It is currently Mon Mar 16, 2020 11:09 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next
Go to page 1, 2  Next
Author Message
Post subject: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Fri Jan 17, 2014 3:15 pm
Offline
Hobbyist
Hobbyist

Joined: Sun Jun 14, 2009 4:42 am
Posts: 89
Location: Ontario, Canada
Hi everyone,
I just picked up a matched pair of M Boogie 6L6 GC power tubes.
I hit a doz stores & my choices were GT or Mesa (that's the only two they all carried)
I picked the Mesa as I already have stock GTubes.

I don't have the equip to figure out the plate rating so I was wondering if anyone using MB in their HR Dlx III have a safe bias level?

The tube labels are marked as follows, 10 AC YEL

any help would be greatly appreciated.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Fri Jan 17, 2014 3:54 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Bias them to usual 6L6GC standards. You need to know the specific anode plate voltage of your amp to set an accurate idle dissipation wattage. Most Mesa Boogie labeled 6L6GC's are relabeled Russian or Chinese made tubes. Just follow their typical data sheets.

http://www.tubebooks.org/tubedata/HB-3/ ... 6L6-GC.PDF


Top
Profile
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 2:03 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
beatles1909 wrote:
...I don't have the equip to figure out the plate rating....


6L6GC should be a 30 watt tube.

The Plate voltage will be approx 430 volts unless something is wrong with your amp. Assuming approx 430 Plate volts, set the bias to read between 75mV to 80 mV at the test point. If you can measure the mV at the test point, then you can also measure the V of the Plates. If you are using bias probes, set the bias to approx 38 mA to 40 mA per tube.

How are you going to measure the bias setting?

_________________
---> "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: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 2:24 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Sun Aug 05, 2012 9:50 am
Posts: 1399
shimmilou wrote:
beatles1909 wrote:
...I don't have the equip to figure out the plate rating....


6L6GC should be a 30 watt tube.

The Plate voltage will be approx 430 volts unless something is wrong with your amp. Assuming approx 430 Plate volts, set the bias to read between 75mV to 80 mV at the test point. If you can measure the mV at the test point, then you can also measure the V of the Plates. If you are using bias probes, set the bias to approx 38 mA to 40 mA per tube.

How are you going to measure the bias setting?


Question please. I have a HRDIII so approx. 430 volts is my plate voltage? What setting on a multi meter is used for measuring plate voltage and where does one put the probe?

I have TS 5881 tubes with a rating of 23 watts per tube. My current setting at the bias point is 65mV at pre use and 69mV after use. No sputtering, flames or burnt smells yet. :D

Sounds very smooth too. It will bark but not bite. :lol:

I am now taking notes on all this. Owning a 'real' tube amp is demanding me to be mire than a curious onlooker now. :shock:

_________________
I have some Fender gear.
(Telecaster, Jaguar, Villager 12 String. Mustang l, Bronco, SCX2, Rumble 350, HRDIII, Rumble 2x8 Neo Cab)
http://www.reverbnation.com/modwiz


Top
Profile
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 2:34 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
modwiz wrote:
Question please. I have a HRDIII so approx. 430 volts is my plate voltage? What setting on a multi meter is used for measuring plate voltage and where does one put the probe?


You'll be measuring DC voltage -- set your meter for the 1000-volt DC scale. If measuring at the tube socket, put the red probe on pin 3 and the black probe to chassis ground.

EXERCISE EXTREME CAUTION!

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: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 6:05 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
Retroverbial wrote:
...EXERCISE EXTREME CAUTION!...


+1!

Maybe a better place to check the Plate voltage is where the brown or blue wires from the output transformer (OT) primary connect to the board (referenced to the chassis). These two solder pads are farther away from other connections, not closely spaced as at the tube socket. Put the positive meter lead on either the blue or the brown wire solder pad, with the negative meter lead on the chassis. Each wire connects to pin 3 of each tube, and pin 3 is the Plate of each tube. In the bottom right of this picture, the brown and blue wires go over the front edge of the circuit board and connect underneath, and the solder pads are on the side of the board facing up. The two resistors on the solder side of the board are the screen grid resistors which I changed and mounted on that side for ease of installation, yours will be on the other side of the board.

Image

_________________
---> "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: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 6:31 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
modwiz wrote:
...Question please. I have a HRDIII so approx. 430 volts is my plate voltage? What setting on a multi meter is used for measuring plate voltage and where does one put the probe?

I have TS 5881 tubes with a rating of 23 watts per tube. My current setting at the bias point is 65mV at pre use and 69mV after use....


If your tubes are really only 23 watts, then your bias setting of 65 mV is just fine (that's about 60% of the tube's rating), and your Plate voltage might be a little more than 430 VDC. 430 is usually very close to actual, and can be a little higher or lower depending on tubes and bias setting, as the Plate voltage will change with change in bias setting.

_________________
---> "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: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 7:38 am
Offline
Hobbyist
Hobbyist

Joined: Sun Jun 14, 2009 4:42 am
Posts: 89
Location: Ontario, Canada
shimmilou wrote:
beatles1909 wrote:
...I don't have the equip to figure out the plate rating....


6L6GC should be a 30 watt tube.

The Plate voltage will be approx 430 volts unless something is wrong with your amp. Assuming approx 430 Plate volts, set the bias to read between 75mV to 80 mV at the test point. If you can measure the mV at the test point, then you can also measure the V of the Plates. If you are using bias probes, set the bias to approx 38 mA to 40 mA per tube.

How are you going to measure the bias setting?

I wasn't going to probe or anything as I am not ready for the morgue yet (I'm only 64) :D

I bought the book How To Hot Rod Your Fender Amp so far , so I am starting off slow.
Last week I replaced the pre amp tubes with 12at7 in V3 & 12ay7 in V2 & V1 but the Drive & more Drive cut out as if it was locked & I couldn't get it to switch so I put the 12ax7 back in V1 & V2 & all is fine now .

Secondly: the next day when I played (imitating Dick Dale) the reverb was very low in volume so I put the12ax7 back in V3 & the rev worked normally . The next day the reverb was way down in vol. again which is how it is now, It works but what 4 used to be is now turned up to 8 or so for the same sound. (does not get wet at all like before?)
The amp is only 4 weeks old so I thought better not mod anymore.


Top
Profile
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 7:58 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Sun Aug 05, 2012 9:50 am
Posts: 1399
Wow! Thanks to those who have so generously provided me with their time and information. It is well explained and easy for me to follow. :D

_________________
I have some Fender gear.
(Telecaster, Jaguar, Villager 12 String. Mustang l, Bronco, SCX2, Rumble 350, HRDIII, Rumble 2x8 Neo Cab)
http://www.reverbnation.com/modwiz


Top
Profile
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 9:22 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
beatles1909 wrote:
Secondly: the next day when I played (imitating Dick Dale) the reverb was very low in volume so I put the12ax7 back in V3 & the rev worked normally . The next day the reverb was way down in vol. again which is how it is now, It works but what 4 used to be is now turned up to 8 or so for the same sound. (does not get wet at all like before?)

The amp is only 4 weeks old so I thought better not mod anymore.


V3 has nothing to do with the reverb operation in your amp. The reverb driver/receiver are both solid state. If the reverb is not working properly, there is a problem in that circuit and you should take the amp back to the place of purchase for warranty repair/replacement.

_________________
Bill

Image


Top
Profile
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 9:25 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
modwiz wrote:
Wow! Thanks to those who have so generously provided me with their time and information. It is well explained and easy for me to follow. :D


Just buy a bias probe and quit mucking around with internal tests points. You are likely to do damage if a probe tip slips. Trust me, I know from experience.

viewtopic.php?f=13&t=88475

_________________
Bill

Image


Top
Profile
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 9:28 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
beatles1909 wrote:
Last week I replaced the pre amp tubes with 12at7 in V3 & 12ay7 in V2 & V1 but the Drive & more Drive cut out as if it was locked & I couldn't get it to switch so I put the 12ax7 back in V1 & V2 & all is fine now .


Using a 12AY7 in both V1 and V2 will make the Drive channel almost unusable. There is not enough gain with those two tubes to get much drive out of the amp without maxing out the controls. Use a 12AY7 or 5751 in V1 only and leave a 12AX7 in V2.

_________________
Bill

Image


Top
Profile
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 2:22 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
beatles1909 wrote:
shimmilou wrote:
beatles1909 wrote:
...I don't have the equip to figure out the plate rating....


...

How are you going to measure the bias setting?

I wasn't going to probe or anything as I am not ready for the morgue yet (I'm only 64) :D ...


Then you can't possibly set the bias, so I'm not sure why you asked about a bias setting if you are not going to check. :?

_________________
---> "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: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 2:36 pm
Offline
Hobbyist
Hobbyist

Joined: Sun Jun 14, 2009 4:42 am
Posts: 89
Location: Ontario, Canada
Then you can't possibly set the bias, so I'm not sure why you asked about a bias setting if you are not going to check. :?[/quote]



I thought all I needed was a plate level which is why I asked, so when I put the new Mesa tubes in I could just set the bias to the figure quoted to me earlier ei:70mv.
I will leave it alone until I learn more!
thanks for your help!


Last edited by beatles1909 on Sat Jan 18, 2014 2:36 pm, edited 1 time in total.

Top
Profile
Post subject: Re: Hot Rod Dlx III & Mesa 6l6gc bias question
Posted: Sat Jan 18, 2014 2:36 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Sun Aug 05, 2012 9:50 am
Posts: 1399
bluesky636 wrote:
beatles1909 wrote:
Last week I replaced the pre amp tubes with 12at7 in V3 & 12ay7 in V2 & V1 but the Drive & more Drive cut out as if it was locked & I couldn't get it to switch so I put the 12ax7 back in V1 & V2 & all is fine now .


Using a 12AY7 in both V1 and V2 will make the Drive channel almost unusable. There is not enough gain with those two tubes to get much drive out of the amp without maxing out the controls. Use a 12AY7 or 5751 in V1 only and leave a 12AX7 in V2.


That was what I thought. I must be learning something. :P

_________________
I have some Fender gear.
(Telecaster, Jaguar, Villager 12 String. Mustang l, Bronco, SCX2, Rumble 350, HRDIII, Rumble 2x8 Neo Cab)
http://www.reverbnation.com/modwiz


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next
Go to page 1, 2  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: