Don't know you will ever be able to find consensus on this question, but I have built both, and found the Byrith circuit to be an improvement on the Mullard. Less to worry about, less to tweak/adjust, and less concern about tube matching. An far fewer concerns about wiper issues.
That is not to say Mullard didn't know what they were doing, but technology/chemistry/materials improve with time. Mullard, from a practical standpoint, did not have CCS available at the time. If they did, would they have placed a CCS in the tail? I suspect so.
Is the only way to have a turntable to build it like Edison? Perhaps one wants a smartphone, and one might prefer the old Motorola Razr, but how many of us actually continue to use rotary phones? Mullard's 5-20 is more like a Razr to me.
Yes I suspect that Mullard would have used a ccs if they were available back then. Did you use a ccs in your build if so would you be willing to share what you used?
Thanks for sharing your design. please forgive this Dumb question, but can you explain how the negative bias circuit works? I can't see where the individual EL34's connect, do they connect at the upper end ot each trim pot?
Hi Kurt, thanks for the circuits that's an interesting amp I assume 10W is in triode mode how many watts do you get in ultra linear mode and which do you prefer? this is a long shot, but do you still have any boards left for your B+ time delay circuit?
Sure, I have a few boards left. PM me.
The amp is currently in use by a family member, and not in my possession. I don't recall getting too many extra watts in UL. It serves more to slightly lower output impedance as I recall. Either way, I do remember the ears always preferring triode mode, to the point I don't bother wiring up any of my amps with UL options any longer.
The amp is currently in use by a family member, and not in my possession. I don't recall getting too many extra watts in UL. It serves more to slightly lower output impedance as I recall. Either way, I do remember the ears always preferring triode mode, to the point I don't bother wiring up any of my amps with UL options any longer.
All other things being equal:
Ultra Linear mode has a Lower damping factor, versus Triode Wired output tubes.
To make things "equal", the output stages will be run with no Global, no Schade, and no output transformer-to-Cathode types of negative feedback.
(those types of negative feedback will Increase the damping factor; how much depends on the amount of negative feedback).
1. Damping Factor . . . Consider the different output modes:
Ultra Linear, Typically 25% to 50% plate-to-screen negative feedback. Medium damping factor.
The lower the UL tap % is, the higher the output power, but the Lower the damping factor is.
To technically be real Ultra Linear, the tap % varies, according to the output tube type.
Triode wired, 100% plate-to-screen negative feedback. Highest damping factor. Lowest output power.
Pentode mode, Beam Power mode, 0% plate-to -screen negative feedback. Lowest damping factor. Highest output power.
2. Distortion . . . Consider the distortion without Global, Schade, or Cathode negative feedback:
Run the amplifier power at 20% to 40% of their [different] maximum rated power(s), then the Harmonic Distortion is Typically:
Pentode and Beam Power mode; Highest distortion
Ultra Linear; Medium distortion
Triode Wired; Lowest distortion.
Tradeoffs, Tradeoffs, Tradeoffs.
There is no free lunch, except when standing in the charity food line.
I hope that helps.
Have Fun!
Ultra Linear mode has a Lower damping factor, versus Triode Wired output tubes.
To make things "equal", the output stages will be run with no Global, no Schade, and no output transformer-to-Cathode types of negative feedback.
(those types of negative feedback will Increase the damping factor; how much depends on the amount of negative feedback).
1. Damping Factor . . . Consider the different output modes:
Ultra Linear, Typically 25% to 50% plate-to-screen negative feedback. Medium damping factor.
The lower the UL tap % is, the higher the output power, but the Lower the damping factor is.
To technically be real Ultra Linear, the tap % varies, according to the output tube type.
Triode wired, 100% plate-to-screen negative feedback. Highest damping factor. Lowest output power.
Pentode mode, Beam Power mode, 0% plate-to -screen negative feedback. Lowest damping factor. Highest output power.
2. Distortion . . . Consider the distortion without Global, Schade, or Cathode negative feedback:
Run the amplifier power at 20% to 40% of their [different] maximum rated power(s), then the Harmonic Distortion is Typically:
Pentode and Beam Power mode; Highest distortion
Ultra Linear; Medium distortion
Triode Wired; Lowest distortion.
Tradeoffs, Tradeoffs, Tradeoffs.
There is no free lunch, except when standing in the charity food line.
I hope that helps.
Have Fun!
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Yes I think my next amp build will be a pp triode amp. anyone have any suggestions for a good circuit I can build?
Does the damping factor falls when beam power tube is connected as triode ( 807 ) but goes from A class to AB1 class ?
krca,
The simple answer is Yes, in AB1 the damping factor goes down.
Our world is Dynamic, not Linear.
Now for the details, perhaps enough to keep you from sleeping at night:
Class A operation; and the Class A "region" of Class AB1:
When both triode wired 807 tubes are conducting current, the damping factor is relatively high.
And . . . because it is push pull, the damping factor is relatively Symmetrical from the positive signal excursion, to zero crossing, to the negative signal excursion.
Even though the rp of each tube varies a little from quiescent current, to peak current, to lowest current, the damping factor varies (output impedance varies) but it does that Symmetrically because of the push pull balance.
Class AB1 operation, in the "regions" of Class AB1, not the "region" of Class A:
That is a Lower damping factor, because . . .
When one triode wired 807 tube is cut off (not conducting current), the damping factor is Low . . . about 1/2 of the Class A damping factor.
But because it is push pull, the damping factor is relatively Symmetrical in the Class AB1 "regions". That is because in the Class AB1 "regions", one tube is cut off, and the other has full current.
But the damping factor is Symmetrical because of the push pull balance.
The variable damping factor of both Class A "region", and the damping factor of Class AB1 "regions" are Dynamic within those "regions"; but push pull makes it Symmetrical.
Single Ended damping factor not only is variable, it is not Symmetric.
Does your woofer care about Symmetrical drive, versus Non-Symmetrical drive?
Ask your woofer.
I hope that makes it clear, even though it is hard to describe, and hard to visualize.
I learned to "see" things dynamically versus the time element.
During my carrier, I learned to "see" [visuallize] the path of the symbols in digital modulation, including the digital filter acceleration and deceleration, the filter undershoot and overshoot, rotation due to velocity (doppler), and various kinds of fading.
With all of that versus time (three dimensional).
It is done in the mind, so that when you see the actual display, you can analyze which or all of those factors are going on (can be played back in slow motion). Test equipment is very sophisticated.
I bet that TubeLab_com may have visualized something like that too. (Spelling of his moniker?)
$0.03 (includes inflation)
The simple answer is Yes, in AB1 the damping factor goes down.
Our world is Dynamic, not Linear.
Now for the details, perhaps enough to keep you from sleeping at night:
Class A operation; and the Class A "region" of Class AB1:
When both triode wired 807 tubes are conducting current, the damping factor is relatively high.
And . . . because it is push pull, the damping factor is relatively Symmetrical from the positive signal excursion, to zero crossing, to the negative signal excursion.
Even though the rp of each tube varies a little from quiescent current, to peak current, to lowest current, the damping factor varies (output impedance varies) but it does that Symmetrically because of the push pull balance.
Class AB1 operation, in the "regions" of Class AB1, not the "region" of Class A:
That is a Lower damping factor, because . . .
When one triode wired 807 tube is cut off (not conducting current), the damping factor is Low . . . about 1/2 of the Class A damping factor.
But because it is push pull, the damping factor is relatively Symmetrical in the Class AB1 "regions". That is because in the Class AB1 "regions", one tube is cut off, and the other has full current.
But the damping factor is Symmetrical because of the push pull balance.
The variable damping factor of both Class A "region", and the damping factor of Class AB1 "regions" are Dynamic within those "regions"; but push pull makes it Symmetrical.
Single Ended damping factor not only is variable, it is not Symmetric.
Does your woofer care about Symmetrical drive, versus Non-Symmetrical drive?
Ask your woofer.
I hope that makes it clear, even though it is hard to describe, and hard to visualize.
I learned to "see" things dynamically versus the time element.
During my carrier, I learned to "see" [visuallize] the path of the symbols in digital modulation, including the digital filter acceleration and deceleration, the filter undershoot and overshoot, rotation due to velocity (doppler), and various kinds of fading.
With all of that versus time (three dimensional).
It is done in the mind, so that when you see the actual display, you can analyze which or all of those factors are going on (can be played back in slow motion). Test equipment is very sophisticated.
I bet that TubeLab_com may have visualized something like that too. (Spelling of his moniker?)
$0.03 (includes inflation)
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