PPI Master Volume or Power Scaling?

[leadfootdriver]

I'm about to do a new build. I'd like to limit the overall volume for in the house playing.

PPIMV seems to be pretty popular right now, but I'd like to be able to bypass it. That said, would it sound better to just scale the power section?

What are your experiences?

[big_teee]

I'm about to do a new build. I'd like to limit the overall volume for in the house playing.

PPIMV seems to be pretty popular right now, but I'd like to be able to bypass it. That said, would it sound better to just scale the power section?

What are your experiences?

I am using the Lar/Mar PPIMV with 250k Double Pot.
when You turn the volume all the way up it is more or less bypassed.
The Resitance is similar to having the 220k resistors in place.
Lar/Mar PPI-MV - MetroAmp Wiki
Good luck,
Terry

[jmaf]

If you add two more capacitors on the output of the master volume you can decouple the bias from the volume control, avoiding the risk you mentioned.

[imaradiostar]

Both. Power scaling will cause output tube distortion at lower volume.

On some designs you'll be distorting the power section long before the preamp when you're scaled to low voltages. Fix that balance by scaling only the output section and using a PPIMV.

I'm pretty sure Kevin and others address this- google search it.

jamie

[Chuck H]

Anything you do that reduces volume will change the tone. A PPIMV will keep the power tubes from adding their particular character to the tone. Power scaling will alter the gain balance of the stages and change the voltage conditions that give the tubes a particular tone and also effect sag characteristics. An attenuator will alter the load such that kickback voltages and OT characteristics are somewhat nulled making the overdrive feel less dynamic.

Point is that nothing is ideal and every player needs to find a compromise offends their particular tastes the least. Lesser of evils as it were.

Imaradiostar has it right with the combination of power scaling and a PPIMV. That or an attenuator. Attenuators are more bulky than other circuits and an active load attenuator even more so. I build a simple resisive attenuator into my amps under 50 watts. It works very well for trimming volume without detriment to the tone to a point. At bedroom levels there is a notable difference. An active load helps but as I mentioned is bulky as well as expensive (relatively).

The actual electrical characteristics of circuits that lower volume are also compounded by the fact that loud simply sounds different than quiet. Some will argue that the speaker and cabinet just don't sound the same at lower volumes. And they're right. Also, your ears don't HEAR the same at lower volumes as at higher volumes. (see Fletcher Munson curves, Google).

In light of all this it would be best if you could sample every option and choose the one you like best (or dislike least). Since this is impractical I would say just do whatever offers you the ease of operation you want.

Sometimes the easiest thing to do is just accept that there will be a difference in tone at lower volumes no matter what. So build the amp you want without extra circuits and use a pedal for low volume practice.

FWIW high gain preamp type amps that are "channel switching" and get most of their distortion from the preamp do the best job of sounding the same quiet as they do loud. But if you want a vintage style amp your options are more limited, obviously.

[mooreamps]

Both. Power scaling will cause output tube distortion at lower volume.

On some designs you'll be distorting the power section long before the preamp when you're scaled to low voltages. Fix that balance by scaling only the output section and using a PPIMV.

I'm pretty sure Kevin and others address this- google search it.

jamie

Agreed. I use both in my equipment, except only in rock amps... The country and jazz players only want totally clean sounds.

-g

[Chuck H]

The country and jazz players only want totally clean sounds.

[mooreamps]

What ???

[R.G.]

ROFLMAO

[big_teee]

Roger That Houston!
T

[Jazz P Bass]

ROFLMAO

roflmao song - YouTube

[Chuck H]

Would that be jazz players like Larry Carlton and Al Di Meola? And country players like Brad Paisley and Keith Urban???

I just think that blanket statement isn't at all a contemporary reality. Have you listened to any counrty stations lately. I'm pretty sure the current crop of buying demographic country and jazz players want distortion as an option on their amps.

[mooreamps]

ROFLMAO

I'm buying a new car in Jan. a 2010 CLK-350... go shovel that up your Houston..

[jmaf]

I can haz severeal difficolty undertooding this thred.

[imaradiostar]

I'm buying a new car in Jan. a 2010 CLK-350... go shovel that up your Houston..

Are you sure you wanna do that? It's a girlie little benz! Get a 3 or 5 series!

jamie