Thanks Stephe, I was waiting patiently for a design and I like the idea of this.!
Also remember to let me know what size you need that plinth made and some basic details I’ll get it shipped out for you. Thanks again for your help.
Also remember to let me know what size you need that plinth made and some basic details I’ll get it shipped out for you. Thanks again for your help.
I just finished Pete Millets uniamps with kt88 and like it a lot. I think the 40 watt outputs will work as that is what I am using except 6600 on the primarys.
zintolo, (and everyone)
Post # 19 . . .
Uses a KT120 Beam Power Tube, it is Not a true Pentode it has Beam Formers, it does Not have a Suppressor Grid).
Uses Schade negative feedback (I think you called that shunt feedback).
Uses Ultra Linear (negative feedback).
That is a very interesting way to get a few more watts.
I wish everyone always called an EL34 a Pentode tube.
I wish everyone always called a KT77 a Beam Power tube.
Then, I wish that what everyone called a tube was according to whether it used Beam Formers, or it used Suppressor Grids.
OK, OK, so Tungsol calls the KT120 a Beam Pentode. At least they got the word Beam in the description.
Anybody have a KT120 they can look at?
Does it have . . .
Beam Formers
Or
Suppressor Screen
(It is not going to have both)
Thanks if you can look and tell us!
Post # 19 . . .
Uses a KT120 Beam Power Tube, it is Not a true Pentode it has Beam Formers, it does Not have a Suppressor Grid).
Uses Schade negative feedback (I think you called that shunt feedback).
Uses Ultra Linear (negative feedback).
That is a very interesting way to get a few more watts.
I wish everyone always called an EL34 a Pentode tube.
I wish everyone always called a KT77 a Beam Power tube.
Then, I wish that what everyone called a tube was according to whether it used Beam Formers, or it used Suppressor Grids.
OK, OK, so Tungsol calls the KT120 a Beam Pentode. At least they got the word Beam in the description.
Anybody have a KT120 they can look at?
Does it have . . .
Beam Formers
Or
Suppressor Screen
(It is not going to have both)
Thanks if you can look and tell us!
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@6A3sUMMER
I admit I can’t recognize a tube that is a pentode or a beam… I post this photo, can you explain me how to do it? Thanks!
I admit I can’t recognize a tube that is a pentode or a beam… I post this photo, can you explain me how to do it? Thanks!
Below is copied from a post of his on the Bottlehead forum:
"Simplistic summary:
1) Most ordinary solid-state amps put out more than enough power for most ordinary speakers.
2) SET amps need high efficiency speakers to attain the loudness most audiophiles want.
Over the years, I have tried to gather enough data to make those vague rules more specific. It is complicated (isn't everything?!) by the notion of headroom. Loudness is measured typically as a short-term average, over something like 1/4 second. But the instantaneous peak power, for example hitting a drum, or the initial impulse of a guitar or piano, is much greater. For well-recorded music, the initial impulses are about 25 times more power than the peak you see on the loudness meter. That's about 14dB headroom. So if you listen at a level that gives measured peaks of 82dB, you need an instantaneous peak of 96dB if you do not want to hear clipping distortion. I chose 82dB because that is typical of the level used by recording engineers. Movies typically need 6dB (four times as much, i.e. 102dB). The THX standard for movie theaters calls for peak levels of 102dB per channel, which is consistent with the recording engineer levels. Some 20 years ago, I gathered a bunch of speaker reviews from Stereophile, which give a minimum-power rating and the speaker sensitivity. I got the same number (102dB peaks) again. So I think that 102dB peaks is enough for most audiophiles, most of the time, and 96dB peaks are enough for the average audiophile. These numbers are somewhat affected by room acoustics (size and absorption), and more strongly affected by your personal preferences and choice of music.
Amplifier power is most usefully expressed in dB, which can be added to the speaker sensitivity to get the peak level. Here's a short table:
1 watt = 0dB
2 watts = 3dB
4 watts = 6dB
8 watts = 9dB
16 watts = 12dB
32 watts = 15dB
64 watts = 18dB
So for example an 86dB speaker needs 10 to 40 watts to obtain undistorted peaks of 96 to 102dB.
These rules are quite flexible, of course. I have two systems in my own home, the music system has 101dB speakers with 8-watt amplifiers (110dB peaks) and the movie system in another room has 89dB speaker with a 2-watt amp (92dB peaks). Both are quite satisfactory to us, for the sounds we listen to.
I know that is a lot to take in, and it's still over-simplified, but I hope that is at least some help!"
"Simplistic summary:
1) Most ordinary solid-state amps put out more than enough power for most ordinary speakers.
2) SET amps need high efficiency speakers to attain the loudness most audiophiles want.
Over the years, I have tried to gather enough data to make those vague rules more specific. It is complicated (isn't everything?!) by the notion of headroom. Loudness is measured typically as a short-term average, over something like 1/4 second. But the instantaneous peak power, for example hitting a drum, or the initial impulse of a guitar or piano, is much greater. For well-recorded music, the initial impulses are about 25 times more power than the peak you see on the loudness meter. That's about 14dB headroom. So if you listen at a level that gives measured peaks of 82dB, you need an instantaneous peak of 96dB if you do not want to hear clipping distortion. I chose 82dB because that is typical of the level used by recording engineers. Movies typically need 6dB (four times as much, i.e. 102dB). The THX standard for movie theaters calls for peak levels of 102dB per channel, which is consistent with the recording engineer levels. Some 20 years ago, I gathered a bunch of speaker reviews from Stereophile, which give a minimum-power rating and the speaker sensitivity. I got the same number (102dB peaks) again. So I think that 102dB peaks is enough for most audiophiles, most of the time, and 96dB peaks are enough for the average audiophile. These numbers are somewhat affected by room acoustics (size and absorption), and more strongly affected by your personal preferences and choice of music.
Amplifier power is most usefully expressed in dB, which can be added to the speaker sensitivity to get the peak level. Here's a short table:
1 watt = 0dB
2 watts = 3dB
4 watts = 6dB
8 watts = 9dB
16 watts = 12dB
32 watts = 15dB
64 watts = 18dB
So for example an 86dB speaker needs 10 to 40 watts to obtain undistorted peaks of 96 to 102dB.
These rules are quite flexible, of course. I have two systems in my own home, the music system has 101dB speakers with 8-watt amplifiers (110dB peaks) and the movie system in another room has 89dB speaker with a 2-watt amp (92dB peaks). Both are quite satisfactory to us, for the sounds we listen to.
I know that is a lot to take in, and it's still over-simplified, but I hope that is at least some help!"
There are many 'rules'
One is the '102dB' rule
I do not know the year of the earliest statement of that rule.
Another 'rule' is that if you are considering purchasing a new amplifier, it should have at least 2x the power of the amplifier you are replacing
(+ 3dB or more power than the old amplifier)
I do not know the year of the earliest statement of that 'rule', but I remember that it was stated long before Bottle Head amplifiers, and long before Valve magazine, etc. (Stated at least as early as the 1960s).
Here is another 'rule': Play it too loud for too long, and your hearing will be degraded.
And the more your hearing is degraded, the louder you will turn it up to hear what you want.
As far as books go, the two US Marine manuals do not list the location of the chow hall, but every Marine figures it out.
(stolen from "A Few Good Men", in case you forgot . . . watch the movie).
When it comes to 'rules',
Remember to carefully consider this quote:
"All Generalizations Have Exceptions"
You might consider that quote to have a 0.0dB Return Loss (Rho of 1.0).
Spock would have trouble with it.
One is the '102dB' rule
I do not know the year of the earliest statement of that rule.
Another 'rule' is that if you are considering purchasing a new amplifier, it should have at least 2x the power of the amplifier you are replacing
(+ 3dB or more power than the old amplifier)
I do not know the year of the earliest statement of that 'rule', but I remember that it was stated long before Bottle Head amplifiers, and long before Valve magazine, etc. (Stated at least as early as the 1960s).
Here is another 'rule': Play it too loud for too long, and your hearing will be degraded.
And the more your hearing is degraded, the louder you will turn it up to hear what you want.
As far as books go, the two US Marine manuals do not list the location of the chow hall, but every Marine figures it out.
(stolen from "A Few Good Men", in case you forgot . . . watch the movie).
When it comes to 'rules',
Remember to carefully consider this quote:
"All Generalizations Have Exceptions"
You might consider that quote to have a 0.0dB Return Loss (Rho of 1.0).
Spock would have trouble with it.
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Zintolo,
I might try next week to put up some photos that show some Beam Formers, and some Suppressor Grids.
Until than, most RCA tube manuals have drawings of both a Pentode, and a Beam Power tube that shows the difference.
Once you learn what to look for, you will usually find the difference easy to spot.
The Beam Formers are sheets of metal, it narrows up as the metal comes through the Mica at the top of the tube.
Look at the top mica insulator, and notice what passes through it.
Tube grids wires are wrapped around vertical rods. There are 2 grids and Beam formers, or 3 grids.
That makes 4 vertical rods (Beam Power), or 6 vertical rods (Pentode) respectively.
Beam Power tube: You see the vertical cathode, the 2 control grid vertical rods, the 2 screen grid vertical rods, and the sheet metal formers.
Then last, you see the plate (often with the plate sheet metal narrowing and coming through the mica, similar to the Beam Formers.
Pentode: You see the vertical cathode, the 2 control grid vertical rods, the 2 screen grid vertical rods, and the suppressor grid vertical rods.
Then last, you see the plate (often with the sheet metal coming through the mica).
Look closely; use a moderate power magnifying glass.
Hints:
If you can see holes in the plate, on a Beam Power tube, you sometimes can see the beam former sheet behind the holes.
If you can see holes in the plate, on a Pentode, you sometimes can see the suppressor grid vertical rods behind the holes.
I just love the almost duplicate specs of some tubes that are built quite differently (Beam Power versus Pentode).
Examples:
KT77 & EL34
6BQ5 & EL84
Have fun listening and trying to the hear differences (try using a simple test method; or go completely wild and use a double blind test method).
I might try next week to put up some photos that show some Beam Formers, and some Suppressor Grids.
Until than, most RCA tube manuals have drawings of both a Pentode, and a Beam Power tube that shows the difference.
Once you learn what to look for, you will usually find the difference easy to spot.
The Beam Formers are sheets of metal, it narrows up as the metal comes through the Mica at the top of the tube.
Look at the top mica insulator, and notice what passes through it.
Tube grids wires are wrapped around vertical rods. There are 2 grids and Beam formers, or 3 grids.
That makes 4 vertical rods (Beam Power), or 6 vertical rods (Pentode) respectively.
Beam Power tube: You see the vertical cathode, the 2 control grid vertical rods, the 2 screen grid vertical rods, and the sheet metal formers.
Then last, you see the plate (often with the plate sheet metal narrowing and coming through the mica, similar to the Beam Formers.
Pentode: You see the vertical cathode, the 2 control grid vertical rods, the 2 screen grid vertical rods, and the suppressor grid vertical rods.
Then last, you see the plate (often with the sheet metal coming through the mica).
Look closely; use a moderate power magnifying glass.
Hints:
If you can see holes in the plate, on a Beam Power tube, you sometimes can see the beam former sheet behind the holes.
If you can see holes in the plate, on a Pentode, you sometimes can see the suppressor grid vertical rods behind the holes.
I just love the almost duplicate specs of some tubes that are built quite differently (Beam Power versus Pentode).
Examples:
KT77 & EL34
6BQ5 & EL84
Have fun listening and trying to the hear differences (try using a simple test method; or go completely wild and use a double blind test method).
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Thanks @6A3sUMMER !
Not being at home, where I have a copy of the RH4, I read this link http://www.r-type.org/articles/art-004c.htm to see the differences, thanks!
I don’t know 6BQ5, but I’ve always found KT77 more linear than EL34 and IIRC they reacted better to low percentages of UL.
Not being at home, where I have a copy of the RH4, I read this link http://www.r-type.org/articles/art-004c.htm to see the differences, thanks!
I don’t know 6BQ5, but I’ve always found KT77 more linear than EL34 and IIRC they reacted better to low percentages of UL.
102 dBs seems to include pretty much everyone, as alluded to above many can get by with quite a bit less.
I think that is the most important rule. As soon as the continuous level approaches 85 dB hearing will self-protect by closing down more and more as the level goes up. Then one needs to stay away in a quiet environment for some time to recover. Listening at higher continuous levels than 80 dB makes the quality of the system less important.
If wanna keep max sensitivity better to stay in the range between 70 and 80 dB most of the time. Closer to 70 average at listening position or to 80 average will depend on the kind of music. For example, the lower limit would be more likely appropriate with large acoustic musical ensembles and the higher limit with rock, small ensembles etc (where peak level is not much more than average). I would say that 90 dB (+3dB peak on top of it) are already enough in most cases. That means that even with average 86 dB/1W/1m speakers one doesn't need a lot of power. Say 5W (+7 dB) typical SE tube which is capable of +3dB for short transients, then average minus 5-6 dB at listening position, +3 dB for the stereo pair that results in 90-91 dB peak at listening position which is objectively loud. I can bet no one will say that is not, unless already exposed to ear damaging levels.....
A well made single-ended amplifier 2 x 4 - 5W is very loud in a normal room/apartment , using decent "big" speakers .
Of course they knew it when they made "small" tubes like EL84 and many others
Of course they knew it when they made "small" tubes like EL84 and many others