Poweramp Distortion on the VH4

[FourT6and2]

I'm having an interesting discussion with someone about multichannel amps. He claims that it is impossible to get poweramp distortion from one channel while getting a clean sound from channel 1. His claim seems ridiculous, mostly because I do this every day when I practice. I'll drive the master section hard to get a good breakup on channel 2 with the gain and channel volume cranked, while channel 1 has it's gain/volume set so it doesn't break up, while channel 3 is setup so it's getting more preamp gain and it's channel volume is low.

So, that equals:

Channel 1: clean
Channel 2: poweramp clipping
Channel 3: preamp gain

Am I crazy and imagining this or what?

 

[stefvorcide]

Sounds about right to me... if you dime the master

 

[racerevlon]

The owner's manual to the VH4 states something to the effect that once you turn the master to 1 o'clock the amp is not going to get any louder, but past 1 you're going to get more power amp distortion. I tried this on CH1 and CH2 and it sounds accurate to my ears.

Cheers,

 

[nbarts]

Am I crazy and imagining this or what?

I'm afraid so.

Once I get power amp distortion out of the VH4, I don't really have a clean channel. It's kinda like clean with some breakup, which is fine by me. If you like your cleans much quieter, than no problem. I get most of my cleans rolling down the guitar volume anyway.

 

[elfredoo]

by turning up the channel volume you don't actually crank the poweramp, do you? this is a volume cascade:
A) gain which cranks the preamp
B1) channel volume
B2) master

only if channel volume AND master are turned up you get poweramp distortion (or speaker distortion) cause they both lie before the power amp tubes. so there is no cranking the poweramp (by turning up the channel volume) without turning up the master. this can only be done at lower levels by cranking channel volume and master and an attenuator between poweramp and speaker...which diezel doesn't recommend.

so if you use "power amp crankin' " you can only get clean in channel 1 by playing softly or rolling down the guitar volume.

am i right?

 

[slyvren]

my understanding of the volume structure is that the master volume is still "before" the power amp so in essence it doesn't really matter which volumes are set where as long as the poweramp gets a strong enough signal it'll distort.

I could be totally wrong though. It's happened before you know.

 

[FourT6and2]

by turning up the channel volume you don't actually crank the poweramp, do you? this is a volume cascade:
A) gain which cranks the preamp
B1) channel volume
B2) master

only if channel volume AND master are turned up you get poweramp distortion (or speaker distortion) cause they both lie before the power amp tubes. so there is no cranking the poweramp (by turning up the channel volume) without turning up the master. this can only be done at lower levels by cranking channel volume and master and an attenuator between poweramp and speaker...which diezel doesn't recommend.

so if you use "power amp crankin' " you can only get clean in channel 1 by playing softly or rolling down the guitar volume.

am i right?

Please read my post more clearly. Master is cranked. Channel 1 volume and/or gain set so it's still clean. Channel 2 set normally to get breakup.

 

[Anonymous]

The VH4 GLOBAL volume is to overall volume control for that amp and that is the volume that will delivwer the power tube saturation being discussed.
The individual ch volumes and ch gains will only deliver preamp tube saturation.

I love the ability to be able to combine power tube and preamp tube saturation.

The Schmidt also does this, but not as drastically as the VH4 can do it.

I'm using 6V6 power tubes in the Schmidt to get the power tube saturation a bit more quickly from the amp then the EL-34 will do it, and at a slightly reduced volume.

Amps with cascading channels cannot do this as it is the easy way out for obtaining distortion from the amp. However, usually with a cascading channel amp, when you make a change of a dial on one channel, it affects the tones and saturation of the other channel.

This is part of why Diezel amps offer so much more flexibility...independent channels which do not affect other channels on the amp.

 

[ericsabbath]

The VH4 GLOBAL volume is to overall volume control for that amp and that is the volume that will delivwer the power tube saturation being discussed.
The individual ch volumes and ch gains will only deliver preamp tube saturation.

that's not quite accurate
in my understanding, the power amp is always "cranked"
the master is actually what limits the output of the preamp section
channel volume is just another dedicated master before the global master
power tubes will only clip if you let enough signal come from the preamp
if you have a cranked global master, but the channel volumes set low, you won't get power amp distortion
definitely a different tone than doing the opposite, but not due to power tube breakup
an overdrive channel with a higher gain setting, more gain stages (more signal amplification) and higher channel volume setting will definitely push the power tubes (and speakers) harder than a clean channel with the gain set low, low volume setting and less (or weaker) gain stages, despite of the fact that most of its saturation is coming from the preamp

 

[RaulTx]

I agree with C-4.

What I usually on my do on my VH4 is not crank too much the channel volumes (despite the clean one) because of the preamp saturation, as C-4 says. For example, for the channel 3 volume, I leave the channel volume at 10-11 not to get too much saturation, so the distorsion is more open and clear for me (poweramp distortion). It's true that I play almost all the time at room levels, but for me, the more saturation I get from the preamp section, the dirtier it sounds (of course, it's a matter of taste).

It's an interesting post. More or less how do you combine your volume and master levels? (I'm talking about settings).

 

[dass101]

The VH4 GLOBAL volume is to overall volume control for that amp and that is the volume that will delivwer the power tube saturation being discussed.
The individual ch volumes and ch gains will only deliver preamp tube saturation.

that's not quite accurate
in my understanding, the power amp is always "cranked"
the master is actually what limits the output of the preamp section
channel volume is just another dedicated master before the global master
power tubes will only clip if you let enough signal come from the preamp
if you have a cranked global master, but the channel volumes set low, you won't get power amp distortion
definitely a different tone than doing the opposite, but not due to power tube breakup
an overdrive channel with a higher gain setting, more gain stages (more signal amplification) and higher channel volume setting will definitely push the power tubes (and speakers) harder than a clean channel with the gain set low, low volume setting and less (or weaker) gain stages, despite of the fact that most of its saturation is coming from the preamp

The above post is correct.
In all high gain amps the volume is placed after all the preamp stages, therefore it has nothing to do with preamp saturation. It just regulates how much signal is passed to the power section.
OTOH, in clean amps the volume is placed after the first preamp stage, acting more or less as a "gain", but because there are not enough stages to reach distortion, even if you crank it you only get a crunch sound, which is a combination of preamp saturation (the signal drives the following stage hard, so it clips, if it is designed that way) and power tube saturation.

In Diezel amps (and others who share the same design) the master volume is just a convenience, so you can adjust the volume for all channels at a time. The signal from all channels is summed after their individual volumes and passed through the master volume and then to the power section.

 

[FourT6and2]

The VH4 GLOBAL volume is to overall volume control for that amp and that is the volume that will delivwer the power tube saturation being discussed.
The individual ch volumes and ch gains will only deliver preamp tube saturation.

that's not quite accurate
in my understanding, the power amp is always "cranked"
the master is actually what limits the output of the preamp section
channel volume is just another dedicated master before the global master
power tubes will only clip if you let enough signal come from the preamp
if you have a cranked global master, but the channel volumes set low, you won't get power amp distortion
definitely a different tone than doing the opposite, but not due to power tube breakup
an overdrive channel with a higher gain setting, more gain stages (more signal amplification) and higher channel volume setting will definitely push the power tubes (and speakers) harder than a clean channel with the gain set low, low volume setting and less (or weaker) gain stages, despite of the fact that most of its saturation is coming from the preamp

The above post is correct.
In all high gain amps the volume is placed after all the preamp stages, therefore it has nothing to do with preamp saturation. It just regulates how much signal is passed to the power section.
OTOH, in clean amps the volume is placed after the first preamp stage, acting more or less as a "gain", but because there are not enough stages to reach distortion, even if you crank it you only get a crunch sound, which is a combination of preamp saturation (the signal drives the following stage hard, so it clips, if it is designed that way) and power tube saturation.

In Diezel amps (and others who share the same design) the master volume is just a convenience, so you can adjust the volume for all channels at a time. The signal from all channels is summed after their individual volumes and passed through the master volume and then to the power section.

Having trouble following you. What does all this mean in the end as far as getting poweramp distortion from one channel while keeping the clean channel clean?

 

[Ventura]

Am I crazy and imagining this or what?

I'm afraid so.

Once I get power amp distortion out of the VH4, I don't really have a clean channel. It's kinda like clean with some breakup, which is fine by me. If you like your cleans much quieter, than no problem. I get most of my cleans rolling down the guitar volume anyway.

+1

Once the tubes (power valves) start to saturate and give their own version of "gain", the front panel gain adjustments become redundant, to an extent. They'll fatten and compress the tone, but the signal is breaking up at the power valve section which is entirely independent of the EQ.

V.

 

[FourT6and2]

Am I crazy and imagining this or what?

I'm afraid so.

Once I get power amp distortion out of the VH4, I don't really have a clean channel. It's kinda like clean with some breakup, which is fine by me. If you like your cleans much quieter, than no problem. I get most of my cleans rolling down the guitar volume anyway.

+1

Once the tubes (power valves) start to saturate and give their own version of "gain", the front panel gain adjustments become redundant, to an extent. They'll fatten and compress the tone, but the signal is breaking up at the power valve section which is entirely independent of the EQ.

V.

So, you're saying if I'm getting poweramp distortion on channel 2, I can't get a clean sound out of channel 1? Even with channel 1's volume/gain turned down? Isn't that the same thing as using your guitar's volume control to clean up a gain channel? The poweramp won't clip if it's getting a low-level signal...

 

[phil b]

Curious to hear what Peter has to say, since he did design it.!!

 

[dass101]

The VH4 GLOBAL volume is to overall volume control for that amp and that is the volume that will delivwer the power tube saturation being discussed.
The individual ch volumes and ch gains will only deliver preamp tube saturation.

that's not quite accurate
in my understanding, the power amp is always "cranked"
the master is actually what limits the output of the preamp section
channel volume is just another dedicated master before the global master
power tubes will only clip if you let enough signal come from the preamp
if you have a cranked global master, but the channel volumes set low, you won't get power amp distortion
definitely a different tone than doing the opposite, but not due to power tube breakup
an overdrive channel with a higher gain setting, more gain stages (more signal amplification) and higher channel volume setting will definitely push the power tubes (and speakers) harder than a clean channel with the gain set low, low volume setting and less (or weaker) gain stages, despite of the fact that most of its saturation is coming from the preamp

The above post is correct.
In all high gain amps the volume is placed after all the preamp stages, therefore it has nothing to do with preamp saturation. It just regulates how much signal is passed to the power section.
OTOH, in clean amps the volume is placed after the first preamp stage, acting more or less as a "gain", but because there are not enough stages to reach distortion, even if you crank it you only get a crunch sound, which is a combination of preamp saturation (the signal drives the following stage hard, so it clips, if it is designed that way) and power tube saturation.

In Diezel amps (and others who share the same design) the master volume is just a convenience, so you can adjust the volume for all channels at a time. The signal from all channels is summed after their individual volumes and passed through the master volume and then to the power section.

Having trouble following you. What does all this mean in the end as far as getting poweramp distortion from one channel while keeping the clean channel clean?

Sorry, I wasn't adressing your question, just trying to clarify some misconceptions mentioned above.
In respect to your original question, yes, it is theoreticaly possible to drive only one channel into power amp distortion, because power amp distortion occurs only when the SIGNAL is high enough, it has nothing to do with the actual knob position or anything else. Keep the signal low on ch 1, you won't get power amp distortion, it's that easy.
However, in real life things can be different, it's very possible that in order to have you channels balanced you won't be able to crank one and keep the other low, so you will have to drive Ch1 a bit into distortion also.

 

[JasonEldon]

The owner's manual to the VH4 states something to the effect that once you turn the master to 1 o'clock the amp is not going to get any louder, but past 1 you're going to get more power amp distortion. I tried this on CH1 and CH2 and it sounds accurate to my ears.

Cheers,

man you got some great amps! how does the hughes and kettner stack up to the diezel VH4?

 

[stephen sawall]

The VH4 GLOBAL volume is to overall volume control for that amp and that is the volume that will delivwer the power tube saturation being discussed.
The individual ch volumes and ch gains will only deliver preamp tube saturation.

that's not quite accurate
in my understanding, the power amp is always "cranked"
the master is actually what limits the output of the preamp section
channel volume is just another dedicated master before the global master
power tubes will only clip if you let enough signal come from the preamp
if you have a cranked global master, but the channel volumes set low, you won't get power amp distortion
definitely a different tone than doing the opposite, but not due to power tube breakup
an overdrive channel with a higher gain setting, more gain stages (more signal amplification) and higher channel volume setting will definitely push the power tubes (and speakers) harder than a clean channel with the gain set low, low volume setting and less (or weaker) gain stages, despite of the fact that most of its saturation is coming from the preamp

The above post is correct.
In all high gain amps the volume is placed after all the preamp stages, therefore it has nothing to do with preamp saturation. It just regulates how much signal is passed to the power section.
OTOH, in clean amps the volume is placed after the first preamp stage, acting more or less as a "gain", but because there are not enough stages to reach distortion, even if you crank it you only get a crunch sound, which is a combination of preamp saturation (the signal drives the following stage hard, so it clips, if it is designed that way) and power tube saturation.

In Diezel amps (and others who share the same design) the master volume is just a convenience, so you can adjust the volume for all channels at a time. The signal from all channels is summed after their individual volumes and passed through the master volume and then to the power section.

Having trouble following you. What does all this mean in the end as far as getting poweramp distortion from one channel while keeping the clean channel clean?

Sorry, I wasn't adressing your question, just trying to clarify some misconceptions mentioned above.
In respect to your original question, yes, it is theoreticaly possible to drive only one channel into power amp distortion, because power amp distortion occurs only when the SIGNAL is high enough, it has nothing to do with the actual knob position or anything else. Keep the signal low on ch 1, you won't get power amp distortion, it's that easy.
However, in real life things can be different, it's very possible that in order to have you channels balanced you won't be able to crank one and keep the other low, so you will have to drive Ch1 a bit into distortion also.

I believe this true of all tube amps .... the power section is always cranked .... it is only a matter of getting enough signal into it to overdrive. If the signal is clean or not it does not matter ... it is the level into it that well get poweramp distortion.