It is currently Mon Mar 16, 2020 5:25 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 129 posts ]  Go to page 1, 2, 3, 4, 5 ... 9  Next
Go to page 1, 2, 3, 4, 5 ... 9  Next
Author Message
Post subject: Super-Sonic 22 Bias Level
Posted: Wed Dec 01, 2010 8:04 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Dec 01, 2010 7:59 pm
Posts: 10
Does anyone know what the recommended level is for biasing the new Super-Sonic 22?

Would it be the same as the 65 Deluxe Reverb, since that is what the power section is based off of?


Top
Profile
Fender Play Winter Sale 2020
Post subject: SS bias
Posted: Thu Dec 02, 2010 9:12 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Hi iamsomewhere,

It depends on your Plate voltage and which output tubes that you have installed. Do you have the GT 6L6 that are the Sovtek 5881s? Those are 25 watt tubes, whereas some other 6L6 tubes are 30 watts. How are you checking the bias, with a probe or test points or how? :idea: Typically you want to bias the output tubes at 50% to 70% of their rating, depending on whether you want cleaner or more driven tone. Let me know; which tubes installed, method of checking bias, and Plate voltage. :)

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 10:11 am
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Jan 12, 2009 4:50 pm
Posts: 7998
Location: ʎɹʇunoɔ ǝsoɹ pןıʍ
I could be mistaken as I am not by any means an amp tech, just an amp snob, but I do believe the tubes in question are of the 6V6 variety and not the 6L6.

_________________
Image
Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 10:24 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
I gotta get that book for my new grand-daughter, B-man!

:mrgreen:

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 11:08 am
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Jan 12, 2009 4:50 pm
Posts: 7998
Location: ʎɹʇunoɔ ǝsoɹ pןıʍ
Retroverbial wrote:
I gotta get that book for my new grand-daughter, B-man!

:mrgreen:

Arjay


Oh, yah... It's a very good read for young and old alike!

:wink:

_________________
Image
Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 11:17 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
Can you e-mail me a bigger copy of that image?

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 11:56 am
Offline
Hobbyist
Hobbyist

Joined: Wed Dec 01, 2010 7:59 pm
Posts: 10
Quote:
I could be mistaken as I am not by any means an amp tech, just an amp snob, but I do believe the tubes in question are of the 6V6 variety and not the 6L6.


BMW-KTM is right. The tubes are 6V6's instead of 6L6's, just like the 65 DRRI. I don't have a probe or anything like that to check the plate voltage, but most people seem to think that a good setting is between 21ma to 25ma or so.

Fender seems to ship them out fairly cool (around 17ma), but I wasn't sure the settings for the 65 DDRI applied to the SS 22 as well.


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 1:15 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
iamsomewhere wrote:
...The tubes are 6V6's instead of 6L6's, ... I don't have a probe or anything like that to check the plate voltage,...


You need to know the Plate voltage in order to set the bias accurately. But, if you don't have a meter anyway, .... it doesn't matter because you can't tell how many mA your tubes are running. :?:

For example, at 330 Plate volts the 6V6 should run at about 23 mA each tube. At 400 Plate volts the 6V6 should run at about 19 mA each tube. You will have to have a meter in order to even know where the bias is now, or to adjust it. The setting is about the idle wattage, which is the Plate current AND the Plate voltage multiplied together, you need to know both. :)

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 2:58 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Dec 01, 2010 7:59 pm
Posts: 10
Quote:
You need to know the Plate voltage in order to set the bias accurately... it doesn't matter because you can't tell how many mA your tubes are running.


I have a nice multimeter, will that do? I just don't have a tube/socket probe. I know with my Hot Rod Deluxe there is a test lead on the back (on the PCB) that lets you measure that, but I'm unfamiliar with the 65 DRRI/SS22 so I don't know if they are the same. Does anyone here know?


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 3:33 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Yes, a multimeter is all that I use. I hope that you have the schematic to make things easier. Warm up the amp first, then check the DC Plate voltage from ground (chassis) to one of the output transformer primary leads, it will be a blue or brown wire, either one will work, where it connects to the circuit board and record the voltage (should be hundreds of volts). Next, see if you have the same type of test point as you have on the HRDlx, and read the DC voltage from that point to ground and record the mV reading. You may have two test points, use only one to check/set your bias. The mV reading at the test point can be directly read as mA (current). So if you get a reading of 32 mV at the test point, that is 32 mA of Cathode current. The Plate current will be about 5 mA less than that, so subtract .005 from the .032, about 27 mA of Plate current in this case. Then multiply the Plate voltage by the Plate current to get the idle watts. The 6V6 is a 14 watt tube, so the bias should be between 7 watts and 10 watts idle dissipation, depending if you want the sound clean (7), or driven (10).

If you don't have the test point to measure the mV (Cathode current), then with the amp off and caps discharged, measure the resistance of one half of the output transformer (blue lead to red lead, or brown lead to red lead) and record the ohms reading. Then turn on and warm up the amp, then check the DC voltage across the same points that you measured the resistance and record the voltage reading. Then divide the voltage reading by the resistance reading and that will be the Plate current (mA). After an adjustment of the bias pot, the voltage across the transformer will change, measure it each time and recalculate your idle. Adjust to your preference. :)

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 3:56 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Dec 01, 2010 7:59 pm
Posts: 10
Holy crap... awesome reply! This is exactly what I was looking for. Thanks! I just need to see if I can get my hands on a schematic of the new Super-Sonic 22.

Side note - if I do need to discharge the capacitors to measure the resistance, what is the best (and safest) way to do so?


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 4:40 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Yeah, the only schematics that I could find were the 6L6 equipped SS amps, they show two test points, one for each output tube. Probably the safest way to discharge the caps is to use a couple of clip leads and a 5 watt 400 ohm or so resistor. With the amp off and unplugged from electricity, clip one lead of the resistor to the amp chassis, and the other lead of the resistor to the positive lead of the power supply caps, making sure that the resistor and clip leads don't touch anything else, it can get hot. Also make sure that there is no short circuit made by the leads or resistor, don't let them touch the chassis or your body, you don't want sparks. After connecting the resistor to each cap positive lead for a minute, remove the resistor and clip leads and measure the voltage on the caps, repeat if necessary. The voltage will never be zero, but less than 10 volts or so is ok.

If you have the test points on this amp for the Cathode current like the HRDlx has, there is no need to discharge the caps in order to check/set the bias. You only need to discharge the caps if you want to use the second method, where it is necessary to measure the resistance of the output transformer primary, or when otherwise working inside the amp. :)

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Post subject:
Posted: Thu Dec 02, 2010 6:14 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Jan 12, 2009 4:50 pm
Posts: 7998
Location: ʎɹʇunoɔ ǝsoɹ pןıʍ
Unfortunately that's the only size I have left after one of my hard disks (in a striping RAID array) suffered a fatal (read physical) crash. Using solid state drives now but much data was lost. Much data.

I feel the need ... (slap)
for speed!

_________________
Image
Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.


Top
Profile
Post subject:
Posted: Mon Dec 06, 2010 3:37 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Dec 01, 2010 7:59 pm
Posts: 10
So I snapped a few pics. I located what Im assuming to be the bias pot (first image, blue disc, center) and I'm trying to follow your instructions to find out the plate voltage, etc.

I don't know if you can tell, but in the second image, which of the transformer wires (coming up through the bottom of the casing) do I need to check with the multi-meter?

Image

Image[/img]


Top
Profile
Post subject:
Posted: Mon Dec 06, 2010 5:21 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Yeah, it is hard to tell from the pics, but that looks like the power transformer wires, but I do see a blue, brown and red wires in there. You want the output transformer primary wires (three wires), which are usually blue brown and red wires. The output transformer will have one of the primary wires coming from the DC power supply to the transformer (red wire), the other two primary wires (blue and brown) will connect to the output tubes (circuit board), and the transformer secondary wires (speaker out) connected to the speaker out jack, or connected to the speaker from the circuit board. If you could start at the speaker, and trace back to the transformer wires to identify which transformer is which, that might work. You may need the prints to know for sure which are which if the colors are different. Let me know if this helps any. :)

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 129 posts ]  Go to page 1, 2, 3, 4, 5 ... 9  Next
Go to page 1, 2, 3, 4, 5 ... 9  Next

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: