So if I was to run my pair of MK IVs thru a variac as I plan to do the setting should stay at 117 I notice now that summer is here the lights dim from time to time and well I think it would be better to run them at the correct level as they were designed for. Do most others do the same?
5 posters
Variac setting
WPFW893FM- Posts : 14
Join date : 2019-05-12
Peter W.- Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA
RANT WARNING!
a) A Variable Autotransformer ("Variac" is an active registered trade-mark) is not a constant voltage device. Meaning that it *MUST* be adjusted at each use, and, ideally during use should there be variations in line voltage.
b) To the extent that it is adjustable, it is superior to a built-in bucking transformer, which drops line voltage by a fixed amount irrespective of input voltage.
c) If you want a constant-voltage device, get a true-RMS line conditioner. That will hold your output voltage to your system at a given number. Depending on what you pay going in, that number will be fixed, or adjustable. Big numbers = adjustable output voltage.
I make no secret about greatly disliking the concept that our often-expensive equipment is not tolerant of modern-day Utility voltages based on tariffs. And I am absolutely flummoxed by half-baked solutions such as buckers or VATs - especially in light of those who install auto-bias systems. A line conditioner does solve the problem, and is automagical as it does so.
Cheap at the price.
a) A Variable Autotransformer ("Variac" is an active registered trade-mark) is not a constant voltage device. Meaning that it *MUST* be adjusted at each use, and, ideally during use should there be variations in line voltage.
b) To the extent that it is adjustable, it is superior to a built-in bucking transformer, which drops line voltage by a fixed amount irrespective of input voltage.
c) If you want a constant-voltage device, get a true-RMS line conditioner. That will hold your output voltage to your system at a given number. Depending on what you pay going in, that number will be fixed, or adjustable. Big numbers = adjustable output voltage.
I make no secret about greatly disliking the concept that our often-expensive equipment is not tolerant of modern-day Utility voltages based on tariffs. And I am absolutely flummoxed by half-baked solutions such as buckers or VATs - especially in light of those who install auto-bias systems. A line conditioner does solve the problem, and is automagical as it does so.
Cheap at the price.
Bob Latino- Admin
- Posts : 3276
Join date : 2008-11-26
Location : Massachusetts
Peter W. wrote:RANT WARNING!
A line conditioner does solve the problem, and is automagical as it does so.
Cheap at the price.
A line conditioner does NOT always "solve the problem" with a TUBE amp. Many line conditioners manipulate the AC and do NOT put out AC in the form of a true sine wave. A tube amp will choke big time if not fed AC in the form of a true sine wave. You do not know how many problems I have seen customers deal with over the past 13 years because they plugged their tube amp into a power conditioner instead of a wall outlet. This is not an indictment of ALL power conditioners but many low cost/cheaply made power conditioners do NOT put out AC in the form of a true sine wave. A variac will ALWAYS put out AC in the form of a true sine wave. True - a variac will not alter your AC up or down as your line voltage changes. The key to using a variac is to monitor the value of your AC over a few days and determine how the AC voltage varies at you location. Once you determine the highest AC voltage seen at your wall outlet, then have the variac put out 116 to 118 VAC on its AC outlet when your line voltage is at its highest point.
Bob
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Peter W.- Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA
You will notice two (2) Critical Phrases:
True RMS.
Depending on what you pay.
The voltage at our summer house will vary from 123 at 6:00 am to 115 at 7:00 pm in the peak summer season. When all that AC kicks in, I guess. We are pretty steady at home at 118. But that is not typical, as others here can attest. For that reason I run only solid-state stuff up there that is tolerant of voltage variations. Were I to run tubes, I would do it _only_ through a Furman.
https://www.amazon.com/Furman-P-1800-AR-Regularor-Conditioner/dp/B001UNPCCM/ref=pd_lpo_sbs_267_img_2?_encoding=UTF8&psc=1&refRID=THBNRBM01MR6D211K8DE
True RMS.
Depending on what you pay.
The voltage at our summer house will vary from 123 at 6:00 am to 115 at 7:00 pm in the peak summer season. When all that AC kicks in, I guess. We are pretty steady at home at 118. But that is not typical, as others here can attest. For that reason I run only solid-state stuff up there that is tolerant of voltage variations. Were I to run tubes, I would do it _only_ through a Furman.
https://www.amazon.com/Furman-P-1800-AR-Regularor-Conditioner/dp/B001UNPCCM/ref=pd_lpo_sbs_267_img_2?_encoding=UTF8&psc=1&refRID=THBNRBM01MR6D211K8DE
Bob Latino- Admin
- Posts : 3276
Join date : 2008-11-26
Location : Massachusetts
Peter W. wrote:You will notice two (2) Critical Phrases:
True RMS.
Depending on what you pay.
The voltage at our summer house will vary from 123 at 6:00 am to 115 at 7:00 pm in the peak summer season. When all that AC kicks in, I guess. We are pretty steady at home at 118. But that is not typical, as others here can attest. For that reason I run only solid-state stuff up there that is tolerant of voltage variations. Were I to run tubes, I would do it _only_ through a Furman.
https://www.amazon.com/Furman-P-1800-AR-Regularor-Conditioner/dp/B001UNPCCM/ref=pd_lpo_sbs_267_img_2?_encoding=UTF8&psc=1&refRID=THBNRBM01MR6D211K8DE
Yes - The Furman P-1800 is an excellent power conditioner but a lot of people don't have $1180 to sink into a power conditioner but they probably can come up with $60 for a 5 amp variac.
Bob
WPFW893FM- Posts : 14
Join date : 2019-05-12
thanks bob
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Last edited by PeterCapo on Mon Nov 30, 2020 4:23 pm; edited 1 time in total
Peter W.- Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA
To which I might add a Kill-O-Watt strip as a permanent voltage indicator.
http://www.p3international.com/products/p4330.html
I have no need (yet) for voltage control on the tube systems, but I do keep one of these as my power-strip. Calibrated to my Fluke VOM for accuracy. If one must choose a variable autotransformer option, real-time information without fuss or bother is critical.
http://www.p3international.com/products/p4330.html
I have no need (yet) for voltage control on the tube systems, but I do keep one of these as my power-strip. Calibrated to my Fluke VOM for accuracy. If one must choose a variable autotransformer option, real-time information without fuss or bother is critical.
bluemeanies- Posts : 274
Join date : 2015-02-09
Age : 74
Location : Folsom Pa.
I have both..Staco Variac purchased used for $100 bucks and the Kill-O-Watt.
The voltage fluctuations in my area are ridiculous. I lived only a few miles from the airport and closer to BOEING which according to my electric supplier is the main cause for such excentric variations.
I have experienced voltage levels as low as 115 and as high as 125.
It does not make any difference (at least in my situation) whether it is nighttime, daytime, summer or winter.
Glad I introduced them into my tube system.
The voltage fluctuations in my area are ridiculous. I lived only a few miles from the airport and closer to BOEING which according to my electric supplier is the main cause for such excentric variations.
I have experienced voltage levels as low as 115 and as high as 125.
It does not make any difference (at least in my situation) whether it is nighttime, daytime, summer or winter.
Glad I introduced them into my tube system.
10-E-C- Posts : 267
Join date : 2014-02-12
Age : 71
Location : upper east tn
bluemeanies wrote:I have both..Staco Variac purchased used for $100 bucks and the Kill-O-Watt.
The voltage fluctuations in my area are ridiculous. I lived only a few miles from the airport and closer to BOEING which according to my electric supplier is the main cause for such excentric variations.
I have experienced voltage levels as low as 115 and as high as 125.
It does not make any difference (at least in my situation) whether it is nighttime, daytime, summer or winter.
Glad I introduced them into my tube system.
I guess I'm lucky with my power, living in a smaller town of 15k and with TVA power, everytime I check my voltage it is 122.6 VAC and I use a Variac to 118 VAC. It's been over 5 years I've been checking my voltage, still the same.
TM