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Post by gtrjunior on Jul 18, 2016 12:43:49 GMT -5
Last attempt...JJ E34L
Closest I have but still about 10mA off...
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Post by gtrjunior on Jul 18, 2016 12:46:27 GMT -5
Trying half power...I'm assuming I should flip the switch(half power switch) before biasing...
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Post by gtrjunior on Jul 18, 2016 12:52:21 GMT -5
Ok...I pulled the 2 outer tubes and re-checked the bias on the inner 2. The one closest to output tranny read 34mA and the other is showing the same...plate voltage holding at 470...I'm gonna fire her up and see how she sounds.
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Post by gtrjunior on Jul 18, 2016 12:54:19 GMT -5
Hang on...forgot to cut the ohms in half
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Post by gtrjunior on Jul 18, 2016 12:56:21 GMT -5
Same readings
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Post by gtrjunior on Jul 18, 2016 13:35:12 GMT -5
Ok...successful bias!!! I didn't have to change the bias for half power as it was right where I set it earlier. I did discover one microphonic preamp tube....my telefunken. Too bad too because it's such a sweet tube. I replaced it with a NOS Tung sol which still sounded pretty killer. So I have a bunch of EL34's that will have to be kept as spares because I don't think they will bias correctly. They're readings were way off but hey may just get me through a gig in an emergency. Or hey may be fine for my JCM 800. Splawndude....bro, thank you for your help!! You're a knowledgable guy with his stuff! I'm glad I did this bias and it worked out! It really is a simple process...nothing to be afraid of
Btw...when I first checked he stock tubes they were biased way cold...about 25mA at 470vdc...I have to assume there was some kind of drift from the factory....maybe that's why I was having the volume fluctuations?
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Post by gtrjunior on Jul 18, 2016 13:36:39 GMT -5
Now to tackle the fx loop issue...I'm assuming it's one of my pedals.
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Post by splawndude on Jul 18, 2016 14:58:21 GMT -5
Ok...successful bias!!! I didn't have to change the bias for half power as it was right where I set it earlier. I did discover one microphonic preamp tube....my telefunken. Too bad too because it's such a sweet tube. I replaced it with a NOS Tung sol which still sounded pretty killer. So I have a bunch of EL34's that will have to be kept as spares because I don't think they will bias correctly. They're readings were way off but hey may just get me through a gig in an emergency. Or hey may be fine for my JCM 800. Splawndude....bro, thank you for your help!! You're a knowledgable guy with his stuff! I'm glad I did this bias and it worked out! It really is a simple process...nothing to be afraid of Btw...when I first checked he stock tubes they were biased way cold...about 25mA at 470vdc...I have to assume there was some kind of drift from the factory....maybe that's why I was having the volume fluctuations? Congrats! Good feeling right? Yeah - it is pretty simple when you boil it down. Thanks for you comments. Glad to help any way that I can. And yes, the bias will drift down like that over time. Try half power for awhile and see what you think. I tried it and liked it so much I stayed there. Saves on tubes too.
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Post by gtrjunior on Jul 18, 2016 15:11:44 GMT -5
Yes, it does give you a great sense of accomplishment!! My JCM 800 is a 50watter and I love it! I'm not opposed to running in half power at all!! It may just be in my head but it feels like the Drop B+ had a greater effect in half power...?? Idk
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Post by gtrjunior on Jul 19, 2016 13:05:13 GMT -5
So I played my QR for about an hour and a half today....it sounded killer-no volume fluctuations so I'm hoping that it was just due to a really cold bias. I also had a chance to look at my fx loop issues. Basically, I just removed everything form the loop and took my time putting it back together, making sure I thought out all the connections. So far it seems to be working perfect! No squealing in bypass mode...ill give it some more time before I declare the problem fixed but it's looking good so far.
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Post by TheFight on Jul 19, 2016 13:34:55 GMT -5
All sounds like good news!
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Post by Tempest on Jul 19, 2016 13:55:40 GMT -5
So I played my QR for about an hour and a half today....it sounded killer-no volume fluctuations so I'm hoping that it was just due to a really cold bias. I also had a chance to look at my fx loop issues. Basically, I just removed everything form the loop and took my time putting it back together, making sure I thought out all the connections. So far it seems to be working perfect! No squealing in bypass mode...ill give it some more time before I declare the problem fixed but it's looking good so far. Cool, hopefully it was just something random with the pedals....good luck!
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Post by gtrjunior on Jul 19, 2016 15:03:17 GMT -5
I'm keeping m fingers crossed...
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Post by splawndude on Jul 19, 2016 15:36:02 GMT -5
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Post by marcor on Jul 19, 2016 17:14:52 GMT -5
I'm keeping m fingers crossed... The metallic sound you recorded in your video sounded like something I noticed once when my loop was too hot for my Decimator G-String pedal.
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