HT Stage 100 MK11 Bias LEDS

Discussion - HT Venue amplifiers. Inspiration from Studio to Stage.
Adders
Posts: 2
Joined: Sat Mar 23, 2019 1:54 pm

Mon Mar 25, 2019 7:46 pm

The Blackstar HT Stage 100 head has the new feature for easy tube biasing, LEDs for bias adjustment and balance using PR1 and PR2

Checked mine today and works well, adjust until green LED goes out before Red LED comes on simple !!

Nice feature Blackstar, possible bias adjustment without removing from Head shell

brianwrym
Posts: 15
Joined: Wed Sep 23, 2015 5:24 pm

Thu Jun 06, 2019 4:10 pm

Hello,

I was wondering about that.. I see 2 green lights back there... so you are saying to adjust the bias until both dont show green?

Is there any information out there about this feature or is it in the manual?

Also, by doing the bias this way, do you know what the tubes are being biased to in milliamps or other?

Thanks!

Brian R.

brianwrym
Posts: 15
Joined: Wed Sep 23, 2015 5:24 pm

Thu Jun 06, 2019 6:36 pm

Hello,

By doing the bias according to the above (Getting both pots between green and red, amp on and off standby with a guitar cable in the input jack with the main master off) the led's stay off until I start playing... when I play heavy chords on od1 I see the right led goes into red and the left on will slightly go into red. Is this normal behavior?

I backed off both posts to where when playing the led's stay off so im curious if there is any official blackstar recommendations?

Noiseaddicted
Posts: 2
Joined: Mon Jun 03, 2019 10:46 pm

Wed Jul 03, 2019 3:16 am

brianwrym wrote:
Thu Jun 06, 2019 6:36 pm
Hello,

By doing the bias according to the above (Getting both pots between green and red, amp on and off standby with a guitar cable in the input jack with the main master off) the led's stay off until I start playing... when I play heavy chords on od1 I see the right led goes into red and the left on will slightly go into red. Is this normal behavior?

I backed off both posts to where when playing the led's stay off so im curious if there is any official blackstar recommendations?
This happens on mine as well, I think it just indicates that you are right on the dividing line. The 100 mkii sounds fabulous at this bias setting IMHO, SOOOOOOO much better than the factory preset... Saturated, chunky, sonic paradise!

Harley9599
Posts: 3
Joined: Sun Feb 02, 2020 5:28 pm

Mon Feb 03, 2020 5:58 pm

Is there any way that one of you guys can explain it to me in layman's terms exactly step by step. You go about biasing this amp. There's two screws I believe one's for balance and ones for the bias am I correct, or is each screw for each individual light?

brianwrym
Posts: 15
Joined: Wed Sep 23, 2015 5:24 pm

Tue Feb 04, 2020 3:51 pm

Harley9599 wrote:
Mon Feb 03, 2020 5:58 pm
Is there any way that one of you guys can explain it to me in layman's terms exactly step by step. You go about biasing this amp. There's two screws I believe one's for balance and ones for the bias am I correct, or is each screw for each individual light?

Hello,

Basically on the back of the amp you have 2 pots and 2 Leds.... The pot on the right is for power tube bias, the one on left is for power tube power balance. have the amp connected to the speaker cab, turn on the amp, set all the master volumes to 0 and make sure a guitar cable is plugged into the input jack. Turn the amp on and turn off the standby to play mode and let it sit for a while (say 5 mins at least) to get the tubes warmed up.

Adjust the left pot until it reaches green on the led. Then adjust the right pot until it goes green. If by changing one the other led goes into red, go back and fourth until both get to green. If for some reason the tubes wont bias and balance into green then perhaps the tubes are drifting in current draw (Basically going bad) and you may need to replace the tubes with a matched set.

I found more info on this forum page, but its essentially the same thing :
https://www.blackstaramps.com/forum/vie ... =28&t=7176

Thanks

brianwrym
Posts: 15
Joined: Wed Sep 23, 2015 5:24 pm

Wed Feb 05, 2020 4:52 am

Im just going to leave this here, enjoy :)


Blackstar HT VENUE MkII BIASING

LED method:
1) From rear of amp/chassis, locate the two round BIAS and BALANCE trim pot holes and
four small rectangle slots near to the power valves.
2) Identify each: The set of holes nearest the power valves are for the BALANCE trim pot
and LED’s. The other set of holes are for the BIAS trim pot and LED’s. Round hole for
trim pots, rectangle slots for LED’s.
3) Set the BALANCE and BIAS pots to minimum/anti-clockwise.
4) Install valves, if not already done.
5) Connect amp to load (speaker) and put dummy jack or guitar lead into INPUT.
6) Set all Volumes including Master to minimum.
7) Turn amp On and in Standby. Let it warm up for a minute or two.
8) Switch to fully On, still with Master at minimum. Both Green LED’s should be lit.
9) Turn the BIAS trim pot until the corresponding green LED goes out and before the red
LED comes on.
10)Now adjust the BALANCE trim pot until the corresponding green LED goes out and
before the red LED comes on.
11)Re-adjust BIAS trim pot if necessary to keep both corresponding LED’s off.
12)Re-adjust the BALANCE trim pot if necessary to keep both corresponding LED’s off.
Internal voltage measurement method:
1) From rear of amp/chassis, locate the two round bias/balance trim pot holes and
identify each as above.
2) Set the BALANCE pot approx. in the middle. Set the BIAS pot to minimum/anticlockwise.
3) Locate the main bias test point, TP13, on the main PCB.
4) Connect a Digital Volt Meter (DVM) set to 200mV range as follows: Black lead to
chassis, Red lead to TP13. (It can be clipped to the leg of D7 that is connected to TP13.)
5) Connect amp to load (speaker) and put dummy jack or guitar lead into INPUT.
6) Set all Volumes including Master to minimum.
7) Turn amp On and in Standby. Let it warm up for a minute or two.
8) Switch to fully on, still with Master at minimum.
9) Turn the BIAS trim pot while observing the DVM reading:-
10)For 40/50/60 watt models set the BIAS trim pot for a DVM reading of 50mV (+/- 2mV)
11)For 100 watt models set the BIAS trim pot for a DVM reading of 100mV (+/- 5mV)
12)Now adjust the BALANCE trim pot to make both corresponding LED’s go out as
described in LED method above. Alternatively this can be tuned by ear by connecting
the output to a speaker and adjusting the BALANCE for the lowest hum.
13) Repeat points 10 to 12 until both the BIAS and BALANCE are optimised.

maico996
Posts: 5
Joined: Mon Dec 09, 2019 8:22 pm

Mon Feb 10, 2020 6:43 pm

brianwrym wrote:
Wed Feb 05, 2020 4:52 am
Im just going to leave this here, enjoy :)


Blackstar HT VENUE MkII BIASING

LED method:
1) From rear of amp/chassis, locate the two round BIAS and BALANCE trim pot holes and
four small rectangle slots near to the power valves.
2) Identify each: The set of holes nearest the power valves are for the BALANCE trim pot
and LED’s. The other set of holes are for the BIAS trim pot and LED’s. Round hole for
trim pots, rectangle slots for LED’s.
3) Set the BALANCE and BIAS pots to minimum/anti-clockwise.
4) Install valves, if not already done.
5) Connect amp to load (speaker) and put dummy jack or guitar lead into INPUT.
6) Set all Volumes including Master to minimum.
7) Turn amp On and in Standby. Let it warm up for a minute or two.
8) Switch to fully On, still with Master at minimum. Both Green LED’s should be lit.
9) Turn the BIAS trim pot until the corresponding green LED goes out and before the red
LED comes on.
10)Now adjust the BALANCE trim pot until the corresponding green LED goes out and
before the red LED comes on.
11)Re-adjust BIAS trim pot if necessary to keep both corresponding LED’s off.
12)Re-adjust the BALANCE trim pot if necessary to keep both corresponding LED’s off.
Internal voltage measurement method:
1) From rear of amp/chassis, locate the two round bias/balance trim pot holes and
identify each as above.
2) Set the BALANCE pot approx. in the middle. Set the BIAS pot to minimum/anticlockwise.
3) Locate the main bias test point, TP13, on the main PCB.
4) Connect a Digital Volt Meter (DVM) set to 200mV range as follows: Black lead to
chassis, Red lead to TP13. (It can be clipped to the leg of D7 that is connected to TP13.)
5) Connect amp to load (speaker) and put dummy jack or guitar lead into INPUT.
6) Set all Volumes including Master to minimum.
7) Turn amp On and in Standby. Let it warm up for a minute or two.
8) Switch to fully on, still with Master at minimum.
9) Turn the BIAS trim pot while observing the DVM reading:-
10)For 40/50/60 watt models set the BIAS trim pot for a DVM reading of 50mV (+/- 2mV)
11)For 100 watt models set the BIAS trim pot for a DVM reading of 100mV (+/- 5mV)
12)Now adjust the BALANCE trim pot to make both corresponding LED’s go out as
described in LED method above. Alternatively this can be tuned by ear by connecting
the output to a speaker and adjusting the BALANCE for the lowest hum.
13) Repeat points 10 to 12 until both the BIAS and BALANCE are optimised.
Where did you get this information?

Harley9599
Posts: 3
Joined: Sun Feb 02, 2020 5:28 pm

Fri Feb 14, 2020 10:05 pm

I appreciate the help fellows you save me a lot of money 👍 it was so easy a caveman could do it 🤷‍♂️

brianwrym
Posts: 15
Joined: Wed Sep 23, 2015 5:24 pm

Sat Feb 15, 2020 1:44 am

maico996 wrote:
Mon Feb 10, 2020 6:43 pm
brianwrym wrote:
Wed Feb 05, 2020 4:52 am
Im just going to leave this here, enjoy :)


Blackstar HT VENUE MkII BIASING

LED method:
1) From rear of amp/chassis, locate the two round BIAS and BALANCE trim pot holes and
four small rectangle slots near to the power valves.
2) Identify each: The set of holes nearest the power valves are for the BALANCE trim pot
and LED’s. The other set of holes are for the BIAS trim pot and LED’s. Round hole for
trim pots, rectangle slots for LED’s.
3) Set the BALANCE and BIAS pots to minimum/anti-clockwise.
4) Install valves, if not already done.
5) Connect amp to load (speaker) and put dummy jack or guitar lead into INPUT.
6) Set all Volumes including Master to minimum.
7) Turn amp On and in Standby. Let it warm up for a minute or two.
8) Switch to fully On, still with Master at minimum. Both Green LED’s should be lit.
9) Turn the BIAS trim pot until the corresponding green LED goes out and before the red
LED comes on.
10)Now adjust the BALANCE trim pot until the corresponding green LED goes out and
before the red LED comes on.
11)Re-adjust BIAS trim pot if necessary to keep both corresponding LED’s off.
12)Re-adjust the BALANCE trim pot if necessary to keep both corresponding LED’s off.
Internal voltage measurement method:
1) From rear of amp/chassis, locate the two round bias/balance trim pot holes and
identify each as above.
2) Set the BALANCE pot approx. in the middle. Set the BIAS pot to minimum/anticlockwise.
3) Locate the main bias test point, TP13, on the main PCB.
4) Connect a Digital Volt Meter (DVM) set to 200mV range as follows: Black lead to
chassis, Red lead to TP13. (It can be clipped to the leg of D7 that is connected to TP13.)
5) Connect amp to load (speaker) and put dummy jack or guitar lead into INPUT.
6) Set all Volumes including Master to minimum.
7) Turn amp On and in Standby. Let it warm up for a minute or two.
8) Switch to fully on, still with Master at minimum.
9) Turn the BIAS trim pot while observing the DVM reading:-
10)For 40/50/60 watt models set the BIAS trim pot for a DVM reading of 50mV (+/- 2mV)
11)For 100 watt models set the BIAS trim pot for a DVM reading of 100mV (+/- 5mV)
12)Now adjust the BALANCE trim pot to make both corresponding LED’s go out as
described in LED method above. Alternatively this can be tuned by ear by connecting
the output to a speaker and adjusting the BALANCE for the lowest hum.
13) Repeat points 10 to 12 until both the BIAS and BALANCE are optimised.
Where did you get this information?
I dont give sources, but its from a a reliable source. I donot see anywhere any instructions on how to service this amp and its mind boggling that they would not show in the user manual what the LEDS do.

I know this doesnt answer the question, but at least I can help folks out.

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