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New Production Tung Sol 6550, Penta KT88s [message #96284]

Wed, 18 January 2023 23:01

positron
Messages: 113
Registered: May 2020

Viscount

My first question is, what do you think of the general sonic quality
of these two tubes. Does each have a sonic reputation?
Try to be as specific as possible with any response.

Thanks and cheers

pos

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Re: New Production Tung Sol 6550, Penta KT88s [message #96292 is a reply to message #96284]

Sat, 21 January 2023 18:24

positron
Messages: 113
Registered: May 2020

Viscount

Evidently no one uses them?

My testing has found both tubes to be rather thin, anemic sounding compared to JJs and Winged Cs.

So I demagetized both, using my 100 watt soldering gun magnetic field (gun windings), and both tubes became fuller than the JJs and Winged Cs. Quite a sonic change. The new Pentas just slightly fuller than the new Tung Sols.

When the tubes are manufactured, induction heating of the plate removes gases. Evidently, the switch/field is simply flipped, rather than gradual field removal.

So when one purchases a new output tube, what you purchase and hear is not necessarily what the tube sounds like after being demagnetized.

One could probably use a dryer, a motor, anything that produces an AC magnetic field. Simply rotate each tube around the AC device field, and then gradually distance the tube from close to 3 feet or more from the device, and power off the device.

cheers

pos

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Re: New Production Tung Sol 6550, Penta KT88s [message #96295 is a reply to message #96292]

Sat, 21 January 2023 20:48

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

Who'da thunk it?

Degaussing a tube! Interesting observation!

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Re: New Production Tung Sol 6550, Penta KT88s [message #96296 is a reply to message #96295]

Sat, 21 January 2023 21:33

positron
Messages: 113
Registered: May 2020

Viscount

Neither tube initially sounded very good at all in my system Wayne.
But I have performed this trick before, so I degaussed both and the
sound sure improved. The zingy highs, the thin sound are no longer.

Best guess of the top of my head is it creates random molecular orientations.? I would have to delve more deeply with a
physics/chemistry expert.

Caveat: My system was a lab system (now in my apartment) is
extremely sensitive. The sound is also not sterile, but very natural.

There are multiple tweaks that I can perform to cross check and
see if the sensitivity results match.

One is being able to alter a crossover resistor by 1/1,000,000 of an
ohm with timber, sound stage change etc heard.

Another is, for each speaker leg, I use ten 18 gauge wires in parallel, 6 feet long. If I change to 9 or 11 wires in one leg, the timber, sound stage changes etc.

Audiophile Dan comes over (50 mi) so we have opportunities to make changes
and decide if a tweak is an improvement or detriment.

Cheers

pos

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Re: New Production Tung Sol 6550, Penta KT88s [message #96297 is a reply to message #96296]

Sun, 22 January 2023 17:28

positron
Messages: 113
Registered: May 2020

Viscount

Another tidbit is the frequency response change of 1/1,000,000 equates to
-114 to -120db down from the fundamental (one to one on the steepest part of the signal slope).

Even though small, the change covers octaves of bandwidth. Rane Corp found a change covering 1/3rd octave or less is generally not perceived.

A spec of +/- 0,1db equates a change of only about -54db. Not surprising to me that we notice sonic differences of different manufacturer's components even though the frequency response are the same, +/- 0,1db 20 to 20khz.

Cheers

pos

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Re: New Production Tung Sol 6550, Penta KT88s [message #96301 is a reply to message #96297]

Mon, 23 January 2023 20:25

gofar99
Messages: 1949
Registered: May 2010
Location: Southern Arizona

Illuminati (5th Degree)

Hi, something I would not have guessed. I agree that really small changes in components can make a difference. 0.1db of the wrong stuff in the wrong place can really mess up a good design. The saving grace if you want to call it that is the speaker and if you use a turntable the cartridge errors are far worse and will mask a lot of ones internal to the electronics.

Good Listening
Bruce

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Re: Demagnetizing Tung Sol 6550, Penta KT88s [message #96302 is a reply to message #96301]

Mon, 23 January 2023 22:12

positron
Messages: 113
Registered: May 2020

Viscount

gofar99 wrote on Mon, 23 January 2023 20:25

Hi, something I would not have guessed. I agree that really small changes in components can make a difference. 0.1db of the wrong stuff in the wrong place can really mess up a good design. The saving grace if you want to call it that is the speaker and if you use a turntable the cartridge errors are far worse and will mask a lot of ones internal to the electronics.

Hi Bruce,

Over the years, the sensitivity of the ear has certainly surprised me
as well.

What is just as surprising to me is that the electronic designs/parts
heavily influence as well. Consider that I am using a two way speaker
to perceive sonic differences to astonishing low levels.

This is a long lab experiment for me,

1. to find out just how sensitive one's ear is,
2. that some electronics designs (and parts available) are better than
others. Finding the best design, and parts.
3. what is possible, just how accurate to the source can the
electronics be under the best conditions.

Just trying to help out in the electronics as Wayne
is doing with his excellent speaker designs.

Back to the topic at hand. I believe the new production Tung Sols and Pentas
can be used to good effect if the plates are demagnetized. Otherwise, I did not like either.

Cheers

pos

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Re: Demagnetizing Tung Sol 6550, Penta KT88s [message #96412 is a reply to message #96302]

Tue, 21 February 2023 22:45

positron
Messages: 113
Registered: May 2020

Viscount

After more testing/auditioning, I prefer the Pentas over the
Tung Sols. I find the new Tung Sols are still zingy in the highs.
The Pentas are just slightly fuller compared to the Tung Sols.

That is it for now.

Cheers

pos

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Re: Demagnetizing Tung Sol 6550, Penta KT88s [message #96526 is a reply to message #96302]

Thu, 16 March 2023 15:30

positron
Messages: 113
Registered: May 2020

Viscount

Well, more testing between the new tong sols and Pentas, the
tung sols still have a little too much zing in the highs.

However, the Pentas do sound wonderful now. A little less bass
and the highs still do not zing imo. When playing time after time,
the guitar always sounded a little too full with the JJs, but the
Pentas seem to do the job nicely. It may be my favorite KT88 besides
the original Winged Cs from St Pete.

Have not tried the Psvanes, Treasures etc and the expensive ones from
Europe.

cheers

pos

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Re: Demagnetizing Tung Sol 6550, Penta KT88s [message #96527 is a reply to message #96526]

Thu, 16 March 2023 21:28

gofar99
Messages: 1949
Registered: May 2010
Location: Southern Arizona

Illuminati (5th Degree)

Hi, A diyer of some of my projects reported issues a while back (4-5 years) with Psvane KT88s. They were not thermally stable and were unable to dissipate anywhere near the ratings for a KT88. This parameter is vip in the amps I design as they run class A. He reported that they would only handle about 50% of the rating before serious red plating began. He had them replace several set and all did the same thing... They may be OK now but I have no way of knowing.

Good Listening
Bruce

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