Ok, there are no explanations in video what mods realy do to the sound. I was qurious to understand that, so i checked by writing my observation here. They are not scientific, they are just my understanding. R25=2,5k>10k (max alowed resistor/greed stoper for filtering hight freq on power tube +); R20=470R/1M (input impedance ?); R18=1K5>2.5k (more clipping in first stage, less gain - relevant to taste, no + or -); c8=25u>1u (less bass, voicing like first "treble" input stage in big marshalls +); 100pf on pot pins ("treblle cap" - taste. better to be swichable); Remove R7, R9, and C13 swich to 470K (simplification and going to dark side - 470k greed stoper resistor cuts more hights than 220k. Highst are added by 100p, now removed my bigger ressistor/low pass filter. Funny combination). Remove R28, C14, C20, and C21/Install 56k in R28/Install .022uf Mallory 150 in C20 and C21/Install 270pf in C14 (arguable. The best values that resolve issues for hight gain stock marchall TMB voicing are in p1 amp from ax84 project. This is in order to keep stock pots but change TMP knees); Remove R14, 470p across R12=470k. This last mod adds gain and brithens the tone. Its the most relevant to the goal of brithening amp. R13=220k>150k (reduce gain on triode). R27=150R(?)>220R. Thiss lowers tresshold to power valve clipping, reduce autput power, make sound more on the dirty side, but, prolongs tube life. Increasing values of C3, C4, and C11 is for better filtering. Choke - more noise filtering.

Such killer little amps. I miss mine all the time. Now I rock an Origin 20 which is great, but there was something really special about those little Class 5's.

algorithm for the win. very cool!

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

I had one and want another but I think it needs a high low two knob eq

Skip to 6.00 to see biasing.

Clean are better, but not the overdrive

😂😂😂Sorry I'm laughing but you were supposed to drill your holes closer to each other to the middle so that the handle can pull up when you get your hand in when you lift it, i love what you did with the valves, i might try it in future but right now im over the moon with the standard sound, a demo of your sound with those two changed valves against the two old ones would be very appreciated

Thanks, bud 🤘🤘

Nice run down. Love both, I personally don't play out live so 5881s for me at home, a bit richer and smoother sonic spectrum. 👍

Rumble 500 all day. MB has an anemic tone.

Wow !! 👌 I've been watching a lot of videos of this type of build because I'm trying to do my first one and I must say this is the nicest looking one I seen yet good job brother 👍..... Maybe you can help me out with some info ..... Will I get the same look effect using mahogany body ?.... What grit sandpaper do you use before you burn it and after ?.... And do you apply any oil on top or after you burn it you sand it down and then you're done ? Any info you can give from my first bill would be much appreciated again before work

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!

HA!!!! The BASS-ment.......I get it 🤣🤣🤣🤣

Nice.

What gear and/or software did you use to make this?

My issue is different, the top mirror fell down 😮..help me

Argh! I have my opinion from listening to my spearkers...and my diminishing ears... However, I wanted your opinion. I liked the Mark. Not fond of any of the D.I. INPUT sounds compared to the mic'd sound.

Should have used a looper to record the parts and run everything from it for consistency.

I replaced my handle over a year ago. Worked out great.

Didn’t you know you could’ve just reversed your boss back plate?

Not a strong demonstration of the tones

Thanks, I run a rumble 500 with ext fender 1x15 cab,the mids and lows do the job,but the higher notes up the frets have a noticeable lack of sustain compared to valve amps.Using Fender jazz 2016?I think

Valdra la pena cambiar mi rumble 500 por el markbass mb58r cmd 102 pure ?

What’s the point garbage video without isolated track so was this a production video ? More than a TUBE sounding difference useless video

For the past 10 years I’ve been trying to get my hands on this set but always something has to come up… maybe my next paycheck. Love the video and BTW try the antiquity surf You’ll love them

Those things are addicting. Love em.

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

Are you experiencing any issues with shielding? Obviously the metal plate would do this job a lot better compared to plastic plates. Have you considered using some kind of shielding tape for the inside side application?

I only have one problem with this video you never showed any of the components you changed or what they were there for or why you changed them. Right before I watched your video I watched Brads video and he had a schematic and showed what the components like grid stopper resistors and bias caps. In your own words not very inspiring video

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

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

What values should 5881 tubes be biased to?

Just what I needed. Gotta baby them Japanese BOSS gems

Sounds like s***

I make my own plates for my boss pedals couldn’t be easier.

"you know what else is a sleeve and tip?"

i fucking love you stuart

ебанутся модификатор бля . привернул новую ручку и опа мод +1000 к звуку . very cool mod +1000 sound characteristic

This is pretty great. Thanks man.

Just got around to exchanging my JJ 5881s for some JJ 6l6GC tubes. Here’s my personal experience using my PRS MT15. I have a modified 50 watt version equipped with with a Heyboer 4k transformer. I played at stage volumes using my stock PRS Custom 24 driving a Mesa 4x12 with vintage 30s date coded 4-18-2000. Testing just using my ears. Running 1/2 power. Presence at 1:00. Clean Volume: 11:00. Dirty volume: little past 9:00 The 5881s across the board have a lot more forward mids a bit less compression. The low end is similar to the 6l6 for the cleans. I love the 5881s for the clean channel. Most notably, a little louder/headroom, and more mid forward. Stiffer in tone. A little breakup in tone particularly on the treble pickup. The red channel is overly excessive in the mid-mids frequencies. I could put the midrange knob at 0-9:00 but the tone would become more stiff sounding and feel wise it felt like I was trying to bend telephone wire. With the mids at noon-1:00, I had tons of forward mids. Too harsh to the ears. Overall, the 5881s are more mid rangy/forward, less bass resonance. Can’t really dial in the guttural rock/metal tones I’m hearing in my head. For the 6L6s: Holy shit what a night & day difference! Instantaneously, the feel totally changed on the amp for the better. Single notes don’t feel overly stiff. A little more compression across the spectrum and tons of low bass resonance! Cleans have deep throaty lows, smooth mids, and clear bell like trebles. Think blackface Twin Reverb! Very airy and rich in tone. A little volume drop-I had to dial up the Volume knob to about 1:00 but it’s no big deal still very loud. A little breakup in tone on the treble pickup. For the red channel, you can run everything at noon, gain at 10:00 and have the most brutal, modern Rectifier tone and then some! Massive tight bass response at 2:00. Mids at 1:00 have a perfect balance of scooped compression, but it still has a forward push without sounding harsh, spikey or overbearing. Trebles have brilliance and a tight sizzle but not harsh or shrill to the ear. It’s the “it”’factor. Flipping over to full power on the back of the amp. Totally mind blowing HUGE! 🤘🤘 The 6L6 is what this amp needs if you’re chasing that heavy rock, guttural metal tone and everything in between. If you’re looking for the Tremonti tone, this is the tube. The 5881s don’t hold a candle to these. Team 6l6s!! You’ll never go back!!

I see a 3D printing project in the near future :)

Great Job ! Very smart and usefull !I do think it's needed to see which channel is engaged under the foot ( with the amp on my back. 😅) So the job is done and well done. Remarque : Why don't you add a red led diode for the lead channel in the same way as the blue one ? Is it difficult ? I am not a spécialist but think you just have to spot the 15v supply when lead engaged...(and you got the stuff to make it ) That would be great yo have both blue ans red led included in the FS! Keep on modding that awesone amp, always interesting 😊 Thanks. François (Paris, France

nice

I liked the MarkBaas first time I listened but just listened again and now I am liking the Fender Rumble 500 best.

Comparing that MB to those fender’s should be illegal lol

My ears like fender Rumble 500

It is a complete MYTH that handling tubes with your bare oily fingers causes problems. Several respectable amp builders/designers and tube manufacturers have debunked it. I used to handle them with white gloves before I knew better. Touch the tubes all you want, the oils from your fingers do nothing to damage them.

There is a way to have an LED light up when the circuit is open (on the red channel). Ive done this to a few of my amps that were wired in the same way as the MT15. Basically you wire the LED in parallel with the switch so that when the circuit is closed, it’s shorting out the LED. The blue channel will be active and the LED will be off. When the circuit is open, the signal will travel through the LED and resistor causing the LED to turn on and the red channel to activate. I dont have an MT15 so I couldn’t tell you what value resistor to use, but you would need to use one that will be high enough to block the signal from activating the channel switching but low enough to light up the LED. So it just takes a bit of trial and error but it will work.

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