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Using both section of a dual triode for the driver tube

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Posted on December 8, 2016 at 08:38:59
DAK
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 I was wondering what are the pros and cons of using both sections of the 6SN7 or 6SL7 wired in parallel (or for any dual triode) as the driver for the power tube?
Also what would be the effect upon the tube characteristics. thank you for your help, and a very happy holidays to all, Dak

 

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RE: Using both section of a dual triode for the driver tube, posted on December 8, 2016 at 08:54:30
kyle
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 Double the transconductance, half the plate resistance, mu stays the same

 

..Yes also seeking input..., posted on December 8, 2016 at 09:32:37
drummerwill
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...I'm considering doing the same to the 6SN7 in my Low Powered
6SN7-DC-2A3-IT-845 amp.

I'd like for it to have a little more bite than it presently has !

Thanks
Willie

 

RE: What are the pros and cons? nt, posted on December 8, 2016 at 09:33:35
DAK
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 .

 

RE: What are the pros and cons? nt, posted on December 8, 2016 at 11:23:15
kyle
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 Some people say there is a smearing of detail but I think that the extra current available makes up for any chance of the speed of sound being able to out pace electricity.
I found in the case of 6SN7s that the halves are usually quite well matched and there is no gross imbalance between sections. That's not necessarily the case with a tube like a 6BX7 which can have a greater difference between sections.
Bottom line, it depends on your requirement and who you let make up your mind.

 

RE: What are the pros and cons? nt, posted on December 8, 2016 at 11:27:26
DAK
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 Thank you for replying. In What kind of amp did you use the paralleled 6sn7?

 

RE: What are the pros and cons? nt, posted on December 8, 2016 at 12:08:23
kyle
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 I have used paralleled 6SN7s in SE 2A3 and 300B amps. The other thing, I usually load them with a CCS and LED bias them. Good power supply isolation on top and full mu combined with no cap bypass on the cathode. Heresy for some but the results sound good and you run the tube with a horizontal load line. I use two red LEDs for about -3.5V bias.
With the CCS, a 6SN7 has enough gain for a two stage amp if you use a preamp. If you're using a passive or straight out of a DAC, you should look at the voltage gain available.

 

Another answer, posted on December 8, 2016 at 14:59:06
Frihed89
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 Both sides of a 6SN7GT in each channel of a 300B SET power amp.

 

RE: That seems pretty good to me, posted on December 8, 2016 at 15:45:32
DAK
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 So. you used a single 6sn7 to a 2A3.
Did you make your own CCS?
I mostly use a preamp so sensitivity for the input is not a big issue.

 

RE: Another answer, posted on December 8, 2016 at 15:48:58
DAK
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 Hi Frihed, how did you use the 6sn7 in your amp? What were the parameters?

 

RE: what does double the transconductance do?, posted on December 8, 2016 at 17:49:01
DAK
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 I still don't relate to that term well. I know the definition is Gm = change Iout / change Vin. But when you say that value doubles when paralleling the sections of the 6sn7. In real world terms i don't know what that means.
Or, if Gm doubles while mu stays the same and Rp is halved. I understand what will happen in terms of the math but, in terms of a circuit how does one use that info? thanks for explaining.

 

RE: Another answer, posted on December 9, 2016 at 01:02:42
Frihed89
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 I don't know. It's an Audio Note (UK) Conqueror Silver amp. I've never asked, or looked. It could be an SRPP in front of a coupling cap.

 

RE: what does double the transconductance do?, posted on December 9, 2016 at 05:06:06
Chip647
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 A tube with high transconductance will have a large change in plate current with a small change in grid voltage. Conversely, a tube with lower transconductance will have a smaller change in plate current for the same change in grid voltage.

This means that a tube with high transconductance will reach saturation and cutoff (clipping) much more easily (with smaller grid signals) than one with low transconductance. The graph of grid-voltage vs. plate current (Transconductance curve) may be rather sharply curved, and as a result a signal amplified by a high-gain tube may have more distortion even when it is not driven into clipping.

Tubes with lower transconductance will tend to have a broader curve to their graph, and for small signals may be more linear and have less distortion, depending on where the tube is biased. High transconductance tubes have less ability to drive the next stage miller capacitance.

 

Sonically, its called the " choir effect "., posted on December 9, 2016 at 07:56:25
drlowmu
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 Two halves can NEVER be as pure as a single section.

So, never EVER can, or will, this possibly be, the BEST solution, at least, for the best POSSIBLE sound.

Now .....you have it !!


Jeff Medwin

 

RE: Another answer, posted on December 9, 2016 at 08:02:31
kyle
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 I think it's 6SN7 DC cascade then cap coupled to the 300B. A 3 stage amp.

 

RE: Sonically, its called the " choir effect "., posted on December 9, 2016 at 08:28:08
kyle
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 Using the same level of technical logic and expertise: using a 12ax7 to drive a power triode can NEVER work because of the high plate impedance and low drive current available. It ignores miller effect and sounds wimpy.

Saying NEVER when it's just your narrow minded opinion is NEVER correct.

 

Why do you dismiss the concept?, posted on December 9, 2016 at 08:55:28
DAK
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 In your builds you use multiple hook ups from single sources as in modifying choke outputs with multiple lead outs and modifying output transformers with multiple outputs from the secondary to the speaker. I daresay that paralleling 2 sections within one tube has a better chance of electrical integrity than putting 3 wires on one leadout and having the EXACT same number of electrons coming out of each leadout.
In your builds you parallel components, wires. I dont think paralleling 2 tube sections from a tube that you select for matched outputs is very different, at least in concept.

 

RE: Sonically, its called the " choir effect "., posted on December 9, 2016 at 09:03:50
drlowmu
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 So you, and - some others may think !!

Wrong, wrong, wrong.

Obviously, ANY and ALL doubters have NEVER heard a Serious Stereo amp, in a good setting, play !! It " wiped the floor " in a SET amp shoot out at RMAF ten years or so ago, at Terry Cain's after-hours shoot-out. Dennis' amp got a STANDING ovation.

Kyle, if you properly engineer it, as Dennis Fraker uniquely KNOWS how to do, and if you operate the 2A3 at 43 mA., not 60 mA. at 250 P-K, AND use a direct couple ( the ONLY "way" to go ), and pay CAREFUL attention to ALL aspects of the build, the 12AX7 can easily drive the 2A3.

Or, let me put it this way, Kyle, Using the ABOVE low current driver operating parameters, Dennis' amps THIS year, in 2016, two months ago, were rated by Herb Reichert, Stereophile reviewer, as being one ( of the two ) of his "most favorite" rooms to visit and LISTEN to, at the recent RMAF show, out of HOW MANY ...250 - 300 exhibitors??

Besides the URL on the easy-click at the bottom of my post ( read it first ) look also at THIS following URL, cut and paste it, please scroll down to under the heading " FAVORITE ROOMS "

\\http://www.stereophile.com/content/rmaf-2016-assessment#kyTkLrxdjfMsQ22z.97

So Kyle, What do I need to DO to get credibility with people who have no experience hearing what I am talking about, and who don't fully understand ??? Thats you, AND I am sure - some others.

Regards, best wishes, Merry Christmas

Jeff Medwin

 

RE: Sonically, its called the " choir effect "., posted on December 9, 2016 at 09:16:48
kyle
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 "So Kyle, What do I need to DO to get credibility with people who have no experience hearing what I am talking about ???"

Hi Jeff.
This is a relatively easy question to answer and one you should have asked years ago.
Stop posting your opinions as facts. No matter how many times you repeat an opinion, it doesn't become less subjective.
Stop using the CAPS button to emphasize your opinions. It's annoying and bad forum etiquette.

Two simple steps and voila, instant credibility.

On your behalf; You've been making amps for a long time. I remember seeing you in Sound Practices magazine in the 1990s so you have the history and you've shown everyone pics of your amps for years, so we all know you can design/build. You've shared your ideas to anyone that would listen, so you're helpful.
None of that means that your opinions are suddenly new electrical laws or that they're the only way to do things or that everyone will like the results. That's OK. It's just a hobby and it's supposed to be fun.
I enjoy your posts and enthusiasm as do others so carry on and enjoy yourself as well.

 

RE: Why do you dismiss the concept?, posted on December 9, 2016 at 09:31:04
drlowmu
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 Agree, its NOT different in concept, but VERY different in effect, final result. Passive versus active me thinks. The TUBE is THE active amplifying device.

Ya gotta know when to hold em, and when to fold em.

You can't use two sections, and have it play as well, as pure, as one.

Or, mathematically 1 plus 1 does not equal 1.

This IS always audible, so why argue?? Find a better circuit, I did in late 2016. Seek and ye shall find.


Jeff

 

Far out we agreed. I will take that. nt., posted on December 9, 2016 at 10:30:13
DAK
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 .

 

OK. Thanks, posted on December 9, 2016 at 12:02:01
Frihed89
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 There's a schematic of the Conqueror on the web. I'm not sure how accurate it is.

 

This is a reply from the tube DIY Asylum, posted on December 9, 2016 at 15:10:26
Frihed89
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 This was the reply I got when I posted the circuit from the schematic on the web.

"Looks like DC coupled, cascaded, common cathode 6SN7 sections.

Eli D."

 

Remarkably similar. nt, posted on December 9, 2016 at 17:33:14
kyle
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 .

 

RE: Using both section of a dual triode for the driver tube, posted on December 9, 2016 at 18:23:54
used-hifi
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 IMO paralleling any tube being voltage gain or final tubes they MUST be gain matched, finals MUST be current matched, other wise you will end up with lots of IM distortions possible ghosting but personally never heard this but i have heard IM distortion when not matched or separate cathode resistors.


blumelin comes read up on his ideas



Lawrence

 

RE: as well as entertaining, posted on December 9, 2016 at 19:18:20
deafbykhorns
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 ,!

 

RE: Using both section of a dual triode for the driver tube, posted on December 9, 2016 at 22:00:23
DAK
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 Matching tubes is not a problem for me, i have hundreds of 6sn7 and 6sl7 so not an issue.

 

RE: Sonically, its called the " choir effect "., posted on December 10, 2016 at 02:29:48
SteveBrown
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 You know this subject of paralleled sections has come up many times over the span of this forum. Others as well regarded as PJ have weighed in on the negative side IIRC (forgive caps). I've tried it several times because of the theoretical benefits. All I can say is I don't like it. Things seem smeared. I also know the theoretical benefits of negative feedback but I've heard both ways and I think with NFB amps sound like crap. All are entitled to their opuntia I've never heard a great sounding slide rule. :-)

 

RE: Using both section of a dual triode for the driver tube, posted on December 10, 2016 at 02:31:42
SteveBrown
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 A free lunch!

 

6SU7, posted on December 10, 2016 at 06:20:22
tweakydee
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 Try the 6SU7 tube, this was a premium version of the 6SL7 for the military that had the triode sections factory matched.

 

Well....., posted on December 10, 2016 at 07:14:46
drlowmu
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 All the King's Horses, and ALL the King's men, could never put Humptey together again.

Jeff

 

And yet..., posted on December 10, 2016 at 08:30:58
Ivan303
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One of the best sounding, if not THE best sounding system I have yet to hear, used custom SET Monoblocks using the 304TL as its output tube.

OK, the speakers were 5-way Ale horns, so there is that. ;-)


First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: Sonically, its called the " choir effect "., posted on December 10, 2016 at 08:31:31
kyle
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 "All are entitled to their opuntia" Cactus?

Anyway, I've also read lots of posts on paralleled tubes and it seems like one of those areas where everybody has an opinion, including some very well respected designers. There are also quite a few that double up on output tubes - an area where I can hear a negative difference. I do not however hear a difference in paralleled driver tubes. Not that others can't, I've said before that I'm a tin ear when it comes to many audiophile things.
As an example, I don't attach huge importance to ultra-precise soundstage because I don't hear it in live performances to the extent that some reproductions systems portray it. I have never heard instruments coming from off stage in a live situation but some audio types think it's a sign of added realism when the sound stage comes from outside the speakers in a home set up.
Perhaps using single driver tubes will allow me to appreciate things like this.

 

RE: And yet..., posted on December 10, 2016 at 08:35:51
kyle
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 That's a good point.
By the same token, I listened to bi-plate 2A3s for years before they started making 300Bs with 2.5V filaments and calling them single plate 2A3s. I never felt that they were smearing the music, in fact I still occasionally pop a pair into my amps and actually enjoy the music they reproduce.

 

RE: Sounds like a very good idea!, posted on December 10, 2016 at 09:05:30
DAK
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 I will definitely keep that one in mind. I have a fair number of 6su7 and 6188 to play with.

 

RE:You made your point in the first reply., posted on December 10, 2016 at 09:34:52
DAK
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 No need to be concerned, i am not trying to attack your paradigm. i am just playing with the tools that i have. The problem you speak of is evident in push pull amps yet, millions upon millions are out there being enjoyed by more millions of people. In the end it is all about the enjoyment.

 

That said, I likely will not go with parallel 6SL7 to drive my current 300B SET amp..., posted on December 10, 2016 at 10:27:10
Ivan303
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 going instead with a pentode of some kind.

Also have heard parallel 300B amps that sounded good. As my speakers are 107dB or so horns, I really don't need that much power so one 300B is fine.




First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: And yet..., posted on December 10, 2016 at 12:04:35
used-hifi
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 I think what your getting at here is there are 4 separate sections parelled in this tl304 tube?

and .... and sounded very very good.




I agree on all accounts(opinions)but its all in the details on how its done that's what makes or breaks ideas or in this case paralleling tubes, IMO there is almost always a "work around"


Lawrence

 

RE: Is that why SS sounds like crap?, posted on December 10, 2016 at 15:20:35
deafbykhorns
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 Solid state does the same thing, they basically parallel transistors in most amp circuits. Some manufacturers match transistors which brings us back to the subject of smearing. I think if you match them well enough, most wont notice the difference.

As Lawrence said below, there's always a workaround

 

+ plate impedance is cut.in half (Jeff.SHOULD like that ... Decreased resistance, - tube not utilized for max, posted on December 11, 2016 at 04:23:54
Cleantimestream
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 Functionality.
The Mind has No Firewall~ U.S. Army War College.

 

wouldn't that be good for a 6su7?, posted on December 11, 2016 at 09:11:23
DAK
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 Keep the mu but half the impedance.

 

RE: wouldn't that be good for a 6su7?, posted on December 11, 2016 at 14:35:39
Cleantimestream
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 Yes Sir, I use 6SU7's in a Baldwin circuit that.employs what I deem ingenious regulation ... Only drawback is one cannot Triode wire because of it. If my goal was lower plate impedance, then choose another tube ... One of finest amps I have built uses 417a with LED bias. Dead quiet using 816 rectification

Dead quiet through modified Khorns.


The Mind has No Firewall~ U.S. Army War College.

 

Has anyone mentioned the driver's input capacitance? (nt)e, posted on December 12, 2016 at 06:02:16
Triode_Kingdom
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 nada aqui



 

RE: Has anyone mentioned the driver's input capacitance? (nt)e, posted on December 12, 2016 at 08:42:22
DAK
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 Ok, i did not think about that. I hate to hazard a guess as i have not even considered input capacitance as an issue at all. cheers

 

Getting to the "work around", posted on December 12, 2016 at 09:34:40
DAK
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 Kyle, i believe you mentioned using paralleled sections of the 6sn7 with a CCS and a LED on the cathode. Would you mind going into more detail about your set up as i would like to try something like that in my amp. Thank you.

 

Smeared?, posted on December 12, 2016 at 11:57:40
gusser
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 OK, so I think by "smeared" or "Choir effect" people here mean to say that a second signal is produced due to the unmatched delay of the two tube sections?

Essentially adding a delayed signal back to the un-delayed signal which would produce an echo effect? Right?

Yet nobody to date has shown us the output of such a circuit on a scope where a delay would be very obvious!

Can't be measured? I disagree. We can easily measure time differences down to the pico-seconds on commodity bench scopes. Yet in order to hear such a delay, we are talking tens of not hundreds of milliseconds. That's based on our hearing deficiencies.

Furthermore when you consider the physics in tube construction, the standard manufacturing tolerances are magnitudes lower than would be required to produce such a long electrical delay.

This is layman's logic! Plain and simple. There is no evidence of this phenomenon that can be measured and quantified - because it doesn't exist at audio frequencies.

I don't doubt people hear things they don't like when paralleling tube sections. But I have to ask if the circuit parameters have been adjusted for the good old LCR changes the additional tube section makes? because that's most likely what you are hearing.

 

PM sent nt, posted on December 12, 2016 at 11:59:12
kyle
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 .

 

RE: Smeared?, posted on December 12, 2016 at 16:03:02
SteveBrown
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 I would not question your electronics acumen and as some suggested there may be places where this works just fine, like bi-plate 2A3s, though I note that single plate versions seem in higher demand. When I've paralleled sections it has only been in driver circuits of SE amps, so my experience is limited to that and yes, the circuits in my case were optimized for things like the reduced Rp, why else do any of this? Maybe "smeared" (my term) is a poor application of language to what my ears perceive. What I've experienced are things like less clarity in placement of instruments and less ability to hear individual instruments- as in the case of massed strings, etc. Makes no diff to me if it is measurable because I do this for the enjoyment of music, not because I'm making precision test equipment or such. So if one circuit sounds better to my ears, that's what I will build and yes I'm quite familiar with the engineering theory behind it all.

 

RE: Smeared?, posted on December 12, 2016 at 20:17:22
Tre'
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 "But I have to ask if the circuit parameters have been adjusted for the good old LCR changes the additional tube section makes? because that's most likely what you are hearing."

When paralleling the two triodes of a 6sn7 does the Miller capacitance go up vs. one triode?


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

 

RE: Smeared?, posted on December 13, 2016 at 06:31:45
kyle
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 It goes up but how significant it is depends on the rest of the system.
The preceding stage in my case has output impedance of about 47 ohms and I use a 470 ohm grid stopper. A paralleled 6SN7 has about 8pF of plate to grid capacitance and in the case of using a CCS, a mu of about 20, so about 168pF miller.
I say "about" because the two sections of a 6SN7 don't have the same input capacitance and even with a CCS the mu can vary tube to tube.
So yes it affects the FR but whether it makes a difference is up to the builder and the application.

 

I would expect it to double? (nt), posted on December 13, 2016 at 11:50:00
gusser
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 x

 

Nope ! Not allowed. Find the right tube, with correct mu and low plate resistance. (nt) , posted on December 13, 2016 at 12:03:51
drlowmu
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 Seek and ye shall find. Knock, and it will be opened unto you. Solder, and ye shall breathe-in toxic fumes.


Low Mu

 

RE: Smeared?, posted on December 13, 2016 at 17:01:16
Tre'
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 " So yes it affects the FR but whether it makes a difference is up to the builder and the application."

Yes, that's why I brought it up.

If the drive impedance was high and someone switched to parallel from single and noticed a difference in sound, the sound difference could be do to that.

"The preceding stage in my case has output impedance of about 47 ohms"

but not in your case.


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

 

+1 (nt), posted on December 13, 2016 at 18:24:10
Tre'
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 .
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Nope ! Not allowed. Find the right tube, with correct mu and low plate resistance. (nt) , posted on December 13, 2016 at 19:03:43
Cleantimestream
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 Gee, Jeff, had you read my response to DAK, your retort would have been unnecessary, the 417A, 437A, are in a class by themselves and they have no peer so far as what you are trying to convey. I never considered tying the plates together to lower plate resistance, use another tube is what I said to DAK... You should too, if you are building amplifiers, 12AX7?

Excellent in a preamp position, but it's resolution/clarity in an amplifier compared to say, 417A is pathetic. Too bad you refuse to recognize opinion when you see it. Try building new schemos.

nothing changes if nothing changes.

Although the room trumps any other factor.



The Mind has No Firewall~ U.S. Army War College.

 

RE: Smeared?, posted on December 14, 2016 at 05:31:01
kyle
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 If I were starting an amp from scratch, I might not opt for a paralleled driver. If I were modding an existing amp, I would look at how much effort is is to change the the driver to something completely different. Also, I have a lot of tubes sitting around here that need a home and that could influence the choice. Starting with a blank page, I am liking the 6EJ7 recently. Nice little pentode that sounds good run as is or triode connected.
In the case of the offending 300B amp mentioned in this thread, it started with a 6SJ7 driver, which sucked, so I tried a variety of other octal tubes so I could use the same size socket.
I will say this, a paralleled driver sounds better to me than a cascade whether DC or cap coupled. The extra stage takes more away than the paralleled version adds.

 

RE: Nope ! Not allowed. Find the right tube, with correct mu and low plate resistance. (nt) , posted on December 14, 2016 at 08:37:56
drlowmu
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 Thanks, You ( and most others ) still assume I use half a 12AX7, as I did in the past. FYI, this can be done, and to a stellar effect, but the amp has to be engineered for the whimpy drive, in many areas. Conventionally trained engineers haven't the imagination to do this, and IT has to be perfect. Dennis Fraker has successfully done this, since 1989. No SET amp I know of, or YOU have ever heard, beats Dennis' implementations, or even comes close. Believe me !! He knows how to get what he wants, better than anyone I have seen or know of. Hands down.

Good news, I changed this in November 2016. Just as you have kindly suggested I do. Absolutely love the result. Thanks,

Jeff

 

yes. paralleled sections causing smear is fictional, posted on December 15, 2016 at 17:21:51
zarniwoop
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 It would be very easy to see if measured, as we can measure far lower time based discrepancies on modern test equipment. Two triode sections paralleled act as a uniform composite device even when not perfectly balanced with respect to current and gain. Look at the very well regarded RCA 2A3 as an example, the dual plates. Those are internally connected paralleled sections and they have no issues produced from that construction technique.

 

would like to see 'choir efect' measured..., posted on December 16, 2016 at 09:13:43
PakProtector
Audiophile

Posts: 12362
Joined: May 14, 2002
 as it is clearly a listenable affect. ( turn yer sarcasm meters off before reading this ). Perhaps *SOMETHING* is going on that is attributed to putting the two sections in ||...IDK, have seen no measurements ever.

What we have are 'opinions' based on no measureable proof. Then added on to this are aspersions cast on 'Engineers'...and often in the same post an EE PhD is then quoted...or at least his POV highly spoken of.

*LOVE* the Irony indeed.

On the 6SU7, this one is effectively a matched section-section 6SL7, IOW a very fine candidate for paralleling the two.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

try 'power' tubes, posted on December 16, 2016 at 09:20:29
PakProtector
Audiophile

Posts: 12362
Joined: May 14, 2002
 IME, the EL84 is a *VERY* fine signal tube. Very fine indeed...:) High ratio plate/g2 current. Good gm at low g2 voltages( around 100V ), and with a variable g2 voltage responds very well to tuning the tube characteristics to match a chosen plate load.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

RE: try 'power' tubes, posted on December 16, 2016 at 13:39:19
kyle
Audiophile

Posts: 1839
Location: London Ontario
Joined: September 29, 1999
 I agree. I first was made aware of the EL84 as a driver by an article by Thorsten Loesch. I just copied his version with a 300B and it absolutely is a great driver. It helps that I've got lots of them as well.

I would be very interested in how your latest amps are designed Douglas. You've had some great ideas in the past and I feel that they align with my view more often than not. I haven't done a PP amp for years but I'm thinking that I would like to apply some of the things I've learned to one now. The SE thing is a bit of a dead end for anyone that likes to listen to music at more than background volumes or that enjoys realistic bass. That should stir up the natives:)

 

RE: would like to see 'choir efect' measured..., posted on December 18, 2016 at 14:41:41
zarniwoop
Audiophile

Posts: 590
Location: NY
Joined: November 28, 2002
 I don't think it is a listenable effect. The paralleled sections act in unison in practice. The electrons don't know anything and the physical separation between the two devices is negligible as far as they're concerned.

I guess who would even bother to attempt to measure a potential effect? The time based delay wouldn't even be measurable on their equipment. If there is some kind of femtosecond delay or interaction is that even something to be concerned with for audio signals?

I'd love to see some measurements on a paralleled 6SU7 vs a mismatched paralleled 6SL7 and see if there is anything that shows an unexpected result. I'd imagine the linearity would be affected by one section running at a significantly lower current than the other, but any temporal effects should be insignificant.

 

You are incorrect., posted on December 22, 2016 at 06:52:33
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 On a good state of the art, or close to it high fi sytem, there is an audible difference between a single triode, and two paralleled.

In your example, a common NOS bi plate 2A3 will never match the sonics of a single plate 2A3, such as the original HARP 2A3, and the modern EML versions.

Of course, the original Harp 2A3, and the EMLs have symmetrical filament structures, and large emitting filaments, as does the modern JJ 2A3-40, so that is a very large advantage, over a " W" or "V" shaped filament in the standard NOS bi plate.

But people do hear differences, on better audio implementations, parallel versus a single triode. The only instrument that can detect it, is our ears.

No need to discuss Chinese manufacture 2A3s, they are not good enough. Maybe this " single triode in a bottle " is why people with high efficiency speakers like a 45 over a biplate 2A3. Again, "the" measuring device of-choice is a good hi fi, and the parts on either side of our cranium.

Have fun,

Jeff

 

RE: You are incorrect., posted on December 23, 2016 at 15:04:00
zarniwoop
Audiophile

Posts: 590
Location: NY
Joined: November 28, 2002
 I'm not going to debate a possible difference in sound between single triode tubes and paralleled section or paralleled separate tubes. People claim they hear all kinds of subtle differences between this that and the other thing.

I just object to calling the inferior sonic quality "smear". That implies some kind of time based latency across paralleled sections giving rise to the music signal that is different from a pure signal. This makes little sense if you know that the electrons involved in carrying the audio signals are moving close to the speed of light, and hence any time discrepancy from taking one different, but very very short path, is of no consequence to the, relatively, very slow audio signal that eventually is produced in your speakers or headphones. Some people tried to use the same logic with feedback loops and time smear was largely debunked as a source of the lesser quality.

I guess same thing with the filament structure. One might be better than an other, but its not due to a lack of time delay effect because of its symmetry.

 

RE: You are incorrect., posted on December 24, 2016 at 09:24:21
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Hey, you over simplified it, and your conclusions, theoretical, are bogus in practice. I do not mean to offend you in any way. Really !!

The ear can detect many things, and others will support my observations, it is smearing and it is a choir effect. Your "theory " and reasoning would be correct perhaps, if both tube sections were identical in spacing. They never are !!

1 plus 1 equals 2, not 1.

Jeff

 

RE: yes. paralleled sections causing smear is fictional, posted on January 4, 2017 at 03:37:35
PakProtector
Audiophile

Posts: 12362
Joined: May 14, 2002
 Zarni, by now you have been around here long enough that no physical proof will sway a religious fanatic. Take the stuff you may have read about Dennis Fraker's amps...specifically how some magical new term 'transfer efficiency' or some such dreck allows a 2.3641 Watt amp to run circles around more powerful amps in terms of delivered SPL. Makes no sense...and yet you hear it constantly, with no definition given to this new term...only, 'come hear it'.

Hopefully, belief in such things will result in the expected consequences...LOL
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

RE: try 'power' tubes, posted on January 17, 2017 at 11:54:09
PakProtector
Audiophile

Posts: 12362
Joined: May 14, 2002
 hey-Hey!!!,
Another liddle power tube I plan to examine is the 2E24. It is a DH number about the size of a 6V6 and given the performances of other DH tubes ought to work quite well.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

It was attempted in Glass audio many years ago by some people, posted on January 20, 2017 at 11:19:25
richardl
Audiophile

Posts: 3555
Joined: September 5, 2002
 They did not find the effect. I think that they were using output tubes. Lynn Olson was an author if I remember correctly.

 

phases are *NOT* split, posted on January 26, 2017 at 14:29:38
PakProtector
Audiophile

Posts: 12362
Joined: May 14, 2002
 their path evidently looks that way, hence the term, but 'split' is a misnomer. Cloned, anti-phase...and how good are the clones? since it is pretty evident that a lot of the various circuits sound different there has got to be some continuum.

However, one is not going to get the Pope to face Mecca and pray to Allah any more than a SE fan is going to believe PP works over a web forum post. It is rare even when presented with a real one...they're different. I will let y'all know as soon as I hear a SE amp I can tolerate/live with...LOL
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

have you guys looked at the harmonic distortion pattern change going from one to two tubes?, posted on February 2, 2017 at 01:15:29
morricab
Distributor or Rep

Posts: 9175
Location: switzerland
Joined: April 1, 2005
 I would guess that the "choir effect" and/or "smearing" has absolutely nothing to do with temporal effects...just not long enough distances or time delays. What might very well be changing though is the amount/type of harmonic distortion pattern that is being generated. Also, the size of the output transformer if it is not scaled accordingly for the paralleling of output tubes might mean saturation is worse for the paralleled output section and that makes new and less appealing distortions. All things being equal I would expect it to be inaudible but all things are likely not to be equal and therefore the distortion changes will impact the final sound...possibly inaudibly or possibly for the worse.

 

RE: have you guys looked at the harmonic distortion pattern change going from one to two tubes?, posted on February 3, 2017 at 05:18:35
cpotl
Audiophile

Posts: 1002
Location: Texas
Joined: December 6, 2009
 "I would guess that the "choir effect" and/or "smearing" has absolutely nothing to do with temporal effects...just not long enough distances or time delays."

Agreed. All kinds of things could be changed, leading in principle to audible differences, by putting a second tube in parallel; altered operating point, added input capacitance, change effective output impedance, etc., etc. But effects due to relative timing delays would not be one of them. Audio as far too low in frequency for that to be relevant.

Chris

 

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