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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Sat Mar 26, 2011 12:46 pm
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Perfect! :)

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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Mon Apr 04, 2011 12:49 pm
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maybe for a new post, -
the new ss's are a head or 2-12 format and have a bias meter on the back and you can pull 2 of the 4 power tubes to knock it down to 50W/12W ( 1/4 power switch on back)

cool~!

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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Mon Apr 04, 2011 1:06 pm
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twirlyboggs wrote:
maybe for a new post, -
the new ss's are a head or 2-12 format and have a bias meter on the back and you can pull 2 of the 4 power tubes to knock it down to 50W/12W ( 1/4 power switch on back)

cool~!


The new Supersonic 100's are now listed on the product website -- both the combo version and the separate head/speaker cabs.

Looks promising.

Arjay

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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Mon Apr 04, 2011 2:34 pm
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twirlyboggs wrote:
maybe for a new post, -
the new ss's are a head or 2-12 format and have a bias meter on the back and you can pull 2 of the 4 power tubes to knock it down to 50W/12W ( 1/4 power switch on back)

cool~!



Super cool! Lots of new cool features!

But the weight! The combo weighs more than twice as much as my SS 22! :o
Not so strange that they have put wheels on it
:D


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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Mon Apr 04, 2011 2:40 pm
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It's a tube-fired, twin-twelve, 100-watt combo amp. It takes a minimum specific amount of iron, steel, copper, brass, etc to make those elements work in harmonious efficiency.

You can argue with your boss, you can argue with your mother-in-law, you can even argue with me.

But you cannot argue (and win) against the laws of physics.

Arjay

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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Mon Apr 04, 2011 3:24 pm
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Retroverbial wrote:
It's a tube-fired, twin-twelve, 100-watt combo amp. It takes a minimum specific amount of iron, steel, copper, brass, etc to make those elements work in harmonious efficiency.

You can argue with your boss, you can argue with your mother-in-law, you can even argue with me.

But you cannot argue (and win) against the laws of physics.

Arjay


I know, Retroverbial :D

But I am quite pleased that I don't need 100 watts tubeamp. The 22 watt I have is quite sufficient for my needs. And I do not have to had back pain.
But I would like to have had some new features. :)


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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Mon Apr 04, 2011 3:30 pm
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evg wrote:
But I am quite pleased that I don't need 100 watts tubeamp. The 22 watt I have is quite sufficient for my needs. And I do not have to had back pain.


+1

My DRRI is getting more stage use than my TR's for that very reason.

Rawk on!

Arjay

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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Sun Apr 24, 2011 8:45 pm
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Hello,

Will adjusting the bias level do something about white noise / buzz?

Thanks!


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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Sun Apr 24, 2011 11:16 pm
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No, I will not affect the hiss and buzz issues...


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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Fri Apr 29, 2011 9:59 am
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I just picked up my amp from the service center and there is a considerable drop in noise. The repair guy just applied the new Fender tech note regarding the reverb and decrease the bias level. There is still a little noise but not as much as before.


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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Fri Mar 30, 2012 6:11 pm
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Installed new tubes and biased mine this evening. Bias was set at 31mV, I set it at 24mV. It's an improvement in tone for sure.


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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Fri Jan 11, 2013 7:08 pm
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This thread has been super helpful. It has given me the confidence to bias my SS22 - just ordered the power tubes. Sounds like I need to (to briefly sum up):

1. check the plate voltage just to make sure I'm around the 415 standard
2. check the voltage of each tube and shoot for 24 mV

This video mentions also setting the "Bias control voltage".
http://www.youtube.com/watch?v=19IUadZJf-c

I know its for a DeVille but I just want to be sure I'm not missing something. He makes the following comment:

There are two voltages being measured / monitored here. The first voltage is the bias control voltage. Start the biasing procedure with the bias control voltage at its highest NEGATIVE voltage in this case -60V. This voltage is measured at the edge of the blue pot. Turn the blue pot until this voltage is close to -60V. The second voltage is measured at the test point. This voltage is a representation of the current flowing in the tube. This voltage should be adjusted by the blue pot to 60mV.


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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Fri Jan 11, 2013 9:45 pm
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Plate voltage and bias current are interactive. As one goes up the other goes down. You adjust the bias current (by measuring the voltage at the test point) and set it to what you want. The plate voltage is what it is. No guarantee that it will be 415 VDC. You multiply the bias current by the plate voltage to get the idle plate power dissipation. That number should be between 50% and 70% of the maximum plate dissipation which is 14 watts for a 6V6GT type tube.

Setting the bias power supply voltage to -60 VDC initially only guarantees that you don't burn the tubes up when you first apply power. The voltage at the test point is the critical value. Once that is set the voltage at the power supply will most lkely be something different from -60 VDC.

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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Mon Jan 14, 2013 9:02 am
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Thanks Bill! So it sounds like your saying I need to take my plate voltage measurement in order to know where to set my bias optimally. I can use a calculator like this to do that:

http://www.webervst.com/tubes1/calcbias.htm

And as far as making any adjustments I just need to worry about the test points and setting my bias to the number I come up with based on my plate voltage.
Right?

If any of the original posters are around - I'm wondering then how the bias setting of 24 mA / mV was arrived at? The Weber calculator is coming up with 20.2 and I though that was for 70%.

Thanks!


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Post subject: Re: Super-Sonic 22 Bias Level
Posted: Mon Jan 14, 2013 10:17 am
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Try the 6V6GTA instead of just 6V6, from the pull down menu for tube type, this should give you 23.6 mA, round up to 24. Most 6V6 are 14 watt tubes, and apparently the Weber calculator considers a 6V6 as a 12 watt tube, although I think that just about all 6V6 since the metal cans are rated 14 watts, and some are rated a little more.

This is another reason to learn the math yourself and avoid dependance on some misinterpretation of a tubes watt rating. You can find spec sheets, or ask the supplier for the watt rating of the tube.

Max Plate watt dissipation rating times desired percentage of idle, divided by Plate volts equals Plate current. In the case of a 14 watt tube with 415 Plate volts, (14 x 0.7)/415 = 23.6. Typically, choose 50% to 70% for the idle bias, so use 0.5 to 0.7 as your multiplier. In order to be accurate, it is best to always check your Plate voltage with a meter and not to assume that it is as the schematic lists. Note that changing the bias adjustment will also affect the Plate voltage, so after any adjustment, recheck and make sure that your numbers are still close to your desired idle wattage.

In most cases the test point in an amp is going to be on the Cathode of the output tube, and the reading will be the Cathode current. The Cathode current is close enough to the Plate current to allow interchanging of the two numbers. In the case of the SS 22, there are two test points, one for each output tube. Be aware that some amps share one test point for two output tubes, so the Cathode current reading at the test point in that case should be divided by two to get the number for one tube.

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