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Jeffrey D. Medwin

What's the most linear tube?

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RE:  Type 45 ST TUBES :

 

When critically listening, ST 45s are not a linear tube, when playing a speaker.  It has a very shallow ( guessing 1/2 dB ) but broad mid-range suck out, and it fails to play the lower registers of a grand piano with proper dynamic power.  This is a tube problem of the ST 45 ( or globe , MANY of the early tubes ) and is not an amp or a speaker problem !! 

 

The ST45 was a cheaply-as-possible-made mass-produced tube, designed for early radios, not 15 inch woofers.  I have messed with 45s for 40 years !! 

 

It is easiest to detect the Type 45's tube deficiency, when using a speaker with a directly front - radiating 15 inch woofer  This becomes even more noticeable,  if the 15 inch woofer also employs a front-radiating horn.  A VOTT A7-8, which is what I happen to use,  is one example. 

 

modern-made EML 45 however,  likely ...........is a more linear Type 45,  much better made, decent,  but sadly, highly overpriced VS performance. 

 

I totally wasted two years of my audio life, ( and my money ) building two close to State Of The Art Direct Coupled two - stage Type 45 amps, in 2015 and 2016.  After all,  on line, " everyone" says the 45 tube beats a Type 2A3 !!   

 

My first DC 45 amp, totally destroyed a Yamomoto A-08 45 two stage amp, on a direct A-B, it was a major improvement over that A-08 in EVERY parameter.   Both these amps shared the best tube amp topology I know of,  ( simplest ) two stage and directly coupled.  But my amp had under 20 Ohm DCR  ( for chokes ), a LSES power supply, and good wiring, that the Yamomoto lacked.  The humongous performance difference between those two amps makes me chuckle, to this day !! 

 

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However,  my amp, with the ST 45, could never play a piano correctly, and it was the 45 ST TUBE's fault, not the amp or speaker. 

 

A $2.00 common 6AQ5 vacuum tube, designed for 1950's CAR radios, or a $5.00 GE 5-star 6005, a 6AQ5's military First Cousin, triode-connected, just "stomps all over" a Type 45 ST, as far as playing a speaker linearly and wide band, in a really good audio system.  I am VERY UPSET that I wasted those two years I hope, someone here, reading this, gains from my experience.  In all my reading on line, I have only found ONE other critique, similar to mine !!!   But ..... in two years, with two excellent amps, I know what I heard !!   And ..........right or wrong Jeff may be, ...................you ...........are fairly warned.

 

 

 

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LOOK, a round plate structure, symmetrical tube construction, and close spacing of all the elements.    Dated 6-1952.  A FIRECRACKER , great sonics.

 

 

 

                                                                                                                   - - - - - - - - - - - - - - - - 

 

In the 2A3 world, any of the biplates are only "just- average" in performance.  Avoid them. The ultra rare, earliest 2A3 Monoplate, with a HARP filament structure, are generally superior to the biplates that followed them.  Thank goodness, some of today's modern made monoplate 2A3s are now worthy of use, IF they use a symmetrical ( to the plate !!! ) HARP filament structure, and not a non-symmetrical  " Vee " or "W " filament structure . 

 

In 2020, a popular 2A3 choice, cost VS possible performance, would be a JJ 2A3- 40.  It has a single , beefy 300B plate ( 40 Watts ), a HARP filament structure, AND a highly advantageous 2.5 VAC filament, so it can be operated on better-sounding AC.  When a JJ 2A3 40 is conservatively operated at 10 Watts plate dissipation, it can be adjusted to sound fine and last long - such that your Grandchildren will also enjoy it immensely as they grow old.

 

Jeffrey Medwin 

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A triode strapped 6Y6 for $4 will get you 2A3 performance without all the fuss and bother.......

 

 

Maynard

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2 hours ago, Jeffrey D. Medwin said:

It has a single , beefy 300B plate ( 40 Watts ) and a HARP filament structure, AND a highly advantageous 2.5 VAC filament, so it can be operated on better-sounding AC. 

 

Sort of reminds me of the TJ voice of music globes I have. They have a 300B solid plate anode structure, with a 2.5 volt filament.

They had this lush sound about them...nice sounding. My only complaint is they didn't last very long with regard to emission.

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On 9/5/2020 at 12:40 PM, tube fanatic said:

A triode strapped 6Y6 for $4 will get you 2A3 performance without all the fuss and bother.......

 

 

Maynard

 

 

Hey Maynard, that is cool to know, and I believe you !!!   

 

My $37.90 ( on sale ) EH KT88, in 2019, beat out an amp with a super rare, expensive  VAIC AVVT Mesh Plate 2A3 for Finals.  That AVVT meshplate 2A3 is considered by some to be the best sounding 2A3 ever made !!  $1500 a pair, used. 

 

In caps, a WIMA DC LINK 4 Pin can beat out a Blackgate WKZ.

 

BTW Maynard, I am ripping that 2019 KT88 amp apart next week !!!!!!!    Its going to get rebuilt as two  monoblocks, same precise circuit ( except a 6FQ7 Driver ) , for my long term use !!!  Whenever I hear it playing,  just one channel, it creates the need for me to use it , enjoy it, that way, permanently.  I've shown you privately, how crowded that amp was in stereo, after we did all the needed bypassing in Montana 7-2019. 

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On 9/5/2020 at 12:56 PM, mike stehr said:

 

Sort of reminds me of the TJ voice of music globes I have. They have a 300B solid plate anode structure, with a 2.5 volt filament.

They had this lush sound about them...nice sounding. My only complaint is they didn't last very long with regard to emission.

 

Mike,

 

Q1 Did they happen to have a HARP-like filament also ??   

 

Q2 : What were you operating them at, plate voltage to cathode voltage, and current wise ??   

 

Me and my friends usually operate a 2A3 conservatively !!!  ( Even a JJ 2A3 40 with a 40 Watt pl;ate ) .  Typical " by the book " operation is 15 Watts dissipation, the rated maximum.  We do roughly 62% of that, and the tubes last "forever'". 

 

The amps also SOUND better, because (1) you are relieving the tube of a THERMAL stress, and (2) you have reduced the UNBALANCED DC CURRENTS that the SE output XFR has to process, by maybe 40 % less.  That translates sonically - into better highs and a quicker music presentation from the SE Output XFR, sorta FUN to hear !!

 

I now operate my personal amps ( 2019 KT88 SE , DC ) at only 23.5% of the tube's rated dissipation !! 

 

Jeff 

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2 hours ago, tube fanatic said:

A triode strapped 6Y6 for $4 will get you 2A3 performance without all the fuss and bother.......

 

 

Maynard

I can attest to that statement. I have a SE 6Y6 amplifier and it gives my SE 45 amplifier a run for it's money. Designed by one of my favorite designers on the web. Everyone should know where to find design and schematic.   👆

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No one interested in knowing who the designer of a wonderful sounding 6Y6 amplifier? Our own Maynard, calls it the "Little Sweetie." One of my favorite amplifiers. 

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21 hours ago, Jeffrey D. Medwin said:

Q1 Did they happen to have a HARP-like filament also ?? 

 

I'm pretty sure it's a "V" or "W" type filament structure.

 

21 hours ago, Jeffrey D. Medwin said:

Q2 : What were you operating them at, plate voltage to cathode voltage, and current wise ??   

 

Initially, the amplifier had the TJ tubes set-up at 2A3 spec, with regard to plate voltage and cathode/filament current/voltage.

Being specified as a 300B tube, we wanted to try it dialed up as a 300B.

The gentleman I bought the project from, scrounged up another PS transformer so we could get the higher plate voltage for 300B spec.

I used the amplifier like that for maybe a year.

But I then wanted to go back and convert the amplifier back to 2A3 specification, because I wanted to try different 2A3 tubes.

 

So I used the original PS xformer for lower plate voltage, and have used 2A3 since then.

 

The TJ tubes starting waning in emission after using them specced as 300B. Don't know why, they claim to be a 300B.

The tubes were run well within the plate voltage and cathode/filament current/voltage. 70% of total dissipation rating if I recall...

 

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I want to build a pair when I'm a bit more flush...

 

 

5 hours ago, henry4841 said:

No one interested in knowing who the designer of a wonderful sounding 6Y6 amplifier?

 

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Q1 Did they happen to have a HARP-like filament also ?? 

 

I'm pretty sure it's a "V" or "W" type filament structure.

 

Dear Mike,

 

In a DHT tube, the cathode IS the filament, and TJ design engineers short-changed their own design, by using a V or W filament. 

 

A HARP filament is usually 8 strings of filament, sometimes more, so it has a LARGE cathode surface area to power the tube  Importantly, the larger harp filament is ALSO far more symmetrically positioned, to the tube's plate !!! 

 

There is no substitute for symmetry in a tube's design.   Perfect tubes would have a round plate and cathode ( 7B4, Eimac T-35 ) .

 

Try to borrow a pair of JJ 2A3-40s from a good friend for a week, and just give them a listen.  They have a harp filament. 

 

Conservative operation, 10.5 Watts DISS., of their 40 Watt plate, is sweet, relaxed sounding  250 P-K, 0.042 A. , and it is easier for the SE OPT. XFR. .   I enjoy and prefer hearing 2A3 amps - at that op point.    With 2A3s, my Magnequest  DS-025 gets better highs and a faster speed of music-delivery at 42 mills, with the slight trade-off expense of " meat on de bone ".   

 

Same applies to my personal-use  2019 E.H. KT88  SE amp.  It is running at 23.5% of Maximum Plate dissipation through - again , a MQ  DS-025 .  ( 9.95 Watts Dissipation of a KT88's 42 Watt rated plate, 42.3 mA. times 235.1 VDC P-K ). 

 

I suppose, it would be appropriate to say this : when we draw a certain amount of current through a SE output tube, we are not only hearing the output tube, but also, HOW the SE Output Transformer reacts when having more, or less, current drawn through it.   They are intimate, to each other !! 

 

This is analogous to people who blindly roll front end tubes in a tube amp. We are NOT just hearing the Vacuum Tube you swapped in place, but also the front tend tube's PLATE RESISTOR, which, with the tube, makes up the signal.   

 

Often one can gain a far greater PERMANENT sonic performance advantage, ( perhaps for far less cost ), by also upgrading the QUALITY of the amp's existing plate resistor, Ra.    They all do sound different I find, JUST LIKE tubes !!    Ditto for the vacuum tube's cathode resistor, Rk. 

 

Best wishes.

 

Jeff

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This is so wrong on so many levels I don't even know where to start. There is either a speakers or amp design problem. There ain't no mid suck out on a 45 triode.

 

Thomas Mayers comments on the 45 are spot on.

http://vinylsavor.blogspot.com/2011/09/tube-of-month-45.html 

 

His comments on defective 45s may be of interest but alas this is true of all early similar triodes 45 50 and more examples.

 

 

 

 

 

 

 

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29 minutes ago, seti said:

This is so wrong on so many levels I don't even know where to start. There is either a speakers or amp design problem. There ain't no mid suck out on a 45 triode.

 

Thomas Mayers comments on the 45 are spot on.

http://vinylsavor.blogspot.com/2011/09/tube-of-month-45.html 

 

His comments on defective 45s may be of interest but alas this is true of all early similar triodes 45 50 and more examples.

 

 

 

 

 

 

 

 

But Seti, he can hear it. 

 

Wait, he did not say if that occurred with every 45 based amp he has heard, or that he tried different 45s in different amps and they all have a suck out. 

 

What is the most linear tube?

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2 minutes ago, dwilawyer said:

 

But Seti, he can hear it. 

 

Wait, he did not say if that occurred with every 45 based amp he has heard, or that he tried different 45s in different amps and they all have a suck out. 

 

What is the most linear tube?

 

True... Any tube can have defects leading to any manner of issues.

 

I can tell you after I get a Tektronix tube curve tracer 8-)

 

 

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5 minutes ago, seti said:

 

True... Any tube can have defects leading to any manner of issues.

 

I can tell you after I get a Tektronix tube curve tracer 8-)

 

 

I should of put a wink. Some people can hear a lot of things. Cable lengths, resistors in parallel, tube suck outs.

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The suck out in the middle midrange is minor, very very shallow, but it is rather a wide one. 

 

You tell me you have not heard any of these ST anomalies, and I fully understand where you are coming from, believe me.  WHY ?   Because there is both a speaker and an amplifier problem, and it is in your house, not mine !!  I wrote to you and explained it clearly.   

 

You need,  must have,  ( as I have explained above, and to you in a P.M. today ) a good front-radiating 15 inch driver, preferably straight front-horn loaded, to play back a grand piano properly.   You also lack, and need to listen to,  a really good set of amps, that the Germans don't yet, to my knowledge, make.  You are relying upon magazines, as I first did , and that is just not going to get any person the absolute truth !!!     

 

There is no substitute I know of, for someone's direct experience. I have directly paid the price Seti, done my homework, and I personally learned the answer on ST 45s, several years ago.  I was hoarding about fifty ST45 tubes, some globes,  and I sold every single one of them on eBay a few years ago.  I loved selling each one.   I didn't sell a single GE 5 star 6005.   It is a firecracker of a tube. 

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49 minutes ago, Jeffrey D. Medwin said:

There is no substitute I know of, for someone's direct experience. I have directly paid the price Seti, done my homework, and I personally learned the answer on ST 45s, several years ago.  I was hoarding about fifty ST45 tubes, some globes,  and I sold every single one of them on eBay a few years ago.  I loved selling each one.   I didn't sell a single GE 5 star 6005.   It is a firecracker of a tube. 

 

SETI doesn't have a speaker problem. He's got awesome speakers. But now you are mixing 15" front radiators being necessary with a "broad midrange" suckout which I don't understand. 

 

SETI, you have German AMPS?

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Having the birds that fly in a different direction blocked I have missed out on some of the post. I much prefer to listen to certified worldwide renown designers and sellers of tube gear like vinynalsavor. I built one of his designs years ago and was well pleased with the sound. Top designer and reviewer. Been following what he has to say for years. Everyone is to follow whoever they want to believe. I fly with the flock unless the birds that fly on a different course are geniuses with spectacular hearing. I look for those on technical forums and not on social media ones. 

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Well my 45 amp with EML ST tubes sounds absolutely fantastic, most linear sounding? according to whom? One person I kind of doubt it.... To each his own....

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One does not have to take someone's word on which tube is the most linear if you can read tube charts. The 300B has the most linear curves and the 45 is not far behind. Notice how well the curves are spaced apart and how the different curves taper off on the 300B. That is what you look for when talking about most linear tube. Fantastic looking if one is into such. It's all about the curves. 

 

https://frank.pocnet.net/sheets/084/3/300B.pdf   page 3. 

 

https://frank.pocnet.net/sheets/127/4/45.pdf  page 3

 

These are what designers look at when choosing a tube for a circuit. Same goes for an transistor. Look at the data sheets or if able test for yourself. Anyone who says different is to be ignored. 

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10 hours ago, Jeffrey D. Medwin said:

There is no substitute I know of, for someone's direct experience. I have directly paid the price Seti, done my homework, and I personally learned the answer on ST 45s, several years ago.  I was hoarding about fifty ST45 tubes, some globes,  and I sold every single one of them on eBay a few years ago.  I loved selling each one.   I didn't sell a single GE 5 star 6005.   It is a firecracker of a tube. 

 

No offense I just think you did the wrong homework for the wrong class. I've done lots of testing of 45s and my speakers. I've lived with them for 15 years...  It doesn't mach up with many builders and not just me. Do you think Gordon Rankin or Thomas Mayer would spend so many years on the 45 if it had a suck out? The suck out is a sympton of a defective tube or amp or speakers. When I get my hands on a curve tracer I'll go through every 45 I have.  

 

 

 

 

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