How do you adjust bias on Fender Super Champ XD?

[Zackb911]

I've tried googling, BillM's site, and searching youtube but no luck. I have some new Tung Sol 6v6GT's coming Monday and I'd like to check and adjust the biad but can't find any specifications or instructions, anyone know where I can?

Thanks!

[thejerk]

See here. It's easy-peasy!

http://www.agileguitarforum.com/view...d=11815&page=1

[Zackb911]

Just what I needed thanks!

[Wally]

zach, 'easy peasy' as long as you heed the warning that is in that linked post....deadly voltages.

[Joey]

Use a bias probe. It's safer/easier and you don't need to pull the chassis out of the amp to get at the bias points. You can get one for about $35 from Eurotubes.

[Wally]

Is that bias adjustment pot accessibale from outside the chassis?

[Billm]

The bias pot is not accessible from outside the chassis, so a bias probe is just another way to wear out your sockets. You've got to pull the chassis. It's easy.

[Wally]

Bill, Just so I cna understand things.....
That tutorial in the link states that the reading at that test point needs to be divided by 2 to get the current draw per tube. IS that resistor shared by both power tubes? OR is the tutorial incorrect? I am accustomed to halving the reading in 4 power tube situations but not in two power tube amps????

[Billm]

Yes, it's a shared 1 ohm resistor, so you read 40mV to get 20mA per (hopefully matched) tube. Obviously, you could get individual readings with a bias probe, but you can't do anything about it other than swap tubes for a pair that's better matched.

[Wally]

Thanks, Bill.

[czech-one-2]

Just biased my new super champ,[and added a dvm probe receptacle on the rear panel for easy future readings] I was surprised to find that r20 was giving me a reading of 16mv!
I upped it to 40mv and the amp got much louder and a little warmer too.
Before it was extremely chimey and sparkly,not very loud and kinda hissy,but I still liked the amp.However I am prefering the added volume and warmth [especially in channel 2]and quieter operation since adjusting the bias.
I'd like to see others stock bias settings,cause mine was WAYoff of the 40mv mark.
Another surprising finding,I hooked it up to a 1x12'' cabinet with a weber cali in it,and I think I prefer the stock speaker to the weber! Probably wasnt pushing the weber hard enough.
So now I 'm trying to decide on a replacement 10'' that would be more efficient and loud,without drastically changing the stock speakers fendery tone.I've read that the rajin cajun can be too warm,[and I dont want to loose any more sparkle,] but others swear by it. I'm not a fan of celestion or british speakers in fender amps,so its down to a jensen neo,
Jensen p10Q,weber 10f150,eminence common wealth,or an old alnico silver dust cap eminence 70w speaker .

[dqami]

anybody have the new link or can direct me to another site on how to bias the amp as Agile has changed their website so the old link doesn't work

[fstempleton]

Try here:
http://www.archive.agileguitarforum.....php?tid=11815

[Hiker]

Take your time, and with everything unplugged, and turned off, cushion any parts to protect them, or the tolex covering on the amp.

And remember, some are cold biased, and some are hot biased-from the factory!

Have fun!

[dqami]

Thanks!

[Scott57]

I'm about to bias an amp (Super Champ XD) for the first time and the instructions in the link seem quite clear. I do have one question, though about the picture used: is there any reason for the arrow pointing to Pin 7? Is there anything I have to know or do about that point?

[t-luxe]

No. There is nothing you need to do involving pin 7 to bias the amp.

[Scott57]

Originally Posted by t-luxe

No. There is nothing you need to do involving pin 7 to bias the amp.

Thanks! I didn't think so and suspected that a pre-existing photo was used to show the bias points but wanted to make sure I wasn't missing something obvious since I'm new to this.

[FenderGuitarFan]

I am not trying to change the path of this thread, but I do have a question (and Lord knows I have asked enough of you all recently!!).

I have been doing some reading on this and it sounds like the SCXD can come cold-biased from the factory. If I get a brand new one in the box, should I check this before I even start playing through it? I am wondering if this has been the issue with a couple that I have tried recently. They had a pretty noticeable hiss going on and just didn't sound like the videos. On one of Don Anderson's youtube videos, someone comented that their amp did not sound like Don's until they biased it. (I realize that other factors like playing ability and guitars need to be taken into account as well.)


Thanks in advance,
Jim

[Billm]

Hiss is usually a bad/weak tube or too-hot bias. I would suspect the 12AX7 and check the bias.