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SET vs OTL in a shootout ?

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Posted on August 21, 2015 at 14:40:23

trioderob
Audiophile

Posts: 753
Joined: May 15, 2015

anyone do a shootout of the two?

dont get me wrong - I love set amps and had one before probably 90% here.

but man when an OTL amp is firing on all cylinders its something else.

any of you guys do a A/B - same system both amp types ?

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RE: SET vs OTL in a shootout ?

David Lawrence

12:05:12 08/23/15

RE: SET vs OTL in a shootout ?

Tre'

15:29:40 08/21/15

RE: SET vs OTL in a shootout ?

trioderob

15:53:56 08/21/15

...

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RE: SET vs OTL in a shootout ?

David Lawrence

12:05:12 08/23/15

RE: SET vs OTL in a shootout ?

Tre'

15:29:40 08/21/15

RE: SET vs OTL in a shootout ?

trioderob

15:53:56 08/21/15

RE: SET vs OTL in a shootout ?

Caucasian Blackplate

09:23:55 08/25/15

RE: SET vs OTL in a shootout ?

Tre'

17:04:41 08/21/15

RE: SET vs OTL in a shootout ?

trioderob

17:30:38 08/21/15

RE: SET vs OTL in a shootout ?

91derlust

02:35:09 08/22/15

Such as a single WE300B/channel running into a pair of LS3/5As? Nt

Frihed89

03:01:02 08/22/15

RE: Such as a single WE300B/channel running into a pair of LS3/5As? Nt

91derlust

03:28:53 08/22/15

Yes on voices, for sure, transparent too

Frihed89

23:00:16 08/22/15

RE: Yes on voices, for sure, transparent too

91derlust

01:39:41 08/23/15

I generally agree

Frihed89

14:16:09 08/23/15

RE: I generally agree

91derlust

20:21:35 08/23/15

RE: SET vs OTL in a shootout ?

Tre'

17:48:44 08/21/15

I think that you are stuck arguing with "I like" rather than what they can measurably do

richardl

17:01:42 09/09/15

RE: SET vs OTL in a shootout ?

Triode_Kingdom

15:41:45 08/21/15

RE: SET vs OTL in a shootout ?

Paul Joppa

18:40:43 08/22/15

RE: SET vs OTL in a shootout ?

Tre'

21:25:53 08/24/15

RE: SET vs OTL in a shootout ?, posted on August 21, 2015 at 15:29:40

Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002

"any of you guys do a A/B - same system both amp types ?"

Not only same system but same driver.

Circlotron output stage using 4 6as7g's (8 triodes) into a transformer loading the stage at 325 ohms sounds much better than 8 6as7g's (16 triodes) driving 8 ohms (OTL).

It's much more linear, less HD.

Neither sound as good as the SET. The 6as7g is just not all that linear no matter how you load it.

I don't think any of the super low plate resistance tubes (made for pass tubes in series voltage regulator circuits) are.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

http://www.g8wrb.org/data/Svetlana/pdf/6AS7.pdf

RE: SET vs OTL in a shootout ?, posted on August 21, 2015 at 15:41:45
Triode_Kingdom Audiophile Posts: 10042 Location: Central Texas Joined: September 24, 2006	"The 6as7g is just not all that linear no matter how you load it." You're right, but I think that issue all but disappears if the tubes are configured as followers. I really like the concept of transformer-coupled followers for low power applications.

RE: SET vs OTL in a shootout ?, posted on August 21, 2015 at 15:53:56
trioderob Audiophile Posts: 753 Joined: May 15, 2015	dont think I agree with that. at least in a single driver configuration as I am using the 7236 version of that tube which is super hi transconductance. as using in my headphone amp and 600 ohm headphones its pretty astounding having both the speed, prat, detail of SS and the depth and timbers of a good set amp. also holographic like a mesh plate 300b. and a directness thats almost spooky.

RE: SET vs OTL in a shootout ?, posted on August 21, 2015 at 17:04:41

Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002

Spacing. It's all about even spacing along the load line (not shown on either set of plate curves).

I don't see a load impedance (load line) that would give you even spacing with the 7236.

Remember you need to stay below the max plate dissipation line shown.

Even if the load line was horizontal (least HD for a triode) the spacing between the grid lines would not be even. (wide spacing to the left, narrower spacing to the right except for the "burp" between -40 and -50)

If you like the way they sound, that's great! But the tube is not very linear. Certainly not as linear as a 300b.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

RE: SET vs OTL in a shootout ?, posted on August 21, 2015 at 17:30:38

trioderob
Audiophile

Posts: 753
Joined: May 15, 2015

could it be the 1500 feet of output transformer wire that's missing being a bigger factor than the linearity of the tube ?

I am not comparing apples to apples here I understand.

but what I like is a amp that splits it right down the middle.

so at one extreme you have the old tube anps and amps like quikesilvers which to me sounded extremely "romantic and lush" but also slow and marsch mellowey. on the other hand I heard vey high end solid state and difital amps that were ultra detailed and fast but also strident and edgy. they also lacked a big degree of depth on the sound stage. SET were extremely nice but never had the speed on fast transient passages.

OTL seem to split it down the middle. best of both worlds. at least for headphones they are unbeatable .

RE: SET vs OTL in a shootout ?, posted on August 21, 2015 at 17:48:44

Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002

"could it be the 1500 feet of output transformer wire that's missing being a bigger factor than the linearity of the tube ? "

Anything is possible when we are talking about someone's subjective opinion.

I don't see how removing 1500 feet of wire will make the two halves of an output wave form even when the tube itself is outputting them un-even because the plate voltage is moving more (for a given grid voltage change) in one direction vs. the other.

Maybe whatever "ills" the wire is causing is creating something more important to you than low HD?

I'd like to hear more about your "a single driver configuration as I am using the 7236 version" amp. What brand and model number? What circuit does it use?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

RE: SET vs OTL in a shootout ?, posted on August 22, 2015 at 02:35:09

91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014

I don't do "shoot-outs". I might occasionally perform comparisons, but I find them useful only for gross differences. I prefer longer term listening, which has greater external validity...

Now, to the crux of your opinion: "SET were extremely nice but never had the speed on fast transient passages."

I find *Systems* running SET amps can do that to my satisfaction and more. But not if running unsuitable speakers (there is more to it than efficiency and impedance) or an incapable SET amp.

I don't know what you are running - you have nine posts and no system listed - but for SET amps to deliver what you desire, the system should include speakers ideally suited to amps with high output impedance. A near worst case, yet common, example is the classic high Q driver run on an open baffle. Well, they may sound nice, but a little slow, soft and blunted. Floppy drivers without loading that need more control that a SET amp provides. More common and almost as poorly matched are efficient(ish), but under-damped, alignments.

Okay, my point is, SETs can pretty easily do what you ask and then some, but they need to be an appropriate design & build and run in an appropriate system.

It is Saturday night here. Beer and dinner are calling.

Regards,
91

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

Such as a single WE300B/channel running into a pair of LS3/5As? Nt , posted on August 22, 2015 at 03:01:02
Frihed89 Audiophile Posts: 15703 Location: Copenhagen Joined: March 21, 2005	Nt

RE: Such as a single WE300B/channel running into a pair of LS3/5As? Nt , posted on August 22, 2015 at 03:28:53
91derlust Audiophile Posts: 1101 Joined: December 25, 2014	Such a system could probably sound nice, with a glorious come-hither vocal range. Probably not a master of transparence and dynamics, but hey, I have not heard it so could be wrong... After all, it is the final result that matters. "Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

RE: SET vs OTL in a shootout ?, posted on August 22, 2015 at 18:40:43
Paul Joppa Industry Professional Posts: 7295 Location: Seattle, WA Joined: April 23, 2001	As a follower, the 6AS7 has maybe 6dB feedback, so the linearity is only a little better. Most OTLs use substantial added feedback to get acceptable damping factors; that might have a comparable effect to the topology.

Yes on voices, for sure, transparent too, posted on August 22, 2015 at 23:00:16

Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005

I have a pretty good 300B power amp with double C-core OPTS and on soloist + guitar, it is both extremely linear, transparent and engaging. Also on solo instruments. No, my experience is that nothing can keep up with fast, complex piano passages, or the dynamic swings of the likes of Mahler, compared to what one hears in a concert hall. But the LS3/5As give a pretty good orchestral presentation as a whole.

RE: Yes on voices, for sure, transparent too, posted on August 23, 2015 at 01:39:41

91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014

Without having heard your set-up, transparency from the upper bass and above could be really good. Although the LS3/5a speakers are not bass monsters, the bass probably does not draw much attention to itself. Still, I reckon those double-C cores in charge of some nicely-matched refrigerators would be capable of some really decent bass. ;^)

As for keeping up with Mahler and similar, I'd say that although we can't convincingly reproduce most music, some systems can do it more convincingly than others. That said, our systems should reproduce to our liking those things in music that matter to us... the things that make music meaningful. It sounds like your system does that for you!

To clarify my initial response, I believe SETs can have acceptable (for me) speed on quick transient passages. This should be well achievable from the mids through to treble. However, to achieve this in the bass, the speaker alignment needs to be suited to the high impedance output of a SET amp. A speaker designed to sound balanced when used with a low impedance source will generally sound a little too weighty, slow and soft in the bass when driven by a SET amp.

Regards,
91

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

RE: SET vs OTL in a shootout ?, posted on August 23, 2015 at 12:05:12

David Lawrence
Audiophile

Posts: 315
Location: North Dakota
Joined: April 23, 2007

I've had Atma-Sphere M-60 and Transcendent T16 OTL's and a variety of SET amps, as well as push-pull pentode and tetrode amps. I agree that the OTL's probably can be the fastest and perhaps the most spacious sounding amps. However, all three types can sound great and without stereotypical shortcomings, when matched with the right speakers. Better SET amps may be the most musical, and definitely need not be slow. I think my SE 300b amps with Tango transformers and C3M drivers (following Thorsten), grid chokes, etc. are very fast and transparent as well as natural. Also like interstage coupled SE 45, HK Citation II, and am slowly getting together things for DC SE 2A3.

David

I generally agree, posted on August 23, 2015 at 14:16:09
Frihed89 Audiophile Posts: 15703 Location: Copenhagen Joined: March 21, 2005	But bass does not hold my interest as much as what lies between 60Hz and 10,000 Hz. So, I am well matched with my speakers.

RE: I generally agree, posted on August 23, 2015 at 20:21:35

91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014

Exactly my point; you have a system well suited to you. Enjoy!

Actually, I am not exactly a bass fiend; if I were I'd opt for much more displacement and big solid state power. But I do like an effortless and coherent sound, albeit at modest volumes, so my SETs into GPA 604s are fine.

You have reminded me that I need to get moving on my next amp build; a pair of custom nano-crystalline double-c cores are sitting on my shelf awaiting a home!

Keep well,
91

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

RE: SET vs OTL in a shootout ?, posted on August 24, 2015 at 21:25:53
Tre' Industry Professional Posts: 17294 Location: So. Cal. Joined: February 9, 2002	"As a follower, the 6AS7 has maybe 6dB feedback, so the linearity is only a little better." I thought a cathode follower works on 100% local current feedback and thus has gain less than unity? Tre' Have Fun and Enjoy the Music "Still Working the Problem"

RE: SET vs OTL in a shootout ?, posted on August 25, 2015 at 09:23:55
Caucasian Blackplate Industry Professional Posts: 8313 Location: Seattle Joined: June 18, 2004	Your example is much, much different than the typical OTL speaker amp in many important ways. I would say it's not a particularly valuable data point in the discussion.

I think that you are stuck arguing with "I like" rather than what they can measurably do, posted on September 9, 2015 at 17:01:42
richardl Audiophile Posts: 3555 Joined: September 5, 2002	I like and I don't like are opinions and therefore inarguable. However, I think that he is saying that he "likes" the sound of the less linear tube, the 7236 rather than stating that it is more accurate.

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