PRS MT15 - Biasing

In this video we show how to set the biasing on the PRS MT 15 head and what you need to do so.

[@scottmoore8565]

Great and useful video..... It's like watching Edison work.... thx for the vid..... this continues a trend of Users being more helpful than manufacturers......

[@digitalreign7485]

Cheers! Thanks for the kind words. Glad it was useful and helpful.

[@vulgarchaos]

Did it yesterday, makes a big difference and it was supper easy thanks to your video!! Chhers mate!

[@digitalreign7485]

Cheers!

[@jasonmcmillan4373]

I'm so thankful for your MT15 videos. I've felt that mine wasn't quite right somehow ever since I got it. I'm gonna check this out now, and see if I can get some improvement out of it. Thanks!

[@digitalreign7485]

Glad to help Jason. I’ll keep the videos coming and I have ordered an MT15 with the 5881 power tubes. These are, in my opinion, the best amps for club gigs that I have played. Especially for the price tag. Cheers!

[@nathanielroy5086]

Mine always seemed to lack something also. After seeing this I bought a multimeter on Amazon and checked mine, it was off so I ajusted it to around 31, and I changed the V1 tube. Boy did that little tweaking make huge improvement. Now I get full low end and saturated tones like I couldn't before. This is a must do.

[@atte2038]

@@nathanielroy5086 Got mine today and plucked it straight into my marshall 1936 amp and got nothing more than a crunch. Im so frustrated because I waited 8 months to get that amp and now it seems I need an od pedal even though I thought it would be chuggy without.

[@jasonmcmillan4373]

@@atte2038 Man this is EXACTLY my issue. And my shared disappointment. Gonna follow through on what Nathaniel here says he did when I get to it. In the meantime if you have noise/hissing issues on the gain channel, order one of the cheap JHS 'Black Box' volume controls for the FX loop. Hissing gone, and proper control of that ridiculously sensitive master volume knob.

[@scentia_est]

​@@nathanielroy5086which tube did you put in instead?

[@GabrielGomes]

I'm here to say thanks AGAIN, my MT-15 is once more needing a valve swap and you're my go-to video! Cheer man!

[@digitalreign7485]

Thanks for the kind words. It truly is why I enjoy making these videos. Cheers!

[@BB-xn1rw]

Just got this head and have been watching your vids, ty !

[@digitalreign7485]

Thanks for tuning in. Cheers!

[@MegaChorro123]

Your channel is a life saver!!! thank you for this vid!!! Definitely looking forward to swapping my tubes and bias on my own MT-15. Have had it for almost two years and it’s definitely time to freshen it up!

[@digitalreign7485]

Fantastic. Glad to hear it. This is exactly why I made this series of videos. Let me know how you like the new tube combos with it properly biased! Cheers.

[@greenwave792]

yep, very cool bro. keep up the good work. its hard to find down to earth people my age on yt, i found you, keep going.... I bought this amp over a blues jr. for one reason, some days i wake up in a bad mood and there is nothing i can do about that, so when i'm in a mood, thats what comes out when i play. i'm getting so tired of chemo and hospitals...this amp has given me hope again. i go from journey to anthrax at the flick of a switch.....

[@digitalreign7485]

Thanks Greenwave! I appreciate the kind words. Sorry to hear about your health problems. I hope you’re on the road to recovery. Music is the greatest instrument for healing. Cheers!

[@CensuTaRozina]

thank you , mine were 22 /23 from factory .. hope this tubes will last ! :)

[@digitalreign7485]

Your welcome. Happy to help! Cheers

[@BB-xn1rw]

Did you have it ok full power / volume?

[@chryzis8322]

Great Video! Im about to change Tubes and do that by myself for the first time, so your Video is be very helpful!

[@digitalreign7485]

Much appreciated. Best of luck with the tube swap!

[@grunge113]

Thank you, man!! Keep on rocking!! 🤘🏼

[@digitalreign7485]

You bet. Thanks for watching!

[@mikedwiles]

Thanks for this informative video. Greatly appreciate it! One question, I noticed that the amp was in the low power mode while doing the bias check. I assume it doesn't matter as it is a dummy load similar to a speaker load. Thanks so much!

[@digitalreign7485]

Appreciate you noticing. I will post a follow up video to see if it makes a difference. Cheers Mike!

[@Dearco]

It does matter! Change to full power and make the Bias again. Your tubes will appreciate

[@roba7737]

I agree. It's disadvantagious to have your heart stop beating. That's a really bad day. 😂😂

[@markolivares6943]

Thank you for this. Very informative

[@digitalreign7485]

You are very welcome. Thanks for watching!

[@JayBruceWorld]

Amazing video brother! I’ve just ordered the new version with 5881 tubes. Do you think I could swap them out with 6L6 tubes?

[@ericzeng318]

Thank you for sharing this! Really helpful. Do you happen to know how to change a 220V MT15 into 110V? I heard that you can do that by just rewiring one connection?

[@SoDawn3]

5:40 Literally watching this on a sunday :0

[@skydemon02]

I watched it on a Friday 5 months later :(

[@TarshishedCactus]

I think I should be fine if I bias but my Mt15 came with 5881s. Could I put 6l6s in and bias?

[@digitalreign7485]

Hey Sean. Yes you will be fine. The 5881’s use a lower plate voltage than the 6l6 tubes so when you replace them the amp will be biased cold for the 6l6’s. Do you like the sound of the 5881’s?

[@TarshishedCactus]

@@digitalreign7485 They definitely sound good but I would like to try some 6l6s. Also thanks you very much!

[@masternapster5473]

thank you for the tutorial, helpful a lot ;)

[@digitalreign7485]

You bet. Cheers!

[@nicholaskname7735]

I suggest the bias be adjusted with the amplifier set to full power.

[@Alfgunnarp]

What values should 5881 tubes be biased to?

[@digitalreign7485]

Manual still recommends setting the around 30mV. However, you can adjust from that value +/- 5mV. Depending on if you want them running hotter or colder. Caution, running them at say 35mV will reduce the life of the tubes. But if it is the sound you are after. Then all in the name of Rock n Roll! Cheers!

[@Alfgunnarp]

@@digitalreign7485 Thank you!

[@GabrielGomes]

Thanks for this!!

[@digitalreign7485]

Thanks Gabriel! Cheers.

[@nickrooney6206]

So if I bought this amp all I have to do is go around the back and turn each bias up to close to 29 and it’s gonna crank louder heavier and harder .. then Stock ??

[@digitalreign7485]

Good one Nick! No magic elixir for pure guitar talent and practice. Just biasing the amp properly will keep it from overcooking your power tubes and needed them replaced sooner than you should need to. Cheers bud!

[@tilperose]

Did you have your amp on a play mode or standby mode when you adjusting the bias?

[@digitalreign7485]

I had with standby turned off or in regular play mode to emulate true playing conditions

[@digitalreign7485]

@@kirkhochburger8247 Much appreciated Kirk!

[@AJC-jo3ds]

Do you also check readings in lead channel , very helpful by the way.. thank you for this!!

[@digitalreign7485]

I did feel the need since the red channel effects the gain staging not the power section. So it shouldn’t matter which channel you bias. However, I will test this theory out and see if they are truly the same. Thanks!

[@AJC-jo3ds]

Awesome! Which 6L6 version did you go with? The 6L6GC? Thx!

[@666tonsofsquirrels]

Thanks, bud 🤘🤘

[@miladshahbazi9968]

thanks for the information

[@digitalreign7485]

You bet Milad. Cheers!

[@mr.howard1]

Skip to 6.00 to see biasing.

[@Zhorellski]

Any Octal tubes works on this Amp?

[@digitalreign7485]

Hey Zhorell. I made a follow up video that somewhat answers your question. I currently would only recommend 6L6 or 5881 tubes for the MT15

[@erpringle]

@@digitalreign7485 el34's will work I believe. Just make sure to rebias.

[@stephenbarton2625]

Thank you so much!!!!!

[@digitalreign7485]

You bet Stephen. Cheers!

[@Y.S.777]

thanks man!

[@digitalreign7485]

You bet. Thanks for watching!

[@matthiashellmig8637]

My MT15 Sounds fantastic but i can only get a BIAS reading from one side. Does anyone has this problem too?

[@Greg25815]

Thx ... that's cool

[@digitalreign7485]

Glad you like it. Cheers!

[@randytinsley9402]

Good video but I would of put amp to full power. I believe you had it at half power.

[@digitalreign7485]

Good observation Randy. I made a follow up video and was able to show that you could bias it half or full power and it didn’t impact the dc voltage measurements. Cheers!

[@randytinsley9402]

@@digitalreign7485 ok cool I'm getting one of these amps soon. Thanks for vid and info

[@itsmechris14]

I thought you were making the output stronger, from 15watts to 30…..

[@digitalreign7485]

Hey Chris. No that would be swapping out the output transformer. If you did that and some folks have it could be a 50 watt amp. I don’t have any plans on doing so. It already is around 23 watts or so and is plenty load for the club gigs I am playing.

[@howardgillingham4763]

It's TINY, that's what she said

[@digitalreign7485]

Ha! Nice

[@Van020280]

Painful to watch and listen to but somewhat informative.

[@workdays8280]

I buy one of these amps cos of these other KZbin scammers. It's a complete Toy to my black face fender twin. Total Chinese junk. When U turn a true valve amp up. They create a better sound .but this amp only gets louder. These other scammers on KZbin make it sound like a 100 watt mashall stack and very untrue

[@digitalreign7485]

Hey work days, For sure it is not a Fender Twin or a 100 watt Marshall and doesn't compare to the volume and wattage that those amp put out. What I think it is, and it's my opinion, is a very versatile, 6L6 power sectioned, 15 watt tube amp that is perfect for club gigs and recordings. It has the best tight bottom end tone out of any 15 watt amp I have ever played, with great clarity in high saturated gain tones and a serviceable clean tone somewhat reminiscent of a Fender for around $700 us dollars. Cheers!

[@erpringle]

@@digitalreign7485 I played a gig last night and the other guitar player was playing through a twin, and as far as sound goes, my little mt15 killed that twin. You only need so much power and the mt15 is the sweet spot for small clubs or even average sized clubs but if you're playing the collesium, yeah the more powerful twin is probably a better choice. I personally would rather have 2 or 3 mt15's than a twin and mic em. Not to mention the strain on the back carrying that monstrosity being the fender twin.

[@digitalreign7485]

Yeah I agree a twin for a small club is way overkill. I bet your MT15 mopped the floor over that Twin in that setting. At least you are able to get a bit of the power section working on your amp. That twin was probably set the volume at 1 or 1.5. Cheers!

[@TheLamboman640]

Dude, you talk about DC current and then say “we are testing for DC milliVOLTS” 🥴🥴

[@TheLamboman640]

Flathead, not a Philips dum dum