Marshall Master Volume Mod Test / Comparison 

I gotta say, I really like your vids, Kley. I get to finally understand concepts that most other sources tend to explain very poorly... thanks!

Hi Kley, I installed the same mod in my lemmy style amplifiers and I simply added a 5K potentiometer in series, so fine-tuning even works up to bedroom level : )

Awesome well done video Kley! Love how you explained the technical part then went to the sound clips back to back like that, awesome! To me the PostPI Master volume sounded best for sure on the Plexi circuit. Interesting side note for me was that people always say that some versions of Master Volumes sound bad which I had never experienced until I played around with the MV on my 5E3 build. I had originally done the Post Phase inverter MV on it and it never really sounded right when the amp distorted, I was not a fan. I decide to change it to Rob Robinettes PrePhase Inverter MV and the amp now sounds glorious and like I hoped a Tweed would sound cranked but at bedroom levels. Just goes to show that each circuit will respond to different MV's and now I see why some can sound bad..you just need to find the right one for the circuit! Keep the videos coming Brother, love the channel!

Hello, Im glad to see your new video.

hi klay, thanks for the video! I vastly prefer the #3 over the factory #4 , and I'm looking forward to putting the #3 in my amp!

Great video! I'm going to try that on my JTM50 clone. Its biblically loud so needs some taming

I think the weird taper effect is because you’re actually adding a resistor in parallel to the 220k (or 100k) which are carrying the bias voltage to the power tube grids. So, those fixed resistor are modifying the taper of the pot they’re now in parallel to. Also, this approach reduces the effective value of those resistors, which form an RC high pass passive filter together with the preceding decoupling caps, the more so the more you lower your volume. As a consequence, you’re not reducing only volume, you’re also reducing bass (which is in fact audible in your comparison clips). So, keep this in mind!

Great video! The way I see it and the way the post inverter master volume works, maybe it would be nice to try a linear pot. "Normal" volume controls are changing the db so it makes sense to use audio pots, no matter if it's a guitar, pedal or amp, but since this master molume works as a mixer, it should probably work more smoothly with a linear pot. Please try it and make a vomparison video if it isn't much of a fuss!

great resource, thanks!

Great video, and having both pre and post is a great idea. As you have shown, though, unfortunately, Type 3 has a limited window of where it really works, generally, it doesn't do much in the middle range. If you want full range, it's best to go with the Lar-Mar as a Post PI. Keep up the great vids

Very informative, Thanks!!

On the type 3, I like to use a switchable 250k pot. Pull for the master volume and push in and it’s out of the circuit. Lar mar master so far is my favorite, have not tried the rich mod II master yet.

Dude, working on a marshall 1987 clone. This is just what i needed. By the way has anybody ever told you you look like Will Forte?

Nice!!!

I'm wanting to mod my JTM50 build to Friedman DS40 spec after hearing one. It's basically a JCM800 preamp with a JTM power section. The thing I'm wondering about is by adding a master will I lose some of the character of the original? I have always been under the impression that non-master volume amps have different gain structure. The DS40 just sounds killer though. Also wondering if it's possible to do a master volume version of the mod or have a push pull switch that takes the MV out of the circuit.

I am going to put a type 3 in a bassman build. I live in an apartment so I need bedroom levels. Does type 3 work well from 0 to 1 or 2? Or does it spike up to fairly loud quickly. Thanks for any feedback. Pun intended! And great content btw !!

Now that is a coincidence. I had just installed this mod, in the amp that I am currently building, and then saw that you had posted this video. My conclusions on my bench were similar to yours. The mod works great except the the sweep is funky. Most of the attenuation occurs at the end of the travel. To try to fix this I did some experimenting; I tried a liner 500k, audio 500k, audio 250K and reverse 500K. The liner made the problem much worse, as it "fell off the cliff, at the end. The others didn't solve the problem either and also made it worse. Unfortunately, deductive reasoning, and "book learning," are disagreeing with this quandary. My experimentation suggests that I need a higher value pot, like 2M, which I don't have right now, but "theory" dictates that the problem is the taper. I guess that I need to order a few pots and see what I can come up with. If you find a solution to the problem, please let me know.

What is the humbucker in your bridge pickup?? I love it. Sounds nice and responsive not too much high end. Great playing btw!

I dont know what value you're using, but to remove the effect of the Type 3 master volume you have to disconect it! even a 1Meg pot will kill a bit o signal.

Why is your mouth moving all weird when playing?