isn't that provocative?

[tube fanatic]

The tube section is one of the slower areas of the forum. 

That's because the solid state guys don't know what they are missing!!!

 

The link that Steve posted contains a link to part 1 of Eddie Vaughn's well known article on amplifier types and their supposed good and bad qualities.  If nothing else, reading the intro in part 1 is worth doing as it is a total riot:

 

http://www.x3mhc.no/dokumenter/SE-v-PP-Part1.pdf

 

http://www.x3mhc.no/dokumenter/SE-v-PP-Part2.pdf

 

One might get the impression in part 1 that Eddie favored push-pull amps over SE types (and I totally disagree with some of his assertions about SE, such as short tube life).  Yet, his single ended triode strapped Carina EL84 amp, and DRD 2A3 amp, received rave reviews from those who heard them.  I don't know if he ever designed and built any push-pull amps for home audio use (he was very involved with guitar amps at one time). 

 

Each type of amp circuit has it's virtues, and it's simply a matter of listening to them to quickly determine which is most pleasing to your ears.  With Klipsch speakers requiring so little power to produce prodigious output levels, the tube amp options are limitless.

 

 

Maynard     

[erik2A3]

Steve, disregard the negative commentary. I have followed Rozenblit's work since the early 90s, and around that time built from scratch his very first line stage -- a very decent SRPP, dual output (hi and low output impedance) line stage preamp. It had been published in Glass Audio magazine, which, along with Speaker Builder, was a subscription that dealt primarily with DIY vacuum tube audio electronics. I subscribed to both and now very much miss them.

The majority of builders on this forum, including myself, picked up some of the basics from others kind enough to take the time to teach and share. Bruce has both the engineering background and creative insight to both conceive of and realize OTL (for those not familiar: output-transformer-less) circuits that make conventional output transformer-coupled designs seem (to me) rather simple by comparison. The output transformer in more common designs is needed in hollow state audio electronics as a means of coupling the high impedance of vacuum tubes with the much lower impedances of modern loudspeaker voice coils. To some ways of thinking, the output transformer is considered a sort of necessary hindrance -- one more source of possible coloration and signal degradation through which an audio signal must pass. The output transformer must also contend with not only AC audio signal components, but also the power supply - which is not ideal, and something dealt with by a number of designers through the use of shunt or parallel feed output topologies. The was an output circuit that separates power supply artifacts from audio through the use of a dedicated output transformer (only) for the power tubes, and a large choke connected to the plate of the output tube. I have built more than one such design using common big triodes, and the sonic dividends over conventional transformer coupling are in my view considerable.

OTL is the logical next, but significantly more difficult step to doing away with the output transformer altogether. I was just reading an article/interview of a well-known deaigner yesterday, who (and I paraphrase) said essentially that there is no capacitor that is better than no capacitor at all -- something to which I also strongly agree, but it takes more specialized know how to design direct-coupled circuits where there are no coupling capacitors needed.

And that is a very similar view of OTL designers. No output transformer, whether wound with pure silver or gold, is as good as no output transformer at all. As someone who owns several examples of both topologies (including both single-ended and push-pull) I am in the position to easily compare their differences. I have built, repaired, and own very good sounding transformer coupled amps (again both SET and PP), but if in the position to have to choose on sonic attributes alone, the OTL in general and single-ended OTL in particular would get my nod. Bass control, in particular, is truly outstanding. All my oipinion.

I'm with you on Transcendent Sound. Some designers develop one or two products, and occasionally slight variations on those essential designs. And then stop. Bruce Rozenblit is constantly and successfully developing entirely new circiuts within his chosen realm of the OTL amplifier.

Edited July 27, 2016 by erik2A3

[Ski Bum]

Interesting comments from Vaughn on the parafeed style output (last page of the second article).  Is it true that parafeed amps don't offer the clarity and detail of a traditional SE arrangement (presumably due to DC offset in the opt, keeping it charged at all times, unlike a parafeed, which has to switch polarity just as the pp opts do)?  Seems he prefers traditional air gapped se opt (or otl, reading between the lines).

 

Whatever happened to that guy, anyway?

 

I've been curious about the parafeed approach, considering building a cheap version, or, if more money appears in my account, maybe a full blown Horus with the Magnaquest iron, but not if it can't out-do that kooky crystal clarity of a plain ol' tranny coupled SET.  Thoughts?  I know that you guys have lots of actual experience with these variants.

Edited July 27, 2016 by Ski Bum

[erik2A3]

Not in agreement on the idea that parafeed (as Doc B. used the term) do not have the clarity of traditional SET. Quite the contrary in my experience, actually. I built Lessard's Horus....what was it, something like ten years or so ago now? And discussed my observations about it's absolutely stellar performance in terms of those very elements - extreme clarity compared to the other SET amps I had been using before I built the Horus -- and then a modified version of the same circuit. The other amps were the classic Welborne Labs Moondogs, which I still own. I also bought the Moth Audi si2a3 from Moth Audio's Craig U. (now of Eddie Current) in the form of a chassis, transformers, and box of parts. The Moth is direct coupled, and came closer to the sound of an OTL, but not so much as the Parallel feed Horus.

DRDs are also very fine, and I built both the 2a3 and 45 versions for users in other countries. DRD combines direct and interstage coupling, along with the so-called Ultrapath connection on the output. That was designer Jack Eliano's term for it, but it is not new (nor is parafeed, for that matter). Both go back to the very early years of tube audio. I mentioned all of this years ago here, when writing under another handle.

[erik2A3]

Ski Bum,

Whether one component of ANY type can "out do" another is always going to be entirely subjective, including each and every statement I have made above. All components will also add their own specific colorations in more or less obvious ways, and it seems the best we can do is choose our own preferred sets of compromises and colorations.

That someone is able to build a component - preamp, amplifier...whatever - does NOT by any means qualify that same person to be able to declare what's better or worse -- accept what's better or worse to them. They are making judgements specific to their own aesthetic sensibilities and are thus nothing more than opinions. My wife likes Ketchup on fries, I prefer mayo.

[CECAA850]

My wife likes Ketchup on fries, I prefer mayo.

 

That's just nasty.

[erik2A3]

To you.

Edited July 27, 2016 by erik2A3

[MyOwn]

What about mustard??? :ph34r:

 

erik2A3....It takes a lot to get under my skin...

I built 2 of his products, put them in a rack with a DAC, a MAC Mini with ChannelD Pure Music, and hung a pair of RF-7ii's on it. It's amazing "to me" the sound that comes from this combination.

[CECAA850]

To you.

 

 

Isn't mayo on fries big in France?  I swear I've heard of people doing that somewhere else.

[CECAA850]

....It takes a lot to get under my skin...

 

Me too but the typo in the title is killing me

[MyOwn]

 

....It takes a lot to get under my skin...

 

Me too but the typo in the title is killing me

 

LOL, I didn't even notice until you said something LOL....Thank You :emotion-21:

[erik2A3]

True enough about popularity of mayo on fries -- very common in the Netherlands, as I've seen the many times I've been there. BTW: Surely one of our national favorites (at least it's one of mine!) potato salad is much better with the mayonnaise in most recipes than with the same amount of Ketchup!

[CECAA850]

potato salad is much better with the mayonnaise in most recipes than with the same amount of Ketchup!

 

On this we can agree.  Potatoes have to be fried in one manner or another in order for me to use ketchup them. 

[richieb]

Straying a bit from the technical to the physical I have owned and greatly regret selling the Eddie Vaughn El84 Carina. I believe I had Belles and/or Corns at the time. A tremendous amp which projected a sound far and above its 2 watt rating. I will snap up the next one I see for sale. Electraprint trannies I believe?

[erik2A3]

Steve, No doubt! That sounds like a very fine setup. GG is a killer linestage for the price. At some point you might consider the 300B headphone amp/preamp. A more involved build than the GG to be sure, but a truly spectacular product.

BTW: As good as the TS OTLs are, there are of course other, perhaps even more widely known brands that employ the same approach -- Atma-Sphere and Tenor Audio being two that immediately come to mind. Getting one from either of those takes something of a larger investment to get into one's component rack, however. I've looked at the big Atma-Sphere amps from a distance for a long time. That's what makes TS such a truly unique company. Straightforward, functional aesthetics on the outside; extremely competent engineering on the inside - and all at a price approachable to most who are really serious about this pursuit.

It is far more difficult to design exceptionally good sounding and stable (as in circuit stabilty) amplifiers that do not use transformer coupling than to design one that does. Whether one is inherently better than the other probably just depends on who you ask. When I was playing around with modifications of our K-horn crossovers years ago, it bothered me in an academic sense to enjoy the advantages of OTL amplification on the one hand, only to send its signal into an autoformer on the loudspeaker on the other. So, while maintaining the same basic crossover in terms of order of slope and crossover points, I plucked out the autoformer and replaced it with a fixed L-pad and true band-pass for the squawker, as well as separate termination for the tweeter - a cap calculated for 6Khz. I also had a bunch of good magnet wire on hand at the time, so wound my own air core chokes for the band pass and low pass sections. Those were soaked in varnish and allowed to dry a long time.

[erik2A3]

Lol! but my teenage nephew would beg to differ. He won't even touch the most amazing mashed potatoes in the world (lovingly whipped up by my wife and perfectly balanced with salt, pepper, butter, and a glug of whipping cream) unless they are covered with Ketchup, which to me is just, well....whatever. But he loves them, and that's what matters.

[erik2A3]

Maynard mentioned the DRD amplifiers from Welborne Labs and richieb suggests Electra-Print transformers on the Eddie Vaughn amp.

If you don't know and/or just for the record, Jack Eliano was the one who designed the first 300B Direct Reactance Drive amplifier, the circuit and description for which were published in Vacuum Tubs Valley magazine a long time ago.

So, here's the relationship: Jack Eliano is also behind Electra-Print transformers, and thus wound the power, output, and interstage transformers for the DRD amps sold at that time by Welborne Labs. What an intersting and knwledgeable gentleman, as well, not to mention an outstanding artist. He is responsible for many of the great vacuum tube audio cartoon drawings in VTV magazine. Moth Audio also used EP transformers...because they are built to a very high standard.