Any drawbacks of non-master-volume amps?

King IzzO))) · Apr 21, 2015

Re: Any drawbacks of non-master-volume amps?

Is it possible to place a switchable, fully bypassed MV circuit in there? Surely someone has done that.

zzmoore · Apr 21, 2015

Re: Any drawbacks of non-master-volume amps?

By-pass what.?
And what with...a switch and wires that add as much resistance and capacitance as the the MV does.?
While you are at it, why not bypass the pre volume too. If the MV Pot is a bad idea, the Preamp Volume Pot must be equally as bad...right.?
There seems to be some prejudice against a MV Pot. Maybe because it is often added to an amp as an after thought.?
Yeah, it CAN be done poorly.
But done properly, I do not see what the problem is.....and I am speaking as a guy that does not "like" a MV.....I rarely put one in an amp I build, but I build (typically) 20 Watt, and under, amps.
I can see where a "loud" amp wold benefit from a MV.
Maybe it is the way it is used.? Sure, if you crank the preamp, and add just a bit of MV, the amp will sound "bad".....horses for courses.
I still cannot imagine a guy would ever (in a blind test) be able to hear the difference in the same amp, if you could A/B between the Non-MV and the MV version, with the MV on "10".
I don't know.......

King IzzO))) · Apr 21, 2015

Re: Any drawbacks of non-master-volume amps?

That makes sense. I know jack **** when it comes to amp design, I was just asking.

Chickenwings · Apr 22, 2015

Re: Any drawbacks of non-master-volume amps?

fwiw i have been using a master volume JTM clone type amp for the last six months as a gigging amp in all kinds of settings from small clubs to outdoor festival gigs. The amp itself has probably done around 40-50 gigs in that time. Many moons ago i also used various modern style high gain type marshall half stacks.
I actually never set the master volume anywhere near full out. To be honest i don't think the amp sounds any better after a certain point on the master volume. In fact all it does is get looser and looser, and at that point it is drowning out the drummer and the rest of the band anyway.
I know it goes against the general consensus of the "purists" that have such strong views on what the perfect way to achieve guitar tone is, but while i love my old fenders with no mv, i would not even consider rolling up to a gig with no master volume on a marshall. There are just too many times that not being able to pull down your volume makes an amp unuseable. It is only rare that you can play super loud, and even if you can, it doesn't mean you should. I mean, even if you are on a big outdoor stage with multi thousand watt PA systems, what is the point in being so loud that you cant hear the rest of your band onstage? Master volumes are a good thing because you can get a great sound and the kind of touch response we all like at whatever volume level the gig dictates.
Re: attenuators. Nothing in audio is transparent. They change your tone just as much as, or even more so than a lot of MV circuits. Plus they weigh a lot and you end up cooking your power tubes fast.

Forget the purists. Keep it simple. Get a master volume. You wont be sorry, you'll have a great sounding gigging and recording workhorse. You can still always crank it up to 10 if you need to.

Chickenwings · Apr 22, 2015

Re: Any drawbacks of non-master-volume amps?

oh yeah one last thing....those old marshalls were rated conservatively at 30 watts.
The thing is....the way old jim rated his amps was the wattage achieved viewed on the oscilloscope before any distortion or clipping on the wave. So in reality, a 30 watt amp such as the JTM is only running at 30 watts before you hear any clipping at all. The actual wattage and output of an amp like that when its feeling nice and warm and smooth to play, not even necessarily crunching hard is often a lot higher than the rating. Depending on the tubes (whether you go for kt66s or el34s) you can squeeze upwards of 50 watts out.
Remembering that even a fairly moderately inefficient speaker like a greenback can put out 97db with only 1 watt of power, running a pair of them, or a quad or possibly even more efficient speakers and you are talking really loud. Loud, like too loud for your band let alone the audience.
Last time i played a nmv marshall it was a 50 watt jcm800. Goddamn. Loose fillings in my jaw - even when the volume knob said things were under control! lol

Archer250 · Apr 22, 2015

Re: Any drawbacks of non-master-volume amps?

Talked to the maker. Apparently, he made quite a bit of modifications to the output, the power section, the transformers and all... so I MIGHT be able to talk him into building me a MV version of the sound I'm looking for

Thanks, guys. I'll definitely try to keep it realistic as possible.

LLL · Apr 22, 2015

Re: Any drawbacks of non-master-volume amps?

What you need for slaving:

- A dummy load
- A line out box
- A 2nd amp

For example, the dummy load + line out box could be a THD HotPlate (has both).

Or it could be a THD HotPlate + line out box such as a Suhr ISO Line Out.

A 2nd amp could be even an EHX .44 Magnum stompbox-sized power amp.

Or could be any amp sitting around.

The basic chain as follows (including FX "loop"):

guitar
|
1st amp (speaker out 1) --> dummy load
| (speaker out 2)
line out
|
FX
|
2nd amp
|
speaker

Here's a vid I made which explains the process: