Need advice on rolling some tubes
polkfarmboy
Posts: 5,703
I just bought some tubes here on the forum and would like some advice
I have a yaqin mc10l and my old el34 b get a bias at 300 but today I added gold lion kt 77 and the bias reads 200 ? Just incase you ask I did not have anything but the speakers hooked up when this reading was taken also the volume was nil
Edit: Whats the proper setting on my digital multimeter I should be using
I have a yaqin mc10l and my old el34 b get a bias at 300 but today I added gold lion kt 77 and the bias reads 200 ? Just incase you ask I did not have anything but the speakers hooked up when this reading was taken also the volume was nil
Edit: Whats the proper setting on my digital multimeter I should be using
Post edited by polkfarmboy on
Comments
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what is the suggested bias per the manufacturer?JC approves....he told me so. (F-1 nut)
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george daniel wrote: »what is the suggested bias per the manufacturer?
Just got a pm from michaeljhsda and the reading is between 350 and 400 . But the gold lion gives me a reading of 200 so should I crank the bias way up to 350 ? -
350 to 400V.
Volume turned all the way down, speakers hooked up.
Doesn't matter if a CD player, etc. is connected.SDA SRS 2.3TL's
Silk Audio MS-90-BT integrated tube amp
Yaqin MS-20L integrated tube amp
SDA 2B TL's -
I am going to have another crack at biasing this later on maybe. Right now I powered down just in case I fry something on it
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Lol, we all see where this is going.....
I feel the report button being clicked, again! -
There's nothing to it. Just stick your probes in there and do it.SDA SRS 2.3TL's
Silk Audio MS-90-BT integrated tube amp
Yaqin MS-20L integrated tube amp
SDA 2B TL's -
Follow the instructions in the owners manual. It appears the Yaqin has made it super simple. You need to ensure the bias is set correctly for proper sound and tube life. I assume they provided you with a plastic tool for adjusting the bias pots? If not, don't use a metal screw driver. There is a special plactic tool similar to a screw driver for use on electronics where lots of voltage is present.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
Yep I got that lil hexi screw driver thanks , I just sent tubestein the seller on ebay to send me a copy of the manual again so I can check up on the gold lion kt77's
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polkfarmboy wrote: »But the gold lion gives me a reading of 200 so should I crank the bias way up to 350 ?
Yes.
In a story similar to what you experienced with the 200 reading on your MC-10L ... I rolled some Russian 6P3S-E's in a Yaqin MS-20L and the initial reading was 230 so I had to adjust the bias up to 400 for all 4 tubes. A couple days later I reinstalled the original Shuguang's and I had to turn down the bias for all 4 tubes because the was reading about 500 to start with.SDA SRS 2.3TL's
Silk Audio MS-90-BT integrated tube amp
Yaqin MS-20L integrated tube amp
SDA 2B TL's -
Also as an FYI, as tubes get more hours on them you should periodically check the bias to make sure it's where it needs to be. Since I usually am running used old stock power tubes on my Dared VP16, I check the bias about every 6 months. As a tube ages the bias will change. I use 6 months as a mark because it doesn't get constant use. If your amp gets constant use you may want to check it more often, maybe every 3-4 months so. Even with mine I've noticed little change (maybe 25 mV) in that time.
Also anytime you swap power tubes your should check the bias, every tube can vary, from slightly to a lot especially if they are a different tube designation. They will all need more or less bias, etc.
The Yaqin is simple compared to mine. I have to flip it over, power it up, pull the bottom cover off, find the probe points and then adjust the 4 pots.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
Two words for ya all. "Easy Bias", no fuss no muss! Tunes them in every time, on time!
cnhCurrently orbiting Bowie's Blackstar.!
Polk Lsi-7s, Def Tech 8" sub, HK 3490, HK HD 990 (CDP/DAC), AKG Q701s
[sig. changed on a monthly basis as I rotate in and out of my stash] -
I prefer manual bias actually. Plus you get a tad more power vs. auto bias. Fixed bias can be a nightmare in the sense you really need to use matched tubes to get consistent output.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
Well michael I just confirmed your findings about the different bias points. I loaded up my el34's and checked the bias and they were back to the original values of 350 +
Just like you said heiney .... some of my tubes changed drastically in values since I last checked em. One tube in V1 was at 300 and V4 was around 412. I will have to keep an eye on this more closely if it could cause damage to the amp.
Well I feel pretty confident now about cranking the values of the genalex from 200 up to 350 +. I always thought that the genalex kt77's were the same and you just plop em in but now I know and I thank you guys for the guidance -
Ah yeah,,old school,,pull that bottom cover off ---thats the type of bias adjustment I love--one slip and down the hall we fall. :cool:JC approves....he told me so. (F-1 nut)
