Adding a master volume to the Marshall Class 5

[Searcy]

I have owned a lot of tube amps over the years. Currently I own three and yet they never seem to be my go to amps. The reason is simple. By the time I have cranked the amp up enough to get the sound I like out of it it's to loud for the other people in the house. Even on the small 5 watt amps I've owned there is enough power to rattle the windows by the time the tubes are breaking up just right. In an effort to address this I have looked at using attenuators and was very close to trying to build one when I stumbled across some information about a mod that could be done to a Marshall Class 5. What you do is install a Variable Voltage Resistor which reduces the DC voltage powering the valves, allowing them to overload at lower volume. Since one of my current amps is a Marshall Class 5 and the kit to do this mod was less than $40 I decided to give that a try.

 

 

 

Ok... it's time to dig into the Class5 Marshall again. I ordered the VVR kit from Hall Amplification which I'm going to add as a bit of a master volume.

 

Here is a video of how they are installed.

 

http://www.youtube.com/watch?v=xV0g3VW_Vfc

[Searcy]

The guts of this amp are easy to get too. That's nice.

 

 

[krock]

I agree with you on that it gets too loud when you want to set it to a desirable tone. I had to use pedals when I borrowed one from a friend to test in my living room because it didnt break up early enough. I cant remember which company made them, but I remember seeing a speaker with a built in attenuator. If its actually as good as a stand alone then its a good idea. The gut shots cool, never realised how simple it was (and tidy)

[PingPongBob]

I had a master volume added to one of my Class 5 heads a few months ago.

 

 

Don't know how it was done, but it only cost me $40.00. I'm very happy with the results.

[Izzy]

Searcy, you're damn right about having to go high on tube amps before you get the desired sound...I do not like distortion pedals and I often thought using them would be the only choice if I wanted distortion at lower volumes (I refuse to use a D pedal on a tube amp, it feels wrong).

 

I have settled for cranking the amp all the way up and using my guitar at low volume...that distorts at reasonable volumes, though not as much as I'd like and only if I have my guitar set right.

 

I want to know if this worked for you, if it gave you the desired effect. An attenuator you say...hmmm.

[surfpup]

(I refuse to use a D pedal on a tube amp, it feels wrong)

 

To each his (or her) own. I generally set my tube amps (and I've owned dozens) for a nice warm "Wind Cries Mary" tone - rich and tubey but not yet distorted - and let my pedals do the rest. It helps obviously to have good sounding pedals, but I get a lot more cool tones this way... overdrive, fuzz, boost... the possibilities are endless and great sounding.

 

In fact with regards to the OP, I've owned the Class 5 head and it only sounded good with pedals. It's own cranked sounded was pretty crappy. And yes, I tried adding a master volume. It's still gone.

 

As for attenuators, if you are lowering the gain more than about 6db it's gonna thin out and sound anemic.

[Searcy]

The kits can be bought here..Hall VVR kits They are very reasonable and can be used on most tube amps. I'd say the skill level to put this one in is medium. You need to be able to find and brake your B+ power and so on. I had to hit up my friend Dave Mac to help me out with some pointers. He has used this kit on his own amp and had a very cool blog about the whole thing...

 

Dave Mac's Killer Guitar Blog

 

 

 

So the first things to figure out is where to put the new knob so that it looks good. PingPong I like yours but I decided to locate my parts a little differently. I'll show ya tomorrow.

[RaysEpiphone]

Well, ok but this sort of defeats the original design of the amp. I'll just use my Marshall Jackhammer stomp-box.

[Izzy]

Well, ok but this sort of defeats the original design of the amp. I'll just use my Marshall Jackhammer stomp-box.

 

Are you talking about the issue Surfpup brought up? "Thinning" the sound?

[RaysEpiphone]

Are you talking about the issue Surfpup brought up? "Thinning" the sound?

Umm, sort of. I'd say if you want an amp with a Master just buy one with a Master.

[badbluesplayer]

Umm, sort of. I'd say if you want an amp with a Master just buy one with a Master.

Yeah, but the Class5 doesn't have a master volume, so he's putting one in there.

[badbluesplayer]

I had to sell my Class 5 for some reason. They're great amps. I'm really curious about this type of master volume vs. the regular old "stick a pot in before the power section" type of master volume.

[Searcy]

I've owned the Class 5 head and it only sounded good with pedals. It's own cranked sounded was pretty crappy.

 

No, I really like the sound of the amp. That's why I bought it. I just would like to get that cranked tone at lower volumes.

 

Well, ok but this sort of defeats the original design of the amp. I'll just use my Marshall Jackhammer stomp-box.

 

That's the point is to defeat the original design. The original design doesn't have a master volume.

 

I've tried a few stomp boxes on it and some of them sound good. The Jack Hammer wasn't one of them though. Had to get rid of that pedal. The Govnr isn't bad though.

 

I'd say if you want an amp with a Master just buy one with a Master.

 

Ummmm, I don't think you guys understand what we're doing here. All that being done to the amp is we are adding the capability to lower the B+ voltage on an amp whose sound I do like. When the pot is set at 10 the voltage will be running as stock. Will it sound great when it's done? I don't really know. That's why I spent that $35 and that's why I'm doing the mod. To learn. If it turns out great I'll be adding this set up to my other tube amps. If not then I won't waste my time. But to be honest, my good friend Dave Mac who knows me, knows my amps and guitars and knows how to build a great amp says it's worth it so I expect it is.

 

When it's done I'll record some video and you can all decide for yourselves.

 

 

After some pondering I decided to move the power light over next to the input jack and install the new pot where the power light had been. Sort of the opposite of PingPongs set up.

 

 

This is an easy move to make.

 

 

Cut the zip ties that hole the wires and unplug it from the board.

 

 

Pull off the hot glue that holds the retaining ring from rattling.

 

 

Then you have to carefully but forcefully wiggle the lamp out of the hole and the ring.

 

Finally drill a hole in the amp next to the jack...

 

...and reinstall the lamp. The wires will just reach.

[badbluesplayer]

I like the master volume location there where the light was, more like the usual order of knobs. Even thought it isn't in the signal path at the end like a normal master volume.

[Riffster]

Cool mod Searcy, look forward to the sound clips.

 

I have the itch to buy a Marshall Class 5 head but I don't think it will do anything than my Mesa doesn't already do. Still if I run into one at an exceptional price I may jump on it.

 

To each his (or her) own. I generally set my tube amps (and I've owned dozens) for a nice warm "Wind Cries Mary" tone - rich and tubey but not yet distorted - and let my pedals do the rest. It helps obviously to have good sounding pedals, but I get a lot more cool tones this way... overdrive, fuzz, boost... the possibilities are endless and great sounding.

 

This.

 

My Mesa and Marshall both have master volumes but my Vox and Fender don't, I set those to the point they will have breakup and then add a fuzz, overdrive or even a my compressor pedal.

 

The thing is to successfully marry a pedal into the sound and dynamics of your amp, the pedal needs to actually push the amp, if it isn't then you are just listening to your pedal through a tubeified signal path.

[Searcy]

Ok, now it's time to mount the Hall VVR kit in the amp. The MOSFET chip has to be mounted so that the heat sink can work properly. That means bolting it to the chassis. So I dry fit everything and mark where the hole for the MOSFET bolt will need to be.

 

Then drill the hole...

 

 

Before mounting everything we need to attach three wires to the VVR board. We do it now because it would be damn tricky to do later.

 

Green is B+ out

Yellow is B+ in

White is ground

 

Now we can mount the MOSFET to the chassis. MAKE SURE TO USE THE PROVIDED PLASTIC SHIELD between the MOSFET and the chassis.

 

Then install the board and pot.

 

Tighten it all down.

 

Now solder the MOSFET legs into the board.

 

 

The last step will be to break the B+ and rout it through the VVR and hook up the ground wire.

[Searcy]

So let's ground the sucker first.

 

 

Just crimp a screw lug to the end of the white wire and attach it to the amps chassis ground lug.

 

Now... It's time to insert the VVR into the B+ power of the amp.

 

 

With this Marshall Class5 it's not to tricky. First locate the R6 resistor. See that green thing above the headphone jack? Congratulations!! You just found R6.

 

 

Now... pay attention!! You have to be sure to cut the resister leg on the right RIGHT!! right and leave enough there to attach wires to each side.

 

Sorry the picture is crap but that's me cutting the right resister leg. It's plenty long enough. Cut it about 1/4" above the board so you'll have a little meat there to attach the green (B+ out) wire to the board side. The Yellow wire (B+ in) is soldered to the bit of the leg that's left on the resistor.

 

 

I bent the resistor up so that it wouldn't short out on anything. It's funky looking but that's how it's done. I may slide some shrink wrap over the resister before calling it finished.

 

 

Now.... fire it up and ROCK!!! but very quietly #036; #036;

[Searcy]

 

Still need to score me a cool Marshall knob like PingPong has but I think it's cool and very effective. Video coming soon.

[PingPongBob]

I got a feeling yours is going to sound a lot better than mine.

 

Thanks for posting Searcy.

 

I'm going to print this thread and take it to my guitar/electronics guy.

 

I want this done to my other Class 5 head.

[krock]

Very interesting guide you've added since I last checked this thread. Looking forward to the sound clips

[badbluesplayer]

How's it sound?

[Searcy]

How's it sound?

 

 

The playing is a bit sloppy but you get the idea.

 

^^^^^Video demo^^^^^

[surfpup]

Sounds good

[badbluesplayer]

Yes - Sounds really good!

[manse]

Hard to come to a judgement without being able to hear the real volume in the room - but it certainly seemed to turn down the overall volume a significant amount and to maintain the cranked tone.... good work!! (And great to have all the pics and then the demo. Thanks.)

Manse