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Tube gear section.

Do you want a tube gear section ?


  • Total voters
    66

MattHooper

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Nah. You didn’t fail I think. It’s so hard to do a true A/B test, especially with rolling tubes. I did some half ass experiment years ago with a couple of friends. By the time we got the new tubes in the amp. Biased them and reset SPL it was 20 minutes later. Might has well been 20 months later at that point. I personally didn’t hear differences. A couple of us thought we heard something different. But I don’t think anyone could say it was better with a $30 Tung Sol 6sn7 vs. $200 NOS Tube. Heard nothing different rolling rectifier tubes. My amp can take different power tubes so might have been a difference there but would want a cleaner test than we did to confirm

No but that's the thing: Having two pairs of the exact same amplifiers I (or my blind test helper) could have have switched between them basically instantly!
That was the opportunity I had. I was told there were steps I could take to make it safer to leave both amps on to switch the speaker cables between them.
But for the reasons I gave I didn't end up doing the test.
 

GXAlan

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No. [tube tester]

I don’t think I have golden ears. But anytime I think something is off, even if I cannot describe it in words, something measures off when I check the tubes on a tube tester. Swap to new tubes and it sounds good again.

The BK 707 tester I have had a life mode which definitely correlates with perceived sound quality.
A bias pot for each output tube. So manually, each time I change power tubes.

That’s great. As the tubes age, you may need to tweak it as well.


Yeah...I dunno. As I understand it, while the KT120 tubes can under the right circumstances produce more power, you don't just get more power dropping them in place of 6550s. The amp has to be designed specifically to get that extra power out of the KT120. (And even then, it's not a huge gain).

That’s right. In theory, same tube at same bias is the same. It’s that the KT120 can handle more bias than the EL34.

Then there’s the transformer. If you have a small transformer, it can only handle so much power.


More intriguing is that, after I heard this difference I started to research the tube and came upon review after review from other tube amp owners trying the KT120 in place of other power tubes (like 6550s/KT88s). Over and over the differences they reported mirrored what stuck out to me: deeper, weightier, tighter bass and more extended sounding highs.

Did you have the 6550 and Kt120 at the same exact bias?
 

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MattHooper

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Did you have the 6550 and Kt120 at the same exact bias?

I'm not sure of the answer.

If you mean did I keep the same bias settings without touching them when I substituted the KT120s, no. I changed the bias for the KT120s.

For my amp the process is putting in new tubes, turning the bias screws until the red light turns on, then slightly backing off until the red light is off. (And doing that again about 30 minutes after turning them on). Then that should be it for the most part.

The KT120s certainly end up at a different point on the "bias dial" than the 6550s when doing this. But in each case, both are biased just until the red light comes on, then slightly dialed back until the light is off.

So would that count as having both tube types at the same bias?

(I'm really...really!...not good with electronic theory...so this is about as far as I go with this stuff).
 

GXAlan

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The KT120s certainly end up at a different point on the "bias dial" than the 6550s when doing this. But in each case, both are biased just until the red light comes on, then slightly dialed back until the light is off.

So would that count as having both tube types at the same bias?

You know, I am not sure how they configure the LEDs. This post suggests that the “6550's may need less bias due to their current requirements” and that may mean that you are underbiasing the 6550’s?


Hard to know. I had the MCIntosh Mc2102 which was fixed bias a long time ago and currently have the SFS-80 which has an actual meter so I can dial it to taste.
 

MattHooper

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You know, I am not sure how they configure the LEDs. This post suggests that the “6550's may need less bias due to their current requirements” and that may mean that you are underbiasing the 6550’s?


Hard to know. I had the MCIntosh Mc2102 which was fixed bias a long time ago and currently have the SFS-80 which has an actual meter so I can dial it to taste.

Interesting. Thanks. Not sure I process what that entails. I just follow the manual.
 

GXAlan

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Interesting. Thanks. Not sure I process what that entails. I just follow the manual.

I am wondering if there is a way for you to reach out to CJ customer service and they can look up your serial number and tell you what the light is set for.

In theory, if it was a regular amp or voltmeter and it was configured for a 6550/KT88, and you were using a KT120 and the transformers easily could handle it, instead of turning the light on and then backing off, you could just barely turn on the light or be in the scenario where loud music turns on the light routinely.

Again, as long as the transformers (and everything else) can handle the peak power of the KT120 you generally would want to run it at slightly higher bias to take advantage of the higher dissipation rating.

All conjecture of course.

By way of example on the SFS-80, they recommend 50 mA for the 6550/KT88 but if you run it in 40 mA, you will get longer life out of the tubes with less power. Having that freedom is great.
 

Waxx

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By way of example on the SFS-80, they recommend 50 mA for the 6550/KT88 but if you run it in 40 mA, you will get longer life out of the tubes with less power. Having that freedom is great.
In that sensee, the tube amp i have use EL34's (altough it has autobias and can run KT88 or KT120's also) and as it runs them on lower voltage than most the tubes last longer and distort less. The power output is lower off course. I know amps that give about 100w with a pair of EL34's while mine gives 35watts. But my first pair of EL34's lasted 4 years with daily use.

The real advantage of tubes is a combination of harmonic distortion in the right kind (lower order dominant), the lower damping factor and that it does not give the ugly non-harmonic distiortion that solid state devies give when driven hard. With the right speakers this gives a more pleasant sound, even if Sinad is relative bad. I use both solid state (class A, AB and D) and tube gear in my different setups and the difference in sound is obvious, even for people who hardly know the difference (like the sons of my brother who are 6 and 4 years old). It's a preference, and tubes are technical inferior to class D and wel engineerd class AB amps, but i and many like it.
 

MattHooper

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I think that tube amp owners view the amplifiers more as pets than amplifiers.

No denying there's an aspect of that :)

Then again...the amount of time other folks spend fiddling with room EQ, subwoofer crossovers, fiddling with their server software, their music library software etc...pets take on different forms :)
 

DMill

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No denying there's an aspect of that :)

Then again...the amount of time other folks spend fiddling with room EQ, subwoofer crossovers, fiddling with their server software, their music library software etc...pets take on different forms :)
Well said. My tube amp has never had my girlfriend asking my why I’m crawling around my family room floor trying to figure out where to put a giant black box where she will then tell me, “you aren’t honestly gonna put that there, are you?!”
 

MattHooper

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I am wondering if there is a way for you to reach out to CJ customer service and they can look up your serial number and tell you what the light is set for.

In theory, if it was a regular amp or voltmeter and it was configured for a 6550/KT88, and you were using a KT120 and the transformers easily could handle it, instead of turning the light on and then backing off, you could just barely turn on the light or be in the scenario where loud music turns on the light routinely.

Again, as long as the transformers (and everything else) can handle the peak power of the KT120 you generally would want to run it at slightly higher bias to take advantage of the higher dissipation rating.

All conjecture of course.

By way of example on the SFS-80, they recommend 50 mA for the 6550/KT88 but if you run it in 40 mA, you will get longer life out of the tubes with less power. Having that freedom is great.

Ok that's interesting. Thanks. Apparently (from an old review) the LEDs flash when the amp puts out more than 5W. I've very rarely seen them flash.
 

MattHooper

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I actually got around to noticing the poll results.

It has me somewhat puzzled.

I know there aren't a majority of ASR members actually clamoring for a Tube Gear Section of the forum.

But taking the poll to be a "For or Against" the notion of a Tube Gear Section poll...then I'm curious why many voted "No."

I mean, why not? What would having that additional forum do that puts you against it? It would be another place to discuss some of the gear some ASR members use and are interested in.

Why would you want to put a stop to a section other people may find useful and enjoy? If you don't care about tube gear...you just don't bother going to that section. Just like if you don't care for vinyl you don't have to participate in the Phono/Turntable section. I don't care for headphones at all, but I wouldn't have voted against creating the headphone section of the forum - it serves some member's interest.

??? :confused:
 

Midnight Audiophile

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Why would you want to put a stop to a section other people may find useful and enjoy?

It's gatekeeping based on confirmation/affirmation bias. You see it sprinkled all through these forums. It's silly and immature on a site that should be based on skepticism and science.
 

GXAlan

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I guess audio science also includes the science of designing stuff that is not high fidelity - but meets peoples other wants.

That is the science behind the Harman headphone curve and bass bumps. Theoretically, if a perfectly flat speaker generates a standard headphone curve, that's the purest translation. But people want, in properly designed studies, more bass particularly if they are younger. That's science applied toward wants.

Headphones should be dual mono. But people like crossfeed, which is less "truthful" but sounds better.

Within tubes, I am not convinced it is simply even vs. odd harmonics, sighted bias, etc. It's more likely than not, the reactivity of the load leading to some bass boosts/drops, damping factors in the single digits at times, and the differences at very low level signals. There are hints of science behind that, but it hasn't been applied yet because testing amplifiers is a lot harder than testing line-level gear.

There's plenty of tube hocus-pocus/snake oil which is why there is value in a science based discussion of tubes. It's like trying to understand how to make a better motorcycle when everyone else is just using a car to commute.
 

egellings

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No denying there's an aspect of that :)

Then again...the amount of time other folks spend fiddling with room EQ, subwoofer crossovers, fiddling with their server software, their music library software etc...pets take on different forms :)
True, Some people like dogs, others like cats, reptiles or perhaps some crazy bird.
 

Robin L

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I guess audio science also includes the science of designing stuff that is not high fidelity - but meets peoples other wants.
File under "Psychoacoustics" (with the emphasis on "psycho").

Seriously, finding a genuinely high-fidelity tube amp would be interesting and valuable. And finding one that is objectively poor but subjectively lovely is possible as well.
 

egellings

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I actually got around to noticing the poll results.

It has me somewhat puzzled.

I know there aren't a majority of ASR members actually clamoring for a Tube Gear Section of the forum.

But taking the poll to be a "For or Against" the notion of a Tube Gear Section poll...then I'm curious why many voted "No."

I mean, why not? What would having that additional forum do that puts you against it? It would be another place to discuss some of the gear some ASR members use and are interested in.

Why would you want to put a stop to a section other people may find useful and enjoy? If you don't care about tube gear...you just don't bother going to that section. Just like if you don't care for vinyl you don't have to participate in the Phono/Turntable section. I don't care for headphones at all, but I wouldn't have voted against creating the headphone section of the forum - it serves some member's interest.

??? :confused:
Maybe people don't want a tube amp section on this site is that readers of this site are more into optimized measurement results, and tubes simply need not apply for the job, since they return inferior results on the test bench compared to S. S. gear.
 

Doodski

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@MattHooper and @egellings oftentimes the help/assistance coming from peeps for other peeps is from tube gear heads. They are a resource unto themselves and for others too.
 

MattHooper

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Maybe people don't want a tube amp section on this site is that readers of this site are more into optimized measurement results, and tubes simply need not apply for the job, since they return inferior results on the test bench compared to S. S. gear.

Yes but:

1. Tube amps can be made audibly indistinguishable from solid state (and some members here enjoy making/tinkering with such tube amps).

2. My main point was why would someone take their personal goal for optimized measurements as a reason to deny a forum that would suit others? As I've said, it seems the forum's wider remit is conveying/obtaining accurate information about how any particular audio gear performs. Then the choice is up to the individual. The fact the forum already has a subsection devoted to vinyl playback (and Amir reviews phono stages) supports this. Not to mention, the two aren't mutually exclusive: someone may seek and enjoy both "best measuring gear they can buy" AND dalliances with other types of gear. (Just as people here may listen both to digital sources and sometimes their turntable. And they can go to the phono/turntable/cartridges subsection to get accurate help or info when dealing with that gear).
 
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