This may be out of place here. If so, I apologize.
I've only owned one tube amp and quite new to this.
Basically the question is should I spend more money on output tubes or would I benefit by getting a more powerful rectifier - if I am phrasing that correctly?
I've had my ST120 for a couple years and wildly pleased with it.
The other day I had a 6550WE red plate. After a bit of reading it appears I need to replace the 10ohm 2w resistor and I intend to replace the one bad tube with four new ones because, WHY NOT?
I have never "tube rolled" so I am going to lean on the greater knowledge of this group.
I imagine speakers and music should be considered when "rolling tubes"? It's all a sonic relationship.
My system
Preamp: NAD C658 running Dirac Live
Speakers: Goldenear Triton Five
Subs: 12" sealed cabinets x2 powered by a Peavey CS800x (temporary power)
Music: Mostly Tidal via Roon though have Pioneer Elite PD-65 cd player and an AT LP120 turntable.
Artists: Tord Gustavsen Trio, Pink Floyd, Taylor Swift, Nora Jones, Lyle Lovett, Aurora, Beck - if it has imaging for days and sonically interesting, I'll listen to it.
What are my goals: IMAGING & TONAL BALANCE.
I've spent years and years trying to setup a system that is balanced and the speakers disappear in the room. I finally have it; Tord Gustavsen Trio are 10' through the wall, Yello's Planet Da Da (flamboyant mix) has sound seemingly coming from behind me, and that low bass in Boz Skaggs "Thanks to you" rumbles my underside.
As of now the ST120 is delivering very little bass due to the 70hz crossover I set by Dirac to integrate my subs. I have, at times, disabled the subs and driven the Tritons full range but only for a few minutes at a time. The bass output is impressive, the speakers and amp, but I have not done so at length.
In the future, however, with "Dirac Live with Bass Control" I'll have the option of delivering full range to the Triton Five's and Dirac will integrate the subs seamlessly. So, in the future the ST120 will be delivering full range output.
I could swing a set of GL KT88's, or a set of 6550WE's and a GZ33 without much concern but, I'm not sure what the benefits of either decision would be? I'm not even sure how a rectifier can affect the sound - from what I gather it has to do with headroom.
I plan on ordering parts on Tuesday, hopefully I will have some help from you folks by then.
I've only owned one tube amp and quite new to this.
Basically the question is should I spend more money on output tubes or would I benefit by getting a more powerful rectifier - if I am phrasing that correctly?
I've had my ST120 for a couple years and wildly pleased with it.
The other day I had a 6550WE red plate. After a bit of reading it appears I need to replace the 10ohm 2w resistor and I intend to replace the one bad tube with four new ones because, WHY NOT?
I have never "tube rolled" so I am going to lean on the greater knowledge of this group.
I imagine speakers and music should be considered when "rolling tubes"? It's all a sonic relationship.
My system
Preamp: NAD C658 running Dirac Live
Speakers: Goldenear Triton Five
Subs: 12" sealed cabinets x2 powered by a Peavey CS800x (temporary power)
Music: Mostly Tidal via Roon though have Pioneer Elite PD-65 cd player and an AT LP120 turntable.
Artists: Tord Gustavsen Trio, Pink Floyd, Taylor Swift, Nora Jones, Lyle Lovett, Aurora, Beck - if it has imaging for days and sonically interesting, I'll listen to it.
What are my goals: IMAGING & TONAL BALANCE.
I've spent years and years trying to setup a system that is balanced and the speakers disappear in the room. I finally have it; Tord Gustavsen Trio are 10' through the wall, Yello's Planet Da Da (flamboyant mix) has sound seemingly coming from behind me, and that low bass in Boz Skaggs "Thanks to you" rumbles my underside.
As of now the ST120 is delivering very little bass due to the 70hz crossover I set by Dirac to integrate my subs. I have, at times, disabled the subs and driven the Tritons full range but only for a few minutes at a time. The bass output is impressive, the speakers and amp, but I have not done so at length.
In the future, however, with "Dirac Live with Bass Control" I'll have the option of delivering full range to the Triton Five's and Dirac will integrate the subs seamlessly. So, in the future the ST120 will be delivering full range output.
I could swing a set of GL KT88's, or a set of 6550WE's and a GZ33 without much concern but, I'm not sure what the benefits of either decision would be? I'm not even sure how a rectifier can affect the sound - from what I gather it has to do with headroom.
I plan on ordering parts on Tuesday, hopefully I will have some help from you folks by then.
Go for KT120, you won't be disappointed since that amp should be able to work with KT120. You can email Bob Latino to ask him for in his forum.
I just upgraded my KT88 to KT120, I can't explain the sound. It's just totally different from KT88. Don't waste your money for KT88, doesn't cost much for KT120. I was thinking to go for shuguang black treasure kt88-z or Psvane KT88-T Classic MKII II but the price are similar so I go for KT120 in case I can swap later with other amps.
Mine upgrade:
-JJ 12AX7/ECC83
-ELECTRO-HARMONIX 6SN7
-Tung-Sol KT120
KT88 blows both top and bottom but more bright at the bottm while KT120 blow on top only. Maybe just my amp or something.
I just upgraded my KT88 to KT120, I can't explain the sound. It's just totally different from KT88. Don't waste your money for KT88, doesn't cost much for KT120. I was thinking to go for shuguang black treasure kt88-z or Psvane KT88-T Classic MKII II but the price are similar so I go for KT120 in case I can swap later with other amps.
Mine upgrade:
-JJ 12AX7/ECC83
-ELECTRO-HARMONIX 6SN7
-Tung-Sol KT120
KT88 blows both top and bottom but more bright at the bottm while KT120 blow on top only. Maybe just my amp or something.
Attachments
lion kt88 is good too but if the amp can support KT120, it's better go for KT120 instead, otherwise; you would spend more later.
KT120 is less linear and also demands as low grid resistor as 6550 ( 51k )
KT88 is (in my opinion) a better choice.
KT88 is (in my opinion) a better choice.
Your valve amplifier is red plating after only 2 years ownership!
That's a Red Flag for me.
Look to your circuit topology and implementation before even contemplating a change....
Is it out of warranty?
Send it back to manufacturer!!
That's a Red Flag for me.
Look to your circuit topology and implementation before even contemplating a change....
Is it out of warranty?
Send it back to manufacturer!!
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It's no problem with the amp, it's a problem with selection of tubes.
6550 needs a lesser grid resistor then present in this amp, it might work
for a while but any tendency for grid current will cause a tube to go out of
control. It's simply a matter of use outside tube limits.
KT88 will fit just fine here.
But this is not for the end user to address surely.
It's a manufacturer issue ....what an expensive.....
Indeed I'm sure they ...the manufacturer....would carry out any repairs without quibble.
It's a manufacturer issue ....what an expensive.....
Indeed I'm sure they ...the manufacturer....would carry out any repairs without quibble.
There is no repairs needed, just a replacement of tubes.
Tubes are like light bulbs with a finite life. And if mis-used they will have
a shorter life.
Unfortunately a lot of misinformed people recommends tubes that is unsuitable
and will have a shorter life.
I am the manufacturer; I built it from a kit provided by Tubes4hifi.
I suspect the issue was due to over voltage - greater that 135v - sent to the amp via a variac. I believe a friends child turned i the knob when they were visiting and I had not noticed; but I cannot say with 100% certainty.
When the replate happened I immediate turned it all the way down but it seemed in the wrong place to me.
Anyway, I accept this has happened.
Could be the tube or the voltage? I don't know.
I do know I have to replace the single bad tube, better to replace both tubes on that channel. I am looking at this as an opportunity to possibly try something different altogether.
I know from the forum support this amp many people are running EL34, 6550WE, KT88, KT120, and I believe a saw a person running KT150's.
With complete confidence I can say the 6550WE, KT88, and KT120 will run just fine.
I suspect the issue was due to over voltage - greater that 135v - sent to the amp via a variac. I believe a friends child turned i the knob when they were visiting and I had not noticed; but I cannot say with 100% certainty.
When the replate happened I immediate turned it all the way down but it seemed in the wrong place to me.
Anyway, I accept this has happened.
Could be the tube or the voltage? I don't know.
I do know I have to replace the single bad tube, better to replace both tubes on that channel. I am looking at this as an opportunity to possibly try something different altogether.
I know from the forum support this amp many people are running EL34, 6550WE, KT88, KT120, and I believe a saw a person running KT150's.
With complete confidence I can say the 6550WE, KT88, and KT120 will run just fine.
Not all engineering designs are without flaws.
Automobiles and Trucks have recalls.
A bad or faulty design that is a safety hazard, is required to be recalled and fixed by 2 groups:
The US Government
The Manufacturer's Lawyers.
Very few amplifiers have recalls.
Your insurance company's Lawyer will step in, if your house burns down.
If only the amp is destroyed, it generally is not worth it to anybody to hire a lawyer.
Tubes have conservative ratings.
Various tubes of the same registered part number vary in their ability to exceed their ratings.
Your Mileage May Vary.
Various tube types have different ratings for Maximum Rg, versus fixed bias, self bias, and total Plate + Screen Dissipation.
Violate at your own risk.
Various tube types present a different current draw from the power transformers 6.3V filament windings.
Some power transformers are more conservatively rated than others.
Violate at your own risk.
I see many violations of these ratings on schematics on this forum.
And I see even more violations of these ratings on other schematics that appear elsewhere on the web.
Caveat Emptor ("Buyer" beware).
Just My Opinions
Automobiles and Trucks have recalls.
A bad or faulty design that is a safety hazard, is required to be recalled and fixed by 2 groups:
The US Government
The Manufacturer's Lawyers.
Very few amplifiers have recalls.
Your insurance company's Lawyer will step in, if your house burns down.
If only the amp is destroyed, it generally is not worth it to anybody to hire a lawyer.
Tubes have conservative ratings.
Various tubes of the same registered part number vary in their ability to exceed their ratings.
Your Mileage May Vary.
Various tube types have different ratings for Maximum Rg, versus fixed bias, self bias, and total Plate + Screen Dissipation.
Violate at your own risk.
Various tube types present a different current draw from the power transformers 6.3V filament windings.
Some power transformers are more conservatively rated than others.
Violate at your own risk.
I see many violations of these ratings on schematics on this forum.
And I see even more violations of these ratings on other schematics that appear elsewhere on the web.
Caveat Emptor ("Buyer" beware).
Just My Opinions
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It's best to go tubes4hifi forum or email Bob for trouble-shooting and asking if it's support KT120. I am sure he will answer your questions.
First, I did not come here asking if it supports KT120 tubes.
Second, I know it will support 6550WE and KT88 tubes, which is what I did come here asking about.
Third, my question has NOTHING to do with supporting the tubes, it was about sonic qualities of the 6550WE and GL KT88 tubes with my setup.
Was this a foolish question, maybe.
I thought I have a similar PP 60w amp so I share my experience KT88 and KT120 with you. If you don't like it, then sorry.
Good luck.
Good luck.
“PP” 60w amp.
Not sure what PP means?
Was not trying to be a jerk. Frustrating when a question gets derailed and becomes something I never asked.
I apologize.
Not sure what PP means?
Was not trying to be a jerk. Frustrating when a question gets derailed and becomes something I never asked.
I apologize.
I am sorry, I should have focused on the Variac causing a problem.
In Post # 10, we see the cause of the Red Plating of the tube(s) . . .
A Variac that was turned up to 135V.
That might have been nice to know right up front, in Post # 1.
If by any chance, the average of your power mains rms volts is different than the voltage rating of your amplifier,
Then I suggest using either a Buck Transformer, or a Boost transformer to run the amp from, instead of using a Variac.
Common transformers that can be used as either Buck or Boost are available in 2.5V, 5V, 6.3V, 12.6V, etc.
I am sure there are many on this forum who can tell you how to set up a Buck or a Boost transformer.
My amplifiers all run OK off of power mains that vary from 117V to 123V, which my power mains do, depending on the time of day, and which of the four seasons.
I adjust the amplifier power supplies and bias so that the amplifier voltages are exactly on with the mains voltage at the center value of my power mains, which is 120V.
PP stands for Push Pull.
Unfortunately, our world insists on abbreviating by using 2 and 3 letter Acronyms.
It is a form of lazy writing.
When is a FLA not a 3 letter Acronym?
When it is a Four Letter Acronym (FLA). Etc.
In Post # 10, we see the cause of the Red Plating of the tube(s) . . .
A Variac that was turned up to 135V.
That might have been nice to know right up front, in Post # 1.
If by any chance, the average of your power mains rms volts is different than the voltage rating of your amplifier,
Then I suggest using either a Buck Transformer, or a Boost transformer to run the amp from, instead of using a Variac.
Common transformers that can be used as either Buck or Boost are available in 2.5V, 5V, 6.3V, 12.6V, etc.
I am sure there are many on this forum who can tell you how to set up a Buck or a Boost transformer.
My amplifiers all run OK off of power mains that vary from 117V to 123V, which my power mains do, depending on the time of day, and which of the four seasons.
I adjust the amplifier power supplies and bias so that the amplifier voltages are exactly on with the mains voltage at the center value of my power mains, which is 120V.
PP stands for Push Pull.
Unfortunately, our world insists on abbreviating by using 2 and 3 letter Acronyms.
It is a form of lazy writing.
When is a FLA not a 3 letter Acronym?
When it is a Four Letter Acronym (FLA). Etc.
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My power gets up to 127v at times.
We have no children so using a vardiac is a non-issue as I'm the only one who would ever adjust it. Obviously, need to check it after children come around 2-3 times a year.
I thought it was implied I knew the cause from my first post.
Ultimately my post was asking about KT88 v 6550WE and nothing about why the tube red plated.
We have no children so using a vardiac is a non-issue as I'm the only one who would ever adjust it. Obviously, need to check it after children come around 2-3 times a year.
I thought it was implied I knew the cause from my first post.
Ultimately my post was asking about KT88 v 6550WE and nothing about why the tube red plated.
My answer is that KT88 will be used within it's limits in this amp.
6550 (and KT120) is used outside their safe working limits, with an
enhanced risk of grid current runaway ( redplating)
The amp comes with 6550we thus ARE within the working limits of the amp , and, your response has nothing to do with the original intent of the question.