Hi! Very interesting! I have one and my sound fluctuate.. Do you know what's going wrong? I change both tubes and i have the same problem. Thanks for your time!!
in the video, around 6:00 you advise to attach the ground on the multimeter to the case ground. am i correct in understanding that to be just any piece of metal on the chassis of the amp?
@@MusicAndWood thanks for the swift reply. i have a mkii ht5r combo at home that i'm hoping will have a similar process to this when it comes time to change the tubes
Thank you for the informative video. I've had this amp for almost nine years. Today, it got suddenly volume down to almost silent level. And after a power reboot, sound started waving as if somebody turns up and down the volume pot. I think, the tubes (idk which one, maybe both) had completed their missions. Needs to be changed, i guess. Before i change them, i was curious about how you find the 46 mV value. Or, what if i change the 12AX7 with equivalent tubes such as 12AY7 or 12UA7 , what would be the voltage on test point?
I didn't see you measure cathode voltage drop or plate voltage so like I'm wondering how you know the plate dissipation in watts ? How have you got it biased and at what %
Loved this video, as an aspiring electronics hobbyist, I have a few questions though, how did you arrive at the 46mV bias set point? And also in regards to the balancing is it possible to run through this procedure (as in taking measurements and adjusting as opposed to listening for hum) as it was skipped over?
Thanks for this Very informative, and easy to follow video. My son just bought an HT5 combo amp, with a 10" speaker, and reverb. Would it have the same chassis as the one in this video? If yes, he would also have to adjust the bias as you show in this video, correct? I've read forum posts that state these are auto biasing amps. I also contacted Korg customer service and they basically would not tell me. Hoping you can clear this up for me. Thanks again.
Yes the chassis should be the same. It depends on if it is a first gen or MK II as to if they would be different. If you are going to replace the tubes swap them out let it warm up and then take a reading. You may or may not need to adjust the bias. If I recall correctly you will want to see about 46 mv across the test points. Certainly be very careful in the chassis when plugged in and on, very high risk of shock if you touch the wrong things. The safest bet is always to take it to a tech.
@@MusicAndWood Thanks again for info. And yes, it is a first Gen HT5. Just realized that you and I have something in common; I too am musician and wood worker.😁
Great video! I have a question about the balance adjustment. What does it technically do? Is there a measurement involved or do you adjust this by ear?
Thanks ! You can measure it to be exact. It balances the two triodes on the tube. The test points tp6 and tp7 voltages should match, use the balance pot to adjust them.
Hello friend, I have a question, I have the same amp, it started to sound slow and distorted on the clean channel, but the overdrive channel when activated sounds good, do you think it could be the tube? And if so, which of the 2 would it be?
Good evening, I have a BLACKSTAR HT-5RH MKII head to which I have changed the tubes with a 12AX7EH gold pins as the preamp and a 12BH7 AEH gold pins in the power stage. I really want to learn how to adjust the bias but I don't know the mV values on which to set my BIAS trimmer or on which resistance and cathode to perform the measurement. Could you help me? thank you, I am grateful to you. Simone.
Honestly I don't know why this head ships with 12ax7. Almost all the other compatible 9 pin tubes sound better in it. Try a 12ay7 in the preamp. Makes it a whole new amp and tames the harshness of the od channel. Gain knob becomes usable at any level and sounds great which was this amps weak point before. Clean channel loses chimey-ness but has way more punch because you can really crank it. Add a tube screamer up front on the od channel with the gain rolled back and the volume cranked and get great hard rock and metal tones. A 12ua7 in the pre turns it into a great blues amp and all the knobs become super responsive. For 15 dollars it's worth experimenting with different pre tubes.
Hi i have discovered this on mine,combo version,if you connect directly in the return,it s completly loss volume and tone regolation on both channel,volume and tone is controlled now from pedals and guitar,i am an not at all a techinician but the solution could be add a master volume
Great video! Worked prefectly on my gen I combo as well.
Glad it helped ! Thanks for the watch and comment, it is great to hear how my videos are of help!
Great video…changed the tubes and biased exactly as you showed in the video and I now have a correctly biased happily singing HT5h! Many thanks!
Awesome, thanks for the watch and comment !!
Hi! Very interesting! I have one and my sound fluctuate.. Do you know what's going wrong? I change both tubes and i have the same problem. Thanks for your time!!
Recently bought a mkii version of this amp and although I have no intention of messing round inside it, I enjoyed the learning experience.
Hello, thank you for the watch and comment ! When the time comes around to change the tubes you will know how now :)
thanks for the info. i had just purchase this amp head and looking forward to retube and re bias the amp. great explanation and clear instructions!
Glad it was helpful! Congratulations on a great purchase!
in the video, around 6:00 you advise to attach the ground on the multimeter to the case ground. am i correct in understanding that to be just any piece of metal on the chassis of the amp?
That is correct indeed.
@@MusicAndWood thanks for the swift reply. i have a mkii ht5r combo at home that i'm hoping will have a similar process to this when it comes time to change the tubes
@@tatertotter25 Should be pretty easy to get those tubes updated, be safe and good luck!
@@MusicAndWood this may be a silly question: do I need to measure ac or dc voltage? I’m assuming dc but I’m not sure
You should be measuring DC voltage. Be very careful as there is high voltage in there too!
Very good ! Thanks
Thank you for the informative video.
I've had this amp for almost nine years. Today, it got suddenly volume down to almost silent level. And after a power reboot, sound started waving as if somebody turns up and down the volume pot. I think, the tubes (idk which one, maybe both) had completed their missions. Needs to be changed, i guess.
Before i change them, i was curious about how you find the 46 mV value. Or, what if i change the 12AX7 with equivalent tubes such as 12AY7 or 12UA7 , what would be the voltage on test point?
Did you have to make those balancing on your amp after replacing the tubes?
Hi! I have the same problem vith my volume. Mine has 15 years old. Do you know how to fix this problem? Thanks!
Hello, what good information, I have a question, what voltage are the 2 transformers?
I didn't see you measure cathode voltage drop or plate voltage so like I'm wondering how you know the plate dissipation in watts ?
How have you got it biased and at what %
Loved this video, as an aspiring electronics hobbyist, I have a few questions though, how did you arrive at the 46mV bias set point?
And also in regards to the balancing is it possible to run through this procedure (as in taking measurements and adjusting as opposed to listening for hum) as it was skipped over?
For combo ht5 amplifier, is the measurement the same?
I believe so
Thanks for this Very informative, and easy to follow video. My son just bought an HT5 combo amp, with a 10" speaker, and reverb. Would it have the same chassis as the one in this video? If yes, he would also have to adjust the bias as you show in this video, correct? I've read forum posts that state these are auto biasing amps. I also contacted Korg customer service and they basically would not tell me. Hoping you can clear this up for me. Thanks again.
Yes the chassis should be the same. It depends on if it is a first gen or MK II as to if they would be different. If you are going to replace the tubes swap them out let it warm up and then take a reading. You may or may not need to adjust the bias. If I recall correctly you will want to see about 46 mv across the test points. Certainly be very careful in the chassis when plugged in and on, very high risk of shock if you touch the wrong things. The safest bet is always to take it to a tech.
@@MusicAndWood Thanks again for info. And yes, it is a first Gen HT5. Just realized that you and I have something in common; I too am musician and wood worker.😁
Great video! I have a question about the balance adjustment. What does it technically do? Is there a measurement involved or do you adjust this by ear?
Thanks ! You can measure it to be exact. It balances the two triodes on the tube. The test points tp6 and tp7 voltages should match, use the balance pot to adjust them.
Hi! I have one of the original HT5's (no reverb) Do you know if the layout is the same as that in the demo!
Thanks for the video.
Very welcome, glad it was helpful!
@@MusicAndWood It was helpful a lot. Thanks.
Hello friend, I have a question, I have the same amp, it started to sound slow and distorted on the clean channel, but the overdrive channel when activated sounds good, do you think it could be the tube? And if so, which of the 2 would it be?
Sounds like a tube problem
Good evening, I have a BLACKSTAR HT-5RH MKII head to which I have changed the tubes with a 12AX7EH gold pins as the preamp and a 12BH7 AEH gold pins in the power stage. I really want to learn how to adjust the bias but I don't know the mV values on which to set my BIAS trimmer or on which resistance and cathode to perform the measurement. Could you help me? thank you, I am grateful to you. Simone.
How do you know the bias should be 46mV?
Honestly I don't know why this head ships with 12ax7. Almost all the other compatible 9 pin tubes sound better in it. Try a 12ay7 in the preamp. Makes it a whole new amp and tames the harshness of the od channel. Gain knob becomes usable at any level and sounds great which was this amps weak point before. Clean channel loses chimey-ness but has way more punch because you can really crank it. Add a tube screamer up front on the od channel with the gain rolled back and the volume cranked and get great hard rock and metal tones. A 12ua7 in the pre turns it into a great blues amp and all the knobs become super responsive. For 15 dollars it's worth experimenting with different pre tubes.
Great tip indeed. I was thinking about trying something other than the 12ax7
How to bias a BLACKSTAR HTSTAGE100?
B+ voltage very important.
70% from Wa tube. ( datasheet )
Why didn't you clean the sockets with the old or the new tubes and some contact cleaner ?
It's a legitimate question.
Hey, thanks for the watch and question. Didn’t seem necessary but sure wouldn’t have hurt. Next time I am in there I might do that.
Hi i have discovered this on mine,combo version,if you connect directly in the return,it s completly loss volume and tone regolation on both channel,volume and tone is controlled now from pedals and guitar,i am an not at all a techinician but the solution could be add a master volume
I thought those didn't need for bias adjustment? Thanks for the video!