Hmmm...how do you know if more mercury is there ? Brighter ? When I was asking about brightness, I was talking about rca 866, all look the same...but two light significantly brighter then the other two...current and voltage the same.
I am listening currently first time to an 83...compared to an 866 it seems a bit less musical, more technical...I was just thinking if I should compare it to a 816 or 866jr setup...with exactly the kind of logic either anode/cathode structure or amount of mercury makes a difference...
...which would open a new book like four 866a for a preamp...and in theory 872a, 722a or 249 for the power tubes ???
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The mercury droplets are clearly seen when cold. As is the amount of mist while warming up. Variations in sound between different makes/vintages are quite obvious. Most "technical" within my stock of 83s is a valve badged "National" which has entirely different looks. Most muisical: RCA from 1935.
Smile...yes, this looks like my 866a...I meant what is the amount you should be able to see in a 83.... mine show mybe a silver mirror coating, but no mercury droplets...
I do have a different question:
I got some spare heating transformers with 2,5-0-2,5V and enough current (4A/8A). Originally meant for a gz34 setup.
Here is the idead: In a Full-Wave setting, one 866A gets the winding between the first half 2,5-0 and the second 866a gets the other half of the winding 0-2,5V. HV is taken from the CT "0" Would that work ?
My thoughts:
- Well, each 866A has its own 2,5V winding, so even if they take different currents, they would stay within the voltage of that winding, no ?
- I have read that when parallel heater for a 866a use the same winding, the heater connection should be in parallel, meaning physically the same sockets pin to the same transformer winding as internally the tube is assymetric (i believe shielding was a topic)....so, would this matter here as well and if yes, which would be the right "polarity" ? Two options:
pin 1 of tube A goes to 2,5V, pin 4 of tube A to 0 (2.5V-0.....)
Now,
1. option: Pin 4 of Tube B goes as well to 0/CT and Pin 1 goes to 2.5V (....0-2.5V, the other half of the winding)
OR
2. option: Pin 1 of Tube B goes to 0/CT, Pin 4 goes to 2.5V
I do have a different question:
I got some spare heating transformers with 2,5-0-2,5V and enough current (4A/8A). Originally meant for a gz34 setup.
Here is the idead: In a Full-Wave setting, one 866A gets the winding between the first half 2,5-0 and the second 866a gets the other half of the winding 0-2,5V. HV is taken from the CT "0" Would that work ?
My thoughts:
- Well, each 866A has its own 2,5V winding, so even if they take different currents, they would stay within the voltage of that winding, no ?
- I have read that when parallel heater for a 866a use the same winding, the heater connection should be in parallel, meaning physically the same sockets pin to the same transformer winding as internally the tube is assymetric (i believe shielding was a topic)....so, would this matter here as well and if yes, which would be the right "polarity" ? Two options:
pin 1 of tube A goes to 2,5V, pin 4 of tube A to 0 (2.5V-0.....)
Now,
1. option: Pin 4 of Tube B goes as well to 0/CT and Pin 1 goes to 2.5V (....0-2.5V, the other half of the winding)
OR
2. option: Pin 1 of Tube B goes to 0/CT, Pin 4 goes to 2.5V
Hmmm. Does this mirror remain after a proper warm up?
Ime the only 83 which developed a mirror was one that suffered several dead shorts. Not sure at all about the mechanism, but it looks like the mercury is fused into the glass. And yes, this would explain the lack of droplets.
Perhaps someone more knowledgeable about the physics may wish to elucidate.
No, they are completely clear once heated...
I got a batch of Taylor 866jr....wow...these guys have some very serious droplets inside...I have read thatthese guys are prone for arcing over...next experiment.
By the way: Has anyone listening impressions mercury rectifier like 866a vs. mercury thyratron ? I see them being used here and there, but no comments on the sonic benefits sofar...
I got a batch of Taylor 866jr....wow...these guys have some very serious droplets inside...I have read thatthese guys are prone for arcing over...next experiment.
By the way: Has anyone listening impressions mercury rectifier like 866a vs. mercury thyratron ? I see them being used here and there, but no comments on the sonic benefits sofar...
Quartz glass passes all uv, that´s why in street lamps is quartz high pressure burner, covered by outer normal glass bulb with phosphor coating on it.
Ok, it is time for a little intermediate report:
I tried different mercury rectifier in two psus: One for my differential DAC stage which are four 801A running each at 28mA/370V and the other 300B-PP running at 450V/54mA each.
On the DAC:
-83: sounded very clean, very good resolution, but as well a bit hard/cold/mechanic No go for me.
-Ck1006:Very warm, very nice tone. Nice looking glow, but dynamics are gone. Like going from 400HP to 70HP.
-866jr: Very warm as well, but with lots of dynamic more. but still not as transparent/clear as my normal Telefunken Mesh Rgn1064.
-RCA 866 ST: Nice optic and glow...a 300B which glows...you get here attack, transparency, speed very much. Quiet a different animal than the 866jr. This is a racing car. Lots of atmosphere. But a little harsh as weel in the treble.
-BBC Dq2/866: Very, very clean, but not the character of the RCA.
- RCA globe 866 with Inverted V: Combination of Warmth, resoultion and transparency. My favorite here (in my tube stage of the DAC)
On the 300B outputstage:
- RCA 866A: Same attributes like above, but not really harsh in the treble. You could stop here and be happy. Great value for money.
- RCA 866a globe: Softer, not as clear as the standard type here. not for my power amp. The normal version is stiffer and more transparent here.
- Cetron 249: The stiffest...really, really brutal. But for me not very musical. And the glow is huge...you need sun glasses, its like a warp-engine of Startrek.
- RCA 872a: Surprise. It has the highest burn-rate with 5v/7.5a...and I am running four of them...but: It sound very musical. Very BIG, very warm. Trebles are not as pronounced as with the 866a, but the 3D is big, voices have a lot of body, your amp sounds like 10k more expensive. This is a tiny 300B-PP ? Really ? This stays.
Next will be the test against thyratrons...in the house: 393a, 394a, 722a
Please post your personal experience on mercury tubes...(and please lets skip the disclaimer/education about mercury and/or discussions questioning that rectifiers do sound different...we are all adults, lets not waste our time on that).
I tried different mercury rectifier in two psus: One for my differential DAC stage which are four 801A running each at 28mA/370V and the other 300B-PP running at 450V/54mA each.
On the DAC:
-83: sounded very clean, very good resolution, but as well a bit hard/cold/mechanic No go for me.
-Ck1006:Very warm, very nice tone. Nice looking glow, but dynamics are gone. Like going from 400HP to 70HP.
-866jr: Very warm as well, but with lots of dynamic more. but still not as transparent/clear as my normal Telefunken Mesh Rgn1064.
-RCA 866 ST: Nice optic and glow...a 300B which glows...you get here attack, transparency, speed very much. Quiet a different animal than the 866jr. This is a racing car. Lots of atmosphere. But a little harsh as weel in the treble.
-BBC Dq2/866: Very, very clean, but not the character of the RCA.
- RCA globe 866 with Inverted V: Combination of Warmth, resoultion and transparency. My favorite here (in my tube stage of the DAC)
On the 300B outputstage:
- RCA 866A: Same attributes like above, but not really harsh in the treble. You could stop here and be happy. Great value for money.
- RCA 866a globe: Softer, not as clear as the standard type here. not for my power amp. The normal version is stiffer and more transparent here.
- Cetron 249: The stiffest...really, really brutal. But for me not very musical. And the glow is huge...you need sun glasses, its like a warp-engine of Startrek.
- RCA 872a: Surprise. It has the highest burn-rate with 5v/7.5a...and I am running four of them...but: It sound very musical. Very BIG, very warm. Trebles are not as pronounced as with the 866a, but the 3D is big, voices have a lot of body, your amp sounds like 10k more expensive. This is a tiny 300B-PP ? Really ? This stays.
Next will be the test against thyratrons...in the house: 393a, 394a, 722a
Please post your personal experience on mercury tubes...(and please lets skip the disclaimer/education about mercury and/or discussions questioning that rectifiers do sound different...we are all adults, lets not waste our time on that).
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No personal experience yet but will try a hybrid bridge with two 816 for negative side and a 5R4. For glow purpose and lower B+ by the way.
So easy to add windings with toroidal transformers, 2.5V CT is only a few turns..
816 filament is not power hungry, only 5W.
I wonder why most mercury rectifiers don't have a flash getter ? or is it a different getter?
From the picture, I tought it was for a getter?
So easy to add windings with toroidal transformers, 2.5V CT is only a few turns..
816 filament is not power hungry, only 5W.
I wonder why most mercury rectifiers don't have a flash getter ? or is it a different getter?
From the picture, I tought it was for a getter?
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Hi Blitz,
At what voltage (HV) are you running the 872A's? I have an ancient complete Full Wave PS that uses 4 GE equivalents of the 872A.
The voltage currently is adjustable using a massive 4 position switched Autoformer and oil caps. It's adjusts from about 2500V to 3500V.
Just curious at what voltage they will strike at and be stable.
Thanks!
If there is this much audible difference between these rectifiers they must be distressingly non-linear, or not suitable for the circuit they are used in. They are not something I would choose for use in reproducing music
Especially when combined with the issues with needing to shield the UV they produce.
Been using them for years with no ill effects noticed except I may have gotten better looking. Amateur radio guys used them for many years. I own and have read most every QST magazine from the mid 30's up through the mid 60's and don't recall any of the horror stories concerning MV tubes. It all comes down to common sense and respect for the equipment. There was the occasional flash over but these didn't result in bulb breakage. Strictly my opinion but running these at a few hundred milliamps at less that 1000V should present no problems. Please obey all HV rules as with any vacuum tube in this type of service.
Ok, I should have written ...no mercury and UV education...we are adults...my fault.
Seriously, these guys behave VERY different used in such low current and low voltage scenarios we have here with NF. The 872a is designed for 1.5A...and has to deliver 60mA in my case...Absolutely a joke. I tried them only because I was curious what this guy was talking about:
Space-Tech Laboratory - High-End Audio ...and he uses them for headphone amps...
I am not saying the 872A sounds best, the 866a can sound as good, its a matter of application case. But both can sound extremely nice and more important: Mercury rectifier do sound differently...as normal tube or SS rectifiers do as well.
Seriously, these guys behave VERY different used in such low current and low voltage scenarios we have here with NF. The 872a is designed for 1.5A...and has to deliver 60mA in my case...Absolutely a joke. I tried them only because I was curious what this guy was talking about:
Space-Tech Laboratory - High-End Audio ...and he uses them for headphone amps...
I am not saying the 872A sounds best, the 866a can sound as good, its a matter of application case. But both can sound extremely nice and more important: Mercury rectifier do sound differently...as normal tube or SS rectifiers do as well.
because this is not a bare vacuum tube.
these have pure mercury, or mercury/argon mix.
barium getter could be damaged by mercury i think.
but don´t quote me on ´dis
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