I have already decided to get a quad of KT77s for my Yaqin MS-20L, which is an EL34 based integrated amp. I have heard good things about the Gold Lion sound but not the reliability. The JJ are about 1/3 the price of Gold Lions.
Has anyone here heard or used both?
I am leaning toward the JJ as I suspect the law of diminishing returns will come into play.
thanks
Has anyone here heard or used both?
I am leaning toward the JJ as I suspect the law of diminishing returns will come into play.
thanks
My amp has adjustable bias and I also used to be an electronics tech back in the tubes days. So that won't be a problem.
It is looking like I will be giving the JJs a try and see how it goes.
6L6 is a beam tube like the KT77.
EL34 is a true pentode with similar pinout.
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All of JJ's Octal production is, at best, highly inconsistent.Outright garbage has been marketed in North America.
I strongly suggest that "reissue" Gold Lion tubes sourced from a vendor known to do things correctly be purchased. IMO, this is not a time to "cheap out".
I've used lots of JJ octal tubes and never had a reliability problem with them. Many have been bought through Mesa, so Mesa may test them more thoroughly... I even made a 100 watt guitar amp with a pair of JJ KT88s that runs them with a plate voltage of 760v and the tubes just keep on running, happy as can be in that amp.
Like you said I think it's a consistency or QC problem.
KT 77s are beam (not bean LoL) tetrodes, cleverly designed to have characteristics very similar to EL34s, and have often been used as drop-in replacements. Of course, bias should be adjusted. 6L6s have quite different characteristics from both of them, as well as from their near cousins, the KT66s. Likewise 7189s are also beam tetrodes designed to mimic EL84s.
To understand the story behind all this mimicry, we need to understand that Phillips held the patents for the power pentode, while RCA and Genelec/M-OV jointly held the patents for the beam tetrode, and neither wanted to pay patent royalties to the other. So the RCA/Genelec camp would produce tetrodes that mimic'ed popular power pentodes. IIRC Phillips also developed the power pentode to avoid paying beam tetrode royalties to RCA/Genelec.
Sent from my phone. Please excuse any typpos.
All the 7189's and 7187A I have had all had three sets of grid posts, and the suppressor grid wound around the outboard set.
cheers,
Douglas
I once used octets of Groove Tubes E34Ls made by JJ and later I used JJ KT77s. Both were unreliable, either noisy, or internal short that damaged my amps on two occasions. Twice because the GT E34Ls were the best sounding tube of this type I've ever heard, so whenever they blew up I replaced them over and over, but the whole batch was bad so I gave up on them. Maybe now, 10 years later they are good again? I will never buy a JJ tube again. Even 12AT7 gold pin JJs were noisy. Every JJ tube I've had had problems.
Now I only buy Black Treasure or New Sensor tubes because they are reliable, and life is too short for broken tube amps. I use Gold Lion KT88s now, they sound awesome. I had one shorted with a clinking sound inside it, but my excellent tube vendor Jim McShane took care of me under warranty.
Now I only buy Black Treasure or New Sensor tubes because they are reliable, and life is too short for broken tube amps. I use Gold Lion KT88s now, they sound awesome. I had one shorted with a clinking sound inside it, but my excellent tube vendor Jim McShane took care of me under warranty.
I already said it here, I've had a JJ's KT-88 quad in my Luxman for a 1.5 year, they sound tremendous, no noise, what-so-ever other trouble.
All this time run daily for several hours, sometimes on weekends from dawn to dusk - always satisfying.
Well built and look undestructable. Extremely stable - adjusted bias a year ago, just checked, no need to reach for a screwdriver.
I will certainly buy these if it needs. Some people have bad luck, some are. .. just being cheap with getting stuff from sheitty sources.
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The KT77 Suppressor Grid is internally connected to the Cathode.
Pin 1 is not connected to the tube (NC).
The 6CA7 and EL34 Suppressor Grid is Not connected to the Cathode.
The Suppressor Grid is connected to Pin 1.
These are the only Popular Power Tubes that I am aware of that have the suppressor grid brought out to a separate pin. You may find others.
The transconductance of the 6CA7, EL34, and KT77 are very similar.
The transconductance of the 6L6, KT66 are not similar to the KT77.
The same pinout does not necessarily make the tubes the same.
I have tube rolled some of my amps to use 6L6, KT66, EL34 (connect pin 1), KT88 and
KT77. Watch the maximum ratings of the tubes. Set your bias accordingly.
I do use them conservatively.
The filaments range from 0.9A to 1.6A, another consideration when tube rolling.
Know all about your amplifier before you tube roll.
Pin 1 is not connected to the tube (NC).
The 6CA7 and EL34 Suppressor Grid is Not connected to the Cathode.
The Suppressor Grid is connected to Pin 1.
These are the only Popular Power Tubes that I am aware of that have the suppressor grid brought out to a separate pin. You may find others.
The transconductance of the 6CA7, EL34, and KT77 are very similar.
The transconductance of the 6L6, KT66 are not similar to the KT77.
The same pinout does not necessarily make the tubes the same.
I have tube rolled some of my amps to use 6L6, KT66, EL34 (connect pin 1), KT88 and
KT77. Watch the maximum ratings of the tubes. Set your bias accordingly.
I do use them conservatively.
The filaments range from 0.9A to 1.6A, another consideration when tube rolling.
Know all about your amplifier before you tube roll.
Sounds like those may have been made by Philips/Mullard/Sylvania (and sometimes relabelled by RCA and Tung-Sol)- ie basically ruggedized EL84s. I have also come across true7189s with beam plates.
Truer word were never said!
Yeah, and this just started because I asked about which KT77 people preferred...
BTW I ordered a quad of Gold Lions.
Cyto,
It would have been nice if you had listed the operating Voltages of your Cathode, Control Grid, Screen Grid, and Plate, as well as the Cathode Current of your Yaqin MS-20L with its EL34s in place. Yes, the KT77 and EL34 specs are similar, but it would have been nice to know the quiescent operating state of the tubes.
Sometimes, a particular manufacturer of tubes gets a bad name, because the tube was operated beyond its maximum ratings.
And over the years, some of the current manufacturers have improved their reliability.
In very recent years, I have purchased nothing but JJ tubes from Eurotubes (.com).
I have not had any problems with them. KT77, KT66, KT88, 6L6GC, and 2A3.
Eurotubes goes through an elaborate series of tests for the JJ tubes that they sell.
I like the sound of those JJ tubes, and since they are reliable, I will continue to purchase them there. My amplifiers are all of my design, and I use the tubes below their maximum ratings.
I sometimes think about purchasing 'boutique' tubes, but I do not find the price to be justified. Maybe I should try just one pair, and do a comparison.
It would have been nice if you had listed the operating Voltages of your Cathode, Control Grid, Screen Grid, and Plate, as well as the Cathode Current of your Yaqin MS-20L with its EL34s in place. Yes, the KT77 and EL34 specs are similar, but it would have been nice to know the quiescent operating state of the tubes.
Sometimes, a particular manufacturer of tubes gets a bad name, because the tube was operated beyond its maximum ratings.
And over the years, some of the current manufacturers have improved their reliability.
In very recent years, I have purchased nothing but JJ tubes from Eurotubes (.com).
I have not had any problems with them. KT77, KT66, KT88, 6L6GC, and 2A3.
Eurotubes goes through an elaborate series of tests for the JJ tubes that they sell.
I like the sound of those JJ tubes, and since they are reliable, I will continue to purchase them there. My amplifiers are all of my design, and I use the tubes below their maximum ratings.
I sometimes think about purchasing 'boutique' tubes, but I do not find the price to be justified. Maybe I should try just one pair, and do a comparison.
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